2. HOSPITAL ACQUIRED INFECTION(HAI)
➜Hospital acquired infection can be deﬁned as—
➜ the infections acquired in the hospital by a patient admitted for a reason
other than the infection in context,
➜ the infection should not be present or incubating at the time of admission,
➜ the symptoms should appear at least after 48 hours of
3. HOSPITAL ACQUIRED INFECTION(HAI)
➜This also include:
➜ Infections that are acquired in the hospital but symptoms appear after
➜Occupational infections among staff of the healthcare facility (e.g. needle
stick injury transmitted infections)
➜Infection in a neonate that results while passage through the birth canal (in
contrast to congenital infections due to transplacental transmission, which
are not HAI).
4. BURDEN OF HAI
➜HAIs are one of the most common adverse events in the health care delivery
According to World Health Organization (WHO), on average at any given
time 7% of patients in developed and 10% in developing countries acquire
at least one HAI.
Mortality from HAI occurs in about 10% of affected patients. Treatment of
these HAIs adds a huge economic burden to the hospital.
5. Factors Affecting HAI
➜ Immune status
➜ Hospital environment
➜ Hospital organisms
➜ Diagnostic or therapeutic interventions
➜ Poor hospital administration
6. Sources of Infection
The majority of nosocomial infections are endogenous
in origin, i.e. they involve patient’s own microbial ﬂora which may invade the
patient’s body during some surgical or instrumental manipulations.
Exogenous Source :
are from the hospital environment, healthcare workers (HCW), or patients.
Include inanimate objects, air, water and food in the hospital. Inanimate
objects in the hospital are medical equipment (endoscopes, catheters, etc.), bedpans, surfaces
contaminated by patients’ excretions, blood and body ﬂuids
May be potential carriers, harboring many organisms; which may be multidrug-
resistant, e.g.nasal carriers of Methicillin-resistant Staphylococcus aureus (MRSA)
Other patients of the hospital may also be the source of infection.
8. MICRO-ORGANISMS IMPLICATED IN HAIS
HAIs can be caused by almost any microorganism, but those which
survive in the hospital environment for long periods and develop
resistance to antimicrobials and disinfectants are particularly
9. The ESKAPE pathogens:
They are responsible fora substantial percentage of nosocomial infections in the
modern era and represent the vast majority of multidrug resistant isolates present
in a hospital.
11. Modes of Transmission
Microorganisms spread in the hospital through several modes
such as contact, droplet and airborne transmissions.
12. Major Healthcare-associated Infection Types
Though several types of HAIs exist, there are four most common types (listed below)
which are often monitored to estimate the burden of HAI in a hospital. Out of these, the ﬁrst
three are together called as device associated infections (DAIs).
1. Catheter-associated urinary tract infection (CAUTI, 33%)
2. Central line-associated blood stream infection (CLABSI, 13%)
3. Ventilator-associated pneumonia (VAP, 15%)
4. Surgical site infection (SSI, 31%).
13. Catheter-associated Urinary Tract Infection
CAUTI is considered as the most common HAI worldwide, accounting for up
to 40% of nosocomial infections. About 70–80% of healthcare–associated UTI
are attributable to the presence of an indwelling urinary catheter.
Catheter-associated bacteriuria (CA-bacteriuria) has been deﬁned as
presence of signiﬁcant bacteriuria in a catheterized patient.
14. Catheter-associated Urinary Tract Infection
It can be classiﬁed as:
□ Catheter-associated UTI (CAUTI): Catheter Associated-bacteriuria
with symptoms or signs referable to the urinary tract
□ Catheter-associated asymptomatic bacteriuria (CA-ASB):
Catheter Associated-bacteriuria without symptoms or signs
referable to the urinary tract
A broad range of bacteria can cause CAUTI, most of which are
In short-term catheterized patients: Most CAUTI are caused by
the monomicrobial pathogens such as gram negative bacilli or
E. coli is the predominant agent, although it is not as prevalent as
in community-associated UTI
Other gram-negative bacilli such as Klebsiella, Pseudomonas and
Acinetobacter and gram-positive cocci such as Enterococcus
account for most of the other infections.
In long-term catheterized patients, CAUTI is usually
polymicrobial. In addition to the pathogens of short term
catheterization, other organisms such as Proteus, Providencia and
Morganella are also encountered.
18. CENTRAL LINE ASSOCIATED BLOODSTREAM
It refers to the development of bloodstream infections (BSI) in
hospitalized patients which is attributed to the presence of a central
line as a source of infection and is not associated with any other
secondary cause of BSI.
There is another related terminology called CLABSI (central line-
associated bloodstream infection), which is strictly used only for
19. CENTRAL LINE ASSOCIATED BLOODSTREAM
Central Line or Central Venous Catheter
A central line (CL) is an intravascular
device that terminates in the great vessels. It is needed for various
purposes such as central venous pressure monitoring and
administration of drugs, total parenteral nutrition, etc. and for
hemodialysis access (hemodialysis catheters)
Central line can be classiﬁed in various ways depending up on:
□ Its intended life span, e.g. temporary or short-term (<72 hrs)
versus permanent or long-term (≥72 hrs)
□ Its site of insertion (e.g. subclavian, femoral, internal jugular
and peripheral veins)
□ Its pathway from skin to great vessel (e.g. tunneled versus non-
22. VENTILATOR -ASSOCIATED PNEUMONIA
Ventilator-associated pneumonia (VAP) is the second most common nosocomial infection
(after CAUTI) and accounts for 15–20% of the total HAIs.
□ It is the most common cause of death among HAIs, with a mortality rate of up to 40%
and is the primary cause of death in ICUs
□ The VAP rate varies from 1.0 to 46.0 per 1000 mechanical ventilation (MV) days,
depending up on the ICU facility and the hospital.
VAP can be divided into early- and late-onset.
□ Early-onset VAP: It occurs during the ﬁrst 4 days of mechanical ventilation. It is
caused by typical community organisms such as pneumococcus, H. inﬂuenzae, methicillin
susceptible S. aureus (MSSA), etc.
□ Late-onset VAP: It develops ≥5 days after mechanical ventilation and is commonly
caused by typical multidrug resistant hospital pathogens—P. aeruginosa, Acinetobacter
baumannii, E.coli, Klebsiella and methicillin resistant S. aureus (MRSA).
It is associated with high attributable mortality.
Here, the source of infection may be:
□ Endogenous, i.e. patient’s own oropharyngeal microbial ﬂora
transmitted to lungs by aspiration
□ Exogenous, e.g. hospital environmental sources like air, water, reusable
equipment, nebulized medication, etc. contaminated with environmental
26. Surgical site infections (SSI)
Surgical site infections are deﬁned as infections that develop at the surgical
site within 30 days of surgery (or within 90 days for some surgeries such as breast, cardiac
and joint surgeries including implants).
□ SSIs can cause signiﬁcant morbidity and mortality as well as economic burden if
□ SSI affects up to one third of patients who have undergone a surgical procedure,
incidence is higher following abdominal operations
□ In India, several studies reported SSI rate ranging from 4 to 11 per 100 surgeries.
The type of etiological agents implicated in SSI depends upon the site of surgical procedure
and the source of infection from which they are acquired.
□ Endogenous source such as the patient’s own ﬂora present on
- Skin: S. aureus (the most common organism causing SSI), coagulase negative staphylococci
- Mucosa (from opened viscus such as GIT, respiratory or genitourinary): Consists of
predominantly aerobic gram-negative bacilli (E.coli, Klebsiella), grampositive cocci
(Enterococcus) and anaerobes such
Bacteroides, and others
Exogenous source from contact with the operative room personnel or instruments or
environment: S. aureus and gram-negative bacilli including nonfermenters such as
Pseudomonas and Acinetobacter.
The inoculum load and the virulence of the microorganism can determine the risk of SSI
□ Inoculum of bacteria: Surgical procedures involving the sites (e.g. bowel, vagina)
which are heavily colonized with bacteria have a higher risk of developing SSI as large
inoculum of bacteria lodge into the wound during surgery
□ Virulence of bacteria: Higher is the virulence of infecting organism, more is the risk of
development of SSI.
32. Prevention of Device-associated Infections
The majority of device-associated infections (DAIs) encountered in hospital
are CAUTI, CLABSI and VAP.
Care Bundle Approach
Healthcare facilities must adhere to care bundle approach for the prevention of
□ Care bundle comprises of 3 to 5 evidence-based elements with strong clinician
agreement; each of the component must be followed during the insertion or
maintenance of the device
□ Compliance to the care bundle is calculated as all or-none way, i.e. failure of compliance to
any of the component leads to non-compliance to the whole bundle