Acinetobacter baumannii IC2 and IC5 isolates with co-existing blaOXA-143-like and blaOXA-72 and exhibiting strong biofilm formation in a Mexican hospital

Acinetobacter baumannii is an opportunistic pathogen responsible for healthcare-associated infections (HAIs) and outbreaks. Antimicrobial resistance mechanisms and virulence factors allow it to survive and spread in the hospital environment. However, the molecular mechanisms of these traits and their association with international clones are frequently unknown in low- and middle-income countries. Here, we analyze the phenotype and genotype of seventy-six HAIs and outbreak-causing A. baumannii isolates from a Mexican hospital over ten years, with special attention to the carbapenem resistome and biofilm formation. The isolates belonged to the global international clone (IC) 2 and the Latin America endemic IC5 and were predominantly extensively drug-resistant (XDR). Oxacillinases were identified as a common source of carbapenem resistance. We noted the presence of the blaOXA-143-like family (not previously described in Mexico), the blaOXA-72 and the blaOXA-398 found in both ICs. A low prevalence of efflux pump overexpression activity associated with carbapenem resistance was observed. Finally, strong biofilm formation was found, and significant biofilm-related genes were identified, including bfmRS, csuA/BABCDE, pgaABCD and ompA. This study provides a comprehensive profile of the carbapenem resistome of A. baumannii isolates belonging to the same pulse type, along with their significant biofilm formation capacity. Furthermore, it contributes to a better understanding of their role in the recurrence of infection and the endemicity of these isolates in a Mexican hospital

Pandrug-resistant Acinetobacter baumannii from different clones and regions in Mexico have a similar plasmid carrying the blaOXA-72 gene

BackgroundMultidrug-resistant Acinetobacter baumannii is a common hospital-acquired pathogen. The increase in antibiotic resistance is commonly due to the acquisition of mobile genetic elements carrying antibiotic resistance genes. To comprehend this, we analyzed the resistome and virulome of Mexican A. baumannii multidrug-resistant isolates.MethodsSix clinical strains of A. baumannii from three Mexican hospitals were sequenced using the Illumina platform, the genomes were assembled with SPAdes and annotated with Prokka. Plasmid SPAdes and MobRecon were used to identify the potential plasmid sequences. Sequence Type (ST) assignation under the MLST Oxford scheme was performed using the PubMLST database. Homologous gene search for known virulent factors was performed using the virulence factor database VFDB and an in silico prediction of the resistome was conducted via the ResFinder databases.ResultsThe six strains studied belong to different STs and clonal complexes (CC): two strains were ST208 and one was ST369; these two STs belong to the same lineage CC92, which is part of the international clone (IC) 2. Another two strains were ST758 and one was ST1054, both STs belonging to the same lineage CC636, which is within IC5. The resistome analysis of the six strains identified between 7 to 14 antibiotic resistance genes to different families of drugs, including beta-lactams, aminoglycosides, fluoroquinolones and carbapenems. We detected between 1 to 4 plasmids per strain with sizes from 1,800 bp to 111,044 bp. Two strains from hospitals in Mexico City and Guadalajara had a plasmid each of 10,012 bp pAba78r and pAba79f, respectively, which contained the blaOXA-72 gene. The structure of this plasmid showed the same 13 genes in both strains, but 4 of them were inverted in one of the strains. Finally, the six strains contain 49 identical virulence genes related to immune response evasion, quorum-sensing, and secretion systems, among others.ConclusionResistance to carbapenems due to pAba78r and pAba79f plasmids in Aba pandrug-resistant strains from different geographic areas of Mexico and different clones was detected. Our results provide further evidence that plasmids are highly relevant for the horizontal transfer of antibiotic resistance genes between different clones of A. baumannii

Sulfhydryl variable-5 extended spectrum β-lactamase in nosocomial enteric bacteria causing sepsis in mexican children

Introduction: Enteric bacteria causing nosocomial infections are often resistant to third-generation cephalosporins due to the production of extended-spectrum β-lactamases (ESBLs). Objective: To describe and characterize the ESBLs pattern present in Klebsiella pneumoniae and Serratia marcescens strains, isolated as causative of nosocomial sepsis in pediatric patients at Instituto Nacional de Pediatría (National Institute of Pediatrics). Material and methods: We analyzed 94 strains of K. pneumoniae and 7 of S. marcescens isolated from clinical specimens from 2002-2005, causative of sepsis in a children’s hospital. We evaluated antibiotic susceptibility and detection of ESBL phenotypes by disk diffusion methods; ceftazidime-resistant isolates were further characterized by pulsed field gel electrophoresis (PFGE); and ESBLs were phenotypically and genotypically characterized by isoelectric focusing, polymerase chain reaction (PCR) and sequencing. We also assed for presence of conjugative plasmids bearing the ESBL gene. Results: 51/94 (54%) of K. pneumoniae isolates, and 5/7 (71%) of S. marcescens isolates were resistant to ceftazidime; all carried a blaSHV-5 gene. All K. pneumoniae isolates had a distinct PFGE profile, yet all carried a ~48-Kb plasmid, that was conjugatively transferable to an Escherichia coli receptor, which expressed the resistance phenotype. On the other hand, all S. marcescens isolates had a similar PFGE profile, were unable to transfer the ceftazidime-resistance phenotype, and were isolated from the same ward in a short time-span suggesting an outbreak. Conclusions: The overall prevalence of ESBL-producing enteric bacteria in this hospital is high but similar to other Latin American reports. The sulfhydryl variable-5 (SHV-5) ESBL gene appears to reside in a highly mobile plasmid, capable of spreading among different K. pneumoniae clones and perhaps even to S. marcescens

<i>Acinetobacter baumannii</i> IC2 and IC5 Isolates with Co-Existing <i>bla</i>_OXA-143-like and <i>bla</i>_OXA-72 and Exhibiting Strong Biofilm Formation in a Mexican Hospital

Acinetobacter baumannii is an opportunistic pathogen responsible for healthcare-associated infections (HAIs) and outbreaks. Antimicrobial resistance mechanisms and virulence factors allow it to survive and spread in the hospital environment. However, the molecular mechanisms of these traits and their association with international clones are frequently unknown in low- and middle-income countries. Here, we analyze the phenotype and genotype of seventy-six HAIs and outbreak-causing A. baumannii isolates from a Mexican hospital over ten years, with special attention to the carbapenem resistome and biofilm formation. The isolates belonged to the global international clone (IC) 2 and the Latin America endemic IC5 and were predominantly extensively drug-resistant (XDR). Oxacillinases were identified as a common source of carbapenem resistance. We noted the presence of the blaOXA-143-like family (not previously described in Mexico), the blaOXA-72 and the blaOXA-398 found in both ICs. A low prevalence of efflux pump overexpression activity associated with carbapenem resistance was observed. Finally, strong biofilm formation was found, and significant biofilm-related genes were identified, including bfmRS, csuA/BABCDE, pgaABCD and ompA. This study provides a comprehensive profile of the carbapenem resistome of A. baumannii isolates belonging to the same pulse type, along with their significant biofilm formation capacity. Furthermore, it contributes to a better understanding of their role in the recurrence of infection and the endemicity of these isolates in a Mexican hospital

Antibiotic susceptibility for 112 nosocomial isolates of <i>Acinetobacter baumannii</i>.

<p>Antibiotic susceptibility for 112 nosocomial isolates of <i>Acinetobacter baumannii</i>.</p

Frequency analysis of <i>A</i>. <i>baumannii</i> clones during 2014.

<p>(A) Frequency of each clone isolated by ward. (B) Frequency of each clone by month of isolation.</p

Analysis of serum resistance activity by <i>A</i>. <i>baumannii</i> clones.

<p>Each <i>A</i>. <i>baumannii</i> isolate was assessed by its ability to survive in normal human serum (NHS). (A) We show the percentage of <i>A</i>. <i>baumannii</i> isolates to survive in presence of 40% of NHS. (B) We show the ability of the members of each clone to survive at 40% of NHS. The dotted lines indicate the survival rate (0–25, 26–50, 51–75 and 76–100%) in presence of 40% of NHS. Open circle indicate patients that improved and every closed circle corresponded to a patient that died. Each point corresponds to the average of two independent experiments by duplicate. Each column indicates the SD.</p

Dendrogram constructed from PFGE patterns of one representative isolate for each <i>Acinetobacter baumannii</i> clone.

<p>Clone B contained most of the isolates.</p