Genetic Background of β-Lactamases in Enterobacteriaceae Isolates from Environmental Samples

Abstract

The prevalence of β-lactamase-producing Enterobacteriaceae has increased worldwide. Although antibiotic-resistant bacteria are usually associated with hospitals, there are a growing number of reports of resistant bacteria in other environments. Concern about resistant microorganisms outside the hospital setting highlights the need to investigate mechanisms of antibiotic resistance in isolates collected from the environment. The present study evaluated the resistance mechanism to β-lactam antibiotics in 40 isolates from hospital sewage and surface water from the Dilúvio Stream, Porto Alegre City, Southern Brazil. The multiplex PCR technique was used to detect several resistance genes of β-lactamases: extended-spectrum β-lactamases (ESBLs), carbapenemases, and β-lactamase AmpC. After genes, detection amplicons were sequenced to confirm their identification. The clonal relationship was established by DNA macrorestriction using the XbaI enzyme, followed by pulsed-field gel electrophoresis (PFGE). The results indicated that resistance genes were present in 85% of the isolates. The most prevalent genes encoded narrow-spectrum β-lactamase, such as TEM-1 and SHV-1 with 70% of the strains, followed by carbapenemase KPC and GES (45%), ESBL types SHV-5 and CTX-M-8 (27.5%), and AmpC (ACT-1/MIR-1) (2.5%). Twelve isolates contained only one resistance gene, 14 contained two, and eight isolates had three resistance genes. PFGE indicated a clonal relationship among K. pneumoniae isolates. It was not possible to establish a clonal relationship between Enterobacter sp. isolates. The results highlight the potential of these resistance genes to spread in the polluted environment and to present a health risk to communities. This report is the first description of these resistance genes present in environmental samples other than a hospital in the city of Porto Alegre/RS.

Past and Present Perspectives on β-Lactamases

“…This partially explains the continued presence of antibiotic resistance genes in apparently naive environments (45,46) and the perpetuation of ␤-lactamase genes encoding common TEM, SHV, and OXA enzymes. It is notable that TEM-1 and, to a lesser extent, OXA-1, two of the first known plasmid-encoded ␤-lactamases, have not disappeared and are frequently identified in contemporary, multidrug-resistant, clinical, and environmental isolates (132,205,206), perhaps because of their exquisite ability to hydrolyze inexpensive penicillins that are still used therapeutically in community settings. However, there is great concern about environmental contamination in public water supplies by ␤-lactamase-producing antibiotic-resistant pathogens.…”

Distribution of Beta-Lactamase Producing Gram-Negative Bacterial Isolates in Isabela River of Santo Domingo, Dominican Republic

“…CTX-M genes have been associated with pathogenic bacteria of the Enterobacteriaceae family as well as mobile genetic elements (Cantón and Coque, 2006;Bevan et al, 2017). It has also been described in similar lotic environments by Alves et al (2020), de Oliveira et al (2017), Nascimento et al (2017), and Dropa et al (2016.…”

Extended Spectrum Beta-Lactamase-Producing Gram-Negative Bacteria Recovered From an Amazonian Lake Near the City of Belém, Brazil

“…The occurrence of ESBL genes, including bla CTX–M , in different aquatic systems has been reported in several countries (Tacão et al, 2012; Zurfluh et al, 2013; Alves et al, 2014; Nascimento et al, 2017). In Brazilian aquatic systems, clinically relevant bacteria producing CTX-M enzymes have been recently described, e.g., in lakes (Nascimento et al, 2017), rivers (de Oliveira et al, 2017), wastewater (Dropa et al, 2016) and coastal water (Sellera et al, 2017). For the measures to be effective further studies are required to reveal which bacteria and which resistance and transfer mechanisms are present in these settings.…”