Surveillance of antimicrobial resistance of human non-typhoid Salmonellae in Bulgaria

Abstract number: P1640

Asseva G., Petrov P., Kantardjiev T.

Objectives: (1) To study the etiology of human salmonelloses in Bulgaria, (2) to perform screening for resistance to antibiotics and to establish characteristic groups for each serotype typical for the country, (3) to study with genetic methods resistant isolates.

Methods: Conventional microbiological methods for identification and serotyping of salmonellae. Resistance to 16 antimicrobial agents was studied with Bauer-Kirby disc diffusion method. Screening for ESBLs was performed using the double-disc synergy method. Plasmid analysis, PCR, sequencing, PFGE were applied for investigation of resistant isolates.

Results: For the period 1999–2006 2626 Salmonella enterica isolates belonging to non-typhoid serotypes have been studied with conventional microbiological and genetic methods. Three hundred twenty nine Salmonella isolates were resistant to antimicrobial agents. For the three leading serotypes in Bulgaria: S. Enteritidis, S. Typhimurium, S. Corvallis a statistically significant increase of resistance to all antimicrobial groups was proved. The most frequent mechanisms of resistance were as follows: S. Enteritidis – to quinolones (65.8% of isolates), S. Typhimurium – to ampicillin, carbenicillin, tetracycline, chloramphenicol (48% of isolates), S. Corvallis – to cefotaxime, ampicillin, carbenicillin, ceftazidime, cefuroxime, cephalothin, gentamicin, chloramphenicol (18.9% of isolates). Extended-spectrum b-lactamases (ESBLs) of several types: CTX-M, TEM, SHV were proved to be the main mechanism of resistance in clinical S. Corvallis isolates and were found in clinical isolates of S. Enteritidis, S. Typhimurium, S. Isangi, S. Brandenburg, S. Virchow as well.


1Clinical Salmonella isolates from nontyphoid serotypes, distrtibuted in Bulgaria demonstrated a definitive increase in resistance to all groups of anitibiotics.

2Different mechanisms of resistance were proved for the leading serotypes causing human salmonelloses in Bulgaria

3ESBLs from several types: TX-M, TEM, SHV were discovered to be the main mechanism of resistance in S. Corvallis; these enzymes were found in clinical isolates of S. Enteritidis, S. Typhimurium, S. Isangi, S. Brandenburg, S. Virchow.

4The genetic method PFGE and cluster anaslysis demonstrated distribution of 4 clones of S. Corvallis (3 of them clustering resistant isolates) 2 clones of S. Brandenburg (1 of them clustering resistant isolates).

Session Details

Date: 10/04/2010
Time: 00:00-00:00
Session name: Abstracts 20th European Congress of Clinical Microbiology and Infectious Diseases
Location: Vienna, Austria, 10 - 13 April 2010
Presentation type:
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