Department of Medical Microbiology, Fundación Jiménez Díaz, Avenida Reyes Católicos 2, 28040 Madrid, Spain
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Abstract |
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Introduction |
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Materials and methods |
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Two hundred and eighty-eight recent isolates of enteropathogenic bacterial isolates from patients with acute gastroenteritis were studied, including 106 Salmonella spp. (75 Salmonella enteritidis, 19 Salmonella typhimurium, five Salmonella virchow, two Salmonella hadar, two Salmonella tshiongwe, one Salmonella newport, one Salmonella ohio and one Salmonella georgia), 32 H. alvei, 22 Yersinia enterocolitica, 21 Shigella spp., (15 Shigella sonnei, five Shigella flexneri and one Shigella boydii), 16 Aeromonas spp. (12 Aeromonas hydrophila and four Aeromonas sobria) and 91 Campylobacter jejuni. The strains were stored in skimmed milk at 80°C until studied. All infections were community acquired in Spain. None of the isolates was known to have been obtained from cases of travellers' diarrhoea.
Antimicrobials
The antibiotics tested were gemifloxacin, trovafloxacin, grepafloxacin, ciprofloxacin, ofloxacin, norfloxacin, levofloxacin, nalidixic acid, amoxycillin, cefotaxime, gentamicin, doxycycline, colistin, co-trimoxazole and, for C. jejuni, erythromycin. Each was provided as a powder of known potency by SmithKline Beecham Pharmaceuticals, Harlow, UK.
Antimicrobial susceptibility tests
MICs were determined by an agar dilution method6 on MuellerHinton agar (Difco Laboratories, Detroit, MI, USA) supplemented with 5% sheep blood for C. jejuni isolates. The plates were incubated aerobically at 35°C for 24 h, except for C. jejuni, where a microaerophilic atmosphere was obtained by using Campy Pack (Becton Dickinson, Cockeysville, MD, USA). Incubation was for 48 h. All organisms were tested with an inoculum of c. 104 cfu/spot. Dilutions tested ranged from 0.015 to 128 mg/L. MICs were defined as the lowest antimicrobial concentration at which there was no visible growth. Escherichia coli ATCC 25922, Staphylococcus aureus ATCC 29213 and Pseudomonas aeruginosa ATCC 27853 were used as controls. The antimicrobial susceptibility breakpoints3,6 used to define the percentage of susceptible isolates were as follows: erythromycin, 0.5 mg/L; grepafloxacin and ciprofloxacin, 1 mg/L; colistin, co-trimoxazole, ofloxacin and levofloxacin, 2 mg/L; norfloxacin, gentamicin and doxycycline, 4 mg/L; amoxycillin and cefotaxime, 8 mg/L; and nalidixic acid, 16 mg/L. For comparison purposes the chosen breakpoint for susceptibility of gemifloxacin and trovafloxacin was 1 mg/L.
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Results |
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Seventy-seven per cent of isolates of C. jejuni were inhibited by erythromycin 0.5 mg/L. Only one isolate was highly resistant to this antimicrobial (MIC 128 mg/L); the other isolates were all inhibited by erythromycin
4 mg/L.
By weight, gemifloxacin was the most active compound tested, with 100% of isolates of each species, except for C. jejuni, being inhibited by a concentration of 0.25 mg/L.
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Discussion |
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High rates of resistance among C. jejuni strains are being described to quinolones,1,3 but erythromycin and other macrolides are active against this microorganism. The quinolone resistance in C. jejuni found in our study is higher than that reported in 1996.3 In contrast, only one isolate (1.1%) of C. jejuni showed high resistance to erythromycin. The high rates of quinolone-resistant C. jejuni in Spain seem to be associated with the massive use of these antibiotics, especially in animals.10
In conclusion, quinolones can be good choices for treating gastrointestinal infection when indicated. For C. jejuni, different antibiotics, such as erythromycin, must be considered. Gemifloxacin is a new quinolone with good in vitro activity against important gastrointestinal pathogens and could be a good choice in these infections. The present results must be assessed in the context of in vivo trials before the clinical role of this new fluoroquinolone can be determined for these infections.
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Acknowledgments |
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Notes |
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References |
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2 . Ramos, J. M., Alés, J. M., Cuenca-Estrella, M., FernándezRoblas, R. & Soriano, F. (1996). Changes in susceptibility of Salmonella enteritidis, Salmonella typhimurium, and Salmonella virchow, to six antimicrobial agents in a Spanish hospital, 19801994. European Journal of Clinical Microbiology and Infectious Diseases 15, 858.[ISI][Medline]
3 . Soriano, F., Fernández-Roblas, R., López, J. C., García-Corbeira, P. & Aguilar, L. (1994). Comparative in-vitro activity of rufloxacin with five other antimicrobial agents against bacterial enteric pathogens. Journal of Antimicrobial Chemotherapy 34, 15760.[ISI][Medline]
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Stock, I. & Wiedemann, B. (1999). An in-vitro study of the antimicrobial susceptibilities of Yersinia enterocolitica and the definition of a database. Journal of Antimicrobial Chemotherapy 43, 3745.
5 . Ismaili, A., Bouske, B., de Azavedo, I. C., Ratnam, S., Karmali, M. A. & Sherman, P. M. (1996). Heterogeneity in phenotypic and genotypic characteristics among strains of Hafnia alvei. Journal of Clinical Microbiology 34, 29739.[Abstract]
6 . National Committee for Clinical Laboratory Standards. (1997). Methods for Dilution Antimicrobial Susceptibility Tests for Bacteria that Grow AerobicallyFourth Edition: Approved Standard M7-A4. NCCLS, Villanova, PA.
7 . Guerrant, R. L. (1995). Principles and syndromes of enteric infection. In Principles and Practice of Infectious Diseases, 4th edn (Mandell, G. L., Douglas, R. G., Bennett, J. E. & Dolin, R., Eds), pp. 94562. Churchill Livingstone, New York, NY.
8 . Threlfall, E. J., Ward, L. R. & Rowe, B. (1999). Resistance to ciprofloxacin in non-typhoidal salmonellas from humans in England and Walesthe current situation. Clinical Microbiology and Infection 5, 1304.[Medline]
9 . Burgos, A., Quindos, G., Martinez, R., Rojo, P. & Cisterna, R. (1990). In vitro susceptibility of Aeromonas caviae, Aeromonas hydrophila and Aeromonas sobria to fifteen antibacterial agents. European Journal of Clinical Microbiology and Infectious Diseases 9, 4137.[ISI][Medline]
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.
Garau, J., Xercavins, M., Rodriguez-Carballeira, M., Gómez-Vera, J. R., Coll, I., Vidal, D. et al. (1999). Emergence and dissemination of quinolone-resistant Escherichia coli in the community. Antimicrobial Agents and Chemotherapy 43, 273641.
Received 6 March 2000; returned 9 June 2000; revised 3 July 2000; accepted 29 August 2000