title: Beta-lactam and aminoglycoside resistance rates and mechanisms among Pseudomonas aeruginosa in French general practice (community and private healthcare centres).
abstract: OBJECTIVE
  The aim of this study was to assess antibiotic resistance rates and mechanisms of beta-lactam and aminoglycoside resistance among isolates of Pseudomonas aeruginosa isolated in the extra-hospital setting (community and private healthcare centres).
  
  
  METHODS
  During a 4 month period, 226 non-repetitive strains of P. aeruginosa were collected from patients residing in private healthcare centres (73.5%) or at home (26.5%). Resistance rates were evaluated by MIC determination, and beta-lactam and aminoglycoside resistance was analysed by phenotypic tests, PCR amplification, cloning and sequencing.
  
  
  RESULTS
  Among the ticarcillin-resistant strains (38.1%), 33.7% overexpressed their chromosomal cephalosporinase, 27.9% produced acquired penicillinases (21 PSE-1, 2 OXA-21 and 1 TEM-2), 4.7% produced extended-spectrum beta-lactamases (ESBLs) (3 TEM-21 and 1 SHV-2a) and 45.3% possessed a non-enzymatic resistance (NER). Thus, 88.4% had a single mechanism of resistance, whereas 11.6% cumulated several mechanisms. No carbapenemases were detected among the 6.6% imipenem-resistant strains. With regard to aminoglycosides, 23.0% of the strains exhibited an acquired resistance to gentamicin (GEN), tobramycin (TOB), amikacin (AMK) or netilmicin (NET). Enzymatic resistance was more frequent (71.2%) than NER (34.6%). Various aminoglycoside modifying enzymes were associated with overlapping phenotypes: 36.5% strains produced AAC(6')-I with either a serine (GEN-TOB-NET) or a leucine (TOB-NET-AMK) at position 119, or both variants (GEN-TOB-NET-AMK); 21.2% expressed ANT(2'')-I (GEN-TOB), 7.7% AAC(3)-II (GEN-TOB-NET), 5.8% AAC(3)-I (GEN) and 1.9% AAC(6')-II (GEN-TOB-NET-AMK) or AACA7 (TOB-NET-AMK).
  
  
  CONCLUSIONS
  Antibiotic resistance rates in P. aeruginosa were globally similar in general practice as in French hospitals. This first analysis of resistance mechanisms showed an unexpectedly high frequency of ESBLs and an unusual distribution of aminoglycoside modifying enzymes.
authors.affiliation: UMR 5234, CNRS, Université de Bordeaux 2, 146 rue Léo Saignat, 33076 Bordeaux, France. veronique.dubois@bacterio.u-bordeaux2.fr
authors.forename: Véronique
authors.initials: V
authors.lastname: Dubois
authors.forename: Corinne
authors.initials: C
authors.lastname: Arpin
authors.forename: Virginie
authors.initials: V
authors.lastname: Dupart
authors.forename: Aline
authors.initials: A
authors.lastname: Scavelli
authors.forename: Laure
authors.initials: L
authors.lastname: Coulange
authors.forename: Catherine
authors.initials: C
authors.lastname: André
authors.forename: Isabelle
authors.initials: I
authors.lastname: Fischer
authors.forename: Frédéric
authors.initials: F
authors.lastname: Grobost
authors.forename: Jean-Philippe
authors.initials: JP
authors.lastname: Brochet
authors.forename: Isabelle
authors.initials: I
authors.lastname: Lagrange
authors.forename: Brigitte
authors.initials: B
authors.lastname: Dutilh
authors.forename: Jacqueline
authors.initials: J
authors.lastname: Jullin
authors.forename: Patrick
authors.initials: P
authors.lastname: Noury
authors.forename: Gilberte
authors.initials: G
authors.lastname: Larribet
authors.forename: Claudine
authors.initials: C
authors.lastname: Quentin
mesh_terms: D000123:Acetyltransferases / Q000096:biosynthesis; D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000617:Aminoglycosides / Q000494:pharmacology*; D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D001426:Bacterial Proteins / Q000235:genetics; D002648:Child; D002675:Child, Preschool; D003151:Community Health Centers; D017714:Community-Acquired Infections / Q000382:microbiology*; D004269:DNA, Bacterial / Q000737:chemistry / Q000235:genetics; D024881:Drug Resistance, Bacterial; D005260:Female; D005602:France; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D008297:Male; D008826:Microbial Sensitivity Tests; D008875:Middle Aged; D009713:Nucleotidyltransferases / Q000096:biosynthesis; D016133:Polymerase Chain Reaction; D011552:Pseudomonas Infections / Q000382:microbiology*; D011550:Pseudomonas aeruginosa / Q000187:drug effects* / Q000302:isolation & purification; D017422:Sequence Analysis, DNA; D001618:beta-Lactamases / Q000096:biosynthesis; D047090:beta-Lactams / Q000494:pharmacology*
chemical_list: D000617:Aminoglycosides; D000900:Anti-Bacterial Agents; D001426:Bacterial Proteins; D004269:DNA, Bacterial; D047090:beta-Lactams; D000123:Acetyltransferases; C019681:aminoglycoside acetyltransferase; D009713:Nucleotidyltransferases; C061037:aminoglycoside 6-adenylyltransferase; D001618:beta-Lactamases