Abstract
BackgroundBacteria that produce Klebsiella pneumoniae carbapenemases (KPCs) are resistant to broad-spectrum β-lactam antibiotics. The objective of this study was to phenotypically and genotypically characterize the antibiotic susceptibility to carbapenems of 297 isolates recovered from clinical samples obtained from inpatients at 16 hospitals in São Luis (Maranhão, Brazil).MethodsThe study was conducted using phenotypic tests and molecular methods, including polymerase chain reaction (PCR), sequencing and enterobacterial repetitive intergenic consensus (ERIC)-PCR. The nonparametric chi-square test of independence was used to evaluate the associations between the bacterial bla KPC gene and the modified Hodge test, and the chi-square adherence test was used to assess the frequency of carbapenemases and their association with the bla KPC gene.ResultsThe most frequently isolated species were Acinetobacter baumannii (n = 128; 43.0%), K. pneumoniae (n = 75; 25.2%), and Pseudomonas aeruginosa (n = 42; 14.1%). Susceptibility assays showed that polymixin B was active against 89.3% of the bacterial isolates. The Acinetobacter spp. and K. pneumoniae strains were susceptible to amikacin and tigecycline, and Pseudomonas spp. were sensitive to gentamicin and amikacin. Among the 297 isolates, 100 (33.7%) were positive for the bla KPC gene, including non-fermentative bacteria (A. baumannii) and Enterobacteriaceae species. Among the isolates positive for the bla KPC gene, K. pneumoniae isolates had the highest positivity rate of 60.0%. The bla KPC gene variants detected included KPC-2, which was found in all isolates belonging to species of the Enterobacteriaceae family. KPC-2 and KPC-3 were observed in A. baumannii isolates. Importantly, the bla KPC gene was also detected in three Raoultella isolates and one isolate of the Pantoea genus. ERIC-PCR patterns showed a high level of genetic diversity among the bacterial isolates; it was capable of distinguishing 34 clones among 100 strains that were positive for bla KPC and were circulating in 11 of the surveyed hospitals.ConclusionsThe high frequency of the bla KPC gene and the high degree of clonal diversity among microorganisms isolated from patients from different hospitals in São Luis suggest the need to improve the quality of health care to reduce the incidence of infections and the emergence of carbapenem resistance in these bacteria as well as other Gram-negative pathogens.
Highlights
Bacteria that produce Klebsiella pneumoniae carbapenemases (KPCs) are resistant to broad-spectrum β-lactam antibiotics
Klebsiella pneumoniae carbapenemases (KPCs) are βlactamases commonly produced by blaKPC geneharboring bacteria of the Enterobacteriaceae family, such as Klebsiella pneumoniae, Escherichia coli and Enterobacter spp. [1, 2]
This study showed the spread of multi-drug-resistant (MDR) bacterial strains isolated from clinical samples from patients in different healthcare facilities who showed resistance or decreased carbapenem antimicrobial susceptibility to imipenem, meropenem or ertapenem
Summary
Bacteria that produce Klebsiella pneumoniae carbapenemases (KPCs) are resistant to broad-spectrum β-lactam antibiotics. The dispersion of bacteria carrying the blaKPC gene in hospitals is a growing concern due to increased resistance to carbapenems, such as imipenem and meropenem, with significant increases observed in the minimum inhibitory concentrations (MICs) of these drugs for K. pneumoniae and other pathogens [8]. This dispersion appears to have increased globally, mainly in South America, with recent reports in Argentina and Brazil following the first report in Colombia in 2006 [9,10,11]. There is justifiable concern that new variants may arise, and horizontal transfer of the blaKPC gene has been detected in other bacterial species commonly found in the hospital environment [12]
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