(529.11) Phenotypical resistance profile of Stenotrophomonas maltophilia insolated from farm amimals

Poster Board Number: D59

Georgy Nikitin (Saint Petersburg State University of Veterinary Medicine), Svetlana Makavchik (Saint Petersburg State University of Veterinary Medicine), Lubov Smirnova (Saint Petersburg State University of Veterinary Medicine), Alexander Sukhinin (Saint Petersburg State University of Veterinary Medicine), Alexander Kuzmin (Saint Petersburg State University of Veterinary Medicine), Anastasia Krotova (Leningrad Interregional Veterinary Laboratory)

Stenotrophomonas maltophilia is a multidrug-resistant opportunistic pathogen. Infections caused by resistant strains of bacteria in animals are characterized by a more severe manifestation, increased duration of treatment and often leads to recurrence. Isolation, identification and determination of pathogens and interpretation of their antibioticograms are the basis of effective and rational antibiotic therapy. The aim of the study was to analyze the antibiotic resistance of Stenotrophomonas maltophilia cultures isolated in cases of respiratory diseases in livestock. The materials for the study were nose scrapings collected from 50 postpartum period cows and 69 newborn calves, and 30 horses up to 3 years old. Primary cultures of tracheal and nasal swabs from horses, cows, and calves were incubated on meat-peptone broth with 1% glucose and horse serum at 37℃ for 24 hours. After that the culture was inoculated on nutrient media such as columbia ram blood agar, chocolate agar, Endo medium and then incubated at 37℃ for 24 hours. Identification of the isolated cultures and study of their biochemical properties were performed using Nefermtest 24 (Erba Lachema, Czech Republic) test systems. Antibiotics resistance measurement was carried out by the MIC method using MicroScan WalkAway 40 plus (Siemens, Germany) automatic analyzer and GN3F, RUSTEF, NF Sensititre (Trek Diagnostic Systems, Great Britain) plates. Disk diffusion test with Mueller-Hinton agar was performed according to the recommendations of the European Committee for the determination of antibiotic susceptibility (EUCAST). Pathogenicity of cultures was studied by in vivo testing on white mice. The total number of multidrug resistant S. maltophilia isolates made up less than 5% of 149 clinical samples. Following groups of antibiotics were selected to test the antibiotic sensitivity of this bacterium based on the study’s results: penicillins combined with β-lactamase inhibitors (co-amoxiclav, ampicillin/sulbactam, ticarcillin/clavulanic acid), quinolone antibiotics (levofloxacin, moxifloxacin, ciprofloxacin, enrofloxamethacin (trimethoxoprimolamines), sulfanilamylamines (TMP/SMX),  nitrofurans (nitrofurantoin), tetracyclines (doxycycline), and macrolides (erythromycin). S. maltophilia cultures isolated from livestock were sensitive only to levofloxacin and moxifloxacin. Interpretation of antibioticograms is one of the main factors that determine the effectiveness of antibiotic therapy.