Related Experiment Videos
In vitro antimicrobial susceptibility testing of bacterial enteropathogens causing traveler's diarrhea in four
H Gomi1, Z D Jiang, J A Adachi
1Center for Infectious Diseases, University of Texas-Houston Medical School and School of Public Health, Houston, Texas, USA.
Abstract:
The emergence of resistant enteropathogens has been reported worldwide. Few data are available on the contemporary in vitro activities of commonly used antimicrobial agents against enteropathogens causing traveler's diarrhea (TD). The susceptibility patterns of antimicrobial agents currently available or under evaluation against pathogens causing TD in four different areas of the world were evaluated. Pathogens were identified in stool samples from U.S., Canadian, or European adults (18 years of age or older) with TD during 1997, visiting India, Mexico, Jamaica, or Kenya. MICs of 11different antimicrobials were determined against 284 bacterial enteropathogens by the agar dilution method. Ciprofloxacin, levofloxacin, ceftriaxone, and azithromycin were highly active in vitro against the enteropathogens, while traditional antimicrobials such as ampicillin, trimethoprim, and trimethoprim/sulfamethoxazole showed high levels and high frequencies of resistance. Rifaximin, a promising and poorly absorbable drug, had an MIC at which 90% of the strains tested were inhibited of 32 microg/ml, 250 times lower than the concentration of this drug in the stools. Amdinocillin, nalidixic acid, and doxycycline showed moderate activity. Fluoroquinolones are still the drugs of choice for TD in most regions of the world, although our study has a limitation due to the lack of Escherichia coli samples from Kenya and possible bias in selection of the patients for evaluation. Azithromycin and rifaximin should be considered as promising new agents. The widespread in vitro resistance of the traditional antimicrobial agents reported since the 1980s and the new finding of resistance to fluoroquinolones in Southeast Asia are the main reasons for monitoring carefully the antimicrobial susceptibility patterns worldwide and for developing and evaluating new antimicrobial agents for the treatment of TD.
Insights
Antimicrobial resistance is a growing concern for traveler's diarrhea (TD). Newer agents like fluoroquinolones, azithromycin, and rifaximin show promise, while older drugs are increasingly ineffective against TD pathogens.
Area of Science:
- Infectious Diseases
- Microbiology
- Pharmacology
Background:
- Emerging resistance in enteropathogens poses a global health challenge.
- Limited data exist on current antimicrobial effectiveness against traveler's diarrhea (TD) pathogens.
Purpose of the Study:
- To evaluate in vitro antimicrobial susceptibility patterns of TD pathogens.
- To assess commonly used and emerging antimicrobial agents against TD-causing bacteria.
Main Methods:
- Collected stool samples from adults with TD in India, Mexico, Jamaica, and Kenya (1997).
- Identified bacterial enteropathogens and determined Minimum Inhibitory Concentrations (MICs) for 11 antimicrobials using agar dilution.
- Tested 284 bacterial enteropathogens against various antimicrobial agents.
Main Results:
- Ciprofloxacin, levofloxacin, ceftriaxone, and azithromycin demonstrated high in vitro activity.
- High resistance rates were observed for ampicillin, trimethoprim, and trimethoprim/sulfamethoxazole.
- Rifaximin showed potent activity (MIC90 = 32 microg/ml), significantly lower than fecal concentrations. Fluoroquinolones remain effective, but resistance is emerging in some regions.
Conclusions:
- Fluoroquinolones are currently preferred for TD, but emerging resistance necessitates monitoring.
- Azithromycin and rifaximin are promising alternatives for TD treatment.
- Continued surveillance of antimicrobial susceptibility and development of new agents are crucial for combating TD.