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Nosocomial Infections
J.B. Handler, M.D.
Physician Assistant Program
University of New England
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Abbreviations
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NCI- nosocomial infection
IV- intravenous
ICU- intensive care unit
CCU- coronary care unit
E coli- Escherichia coli
Abd- abdomen
C difficile- clostridium difficile
S aureas- Staph aureas
S epidermidis- Staph epidermidis
S pyogenes- Strep pyogenes
DC- discontinue
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Nosocomial Infections (NCI)
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Infections acquired in the hospital or
other in-patient health care facility, often
developing within 48-72 hours of
admission; NCI also common with
prolonged hospitalization (seriously ill).
Historical information:
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Florence Nightingale (19th century) studies of
mortality in military hospitals.
Infections carried by healthcare workers to
patients could be prevented by washing
hands between patient contacts (20th
century).
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Nosocomial Infections (NCI)
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Incidence: 5% of all hospitalized
patients in the U.S.; 2-4 million NCI
annually with significant morbidity
and 100,000 annual deaths.
Cost: Billions of excess health care
dollars.
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Sources of Infection
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Endogenous: skin, GI or respiratory tract;
often from organisms indigenous to those
areas.
Exogenous: transmitted to the patient
from external sources.
Modes of transmission: contact (Cdifficile, Shigella, S aureas, S epidermidis,
S pyogenes, viruses) droplet, airborne,
common vehicle transmission
(contaminated multi-med vial).
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Elevated Temperature
Infection: Etiology of 75% of
fevers.
 Drug fever
 Post-op fever (atelectasis)
 Pancreatitis
 MI
 Large hematoma
 Thromboembolic disease
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NCI: Key Issues
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Many infections are a direct result of
use of invasive devices for
monitoring/treatment: IV catheters,
central venous lines, Foley
catheters, surgical drains, dialysis
catheters and shunts, and oral or
nasotracheal tubes for ventilatory
support.
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NCI: Key Issues
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Patients are often seriously ill (ICU/CCU)
with prolonged hospitalization and may
have received one or more courses of
broad spectrum antibiotics. NCI are often
antibiotic resistant. This includes
Nafcillin, Cephalosporin and new
Vancomycin resistant strains
(enterococcus, emerging S aureas).
“Hospital ecology”: organisms previously
identified with antibiotic resistance; very
difficult to eradicate.
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NCI: Key Issues
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Antibiotic use must be limited to the
treatment of documented infections.
Empiric therapy is indicated only in the
presence of life threatening infections,
and should be adjusted or discontinued
based on culture results. Colonization
does not warrant treatment and often
contributes to unnecessary antibiotic use.
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Example: Positive urine culture in patient
with indwelling catheter without clinical
evidence of cystitis or pyelonephritis.
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NCI: Key Issues
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Need reliable specimens for culture:
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No cultures from existing IV lines
If sepsis suspected: Need 2 or more blood
cultures from identified sites, remote from
wounds.
Contaminated culture sites often lead
to misdiagnosis of bacteremia
(“pseudo-bacteremia”); may result in
increased hospital stays, costs, and
morbidity.
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NCI: Key Issues
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Important to consider culture results
(colony counts) and clinical
information: is the patient clinically
infected-signs and symptoms?
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Pathogens of NCI
Enterobacteriaciae: E coli,
Klebsiella, Enterobacter,
Pseudomonas, Proteus, Citrobacter,
Actinobacter, others.
 S aureas: Common nosocomial
pathogen in U.S.
 Coagulase negative Staphylococcus
(S epidermidis).
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Pathogens of NCI
Enterococcus
 C difficile: alarming rise in U.S
 Fungi: Candida- 4th most common
cause of blood stream and urinary
NCI’s; often seen in
immunocompromised host, following
use of broad spectrum antibiotics.
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Prevention of NCI
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Universal precautions: Treat all
patients as if they have a potential
blood-born transmissible disease. All
body secretions/blood must be
handled with care: Body substance
isolation- health care workers to
wear gloves.
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Prevention of NCI
Limit use of urinary catheters, IV lines,
central lines, hyperalimentation lines
and DC at earliest possible time. Use of
specially prepared urinary catheters
(silver alloy) and IV catheters (antibiotic
impregnated) is developing.
 Hand Washing: easiest and most cost
effective means of preventing NCI.
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Important to do even when wearing gloves.
Topical hand antiseptic (alcohol based) is
also very effective.
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Prevention of NCI
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Needle precautions essential to avoid
blood borne infection.
Transmission based precautions:
during care of patients with documented
infection that is important
(epidemiological standpoint), and can be
spread by contact, droplet and airborne
transmission:
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Includes patient isolation, all contacts to
wear gloves, gowns and masks when
indicated.
TB isolation requires negative pressure
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ventilation.
Urinary Tract Infections
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Most common site of NCI in U.S
(35%). Very low mortality (<0.1%)
Bacteremia with gram negative sepsis
increases morbidity and mortality.
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Assess for signs/sx of infection
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Occurs in 3% of patients with nosocomial UTI
Temp, lower abd discomfort, flank pain
Urinalysis, including microscopic
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Urinary Tract Infections
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80% of urinary NCI’s associated with
indwelling urinary catheters. Risk of
bacteremia increases 3.6%/day of
catheterization.
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Bacteriuria without actual infection
(colonization) occurs in 30% of patients
with indwelling catheters. Removal of the
catheter without antibiotic treatment is
adequate treatment.
Pathogens: E.coli, Pseudomonas,
Klebsiella, Candida.
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Nosocomial UTI: Pathophys
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Normally, defense mechanisms help
prevent infections- urine acidity, bladder
emptying and urinary flow.
Bacteria enter via the catheter-migrate in
the lumen and exterior catheter surface.
Important to prevention: closed, sterile
drainage system (eliminate intralumenal
migration). The distal end of the catheter
has a closed connection to a sterile
collection receptacle. Silver impregnated
Foley catheters reduce risk.
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NCI: Bloodstream
Incidence 250,000/yr in the U.S.
Increases hospitalization by avg of 7
days with 62,500 deaths annually.
 These are extremely dangerous
infections that can lead to septic
shock, endocarditis and
osteomyelitis (if Staph aureas) that
can require days to weeks of IV
antibiotic therapy.
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NCI: Bloodstream
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“Secondary” Infections (30-40%):
originate from infections at other body
sites (urinary, surgical site, skin,
pulmonary and others) that “seed” the
circulation.
“Primary” Infections: Blood stream
infections that cannot be attributed to
another body site. Intravascular devices
(IV, central venous catheters, shunts)
are most common source.
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Central line sepsis: incidence 2-3%.
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Pathogens and Pathogenesis
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Pathogens: Staph epidermitis, S aureas,
Enterococcus, Candida, E coli, Klebsiella.
Pathogenesis (primary infection):
migration of organisms from skin
insertion site into the cutaneous tract
along the external surface of the catheter
until the tip is colonized release into
bloodstream.
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Pathogens and Pathophys.
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Clinical presentation: high fevers, shaking
chills, hypotension (gram negative
sepsis), bacterial emboli.
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Septic shock carries a mortality of 40-80%.
Documentation: 2 or more (+) blood
cultures from 2 different anatomic
sites remote from any IV lines, and
never from existing lines.
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Prevention
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Limit use of central lines.
Peripheral veins carry much lower risk of
sepsis. Need to change every 3 days.
Site of Central Lines: Subclavian vein
lowest infection rate compared to Internal
Jugular vein or Femoral vein. Central
lines can be left in place for 7+ days if
maintained adequately.
Remove central line if it is a possible
source of infection and culture tip.
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Prevention
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Catheters impregnated with antibiotics,
chlorhexadine or silver sulfadiazine
reduce rate of “line sepsis” but cost.
Operators must wear masks, gowns and
gloves surgical scrub (central lines)
and site prep with antiseptics like
betadine.
Insertion site should be cleansed daily
with antiseptics (chlorhexadine, betadine,
providine-iodine or alcohol).
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Sepsis “Work-up”
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Suspected clinically by high fevers, chills,
etc. with central line in place.
R/O allergic reaction/drug reaction.
Urine culture, sputum culture if
applicable, and blood cultures from at
least two different sites. Culture any
suspicious skin lesions and surgical
wounds where applicable. Aggressive
culture work-up essential if source not
obvious.
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Sepsis Treatment
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Empiric therapy with broad spectrum
antibiotic(s) pending culture results.
Subsequent antibiotics based on culture
results.
If a secondary source is not obtained and
S aureas sepsis confirmed: parenteral
antibiotics for 2 wks prevent
endocarditis or osteomyelitis.
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