Moritz Charles F, Snyder Robert E, Riley Lee W, Immke Devin W, Greenfield Ben K
School of Public Health, University of California, Berkeley, CA 94720, USA.
Department of Environmental Sciences, Southern Illinois University, Edwardsville, IL 62026, USA.
Antibiotics (Basel). 2020 Jul 10;9(7):400. doi: 10.3390/antibiotics9070400.
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 spp. (40%), spp. (36%), spp. (11%), and spp. (4%). Of the 55 isolates tested for antimicrobial resistance, the spp. showed the most notable resistance profiles. Most (96%) were resistant to ampicillin, and two isolates showed multidrug-resistant phenotypes: (cefotaxime, ampicillin, gentamicin, cefoxitin) and (cefotaxime, ampicillin, cefoxitin). Targeted testing for class 1 integrons and presence of β-lactam-resistance gene variants TEM, SHV, OXA, CTX-M, and 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.
我们评估了来自一个大型城市化河口的革兰氏阴性菌的抗菌药物耐药性流行情况，并筛选了临床相关的β-内酰胺酶耐药性决定因素。与大量记录废水处理排放点及其他局部水体污染源附近存在潜在有害耐药性决定因素的文献不同，我们采用概率调查设计来检测潮间带和近岸沉积物。我们将来自美国加利福尼亚州旧金山湾周围40个潮间带和浅潮下带区域的环境样本接种在添加药物的麦康凯琼脂平板上，并对分离菌株进行抗菌药物耐药性检测以及临床相关β-内酰胺酶耐药性决定因素的检测。在鉴定出的74株分离菌株中，最常分离到的菌属是 菌属（40%）、 菌属（36%）、 菌属（11%）和 菌属（4%）。在检测抗菌药物耐药性的55株分离菌株中， 菌属显示出最显著的耐药谱。大多数（96%）对氨苄西林耐药，有两株分离菌株表现出多重耐药表型： （对头孢噻肟、氨苄西林、庆大霉素、头孢西丁耐药）和 （对头孢噻肟、氨苄西林、头孢西丁耐药）。针对1类整合子以及β-内酰胺耐药基因变体TEM、SHV、OXA、CTX-M和碳青霉烯酶（KPC）的靶向检测未发现任何携带这些耐药性决定因素的分离菌株。因此，虽然从环境沉积物中分离出了耐药革兰氏阴性菌，但未发现临床相关菌株或可移动的β-内酰胺耐药性决定因素。这表明在这个管理良好的城市化河口，革兰氏阴性菌目前不太可能构成重大的人类暴露风险。
