Date post: | 07-Apr-2018 |
Category: |
Documents |
Upload: | tummalapalli-venkateswara-rao |
View: | 225 times |
Download: | 0 times |
of 38
8/6/2019 Enterobacter Nosocomial infections
1/38
Dr.T.V.Rao MD
ENTEROBACTERAN EMERGING NOSOCOMIAL PATHOGEN
DR.T.V.RAO MD 1
8/6/2019 Enterobacter Nosocomial infections
2/38
Enterobacteris a genus of common
Gram-negative, facultatively-
anaerobic, rod-shaped bacteria
of the family Enterobacteriaceae.
Several strains of the these
bacteria are pathogenic andcause opportunistic infections in
immunocompromised (usually
hospitalized) hosts and in those
who are on mechanical
ventilation. The urinary andrespiratory tract are the most
common sites of infection. It is
also a fecal coliform, along with
Escherichia.
ENTEROBACTER LEADING CAUSE OF
OPPORTUNISTIC INFECTIONS
DR.T.V.RAO MD 2
8/6/2019 Enterobacter Nosocomial infections
3/38
Enterobacteris a gram-
negative bacillus that
belongs to the
Enterobacteriaceae family.
Other members of thisfamily include Klebsiella,
Escherichia, Citrobacter,
Serratia, Salmonella, and
Shigella species, amongmany others.
ENTEROBACTER IS A
ENTEROBACTERIACEAE
DR.T.V.RAO MD 3
8/6/2019 Enterobacter Nosocomial infections
4/38
BACKGROUND OF ENTEROBACTER SPECIES
Enterobacterspecies, particularly Enterobacter cloacae
and Enterobacter aerogenes, are important nosocomial
pathogens responsible for various infections, including
bacteremia, lower respiratory tract infections, skin andsoft-tissue infections, urinary tract infections (UTIs),
endocarditis, intra-abdominal infections, septic arthritis,
osteomyelitis, and ophthalmic infections. Enterobacter
species can also cause various community-acquiredinfections, including UTIs, skin and soft-tissue
infections, and wound infections, among others
DR.T.V.RAO MD 4
8/6/2019 Enterobacter Nosocomial infections
5/38
OTHER SPECIES OF
ENTEROBACTER
The most commonly isolated species includeE cloacae and E aerogenes, followed by E sakazakii(recently reclassified into theAchromobactergenus, which produces a characteristic yellow pigment.Other species rarely encountered in the laboratoryinclude Enterobacter asburiae, Enterobacter gergoviae,Enterobacter taylorae, Enterobacter hormaechei, andEnterobacter cancerogenus. Enterobacter agglomerans
has been removed from the genus Enterobacterandrenamed Pantoea agglomerans.
DR.T.V.RAO MD 5
8/6/2019 Enterobacter Nosocomial infections
6/38
Enterobacter
aerogenesis a
Gram-negative,
oxidase negative,
catalase positive,
citrate positive,
indole negative, rod-shaped bacterium.
ENTEROBACTER AEROGENES -
CHARACTERISTICS
DR.T.V.RAO MD 6
8/6/2019 Enterobacter Nosocomial infections
7/38
E. aerogenes is part of
the flora found in the
human intestines. As an
opportunistic pathogenit may infect immuno-
compromised patients
in the urinary and
respiratory tracts. Itrarely infects healthy
people
ENTEROBACTER AEROGENES IS PART OF
NORMAL FLORA CAN BE INFECTIVE
DR.T.V.RAO MD 7
8/6/2019 Enterobacter Nosocomial infections
8/38
DR.T.V.RAO MD 8
8/6/2019 Enterobacter Nosocomial infections
9/38
E. aerogenesis a nosocomial
and pathogenic bacterium that
causes opportunistic infections
including most types of
infections. Enterobacterspecies
can also cause various
community-acquired infections.
Some strains can become very
treatment resistant, a result of
their colonization within hospital
environments. However, themajority are sensitive to most
antibiotics designed for this
bacteria class.
ENTEROBACTER AEROGENESIMPORTANT
NOSOCOMIAL PATHOGEN
DR.T.V.RAO MD 9
8/6/2019 Enterobacter Nosocomial infections
10/38
Some of the infections caused by
E. aerogenesresult from
specific antibiotic treatments,
venous catheter insertions,
and/or surgical procedures. E.
aerogenes is generally found in
the human gastrointestinal tract
and does not generally cause
disease in healthy individuals. It
has been found to live in various
wastes, hygienic chemicals, andsoil.
SOURCE OF ENTEROBACTER
INFECTIONS
DR.T.V.RAO MD 10
8/6/2019 Enterobacter Nosocomial infections
11/38
Although community-acquired
Enterobacterinfections are
occasionally reported,
nosocomial Enterobacter
infections are, by far, mostcommon. Patients most
susceptible to Enterobacter
infections are those who stay
in the hospital, especially the
ICU, for prolongedperiods
PROLONGED STAY IN HOSPITAL PREDISPOSES TO
ENTEROBACTER INFECTIONS
DR.T.V.RAO MD 11
8/6/2019 Enterobacter Nosocomial infections
12/38
Other major risk factors ofEnterobacterinfection includeprior use of antimicrobial agents,concomitant malignancy(especially hemopoietic and
solid-organ malignancies),hepatobiliary disease, ulcers ofthe upper gastrointestinal tract,use of foreign devices such asintravenous catheters, andserious underlying conditions
such as burns, mechanicalventilation, andimmunosuppression.
OTHER PREDISPOSING FACTORS
DR.T.V.RAO MD 12
8/6/2019 Enterobacter Nosocomial infections
13/38
The source of infection
may be endogenous
(via colonization of the
skin, gastrointestinaltract, or urinary tract) or
exogenous, resulting
from the ubiquitous
nature ofEnterobacterspecies
ENDOGENOUS SOURCE
MAJOR SOURCE OF INFECTION
DR.T.V.RAO MD 13
8/6/2019 Enterobacter Nosocomial infections
14/38
These bacteria have an
outer membrane that
contains, among other
things, lipopolysaccharides
from which lipid-A plays amajor role in sepsis. Lipid-
A, also known as
endotoxin, is the major
stimulus for the release ofcytokines, which are the
mediators of systemic
inflammation and its
complications.
PATHOPHYSIOLOGY
DR.T.V.RAO MD 14
8/6/2019 Enterobacter Nosocomial infections
15/38
Multiple reports have
incriminated the hands of
personnel, endoscopes, blood
products, devices for monitoring
intra-arterial pressure, and
stethoscopes as sources of
infection. Outbreaks have been
traced to various common
sources: total parenteral nutrition
solutions, isotonic saline
solutions, albumin, digitalthermometers, and dialysis
equipment.
IMPORTANT OTHER SOURCES
DR.T.V.RAO MD 15
8/6/2019 Enterobacter Nosocomial infections
16/38
Enterobacterspecies contain a
subpopulation of organisms that
produce a beta-lactamase atlow-levels. Once exposed to
broad-spectrum cephalosporins,
the subpopulation of beta-
lactamaseproducing organisms
predominate. Thus, an
Enterobacterinfection that
appears sensitive to
cephalosporins at diagnosis mayquickly develop into a resistant
infection during therapy
ENTEROBACTER PRODUCE BETA
LACTAMASES
DR.T.V.RAO MD 16
8/6/2019 Enterobacter Nosocomial infections
17/38
The most important test to
document Enterobacter
infections is culture. Direct
Gram staining of the
specimen is also veryuseful because it allows
rapid diagnosis of an
infection caused by gram-
negative bacilli and helps inthe selection of antibiotics
with known activity against
most of these bacteria
MICROBIOLOGICAL STUDIES
DR.T.V.RAO MD 17
8/6/2019 Enterobacter Nosocomial infections
18/38
8/6/2019 Enterobacter Nosocomial infections
19/38
MICROSCOPY AND CULTURING HELPS IN
DIAGNOSIS
DR.T.V.RAO MD 19
8/6/2019 Enterobacter Nosocomial infections
20/38
Grown on eosin
methylene blue
(EMB) agar. EMBagar contains the
indicator dyes
eosin andmethylene blue.
AS GROWN ON EOSIN METHYLENE BLUE
MEDIUM
DR.T.V.RAO MD 20
8/6/2019 Enterobacter Nosocomial infections
21/38
Oxoid has introduced
Oxoid Chromogenic
Enterobacter sakazakii
Agar (Druggan-Forsythe-Iversen (DFI)
formulation) that allows
recovery and detection
ofE. sakazakiiin just 3days 2 days faster
than by conventional
methods
FASTER DETECTION WITH OXOID CHROMOGENIC
ENTEROBACTER SAKAZAKII AGAR (DRUGGAN-FORSYTHE-
IVERSEN (DFI) FORMULATION
DR.T.V.RAO MD 21
8/6/2019 Enterobacter Nosocomial infections
22/38
This innovative new
chromogenic medium
contains the substrate 5-
bromo-4-chloro-3-indolyl-,
D-glucopyranoside which iscleaved by the enzyme -
glucosidase, expressed by
E. sakazakii, to form easily
distinguishable blue-greencolonies.
OXOID CHROMOGENIC ENTEROBACTER
SAKAZAKII AGAR
DR.T.V.RAO MD 22
8/6/2019 Enterobacter Nosocomial infections
23/38
Merck's new ChromoCultEnterobacter sakazakii Agar willincrease the security in detectingthis microorganism in milk powderand infant formula.
Based on the alpha-D-Glucosidase -
an enzyme specific forE. sakazakii-only the colonies ofE. sakazakiiappear turquoise while otherbacteria grow colourless.ChromoCult Enterobactersakazakii Agar allows a fast andreliable detection within only 24hours with no further confirmationstep.
MERCK'S NEW CHROMOGENIC MEDIUM FOR
DETECTION OF ENTEROBACTER SAKAZAKII
DR.T.V.RAO MD 23
8/6/2019 Enterobacter Nosocomial infections
24/38
Two sets (with one aerobic and
one anaerobic bottle in each set)
should be obtained 20-30
minutes apart, from 2 different
sites (if possible). If the patient
has a central venous catheter,one set should be drawn through
it. In the adult patient, 8-10 mL of
blood should be collected in each
bottle. Enterobacteriaceae
ferment glucose and should thusgrow in both bottles.
BLOOD CULTURE FOR IDENTIFICATION
DR.T.V.RAO MD 24
8/6/2019 Enterobacter Nosocomial infections
25/38
Penicillin's should include
ampicillin and at least one
of the extended-spectrum
penicillin's (eg, carboxy,
ureido, oracylaminopenicillin) such
as ticarcillin, mezlocillin, or
piperacillin. The addition of
ticarcillin-clavulanic acid orpiperacillin-tazobactam is
optional.
DRUGS TO INCLUDE FOR ANTIMICROBIAL
SUSCEPTIBILITY TESTING
DR.T.V.RAO MD 25
8/6/2019 Enterobacter Nosocomial infections
26/38
CHOOSING A RIGHT ANTIBIOTIC
Cephalosporins include a first-generation drug of this class of
antibiotics, such as cefazolin, and a third-generation drug with
and without Pseudomonas activity, such as ceftriaxone or
ceftazidime.
Include at least one carbapenem, usually imipenem, or inaccordance with available pharmaceutical agents in the
institution.Include the aminoglycosides, usually gentamicin and
tobramycin.
Amikacin may be tested primarily or when bacteria showresistance to these 2 drugs. Include a quinolone, such as
ciprofloxacin.Include TMP-SMZ.Some laboratories routinely add
aztreonam.
DR.T.V.RAO MD 26
8/6/2019 Enterobacter Nosocomial infections
27/38
8/6/2019 Enterobacter Nosocomial infections
28/38
DR.T.V.RAO MD 28
8/6/2019 Enterobacter Nosocomial infections
29/38
Hyper production (stable DE
repression) of AmpC beta-
lactamases associated with
some decrease in permeability to
the carbapenems may also
cause resistance to theseagents. In vitro low-level
ertapenem resistance was not
associated with resistance to
imipenem or meropenem, but
high-level ertapenem resistancepredicted resistance to the other
carbapenems
CARBAPENEMS TOO ARE BECOMINGRESISTANT
DR.T.V.RAO MD 29
8/6/2019 Enterobacter Nosocomial infections
30/38
Colistin and polymyxin B: These
drugs are being used more
frequently to treat serious
infection caused by multidrug-
resistant organisms, sometimes
as monotherapy or incombination with other
antibiotics. Clinical experience,
including documentation of
success rates and attributable
mortality is broadening
COLISTIN AND POLYMYXIN B ARE GAINING
IMPORTANCE IN TREATMENTS
DR.T.V.RAO MD 30
8/6/2019 Enterobacter Nosocomial infections
31/38
The fourth-generation
cephalosporins are
relatively stable to the
action of AmpC beta-
lactamases; consequently,they retain moderate
activity against the mutant
strains ofEnterobacter,
hyper producing AmpCbeta-lactamase
4 TH GENERATION CEPHALOSPORINS ARE A
CHOICE
DR.T.V.RAO MD 31
8/6/2019 Enterobacter Nosocomial infections
32/38
Other antibiotics that
may be considered
for testing include
tigecycline,polymyxin B, and
colistin, the latter two
when particularlyresistant organisms
are identified
OTHER NEW GENERATION OF ANTIBIOTICS
DR.T.V.RAO MD 32
8/6/2019 Enterobacter Nosocomial infections
33/38
Enterobacter sakazakiihas been reported as a cause of
sepsis and meningitis,
complicated by ventriculitis, brain
abscess, cerebral infarction, and
cyst formation.[ This clinical
pattern appears to be specific to
E sakazakiiin neonates and
infants infected with this
bacterium. E sakazakiihas also
been associated with manyoutbreaks due to contaminated
powdered formula for infants
Enterobacter sakazakii
ENTEROBACTER SAKAZAKII
A IMPORTANT SPECIES
DR.T.V.RAO MD 33
8/6/2019 Enterobacter Nosocomial infections
34/38
The bacteria designated by the acronym
SERMOR-PROVENF (SER = Serratia,MOR = Morganella, PROV = Providencia,
EN = Enterobacter, F = freundii for
Citrobacter freundii) have similar,
although not identical, chromosomal
beta-lactamase genes that are inducible.With Enterobacter, the expression of the
geneAmpCis repressed, but
derepression can be induced by beta-
lactams. Of these inducible bacteria,
mutants with constitutive hyperproduction
of beta-lactamases can emerge at a rate
between 105 and 108. These mutants are
highly resistant to most beta-lactam
antibiotics and are considered stably
derepressed.
SERMOR-PROVENF
DR.T.V.RAO MD 34
8/6/2019 Enterobacter Nosocomial infections
35/38
The National Healthcare
Safety Network (NHSN)
reported on healthcare-
associated infections (HAI)
between 2006 and 2007.They found Enterobacter
species to be the eighth
most common cause of HAI
(5% of all infections) andthe fourth most common
gram-negative cause of
HAIs.[
THE NATIONAL HEALTHCARE SAFETY NETWORK
(NHSN) REPORTS ON ENTEROBACTER
DR.T.V.RAO MD 35
8/6/2019 Enterobacter Nosocomial infections
36/38
HAND WASHING STILL REDUCES SPREAD OF
ENTEROBACTER IN THE HOSPITAL ENVIRONMENT
DR.T.V.RAO MD 36
8/6/2019 Enterobacter Nosocomial infections
37/38
DR.T.V.RAO MD 37
FOR ARTICLES OF INTEREST ON INFECTIOUS
DISEASES FOLLOW ME ON
8/6/2019 Enterobacter Nosocomial infections
38/38
Created by Dr.T.V.Rao MD for e learning
resources for Microbiologists in Developing
World Email
DR T V RAO MD 38