Hospital Acquired Infection, Biomedical Waste, Needle Stick Injury, Environmental Surveillance

Hospital Acquired Infection, Biomedical Waste, Needle Stick Injury, Environmental Surveillance

Hospital Acquired Infections

Hospital-acquired infections or nosocomial infections can be defined as the infections acquired in a hospital by a patient:

• who was admitted for a reason other than that infection
• in whom the infection was not present or incubating at the time of admission
• symptoms should appear at least after 48 hours of admission
• This includes infections acquired in the hospital but appearing after discharge, and also occupational infections among staff of the hospital care facility.

Read And Learn More: Micro Biology And Immunology Notes

Microorganisms Implicated in HAIs

ESKAPE pathogens—They are the multidrug-resistant isolates present in a hospital, such as Enterococcus faecium, Staphylococcus aureus, Klebsiella pneumoniae, Acinetobacter baumannii, Pseudomonas aeruginosa, Enterobacter species Other common infections that can spread in hospitals include:

• Escherichia coli, Nosocomially acquired M. tuberculosis, Legionella pneumophila, Candida albicans
• Clostridium difficile diarrhea
• Blood-borne infections (BBIs) transmitted through contaminated needle prick injury or mucocutaneous exposure of blood include- HIV, hepatitis B, and C viruses.

Types of HAIs

In any hospital, the four most common HAIs encountered are UTI (33%), Pneumonia (15%), Surgical site infections (15%), and Bloodstream infections (13%)

Prevention of HAIs

Standard (Routine) Precautions

Standard precautions are a set of infection control practices used to prevent transmission of diseases that can be acquired by contact with blood, body fluids, non-intact skin (including rashes), and mucous membranes
Components of standard precautions include (indicated while handling all patients, specimens,and sharps):

• Hand hygiene
• Personal protective equipments (PPEs): Gloves, mask, gown, shoes, eye cover
• Spillage cleaning by 10% sodium hypochlorite
• Disinfection usage
• Waste handling and sharp handling: All sharps should be handled with extreme care.

Hand Hygiene

Hand hygiene is the most important measure to avoid the transmission of HAIs. Types of hand hygiene methods available:

• Hand rub: Alcohol (70–80% ethyl alcohol) plus chlorhexidine (2–4%) based hand rubs is ideal. The duration of contact has to be at least for 20–30 seconds.
• Advantage: After a period of contact, it gets evaporated of its own hence drying of hands is not required separately.
• Indications (Five Moments of Hand Hygiene, WHO): Hand rub should be done in the FIVE situations/moments during routine round in ward or ICU, such as: (1) Before touching the patient, (2) Before an aseptic procedure, (3) After an aseptic procedure/body fluid exposure risk, (4) After touching the patient, (5) After touching the patient’s surrounding.
• Handwash: Antimicrobial soaps (liquid, gel, or bars) are available. Duration of contact has to be at least for 40–60 seconds. Handwashing is indicated in the following situations:
  • When the hands are visibly soiled with blood, excreta, pus, etc.
  • Before and after eating
  • After going to toilet
  • Before and after shift of the duty.

Specific Precautions

Additional precautions are needed for preventing specific modes of transmission, such as Airborne precautions, Droplet precautions and Contact precautions.

HAI Surveillance

The Hospital Infection Control Committee (HICC) maintains surveillance of hospital-acquired infections. The four key parameters used for HAI surveillance are:

• CA-UTI (Catheter-associated urinary tract infection)
• CLABSI (central line-associated bloodstream infection)
• VAP (ventilator-associated pneumonia)
• SSI (surgical site infections).

Biomedical Waste Management

Biomedical Waste Management in India is followed according to New BMW Rule 2016. The earlier 1998 BMW rule is obsolete now.

Needle Stick Injury

An occupational exposure is defined as:

• Percutaneous injury [e.g. needle stick injury (NSI) or other sharp injury]
• Splash injury:
  • Contact with the mucous membrane (e.g. eye or mouth);
  • Contact with non-intact skin (abraded skin or afflicted with dermatitis);
  • Contact with the intact skin when the duration is prolonged (e.g. several minutes or more).

Transmission Risk

The transmission risk following needle stick injury is highest for hepatitis B (6-30%) followed by hepatitis C (3%) and HIV (0.3%).

Steps of Post-Exposure Management

1. First aid: Immediately wash the wound and surrounding skin with water and soap and rinse. Don’t put finger in mouth or do not squeeze finger.
2. Report to designated nodal centre
3. Take first dose of PEP for HIV within 2 hours of exposure
4. Laboratory testing for blood-borne viruses such as HIV, HBV and HCV
5. Decision on PEP for HIV and HBV (Tables 7.2.3 and 7.2.4)
6. Documentation and recording of exposure
7. Informed consent and counselling
8. Follow-up testing of HCWs:
   • For HIV testing, the follow-up is done at 6 weeks, 3 months and 6 months after exposure.
   • For HBV and HCV testing, the follow-up is done at 6 months after exposure.
9. Precautions during the follow-up period: If the source status is positive/unknown, then the following precautions should be adopted by the HCW during the follow-up period,especially the first 6–12 weeks.
   • Refraining from blood, semen, organ donation
   • They should also be counselled on safe sexual practices (latex condom) till both baseline and 3 months HIV test are found to be negative.
   • Women should not breastfeed their infants.
   • The exposed person is advised to seek medical evaluation for any febrile illness that occurs within 12 weeks of exposure.

Environmental Surveillance (Air, Water, And Surface)

Bacteriology of Water

Methods of Water Analysis

• Presumptive coliform count (Multiple tube method): This detects the probable number of coliform bacilli in water.
• It is done by calculating as the most probable number (MPN) of coliform organisms in 100 ml water
• Medium: MacConkey purple broth (double strength and single strength) in is the standard medium of choice
• Detection of coliform bacteria does not always indicate fecal contamination as some of them may be found in environment. Hence, it is further tested by differential coliform count to detect the fecal E. coli.
• Eijkman test: It is done to confirm that the coliform bacilli detected in the presumptive test are fecal thermo tolerant E.coli which grows at 44 °C with indole and gas production and lactose fermentation. Brilliant green bile broth is used.

Other methods

• Clostridium perfringens detection
• Enzyme detection: β galactosidase (coliform bacilli specific enzyme) and β glucuronidase (fecal E. coli specific)
• Membrane filtration method
• Examination for specific water-borne pathogens such as Salmonella typhi and Vibrio cholerae

Bacteriology of Milk

Methods for Bacteriological Examination of Milk

• Colony count: Viable count (by plate dilution method) and Coliform count
• Chemical tests:
  • Methylene blue reduction test (more economical)
  • Phosphatase test (test the effectiveness of pasteurization of milk)
  • Turbidity test (definitive test for checking the sterilization of milk)
• Detection of specific pathogens such as Tubercle bacilli and Brucella.

Bacteriology of Air

Methods for measuring bacterial content of air- fall into two broad categories.

• Settle plate method-measure bacteria carrying particles settle down by gravity from air on to the exposed surface
• Slit sampler method and air centrifuge method: Count the number of bacteria-carrying particles in a given volume of air.