First report of the bla(OXA-58) gene in a clinical isolate of Acinetobacter baumannii in Rio de Janeiro, Brazil

Drug resistance phenotypes and genotypes in Mexico in representative gram-negative species: Results from the infivar network

Aim

This report presents phenotypic and genetic data on the prevalence and characteristics of extended-spectrum β-lactamases (ESBLs) and representative carbapenemases-producing Gram-negative species in Mexico.

Material and methods

A total of 52 centers participated, 43 hospital-based laboratories and 9 external laboratories. The distribution of antimicrobial resistance data for Escherichia coli, Klebsiella pneumoniae, Enterobacter cloacae complex, Acinetobacter baumannii complex, and Pseudomonas aeruginosa in selected clinical specimens from January 1 to March 31, 2020 was analyzed using the WHONET 5.6 platform. The following clinical isolates recovered from selected specimens were included: carbapenem-resistant Enterobacteriaceae, ESBL or carbapenem-resistant E. coli, and K. pneumoniae, carbapenem-resistant A. baumannii complex, and P. aeruginosa. Strains were genotyped to detect ESBL and/or carbapenemase-encoding genes.

Results

Among blood isolates, A. baumannii complex showed more than 68% resistance for all antibiotics tested, and among Enterobacteria, E. cloacae complex showed higher resistance to carbapenems. A. baumannii complex showed a higher resistance pattern for respiratory specimens, with only amikacin having a resistance lower than 70%. Among K. pneumoniae isolates, bla_TEM, bla_SHV, and bla_CTX were detected in 68.79%, 72.3%, and 91.9% of isolates, respectively. Among E. coli isolates, bla_TEM, bla_SHV, and bla_CTX were detected in 20.8%, 4.53%, and 85.7% isolates, respectively. For both species, the most frequent genotype was bla_CTX-M-15. Among Enterobacteriaceae, the most frequently detected carbapenemase-encoding gene was bla_NDM-1 (81.5%), followed by bla_OXA-232 (14.8%) and bla_oxa-181(7.4%), in A. baumannii was bla_OXA-24 (76%) and in P. aeruginosa, was bla_IMP (25.3%), followed by bla_GES and bla_VIM (13.1% each).

Conclusion

Our study reports that NDM-1 is the most frequent carbapenemase-encoding gene in Mexico in Enterobacteriaceae with the circulation of the oxacillinase genes 181 and 232. KPC, in contrast to other countries in Latin America and the USA, is a rare occurrence. Additionally, a high circulation of ESBL bla_CTX-M-15 exists in both E. coli and K. pneumoniae.

Genetic Characterization of Plasmid-Borne bla OXA-58 in Distinct Acinetobacter Species

Although the bla_OXA-58 gene has been infrequently described in Brazil, contrasting with other bordering South American countries, we verified the maintenance of this resistance determinant over time among carbapenem-resistant Acinetobacter species isolates, not only in nosocomial settings but also in the environment. In addition, to the best of our knowledge, this is the first study to have used WPS analysis to evaluate the genetic surroundings of bla_OXA-58 in Brazil. Moreover, the A. seifertii and A. baumannii clinical strains evaluated in this study were recovered 17 years apart in hospitals located in distinct Brazilian geographic regions.

We characterize by whole-plasmid-sequence (WPS) two-plasmid-borne bla_OXA-58 obtained from Acinetobacter seifertii (Asp-1069) and A. baumannii (Acb-45063) clinical strains recovered 17 years apart from distinct Brazilian regions. Multilocus sequence type (MLST) analysis showed that the Asp-1069 and Acb-45063 strains belong to ST551 and ST15/CC15, respectively. WPS analysis demonstrated that bla_OXA-58 was located in two distinct plasmids named pAs1069_a (24,672 bp/44 open reading frames [ORFs]) and pAb45063_b (19,808 bp/24 ORFs), which belong to the GR8/GR23 (repAci23) and GR4 (repAci4) incompatibility groups, respectively. The genetic environments surrounding bla_OXA-58 revealed that it was flanked by two intact ISAba3 copies on pAb45063_b, which differed from pAs1069_a. In the latter, the upstream ISAba3 copy was truncated by insertion of ISAba825 element. Although Re27-specific recombination sites were found adjacent to ISAba3-bla_OXA-58-ISAba3 arrangement on pAb45063_b, such structures were absent on pAs1069_a. The conserved ISAba125-araC1-lysE arrangement was disrupted by TnaphA6 harboring the aminoglycosides resistance gene aphA6 on pAs1069_a, while an IS26-bla_TEM-1-aac(3)-IIa-IS26 genetic structure was found upstream from ISAba3-bla_OXA-58-ISAba3 on pAb45063_b. Other two plasmids, pAb45063_a (183,767 bp/209 ORFs) and pAs1069_b (13,129 bp/14 ORFs), were also found in the OXA-58-producing Acinetobacter species strains, harboring the strA and strB genes and the sul2 gene, which confer resistance to streptomycin and sulfonamides, respectively. The plasmid-mediated virulence factors corresponding to genes tonB, spl, glmM, ppa, sulP, and map were found in both strains, as well distinct toxin-antitoxin system-encoding genes stbD and relE (pAs1069_a), brnT and brnA (pAb45063_b), and xreE (pAb45063_a). Although infrequently reported in Brazil, plasmid-borne bla_OXA-58 showed a complex and diverse genetic backbone that confers stability in different Acinetobacter species that have been isolated from nosocomial settings over time.

IMPORTANCE Although the bla_OXA-58 gene has been infrequently described in Brazil, contrasting with other bordering South American countries, we verified the maintenance of this resistance determinant over time among carbapenem-resistant Acinetobacter species isolates, not only in nosocomial settings but also in the environment. In addition, to the best of our knowledge, this is the first study to have used WPS analysis to evaluate the genetic surroundings of bla_OXA-58 in Brazil. Moreover, the A. seifertii and A. baumannii clinical strains evaluated in this study were recovered 17 years apart in hospitals located in distinct Brazilian geographic regions.

Molecular mechanisms of antimicrobial resistance in Acinetobacter baumannii, with a special focus on its epidemiology in Lebanon

Acinetobacter baumannii is an opportunistic bacterium involved in several types of infection with high mortality and morbidity, especially in intensive care units. Treatment of these infections remains a challenge due to the worldwide emergence of broad-spectrum resistance to many antibiotics. Following the implementation of molecular techniques to study A. baumannii outbreaks, it has been shown that they are mainly caused by specific clones such as international clones I, II and III. The present work aims to review the available data on the mechanisms underlying antimicrobial resistance in A. baumannii, with a special focus on the molecular epidemiology of this species in Lebanon.

The epidemiology of carbapenemases in Latin America and the Caribbean

INTRODUCTION

Enterobacteriaceae, Pseudomonas spp., and Acinetobacter spp. infections are major causes of morbidity and mortality, especially due to the emergence and spread of β-lactamases. Carbapenemases, which are β-lactamases with the capacity to hydrolyze or inactivate carbapenems, have become a serious concern as they have the largest hydrolytic spectrum and therefore limit the utility of most β-lactam antibiotics. Areas covered: Here, we present an update of the current status of carbapenemases in Latin America and the Caribbean. Expert commentary: The increased frequency of reports on carbapenemases in Latin America and the Caribbean shows that they have successfully spread and have even become endemic in some countries. Countries such as Brazil, Colombia, Argentina, and Mexico account for the majority of these reports. Early suspicion and detection along with implementation of antimicrobial stewardship programs in all healthcare settings are crucial for the control and prevention of carbapenemase-producing bacteria.

High prevalence of bla OXA-23 in Acinetobacter spp. and detection of bla NDM-1 in A. soli in Cuba: report from National Surveillance Program (2010-2012)

As a first national surveillance of Acinetobacter in Cuba, a total of 500 Acinetobacter spp. isolates recovered from 30 hospitals between 2010 and 2012 were studied. Acinetobacter baumannii–calcoaceticus complex accounted for 96.4% of all the Acinetobacter isolates, while other species were detected at low frequency (A. junii 1.6%, A. lwoffii 1%, A. haemolyticus 0.8%, A. soli 0.2%). Resistance rates of isolates were 34–61% to third-generation cephalosporins, 49–50% to β-lactams/inhibitor combinations, 42–47% to aminoglycosides, 42–44% to carbapenems and 55% to ciprofloxacin. However, resistance rates to colistin, doxycycline, tetracycline and rifampin were less than 5%. Among carbapenem-resistant isolates, 75% harboured different bla_OXA genes (OXA-23, 73%; OXA-24, 18%; OXA-58, 3%). The bla_NDM-1 gene was identified in an A. soli strain, of which the species was confirmed by sequence analysis of 16S rRNA gene, rpoB, rpoB–rpoC and rpoL–rpoB intergenic spacer regions and gyrB. The sequences of bla_NDM-1 and its surrounding genes were identical to those reported for plasmids of A. baumannii and A. lwoffi strains. This is the first report of bla_NDM-1 in A. soli, together with a high prevalence of OXA-23 carbapenemase for carbapenem resistance in Acinetobacter spp. in Cuba.

Carbapenem resistance in Pseudomonas aeruginosa and Acinetobacter baumannii in the nosocomial setting in Latin America

Increasing prevalence of carbapenem-resistant Pseudomonas aeruginosa and Acinetobacter baumannii strains in the nosocomial setting in Latin America represents an emerging challenge to public health, as the range of therapeutic agents active against these pathogens becomes increasingly constrained. We review published reports from 2002 to 2013, compiling data from throughout the region on prevalence, mechanisms of resistance and molecular epidemiology of carbapenem-resistant strains of P. aeruginosa and A. baumannii. We find rates of carbapenem resistance up to 66% for P. aeruginosa and as high as 90% for A. baumannii isolates across the different countries of Latin America, with the resistance rate of A. baumannii isolates greater than 50% in many countries. An outbreak of the SPM-1 carbapenemase is a chief cause of resistance in P. aeruginosa strains in Brazil. Elsewhere in Latin America, members of the VIM family are the most important carbapenemases among P. aeruginosa strains. Carbapenem resistance in A. baumannii in Latin America is predominantly due to the oxacillinases OXA-23, OXA-58 and (in Brazil) OXA-143. Susceptibility of P. aeruginosa and A. baumannii to colistin remains high, however, development of resistance has already been detected in some countries. Better epidemiological data are needed to design effective infection control interventions.