Specific Infections
Question.1. Describe clinical features and treatment of gas gangrene.
Answer. It is highly fatal spreading infection caused by Clostridium organism, which result in “myonecrosis”.
- It is also known as clostridial myositis, clostridial myonecrosis, and infective gangrene of muscles.
- The most common causing agent is Clostridium welchii.
Clinical Features
- Presence of features of toxemia, fever, tachycardia and pallor.
- Wound is under tension with foul smelling discharge.
- Color of skin is khaki brown due to hemolysis.
- Crepitus can be felt.
- Jaundice can be present and oligouria signifies renal failure.
- Most commonly the site affcted are adductor region of lower limb and buttcks and subscapular region in upper limb.
Read And Learn More: General Surgery Question And Answers
Treatment
- Injection benzyl penicillin 20 lacs 4 hourly + lnjection metronidazole 500 mg 8 hourly + lnjection aminoglycosides or third generation cephalosporins or metronidazole.
- Fresh blood transfusion.
- Polyvalent antiserum 25,000 units given intravenously after a test dose and repeated after 6 hours.
- Hyperbaric oxygen is very useful.
- Liberal incisions are given. All dead tissues are excised and debridement is done until healthy tissue bleeds.
- Rehydration and maintaining optimum urine output.
- Electrolyte management is done.
- In severe cases, amputation has to be done as a life-saving procedure-stump should never be closed (Guillotine amputation).
- Often ventilator support is required.
- Once a ward or peration theater is used for a patient with gas gangrene, it should be fumigated for 24–48 hours properly to prevent the risk of spread of infection to other patients especially with open wounds.
- Hypotension in gas gangrene is treated with whole blood transfusion.
Question.2. Describe briefl gas gangrene.
Or
Write short note on gas gangrene.
Or
Write in short about gas gangrene.
Or
Describe gas gangrene, etiology and management
Answer.
Defiition: This is a spreading infective gangrene of the muscles characterized by collection of gas in the muscles and subcutaneous tissue.
As this condition is caused by Clostridium infection, it is also called ‘Clostridium myonecrosis’.
Etiology
Gas gangrene is caused by Clostridium perfringens which is the most common microorganism.
Various other organisms causing gas gangrene are Clostridium septicum, Clostridium redemptions, Clostridium histolyticum.
Predisposing Factors
- Contaminated, manured or cultivated soil, intestines are the sources.
- Fecal flra commonly contains clostridial organisms enters the wound; in presence of calcium from blood clot or silica (silicic acid) of soil, it causes infection.
- It is common in crush wounds, following road traff accidents, after amputations, ischemic limb, gunshot wounds, war wounds.
- Injury or ischemia or necrosis of the muscle due to trauma predisposes infection.
- Anaerobic environments in the wound-initial infection with aerobic organism utilizes existing oxygen in tissues creating anaerobic environment to cause clostridial sepsis.
Types
- Subcutaneous type: This is a crepitant infection involving necrotic tissue, but healthy muscles are not involved.
- Cellulitis is characterized by foul smelling, seropurulent infection of a wound.
- Single muscles type: The infection is limited to one muscle.
- Group type: The gas gangrene is limited to one group of muscles.
- Massive type: The gas gangrene involved almost the whole muscle mass of one limb.
- Fulminating type: In this condition, the gas gangrene spreads very rapidly even beyond the limb and is often associated with intense toxemia with high fatal rate.
Clinical Features
- Presence of features of toxaemia, fever, tachycardia and pallor.
- Wound is under tension with foul-smelling discharge.
- Color of skin is khaki brown due to hemolysis.
- Crepitus can be felt.
- Jaundice can be present and oligouria signifies renal failure.
- Most commonly the site affcted are adductor region of lower limb and buttcks and subscapular region in upper limb.
Investigations
- X-ray shows gas in muscle plane or under the skin.
- Liver function tests, blood urea, serum creatinine, total count, PO2, PCO2
- CT scan of the part may be useful, especially in chest or abdominal wounds.
- Gram stain shows gram-positive bacilli.
- Robertson’s cooked meat media is used which causes meat to turn pink with sour smell and acid reaction.
- Clostridium welchii is grown in culture media containing 20% human serum in a plate.
- Antitoxin is placed in onehalf of the bacteria grown plate sparing the other half.
- Zone of opacity will be seen in that halfofthe plate where there is no antitoxin. In the other half part of the plate where there is antitoxin there is no opacity-Nagler reaction.
Complications
- Septicemia, toxemia
- Renal failure, liver failure
- Circulatory failure, Disseminated intravascular coagulation, secondary infection.
- Death occurs in critically ill patients.
Treatment
- Injection benzyl penicillin 20 lacs 4 hourly + lnjection metronidazole 500 mg 8 hourly + lnjection aminoglycosides or third generation cephalosporins or metronidazole.
- Fresh blood transfusion.
- Polyvalent antiserum 25,000 units given intravenously after a test dose and repeated after 6 hours.
- Hyperbaric oxygen is very useful.
- Liberal incisions are given. All dead tissues are excised and debridement is done until healthy tissue bleeds.
- Rehydration and maintaining optimum urine output.
- Electrolyte management is done.
- In severe cases, amputation has to be done as a life-saving procedure-stump should never be closed (Guillotine amputation).
- Often ventilator support is required.
- Once a ward or Operation theatre is used for a patient with gas gangrene, it should be fumigated for 24 – 48 hours properly to prevent the risk of spread of infection to other patients especially with open wounds.
- Hypotension in gas gangrene is treated with whole blood transfusion.
Question.3. Write short note on cancrum oris.
Answer. It is also called as NOMA or gangrenous stomatitis.
- It is a rapidly spreading gangrene of oral and facial tissues occurring in deliberated or nutritionally defiient person.
- The disease is caused by Borrelia vincentii and fusiformis bacteria.
Predisposing Factors
- Low socioeconomic status: It occurs in people of low socio economic status or in poverty.
- Diseases: In debilitated diseases such as diphtheria,measles, pneumonia, scarlet fever, etc.
- Injury: In cases with mechanical injury.
- Immunodefiiency state: In AIDS
- Poor Oral hygiene: This leads to growth of bacteria causing increase chances of infection.
Clinical Features
- It is seen chiefly in children mainly in malnourished children.
- The common sites are areas of stagnation around fied bridge or crown.
- The commencement of gangrene is denoted by blenching of skin.
- Small ulcers of gingival mucosa spread rapidly and involve surrounding tissue of jaws, lips and cheeks by gangrenous necrosis.
- Odor is foul. Patient has high temperature during course of disease, suffrs secondary infection and may die from toxemia.
- Overlying skin is inflmed, edematous and fially necrotic which results in formation of line of demarcation between healthy and dead tissue.
- In advanced stage, there is blue black discoloration of skin.
- As gangrenous process advances, slough appears and soon separated, leaving perforating wound in involved area.
- The large masses maybe sloughed outleavingjaws exposed.
Treatment
- Systemic antibiotics should be given, i.e. high dose penicillin and metronidazole.
- Thorough nasogatric tube, high protein and vitamin rich diet should be given.
- Blood transfusion is given.
- Parenteral flid is given.
- Wound irrigationand liberal excision of dead tissue is done.
- Later on patient require flp to cover the defect.
Question.4. Describe various syphilitic lesion of lip and oral cavity.
Or
Write short note on syphilis
Answer.
Diagnosis
- By blood tests using treponemal or non treponemal tests.
- Non-treponemal tests are used initially and are VDRL and rapid plasma regain tests.
- Positive confimation is required by treponemal test such as Treponema pallidum particle agglutination or florescent
treponemal antibody absorption test.
Treatment
- Primary and secondary syphilis are treated by injection procaine penicill in 10 lakh units IM for 14 days.
- In late syphilis, the above-mentioned treatment should be continued for 21 days.
Question.5. Write short note on actinomycosis.
Or
Write short note on actinomycosis of jaw.
Or
Write brief answer on actinomycosis.
Answer.
It is a chronic granulomatous suppurative disease which is caused by anaerobic or microaerophilic Gram-positive non-acid-fast branched fiamentous bacteria.
The most common organism is Actinomyces israelii, A.naeslundii, A. viscosus, A. odontolyticus and A. propionica.
Clinical types of actinomycosis
- Faciocervical: It is the most common type. Infection spreads either from tonsil or from adjacent infected tooth.
- Initially,an induration develops. Nodules form with involvement of skin of face and neck. It softens and bursts through the skin as sinuses which discharge pus- which contains sulphur granules (60%).
- Thorax: Lungs and pleura get infected by direct spread from pharynx or by aspiration. Empyema develops.
- Later chest wall nodules appear leading to sinuses with discharge (20%).
- In right iliac fossa: It presents as a mass abdomen with discharging sinus.
- Liver is infected through portal vein (Honeycomb liver).
- Pelvic: Pelvic actinomycosis can occur due to intra—uterine devices.
Pathogenesis
Organism enters through deeper plane of the tissue,causes subacute inflammation with induration and nodule formation.
Eventually discharging sinus forms at the surface.
Pus collected in a swab or sterile tube will show sulphur granules.
Predisposing Factors
- Trauma
- Presence of carious tooth
- Secondary bacterial invasion
- Hypersensitivity reaction.
Clinical Features
Cervicofacial actinomycosis/ actinomycosis of Jaw/Faciomaxillary
- Its occurrence is more common in males.
- Disease may remain localized to soft tissues or spread to involve salivary glands, bone (maxilla or mandible), skin of face and neck.
Most commonly involve area is submandibular region. - Presence of trismus is there before formation of pus.
- The disease is characterized by presence of palpable mass which is indurated and is painless. Skin surrounding the lesion has wooden indurated area of firosis.
- Multiple subcutaneous nodules over bluish-colored skin of jaw.
- Nodules rupture resulting in multiple discharging sinuses.
Abdominal Actinomycosis
- It is more severe form of disease.
- Patient complains of fever with chills and vomiting.
- There is involvement of liver and spleen.
- On palpation, abdominal mass is felt which is the sign in diagnosis of disease.
Thoracic Actinomycosis
- Patient gives history of aspiration.
- Dry or productive cough, occasionally blood streaked sputum, shortness of breadth and chest pain.
- Sinus tracts are present with drainage from chest wall.
Pelvic Actinomycosis
- History of IUCD is present.
- Presence of lower abdominal discomfort, abnormal vaginal bleeding or discharge.
Investigations
- Pus under microscopy shows branching fiaments.
- Gram ’s staining shows Gram-positive mycelia in centre with Gram-negative radiating peripheral fiaments.
These clubs are due to host reaction which are lipoid material (antigen-antibody complex). - Cultured in brain heart infusion agar and thioglycolate media.
Differential Diagnosis
- Chronic pyogenic osteomyelitis.
- Carcinomas at the site
- Tuberculous disease
Management
- Penicillins are the drug of choice and should be given for longer period (6 to l2 weeks). If patient is allergic to penicillin doxycycline can be given.
- Antifungals are often given because it is fungal-like bacterium.
- Surgical debridement is occasionally required. Surgical therapy include incision and drainage of abscess, excision of sinus tracts and recalcitrant firotic lesions, decompression of closed space infections and the interventions which are aimed for relieving the obstruction.
- Welsh regimen: Injection amikacin l5 mg/kg IV daily for 2l days; such cycle is repeated 3 times at a gap of l5 days along with tablet trimethoprim (7 mg/kg)—sulfamethoxazole (35 mg/kg) daily for 6 months.
Question.6. Write the clinical features of faciomaxillary Actinomycosis.
Answer. It is caused by the Actinomycosis israelii.
Clinical Features
- Age: Commonly seen in adult male.
- Cause: Dental plaque, calculus, gingival debris, bad carious tooth.
- Location: Submandibular region is the most frequent site of infection. Cheek, masseter region and parotid gland may also involve.
- Symptoms: Trismus is a common feature, before pus formation.
Signs
- The fist sign of infection is the presence of palpable mass.
- Mass is painful and indurated.
- Multiple subcutaneous nodules over bluish-colored skin of jaw.
- The nodules rupture resulting in multiple discharging sinuses.
- The discharge contains sulphur granules.
- Lymph nodes are not involved.
Question.7. Write short note on candidal infection of oral cavity.
Answer. Oral Candidiasis is most commonly associated with
Candida albicans.
Oral Candidal Infection
Thrush (Pseudomembranous candidiasis):
- It is superfiial infection of upper layer of mucous membrane.
- Characterized as creamy white removable plaque on the oral mucosa and caused by overgrowth of fungal hyphae mixed with desquamated epithelium and inflmmatory cells.
- This type of candidiasis may involve any part of the mouth or pharynx.
Acute atrophic candidiasis:
- It is also called as “Antibiotics sore mouth”.
- It appears as flt, red patches of varying size.
- It commonly occurs on the palate and the dorsal surface of the tongue.
Chronic hyperplastic candidiasis:
- It is called as “candidal leukoplakia”.
- It present as fim and adherent white patches in the oral mucosa.
- It occurs on cheek, lip and tongue.
- Symptoms of oral candidal infection: Including burning mouth, problemineatingspicyfood and change intaste.
Treatment
- Removal of the cause.
- Topical treatment: Clotrimazole, nystatin, ketoconazole or amphotericin in ointment or cream base, suspension.
- Systemic treatment:
- Nystatin 250 mg TDS for 3 weeks.
- Ketoconazole 200 mg once daily.
- Fluconazole 100 mg once daily.
- Itraconazole 100 mg may be used.
Question.8. Discuss etiology, clinical features. Differential diagnosis and treatment of tetanus.
Or
Discuss the clinical features and management of tetanus
Or
Discuss etiology, clinical features and management of tetanus.
Answer. Tetanus is also called as lockjaw.
It is a disease of nervous system characterized by intensive activity ofmotor neuron and resulting in severe muscle spasm.
Etiology
It is caused by anaerobic, gram-positive Bacillus Clostridium tetani.
Clinical Features
Symptoms
- Trismus is common.
- Presence of jaw stiffess and pain.
- Sweating is present and patient is anxious.
- Presence of headache, delirium and sleeplessness.
- Presence of dysphagia and dyspnea.
Signs
- Spasm and rigidity of all muscles.
- Hyper-reflxia
- Respiratory changes due to laryngeal muscle spasm,infection, aspiration.
- Tonic-clonic convulsions.
- Abdominal wall rigidity often with hematoma formation.
- Severe convulsion may often lead to fractures, joint dislocations and tendon ruptures.
- Fever and tachycardia.
- Retention of urine (due to spasm of urinary sphincter),constipation (due to rectal spasm).
- Rarely features of carditis are seen due to involvement of the cardiac muscle, which is dangerous, as it often leads to cardiac arrest and death.
- Symptoms will be aggravated by stimuli-like light and noise.
Differential Diagnosis
- Strychnine poisoning
- Trismus due to various causes such as dental, oral, tonsillar sepsis, oral malignancy.
- Meningitis
- Hydrophobia
- Convulsive disorders
- Epilepsy
- Symptomatic hyperactivity.
Treatment/Management
- Patient is admittd and isolated in a dark, quiet room.
- Antitetanus globulin (ATG), 3,000 units IM single dose is given.
- Anti-tetanus serum (ATS): When ATG is not available or when patient cannot affrd, after IV test dose (l ,000 units
of ATS), full dose is given, i.e. l,00,000 units, half of it is given IM and half of it is given IV. - Wound debridement, drainage of pus, injection of ATG 250-500 units locally to reduce the toxin effct.
- Ryle’s tube has to be passed, initially to decompress, so as to prevent aspiration, but later for feeding purpose.
- Catheterization should be done.
- IV flids and electrolyte balance has to be maintained.
- Tetanus toxoid should be given as disease will not give immunity against further infections.
- To start fist dose, second dose after one month, third dose after six months.
- Aluminum phosphate absorbed tetanus toxoid 0.5 mL is injected into deltoid muscle.
- Booster dose should be given every 4 years or after any signifiant trauma.
- In patients who have not been immunized earlier it needs 30 days to to develop antibody after tetanus toxoid injection.
- IV diazepam 20 mg 4th or 6th hourly. Dose is adjusted depending on severity and convulsions.
- IV phenobarbitone 30 mg 6th hourly.
- IV chlorpromazine 25 mg 6th hourly.
- Injection crystalline penicillin 20 lacs 6th hourly and injection gentamicin and metronidazole to prevent secondary infection.
- Regular suction and clearance of respiratory tract.
- Nasal oxygen is given.
- In severe cases, patient is curarised and placed in ventilator.
- Endotracheal intubation or tracheostomy are often lifesaving procedures.
- Good nursing care: Change of position, prevention of bedsores, prevention of DPT.
- Chest (respiratory) physiotherapy during recovery period.
- Steroids are given when carditis is suspected.
- Cardiac pacemaker may be useful in refractory bradycardia and arrhythmias.
- Following treatment patient often gets spasm of diffrent muscles (tics) for a long period which can be prevented by giving methocarbamol for 6 months to one year.
Question.9. Write short note on tetanus prophylaxis.
Or
Discuss about prophylaxis of tetanus.
Or
Write short note on prophylaxis against tetanus.
Answer.
Tetanus Prophylaxis
- In adults in which fresh immunization to start second in one month, next in 6 month period. Tetanus toxoid 0.5 mL IM Booster dose should be given once in every 4 years or after any signifiant trauma.
- Tetanus neonatorum can be prevented by immunization of the mother with two tetanus toxoid injection, ½ mL IM in third trimester of pregnancy.
- Infants and children are immunized with tetanus toxoid,Diphtheria and Pertussis vaccine (DPT) three dose at 6, 10,14 weeks of age.
- This is called “Triple antigen”.
- A booster dose is given at 18 months and once in fie years, 1 mL of tetanus toxoid is given to achieve active immunity.
- ATG- 500-1000 units IM given as prophylaxis in road accident, severe burns, crush injuries, war wounds, penetrating wounds and wounds of head and face.
Question.10. Write short note on AIDS.
Answer. AIDS—Acquired immunodefiiency syndrome.
AIDS is the end stage ofa progressive state ofimmunodefiiency.
Causative organism: Human immunodefiiency virus (HIV).
Mode of transmission
- Sexual intercourse
- Mother to fetus
- Through contaminated needles
- Through contaminated blood transfusion.
General Features
- Weight loss more than l0%.
- Fever more than l month.
- Diarrhea more than l month.
- Neuralgia, arthralgia, headache.
- Generalized lymphadenopathy.
- Cutaneous rashes, dermatitis, fungal, bacterial, viral (herpes simplex l and 2) infection.
- Dental infection, gingivitis, candidiasis of oral cavity and esophagus.
- Varicella zoster infection.
- Opportunistic infections
- Poor healing after surgery, trauma, infection with more complications.
Investigations
- ELISA test is the screening test
- Western blot is the confimatory test
- Polymerase chain reaction
- Anti-HIV detection
- CD4+ count
- Normal value is >500/mm3
- Values between 200 to 500/mm3 is seen in Kaposi’s sarcoma and candidiasis
- Values between 50 to 200/mm3 is seen in Pneumocystis carinii and
- Toxoplasma infection.
- Values <50/mm3 is seen in atypical mycobacteria,cytomegalovirus, lymphomas.
As patient is HIV infected, a time gap occurs for these tests to become reactive. This time gap is known as window period.
During this period, person in infected.
Treatment
- Antiviral therapy or HAART therapy
- Nucleoside reverse transcriptase inhibitor (NRTI):
- Zidovudine, didanosine, abacavir, lamivudine,stavudine.
- Non-nucleoside reverse transcriptase inhibitor (NNRTI):
- Nevirapine, delavirdine.
- Protease inhibitors: Ritonavir, indinavir, amprenavir.
- Treatment of opportunistic infections.
- Treatment of tumors.
- Immunotherapy:
- Alpha and gamma interferons.
- Interleukins.
- Bone marrow transplantation.
- Anti-CD3 or IL-2 after HAART (Highly Active AntiRetroviral Therapy).
- Psychotherapy
- Counseling of HIV patients and their families.
- Life-expectancy after initial HIV infection is 8–l0 years.
Prevention and Control
- Safe sexual contact (use of condom)
- Prevent sharing of needles among drug abusers.
- Separate and sterilized needle should be used for each patient.
- Blood transfusion should be done after HIV testing.
- Health education.
Questioni.11. Describe etiology, epidemiology, pathology and prevention of AIDS in dental practice.
Answer. Etiology (in dental clinic)
- Due to infected instruments.
- Uses of infected needles.
- Infected blood transfusionduring dental procedures.
- Contaminated gloves and dressing materials.
Epidemiology
- AIDS was fist describe in US the disease has now attined high proportions involving all continents.
- Africa constitutes 50% of all positive cases globally
- 1 in every 100 sexually active adult worldwide is infected with HIV.
- In India epicenter of epidemic lies in states of Maharashtra or Tamil Nadu which together compromise about 50% HIV
Pathology
It is largely related to depletion of CD4 + T-cells resulting in:
Prevention in dental Clinic
- Needle sharing among patients is avoided.
- Instruments are properly sterilized by autoclave or proper use of chemical sterilization.
- Before commencement of surgery dentist should use proper asepsis measures.
- Patient should be educated about AIDS.
Question.12. Write in brief about the HIV and dental surgeon.
Answer. HIV is the virus which results in the causation of the AIDS.
Prophylactic measures to be adopted by dental surgeon while treating AIDS patient.
In OPD
- Any patient with open wound, gloves are worn when examining a patient.
- During dental diagnostic procedure gloves should be worn.
- Use disposable instruments.
- Reusable instruments are cleaned in soap and water and emerged in glutaraldehyde.
- No surgical procedure involving sharp instrument should be performed in OPD.
In Operating Room
- Dental chair is covered with a single sheet of polythene.
- The number of personnel in dental operating room should be reduced to minimum.
- The staf with abrasion or lacerations on their hands is not allowed inside the operating room.
- Staff who enter the theater wear overshoes, gloves and disposable water-resistant gowns, and eye protectors.
Surgical technique
- Avoid sharp injury.
- Avoid “needlestick” injuries
- Proper autoclaving at the end of surgery.
AZT—Zidovudine, lamivudine and indinavir should be given for the health workers following exposure of susceptible area to infected material from AIDS patient.
Question.13. Write short note on prevention and precautions to be taken on treating a HIV-positive patient.
Or
Write short note on precautions to be taken while treating surgical patient with HIV
Or
Write in brief on universal precaution for AIDS.
Or
Write briefl on universal precautions in HIV and hepatitis.
Answer.
Preventions and Precautions to be taken While treating a HIV Positive or Hepatitis B Patient
- Care in handling sharp objects such as needles, and blades.
- All cuts and abrasions in an HIV or hepatitis B patient should be covered with a waterproof dressing
- Minimal parenteral injections
- Equipment and areas which are contaminated with secretions should be wiped with sodium hypochlorite solution or 2% glutaraldehyde.
- Contaminated gloves, cottns should be incinerated.
- Equipments should be disinfected with glutaraldehyde.
- Disposable equipment (drapes, scalpels, etc.) should be used, whenever possible.
- Walls and flor should be cleaned properly withsoap water.
- Separate operation theatre and staf to do surgeries to HIV or hepatitis B patients is justifible
- Avoid shaving whenever possible before surgery in HIV or hepatitis B patients.
- All people inside the theater should wear disposable gowns, plastic aprons, goggles, overshoes and gloves.
- Surgeons, assistants and scrub nurse should wear in addition double gloves.
- Suction bottle should be half-filed with freshly prepared glutaraldehyde solution.
- Soiled body flids should be diluted with glutaraldehyde.
- Accidental puncture area in surgeon or scrub nurse should immediately washed with soap and water thoroughly
- Theater should be fumigated after surgery to HIV or hepatitis B patient.
Question.14. Write briefly on necrotizing fasciitis or subdermal gangrene.
Answer. It is defined as rapidly progressing necrosis of subcutaneous tissue and fascia usually sparing the muscles and accompanied by toxicity, high fever and apathy.
Etiology
Bacteria such as Streptococcus pyogenes, anaerobes, coliforms,Gram-negative organisms
Types
- Type I: Polymicrobial (80%): Mixed infection; by non—group A streptococci with anaerobes or clostridial or enterobacteriaceae (E coli, Pseudomonas).
It is common in perineum, trunk and postoperative wounds; common in diabetics and immunosuppressed people. - Type II: Monomicrobial: It is due to group A hemolytic streptococci or methicillin-resistant Staphylococcus aureus (MRSA).
It is common in young individual; common in extremities without any comorbid status. - Type III: It is Gram-negative rod (Vibrio vulficus) after a minor trauma; associated with chronic liver disease,diabetes, steroid therapy, chronic kidney disease. It is rare.
- Type IV: It is due to fungal infection commonly, Aspergillus zygomycetes. it is also rare.
Predisposing Factors
- In old age
- In smokers
- Diabetics
- Immunosuppressed individuals
- Malnourished
- Obesity
- Patients on steroid therapy
- HIV patients.
Clinical Features
- Lesion occurs in limbs, lower abdomen, groin and perineum.
- Presence of sudden swelling and pain in part with edema,discoloration, necrotic areas and ulceration.
- Presence of foul-smell discharge
- Presence of high-grade fever with chills and hypotension
- Oliguria with acute renal failure due to tubular necrosis.
- Jaundice.
- Rapid spread in short period (in few hours).
- Features of multiple organ dysfunction syndrome with drowsy, ill-patient.
- Condition, if not treated properly may be life-threatening.
- The subdermal spread of gangrene is always much more extensive than appears from initial examination.
Management
- IV flids, fresh blood transfusion.
- Antibiotics depend on culture and sensitivity or broadspectrum antibiotics. High-dose penicillins are very effctive.
Clindamycin, third-generation cephalosporins, aminoglycosides are also often needed. - Catheterization and monitoring of hourly urine output.
- Electrolyte management and monitoring.
- Control of diabetes, if patient is diabetic.
- Oxygen, ventilator support, dopamine, dobutamine supplements, whenever required.
- Radical wound excision of gangrenous skin and necrosed tissues at repeated intervals.
- The vacuum-assisted dressing is given.
- Once patient recovers and healthy granulation tissue appears split skin grafting is done. Mesh graft is needed.
Question.15. Define and describe differentiating features of tetanus and gas gangrene.
Answer.
Question.16. Enumerate diffrences between virus of Hepatitis B and HIV.
Answer.
Question.17. Enumerate differences between tetanus and strychnine poisoning.
Answer.
Question.18. Write short note on candidiasis.
Answer. Candidiasis is the fungal infection caused by yeast-like
fungus, i.e. Candida albicans.
Types of Candidiasis
Primary candidiasis:
Acute form:
- Pseudomembranous
- Erythematous
Chronic form:
- Hyperplastic
- Erythematous
- Pseudomembranous
Candida-associated lesion:
- Denture stomatitis
- Angular stomatitis
- Median rhomboid glossitis
Keratinized primary lesion super-infected with Candida:
- Leukoplakia
- Lichen planus
- Lupus erythematosus
Secondary candidiasis
Predisposing Factors
- Changes in oral microbial flora: Marked changes in oral microbial flora can be seen during administration of systemic antibiotics, due to chronic use of mouth rinses, and xerostomia due to anticholinergic agent. These all lead to candidiasis.
- Local irritant: Local irritants such as denture, due to heavy smoking, orthodontic appliances can lead to candidiasis.
- Drug therapy: Administration of immunosuppressive agents, corticosteroids, head and neck radiotherapy can cause candidiasis.
- Acute and chronic diseases: Various acute and chronic diseases such as leukemia, diabetes, tuberculosis can cause candidiasis.
- Malnutrition state: Low serum vitamin A, low iron level and low pyridoxine levels may lead to candidiasis.
- Endocrinopathy: Endocrinopathies such as hyperparathyroidism, hypothyroidism and Addison’s disease can cause candidiasis.
Clinical Features
- It is more common in females as compared to males.
- Commonly affected sites are the roof of mouth, retromolar area, mucobuccal fold and tongue.
- Patient complaints of bad taste and spicy food can cause discomfort.
- Pearly white or bluish white plaques are seen on mucosa.
Mucosa adjacent to these plaques appears red and moderately swollen. - White patches are easily wiped of with wet guage which leaves normal or erythematous area.
- Candida in chronic form does not rub of by lateral pressure.
- Lesions are slightly white to dense white with cracks and fisures occasionally present.
- Borders are often vague, which produces appearance of epithelial dysplasia.
Diagnosis
Clinically, the pseudomembranous lesion is scrapped of which is diagnostic of candidiasis.
Treatment
Removal of cause:
- Any of the local irritants should be removed.
- With drawal of antibiotics is done.
Topical treatment:
- Clotrimazole, one troche 10mg is dissolved in mouth for 5 times a day.
- Nystatin oral pastilles can be given, i.e. one or two pastilles fie times a day.
- Amphotericin B 5–10 mL of oral solution used as rinse and then expectorated 3 to 4 times a day.
Systemic treatment:
- Nystatin 250 mg TDS for 2 weeks followed by 1 troche per day for third week.
- Ketoconazole 200 mg tablet with food once daily.
- Fluconazole 100 mg tablet OD for 2 weeks
- Itraconazole 200 mg tablet OD for 2 weeks
Question.19. Describe etiopathogenesis, clinical features and management of tetanus.
Answer.
Etiopathogenesis
Tetanus is caused by Gram-positive, anaerobic, motile, noncapsulated, organism with peritrichous flgella with terminal spores, i.e. bacillus Clostridium tetani.
Spore is the infective agent and is found in soil, dust, manure, etc. Spore enters the wound through prick injuries which result from road traffic accidents, penetrating injuries, foreign body, etc.
Question.20. Write short note on prophylaxis of hepatitis B.
Answer. Following is the prophylaxis of hepatitis B:
- Recombinant hepatitis B vaccine having HBsAg capable of producing active immunization.
- Usually, three injections of vaccine should be given IM during current, fist and sixth months. These vaccinations provide 90% of prophylaxis from hepatitis B virus.
- If patient is immunocompromised larger doses of vaccination should be given.
- Passive immunization is provided by I.M. injection of hyperimmune serum globulins which is given within 24 hours or almost within a week of exposure to infected blood.
- Active along with passive immunization is provided to the paramedics who has undergone needle stick injury, to newborn babies of hepatitis B positive mothers and to regular sexual partner of hepatitis B positive patient.
Dosage is 500 IU for adults and 200 IU for babies.
Following precautions are to be taken for prevention from hepatitis B:
- Avoid infected blood transfusion, body organs,sperms and other tissues. Blood should be screened before transfusion.
- Strict sterilization process should be ensured in clinics.
- Presterilized needles and syringe should be used.
- Avoid injections unless they are absolutely necessary.
- Carrier should be told not to share razors or tooth brushes, use barrier methods of contraception, avoid blood donation.
Question.21. Write briefl on primary chancre.
Or
Write short note on primary chancre.
Answer.
- Primary chancre is the hallmark sign of primary syphilis caused due to Treponema pallidum.
Primary chancre is also known as Hunterian chancre or hard chancre. - Primary chancre occurs on penis of males and cervix of females. It can also be seen over extragenital sites such as figers, perianal region, nipples, lips tonsils, tongue and palate.
- Chancre is slightly raised, ulcerated, non-tender, nonbleeding and fim plaque which is round, indurated along with rolled raised edges.
- It starts as a papule, then enlarges to various centimeters and converted to ulcer.
- Intraorally chancre appears as narrow copper colored with slight raised borders and in center with reddishbrown base.
- Chancre remains painless before get infected after infected it becomes tender.
- Chancre can disappear after 10 days without any therapy.
Question.22. Define and classify surgical infection. Describe the surgical principles and treatment of infection in dental
surgery.
Answer.
Surgical infections
A disease caused by microorganisms especially those that release toxins or invade body tissue during or after surgical procedures.
Classification of Surgical Infections
According to depth ofwound infection:
- Superficial incisional surgical site infection
- Deep incisional surgical site infection
- Organ space infection.
According to etiology:
- Primary infection
- Secondary infection.
According to the time:
- Early infection
- Intermediate infection
- Late infection.
Surgical Principles in dental Surgery
- Follow the shortest and most direct route to the accumulation of exudates or pus, but always preserve integrity of anatomical structures.
- Performing incisions with esthetic criteria in areas of minimal impact as on the face.
- Place the incisions in areas of healthy mucosa or skin,avoiding areas with flctuation and atrophic alterations.
- Perform strictly cutaneous or mucosal incisions (with a No. 11 blade)
- The incision is penetrated using hemostat or sinus forceps in closed position, advanced into the pus locules, by blunt dissection in open position of the sinus forceps.
The hemostat is withdrawn in the same position in open state to avoid damage to anatomical structures such as nerves, vessels. - Choice of appropriate drainage material is according to the site of infection. Avoid using gauze as drainage material,since secretions would be retained and coagulate, thereby creating a tamponade that would cause the infection to persist.
Treatment Of Infection In Dental Surgery
Excision of sinus:
- In most of the cases, the abscess escapes the tissue spaces spontaneously, through a sinus if left without any treatment for sufficient period of time.
- Pus discharge through the skin in a location unfavorable for drainage follows and the resulting scar is always puckered, thickened, and depressed.
- Further, the sinus will become chronic unless the original source of infection is removed, and it is subjected to exacerbations and remissions with attempts at healing during the quiescent phase.
- To treat this sinus, an elliptical incision is made around its external orifie so that on closure the scar lies in Langer’s line without puckering.
- This is done with scissors, using which the sinus tract is followed to its source which is usually found on the bony surface of the jaws.
Then a deep soluble suture is inserted to eliminate the dead space and the skin wounds are closed with careful eversion of the edges.
Antibiotic therapy:
Since dental infections are caused by aerobic and anaerobic bacteria following antibiotics are given:
- Amoxycillin with clavulanic acid 2 g one hour prior to surgery followed by 2 g every 12 hours for 5 to 7 days.
- As an alternative regime clindamycin 300 mg every 6 hourly for 5–7 days can be given.
- When the patient fails to respond to empirical antibiotic therapy and after treatment of the causes within 48 hours.
- When the infection is disseminated to other fascial spaces despite initial treatment.
- In an immunosuppressed patient, or ifhe/she has prior history of bacterial endocarditis and does not respond to the initial antibiotic.
Supportive therapy:
- Apart from antibiotic therapy, patients with dental infection may require complementary measures, particularly in severe cases with considerable systemic involvement or in life-threatening situations.
- Analgesics, nonsteroidal anti-inflammatory drugs (NSAIDs) and nutritional support are mandatory.
- Patients with infection and fever present considerable loss of body fluids—250 mL for every degree (centigrade) temperature rise.
- Ambulatory patients must drink 8–10 glasses of water or any other liquid.
- Intravenous flids can be given to those patients who are hospitalized to improve hydration.
- The daily calorie requirement also increases by 13% for each degree (centigrade) above normal body temperature.
- Thermal agents should be used to aid the body defenses.
- Heat produces vasodilatation and increased circulation, more rapid removal of tissue breakdown products, and greater influx of defensive cells and antibodies.
- A crucial aspect to be considered in these patients is the potential risk onset of respiratory impairment,requiring airway monitoring, perhaps even on an emergency basis, by means of endotracheal intubation, cricothyrotomy or tracheotomy.
Question.23. Write short note on AIDS and surgeon.
Or
Write in brief about HIV and surgeons.
Answer. The HIV is the virus which results in the causation of the AIDS.
Prophylactic measures to be adopted by surgeon while treating AIDS patient.
In OPD
- Any patient with open wound, gloves are worn when examining a patient.
- During proctoscopy or sigmoidoscopy, gloves should be worn.
- Hand gloves and eye protection during flxible endoscopy.
- Use disposable instruments.
- Reusable instruments are cleaned in soap and water and emerged in glutaraldehyde.
- No surgical procedure involving sharp instruments is performed in OPD.
In Operating Room
- Operating table is covered with a single sheet of polythene.
- The number of personnel in operating room should be reduced to minimum.
- The staff with abrasion or lacerations on their hands is not allowed inside the operating room.
- Staff who enter the theater wear over-shoes, gloves and disposable water-resistant gowns and eye protectors.
Surgical technique
- Avoid sharp injury.
- Prefer scissors or diathermy to scalpel
- Use of skin clips
- Avoid “needle-stick” injuries
- Proper autoclaving at the end of surgery.
- AZT—Zidovudine, lamivudine and indinavir should be given for the health workers following exposure of susceptible area to infected material from AIDS patient.
Question.24. Write short note on HIV.
Or
Write briefly on HIV.
Answer. HIV means human immunodefiiency virus.
- HIV was discovered in 1983 and first case was detected in UK
- It was discovered by Barre-Sinoussi and Montagnier
- HIV virus is classifid under HTLV-III
- HIV is of two types, i.e. HIV-1 and HIV-2 which are the retroviruses.
Mode of transmission of HIV
- Sexual intercourse either vaginal or anal.
- Needle pricks, i.e. using unsterilized needles for injections,In IV drug abusers, careless handling
- Mother to child: During birth through vaginal secretion,transplacental, through breast milk
- Through blood transfusions and organ transplantations
Pathogenesis
The envelope glycoprotein of HIV binds with surface molecules of CD4 cells of T-lymphocytes, monocytes, macrophages,
- Langerhans cells and dendritic cells of all tissues.
- CD4 of lymphocytes and T helper cells control normal immune response.
- HIV suppresses immune response completely suppressing B-cell.
- Finally, it dismantles and destroy immune system making the individual prone to opportunistic infections.
Clinical Classification of HIV
- Acute infections
- Asymptomatic but positive HIV.
- Persistent generalized lymphadenopathy
- AIDS (HIV-related diseases):
- Constitutional diseases such as weight loss, fever,diarrhea
- Neurological diseases such as dementia, neuropathy, myelopathy
- Opportunistic infections
- Malignancies: Kaposi’s sarcoma, non-Hodgkins lymphoma
- Other diseases attibutable to HIV infection.
Test For HIV
- ELISA test (Screening test)
- Western blot (Diagnostic test)
- Polymerase chain reaction
- Anti-HIV antibody reaction
- Viremia quantification—to start the treatment and to see the response of anti-viral drugs.
- CD4 cell count:
- Normal value > 500/mm3
- Values between 200 to 500/mm3 is seen in Kaposi’s sarcoma, Candida infection and M. tuberculosis
- Values between 50 to 200/mm3 is seen in Pneumocystis carinii and Toxoplasma infection
- Values< 50/mm3 is seen in atypical mycobacteria,cytomegalovirus and lymphomas.
After the HIV infection, there is time gap for the patient to become reactive to tests. This time is known as “Window period”.
This period is variable and during this period an individual is infective.
Treatment Of HIV
- Antiviral therapy or HAART therapy
Nucleoside reverse transcriptase inhibitor (NRTI): Zidovudine,didanosine, abacavir, lamivudine, stavudine.
Non-nucleoside reverse transcriptase inhibitor (NNRTI): Nevirapine, delavirdine.
Protease inhibitors: Ritonavir, indinavir, amprenavir. - Treatment of opportunistic infections.
- Treatment of tumors.
- Immunotherapy:
Alpha and gamma interferons.
Interleukins. - Bone marrow transplantation.
- Anti-CD3 or IL-2 after HAART (Highly Active Anti- Retroviral Therapy).
- Psychotherapy
- Counseling of HIV patients and their families.
- Life expectancy after initial HIV infection is 8–l0 years.
Question.25. Describe the mode of spread of HIV. Describe treatment.
Answer.
Mode of Spread of HIV
- Sexual intercourse either vaginal or anal.
- Needle pricks, i.e. using unsterilized needles for injections,In IV drug abusers, careless handling
- Mother to child: During birth through vaginal secretion, transplacental, through breast milk
- Through blood transfusions and organ transplantations
Treatment Of HIV
- Antiviral therapy or HAART therapy:
- Nucleoside reverse transcriptase inhibitor (NRTI): Zidovudine,didanosine, abacavir, lamivudine, stavudine.
- Non-nucleoside reverse transcriptase inhibitor (NNRTI): Nevirapine, delavirdine.
- Protease inhibitors: Ritonavir, indinavir, amprenavir.
- Treatment of opportunistic infections.
- Treatment of tumors.
- Immunotherapy:
- Alpha and gamma interferons.
- Interleukins.
- Bone marrow transplantation.
- Anti-CD3 or IL-2 after HAART (Highly Active AntiRetroviral Therapy).
- Psychotherapy
- Counseling of HIV patients and their families.
- Life expectancy after initial HIV infection is 8–l0 years.
Question.26. Describe the nosocomial infection.
Answer. It is an infection acquired due to hospital stay.
Sources
- Contaminated infected wounds.
- Urinary tract infections.
- Respiratory tract infections.
- Opportunistic infections.
- Abdominal wounds with severe sepsis.
- Spread can occur from one patient to another, through
nurses or hospital staf who fail to practice strict asepsis.
It is more common in:
- Diabetics
- Immunosuppressed individuals
- Patients on steroid therapy and life-supporting machines
- Instrumentations (including catheter, IV cannulas,tracheostomy tube)
- Patients with artifiial prosthesis
Organisms
- Staphylococcus aureus is the most common organism causing hospital-acquired wound infection. Others are Pseudomonas, Klebsiella, E. coli, Proteus.
- Streptococcus pneumoniae, Haemophilus, Herpes, Varicella,Aspergillus, Pneumocystis carinii are the most common pathogens involved in hospital-acquired respiratory tract infection which spreads through droplets.
- Klebsiella is the most common pathogen involved in hospital acquired UTI which is highly resistant to drugs.
Management
Most of the time, organisms involved are multidrug-resistant, virulent, and hence, cause severe sepsis.
- Antibiotics.
- Isolation.
- Blood, urine, pus for culture and sensitivity to isolate the organisms.
- Blood transfusion, plasma or albumin therapy.
- Ventilator support.
- Maintaining optimum urine output.
- Nutritional support.
Prevention
- Isolation of patients with badly infected open wounds.
- Severe RTI/UTI.
- Following strict aseptic measures in OT and in ward by hospital attndants.
- Proper cleaning and use of disinfectant lotions and sprays for bedpans, toilets and flor.
- The precipitating causes have to be treated, along with caring for proper nutrition and improving the anemic status
by blood transfusion.
Question.27. Name the etiological agent, pathognomic diagnostic feature and treatment (only modalities) of actinomycosis.
Answer.
Etiological Agent
It is caused by Actinomyces israelii
Pathognomic diagnostic Feature
Multiple discharging sinuses which discharge sulphur granules and there is no lymph node enlargement present.
Treatment (only modalities)
- Antibiotic therapy
- Excision of sinuses
- Actinomycosis of right iliac fossa should undergo hemi colectomy
Question.28. Name etiological agent, pathognomic diagnostic feature and treatment (only modalities) of anthrax.
Answer.
Etiological Agent
Anthrax is caused by Bacillus anthracis
Pathognomic diagnostic Feature
After 3 to 4 days of incubation an itching erythematous papule develop on exposed portion of body, i.e. hand, forearm, etc.
The papules suppurate and form black slough. This lesion is surrounded by vesicles known as malignant pustule.
Treatment (only Modality)
Antibiotic therapy is given.
Question.29. Name etiological agent, pathognomic diagnostic feature and treatment (only modalities) of chancre.
Answer.
Etiological Agent
It is caused by Treponema palladium
Pathognomic diagnostic Feature
A shallow, painless, indurated, non-bleeding ulcer seen on genitalia, lips, breasts and anal region, this is known as Hunterian chancre.
This is confirmed by dark-field microscopic study of discharge for organism.
Treatment (Modality only)
Antibiotic therapy should be given.
Question.30. Write short note on septicemia.
Answer. Presence of overwhelming and multiplying bacteria in blood with toxins causing systemic inflammatory response syndrome or multiorgan dysfunction syndrome.
Clinical Features
- Intermittent high-grade pyrexia (fever)
- Rigors and chills.
- Jaundice due to liver damage.
- Peripheral circulatory failure.
- Intravascular coagulation.
- Patient may go into septic shock.
- Septic shock is secondary to sepsis; it is characterized by inadequate perfusion of tissue.
- The septic shock diffrs from all other forms of shock by having hot stage before cold stage.
Types
- Gram-positive septicemia: It is due to staphylococci, streptococci, pneumococci, etc. It is common in children, old age.
diabetics and after splenectomy. Common origin is skin,respiratory infection - Gram-negative septicemia is common in acute abdomen such as peritonitis, abscess, urinary infections, biliary infections,postoperative sepsis.
It is commonly seen in malnutrition,old age, diabetics, immunosuppressed people.
Common focus of infection is gram-negative infection is urinary infection, abscess or infected wounds, biliary sepsis, post operative wounds.
Investigations
- Urine/pus/discharge culture
- Blood culture
- Hematocrit
- Electrolyte assessment PO2 and CO2 analysis
- Blood urea, serum creatinine, liver function test
Complications
- Disseminated intravascular coagulation
- Acute respiratory distress syndrome
- Liver dysfunction
- Renal failure
- Bone marrow suppression-thrombocytopenia
- Multiorgan failure
Treatment
- Antibiotics such as cefoperazone, ceftazidime, cefotaxime,amikacin, tobramycin, metronidazole.
- Fresh blood transfusion.
- Adequate hydration.
- Oxygen supplementation.
- Ventilatory support.
- Electrolyte management.
- Parenteral nutrition
- CVP line for monitoring and perfusion.
- Fresh-frozen plasma or platelets in disseminated intravascular coagulation
Question.31. Write short note on septicemia, toxemia and pyaemia.
Answer. For septicemia, refer to Ans 32 of same chapter.
Toxemia
Distribution throughout the body of poisonous product of bacteria growing in a focal or local site, thus producing generalized symptoms such as: fever, diarrhea, vomiting.
Clinical Features
- Intermittent high-grade pyrexia (fever)
- Rigors and chills.
- Jaundice due to liver damage.
- Peripheral circulatory failure.
- Intravascular coagulation.
- Patient may go into septic shock.
- Septic shock is secondary to sepsis; it is characterized by inadequate perfusion of tissue.
- The septic shock diffrs from all other forms of shock by having hot stage before cold stage.
Treatment
- Management of primary focus of infection.
- Broad-spectrum antibodies are given.
- Blood and flid transfusion to correct septic shock.
- Injection of hydrocortisone in case of septic shock may be useful.
Pyaemia
Presence of multiplying bacteria in blood as emboli which spread and lodge in diffrent organs in the body like liver, lungs,kidneys, spleen, brain causing pyaemic abscess.
This may lead to multiorgan dysfunction syndrome (MODS). It may endanger life, if not treated properly.
Clinical Features
- Fever with chills and rigors
- Jaundice, oliguria, drowsiness
- Hypotension, peripheral circulatory collapse and later coma with MODS
Common Causes
- Urinary infection (most common)
- Biliary tract infection.
- Lower respiratory tract infection.
- Abdominal sepsis of any cause.
- Sepsis in diabetics and immunosuppressed individuals such as HIV, steroid therapy.
Investigations
- Total leucocyte count, platelet count
- Biliary tract infection
- Pus, blood and urine culture depending on the need.
- Blood urea, serum creatinine
- Liver function tests, prothrombin time
- Chest X-ray, USG abdomen
- CT chest/abdomen/brain as needed
- Arterial blood gas analysis, if needed
Treatment
- Monitoring of vital parametres
- Antibiotics mainly cephalosporins
- IV flids and maintenance of urine output.
- Hydrocortisone
- Blood and plasma transfusion
- Nasal oxygen, ventilator support, monitoring of pulmonary function.
Question.32. Describe differentiating features of septicemia and pyemia
Answer. Following are the differentiating features of septicemia and pyemia:
Question.33. Describe differentiating features of bacteremia and septicemia.
Answer
Question.34. Differentiate between Gram-negative and Gram-positive septicemia and management.
Answer.
Management of Gram-Positive and Gram-negative septicemia
- Correction of flid and electrolyte by crystalloids, blood transfusion. Perfusion is very/most important.
- Appropriate antibiotics—third generation cephalosporins/aminoglycosides.
- Treat the cause or focus—drainage of an abscess;laparotomy for peritonitis; resection of gangrenous bowel;wound excision.
- Pus/urine/discharge/bile/blood culture and sensitivity for antibiotics.
- Critical care, oxygen, ventilator support, dobutamine/dopamine/noradrenaline to maintain blood pressure and urine output.
- Activated C protein prevents the release of inflmmatory mediators and blocks the effcts of these mediators on cellular function.
- Monitoring the patient by pulse oximetry, cardiac status,urine output, arterial blood gas analysis.
- Short-term (one or two doses) high-dose steroid therapy to control and protect cells from effcts of endotoxemia.
It improves cardiac, renal and lung functions.
Single dose of methylprednisolone or dexamethasone which often may be repeated again after 4 hours is said to be effctive in Gram-negative septicemia.
Question.35. Write short answer on Australian antigen.
Answer. A scientist named Blumberg and his coworkers in 1965 describe a protein antigen in serum of an Australian aborigine which gave positive precipitation reaction with sera from two hemophiliacs who had received multiple transfusions.
This antigen was named as Australian Antigen.
1. HBsAg is known as AustraliaAntigen and was established to be the surface component of hepatitis B virus.
2. Australian antigen consists of two diffrent antigenic determinants i.e.
- A group specifi antigenic determinant a
- wo pairs of type specifi antigens d y and w r. In these only one member ofeach pair is present at a time.
3. Australia antigen on the basis of type specifi pairing is divided in four types i.e.
- adw is worldwide in distribution
- adr in Asia
- ayw in Africa, India, Russia
- ayr in Africa, India, Russia
4. Various additional surface antigens i.e. q, x, f, t, j, n and g are described, but their characterization is not done.
Electron microscopy of serum of hepatitis B patients show three types of particles, i.e.
- Spherical particle: It is most abundant and is 22 nm in diameter.
- Tubular particle: It is of varying length and is 22 nm in diameter.
- Dane Particle: It is double sheilded spherical structure which is 42 nm in diameter. This particle is complete hepatitis B virus.
5. The spherical and tubular particles are antigenically identical and are surface subunits of hepatitis B virus Australia antigen (HBsAg).
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