Carbapenamses in Antibiotic Resistance
-
Upload
tummalapalli-venkateswara-rao -
Category
Documents
-
view
228 -
download
5
Transcript of Carbapenamses in Antibiotic Resistance
-
8/9/2019 Carbapenamses in Antibiotic Resistance
1/53
. . .R T V RAO MD
Carbapenamasesin
AntibioticResistance
-
8/9/2019 Carbapenamses in Antibiotic Resistance
2/53
What are Carbapenems
Carbapenems are a class of beta-lactam antibiotics with a broadspectrum of antibacterial activity.
They have a structure that rendersthem highly resistant to beta-
lactamases. Carbapenems
antibiotics were originallydeveloped from thienamycin, anaturally-derived product ofStreptomyces cattleya
-
8/9/2019 Carbapenamses in Antibiotic Resistance
3/53
Carbapenems - Structure
Carbapenems arestructurally verysimilar to the
pencillins, but thesulfur atom inposition 1 of thestructure has
been replacedwith a carbonatom, and hencethe name of the
group, the
-
8/9/2019 Carbapenamses in Antibiotic Resistance
4/53
Drugs belong to the
carbapenem class: Imipenem
Meropenem
Ertapenem
DoripenemPanipenem/ betamipron
-
8/9/2019 Carbapenamses in Antibiotic Resistance
5/53
Background of
Carbapenamases Carbapenem-resistant
Enterobacteriaceae (CRE) areusually resistant to all -lactamagents as well as most otherclasses of antimicrobial agents. The
treatment options for patientsinfected with CRE are very limited.Healthcare-associated outbreaks ofCRE have been reported
-
8/9/2019 Carbapenamses in Antibiotic Resistance
6/53
Discovery of
Carbapenamases In 1996, the first isolate of KPC-producing bacteria was discovered ina clinical specimen ofK pneumoniae
from a hospital in North Carolinainvolved in the Intensive CareAntimicrobial Resistance Epidemiology(ICARE) surveillance program. KPCs
were infrequently isolated until 2001,when KPC-producingEnterobacteriaceae were reported inseveral extended outbreaks in
metropolitan hospitals of New York
-
8/9/2019 Carbapenamses in Antibiotic Resistance
7/53
Carbapenemases are produced byseveral commonly infecting Gram
Negative Bacteria
Carbapenemases are known to exist inseveral different species of gram-negative bacilli including species ofEnterobacteriaceae and Pseudomonasaeruginosa. However,carbapenemases are more common inlactose-fermenting species of
Enterobacteriaceae (e.g., K.pneumoniae and E. coli) than in non-lactose fermenting Enterobacteriaceae(e.g. Serratia marcescens and some
Enterobactericae spp.) and P.aeru inosa.
-
8/9/2019 Carbapenamses in Antibiotic Resistance
8/53
How Carbapenamase
resistance is initiated Carbapenem resistance in
Enterobacteriaceae occurs when an
isolate acquires a carbapenemaseor when an isolate produces anextended-spectrumcephalosporinase, such as an AmpC-
type -lactamase, in combinationwith porin loss. In the United States,the most common mechanism ofcarbapenem resistance is the
Klebsiella pneumoniae
-
8/9/2019 Carbapenamses in Antibiotic Resistance
9/53
Carbapenamases a Global
Problem The resistance toCarbapenems hasemerged worldwide
and thepredominantmechanism ofresistance is
attributed by theproduction ofvariousCarbapenems-
hydrolyzing -
-
8/9/2019 Carbapenamses in Antibiotic Resistance
10/53
Carbapenems used as importantlife saving option
Carbapenems are often used asantibiotics of last resort for treatinginfections due to multidrug-resistant
gram-negative bacilli, because theyare stable even in response toextended-spectrum and AmpC -lactamases. However, gram-negative
bacilli producing the acquired metallo--lactamases (MBLs) IMP and VIMhave been increasingly reported inAsia and Europe and more recently,
they have been detected in Canada
-
8/9/2019 Carbapenamses in Antibiotic Resistance
11/53
Carbapenem Resistance:
MechanismsEnterobacteriaceae Cephalosporinase + porin loss
Carbapenemase
P. aeruginosa Porin loss
Up-regulated efflux
Carbapenemase
Acinetobacterspp. Cephalosporinase + porin loss
Carbapenemase
-
8/9/2019 Carbapenamses in Antibiotic Resistance
12/53
Transposons and Integronscontribute for spread of resistance,
The genes of these
MBL enzymes areoften plasmidborne and areassociated with
mobile geneticelements(transposons andintegrons),
making them
-
8/9/2019 Carbapenamses in Antibiotic Resistance
13/53
CarbapenamasesClassification Enzyme Most Common Bacteria
Class A KPC, SME,IMI, NMC,
GES
Enterobacteriaceae(rare reports in P. aeruginosa)
Class B(metallo- -lactamse)
IMP, VIM,GIM, SPM
P. aeruginosaEnterobacteriaceaAcinetobacterspp.
Class D OXA Acinetobacterspp.
-
8/9/2019 Carbapenamses in Antibiotic Resistance
14/53
Carbapenamases are complex in
Mechanisims Carbapenamases constitute the mostversatile family of -lactamases belongingto molecular classes A, B and D and are
capable of hydrolyzing almost all -lactams.Given their zinc dependent hydrolyticactivity, Carbapenamases of class B isdesignated as metallo--lactamases(MBL) that include, for example, IMP, GIM,
SIM, SPM, and VIM carbapenemases, andthese MBL enzymes have been reported inP.aeruginosa and other multidrug resistant
pathogens
-
8/9/2019 Carbapenamses in Antibiotic Resistance
15/53
Carbapenamases are
spreading faster A new class of bacterial enzymescapable of inactivatingCarbapenems, known as Klebsiella
pneumoniae Carbapenamases(KPCs), has rapidly spread in theUnited States and continues to be
extensively reported elsewhere inthe world. KPCs are class ACarbapenamases that reside ontransferable plasmids and can
hydrolyze all pencillins,
-
8/9/2019 Carbapenamses in Antibiotic Resistance
16/53
Klebsiella pneumoniaeCarbapenamases
KPC-producing organisms continuesto evolve. Although most KPCs aredetected in isolates ofKlebsiella
and Escherichia coli, KPCs havebeen extensively reported in othergenera of the Enterobacteriaceae
family, such as Proteus,
Serratia, Salmonella, andCitrobacter.
-
8/9/2019 Carbapenamses in Antibiotic Resistance
17/53
Located on plasmids; conjugative andnonconjugative
blaKPC is usually flanked by transposonsequences
blaKPC reported on plasmids with:
Normal spectrum -lactamases Extended spectrum -lactamases Aminoglycoside resistance
K le b sie lla p n e u m on iaeC arb ap en am ases
-
8/9/2019 Carbapenamses in Antibiotic Resistance
18/53
Emerging Carbapenem Resistance
in Gram-Negative Bacilli Significantly limits treatment options for
life-threatening infections
No new drugs for gram-negative bacilli
Emerging resistance mechanisms,carbapenemases are mobile,
Detection of carbapenemases andimplementation of infection controlpractices are necessary to limit spread
-
8/9/2019 Carbapenamses in Antibiotic Resistance
19/53
KPCs in
EnterobacteriaceaeSpecies CommentsKlebsiella spp. K.pneumoniae-cause of outbreaks
K.oxytoca-sporadic occurrence
Enterobacterspp. Sporadic occurrenceEscherichia coli
Salmonella spp.
Citrobacter freundii
Serratia spp.
Pseudomonas aeruginosa Columbia & Puerto Rico
-
8/9/2019 Carbapenamses in Antibiotic Resistance
20/53
Pseudomonas aeruginosaCarbapenamases
KPC resistance hasbeen reported ininherently
resistantorganisms suchas
Pseudomon
as from Trinidad,an isolate ofmultidrug-resistant
Pseudomonasaeruginosa that
-
8/9/2019 Carbapenamses in Antibiotic Resistance
21/53
Special antibiotic sensitivity testing isemerging need in Microbiology
laboratories Supplemental
testing, inaddition to the
routinesusceptibilitytests of isolates,has becomenecessary inorder to detectthe deluge ofbeta-lactamasesand
carbapenemases
-
8/9/2019 Carbapenamses in Antibiotic Resistance
22/53
When to Suspect a KPC-
Producers Enterobacteriaceae especiallyKlebsiella pneumoniae that areresistant to extended-spectrum
cephalosporins:
MIC range for 151 KPC-producingisolates
Ceftazidime 32 to >64 g/ml Ceftriaxone 64 g/ml
Cefotaxime 64 g/ml
Variable susceptibility to cefoxitin and
-
8/9/2019 Carbapenamses in Antibiotic Resistance
23/53
Modified HodgeTest for
CarbapenemaseDetection in
Enterobacteriacea
-
8/9/2019 Carbapenamses in Antibiotic Resistance
24/53
The Modified Hodge
TestThe Modified Hodge Test is aphenotypic confirmatory test forCarapnemase activity and is
indicated when there is a positivescreening test and resistance to oneor more agents in cephalosporin
subclass III (i.e., cefoperazone,cefotaxime, ceftazidime, ceftizoxime,and ceftriaxone) Be aware thatimipenem disk tests perform poorly as
a screen for carbapenemases.
-
8/9/2019 Carbapenamses in Antibiotic Resistance
25/53
CLSI Recommends
CLSI Recommends doing ModifiedHodge test before reportingCarbapenam susceptibility results
if results are elevated butsusceptible to Carbapenam byMinimum inhibitory concentration.
The results ofintermediate orresistance to Carbapenems neednot be tested with MHT
-
8/9/2019 Carbapenamses in Antibiotic Resistance
26/53
The Modified Hodge Test
(MHT) The Modified Hodge Test (MHT)
detects carbapenemase productionin isolates of Enterobacteriaceae
Carbapenemase production isdetected by the MHT when the test
isolate produces the enzyme andallows growth of a carbapenemsusceptible strain (E.coli ATCC25922) towards a carbapenem disk
-
8/9/2019 Carbapenamses in Antibiotic Resistance
27/53
The Carapnemase is detected byantibiotic sensitivity patterns
Carbapenemaseproduction isdetected by theMHT when the testisolate producesthe enzyme andallows growth of acarbapenem
susceptible strain(E.coli ATCC25922) towards acarbapenem disk.
The result is a
characteristiccloverleaf-like
-
8/9/2019 Carbapenamses in Antibiotic Resistance
28/53
Step 1 and 2 of MHT
Prepare a 0.5
McFarlanddilution of theE.coli ATCC25922 in 5 ml ofbroth or saline.
Dilute 1:10 byadding 0.5 ml ofthe 0.5 McFarlandto 4.5 ml of MHB
or saline.
-
8/9/2019 Carbapenamses in Antibiotic Resistance
29/53
Step 3 and 4 of MHT
Streak a lawn of the1:10 dilution ofE.coli ATCC 25922
to a Mueller Hintonagar plate andallow to dry 35minutes.
Place a 10 gmeropenem orertapenemsusceptibility diskin the center of thetest area.
-
8/9/2019 Carbapenamses in Antibiotic Resistance
30/53
Protocols in Modified HodgeTest
-
8/9/2019 Carbapenamses in Antibiotic Resistance
31/53
K.pneumonia showingCarbapenem resistance
-
8/9/2019 Carbapenamses in Antibiotic Resistance
32/53
Step 5 and 6 of MHT
In a straight line, streak test organismfrom the edge of the disk to theedge of the plate. Up to four
organisms can be tested on thesame plate with one drug.
Incubate overnight at 35OC 2OC in
ambient air for 1624 hours
Modified Hodge Test
-
8/9/2019 Carbapenamses in Antibiotic Resistance
33/53
Modified Hodge Test
Lawn ofE. coliATCC 259221:10 dilution of a0.5 McFarland suspension
Imipenem disk
Test isolates
. , , - .Described by Lee et al CMI 7 88 102.2001
-
8/9/2019 Carbapenamses in Antibiotic Resistance
34/53
Observation for
Carbapenamases detectionby HMT After 1624 hours
of incubation,
examine theplate for a cloverleaf-typeindentation at the
intersection ofthe test organismand the E. coli25922, within the
zone of inhibition
of the
-
8/9/2019 Carbapenamses in Antibiotic Resistance
35/53
MHT detection (photo courtesy of CDC)
The MHT performedon a 100 mmMHA plate. (1) K.
pneumoniaeATCCBAA 1705,
positive result K.pneumoniaeATCC
BAA 1706,negative result;and a clinicalisolate, positive
result312
-
8/9/2019 Carbapenamses in Antibiotic Resistance
36/53
A Positive HMT test
MHT Positive testhas a clover leaf-like indentationof the E.coli25922 growingalong the testorganism growthstreak within the
disk diffusionzone. A positive MHT
indicates thatthis isolate is
producing a
-
8/9/2019 Carbapenamses in Antibiotic Resistance
37/53
A negative HMT Test
MHT Negative test has no growthof the E.coli 25922 along thetest organism growth streakwithin the disc diffusion.
A negative MHT indicatesthat this isolate is notproducing a
carbapenemase
-
8/9/2019 Carbapenamses in Antibiotic Resistance
38/53
Quality control strains in
Modified Hodge test Perform quality control of the
Carbapenems disks according toCLSI guidelines.
Perform quality control with each run.
MHT Positive Klebsiella
pneumoniae ATCC BAA-1705 MHT Negative Klebsiella
pneumoniae ATCC BAA-1706
-
8/9/2019 Carbapenamses in Antibiotic Resistance
39/53
CLSI guidelines for
Carbapenamases detection CLSI has published guidelines fordetection of isolates producingcarbapenemases (CLSI document
M100) . For isolates that testsusceptible to a carbapenem butdemonstrate reduced susceptibilityeither by disk diffusion or MICtesting, performing a phenotypictest for carbapenemase activity, theModified Hodge Test (MHT), is
recommended
-
8/9/2019 Carbapenamses in Antibiotic Resistance
40/53
Testing with ertapenem ormeropenem
The procedure described by Landman etal. describes using a 10-g imipenem
disk for step 1. However, there arespecies of Enterobacteriaceae whichhave intrinsic mechanisms ofresistance to imipenem other than a
carbapenemase (See CLSI documentM100, Appendix G). Therefore,ertapenem or meropenem mayprovide more specific selection foracquired carbapenem resistance in
Enterobacteriaceae
-
8/9/2019 Carbapenamses in Antibiotic Resistance
41/53
New CLSI
guidelinesNonsusceptibleInterpretive
Category
-
8/9/2019 Carbapenamses in Antibiotic Resistance
42/53
NonsusceptibleInterpretive Category
. used for organisms that haveonly a susceptible interpretivecategory, but not intermediate
or resistant interpretivecategories (ie, susceptible-onlyinterpretive category). Asusceptible-only interpretive
category may be applied to newantimicrobial agents for whichno resistant isolates have beenencountered at the time the
initial interpretive criteria are
-
8/9/2019 Carbapenamses in Antibiotic Resistance
43/53
NonsusceptibleInterpretive Category
The isolates that test with an MICabove the susceptible interpretivebreakpoint are designated as
nonsusceptible. A designation ofnonsusceptible does notnecessarily mean that aresistance mechanism exists in
the isolate. The MIC of the isolatein the nonsusceptible range maybe within the previouslyrecognized wild-type distribution
of susceptibility results; however,
-
8/9/2019 Carbapenamses in Antibiotic Resistance
44/53
Interpretation/ResultsConveyed to Infection Control Departments
Report all culturesthat are positivefor CRE or
carbapenemase-producingEnterobacteriaceae to the
appropriateinfection controlpersonnel.
-
8/9/2019 Carbapenamses in Antibiotic Resistance
45/53
Patients infected will be dealt withcaution to prevent spread
patients colonized with carbapenem-resistant or Carbapenamases-
producing Enterobacteriaceae inthe intestinal tract and the Patientswho grow these organisms should
be placed on Contact Precautionsto prevent transmission of theresistant bacteria
Laboratories should create
-
8/9/2019 Carbapenamses in Antibiotic Resistance
46/53
Laboratories should createprotocols for detection of CRE
The exact procedure for confirmationof CRE or carbapenemase-
production should be laboratory-specific and chosen based uponlaboratory workflow and the typesof isolates causing clinical infections
in the patient population served. Itmay be helpful to refer to the CLSIguidelines for identification ofcarbapenemase production in
isolates that test susceptible to
-
8/9/2019 Carbapenamses in Antibiotic Resistance
47/53
Follow contact Precautions
ContactPrecautionsshould be
implemented forall patients withpositive culturesfor CRE or
carbapenemase-producingEnterobacteriaceae
-
8/9/2019 Carbapenamses in Antibiotic Resistance
48/53
Hand washing can saveseveral patients
-
8/9/2019 Carbapenamses in Antibiotic Resistance
49/53
Care of the patients colonized withCarapnemase resisistant
Enterobactericae Patients colonized with CRE are
thought to be a source oftransmission in the healthcare
setting . Identifying patients whoare colonized with CRE and placingthese patients in isolationprecautions may be an importantstep in preventing transmission
-
8/9/2019 Carbapenamses in Antibiotic Resistance
50/53
Detection of Antibiotic resistancepatterns is more than past
Resistance to our beta-lactam andcarbapenem antibiotics is becomingdaunting for antimicrobial therapy
for infections involving theEnterobacteriaceae. Similarly,laboratory testing to detect theseresistance mechanisms is becomingmore complex and perplexing formicrobiology laboratories.
-
8/9/2019 Carbapenamses in Antibiotic Resistance
51/53
Automation has limited usein Carbapenamases detection Automated testing
alone will notdetect all of theresistance patterns
that occur viabeta-lactamasesandcarbapenemases.Failure to detectorganisms withthese enzymes canresult in erroneousreports that wouldindicate an isolateis susceptible tobeta-lactam and/or
-
8/9/2019 Carbapenamses in Antibiotic Resistance
52/53
Detection of Drug resistance helps tocontrol the spread of Hospital acquired
infections In addition to the riskof compromisedcare of the patient,when pathogens
with theseenzymes goundetected,necessaryinfection controlmeasures areprecluded, therebyallowing the risk ofthese resistant
organisms
-
8/9/2019 Carbapenamses in Antibiotic Resistance
53/53
Created by Dr.T.V.Rao MD fore learning in
Microbiology
Email [email protected]