Nosocomial Infections

Nosocomial Infections

Infections which are acquired from hospitals are called nosocomial infection. These infection occurring with in 48 hours of hospital admission, 3 day of discharge or 30 days of an operation. If the organisms come from another patient it is called cross infections and if patient himself carries the infection to some other site then it is autoinfection. Infection may become apparent during the stay of the patient in the hospital or after his discharge from the hospital. There is actual increase in frequency and severity of infection especially due to antibiotic resistant enterobacteria, Staphylococcus aureus and Pseudomonas aeruginosa.Thus prolonged stay of the patient in the hospital is undesired and may be a serious matter for the patient and his family.

Patients Requiring Isolation:

Some patients really need isolation. Patients of tuberculosis, typhoid, diphtheria, lassa fever or smallpox should not be treated or nursed in open ward as these disease are serious and easily transmissible. Similarly infants with measles or whooping cough should not be nursed in general ward but may be treated at home. Staphylococcus aureus infection cases especially resistant to many antibiotics belonging to phase types (80/81 or 75/77) capable of causing serious epidemic of hospital sepsis, certainly require isolation. Isolation cubicles are suggested for these purposes which should be so designed, equipped and managed that no microorganism can pass from them to a ward. Attendant should use gown on entering the cubicle and remove on leaving. Washing facilities for the patient and attendant of the patient must be provided in the cubicle. Dressing should be discarded into paper bags which may be removed to incinerator. Bedding and clothing should be kept in disinfectant solution before sending to laundry. When the patient finally leaves the cubicle,it must be thoroughly washed with disinfectant and all equipment must be sterilized as far as possible.

Hospital Infection and Prevention:

We should be aware of some important hospital infections and their prevention:

1. Wounds and burns: It is important to remove all tissue debris from accidental wounds and burns as bacteria can establish more easily in damaged tissue. A careful and aseptic technique for dressing of wound preferable in dressing room reduces chances of cross infection.
2. Urinary tract infection: Catheter or other instruments into the bladder may cause urinary tract infection. Used catheters are difficult to sterilize and may be the cause of cross infection also, hence disposable sterilized catheter should be used aseptically.
3. Alimentary tract infections: Outbreak of E.coli gastroenteritis in children and Shigella sonnei, dysentery do occur quite oftenly  in hospital. Isolation, general hygiene and exclusion of carriers are important preventive measures.

Epidemiological Markers Useful in investigating Hospital Infection:

• Antibiogram and resistogram.
• Biotyping.
• Phage typing.
• Bacteriocin typing.
• Serotyping.
• Serum opacity factor.
• RNA electropharesis as in done in rotavirus.
• Cytotoxicity assay, e.g. Proteus mirabilis.
• Plasmid profile.

Prevention of Nosocomial Infections:

• Proper washing
• Isolation of patients, e.g. plague, influenza, measles, etc.
• Careful and appropriate use of instruments.
• Use of antibiotics only if required. It may be given to carrier staff or patient.
• Use of blood transfusion only if must. Disinfectants of excreta and infected material.
• Surveillance of infection properly and regularly.
• Use of vaccine, e.g. tetany gas sangrene, hepatitis – B, etc.

Factors Responsible for Hospital Infections:

• Neonates and aged patients have risk of getting hospital infection because of long stay and decreased immunity.
• Impaired defense mechanisms of patients due to disease or treatment.
• Hospital environment contains relatively heavy load of microorganisms.
• Major invasive diagnostic or therapy procedures.
• Advance treatment of cancer, organ transplantation, etc.
• Presence of multidrug resistant bacteria, etc.

Source of Hospital Infection :

• Infecting microorganisms from fellow patients which may be multidrug resistant.
• Infected organisms from hospital staff
• Infecting organisms from instruments, blood products, intravenous fluid, etc.
• From patient’s normal flora, etc.
• Insects are also source multidrug infection.
• Organism may be present in air, dust, water, antiseptic solution, food, etc.
• Surface contaminated by patient’s secretions, blood fluid, etc.

Mode of Infection :

• Airborne.
• Contact, e.g. hand, clothing, etc.
• Food and water.
• Hospital equipments and instruments.
• By parenteral routs.