Sore Throat
Question 1. Write a short note on a sore throat.
Answer:
Sore throat is an acute tonsillitis and/or pharyngitis. Sore throat is characterized by redness and edema of the mucosa, exudation of tonsils, pseudomembrane formation, and enlargement of cervical lymph nodes.
Etiological Agents Of Throat
The following agents lead to sore throat:
- Bacteria:
- Streptococcus pyogenes
- Corynebacterium diphtheriae
- Staphylococcus aureus
- Beta-hemolytic streptococci—Group C and G
- Borrelia vincentii
- Neisseria gonorrhoeae
- Mycoplasma pneumonia
- Fusobacterium spp.
- Fungus:
- Candida albicans.
- Virus:
- Adenovirus
- Influenza virus
- Para influenza virus
- Coxsackie virus.
- Rhinovirus
- Coronavirus
- Respiratory syncytial virus
Read And Learn More: Microbiology Question And Answers
Pathogenesis of Throat: Infection occurs by droplet inhalation, and the portal of entry is the respiratory tract.
Clinical Features of Throat
- Fever
- Pain of swallowing
- Dysphagia
- Tonsillitis
- Pharyngitis
- Painful cervical lymphadenopathy
Laboratory Diagnosis of Throat
- Direct Microscopy:
- Gram stain: This staining method is useful only in the demonstration of Vincent’s organism and Candida albicans. When staining with Gram stain is done Borrelia vincenti appear as gram-negative spirochaete and Fusiform bacilli appear as gram-negative bacilli. Candida appears as a gram-positive oval budding yeast cell.
- Albert staining: It is useful in the presumptive diagnosis of C. diphtheriae. Bacilli appear as green-colored and V or L-shaped bacilli with bluish-black metachromatic granules.
- Culture: Following are the media that are used for the culture
- Blood agar: All organisms can grow on this medium.
- Crystal violet blood agar: Selective medium for S. pyrogens S. pyrogens appear as pinpoint, round, or convex colonies with entire margins with β-hemolysis.
- Potassium tellurite blood agar: Selective medium for growing C. diphtheriae. It appears as black-colored round colonies.
- Sabouraud’s dextrose agar: It is used when Candida is suspected. Candida appears as a white, colored or cream-colored colony. The above media are incubated at 37 °C for overnight. In the case of potassium tellurite blood agar incubation is done for 48 hours.
- Identification:
-
- S. pyogenes: It is seen as pinpoint, round or convex colonies with entire margin with β-hemolysis.
- C. diphtheriae: On potassium tellurite blood agar it is seen as black-colored round colonies.
- Candida albicans: It appears as white or cream-colored colonies.
-
Meningitis
Question 2. Write briefly on meningitis.
Answers:
Meningitis is the inflammation of the membrane surrounding the brain and spinal cord. Meningitis is caused by viruses, bacteria, fungi, and protozoa.
Types of Meningitis
Meningitis is of two types, i.e. of bacterial origin and viral origin
- Meningitis of bacterial origin is also known as pyogenic meningitis or bacterial meningitis. In this, CSF shows a predominance of polymorphonuclear leukocytes, so it is also known as polymorphonuclear meningitis.
- Meningitis of viral origin is also known as viral meningitis or aseptic meningitis. In this, CSF shows a predominance of lymphocytes, so it is also known as lymphocytic meningitis.
Agents Causing Meningitis
1. Bacterial Agents:
- Primary pathogens:
- Neisseria meningitides
- Haemophilus influenza
- Diplococcus pneumoniae
- Other bacterial pathogens:
- Escherichia coli
- Staphylococcus aureus
- Brucella spp.
- Klebsiella spp.
- Pseudomonas aeruginosa
- Beta-hemolytic Streptococcus Group B
- Salmonella spp.
- Staphylococcus epidermidis
- Proteus mirabilis
- Mycobacteril tuberculosis
- Viral agents:
- Herpes virus
- Paramyxovirus
- Adenovirus
- Enterovirus
- Arbovirus
- Fungal agents:
- Candida albicans
- Histoplasma capsulatum
- Cryptococcus neoformas
- Blastomyces dermatitidis
- Parasitic agents:
- Entamoeba histolytics
- Naegleria spp.
- Acanthamoeba spp.
- Toxoplasma gondii
Pathogenesis Of Meningitis
Infection to the central nervous system occurs from following pathways:
- Hematogenous route: Infection-causing agent invades mucus membrane of the nasopharynx or oropharynx and reaches the bloodstream and disseminated during the course of bacteremia and viremia.
- Direct spread: This occurs via sinuses from the local focus of infection. Direct spread also occurs via the middle ear, sinus, nose, and nasopharynx.
- Invasion occurs through nerves.
Laboratory Diagnosis Of Meningitis
1. Rapid diagnostic methods:
- Direct wet preparation: Wet amount of cerebrospinal fluid is seen for cytological studies, which show dominant neutrophils in purulent or pyogenic meningitis and lymphocytes in viral meningitis. 90%
of lymphocytes and 10% of neutrophils are seen in tubercular meningitis. - Quelling reaction: It is indicated in the identification of H. influenza type b, pneumococci and meningococci.
- Gram stain: Gram staining smear of CSF sediment is used to demonstrate bacteria and cells.
- Direct immunofluorescence test: They detect antigens by using specific antibodies and fluorescent dyes.
- Countercurrent immunoelectrophoresis: In CSF, it is used to detect soluble antigens of meningococci, pneumococci, Group B streptococci, H. influenza, E. coli, etc.
- Latex agglutination test: It detects antigens in CSF in pneumococcal, meningococcal, Group B streptococcal, and H. influenza.
- ELISA: This is used to detect an antigen.
2. Culture:
- Centrifuged CSF deposit should be inoculated on blood agar, chocolate agar, MacConkey agar, and thioglycollate broth.
- A part of CSF should be mixed with an equal volume of glucose broth and is incubated for extended culture.
- One blood agar plate should be incubated anaerobically, and another blood agar plate and chocolate agar plate is incubated in a candle jar.
- Another blood agar plate and another media should be incubated aerobically at 37 °C. Incubation should be for 72 hours.
- As soon as incubation is completed, plates should be observed for growth, colony morphology is studied and each colony is reported and identified by using standard biochemical and serological procedures.
- Fungal culture: First direct microscopic examination should confirm for fungi. Now inoculate CSF over the Sabouraud’s dextrose agar, brain heart infusion agar, and other suitable media.
- Inoculate CSF on an agar plate and incubate at room temperature for 4 weeks and another set at 35 °C.
- As the incubation period gets over, it is observed for growth and positive culture should be identified by the standard techniques
Leave a Reply