Emergence of resistance to new antimicrobials detected among Shigella isolates in Finland

Abstract number: 1733_431

Haukka K., Siitonen A.

Objectives: In Finland most cases of shigellosis are related to traveling abroad. Shigella strains have rapidly evolved resistance to the commonly used antimicrobials. We studied the geographical resistance patterns and emerging new resistances to antimicrobials among Shigella strains isolated from patients in Finland between 1990 and 2005.

Methods: Antimicrobial drug resistance of 1834 Shigella strains isolated from Finnish patients during 1990–2005 was studied by diffusion method using discs for 12 antimicrobial agents. Since 2000, E-test for ciprofloxacin MIC determination has been done to the nalidixic acid resistant isolates (n = 65).

Results: The proportion of strains resistant to the studied antimicrobials increased during the study period. However, the frequencies of resistance differed between S. sonnei and the other Shigella serogroups. The proportion of multiresistant strains (resistant to at least 4 antimicrobials) was highest among the strains imported from China and India. Resistance to nalidixic acid has become common (87% in 2005) among the strains from the Far-East. In general, only one strain resistant to nalidixic acid per year has been obtained from the other geographical areas. In 2000–2001, susceptibility to ciprofloxacin had decreased (MIC ≥ 0.125 mg/L) in 44% and in 2004–2005 even in 83% of the nalidixic acid resistant strains. First three isolates, fully resistant to ciprofloxasin by the disc diffusion method were obtained during 2004–2005. By mid-November 2006, three more ciprofloxasin resistant isolates have been detected. All these six isolates belonged to the S. flexneri 2a serotype (MICs 3 – 32 mg/L), and most of them originated from India. Also six gentamicin, two cefotaxime and several mecillinam resistant strains have been encountered during the recent years.

Conclusion: The proportion of multiresistant Shigella strains is growing and, moreover, resistance to several new antimicrobials is emerging. The antimicrobial resistance patterns detected among the isolates from Finnish travelers reflect the resistance situation and usage of antimicrobials in the countries the infections were obtained from. Fluorokinolones, especially ciprofloxasin, are the drug of choice when treatment is needed. Unfortunately, Shigella strains seem to be rapidly evolving resistance to this group of antimicrobials as well. South and East Asia seem to be the areas where the new resistances emerge.

Session Details

Date: 31/03/2007
Time: 00:00-00:00
Session name: European Society of Clinical Microbiology and Infectious Diseases
Location: ICC, Munich, Germany
Presentation type:
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