Antimicrobial Drug-Resistant Gram-Negative Saprophytic Bacteria Isolated from Ambient, Near-Shore Sediments of an Urbanized Estuary: Absence of β-Lactamase Drug-Resistance Genes

Abstract

<jats:p>We assessed the prevalence of antimicrobial resistance and screened for clinically relevant β-lactamase resistance determinants in Gram-negative bacteria from a large urbanized estuary. In contrast to the broad literature documenting potentially hazardous resistance determinants near wastewater treatment discharge points and other local sources of aquatic pollution, we employed a probabilistic survey design to examine ambient, near-shore sediments. We plated environmental samples from 40 intertidal and shallow subtidal areas around San Francisco Bay (California, USA) on drug-supplemented MacConkey agar, and we tested isolates for antimicrobial resistance and presence of clinically relevant β-lactamase resistance determinants. Of the 74 isolates identified, the most frequently recovered taxa were Vibrio spp. (40%), Shewanella spp. (36%), Pseudomonas spp. (11%), and Aeromonas spp. (4%). Of the 55 isolates tested for antimicrobial resistance, the Vibrio spp. showed the most notable resistance profiles. Most (96%) were resistant to ampicillin, and two isolates showed multidrug-resistant phenotypes: V. alginolyticus (cefotaxime, ampicillin, gentamicin, cefoxitin) and V. fluvialis (cefotaxime, ampicillin, cefoxitin). Targeted testing for class 1 integrons and presence of β-lactam-resistance gene variants TEM, SHV, OXA, CTX-M, and Klebsiella pneumonia carbapenemase (KPC) did not reveal any isolates harboring these resistance determinants. Thus, while drug-resistant, Gram-negative bacteria were recovered from ambient sediments, neither clinically relevant strains nor mobile β-lactam resistance determinants were found. This suggests that Gram-negative bacteria in this well-managed, urbanized estuary are unlikely to constitute a major human exposure hazard at this time.</jats:p>

Seasonal resistome diversity and dissemination of WHO priority antibiotic-resistant pathogens in Lebanese estuaries

“…Similar to our findings, multidrug-resistant Enterobacterales, namely Enterobacter cloacae, Escherichia coli , and Klebsiella pneumoniae , were isolated from the human-impacted Melayu river estuary in Malaysia with antibiotic resistance attaining 100% to antibiotics such as cefotaxime 48 . Inversely, resistant Enterobacterales in the urbanized San Francisco Bay were absent from the near-shore sediments suggesting that urbanized estuaries may not constitute a major human exposure hazard when secondary and tertiary treatment operations and control measures for all wastewaters that drain into the studied environment are implemented 49 .…”

Green synthesis of silver nanoparticles through oil: Promoting full-thickness cutaneous wound healing in methicillin-resistant Staphylococcus aureus infections

“…In this context, infection prevention and control are critical to prevent the spread of multidrug-resistant bacteria. E. coli as a common pathogen of bacterial diseases can incorporate drug-resistant genes into other bacteria by means of horizontal transmission and vertical transmission, thus creating more drug-resistant strains ( Moritz et al, 2020 ; Le Guern et al, 2021 ). The resistance mechanism of MRSA is that the binding protein has a very low affinity with antibacterial drugs, which can promote the synthesis of bacterial cell wall.…”

Resistome Diversity and Dissemination of WHO Priority Antibiotic Resistant Pathogens in Lebanese Estuaries

“…Studies in lower income countries with lack of sanitation measures and operational wastewater treatment systems have shown high levels of ARB and ARGs that were significantly correlated with human gut bacteria and pathogens [23,47,48]. Inversely, resistant Enterobacterales in the urbanized San Francisco Bay were absent from near-shore sediments, suggesting that urbanized estuaries may not constitute a major human exposure hazard when secondary and tertiary treatment operations and control measures for all wastewaters that drain into the studied environment are implemented [49]. Altogether, the presence of ESBL and carbapenemase-producing pathogens and corresponding ARGs in the Lebanon estuaries raises concerns and warrants further attention [50].…”