RESEARCH – November 2008

The spectrum and antibiotic susceptibility of anaerobic bacteria isolated in Tartu University Hospital


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AIM. To analyse the susceptibility patterns of the anaerobes isolated from clinical materials in Tartu University Hospital and to compare them to the susceptibility patterns of parodontitis isolates and to data from other studies.
MATERIAL AND METHODS. All anaerobes, isolated from 2001 to 2006 in the Laboratory of Microbiology, Tartu University Hospital, were divided into groups according to family taxonomy. The data of susceptibility to metronidazole, benzylpenicillin, clindamycin and ampicillin/sulbactam was  collected and beta-lactamase production was determined. The isolates of parodontitis pathogens (from routine testing and from testing under grant 5657) were divided into groups. The grant isolates were tested for metronidazole and clindamycin, and betalactamase production was determined.
RESULTS. A total of 1059 strains of anaerobic bacteria (Bacteroides spp. 44.5%, Prevotella spp. 22.7%, Peptostreptococcus spp. 13.6%,Fusobacterium spp. 12.3%) were isolated from clinical materials. Of the anaerobic pathogens of parodontitis (241),  Prevotella spp. 48% and Fusobacterium spp. 19% were isolated most frequently. The isolated anaerobes were susceptible to the majority of antimicrobial agents tested. Metronidazole resistance was not found among Gram-negative rods but was relatively high among Gram-positive cocci. Clindamycin and ampicillin/sulbactam were effective against all groups of anaerobes. Beta-lactamase production was detected in 7–54% of the anaerobes. The rate of beta-lactamase positive strains was high among Porphyromonas spp. and Prevotella spp. The anaerobic pathogens of parodontitis proved to be more susceptible to  antibiotics compared to the anaerobes isolated from clinical materials.
CONCLUSIONS. The anaerobes isolated in the Laboratory of Microbiology, Tartu University Hospital, were susceptible to the majority of antibiotics tested. The frequency of beta-lactamase production and resistance to benzylpenicillin were relatively high, but beta-lactam and beta-lactamase inhibitor combinations were effective against almost all anaerobic isolates. Detection of parodontitis pathogens from the gingival-pocket material helps monitore local susceptibility patterns, which may be necessary for selection of initial empirical therapy.