In Vitro Antimicrobial Susceptibility of Bacterial Enteropathogens Isolated from International Travelers to Mexico, Guatemala, and India from 2006 to 2008

Abstract

The incidence rates of travelers' diarrhea (TD) have remained high for the last 50 years. More recently, there have been increasing recommendations for self-initiated therapy and use of prophylactic drugs for TD. We last examined the in vitro susceptibilities of commonly used antibiotics against TD pathogens in 1997. We now examine 456 enteropathogens isolated from adult travelers to Mexico, India, and Guatemala with diarrhea acquired between 2006 and 2008 to determine changes in susceptibility against 10 different antimicrobials by the agar dilution method. Traditional antibiotics, such as ampicillin, trimethoprim-sulfamethoxazole, and doxycycline, continue to show high levels of resistance. Current first-line antibiotic agents, including fluoroquinolones and azithromycin, showed significantly higher MICs than in our earlier study, and MIC 90 levels were above the Clinical and Laboratory Standards Institute cutoffs for resistance. There were significant geographical differences in resistance patterns when Central America was compared with India. Entertoxigenic Escherichia coli (ETEC) isolates showed increased resistance to ciprofloxacin (P ‫؍‬ 0.023) and levofloxacin (P ‫؍‬ 0.0078) in India compared with Central America. Enteroaggregative E. coli (EAEC) isolates from Central America showed increased resistance to nearly all of the antibiotics tested. Compared to MICs of isolates 10 years prior, there were 4-to 10-fold increases in MIC 90 values for ceftriaxone, ciprofloxacin, levofloxacin, and azithromycin for both ETEC and EAEC. There were no significant changes in rifaximin MICs. Rising MICs over time imply the need for continuous surveillance of susceptibility patterns worldwide and geographically specific recommendations in TD therapy.

ACG Clinical Guideline: Diagnosis, Treatment, and Prevention of Acute Diarrheal Infections in Adults

“…One study showed that azithromycin had high activity against TD pathogens but another suggested that concentrations needed to inhibit diarrheagenic E. coli have been increasing over the past decades. ( 26 ) In vitro studies showed increasing resistance among Campylobacter isolates in Nepal and Th ailand but clinical failures have not been reported ( 139 ).…”

“…Th e emergence of fl uoroquinolone resistance to commonly encountered TD pathogens may be a factor today if these studies were replicated ( 139,247,248 ). Furthermore, relative to rifaximin, the safety profi le for fl oroquinolones is less favorable given the association with tendonopathies and the systemic broad-spectrum nature of this antibiotic with attendant pressures on systemic drug-resistant pathogens of importance ( 132 ).…”

Recent Advances in Understanding Enteric Pathogenic Escherichia coli

“…(i) Treatment of traveler's diarrhea. Antibiotics are generally recommended for treatment of traveler's diarrhea, but because EAEC is increasingly resistant to various antibiotics, selection of the appropriate antibiotic should take into account the region of the world where the infection was acquired, as there are different antimicrobial susceptibility patterns for each geographical region (670)(671)(672). Like Shigella infections, EAEC infections are often successfully treated with ciprofloxacin and other fluoroquinolones, but there are multiple antibiotic-resistant strains (597,673).…”

Travel to Tropical Countries: A Review of Travel-Related Infectious Diseases

“…Travelers are advised to carry with them a fluoroquinolone antibiotic (ciprofloxacin) in case they develop severe diarrhea. Quinolones are contra-indicated in pregnancy, and quinolone-resistant campylobacter and other infections are prevalent in some countries especially in South Asia [47]. Azithromycin is recommended as an alternative antibiotic [48].…”

“…In general, hot cooked food and sealed bottled liquids should be advised. Some of the most common bacterial pathogens associated with TD include campylobacter, salmonella, shigella and escherichia coli [46,47]. Travelers are advised to carry with them a fluoroquinolone antibiotic (ciprofloxacin) in case they develop severe diarrhea.…”