Phenotypic and genomic characteristics of oxacillin-susceptible mecA-positive Staphylococcus aureus, rapid selection of high-level resistance to beta-lactams.

The aim of this study is to describe the phenotypic and genetic properties of oxacillin-susceptible methicillin-resistant Staphylococcus aureus (OS-MRSA) isolates and their beta-lactam resistant derivatives obtained after selection with oxacillin. A collection of hospital- (HA-) and community-acquired (CA-) MRSA was screened for oxacillin susceptibility. Antibiotic susceptibility testing, population analysis profile (PAP), mecA expression analysis, and whole genome sequencing (WGS) were performed for 60 mecA-positive OS-MRSA isolates.

Adaptive Laboratory Evolution of Resistance to Vancomycin and Daptomycin: Mutation Patterns and Cross-Resistance.

Vancomycin and daptomycin are first-line drugs for the treatment of complicated methicillin-resistant (MRSA) infections, including bacteremia. However, their effectiveness is limited not only by their resistance to each antibiotic but also by their associated resistance to both drugs. It is unknown whether novel lipoglycopeptides can overcome this associated resistance.

Global Expansion of Linezolid-Resistant Coagulase-Negative Staphylococci.

Coagulase-negative staphylococci (CoNS) for a long time were considered avirulent constituents of the human and warm-blooded animal microbiota. However, at present, , , and are recognized as opportunistic pathogens. Although linezolid is not registered for the treatment of CoNS infections, it is widely used off-label, promoting emergence of resistance.

In Vitro Selection of High-Level Beta-Lactam Resistance in Methicillin-Susceptible .

Selective pressure of beta-lactams is thought to be responsible for mutation selection in methicillin-susceptible (MSSA). We used next-generation sequencing to compare the genomes of beta-lactamase-positive (SA0707) and -negative (SA0937) MSSA isolates with their derivatives obtained after selection with oxacillin, ceftaroline, or meropenem. Selection with oxacillin and ceftaroline caused a rapid and significant (6-8 times) increase in the minimum inhibitory concentration (MICs) of oxacillin, penicillin, amoxicillin/clavulanate, and ceftaroline against the derivatives of both isolates, associated with growth impairment.

Comparative genome analysis of global and Russian strains of community-acquired methicillin-resistant Staphylococcus aureus ST22, a 'Gaza clone'.

In this study, we identified the relationship between the genetic lineage of community-acquired methicillin-resistant Staphylococcus aureus (CA-MRSA) sequence type 22 (ST22) from Russia and other regions. Sixty ST22 isolates from Russia were characterised through whole-genome sequencing. To evaluate the phylogenetic relationship of Russian isolates with the global ST22 population, we analysed 1283 genomes obtained from NCBI's GenBank.

Ceftaroline Resistance Selection of Methicillin-Resistant Involves Different Genetic Pathways.

The pathways in the development of ceftaroline resistance of methicillin-resistant (MRSA) isolates belonging to the ST8, ST239, and ST228 were evaluated. Ceftaroline-resistant derivatives were isolated through selection during 40 passages. Ceftaroline MIC measurements and whole-genome sequencing were performed after 5, 20, and 40 passages.

Observational study of nasopharyngeal carriage of Neisseria meningitidis in applicants to a military academy in the Russian Federation.

Objective: To determine the carriage and the serogroup distribution of Neisseria meningitidis in military academy applicants in the Russian Federation.

Design: This was a prospective, observational study of adults aged >18years from a military academy; applicants who had samples taken on arrival (Day 1), and applicants who had samples taken after passing exams (Day 30) and 60days after arrival. N.

Molecular epidemiology and antibiotic resistance of methicillin-resistant Staphylococcus aureus circulating in the Russian Federation.

The aim of this study was to investigate the patterns of antimicrobial resistance and molecular features of methicillin-resistant Staphylococcus aureus (MRSA) isolates in Russia. Isolates recovered from hospital patients (n=480), healthy medical personnel (n=25), and healthy carriers (n=13) were included in the study. Hospital-acquired MRSA (HA-MRSA) demonstrated high resistance to ciprofloxacin, gentamicin, and chloramphenicol (76%-92%), moderate - to tetracycline, erythromycin, clindamycin, and rifampicin (38%-54%), and low - to fusidic acid, co-trimoxazole, mupirocin, and daptomycin (2%-7%).

Surveillance of antimicrobial susceptibility of Enterobacteriaceae pathogens isolated from intensive care units and surgical units in Russia.

A total of 473 strains of Enterobacteriaceae, including Escherichia coli, Klebsiella spp., Proteus spp., Citrobacter spp.