J Travel Med. 2021 Apr 8:taab042. doi: 10.1093/jtm/taab042. Online ahead of print.
BACKGROUND: Antibiotics are no longer the primary approach for treating all travelers' diarrhea (TD): most cases resolve without antibiotics and using them predisposes to colonization by multidrug-resistant bacteria. Data are accumulating on increasing resistance among TD pathogens, yet research into the most common agents, diarrheagenic Escherhichia coli (DEC), remains limited.
METHODS: A total of 413 travelers to the (sub)tropics were analyzed for travel-acquired diarrheal pathogens and ESBL-PE. To identify ESBL-producing DEC, ESBL-producing E. coli (ESBL-EC) isolates were subjected to multiplex qPCR for various DEC pathotypes: enteroaggregative (EAEC), enteropathogenic (EPEC), enterotoxigenic (ETEC), enteroinvasive (EIEC), and enterohemorrhagic (EHEC) E. coli. For a literature review, we screened studies among travelers and locals in low- and middle-income countries (LMIC) on the frequency of ESBL-producing DEC, and among travelers, also DEC with resistance to ciprofloxacin, azithromycin, and rifamycin derivatives.
RESULTS: Our rate of ESBL-EC among all DEC findings was 2.7% (13/475); among EAEC 5.7% (10/175), EPEC 1.1% (2/180), ETEC 1.3% (1/80), and EHEC (0/35) or EIEC 0% (0/5). The literature search yielded three studies reporting ESBL-EC frequency and thirteen exploring resistance to TD antibiotics among travel-acquired DEC. For EAEC and ETEC, the ESBL-EC rates were 10-13% and 14-15%, resistance to fluoroquinolones 0-42% and 0-40%, azithromycin 0-29% and 0-61%, and rifaximin 0% and 0-20%. The highest rates were from the most recent collections. Proportions of ESBL-producing DEC also appear to be increasing among locals in LMICs and even carbapenemase-producing DEC were reported.
CONCLUSIONS: ESBL producers are no longer rare among DEC and the overall resistance to various antibiotics is increasing. The data predict decreasing efficacy of antibiotic treatment, threatening its benefits, for disadvantages still prevail when efficacy is lost.