MULTIDRUG-RESISTANT GRAM NEGATIVE NONFERMENTATIVE BACTERIA Sanda Sardelić, MD, PhD CHC Split, Croatia ESCMID Course, Primošten, Croatia, September 28-30, 2011
MDR nonfermentative bacteria Opportunistic Gram-negative pathogens with increasing relevance in a variety of hospitalacquired infections especially among intensive care unit patients Agents with persistence in healthcare facilities Easy dissemination of clonal outbreak strains Use of off-label combinations to treat infections
MDR nonfermentative bacteria of major concern in hospital setting Pseudomonas aeruginosa Pseudomonas aeruginosa Acinetobacter baumannii Stenotrophomonas maltophilia, Burkholderia cepacia, Elisabethkingia meningoseptica, Chryseobacterium indologenes, Pseudomonas putida, Sphingomonas paucimobilis, Achromobacter xylosooxydans
Hospital sources of nonfermentative Patients Hands of staff Ventilators Humidifiers Oxygen analysers Respirometers Bronchoscopes Bed frames Rubbish bins Sinks GNB Air supply Jugs Bowls Soap Hand cream Lotion dispensers Plastic screens Bed linen Service ducts /dust Bedside charts
Identification of NFGNB Difficulties: Many species infrequent Many grow slowly Biochemical activity weak Taxonomic changes frequent Commercial systems of low accuracy Possibilities: VITEK 2 ID GNB (95% accuracy) In comparison with 16S approx. 60% to species/genus level API 20NE 16S, 23S rrna PCR of housekeeping genes (rpob, gyrb, reca) Systems using bacterial mass spectrum databases
Susceptibility testing: EUCAST Breakpoints exist for P. aeruginosa, A. baumannii, Stenotrophomonas maltophilia (SXT) FAQ, www.eucast.org 16. Which breakpoints should we could use for nonfermenting Gram-negative rods other than Pseudomonas spp. and Acinetobacter spp? Breakpoints for groups of organisms currently without specific breakpoints are being examined and in the meantime for practical purposes application of the non-species related breakpoints is recommended. /2011-02-28 non-species related breakpoints
Multidrug resistance in P. aeruginosa - definitions Agents active: antipseudomonal penicillins+bli (piperacillin-tazobactam, ticarcillin+clavulanic acid), antipseudomonal cephalosporins (ceftazidime, cefepime), fluoroquinolons (ciprofloxacin, levofloxacin), aminoglycosides (gentamicin, tobramycin, amikacin, netilmicin), antipseudomonal carbapenems (imipenem, meropenem, doripenem), polymyxins (colistin, polymyxin B), monobactams (aztreonam), phosphonic acid (fosfomycin) Criteria for defining MDR, XDR and PDR in Pseudomonas aeruginosa MDR: non-susceptible to 1 agent in 3 antimicrobial categories XDR: non-susceptible to 1 agent in all but 2 categories, PDR: non-susceptible to all antimicrobial agents listed
Multidrug resistance in A. baumannii - definitions Agents active: antipseudomonal penicillins+bli (piperacillin-tazobactam, ticarcillin+clavulanic acid), extended spectrum cephalosporins (cefotaxime, ceftriaxone, ceftazidime, cefepime), ampicillin/sulbactam, fluoroquinolons (ciprofloxacin, levofloxacin), aminoglycosides (gentamicin, tobramycin, amikacin, netilmicin), antipseudomonal carbapenems (imipenem, meropenem, doripenem), polymyxins (colistin, polymyxin B), trimethoprim-sulfamethoxazole, tetracyclines (tetracycline, doxycycline, minocycline) Criteria for defining MDR, XDR and PDR in Acinetobacter spp. MDR: non-susceptible to 1 agent in 3 antimicrobial categories XDR: non-susceptible to 1 agent in all but 2 categories, PDR: non-susceptible to all antimicrobial agents listed
MDR Pseudomonas aeruginosa
Intrinsic resistance in P. aeruginosa: inheritable, stable, not dependent on environment Main mechanism: outer membrane acts as a selective barrier to uptake of antibiotics β-lactamase production (AmpC) Efflux pumps
Acquired resistance Horizontal transfer β-lactamases, aminoglygoside modifying genes Mutational resistance reduced uptake, enhanced efflux, derepressed AmpC
Adaptive resistance inducible, dependent on continuous presence of environmental stimulus Enviromental stimulus: antibiotics, biocides, polyamines, ph, anaerobiosis, cations, biofilm formation, swarming motility Possible because of large number of regulatory genes (9% of all) BIOFILM
Resistance to β-lactams Two endogenous chromosomal β-lactamases: Amp C (Class C) and PoxB (Class D) AmpC is inducible by number of β-lactams (amoxycillin, clavulanic acid, narrow-spectrum CS, carbapenems) Non-inducers: aztreonam, 3rd gen. CS Mutation leads to derepression: 3rd gen. CS hydrolyzed ES Amp C (Rodrigez-Martinez AAC, 2009): 3rd and 4th gen. CS, carbapenems.
ESBL Class A Resistance to β-lactams - aquired BL TEM, SHV NonTEM, nonshv: VEB, PER, GES, BEL, CTX-M, novel: PME (Tian GB et al. AAC 2011), KPC ESBL Class D OXA-2 and OXA-10 deriv., OXA-18, OXA-45 (clav.ac.inhib) carbapenemases DDST boronic acid inhibition of AmpC J Microbiol Methods 2011;87(1):116-8.
Carbapenemases Class A (ES with carbapenemase activity): GES-2 and GES-5; KPC-2 and KPC-5 (Colombia, Puerto Rico) Class B: IMP; VIM; GIM; SPM; AIM-1; NDM-1(Serbia: Jovcic B et al. AAC 2011;55:3929-31) GES-2
Susceptibility patterns of P. aeruginosa producing different β-lactamases
Laboratory detection of carbapenemases phenotypic methods MBL KPC OXA? Something else?
Resistance to fluoroquinolones Mutation of the target site: gyrase and topoisomerase IV Mutations leading to hyperexpression of efflux pumps
Antibiotics and mutationally overexpressed efflux pumps in P. aeruginosa (Livermore, CID 2003) Pump Mutation PIP CAZ/ FEP IPM MEM FQ AG ATM MexAB mexr r/r r/r r/r S r r/r S MexCD nfxb r/r r/r r/r S r r/r S MexEF mext r/r r/r r/r R r r/r S MexXY mezt r/r r/r r/r S r r/r r/r
In80 Resistance to aminoglycosides AG modifying enzymes all classes Most frequent acetyltransferase: Position 3-aminogroup: AAC-3 family gentamicin R Position 6 -aminogroup: AAC-6 family amikacin R Efflux: MexXY In493 (Italy) (Croatia)
Novel mechanisms of AG resistance 16S rrna methylase: pan-aminoglycoside resistance RmtA-RmtD, ArmA, NpmA
Resistance to polymyxines Lipid A is modified by addition of aminoarabinose A: untreated cell; B: cell treated with polymyxin C: cell treated with colistin methanesulfate; D: cell treated with polymyxin B at higher magnification The ability to produce lipid A is lost (AAC 2010;54:4971-7) CID 2005;40:1333-1341
Intrinsic resistance to polymyxines GNNFB: Elisabethkingia meningoseptica Chryseobacterium indologenes Burkholderia cepacia some strains Stenotrophomonas maltophilia (and Proteus Providencia Serratia ) C. indologenes
Genotyping methods MLST, PFGE, AFLP, MVLA MLST scheme: currently 972 STs http://pubmlst.org/paeruginosa/ eburst scheme: http://eburst.mlst.net Giske et al., 2006: European O12 MBL are ST229 (BG4) ST 235: AT, BE, FR, DE, HU, IT PL, RU, SR, SE, TU
Pseudomonas aeruginosa population structure
MDR Acinetobacter baumannii
Major infections due to Acinetobacter Ventilator-associated pneumonia Urinary tract Bloodstream infection Secondary meningitis Skin/wound infections Endocarditis CAPD-associated peritonitis Ventriculitis
Natural habitat of A. baumannii Yet to be determined Carrier rate is low Not typical environmental organism
Something so special about Acinetobacter baumannii Strain AYE ABaR1 Largest resistance island identified to date Contains 88 predicted ORFs, with 45 identified resistance genes (including 19 putative resistance genes not previously described in Acinetobacter) and 22 ORFs encoding transposases or mobility associated proteins (? 39 ORFs from Pseudomonas spp., 30 from Salmonella spp., 15 from E. coli) PLoS Genet 2(1): e7
Nonenzymatic mechanisms/ impact on resistance Outer membrane proteins (OMP)/ still investigational, maybe important Efflux AdeABC/ weak Altered penicillinbinding-proteins/ rare CarO (29 kd) - Carbapenems R (Limansky et al, 2002) 47, 44, 37 kd - Carbapenems R (Quale et al, 2003) 33-36 kd - Carbapenems R (del Mar Tomas et al, 2005) 22, 33 kd (with OXA-24 Bou et al, 2000 ) 43 kd (homology to OprD in P. aeruginosa, Dupont et al, 2005) HMP-AB (as OMP F in P. aeruginosa, Gribun et al, 2003)
Efflux pumps described in A. baumannii Efflux pump /Family/ Tet(A) /MFS/ Tet(B) /MFS/ CmlA /MFS/ AdeABC, AdeIJK, AdeFGH /RND/ AbeM /MATE/ Family Antibiotics tetracyclines tetracyclines, minocycline chloramphenicol aminoglycosides, β-lactams (including carbapenems), chloramphenicol, erythromycin, tetracyclines and ethidium bromide; reduced susceptibility to fluoroquinolones norfloxacin, ofloxacin, ciprofloxacin, gentamicin (Vila J et al. J Antimicrob Chemother 2007;59:1210-15, Espinal P et al. Fut Microbiol 2011:6:495-511)
Enzymatic mechanisms: β-lactamases with ES in A. baumannii Ambler class C - Amp C; ADC (ISAba1) Ambler class A - ESBL: PER, VEB, CTX- M, KPC (Puerto Rico, Mexico) Ambler class B - MBL: VIM, IMP, SIM, NDM Ambler class D - OXA
ES β-lactamases: genetic background AmpC derepressed: FEP and CP susc. ESBL: VEB-1: CP susc.
Class D carbapenemases: Carbapenem-Hydrolysing class D β- Lactamases (CHDL) Hydolyse carbapenems at a low level Do not hydolyse ES CS Not inhibited by clavulanic acid > 150 enzymes: OXA-23 group, OXA-24/40 group, OXA-58 group, OXA- 143 group, (oxa-51 group intrinsic) Variation in distribution: blaoxa-58-like Greece, Italy, blaoxa-40-like Spain, Portugal blaoxa-23-like North Europe, Asia, South America Woodford N et al. Fems Microbiol Rev 2011:35:736-55.
Laboratory detection of CHDL Performing MICs with 200 mm NaCl: not recommended (Zander et al. ECCMID, 2011)
Genotyping methods MLST scheme: http://pubmlst.org/abaumannii/ PFGE AFLP sequence-based typing scheme (ompa, OXA-51-like, csue) European clone (CC1-3): I (ST 1, 7, 8, 19, 20), II (ST 2, 45, 47), and III (ST 3, 14) Most outbreak strains belonged to ECI and II Woodford N et al. FEMS Microbiol Rev 2011;35:1736-55 Diancourt L et al. PlosONE 2010;5:e10034.
The population structure of A.b. Atypically homogenous compared to other nosocomial pathogens Relative recent reduction in population size the bottleneck (narrow ecological niche) Limited number of genotypic clusters of MDR strains spreading among hospitals Diancourt, PlosONE 2010;5(4)