Prevalence and Antibiotic Resistance of Carbapenemase-Producing Gram-Negative Bacteria in Saint Petersburg and Some Other Regions of the Russian Federation.

Carbapenemase-producing gramnegative bacteria, which hydrolyze most offi-lactams, including carbapenems, is of global health care system threat. The number of the known carbapenemases is constantly increasing, however only four types are widely distributed: NDM-type, KPC-type, OXA-48-type and VIM-type. The frequency of carbapenemase-producing Klebsiellapneumoniae in hospitals of Saint Petersburg reached 9.2% (5.9% for NDM-type, 1.4% for OXA-48-type, 1.9% for NDM-type + OXA-48-type). Carbapenemase producers were also detected in hospitals of Moscow, Yekaterinburg, Vologda, Murmansk, Kurgan, Krasnoyarsk, Izhevsk, Krasnodar and Perm. In total 281 carbapenemase producers were recorded within 2011-2016, which were isolated from infected or colonized patients (K.pneumoniae - 247 isolates, Acinetobacter spp - 29 isolates, Enterobacter cloacae - 2 isolates, Serratia marcescens - 1 isolate, Escherichia coli - 1 isolate and Proteus mirabifis - 1 isolate). The carbapenemase-producing K.pneumoniae isolates were distinguished by considerable genetic diversity, the NDM-type carbapenemase-producers belonged to eight, KPC-type - to three and OXA-48-type - to four different sequence-types (STs) respectively. The representatives of the globally dominant genetic line, Clonal Group 258 (CG258), and also a number of the less common lines (ST147, ST273, ST307 and ST377) were detected. The K.pneumoniae strains were distinguished by a high frequency of cross-resistance and the associated resistance to antibiotics of different groups. The frequency of resistance to cephalosporins and fluoroquinolones reached 100%. Among the NDM-type carbapenemase producers the frequency of resistance to aminoglycosides exceeded 90%, among the KPC-type carbapenemase producers the frequency of resistance corresponded to 66% for amikacin and 93% for gentamicin, among the OXA-48 type carbapenemase producers the frequency of resistance was even lower (50% and 73% respectively). Approximately 80% of the NDM-type, 90% of the KPC-type and only 60% of the OXA-48-type carbapenemase producers showed a high level of resistance to imipenem and meropenem. The frequency of resistance to tigecycline varied within 6.7% to 14.8% and the frequency of resistance to polymyxin was within 4.2% to 20%. The OXA-40- and OXA-23-types carbapenemase-producing Acinetobacter spp. remained susceptible only to polymyxin. It is obvious that the possibility of antibacterial therapy of infections caused by carbapenemases producers is limited.

[Epidemic strain of methicillin-resistant Staphylococcus aureus in hospitals of Saint-Petersburg].

AIM: To study genetic characteristics of methicillin-resistant Staphylococcus aureus (MRSA) causing nosocomial infections in specialized inpatient clinics of Saint-Petersburg. MATERIALS AND METHODS: Nine cultures of S. aureus, which caused nosocomial infections in patients of 3 clinics in Saint-Petersburg, were studied by pulse-electrophoresis and spa-sequence typing. Identification of superantigens' genes pvl, sea, seb, sec, tst was performed by PCR. RESULTS: Circulation of epidemic clone BT2007 attributed to spa-type t008 was revealed. According to pulse-electrotype, this epidemic clone was related with European epidemic clones of widespread cluster A. CONCLUSION: Epidemiologic surveillance for MRSA should incorporate monitoring of clonal structure of the agent on both local (intra-clinic) and regional level.

[Emergence of the integron-positive multi-drug resistant strain of Acinetobacter baumanii in Russian hospitals].

AIM: To detect the integron-positive strains among nosocomial Acinetobacter spp. and to determine their relationship on the genotype level. MATERIALS AND METHODS: Amplification by polymerase chain reaction using primers specific to sequences of the class 1 and 2 intergrons on the genomic DNA template followed by restriction fragments length polymorphism analysis as well as RAPD-genotyping of the integron-positive strains were performed. RESULTS: Fact of spreading of Acinetobacter baumanii strain containing class 1 integron in medical centers was established. The composition of the integron's gene cassettes was analogous to worldwide (including epidemic) types. CONCLUSION: Molecular genetic analysis of the mobilized structures (integrons) under the standardization of used approaches are suitable for the surveillance for circulation of epidemic strains of nosocomial pathogens.

[Genetic variety of Acinetobacter baumannii in an intensive care unit for burn patients].

The genetic structure of A. baumannii hospital isolates, formed in the course of 2002 - 2004 in an intensive care unit for burn patients (St. Petersburg) was studied. The prolonged circulation of only some clonal strains was shown, 35% of the isolates belonged to dominating strains. Phenotypically, all cultures were characterized by resistance to the preparations of the cephalosporin row and gentamicin. The presence of class 1 integron with variable segment sized 2.5 kbp was found in the genotype of four isolates with the use the polymerase chain reaction. The restriction analysis revealed its similarity with integron, detected earlier (in 1989 - 2001 ) in A. baumannii in European hospitals abroad.

[The effect of silver sulfadiazine on Acinetobacter baumannii strains isolated in burn units].

The genotype structure and silver sulfadiazine (SDS) resistance of a number of Acinetobacter baumanii strains that circulated for a prolonged period of time in burn UCUs were studied. The most resistant strain (SDS MIC 50 mcg/ml) contained a class 1 integron with the gene of sulfonamides resistance (sul1) in its genome. Possible reasons for selection of the multiple resistance among Acinetobacter spp. in burn units are discussed.