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Polymorphism in ftsI gene and ß-lactam susceptibility in Portuguese Haemophilus influenzae strains: clonal dissemination of β-lactamase-positive isolates with decreased susceptibility to amoxicillin-clavulanic acid

2011-01-25Journal article Open access
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dc.contributor.authorBarbosa, Ana Raquel
dc.contributor.authorGiufrè, Maria
dc.contributor.authorCerquetti, Marina
dc.contributor.authorBajanca-Lavado, Maria Paula
dc.date.accessioned2011-12-05T15:43:41Z
dc.date.available2011-12-05T15:43:41Z
dc.date.issued2011-01-25
dc.description.abstractOBJECTIVES: The aim of this study was to characterize ampicillin resistance mechanisms in clinical isolates of Haemophilus influenzae from Portugal. Association between specific patterns of amino acid substitutions in penicillin-binding protein 3 (PBP3) (with or without β-lactamase production) and β-lactam susceptibility as well as genetic relatedness among isolates were investigated. METHODS: Two-hundred and forty non-consecutive H. influenzae isolates chosen according to their different ampicillin MICs [101 β-lactamase-non-producing ampicillin-resistant (BLNAR) isolates, 80 β-lactamase-producing ampicillin-resistant (BLPAR) isolates and 59 β-lactamase-non-producing ampicillin-susceptible (BLNAS) isolates] were analysed. The β-lactamase-encoding bla(TEM-1) gene was detected by PCR. The ftsI gene encoding PBP3 was sequenced. Genetic relatedness among isolates was examined by PFGE. RESULTS: Of the 240 H. influenzae isolates, 141 had mutations in the transpeptidase domain of the ftsI gene, including most BLNAR strains (94/101, 93.1%) and a high percentage of BLPAR strains (47/80, 58.8%). As previously reported, the latter have been described as β-lactamase-positive amoxicillin/clavulanic acid resistant (BLPACR). The most common amino acid substitutions were identified near the KTG motif: N526K (136/141, 96.5%), V547I (124/141, 87.9%) and N569S (121/141, 85.8%). The 141 strains were divided into 31 ftsI mutation patterns and included six groups (I, IIa, IIb, IIc, IId and III-like). BLNAR strains were genetically diverse but close genetic relationships were demonstrated among BLPACR strains. CONCLUSIONS: This study shows that the non-enzymatic mechanism of resistance to β-lactams is widespread among H. influenzae isolates in Portugal. Clonal dissemination of BLPACR strains showing high resistance to ampicillin and reduced susceptibility to amoxicillin/clavulanic acid was documented.por
dc.identifier.citationJ Antimicrob Chemother. 2011 Apr;66(4):788-96. Epub 2011 Jan 25por
dc.identifier.issn0305-7453
dc.identifier.otherdoi:10.1093/jac/dkq533
dc.identifier.urihttp://hdl.handle.net/10400.18/340
dc.language.isoengpor
dc.peerreviewedyespor
dc.publisherOxford University Presspor
dc.relation.publisherversionhttp://jac.oxfordjournals.org/cgi/pmidlookup?view=long&pmid=21393206por
dc.subjectInfecções Respiratóriaspor
dc.subjectHaemophilus influenzaepor
dc.subjectPenicillin binding proteinspor
dc.subjectAmpicillin resistancepor
dc.subjectGenetic relatednesspor
dc.subjectBLNARpor
dc.subjectBLPACRpor
dc.titlePolymorphism in ftsI gene and ß-lactam susceptibility in Portuguese Haemophilus influenzae strains: clonal dissemination of β-lactamase-positive isolates with decreased susceptibility to amoxicillin-clavulanic acidpor
dc.typejournal article
dspace.entity.typePublication
oaire.citation.endPage796por
oaire.citation.startPage788por
oaire.citation.titleJournal of Antimicrobial Chemotherapypor
rcaap.rightsopenAccesspor
rcaap.typearticlepor

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