HOSPITAL ACQUIRED
INFECTION ( HAI)
BY,
MS. MILAN SAWANT,
M.SC. NURSING

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,
and
➜ the symptoms should appear at least after 48 hours of
admission.

HOSPITAL ACQUIRED INFECTION(HAI)
➜This also include:
➜ Infections that are acquired in the hospital but symptoms appear after
discharge
➜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).

BURDEN OF HAI
➜HAIs are one of the most common adverse events in the health care delivery
system.
 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.

Factors Affecting HAI
➜ Immune status
➜ Hospital environment
➜ Hospital organisms
➜ Diagnostic or therapeutic interventions
➜ Poor hospital administration

Sources of Infection
 Endogenous Source
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.

CONT…
 Exogenous Source :
are from the hospital environment, healthcare workers (HCW), or patients.
Environmental sources
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
 Healthcare workers
May be potential carriers, harboring many organisms; which may be multidrug-
resistant, e.g.nasal carriers of Methicillin-resistant Staphylococcus aureus (MRSA)
Other Patients
Other patients of the hospital may also be the source of infection.

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
important.

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.

The ESKAPE pathogens:
❑ Enterococcus faecium
❑Staphylococcus
 aureus
❑Klebsiella pneumoniae
❑Acinetobacter
 baumannii
❑Pseudomonas
 aeruginosa
❑Other infections
❑ Escherichia coli
❑SARS-CoV-2 (COVID-19)
❑Nosocomially-acquired
Mycobacterium tuberculosis
❑Legionella
 pneumophila
❑Candida albicans
❑Clostridium difficile diarrhea

Modes of Transmission
 Microorganisms spread in the hospital through several modes
such as contact, droplet and airborne transmissions.

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%).

Catheter-associated Urinary Tract Infection
(CAUTI)
 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.
 Definition :
Catheter-associated bacteriuria (CA-bacteriuria) has been defined as
presence of significant bacteriuria in a catheterized patient.

Catheter-associated Urinary Tract Infection
(CAUTI)
 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

MICROBIOLOGY
 A broad range of bacteria can cause CAUTI, most of which are
multidrug resistant.
 In short-term catheterized patients: Most CAUTI are caused by
the monomicrobial pathogens such as gram negative bacilli or
enterococci.
 E. coli is the predominant agent, although it is not as prevalent as
in community-associated UTI

MICROBIOLOGY
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.

CENTRAL LINE ASSOCIATED BLOODSTREAM
INFECTION (CRBSI)
 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
surveillance purpose.

CENTRAL LINE ASSOCIATED BLOODSTREAM
INFECTION (CRBSI)
 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)

Cont.
 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-
tunneled).

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.

Microbiology
 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).

Microbiology
 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

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
left untreated
□ 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.

Microbiology
 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
(CoNS)
- 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

Microbiology
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.

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
DAIs.
□ 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