Investigation of carbapenemases and aminoglycoside modifying enzymes of Acinetobacter baumannii isolates recovered from patients admitted to intensive care units in a tertiary-care hospital in Brazil

Abstract INTRODUCTION: Acinetobacter baumannii are opportunistic bacteria, highly capable of acquiring antimicrobial resistance through the production of carbapenemases and aminoglycoside modifying enzymes (AMEs). METHODS: Carbapenemase and AME genes were investigated in A. baumannii recovered from inpatients of a Brazilian hospital. RESULTS: The key genes found were bla OXA-51-like, the association ISAba1- bla OXA-23-like, and the AME genes aph(3´)-VI, aac(6´)-Ib, aac(3)-Ia, and aph(3´)-Ia. Different clusters spread through the institution wards. CONCLUSIONS: The dissemination of bla OXA-23-like and AME-carrying A. baumannii through the hospital highlights the need for improved preventive measures to reduce the spread of infection.

Investigation of carbapenemases and aminoglycoside modifying enzymes of Acinetobacter baumannii isolates recovered from patients admitted to intensive care units in a tertiary-care hospital in Brazil.

INTRODUCTION: Acinetobacter baumannii are opportunistic bacteria, highly capable of acquiring antimicrobial resistance through the production of carbapenemases and aminoglycoside modifying enzymes (AMEs). METHODS: Carbapenemase and AME genes were investigated in A. baumannii recovered from inpatients of a Brazilian hospital. RESULTS: The key genes found were bla OXA-51-like, the association ISAba1- bla OXA-23-like, and the AME genes aph(3´)-VI, aac(6´)-Ib, aac(3)-Ia, and aph(3´)-Ia. Different clusters spread through the institution wards. CONCLUSIONS: The dissemination of bla OXA-23-like and AME-carrying A. baumannii through the hospital highlights the need for improved preventive measures to reduce the spread of infection.

Endemicity of the High-Risk Clone Klebsiella pneumoniae ST340 Coproducing QnrB, CTX-M-15, and KPC-2 in a Brazilian Hospital.

The dissemination of multiresistant Klebsiella pneumoniae carbapenemase (KPC)-2-producing Klebsiella pneumoniae isolates belonging to international high-risk clones poses a major health care threat. In this study, 48 nonduplicated, carbapenem-resistant K. pneumoniae isolated from 2011 to 2014 in a tertiary hospital were investigated. The blaKPC-2 gene was the only determinant for carbapenem resistance. The blaCTX-M-15 gene was the main determinant for the production of extended-spectrum beta-lactamase (ESBL), whereas aph(3')-Ia and qnrB were the most common genes associated with resistance to aminoglycosides and quinolones, respectively. Nine different sequence types (STs) were identified. The most common was ST340. Molecular typing by enterobacterial repetitive intergenic consensus-PCR placed 48 strains among 10 different clusters. In the studied hospital, the high-risk clone of KPC-2-producing K. pneumoniae ST340, harboring genes that codify aminoglycoside modifying enzymes, QnrB and CTX-M-15 plus CTXM-2-type ESBLs, is disseminated and acts as a major agent of infections in critically ill patients.

Detection of P. aeruginosa harboring bla CTX-M-2, bla GES-1 and bla GES-5, bla IMP-1 and bla SPM-1 causing infections in Brazilian tertiary-care hospital.

BACKGROUND: Nosocomial infections caused by Pseudomonas aeruginosa presenting resistance to beta-lactam drugs are one of the most challenging targets for antimicrobial therapy, leading to substantial increase in mortality rates in hospitals worldwide. In this context, P. aeruginosa harboring acquired mechanisms of resistance, such as production of metallo-beta-lactamase (MBLs) and extended-spectrum beta-lactamases (ESBLs) have the highest clinical impact. Hence, this study was designed to investigate the presence of genes codifying for MBLs and ESBLs among carbapenem resistant P. aeruginosa isolated in a Brazilian 720-bed teaching tertiary care hospital. METHODS: Fifty-six carbapenem-resistant P. aeruginosa strains were evaluated for the presence of MBL and ESBL genes. Strains presenting MBL and/or ESBL genes were submitted to pulsed-field gel electrophoresis for genetic similarity evaluation. RESULTS: Despite the carbapenem resistance, genes for MBLs (blaSPM-1 or blaIMP-1) were detected in only 26.7% of isolates. Genes encoding ESBLs were detected in 23.2% of isolates. The blaCTX-M-2 was the most prevalent ESBL gene (19.6%), followed by blaGES-1 and blaGES-5 detected in one isolate each. In all isolates presenting MBL phenotype by double-disc synergy test (DDST), the blaSPM-1 or blaIMP-1 genes were detected. In addition, blaIMP-1 was also detected in three isolates which did not display any MBL phenotype. These isolates also presented the blaCTX-M-2 gene. The co-existence of blaCTX-M-2 with blaIMP-1 is presently reported for the first time, as like as co-existence of blaGES-1 with blaIMP-1. CONCLUSIONS: In this study MBLs production was not the major mechanism of resistance to carbapenems, suggesting the occurrence of multidrug efflux pumps, reduction in porin channels and production of other beta-lactamases. The detection of blaCTX-M-2,blaGES-1 and blaGES-5 reflects the recent emergence of ESBLs among antimicrobial resistant P. aeruginosa and the extraordinary ability presented by this pathogen to acquire multiple resistance mechanisms. These findings raise the concern about the future of antimicrobial therapy and the capability of clinical laboratories to detect resistant strains, since simultaneous production of MBLs and ESBLs is known to promote further complexity in phenotypic detection. Occurrence of intra-hospital clonal dissemination enhances the necessity of better observance of infection control practices.

A PCR-based strategy for Dombrock screening in Brazilian blood donors reveals a novel allele: the DO* A-WL.

BACKGROUND: Determination of the molecular basis underlying the antigens in the Dombrock blood group system has shown various rearrangements between the alleles associated with DO(*) A and DO(*) B. Based on this, we employed a PCR-based strategy to screen DO alleles (DO(*) A, DO(*) B, HY(*) 1, HY(*) 2 and JO) in Brazilians. METHODS: We tested DNA of 278 Brazilian blood donors by PCR-RFLP on plates of 96 wells to determine the 793A/G (DO(*) A/DO(*) B), 323G/T (HY), 350C/T (JO) and 898C/G (HY(*) 1/HY(*) 2) single nucletide polymorphisms. In order to confirm the results sequence analysis was also performed. RESULTS: When samples of these donors were analyzed, a novel allele combination, the DO(*) A allele (793A and 323G) associated with 898G was identified and designated as DO(*) A-WL allele. This new allele encoding 300Val is the same as HY(*) 1 at nucleotide 898 on the molecular background of DO(*) A. Among the 556 alleles analyzed by PCR-RFLP, 3 were DO(*) A-WL and 78 were DO(*) B-WL. This represents an overall frequency of 0.5% for DO(*) A-WL and 14% for DO(*) B-WL across the population studied. CONCLUSION: Molecular screening of Brazilians revealed one novel allele, the DO(*) A-WL. Our data highlight the importance of testing a cohort of different populations to determine DO haplotypes and to establish reliable genotyping tests for predicting Do(a)/Do(b) status.

High prevalence of bla(CTX-M) extended spectrum beta-lactamase genes in Klebsiella pneumoniae isolates from a tertiary care hospital: first report of bla(SHV-12), bla(SHV-31), bla(SHV-38), and bla(CTX-M-15) in Brazil.

The aim of this study was to investigate the presence and prevalence of bla(TEM), bla(SHV), and bla(CTX-M) and bla(GES)-like genes, responsible for extended spectrum beta-lactamases (ESBLs) production in clinical isolates of Klebsiella pneumoniae collected from a Brazilian tertiary care hospital. Sixty-five ESBL producing K. pneumoniae isolates, collected between 2005 and 2007, were screened by polymerase chain reaction (PCR). Identification of bla genes was achieved by sequencing. Genotyping of ESBL producing K. pneumoniae was performed by the enterobacterial repetitive intergenic consensus-PCR with cluster analysis by the Dice coefficient. The presence of genes encoding ESBLs was confirmed in 59/65 (90.8%) isolates, comprising 20 bla(CTX-M-2), 14 bla(CTX-M-59), 12 bla(CTX-M-15), 9 bla(SHV-12), 1 bla(SHV-2), 1 bla(SHV-2a), 1 bla(SHV-5), and 1 bla(SHV-31) genes. The ESBL genes bla(SHV-12), bla(SHV-31), and bla(CTX-M-15), and the chromosome-encoded SHV-type beta-lactamase capable of hydrolyzing imipenem were detected in Brazil for the first time. The analysis of the enterobacterial repetitive intergenic consensus-PCR band patterns revealed a high rate of multiclonal bla(CTX-M) carrying K. pneumoniae isolates (70.8%), suggesting that dissemination of encoding plasmids is likely to be the major cause of the high prevalence of these genes among the K. pneumoniae isolates considered in this study.