Draft Genome Sequence of a Pseudomonas sp. Strain Carrying blaIMP-25 and blaVIM-2 Carbapenemase Genes from Hospital Sewage

Carbapenemase-producing Gram-negative bacteria in aquatic environments: a review

Antibiotic resistance is one of the greatest public-health challenges worldwide, especially with regard to Gram-negative bacteria (GNB). Carbapenems are the β-lactam antibiotics of choice with the broadest spectrum of activity and, in many cases, are the last-resort treatment for several bacterial infections. Carbapenemase-encoding genes, mainly carried by mobile genetic elements, are the main mechanism of resistance against carbapenems in GNB. These enzymes exhibit a versatile hydrolytic capacity and confer resistance to most β-lactam antibiotics. After being considered a clinical issue, increasing attention is being giving to the dissemination of such resistance mechanisms in the environment and especially through water. Aquatic environments are among the most significant microbial habitats on our planet, known as a favourable medium for antibiotic gene transfer, and they play a crucial role in the huge spread of drug resistance in the environment and the community. In this review, we present current knowledge regarding the spread of carbapenemase-producing isolates in different aquatic environments, which may help the implementation of control and prevention strategies against the spread of such dangerous resistant agents in the environment.

Microbial infection pattern, pathogenic features and resistance mechanism of carbapenem-resistant Gram negative bacilli during long-term hospitalization

BACKGROUND

Carbapenem-resistant Gram-negative bacilli (GNB) have become an important cause of nosocomial infections of hospitalized patients.

METHODS

To investigate the microbial infection patterns and molecular epidemiology characteristics of the carbapenem-resistant GNB isolates from a long-term hospitalized patient, antimicrobial susceptibility testing, phenotypic screening test for carbapenemase production, PCR screening and DNA sequencing of carbapenemase genes, repetitive extragenic palindromic sequence-based PCR (REP-PCR), multilocus sequencing typing (MLST) and genetic environment analysis were performed.

RESULTS

Twelve strains with carbapenemase genes were detected from 63 carbapenem-resistant isolates, including two bla_IMP-25-carrying Pseudomonas aeruginosa, one bla_NDM-1-carrying Citrobacter freundii, three bla_NDM-1-carrying Klebsiella pneumoniae and six bla_KPC-2-carrying K. pneumoniae. Only the bla_NDM-1 genes were successfully transferred from three K. pneumoniae strains to Escherichia coli C600 by conjugation. Genetic environment of bla_IMP-25, bla_NDM-1 and bla_KPC-2 genes in our study were consistent with previous reports. Molecular typing of K. pneumoniae performed by MLST revealed that most of the isolates belonged to ST11. bla_NDM-1-carrying K. pneumoniae sequencing type 1416 was first reported in our study.

CONCLUSIONS

Carbapenem-resistant GNB are common pathogens during long-term hospitalization, and ST11 bla_KPC-2-carrying K. pneumoniae is the dominant bacterium in our study. Colonization and horizontal transmission of resistance by plasmids of carbapenem-resistant GNB have increased the risks of persistent infection and mortality of long-term hospitalized patients.