Nosocomial infections

NOSOCOMIAL INFECTIONS Eligius Lyamuya MD, MMed, PhD Department of Microbiology and Immunology Muhimbili University of Health and Allied Sciences

LEARNING OBJECTIVES
Know the epidemiology of nosocomial infections
Understand the various modes of transmission of nosocomial infections
Know the various strategies for prevention and control of nosocomial infections

DISPOSITION
Overview
Epidemiology
Transmission
Prevention and control

OVERVIEW
Nosocomial infections are hospital-acquired infections
Categories:
Infections contracted and developing within hospital eg postoperative wound infection
Infections contracted in hospital but not becoming clinically apparent until after discharge
Infections contracted by hospital staff as a consequence of their occupation eg hepatitis B

EPIDEMIOLOGY: Magnitude
Magnitude of nosocomial infections in Tanzania unknown
Generally, widely believed that nosocomial infections occur in 5-10% of admitted patients
In developed countries e.g USA nosocomial infections develop in at least 5% of patients admitted to hospitals

EPIDEMIOLOGY: Risk factors
Risk factors factors:
Impaired natural resistance to infection
Pre-existing disease eg. diabetes, immunodeficiency states, etc.
Immunosuppresive therapy: cytotoxic drugs, radiotherapy etc.
Bypass of defence mechanisms of body surfaces eg. indwelling catheters, tracheostomy, etc.
Antibiotic treatment  selective pressure on microbial flora  resistant and virulent strains

EPIDEMIOLOGY: Impact
Prolongation of hospital stay
(in USA, estimated at average extension of 4 days)
Responsible for significant mortality
(in USA, directly accounts for an estimated 60,000 deaths per year)
Significantly increase health care expenditure
(in USA, adds $10 billion to the national health care expenditure)

TRANSMISSION: Sources
Exogenous
Another person (cross-infection)
Contaminated items (environmental infection)
Endogenous
From patient’s own skin, GIT or URT flora (self-infection)

TRANSMISSION: Routes
Airborne
From the respiratory tract through talking, sneezing, coughing
From skin by natural shedding of skin scales, wound dressing, bed making
By aerosols from equipment eg. Respiratory apparatus and air conditioning plant
Contact
Direct from person to person
Indirect via contaminated hands or equipment
Contaminated “sharp” injury

Commonly occurring microorganisms in hospital infection Others Anaerobes Proteus VHF viruses Coagulase negative staphylococci CMV Pseudomonas HCV Klebsiella HBV E. coli Candida albicans HIV S. aureus Fungi Viruses Bacteria

PREVENTION AND CONTROL
Establishment of infection control program
Sterilization
Aseptic techniques
Cleaning and disinfection
Skin decontamination
Safe disposal of hospital waste
Protective clothing
Prophylactic antibiotics
Isolation
Hospital building and design
Personnel welfare
Provision of safe blood
Surveillance

Establishment of infection control program
Primary role is to reduce the risk of hospital-acquired infection, thereby protecting patients, HCP and visitors
The functions of the program include: development of infection control policies and procedures, develop occupational health guidelines for HCP, surveillance, outbreak investigation, education, review of antibiotic utilization vis-à-vis organism antimicrobial susceptibility data, new product evaluation, research and consultancy in academic settings.

Sterilization
Sterilization is the destruction of all forms of life including spores
Provision of sterile instruments, dressings and fluids is of fundamental importance
Sterilization practices alone will not prevent spread of infection if there is carelessness in its use

Aseptic techniques
“ No touch” techniques coupled with strict personal hygiene is essential
These routines are rigidly laid down in operating theatre practice and may be modified as required for other procedures eg. wound dressing, catheterization etc.

Cleaning and disinfection
Cleaning is the removal of dirty. Basic cleaning is indispensable in keeping the hospital environment in good order.
Disinfection refers to elimination of all vegetative microorganisms; not bacterial or fungal spores, from an inanimate object
Disinfectants should be used according to laid down guidelines
Regular monitoring of in-use efficacy is essential.
Sodium hpochlorite recommended for disinfection of surfaces contaminated with HIV, HBV and HCV infected samples

Safe disposal of hospital waste
Type Disposal method
Sharp objects A, I
Blood and blood products C
Waste from patients with
infectious disease GIPH
Microbiological samples A, I
Pathologic tissue I
A= autoclaving; I= incineration; C= chemical sterilization;
GIPH= guidelines for Isolation Precautions in Hospitals

Skin decontamination
The ease of transfer and acquisition of microbial contaminants via the hands is an important in spread of hospital infection
Thorough hand washing after and before any procedure involving patient contact is essential.
Use of antiseptics in certain situations may also be beneficial.
Antiseptic is a substance applied to skin or living tissue that prevents or arrests growth or action of microorganisms either by inhibiting their activity or by destroying them.

Prophylactic antibiotics
Rational antibiotic prophylaxis plays an important role in infection control
Peri-operative prophylaxis vs anaerobes in GIT and Gyn surgery
Urological surgery
Widespread and haphazard use of antibiotics hastens emergence of antibiotic resistant bacteria
Need to have an antibiotic policy that limits the choice of antibiotics both for prophylaxis and management

Protective clothing
Different activities within the hospital require different degrees of protection to staff and patients
Components of protective gear:
Gown
Apron
Face masks
Gloves
Headgear
Goggles
Boots

Isolation
Source isolation is needed to prevent spread of specific infections to other patients
Protective isolation is intended to protect susceptible or immunocompromized patients from infection

Hospital building and design
Routine maintenance of hospital buildings to ensure ease of cleaning
Involve infection control team in new hospital construction, or modification of existing building
Pay special emphasis to operating theatres, kitchen, acute wards, laboratories and air-conditioning systems

Personnel welfare
Pre-service screening and immunization where indicated
Provision of PEP when required

Provision of safe blood
Pre-transfusion screening of donor blood for transfusion transmissible infections like HIV, HBV, HCV etc. is essential to make blood safe for those in need
Irradiation or heat treatment of blood products e.g. clotting factors according to standard recommendations

Surveillance
Regular laboratory testing of appropriate specimens to generate data that will alert infection control team to unusual clusters of infection or to the sporadic appearance of microorganisms that may present a particular infection risk or management problem
Bacterial typing schemes, antibiograms etc.

Nosocomial infections

by BRUNO THADEUS

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