NOSOCOMIAL INFECTIONS

Eligius Lyamuya MD, MMed, PhDDepartment 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 infectionPre-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 treatmentselective 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

• ExogenousAnother person (cross-infection)Contaminated items (environmental

infection)

• EndogenousFrom patient’s own skin, GIT or URT flora

(self-infection)

TRANSMISSION: Routes

• Airborne From the respiratory tract through talking,

sneezing, coughingFrom skin by natural shedding of skin scales, wound

dressing, bed makingBy aerosols from equipment eg. Respiratory

apparatus and air conditioning plant

• ContactDirect from person to person Indirect via contaminated hands or equipmentContaminated “sharp” injury

Commonly occurring microorganisms in hospital infection

Bacteria Viruses FungiS. aureus HIV Candida albicans

E. coli HBV

Klebsiella HCV

Pseudomonas CMV

Coagulase negative staphylococci

VHF viruses

Proteus

Anaerobes

Others

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

guidelinesRegular 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 methodSharp 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 controlPeri-operative prophylaxis vs anaerobes in GIT and

Gyn surgeryUrological 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:GownApronFace masksGlovesHeadgearGogglesBoots

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.