Presentation on theme: "Extended-spectrum β-lactamase (ESBL) Production in Enterobacteriaceae"— Presentation transcript:
1Extended-spectrum β-lactamase (ESBL) Production in Enterobacteriaceae Daniel Garang Kuir.BBioMedSci, USQM App Sci (MedSci), RMIT
2What are Enterobacteriaceae? Members of Enterobacteriaceae family are a heterogeneous group of gram negative bacteria.Are part of human’s normal enteric flora.Are also abundantly distributed in nature.Include some prominent, often opportunistic, human pathogens;Such as E. coli (e.g uropathogenic E. coli), Klebsiella spp, Enterobacter spp, Citrobacter spp, Salmonella spp, Shigella spp, Yersinia pestis, Serratia marcescens, Proteus spp, Morganella spp, & Providencia spp.Majority are often expediently termed as the “ESCPPM” organisms – which stands for Enterobacter spp, Serratia spp, Citrobacter freundii, Proteus vulgaris & penneri, Providencia spp, & Morganella morganii .Several members of this group are ESBL - &/or AmpC- producers.K. pneumoniae & E. coli are major producers of ESBLs in this group of gram negative bacteria.
3What are Enterobacteriaceae? Contd.. Production of β-lactamases in Enterobacteriaceae is a common mechanism of antimicrobial resistance.These β-lactamases include the novel β-lactamases such as ESBLs, AmpC…etc, & others such as;Penicillinase, cephalosporinase, broad-spectrum, extended-spectrum, carbapenemase.AmpC β-lactamases are chromosomally encoded cephalosporinases (chromosomal bla genes).AmpC are expressed in many Enterobacteriaceae and other organisms.AmpC induce, by constitutive hyperproduction or mutation, wide-ranging resistance to first-, second-, and third- generation cephalosporins, most penicillins, and beta- lactam/beta-lactam-inhibitor (BL/BLI) combinations.
4Mechanisms of antimicrobial resistance in Enterobacteriaceae Production of novel β-lactamases e.g. ESBLs, AmpC;In tandem with production of β-lactamases, Enterobacteriaceae employ other mechanisms of resistance such as;enzymatic inactivation;efflux pumps;outer membrane porin loss;target modifications;transfer or acquisition of new genetic material, ormutations – ESBLs are essentially derivative enzymes acquired through mutations - substitution or deletion of amino acids - in progenitor β- lactamases (e.g TEM, SHV or CTX-M).
5What are ESBLs?ESBLs are novel β-lactamases - are newer β-lactamases of pathogenic gram negative bacteria (esp. Enterobacteriaceae family).These novel β-lactamases also include;Plasmid-mediated AmpC β-lactamases;Carbapenem-hydrolysing β-lactamases (e.g. Klebsiella pneumoniae carbapenemases (KPC));Β-lactamases with reduced sensitivity to β-lactamases inhibitorsDefinition: ESBLs are bacterial enzymes capable of hydrolysing and thus conferring resistance to all penicillins, first-, second-, & third- generation cephalosporins, and aztreonam.And are inhibited by β-lactamase inhibitors such as clavulanic acid, sulbactam and tazobactam.ESBLs are plasmid-mediated enzymes that confer multi-drug resistance to gram negative bacteria.ESBLs may be co-expressed &/or co-transmitted with chromosomally- encoded AmpC β-lactamases – thus presence of ESBLs may be masked by AmpC.
6What are ESBLs? contd..ESBLs hydrolyse all β-lactam antibiotics – penicillins and cephalosporins.β-lactamases possess either a serine moiety or a zinc atom in the active site,Either of which is vital for hydrolysis of the β-lactam ring of a β–lactam antibiotic.ESBLs are diverse, quickly evolving & therapeutically difficulty to eradicate.ESBL production in Enterobacteriaceae also render them resistant to other major classes of antibiotics such as;Fluoroquinolones (e.g. ciprofloxacin, norfloxacin),Aminoglycosides (e.g. gentamicin, tobramycin, amikacin)Tetracyclines (e.g. tetracycline)Trimethroprims-sulfamethoxazole (Cotrimoxazole)Other antibiotic classesNB : β-lactamase production, co-expression of ESBL &/or AmpC, carriage of other resistance gene on the same plasmid account for multidrug resistance in this group of bacteria.ESBL-mediated extensive antimicrobial resistance poses public health risks.ESBL-producing Enterobacteriaceae are essentially multidrug resistant bacteria.
7βeta-lactam ring & the hydrolysing action of β-lactamases Source: Rosário NA, Grumach AS. Allergy to beta-lactams in paediatrics: a practical approach. J Pediatr (Rio J). 2006;82(5 Suppl):S181-8.
8Transmission of resistance genes between bacterial species. Source: Partridge, S. (2014). Movement of resistance genes in hospitals. Microbiology Australia.
9Clinical significance of ESBL-producing Enterobacteriaceae (ESBL-PE) ESBL-producing Enterobacteriaceae (ESBL-PE) cause significant mortality and morbidity globally.ESBL-PE cause a range of infections including uncomplicated UTIs, life- threatening bacteraemia, URTIs, gastroentritis, & colonising wound infections.Mortality of patients with ESBL +ve sepsis is significantly higher than those with ESBL -ve sepsis – up to 30% of GNB-caused sepsis is fatal.Are implicated in large scale outbreaks in hospital or community settings.Cause localised or institutionalised outbreaks.Infections caused by ESBL-PE are associated with rising healthcare cost.Decreased productivity as a consequence of prolonged hospitalisation.ESBL-PE are associated with increasing episodes of clinical treatment failure.
10Clinical significance of ESBL-producing Enterobacteriaceae (ESBL-PE) contd… ESBL producing organisms have important therapeutic and clinical ramifications for patients from whom they are isolated.ESBL-PE pose significant public health risks.ESBL-PE pose serious infection control challenges.ESBL production in Enterobacteriaceae has been a consequence of widespread use of broad spectrum antibiotics in hospital settings.Increasing prevalence is reported in isolates recovered from community- based patients.ESBLs are transferrable via conjugative plasmids thus dissemination of resistance genes among bacterial populations can occur and spread in larger geographic regions.Treatment of ESBL-PE involves a combination of antibiotics, some of which have undesirable side effects including nephrotoxicity.
11Risk factors for infections with ESBL-producing Enterobacteriaceae Risk factors for infections with ESBL-PE in healthcare- or community-acquired infections include;Previous use of antibiotics including broad spectrum antibiotics e.g 3GC cephalosporins;Recent or prolonged hospital admissions including admissions to ICU;Recurrent UTIs;Empiric antibiotic therapyIncreased age; female gender; institutionalised residential care e.g. nursing homes;Intravenous therapy;International travels to areas of established endemicity e.g India subcontinent, the Middle East and Africa;Immunosuppressive chemotherapy;Invasive procedures- indwelling urinary catheters; central venous catheter, andUnderlying comorbidities such as chronic renal insufficiencies, haemodialysis, liver disease, diabetes mellitus, malignancy, hypertension, heart disease, neutropenia, and HIV infection
12Classification of β-lactamases ESBLs were first reported in Germany in 1983.This followed introduction of broad spectrum 3G cephalosporins into clinical use.ESBLs have been reported in all parts of the world – except Antarctica.ESBLs are derivatives of classic β-lactamases eg SHV-2 is derived from SHV-1.ESBLs are occasioned by single mutations in progenitor (parent) enzymesA mutation of few amino acids.ESBLs exhibit fundamental changes in substrate spectra, substrate profile , reactions to inhibitors & isoelectric point – important distinguishing factors.Over 200 ESBLs are characterised & classified – there is still no consensus on exact figure.Β-lactamases have been variously classified over time.Two commonly used classification schemes are;Ambler molecular classification systemBush-Jacoby-Medeiros functional classification system.
13Classification of β-lactamases contd… The Ambler molecular system classifies β-lactamases on the basis of protein homology (amino acid similarities);4 major classes (A, B, C & D).The Bush-Jacoby-Medeiros functional system classifies β- lactamases, on the basis of functional similarities/substrate and profile inhibitor profile;4 main groups (1, 2, 3 & 4).ESBLs are derived from group 2be β-lactamases;the `e’ of 2be denotes the extended-spectrum capability of the newly derived enzyme.ESBLs are quite diverse.Clinically important ESBLs are derived from 3 major types of classic beta-lactamases; TEM-, SHV-, & CTX-M-type β- lactamases.Temoniera – a Greek patient from whom this ESBL type was first isolated.SHV - Sulfhydryl Variable.CTX-M - Cefotaxime – Munich (first isolated in Munich)
15Classification of β-lactamases contd… Snapshot of major ESBLs – SHV -, TEM- & CTX-M-types including rare and peculiar ESBLs
16Functional group or subgroup Representative enzymes Classification of β-lactamases contd… Major classes of β-lactamases of clinical significanceEnzyme familyFunctional group or subgroupNo. of enzymesRepresentative enzymesCMY1, 1e50CMY-1 to CMY-50TEM2b, 2be, 2br, 2ber1722b12TEM-1, TEM-2, TEM-132be79TEM-3, TEM-10, TEM-262br36TEM-30 (IRT-2), TEM-31 (IRT-1), TEM-1632ber9TEM-50 (CMT-1), TEM-158 (CMT-9)SHV2b, 2be, 2br12730SHV-1, SHV-11, SHV-8937SHV-2, SHV-3, SHV-1155SHV-10, SHV-72CTX-M90CTX-M-1, CTX-M-44 (Toho-1) to CTX- M-92PERPER-1 to PER-5VEBGES2f715VEB-1 to VEB-7GES-2 to GES-7 (IBC-1) to GES-15KPCKPC-2 to KPC-10SME3SME-1, SME-2, SME-3OXA2d, 2de, 2df1582dOXA-1, OXA-2, OXA-102de2df48OXA-11, OXA-14, OXA-15OXA-23 (ARI-1), OXA-51, OXA-58IMP3a26IMP-1 to IMP-26VIM23VIM-1 to VIM-23IND8IND-1, IND-2, IND-2a, IND-3 to IND-7[i] Enzyme families classified on the basis of amino acid structures (G. Jacoby and K. Bush,[ii] The sum of the subgroups in each family does not always equal to overall number of enzymes in each family due to withdrawn or non-classification of some enzymes.
17Epidemiology of ESBL-producing Enterobacteriaceae Stats of ESBL epidemiology are profoundly varied – all parts of the world have different rates of prevalence.In general terms;TEM-type ESBLs are predominantly reported in the United States,SHV-type ESBLs are most frequently isolated in Western Europe.CTX-M-type ESBLs have been detected in Australia, Latin America, Eastern Europe, and in specific countries such as Japan, Spain, & Kenya.Global epidemiology captures in major surveillance studies;AGAR (Australia)SENTRY (US, Canada & Latin America)SMART ( Global - US, SE Asia)EARSS (European countries)AGAR - Australian Group on Antimicrobial Resistance, SMART - Study for Monitor Antimicrobial Resistance Trends, EARSS - European Antibiotic Resistance Surveillance System (EARSS).
18Epidemiology of ESBL-producing Enterobacteriaceae contd… CountryStudy name or periodK. pneumoniaeE. coliNumber of isolatesPercentage of ESBL positiveCanadaSENTRY3864.912034.2US and CanadaSENTRY 1998192-USA20177.949663.3SENTRY 1997409447714.7Latin AmericaSENTRY25543.911425.41274023310.066447.312396.789745.420268.5Europe94622.638225.3Italy199920.046041.2SpainEARSS 200119621.55France612111.4GermanyPEG 20012688.26190.8Netherlands1997196<1571Turkey4348.85301.1Western Pacific area56024.61104Asian Pacific areaSENTRY67825.2133710.1China5595142723.6Taiwan200012411.317711.9Hong Kong19984721370211
19Detection of ESBLs in clinical isolates Use of both genotypic and phenotypic techniques.Phenotypic testing – a 2 steps process;Screening; screening process aims to exclude potential ESBL-producing isolates by testing for resistance or reduced susceptibility to 3GC cephalosporins .Screening using cefotaxime, cefpodoxime, ceftazidime, and aztreonam discs.multiple 3GC agents reliably improves sensitivity by offering wider ESBL substrate base.Confirmation; second step tests for synergy between 3GC cephalosporins & clavulanates (synergy between β-lactams and β-lactams-clavulanate combinations) – also known as DDST (double disc synergy test).A disc zone diameter difference of ≥5 mm between a cephalosporin and its respective cephalosporin- clavulanate is taken as a phenotypic confirmation of ESBL production.e.g an ESBL-producer tested against ceftazidime produces these resistance zones: ceftazidime zone = 16; ceftazidime-clavulanic acid zone = 21)Automated (Vitek 2 systems) MBDAutomated microbroth dilution - growth at or above screening concentrations (breakpoint) may indicate production of ESBL (that is, for E. coli and K. pneumoniae, MIC ≥ 2 μg/mL for ceftriaxone, ceftazidime, aztreonam, or cefpodoxime).E-test, microScan panels and other discs-based methods are also used.
20Detection of ESBLs in clinical isolates contd… Can you tell a plate depicting ESBL positive in the Figure above?
21Frequencies at assigned age categories Snapshots from ESBL study Summarized results of all isolates grouped by setting (hospital vs. community), ESBL-producer status, and by age categoriesSettingESBL positiveESBL negativeTotalHospital30259289community75402477105661766Frequencies at assigned age categories0-20 years old21-40 years old41-60 years old≥61 years old11261553ESBL positive: 10.4% (30/289) of isolates_HP, 15.7% (75/477) of isolates recovered from CP, > 1/2 (50.5% i.e. (53/105)) of all ESBL-positive isolates were isolated from patients aged 61 years and over. Within this sub-group, 75% of the patients were aged in their 70s.
22Snapshots from ESBL study contd… Comparison of percentage resistance of ESBL-producing isolates recovered from patients in hospital (HP) and community (CP) settings
23Preventing growing threats of ESBL-mediated antimicrobial resistance What should be done to curb increasing threats pose by ESBL- mediated antibiotic resistance;Robust antibiotic stewardship – appropriate use of antibioticsEffective infection control measures in hospitals – effective preventive measures to curb transmission;Contact precautions,Hand hygiene,Disinfections of inanimate objects, surfaces, medical devices in healthcare facilitiesPublic education – antibiotic resistance awareness campaign.Controlling use of antibiotics in food chains – control & regulation of antibiotic use in agriculture.Immunization – preventative & indirectDevelopment of newer, potent antibiotics against emerging multidrug resistant bacteria.Timely detection, and reporting of ESBL producing bacteria by medical laboratories.Instituting infection control measures in institutionalised care settings – eg nursing homes.Active screening for multi-drug resistant Enterobacteriaceae.Classifying ESBL-PE as notifiable infections???
24Treatment of infections caused by ESBL-producing Enterobacteriaceae. Therapeutic options are very limited.Treatment usually involves a combination of drugs.These are usually the expensive, last line of antibiotics;Carbapenems (e.g meropenem, ertapenem)Fosfomycin.β-lactam/β-lactam-inhibitor combination drugs (e.g Amoxicillin-clavulanate, piperacillin-tazobactam…etc) – supporting evidence from clinical studies is, however, controversial.Limitation of therapeutic drugs is also compounded by other factors such as;Site of infection,Severity of infection,Renal or liver functions of a patient,Age,Pregnancy or lactation status,Other medications the patient may be taking.