Infection Question And Answers

Infection

Question 1. What are opportunistic infections? How can these infections be avoided in clean and safe surgery?
Answer:

Opportunistic infection occurring in patients with AIDS or another debilitating disease such as cancer, diabetes or when the physiological state has been upset by immunosuppressive drugs, steroids, X-ray or broad spectrum antibiotics.

• Caused by fungi, this is normally a virulent, for example Aspergillus, mucor, penicillium.
• The most common human disease caused by aspergilli is otomycosis.
• Penicillium species have been very rarely incriminated in opportunistic human infections.
• Penicillium marneffei has been reported to be an important opportunistic pathogen in HIV-infected person.

Read And Learn More: Microbiology Question And Answers

• Infections are avoided in clean and safe surgery by the following means:
  • During surgery, the equipment used should be sterilized properly.
  • Before surgery, the place should be get disinfected by using certain disinfectants.
  • The doctor performing the surgery should use aseptic measures for himself and for the patient so that infection might not occur.
  • Following measures are to be taken by doctor before performing surgery.
    1. He/she should wear sterilized gloves.
    2. He/she should wear sterilized gown and sleepers.
    3. He/she should use well-sterilized mouth mask before going for surgery.
  • Following measures to be taken by patient before going for surgery:
    1. Patient should wear sterilized gowns.
    2. Disinfection of the patient’s skin should be carried out before going for surgery to obtain clean and safe surgery.
    3. The surface on which the surgery is to be manifested should be free of microorganisms.

Question 2. Write a note on modes of transmission of infection giving an example of each.
Answer:

Infection is the lodgement and multiplication of organisms in the tissue of host.

Modes of Transmission of Infection:

•  Contact:  Various infections are spread by the contact. Most common contact, i.e. direct contact is through sexual pathway. The diseases spread by direct contact are syphilis, gonorrhea, etc. Indirect contact can occur through fomites which are inanimate objects such as clothing, pencils, e.g. diphtheria and trachoma.
• Inhalation: Infection through inhalation spreads via the nasal passage, for example, influenza, tuberculosis, smallpox, etc. In inhalation the microbes are shed by patient in the environment via secretion from nose or throat at the time of sneezing, speaking or coughing.
• Inoculation: Infection spread through the tissues of host. Infectious by inoculation may be iatrogenic. When unsterilized syringes and equipment are used. For example, tetanus, hepatitis B, HIV, etc.
• Insects: They act as mechanical vector or biological vectors of infectious disease, e.g. dysentery and typhoid by housefl, malaria by mosquito, etc.
•  Congenital: Some of the pathogens cross the placental barrier and infect fetus in utero. This is known as vertical transmission. This may lead to abortion. Infections spread congenitally and infants may be born with manifestation of disease, e.g. are congenital syphilis, rubella, etc.
• Laboratory or Iatrogenic infection: In the absence of proper care, infection may be transmittd during procedure like injection, lumbar puncture, catheterization, etc. then the various modern methods of treatment such as dialysis, organ transplant surgery, etc. have increased the possibilities of iatrogenic infections.

Question 3. Write a short note on bacterial virulence.
Answer:

Virulence is referred to the ability of microbial strains to produce disease, e.g. Polio virus contains strain of varying degree of virulence.

Virulence is the Sum of the following Factors:

• Adhesion: This is the attachment of the bacteria to body sur- face via adhesive structures known as adhesins.
• Invasiveness: It is the ability of organisms to spread in a host tissue after establishing infection.
• Toxigenicity: Bacteria products exotoxins and endotoxins which cause fever, muscle proteolysis, and shock.
• Communicability: It is the ability of a parasite to spread from one host to another. It determines survival of parasite in a community.
• Other bacterial products: The other bacterial products are coagulase, fibrinolysin, hyaluronidase, hemolysin, etc. Though devoid of intrinsic toxicity may contribute to virulance by inhibiting mechanisms of host resistance.
• Bacterial appendages: Certain bacteria withstand phagocytosis, example,  Streptococcus pneumoniae, Haemophilus inflenzae etc.
•  Infecting dose: The minimum infection or minimum lethal dose is minimum number of organisms required to produce death of susceptible animal.
• Route of infection: Various microbes produce infection through various routes, for example, cholerae is effctive orally.

Question 4. Write the difference between exotoxins and endotoxins.
Answer:

Question 5. Write a note on methods of prevention of infections and infectious diseases in the community.
Answer:

Methods of Prevention of Infections:

• Safe drinking water: Drinking water is usually purified and rendered suitable for human consumption by a combination of sedimentation, chlorination, and filtration.
• Safe food chain: Infections contracted from animals could theoretically be prevented at the source by avoiding contact with animal concerned.
• Action against vectors of disease: Many diseases are transmitted by either living or inanimate vectors. Insects play an important role in the transmission of infectious disease in warm climates. Eradication of an insect vector or preventing its contact with human body is an effective way of preventing infection.
• Individual and professional hygiene: For effective prevention education of every member in community in basic preventive methods including personal lavatory hygiene, food preparation and storage techniques as well as responsible sexual behavior.
• Vaccination: It provides immunity to the body. Vaccination should take place before exposure to the infective agent for allowing the development of protective immunity.
• Chemoprophylaxis: Antimicrobial agents are used for prevention. They do not eliminate infection at the source but interfere with the invasion of sterile tissues and secondary spread.

Infectious Diseases in the Community:

They are classified as:

• Endemic: Disease which is constantly present in a particular area, i.e. enteric fever.\
• Epidemic: A disease which spreads rapidly involving many individuals in a particular area at the same time, this is known as epidemic disease, for example. meningococcal meningitis.
• Pandemic: It is the epidemic that spreads to many areas of the world involving the large number of persons in a short period of time, for example, cholera, influenza, etc.
• Sporadic: A few scattred cases which occur in lateral part of an epidemic when the virulence of an organism is lowand resistance of the population is high.
• Prosodemic: It is an epidemic disease which is smoldering and is often transmitted from person to person chiefl by contact.

Question 6. Write in details the classification and modes of transmission of various infectious diseases by giving examples.
Answer:

Classifiation of Infections:

• Primary infection:  This is the initial infection with a parasite inside the host and is known as primary infection.
• Reinfection: Subsequent infection with the same parasite in same host is known asreinfection.
• Secondary infection: When the resistance of body become low to preexisting infectious disease a new parasite leads to new infection. This is known as a secondary infection.
• Cross infection: When patient already suffring from a disease acquire new infection from another host or other external source. This is known as cross infection.
• Nosocomial infection: Cross infection which is acquired from the hospitals this is known as nosocomial infection.
• Latrogenic infection: It is defied as physician induced infection which occurs from drug therapy or investigative procedures.
• Subclinical infection: When the clinical symptoms of infection are not apparent, this is known as subclinical infection.
• Latent infection: Following the infection some parasites may remain in latent form in host tissues and they proliferate and produce clinical disease when the host resistance is lowered. This is known as latent infection.
• Atypical infection: In this the typical or characteristic clinical manifestations of particular infectious disease are not present.

Mode of Transmission:

1. Contact

• Contact can be direct or indirect:
  • Direct contact: Sexually transmitted diseases such as syphilis, gonorrhea, and AIDS are acquired by direct contact.
  • Indirect contact: It can be via the agency of fomites which are inanimate objects, i.e. clothes, toys which can be contaminated by a pathogen and act as vehicle for transmission, e.g. face towels shared by multiple persons can lead to trachoma.

2. Inhalation:

Various respiratory infections, for example,  common cold, whooping cough, inflenza and tuberculosis are acquired by inhalation. Organisms leading to above diseases shed in the environment by patients via the secretion from nose or throat at the time of coughing, sneezing and speaking. Large drops of these infections fall in ground and dry there. Small droplets less than 0.1 mm in diameter evaporate and become droplet nuclei which suspend in air and become the source of infection.

3. Ingestion:

Infections such as cholera, food poisoning and parasitic infections are acquired by ingestion of contaminated food or drink. Food borne infections occur through the carriers which get engaged in handling or preparation of food. Water supply gets contaminated by feces of patients. These can transmit infection.

4. Inoculation:

Pathogens at times can inoculated directly inside the tissues of the host, for example, rabies virus is inoculated directly by bite of dog. Infection by inoculation can be iatrogenic when unsterile syringes and equipment are used. HIV and hepatitis B can be caused by transfusion of infected blood.

5. Vectors:

Insect act as vectors and transmit infections from one person to another. Transmission is of two types, i.e. mechanical and biological.

• Mechanical transmission is through direct transmission without the development of microorganisms with the help of legs, wings or body, for example, is dysentery and typhoid by houseflies
• Biological transmission during which there is the development of pathogen in the body of insect, e.g. transmission of malaria by a mosquito.

6. Transplacental:

Some of the pathogens cross the placental barrier and infect fetus in utero. It is also known as vertical transmission, example. congenital syphilis live infants born with the manifestation of disease, example. pathogens such as T. pallidum, HIV, rubella virus, plasmodium spp. are able to cross the placental barrier.

7. Latrogenic and Laboratory Infections:

If during asepsis proper care is not given various infections such as AIDS and hepatitis B can be transmittd during diagnostic procedures, i.e. injections, lumbar puncture, blood transfusion, dialysis, etc. All such infections are known as iatrogenic infections. Laboratory persons who handle infectious material are at risk.