Multiple outbreaks of nosocomial salmonellosis in Russia and Belarus caused by a single clone of Salmonella enterica serovar Typhimurium producing an extended-spectrum beta-lactamase.

Thirty-four cefotaxime-resistant Salmonella enterica serovar Typhimurium isolates representative of the isolates that caused outbreaks of gastroenteritis in 10 hospitals in seven regions of Russia and Belarus from 1994 to 2003 were analyzed. All isolates produced the CTX-M-5-like extended-spectrum beta-lactamase, which confers high-level resistance to cefotaxime and ceftriaxone and decreased susceptibility to ceftazidime. The bla(CTX-M) genes were located on small (7.4- to 12-kb) non-self-transferable plasmids approximately 20 bp downstream of the ISEcp1 insertion sequences. Some isolates carried additional conjugative plasmids mediating resistance to penicillin-inhibitor combinations and various non-beta-lactam agents, including tetracycline, chloramphenicol, gentamicin, tobramycin, and co-trimoxazole. Despite the minor differences in susceptibility patterns, all isolates were considered clonally related on the basis of arbitrarily primed PCR and pulsed-field gel electrophoresis analysis. The similarities of the restriction profiles of the CTX-M-coding plasmids further supported the clonal origin of these isolates.

[Sensitivity of Corynebacterium diphtheriae isolated in Saint-Petersburg to antibacterial drugs]. / Chuvstitel'nost' k antibakterial'nym preparatam Corynebacterium diphtheriae, vydelennykh v Sankt-Peterburge.

One hundred and thirty strains of Corynebacterium diphtheriae isolated in St. Petersburg (42 toxigenic and 88 nontoxigenic) were tested with the method of serial dilutions in solid media for their susceptibility to 20 antibacterial drugs. The MICs of the drugs for the isolates ranged from < or = 0.015 to > or = 32.0 micrograms/ml. 13 per cent of the isolates was resistant at least to one antibacterial drug. The isolates resistant to erythromycin (11.5 per cent), lincomycin (11.5 per cent) and trimethoprim (8.5 per cent) were most frequent. 3 isolates (2.3 per cent) had multiple resistance to 8 drugs: benzylpenicillin, ampicillin, oxacillin, chloramphenicol, erythromycin, lincomycin, trimethoprim, and nitroxolin. No significant differences in the susceptibility of the toxigenic and nontoxigenic strains of C. diphtheriae were detected. Gentamicin, rifampicin, tetracycline, doxycycline and pefloxacin were the most active antibiotics.

A plasmid-mediated beta-lactamase conferring resistance to cefotaxime in a Salmonella typhimurium clone found in St Petersburg, Russia.

Four clinical and two environmental isolates of cefotaxime-resistant Salmonella typhimurium strains collected in St Petersburg, Russia, were studied. Molecular typing demonstrated that they constituted a single clone. The isolates expressed a cefotaxime-hydrolysing beta-lactamase with a pl of 8.4. The enzyme was encoded by a 12 kb plasmid which did not hybridize with TEM, SHV or ampC probes.

[Susceptibility of Corynebacteria isolated in St Petersburg to antibacterial drugs]. / Chuvstvitel'nost' k antibakteral'nym peparatam korinebakteril, vydelennykh v Sankt-Peterburge.

Susceptibility of 150 Corynebacterium isolates (91 strains of C.pseudodiphtheriticum and 59 strains of the ANF group corynebacteria) to 21 antibacterial drugs was determined by the method of serial dilutions in a solid medium. It was shown that the MIC of the drugs for the diphtheroids was within the ranges of < 0.015 to > 32.0 micrograms/ml. 66 per cent of the Corynebacterium strains circulating in St. Petersburg was resistant at least to 1 antibacterial drug. The Corynebacterium isolates with moderate resistance to erythromycin and lincomycin (57.3 per cent) and resistant to trimethoprime (16.7 per cent) were the most frequent. 8.0 per cent of the diphtheroids was resistant at least to 4 antibacterial drugs. No significant difference in the susceptibility of the ANF group corynebacteria and C.pseudodiphtheriticum to the drugs was observed. Gentamicin, rifampicin, tetracycline and doxycycline showed high activity against the corynebacteria at present circulating in St. Petersburg. When antibacterial therapy of the infection due to corynebacteria fails it is necessary to estimate antibioticograms of Corynebacterium pure cultures.

[Mechanisms of resistance to quinolones and current level of sensitivity of clinically important microorganisms to ofloxacin]. / Mekhanizmy ustoichivosti k khinolonam i sovremennyi uroven' chuvstvitel'nosti klinicheski znachimykh mikroorganizmov k ofloksatsinu.

The data on the mechanisms of microbial resistance to fluoroquinolones are presented. Comparison of the susceptibility levels of the microorganisms isolated on the territory of Russia showed that among the gram-negative opportunistic isolates 84 per cent was susceptible to ofloxacin, 45 per cent to ampicillin/sulbactam, 70 per cent to cefotaxime, 80 per cent to ceftazidime, 85 per cent to amikacin and 62 per cent to gentamicin. Among the Salmonella, Shigella and Vibrio cholerae isolates no strains were resistant to ofloxacin. Among the Salmonella isolates from patients more than 30 per cent was resistant to ampicillin, chloramphenicol, trimethoprim/sulmethoxasole and tetracycline. Among the Salmonella isolates 65 to 90 per cent was resistant to the antibiotics. Among the V.cholerae isolates 59 per cent was resistant to trimethoprim/sulmethoxasole.

[Plasmids of antibiotic-resistant strains of Salmonella of varying origin, circulating the Saint-Petersburg and Leningrad region]. / Plazmidy antibiotikorezistentnykh shtammov sal'monell razlichnogo proiskhozhdeniia, tsirkuliruiushchikh v Sankt-Peterburge i Leningradskoi oblasti.

Two hundred and twenty Salmonella strains of various serovars isolated from different source in St. Petersburg and the Leningrad Region in 1984-1991 were investigated. It was shown that drug resistance in 39.3 per cent of the strains was determined by conjugative R plasmids with the molecular weights of 28 to 90 mD which transferred at a rate of 10(-4) to 10(-8). Thirteen detected types of the Salmonella conjugative R plasmids differing in the resistance markers, molecular weights and conjugative transfer rates most frequently contained the genes responsible for the resistance to tetracycline (97.7 per cent), chloramphenicol (92.0 per cent), streptomycin (83.0 per cent), kanamycin (76.1 per cent), monomycin (76.1 per cent) and neomycin (76.1 per cent). The conjugative R plasmids were mainly detected in S> typhimurium (92.9 per cent), especially in the isolates from humans (97.6 per cent). The most frequent plasmid type in the Salmonella strains of this serovar was that with the molecular weight of 90 mD carrying the genes of resistance to chloramphenicol, tetracycline, streptomycin, kanamycin, monomycin and neomycin.

[Sensitivity to antibacterial drugs of Salmonella isolated from various sources in Saint-Petersburg and Leningrad region]. / Chuvstvitel'nost' k antibakterial'nym preparatam sal'monell, vydelennykh iz razlichnykh istochnikov v Sankt-Peterburge i Leningradskoi oblasti.

The position of antibiotic resistant cultures among 1706 strains of 85 Salmonella serovars isolated from various sources in St. Petersburg and the Leningrad Region in 1984-1991 amounted to 16.4 per cent. The highest position of such cultures was among the isolates from humans (20.9 per cent). The positions of the isolates from animals, birds and environment were practically equal (13.8, 13.8 and 13.7 per cent respectively). Strains resistant to streptomycin (11.9 per cent), tetracycline (11.5 per cent) and chloramphenicol (11.2 per cent) were the most frequent Salmonella isolates from the different sources. Rifampicin, amikacin, thienamycin, nitroxolin, oxolinic acid, dioxidin, ciprofloxacin and pefloxacin proved to be highly active against the isolates. No significant difference in the antibiotic resistance spectra of the Salmonella strains circulating in different biotopes was detected. However, among the Salmonella isolates from humans there undoubtedly predominated polyresistant strains with the resistance spectra including 10 and 6 antibacterial drugs (42.4 and 28.8 per cent of the resistant strains respectively). Sometimes there was observed correlation between the serovars of the Salmonella strains (independent of the isolation source) and the most characteristic spectra of their antibiotic resistance. Thus, the antibiotic resistant spectra of 79 per cent of the S. typhimurium strains and 82.5 per cent of the S. haifa strains resistant to one and more antibacterial drugs were the following: CmTcSmKmMmNm and ApCbCmTcSmKmMmNmGmNal respectively.