Fatal case of ST8/SCCmecIVl community-associated methicillin-resistant Staphylococcus aureus infection in Japan.

Community-associated methicillin-resistant Staphylococcus aureus (CA-MRSA) with ST8/SCCmecIV threatens human health. However, its pathogenesis remains unclear. ST8 CA-MRSA (CA-MRSA/J) with SCCmecIVl, which carries the large LPXTG-motif-containing putative adhesin gene, spj, has emerged in Japan. We present the first reported case of death from CA-MRSA/J. The patient was a 64-year-old woman with iliopsoas abscesses complicated by septic pulmonary embolism and multiorgan abscesses. Vancomycin, arbekacin, daptomycin and rifampicin were ineffective. CA-MRSA/J was resistant to erythromycin, clindamycin and antiseptics and was invasive in a HEp-2 cell assay, in contrast to skin-derived villous-adherent CA-MRSA/J. This suggests the strongly invasive pathotype of CA-MRSA/J.

[Antibiotic Resistance of MRSA in the Russian Federation].

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.

[Estimation of MRSA susceptibility to oxacillin, cefoxitine, vancomycin and daptomycin].

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 MIC > 16 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.