Low Prevalence of Carbapenem-Resistant Bacteria in River Water: Resistance Is Mostly Related to Intrinsic Mechanisms

Abstract

Carbapenems are last-resort antibiotics to handle serious infections caused by multiresistant bacteria. The incidence of resistance to these antibiotics has been increasing and new resistance mechanisms have emerged. The dissemination of carbapenem resistance in the environment has been overlooked. The main goal of this research was to assess the prevalence and diversity of carbapenem-resistant bacteria in riverine ecosystems. The presence of frequently reported carbapenemase-encoding genes was inspected. The proportion of imipenem-resistant bacteria was on average 2.24 CFU/ml. Imipenem-resistant strains (n=110) were identified as Pseudomonas spp., Stenotrophomonas maltophilia, Aeromonas spp., Chromobacterium haemolyticum, Shewanella xiamenensis, and members of Enterobacteriaceae. Carbapenem-resistant bacteria were highly resistant to other beta-lactams such as quinolones, aminoglycosides, chloramphenicol, tetracyclines, and sulfamethoxazole/trimethoprim. Carbapenem resistance was mostly associated with intrinsically resistant bacteria. As intrinsic resistance mechanisms, we have identified the blaCphA gene in 77.3% of Aeromonas spp., blaL1 in all S. maltophilia, and blaOXA-48-like in all S. xiamenensis. As acquired resistance mechanisms, we have detected the blaVIM-2 gene in six Pseudomonas spp. (5.45%). Integrons with gene cassettes encoding resistance to aminoglycosides (aacA and aacC genes), trimethoprim (dfrB1b), and carbapenems (blaVIM-2) were found in Pseudomonas spp. Results suggest that carbapenem resistance dissemination in riverine ecosystems is still at an early stage. Nevertheless, monitoring these aquatic compartments for the presence of resistance genes and its host organisms is essential to outline strategies to minimize resistance dissemination.

Prevalence and characterization of carbapenem‐resistant bacteria in water bodies in the Los Angeles–Southern California area

“…Most efforts to detect these bacteria have focused on healthcare (Conlan et al., ; Doi & Paterson, ; Guh et al., ; Gupta et al., ) or immediately related settings such as hospital wastewater (Chagas, Seki, da Silva, & Asensi, ; Nasri et al., ; White et al., ). However, recent findings in Europe, Africa and Asia have revealed carbapenem‐resistant bacteria and genes in freshwater and other environmental samples (Di, Jang, Unno, & Hur, ; Girlich, Poirel, & Nordmann, ; Henriques et al., ; Isozumi et al., ; Poirel et al., ; Potron, Poirel, Bussy, & Nordmann, ; Tacão, Correia, & Henriques, ; Zurfluh, Hachler, Nuesch‐Inderbinen, & Stephan, ).…”

Chromosome-Based bla OXA-48 -Like Variants in Shewanella Species Isolates from Food-Producing Animals, Fish, and the Aquatic Environment

“…Carbapenemase-producing microorganisms are increasingly reported in foodproducing animals (2,3), the food supply (4), and the environment (5,6). These findings are fueling a debate on the hazards for public health (7,8), and authorities have rising concerns regarding the appearance of carbapenem resistance in food animal ecosystems (9).…”

“…Interestingly, two of these isolates (F2. (17,23) and are commonly detected in the aquatic environment, where intrinsically resistant bacteria like Shewanella thrive (6). Given the absence of specific phenotypic tests, high-level temocillin resistance (MIC Ͼ64 ml/liter) has been suggested as a first step in identifying OXA-48 producers (9).…”

Molecular Epidemiology of KPC-2 Producing Klebsiella pneumoniae

“…Horizontal Gene Transfer (HGT) -between bacteria [4,14,15]. Furthermore, the capacity of the K. pneumoniae to colonize medical equipment and to survive for long periods of time, at extreme temperature in the environment, explains why this pathogen can also be isolated from hospital environment and play an important role in the horizontal transfer of antibiotic resistance, acting also as an efficient donor and receptor [4,13,[16][17][18][19]. The events observed in the present study, suggest that asymptomatic carriers, such as health professionals and their flow between different hospitals; patient or other people who move through hospitals, may be contributing to the local dissemination of these clones, which may affect vulnerable patients [13].…”

“…In the present study, the clones were sensitive to colistin and to amikacin. Since the KPC-producing bacteria present a resistance profile to different classes of antibiotics, such as monobactams, carbapenems and broad spectrum cephalosporins, the last therapeutic options that remain is polymyxin B, colistin and fosfomycin [3,13,19]. A serious prophylactic action in the health centers with focus on control measure of the environment, contact precautions, hand hygiene, early identification of asymptomatic carriers, antimicrobial stewardship and the implementation of the infection control guideline, are obligatory to prevent, control or at least to reduce the risks of dissemination of those virulent clones [20].…”