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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