Infections in ICUs

Dr Rajesh Karyakarte MD
Dean,
Government Medical College,
Akola
INFECTIONS IN SICU AND ICU

WHAT IS AN ICU?
• An intensive care unit (ICU) is defined as a
specially staffed, specialty equipped,
separate section of a hospital dedicated to
the observation, care, and treatment of
patients with life threatening illnesses,
injuries, or complications from which
recovery is possible

HISTORY
• ICU care dates back to the polio epidemic
in 1950s
• The technique of controlled ventilation
was then extended to patients with drug
overdose, tetanus, and chest trauma, with
resultant improvement in survival
Yeolekar ME, Mehta S. ICU Care in India - Status and Challenges. Indian Journal of Basic and Applied Medical Research 2014: 3, Issue- 4, 46-63.

TYPES OF ICUs
• Medical,
• Surgical,
• Cardiac,
• Neurology,
• Paediatric and
• Neonatal

INFECTIONS IN ICUs
• Patients in intensive care units (ICUs) have
a higher risk of acquiring hospital-
associated infections than those in non-
critical care areas
• Up to 45% of hospital-acquired infections
occur in ICU patients, although these
patients occupy only 8% of hospital beds
Donowitz LG, Wenzel RP, Hoyt JW. High risk of hospital-acquired infection in the ICU patient. Crit Care Med 1982; 10:355-357

INFECTIONS IN ICUs
• ICU-acquired infection rates are five to ten
times higher than hospital-acquired
infection rates in general ward patients
• The ICUs are an area of considerable
antibiotic use in which antibiotic-resistant
organisms are prevalent
Weinstein RA. Nosocomial infection update. Emerg Infect Dis 1998;4:416-420
Albrich WC, Angstwurm M, Bader L, Gartner R. Drug resistance in intensive care units. Infection 1999;27(suppl 2): S19-23

INFECTIONS IN ICUs
• ICU patients with infections can be divided
into three groups, those with:
• Community-acquired infections,
• Hospital-acquired infections before
transfer to the ICU,
• ICU-acquired infections

INFECTIONS IN ICUs
• ICU patients with a stay of more
than 24 hours, have 18.9%
probability of developing
infection during their ICU stays
Alberti C, Brun-Buisson C, Burchardi H, et al. Epidemiology of sepsis and infection in ICU patients from an international multicentre cohort study. Intensive
Care Med 2002; 28:108-121

SITES OF INFECTION
• The most common sites of infection are
• Lungs (pneumonia, 46.9%);
• Other respiratory tract (17.8%);
• Urinary tract (17.6%);
• Bloodstream (12%);
Vincent JL, Bihari DJ, Suter PM, et al. The prevalence of nosocomial infection in intensive care units in Europe. Results of the European Prevalence of
Infection in Intensive Care (EPIC) Study. EPIC International Advisory Committee. JAMA 1995;274:639-644

SITES OF INFECTION
• Other common sites of infection are
• Wound (6.9%);
• Ear, nose, and throat (5.1%);
• Skin and soft tissue (4.8%);

SITES OF INFECTION
• Other common sites of infection are
• Gastrointestinal tract (4.5%);
• Cardiovascular system, including
phlebitis (2.9%); and
• Clinical sepsis (2%)

• Major sites of infection in medical
and surgical patients in
medical/surgical intensive care
units (U.S. National Nosocomial
Infections Surveillance 1992-1998)
• BSI, bloodstream
infection
• UTI, urinary tract
infection
• PNE, pneumonia
SITES OF INFECTION
Semin Respir Crit Care Med. 2003;24(1) © 2003 Thieme Medical Publishers

PATHOGENS IN ICU-ACQUIRED INFECTIONS
Richards MJ, Edwards JR, Culver DH, Gaynes RP. Nosocomial infections in combined medical-surgical intensive care units in the United
States. Infect Control Hosp Epidemiol 2000;21:510-515

PATHOGENS IN ICU-ACQUIRED INFECTIONS
9. Richards MJ, Edwards JR, Culver DH, Gaynes RP. Nosocomial infections in combined medical-surgical intensive care units in the United

ANTIMICROBIAL RESISTANCE OF ICU
PATHOGENS
• Antimicrobial-resistant pathogens
frequently cause ICU-acquired infection,
and
• Their prevalence can vary enormously
depending on geographic location as well
as location among ICU types
Fridkin SK, Gaynes RP. Antimicrobial resistance in intensive care units. Clin Chest Med 1999;20:303-316, viii

RATES AND PREVALENCE OF ICU-
ACQUIRED INFECTIONS
• The EPIC study in 1992 reported a
prevalence of ICU infections of 20.6%
• An incidence density of 23.7 episodes per
1000 patient-days was reported from 119
U.S. ICUs from surveillance data between
1986 and 1990
Vincent JL, Bihari DJ, Suter PM, et al. The prevalence of nosocomial infection in intensive care units in Europe. Results of the European
Prevalence of Infection in Intensive Care (EPIC) Study. EPIC International Advisory Committee. JAMA 1995;274:639-644
Jarvis WR, Edwards JR, Culver DH, et al. Nosocomial infection rates in adult and pediatric intensive care units in the United States. National
Nosocomial Infections Surveillance System. Am J Med 1991;91(3B):185S-191S

RATES AND PREVALENCE OF ICU-
ACQUIRED INFECTIONS
• The most significant risk factor for most
ICU-acquired infections is the use of
• Invasive devices, including
• Mechanical ventilation,
• Central venous catheters, and
• Urinary catheters
9. Richards MJ, Edwards JR, Culver DH, Gaynes RP. Nosocomial infections in combined medical-surgical intensive care units in the United

DEVICE-UTILIZATION RATIOS BY ICU TYPE
• There are considerable differences in rates
of device use between different types of
ICU and within a given ICU type
• Device-utilization is significantly higher in
major teaching hospitals as compared with
other hospitals for all three major devices
Richards MJ, Edwards JR, Culver DH, Gaynes RP. Nosocomial infections in medical intensive care units in the United States. National
Nosocomial Infections Surveillance System. Crit Care Med 1999;27:887-892

DEVICE-UTILIZATION RATIOS BY ICU TYPE
*Urinary catheter utilization = (number of urinary catheter-days)/(number of patient-days). **Central venous line utilization = (number of central line-days)
/(number of patient-days). ***Ventilator utilization = (number of ventilator-days)/(number of patient-days).
U.S. National Nosocomial Infections Surveillance 1995-2001

COMPARING INTENSIVE CARE UNIT TYPES
• The types of infection and the
pathogens vary between different
ICU types

MEDICAL-SURGICAL INTENSIVE CARE
UNITS
• Combined medical-surgical ICUs (MSICUs)
is defined as an ICU where neither medical
nor surgical patients represent more than
80% of total patients in the unit

SURGICAL INTENSIVE CARE UNITS
• Nosocomial pneumonias constitute 43% of
hospital-acquired infections in SICUs
• VAP rates in general SICUs are higher than
cardiothoracic ICUs but lower than
neurosurgical, burn, and trauma ICUs
• The second most common infection in
SICUs is UTI (25%)

SURGICAL INTENSIVE CARE UNITS
• Bacteriology of SICUs have changed over
time
• Enterobacter sp and Acinetobacter in
VAP, and Candida in UTIs
• Gram-negative bacilli and Enterococcus
have replaced S. aureus as the most
common isolates responsible for surgical
site infections

PEDIATRIC INTENSIVE CARE UNITS
• BSI is the most common
• Urinary catheter use is markedly lower
than in adult ICUs, and
• Gram-negative bacteria were more
frequently reported as causing primary
BSIs than in adults, and Enterobacter sp is
most common

PEDIATRIC INTENSIVE CARE UNITS
• Viral infections are significant more
common
• The problems of antibiotic resistance,
particularly, vancomycin-resistant
enterococci (VRE), is less than in adult
ICUs

NEONATAL ICU (NICU)
• NICU patient infection rates are reported
to range from 6 to 25%
• Infants with birth weights < 1500 g have
significantly higher rates of infection

NICU
• Primary BSIs are the most frequent
hospital-acquired infection in all birth
weight groups
• All aspects of immune function are
immature in a neonate admitted in NICU

NICU
• Fungal infections in neonates, in particular
C. albicans and C. parapsilosis, have
increased
• Risk factors include broad-spectrum
antibiotic use, intravenous fat emulsions,
and use of central lines

NICU
• Catheter colonization rates are
significantly greater than those reported in
adults
• Gram-positive cocci are the most common
nosocomial pathogens in the neonate

NICU
• Group B streptococci were associated with
46% of maternally acquired BSIs and
• CONS, with 58% of non-maternally
acquired BSIs in NNIS surveillance
between 1986 and 1994

TRAUMA INTENSIVE CARE UNITS
• About 40% of patients with traumatic
injuries are admitted to the ICU
• Sepsis is a major cause of mortality in
these patients
• Device-utilization rates are among the
highest compared with other ICU types

• In one cohort of 10,557 patients, the
nosocomial infection rate was 20%
• ICU-acquired infection was four times
more common in blunt versus penetrating
injury

• The most common infections are
respiratory infection, followed by UTI
• Surgical wound infections and skin/soft
tissue infections accounted for 18% and
13% of infections, respectively

• Trauma patients are significantly more
likely to develop pneumococcal or
Haemophilus influenzae pneumonia than
patients from other ICUs

• S. aureus has consistently proven to be the
most frequently isolated pathogen in the
trauma population
• Head-injured patients colonized with S.
aureus are at high risk for S. aureus
pneumonia

BURN INTENSIVE CARE UNITS
• Overall, Burn ICU-acquired infection rates
are the highest reported despite lower
device-utilization rate compared with
other ICU types

• These patients are at high risk due to factors
such as
• Burn-related immune suppression,
• Loss of skin and mucous membrane barriers,
• Inhalation injury,
• Prolonged hospitalization, and
• Broad-spectrum antibiotic use

• In a Swedish study, the most common
infection was
• Burn wound infection (60%), followed
by
• BSI (20%), UTI (10%), and
• Pneumonia (10%)

• Prolonged length of stay correlated with
burn wound colonization by
• Enterobacteriaceae, P aeruginosa, and S
aureus in one study
• P aeruginosa was the most frequently
isolated pathogen in several studies

• In a study of burn patients that were
mechanically ventilated
• Patients became colonized by the
second week with Acinetobacter, which
became the most common organism
isolated in VAP, BSI, and wound swab
cultures

MEDICAL INTENSIVE CARE UNITS
• NNIS surveillance data from 112 medical
ICUs from 1992 to 1997 reported that
• UTIs were the most common type of
infection (31%) followed by
• Pneumonia (27%) and
• BSIs (19%)

• The infection rate is 19.9 per 1000 patient-
days
• Gram-positive pathogens account for 65%
of BSIs
• Enterococci were more frequently
reported than S. aureus as pathogens in
primary BSIs

• Fungi constituted 40% of urinary isolates
• Enterococcus was as common a urinary
pathogen as E. coli
• Third-generation cephalosporin and
vancomycin use was considerably higher in
MICUs than in MSICUs

INTENSIVE CORONARY CARE UNITS
• Intensive coronary care unit (CCU) patients
differ in risk of nosocomial infection
compared with other ICU patients
• They are frequently admitted directly to
the unit without prior antibiotic use or
exposure to other hospital pathogens

INTENSIVE CORONARY CARE UNITS
• Device-utilization rates are the lowest
among the different adult ICU types
• The urinary tract is the most frequent site
of infection
• NNIS surveillance data from 93 CCUs
(1992-1997) reported an overall infection
rate of 10.6/1000 patient-days

OUTBREAKS IN ICUs
• Outbreaks are common in the ICU
• Nosocomial outbreaks occur at a
frequency of 1 in 10,000 to 12,000 hospital
discharges

OUTBREAKS IN ICUs
• Over half are caused by gram-negative
organisms, although S. aureus is the single most
common cause
• However the majority of isolates reported were
multi-resistant gram-negative bacilli, most
frequently Acinetobacter, Enterobacter sp,
and P. aeruginosa

OUTBREAKS IN ICUs
• Over half of the published outbreaks were
in NICUs
• This may also reflect the particular
susceptibility of low birth weight and
premature infants to sepsis

OUTBREAKS IN ICUs
• Outbreaks may be of either exogenous or
endogenous origin
• Exogenous infections usually have a
common inanimate or animate source,
whereas
• Endogenous infections are transmitted
from the patient with the outbreak
strain

OUTBREAKS IN ICUs
• The epidemiology of resistant organisms is
characterized by multiple monoclonal
outbreaks, followed by endemic
colonization in the ICU
• Indirect transmission from patient to
patient on the hands of health care
workers becomes the most important
mode of transmission

OUTBREAKS IN ICUs
• In fact, the majority of recent outbreaks
identified problems with infection control
measures such as handwashing practices
and environmental disinfection
• The molecular methods have a
fundamental role in understanding the
epidemiology of outbreaks in ICUs

RISK FACTORS FOR ICU-ACQUIRED
INFECTIONS
• The most significant risk factor for
nosocomial pneumonia in ICU patients is
endotracheal intubation with mechanical
ventilation, which increases the risk of
pneumonia by 6 to 21 times

INFECTIONS
• Regarding other sites of infection, central
catheters account for 97% of all
nosocomial BSIs. Scheduled replacement
of catheters has not been shown to
prevent infection

INFECTIONS
• Duration of urinary catheterization is the
most important risk factor for acquisition
of nosocomial UTIs
• Of uninfected patents, 2 to 16% will
acquire a UTI for each day of
catheterization

INFECTIONS
• Naso-tracheal intubation is the most
significant risk factor for acquisition of
nosocomial sinusitis
• Congestion of nasal blood vessels due to
positive pressures used in mechanical
ventilation, and the absence of
gravitational forces in the supine position
may impair sinus drainage

MORTALITY FROM ICU-ACQUIRED
INFECTIONS
• Many international studies have reported
high rates of crude mortality from ICU-
acquired infections, reflecting both
• the severity of the underlying illnesses
in patients acquiring these infections,
and
• any attributable mortality from the ICU-
acquired infection

INFECTIONS
Pneumonia
• Crude mortality rates for nosocomial
pneumonia in the ICU have been reported
as approximately 50%
• It has been generally accepted that VAP
has significant attributable mortality

INFECTIONS
Pneumonia
• High-risk pathogens (P. aeruginosa,
Acinetobacter, and Stenotrophomonas
maltophilia) may also be independent risk
factors for mortality

INFECTIONS
Bloodstream Infections
• Carefully designed, large, and recent
studies report substantial crude and
attributable mortality from these
infections

IMPACT OF SPECIFIC PATHOGENS AND
ANTIBIOTIC RESISTANCE
• In a large point prevalence study
• Mortality was three times higher in
patients with methicillin-resistant S.
aureus (MRSA) as compared with
methicillin-sensitive S. aureus with
lower respiratory tract infections
Ibelings MM, Bruining HA. Methicillin-resistant Staphylococcus aureus: acquisition and risk of death in patients in the intensive care unit. Eur J Surg
1998;164:411-418

• Vancomycin resistance (as compared with
vancomycin sensitivity) of enterococcal
bacteremia was associated with prolonged
hospital stay but not increased mortality
in an MSICU
Mainous MR, Lipsett PA, O'Brien M. Enterococcal bacteremia in the surgical intensive care unit: does vancomycin resistance affect mortality?
The Johns Hopkins SICU Study Group. Arch Surg 1997;132:76-81

• In patients with antibiotic-susceptible
gram-negative bacteremias and antibiotic-
resistant gram-negative bacteremias, there
was no difference in mortality

• P. aeruginosa, Acinetobacter
baumannii infection,
and Candida infections have been
reported to have significant attributable
mortality

COSTS OF ICU-ACQUIRED INFECTIONS
• Several reports identify attributable costs to
ICU-acquired BSIs and pneumonia,
• Warren et al noted longer hospital and ICU stays
in survivors of primary BSIs
Warren DK, Zack JE, Elward AM, Cox MJ, Fraser VJ. Nosocomial primary bloodstream infections in intensive care unit patients in a nonteaching
community medical center: a 21-month prospective study. Clin Infect Dis 2001;33:1329- 1335

• Intubated trauma patients with
pneumonia required prolonged care, and
hospital costs were 1.5 times higher
• Infections with MRSA and VRE lead to
increased length of stay and cost of care in
comparison to infections with sensitive
isolates

• Additional nursing workload in managing
ICU patients with multi-resistant bacteria
may increase costs

NURSING AND MEDICAL STAFFING AND
INFECTION RATES
• Several reports have indicated that nurse
understaffing or nursing staff experience
may affect ICU-acquired infection rates

INFECTION RATES
• Patient acquisition of MRSA in an English
ICU was found to correlate with peaks of
nursing workload and reduced
nurse:patient ratios
Vicca AF. Nursing staff workload as a determinant of methicillin-resistant Staphylococcus aureus spread in an adult intensive therapy unit. J
Hosp Infect 1999;43:109-113

INFECTION RATES
• Physicians-in-training has been shown to
increase the use of maximal barrier
precautions during central line insertion
and to reduce the risk for central line-
associated BSIs
Sherertz RJ, Ely EW, Westbrook DM, et al. Education of physicians-in-training can decrease the risk for vascular catheter infection. Ann
Intern Med 2000;132:641-648

ANTIBIOTIC USE IN INTENSIVE CARE
UNITS
• Antimicrobial use and antimicrobial
resistance is higher in ICUs and varies
enormously between hospitals
• Antimicrobial resistance in the ICU impact
mortality as it affects appropriateness of
empiric therapy

UNITS
• In a study of 2000 ICU patients
• inadequate antimicrobial treatment of
ICU nosocomial infections occurred in
8.5% of patients and was associated
with substantial mortality (52.1%)
• It was most important factor affecting
hospital mortality
Dupont H, Mentec H, Sollet JP, Bleichner G. Impact of appropriateness of initial antibiotic therapy on the outcome of ventilator-
associated pneumonia. Intensive Care Med 2001; 27:355-362

UNITS
• In another study, inappropriate initial
antibiotic treatment of VAP in the first 48
hours increased ICU length of stay (12 days
vs 24 days)
• It increased crude hospital mortality
despite equal severity of illness at the
time of diagnosis of VAP
Dupont H, Mentec H, Sollet JP, Bleichner G. Impact of appropriateness of initial antibiotic therapy on the outcome of ventilator-associated
pneumonia. Intensive Care Med 2001; 27:355-362

SURVEILLANCE OF ICU-ACQUIRED
INFECTIONS
• SENIC study (1985) showed that
surveillance is the key element of effective
infection control programs
• SENIC = Study of the Efficacy of
Nosocomial Infection Control
Haley RW, Morgan WM, Culver DH, et al. Update from the SENIC project: hospital infection control: recent progress and opportunities under
prospective payment. Am J Infect Control 1985;13:97-108

INFECTIONS
• Monitoring of infection or colonization
of patients with antimicrobial-resistant
organisms
• Selective screening for MRSA nasal
carriage and interventions caused a
reduction of MRSA incidence in the ICU
from 5.8 to 2.6%

INFECTIONS
• Molecular typing of organisms helps
in epidemiology of hospital-acquired
infections
• It is now fundamental tool in
understanding transmission of ICU
pathogens

INFECTIONS
• Molecular typing helps in
differentiating a series of sporadic
infections against outbreaks with a
single clone

Infections in ICUs

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