P. aeruginosa was present in 75% of tested chronic wound samples, and the same clones persisted for more than 1 month. In addition, most bacteria contained virulence genes that were associated with high potential to establish infection. The use of silver in chronic wounds may be associated with multidrug resistance in P. aeruginosa; therefore, it is important to avoid colonization by these bacteria.
Carbapenem-resistance is a great challenge for antimicrobial therapy in Pseudomonas aeruginosa multidrug-resistant infections, as it reduces therapeutic options. This study investigated carbapenem-resistance mechanisms in six strains of non-carbapenemase-producing P. aeruginosa. Minimal inhibitory concentrations for imipenem and meropenem were determined by epsilometric test and broth microdilution. Mutations in the oprD gene were investigated by PCR, followed by sequencing. Transcriptional levels of oprD, ampC, and efflux pumps genes were analysed through RT-qPCR. Detection of efflux and AmpC activity was assessed by MIC reduction in the presence of the inhibitors: PAβN and cloxacillin, respectively. Resistant strains showed moderate levels of resistance for the evaluated carbapenems. Sequencing of oprD gene revealed similar mutation patterns in strains of the same Sequence Type -ST. A premature stop codon was detected only in the resistant strains of ST2236. Indel mutations were found in the oprD gene of ST2237 strains. Failure to detect oprD transcripts by RT-qPCR further confirms the absence of porin on ST2237 strains. ST2236 strains showed low transcriptional levels for oprD. MexXY-OprM was the only efflux system overexpressed in resistant strains. However, no efflux and AmpC activity was detected. High transcriptional levels of ampC were found in 50% of non-induced resistant strains. All imipem-induced resistant strains showed an increase in ampC expression (>102 - 103 X). It was concluded that the reduction and/or loss of OprD associated with AmpC overexpression is probably the main carbapenem-resistance mechanism in the evaluated strains.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.