NOSOCOMIAL INFECTIONS

Shilpa. K,Microbiology Tutor, AIMSRC

INTRODUCTIONINTRODUCTION

Nosocomial infections are the infections associated with

a hospital or health care facility

SYNONYM : Hospital acquired infection (HAI)

DEFINITION

Infections acquired by the staff or visitors to the hospital

The word nosocomial comes from the Greek word

nosokomeian meaning hospital

(nosos=disease, komeo=to take care of)

SOURCES OF HAISOURCES OF HAI Endogenous source: Organisms present as part of patient’s

normal flora may cause infection

Eg: E.coli causing urinary tract infections (self infection)

Exogenous source: Transmission of organisms from the

external environment to the patient

• another patient (cross infection)

• Food, air, water, hospital waste (inanimate environment)

• Diagnostic or therapeutic intervention (iatrogenic)

HISTORYHISTORY

• Responsible for very high mortality and morbidity since

centuries

• Semmelweiss, introduced handwashing technique

• Florence Nightingale established principles and practices of

hospital design and hygiene to reduce sepsis

• Joseph Lister introduced antiseptic surgery

• The early 20th century saw the beginning of the antibiotic era

• Antibiotic resistance to multiple agents

FREQUENCY OF INFECTION FREQUENCY OF INFECTION

• Occur worldwide and affect both developed and resource-

poor countries

• Highest frequencies reported from hospitals in

Eastern Mediterranean(11.8%)

South East Asia(10%)

European (7.7%)

Western Pacific regions(9.0%)

• In India, it is hypothesized that the rate of nosocomial

infections are 20% higher than in the developed countries

• WHO notes that the rate of nosocomial infections will

continue to rise as a result of

the increasing crowded hospital conditions

Increasing number of people with compromised

immune status

New micro-organisms

Increasing bacterial resistance

PREDISPOSING FACTORS

• Age

• Immune status

• Underlying diseases

• Contact with infectious persons

• Diagnostic and therapeutic interventions

• Duration of hospital stay

• Contaminated environmental sites

• Drug resistance of the endemic organisms

• Malnutrition

MODE OF TRANSMISSION

• FIVE MAIN ROUTES

a) INFECTION ACQUIRED THROUGH

CONTACT

Direct contact: through animate sources

i.e. from patient to patient on the hands of the

health care workers (hand borne route)

Indirect contact: through fomites

b) AIRBORNE TRANSMISSION

• Effectiveness of spread by this route depends on

The source

Degree of dispersal

Survival and retention of pathogenicity by the

microbe

Size of the infecting dose

General susceptibility of the patient

Eg: Measles, tuberculosis, chicken pox

c) DROPLET TRANSMISSION

• Large particle aerosols (>5µm in diameter)

• They do not remain suspended in the air

• Cannot travel more than 3 feet

• Introduced into the air when an infected patient

talks, coughs, sneezes or during procedures like

suctioning, bronchoscopy

• Eg: Corynebacterium diphtheriae,

Haemophilus influenzae, Mycoplasma

pneumoniae

d) VECTOR-BORNE TRANSMISSION

• Occurs when micro organisms are transmitted by

vectors

Eg: Malaria (mosquitoes)

Rat bite fever (rat)

e) VEHICLE TRANSMISSION

• Transmitted through contaminated items such as

food, water, medications, devices and equipments

PATHOGENS OF NOSOCOMIAL INFECTIONS

• Pathogens may be divided into three

Conventional pathogens: cause disease in healthy

persons

Conditional pathogens: cause disease in persons with

lowered resistance to infection

Opportunistic pathogens: cause generalised disease in

patients who have a greatly diminished resistance to

infection

MOST COMMON NOSOCOMIAL PATHOGENS BACTERIA

• Gram positive bacteria:- Staphylococcus aureus

- Methicillin resistant S.aureus

- Clostridium difficile

- Vancomycin resistant

Enterococcus

• Gram negative bacteria:- Pseudomonas spp.

-Acinetobacter spp.

-Enterobacteriaceae

VIRUSES

- Hepatitis B & C viruses

-Respiratory syncytial virus

-Rotavirus

-Enterovirus

-Human Immunodeficiency Virus

Other viruses such as –

-Cytomegalovirus,

-Ebola virus

-Varicella zoster virus

PARASITES

- Giardia lamblia

- Cryptosporidium parvum

- Toxoplasma gondii

- Sarcoptes scabies

FUNGI

- Aspergillus spp.

- Candida albicans

- Cryptococcus neoformans

MAJOR TYPES OF NOSOCOMIAL INFECTIONS

1) URINARY TRACT INFECTION

• Common nosocomial infection (40-45%)

• Associated with the indwelling bladder catheter

• Can occasionally lead to bacteraemia and death

• Etiological agents

• Enter via the periurethral route

• They multiply in the urine itself or on the catheters

• Diagnosis

2) SURGICAL WOUND INFECTION

• Second most common nosocomial infection(20-30%)

• Occurs in the incision site, but some may involve deep

soft tissue or adjacent sites

• Risk factors

• Etiological agents

• Diagnosis

3) NOSOCOMIAL PNEUMONIA

• Accounts for up to 15-20% of nosocomial infections

• Due to the inapparant aspiration of upper airway

secretions into the lower respiratory tract

• Supine position and intubation predispose to the

aspiration

• Ventillator associated pneumonia is the most common

Early onset pneumonia or late onset pneumonia

• Etiological agents

• Diagnosis

4) NOSOCOMIAL BLOODSTREAM INFECTION• Accounts for up to 5%

• Case fatality rates are high

• Associated with intravenous therapy devices and are

preventable

• When intravenous cannula is inserted, it bypasses normal

defences of skin and provides a potential entry site

• Organisms may be introduced from the skin flora

• Risk factors

• Etiological agents

CONSEQUENCES OF NOSOCOMIAL INFECTIONS

1. Serious illness/death

2. Prolonged hospital stay

3. Need for additional antimicrobial therapy

4. The infected patient becomes a source of infection

PREVENTION OF NOSOCOMIAL INFECTION

A. VACCINATION

• Hepatitis A and B vaccine

• Influenza vaccine yearly

• Measles vaccine

• Rubella vaccine

• DPT vaccine

B. UNIVERSAL PRECAUTIONS

Cardinal rules of universal precautions are as follows:

• Consider all patients potentially infectious

• Assume all blood and body fluids and tissues are

contaminated with a blood borne pathogen

• Assume all unsterile needles and sharps are similarly

contaminated

1. HANDWASHING

2.PERSONAL PROTECTIVE EQUIPMENT

• Gloves

• Masks

• Face/eye protection

• Gown

• Proper disposal of needles and sharps

• Central sterile supply department (CSSD)

3. PATIENT PLACEMENT

• Significant component of patient isolation precautions

• Patients, with highly transmissible diseases (eg:

chicken pox) or epidemiologically important (MRSA)

microorganisms, is placed in a single room

• Patients infected with the same microorganism usually

can share a room

• 2 types of isolation precautionsStandard precautionsTransmission based precautions

TRANSMISSION BASED PRECAUTIONS

• Private room

• Door may be left open but in case of airborne

transmission, the door should be kept closed and

with a negative air pressure

• Wear mask if within 1 meter (3 feet) of patient in

case of droplet and airborne transmission

• Limit transport of patient to essential purposes only

• During transport, patient must wear surgical mask

4. WASTE DISPOSAL

• Colour coded bags are used

Red bags: non-pathogenic material

Yellow bags:contaminated or soiled

materials other than sharps

Black bags: non-contaminated articles only

Blue bags: solid wastes and sharps

LEVEL OF DISINFECTION

PATIENT EQUIPMENTS

•Sterilization or High

level disinfection

•Intermediate level

•Low level disinfection

surgical

instrumentations Ex:

arthroscopes, endoscopes

gastroscopes

bedpans, blood

pressure cuffs, and

bedside tables ,

5. DISINFECTION OF THE EQUIPMENTS

6. SPILL CLEAN UP

• Dakin’s solution or sodium hypochlorite solution

• Wash the area with detergent and water

7. POST EXPOSURE PROPHYLAXIS

• Human immunodeficiency virus - antiretroviral drugs

• Hepatitis B virus - Hepatitis B immune globulin

• Neisseria meningitidis - Rifampin, Ciprofloxacin or

ceftriaxone

INFECTION PREVENTION

UTI

Surgical wound

infection

•Limit duration of catheter•Aseptic technique at insertion•Maintain closed drainage

•Meticulous technique is required•Avoid long pre-operative hospital stay•Control the underlying diseases•Aseptic practice in operating room•Surgical wound surveillance

PREVENTION OF COMMON ENDEMIC NOSOCOMIAL INFECTION

Nosocomial

pneumonia

•Ventillator associated

•Aseptic intubation and suction

•Limit duration

•Non-invasive ventillation

Others

•Influenza vaccination for staff

•Isolation policy

•Sterile water for oxygen and

aerosol therapy

Vascular device

infection•Closed system

•Limit duration

•Aseptic technique at insertion

INFECTION CONTROL PROGRAMME

• Includes various programmes

National or regional programmes

To monitor selected infections

Set relevent national objectives with other national

health care facilities

Hospital programmes

Includes the infection control committee

INFECTION CONTROL COMMITTEE (ICC)

• Hospital epidemiologist (infectious disease physician)

• Infection control practitioner (nurse)

• Microbiologist

• Pharmacist

• Personnel representing various support services like

house-keeping and central services

ROLE OF ICC

• Surveillance of nosocomial infections

• Establishment and monitoring antibiotic policies

• Investigation of outbreaks

• Education regarding nosocomial infection control

SURVEILLANCE

• Definition

• Objectives of surveillance program

To establish a system to evaluate the incidence and factors

influencing

Identify hospital practices to reduce nosocomial infections

To meet national and local accreditation standards

To use an epidemiologic approach to evaluate infections

• SOURCE OF SURVEILLANCE DATA

Ward rounds

Microbiology laboratory reports

Other diagnostic test reports

Discussion of cases with the clinical staff

ACTIVE SURVEILLANCE

Prevalence study

• Infections in all patients hospitalized at a given point in

time are identified in the entire hospitals, or on selected

units

• Prevalence rate

No: of infected patients at the time of study / No: of

patients observed at the same time * 100

Ex: prevalence (%) of UTI for 100 patients with a urinary

catheter

Incidence rate

• No: of new nosocomial infections acquired in a period /

total of patient days for the same period * 1000

• Ex: incidence of bloodstream infection for 1000 patient

days

• Incidence of VAP for 1000 patient days

Attack rate

• No: of new infections acquired in a period/ No: of

patients observed in the same period * 100

• Ex: attack rate of UTI for 100 hospitalized patients

ROLE OF MICROBIOLOGY LABORATORY

• Detects potential pathogens

• Identifies them to species level

• Performs susceptibility testing

• Monitors multidrug resistant organisms

• Performs typing of strains to establish

relatedness between isolates of the same

species

Levels of bacteria in air are evaluated by air

sampling methods such as

• Sedimentation (settle plate technique)

• Impaction (Bourdillon’s slit sampler method)

• Impingement

• Filtration

• Precipitation

OUTBREAK INVESTIGATION

• Definition

• The process includes

Contact the laboratory to save all the isolates

Case definition to be decided

epidemic curve to be plotted based on time and number of

cases

Infection control measures to be instituted

Cultures of possible source to be analyzed

Molecular typing to be done

Surveillance to be maintained

Report to be submitted to ICC

ICC to revise and review policies and formulate

antibiotic policy

EPIDEMIOLOGICAL TYPING

• 2 Major ways to type strains

Phenotypic method

Molecular typing method

PHENOTYPIC METHOD

Biotyping

Antibiograms

Serotyping

Bacteriocin typing

Bacteriophage typing

MOLECULAR METHODS

Plasmid analysis

Restriction endonuclease analysis of chromosomal DNA

Pulsed field gel electrophoresis

Polymerase chain reaction

ANTIBIOTIC POLICY

CONCLUSION

Nosocomial infections remain an important cause of

morbidity and mortality in hospitals even now.

Approximately one third of nosocomial infections are

preventable. The infection control can be very cost-

effective. Surveillance is important to establish baseline

data and to recognize the need to investigate potential

outbreaks.

The major advances in overall control of infectious

diseases have resulted from immunization and improved

hygiene, particularly hand washing.

“The very first requirement in a hospital is that it should do the sick no harm”

REFERENCES

• Clinical and pathogenic microbiology; Barbara J

Howard; 2nd edition

• Prevention Of Hospital Acquired Infections; World

Health Organization; 2nd edition

• Harrison’s Principles of internal medicine; Volume 1;

17th edition

• Topley and Wilson’s Microbiology and Microbial

infections; Bacteriology volume 1; 10th edition

• Bailey and Scott; Diagnostic microbiology; 11th edition

Thank you