Nosocomial infection ll Modes of transmission ll FON ll Important for semester exams ll By:- NK SIR

MODES OF TRANSMISSION :-

There are four main routes of transmission of infection:-

1. Contact :-
It is the principal route of transmission of nosocomial pathogens.

Hands or clothing:
The hands of hospital staff are an important vehicle of spread of infection. There is adequate scope of transmission of microorganisms from one person to another by contact of hands and clothing's of attendants.
S. aureus and S. pyogenes are two important pathogens spread by hand contact.

Inanimate objects:-
Certain instruments (endoscope, bronchoscope, cystoscope), if not properly disinfected, may transmit pathogenic organisms' e.g. Pseudomonas aeruginosa.

2. Airborne:-

Droplets:-
Droplets of respiratory infection is transmitted by inhalation.

Dust:
Dust from bedding, floors, exudates dispersed from a wound during dressing and from skin by natural shedding of skin scales (measles, staphylococcal sepsis), may contribute in spread of infections, e.g. Pseudomonas aeruginosa, S. aureus.

Aerosols:-
Aerosols produced by nebulizers, humidifiers and air conditioning apparatus transmit certain pathogens to the respiratory tract.

3. Oral route:-

Hospital food may contain antibiotic-resistant bacteria (Pseudomonas aeruginosa, E. coli, Kiebsiella spp. and others), which may colonies the intestine and later cause infection in susceptible patients.

4. Parenteral route:-

With the introduction of disposable syringes and needles, transmission of infection by parenteral route has been infrequent. However, certain infections may be transmitted by blood transfusion or tissue donation, contaminated blood products (factor VIII) and contaminated infusion fluids. (Hepatitis B and HIV are two viruses which may be transmitted in this way).