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Bioinformatic analysis of the data on the genome sequencing of the isolates of the Streptococcuspneumoniae clonal complex SS320 from the Russian Federation, as well as the data on SS320 isolates from public sources in the penicillin resistant isolates resulted in detection of 139 missense mutations in 45 genes. In addition to the mutations in the genes of the main penicillin-binding proteins (PSB - PBP1A, PBP2B and PBP2X) there was detected high frequency of mutations in the genes of the (division and cell wall) dcw-cluster, as well as in RegR protein belonging to the transcription regulators of the LacI/GaIR family. Development of resistance to beta-lactams in S.pneumoniae is defined not only by modification of the PSB, but also by adaptive changes in the metabolic pathways involved in the bacterial cell growth and division.

Antibiotic susceptibility of 119 coagulase-negative staphylococci isolated at hospitals of St. Petersburg and Moscow was investigated and estimated at the local laboratories as oxacillin resistant. The following species were identified: Staphylococcus epidermidis, S. haemolyticus, S. hominis, S.capitis, S. simulans, S. pettenkoferi, S. lentus, S. carnosus and S. warneri. The oxacillin resistance was confirmed in 79.8% of the isolates. The frequency of the associated resistance to non-beta-lactams was much higher in the oxacillin resistant isolates vs. the oxacillin susceptible ones. When the CLSI and EUCAST susceptibility criteria were used, 1-3% difference in the resistance levels was recorded. Among the oxacillin resistant isolates the frequency of resistance to gentamicin, ciprofloxacin, erythromycin, moxifloxacin, tetracycline and clindamycin equaled 90, 88, 88, 63, 43 and 26% respectively. Two linezolid resistant isolates of S. epidermidis with lower susceptibility to tedizolid were isolated. Eight isolates of S. epidermidis showed lower resistance to mupirocin. The MIC of ceftarolin for oxacillin resistant coagulase-negative staphylococci varied from 0.5 to 2.0 mcg/ml, while for the oxacillin susceptible ones it was lower than 0.25 mcg/ml. No resistance to tigecyclin and vancomycin was observed.

The surveillance of the serotype pattern and antibiotic resistance of S. pneumoniae in various geographical regions is required for the validity of rational etiotrophic therapy of pneumococcal infections and the choice of the optimal vaccines for their prophylaxis. 250 S. pneumoniae isolates from children with acute otitis or pneumonia and healthy carriers in St. Petersburg in 2010-2013 were investigated. The analysis of the serotype pattern of the pneumococci showed that 13-valent conjugate vaccine was the most active (86.1% of pneumococci causing pneumonia and 86.4% of pneumococci causing acute otitis). The isolates were higly resistant to beta-lactams and macrolides. By the EUCAST criteria, the decrease in the susceptibility to penicillin, cefotaxime, erythromycin and ceftarolin was observed in 32.4%, 14%, 33.2 and 6% of the isolates respectively. 22.4% of the isolates showed associate resistance to penicillin and erythromycin.. No resistance to moxifloxacin was detected. The frequency of resistance to tetracycline, co-trimoxasole and chloramphenicol in various patients ranged within 30-50%. The prevalence of the antibiotic resistance was mainly characteristic of the isolates serotypes 19A, 19F, 14 and serogroup 6.

The results of the multicentre trial on estimation of MRSA antibiotic susceptibility to 17 antibiotics are presented. 474 nonrepeting isolates of MRSA (mecA+), collected in 2011-2014 in 10 cities of the Russian Federation were used in the trial. The antibiotic susceptibility was determined by the method of serial microdilutions in broth with estimation of the MICs in accordance with the international standards CLSI 2014 and EUCAST 2014. The highest levels of the MRSA resistance were stated against ciprofloxacin--92%(MIC50 32 mcg/ml), gentamicin--85% (MIC50 128 mcg/ml), erythromycin--54% (MIC50 32-mcg/ml) and clindainycin - 45% (MIC50 0.03 mcg/ml), as well as against rifampicin--38% (MIC50 0.06 mcg/ml). The frequency of MRSA isolated at the vancomycin dose of 2 mcg/ml equaled 26%. No correlation of the decrease in susceptibility to vancomycin and rifampicin was observed. In 5% of MRSA isolated from infected surgical wounds in patients with bone infection or sepsis, there was observed a decrease in the susceptibility to ceftarolin (MIC 2-4 mcg/ml). Co-trimoxasole, fusidic acid (MIC50 0.06 mcg/ml) and mupirocin (MIC50 0.5 mcg/ml) showed high antibacterial activity, 93-98% of the isolates being susceptible to the drugs. No resistance to linezolid and tigecycline was detected. By the associate resistance spectrum, most of the MRSA isolates were characterized by resistance to drugs of 3-7 groups (56%). The phenotypes with simultaneous resistance to drugs of 8-10 groups amounted to 6%. As a whole, 70 variants of associate resistance combinations were detected.

Prevalence and therapy of infections due to MRSA remain one of the most serious problems in the world. Therefore, correct laboratory identification of the MRSA phenotype based on the use of the marker antibiotic cefoxitine, as a more susceptibile one vs. oxacillin, is of great importance. There is lately being observed a tendency towards emergence of strains with lower susceptibility to the last reserve drugs protecting from MRSA, i. e. vancomycin and daptomycin. Susceptibility of MSRA to these drugs was not investigated in Russia and there are no data on the prevalence of the VISA and hVISA phenotypes. The results of our study on estimation of susceptibility of 316 MRSA isolates from several regions of Russia to oxacillin, cefoxitine, vancomycin and daptomycin are presented herein. It was shown that the ranges of the oxacillin MIC were extremely wide, i. e. 0.5 to 512 mcg/ml, while 2.2 +/- 1% of the isolates was susceptible by the phenotype to oxacillin, in spite of the mecA gene presence. As for cefoxitine, the MRSA isolates were rather resistant to it at the MIC16 mcg/ml. The tests with serial microdilutions revealed that 30.7 +/- 7% of the isolates had a critical level of susceptibility to vancomycin at the MIC 2 mcg/ml. The E-tests revealed 1.3 +/- 1% of the isolates which were susceptible at the MIC 2-4 mcg/ml. The MRSA isolates were highly susceptible to daptomycin, while high levels of the MIC (2 mcg/ml) were characteristic of 2.8 +/- 1% of the isolates. Cross reduction of the susceptibility to vancomycin and daptomycin was observed.

Methicillin resistant Staphylococcus aureus (MRSA) is the main pathogen of hospital- and community-associated infections. Methicillin resistance is due to mecA gene located in a mobile complex element, staphylococcal cassette chromosome mec (SCCmec). The structure of the staphylococcal cassettes is diverse. At present eleven types of the cassettes are described. Types I-IV SCCmec are always associated with epidemiologically significant genetic lines of Staphylococcus. Thus, the pandemic hospital-associated MRSA (HA MRSA) belonging to CC5 and CC8 are of the types I-III SCCmec. The prevalence of virulent community-associated MRSA (CA MRSA) in many regions of the world is first of all connected with the characteristics of the type IV SCCmec structure and the presence of a recently described arginine catabolic mobile element (ACME) increasing the colonization activity of Staphylococcus. The review presents the up-to-date data on the origin, genetic structure and classification of SCCmec. Global genetic lines of MRSA are described and the problem of CA MRSA is discussed.