Predominance of methicillin-resistant Staphylococcus aureus SCCmec type II-CC5 and SCCmec type IV-CC1/CC8 among companion animal clinical isolates in Japan: Findings from phylogenetic comparison with human clinical isolates.

OBJECTIVES: To characterise the genotypic profiles of methicillin-resistant Staphylococcus aureus (MRSA) clinical isolates from companion animals and to investigate their association with those from humans in Japan. METHODS: Non-duplicated MRSA clinical isolates recovered between July 2016 and January 2018 were analysed. The MRSA isolates were typed by polymerase chain reaction (PCR)-based open reading frame (ORF) typing (POT) scores, SCCmec types, multilocus sequence typing, and virulence gene profiles. Phylogenetic comparison of those isolates with previously described human isolates was performed. RESULTS: Among 56 MRSA isolates (33 cats, 20 dogs and three rabbits), 26 isolates with a POT1 score of 93, SCCmec type II mostly belonged to CC5, including ST5. Twenty-six isolates with a POT1 score of 106, SCCmec type IV showed diversity of STs: 15 isolates belonged to CC8, mainly including ST8, and 11 isolates belonged to CC1, including ST1 and newly identified STs 4768, 4775, and 4779. Two cat isolates were ST8-SCCmec type IV possessing pvl/ACME-arcA, presumed to be the hypervirulent community-associated MRSA (CA-MRSA) clone USA300. Notably, all three rabbit isolates belonged to ST4768. The POT1 score 106 CA-MRSA isolates from animals and humans were divided into two large clusters of CC1 and CC8, where host species-specific sub-clusters were not identified within each cluster. A large cluster of POT1 score 93 healthcare-associated MRSA (HA-MRSA) isolates from animals and humans consisted of sub-clusters formed exclusively by the vast majority of human isolates and those formed by animal and human isolates. CONCLUSION: Companion animals could be potential reservoirs and vehicles for the transmission of CA-MRSA to humans, and could transmit companion animal-adaptive HA-MRSA lineages to humans as their second reservoirs.

Population-level transition of capsular polysaccharide types among sequence type 1 group B Streptococcus isolates with reduced penicillin susceptibility during a long-term hospital epidemic.

Over a 35-month period, group B Streptococcus isolates with reduced penicillin susceptibility (PRGBS) were detected from elderly patients at a regional hospital in Japan, accompanying population-level transition of PRGBS serotypes. The genetic relatedness of 77 non-duplicate PRGBS from 73 patients was analysed. Serotype III PRGBS predominated (16 serotype III/1 serotype Ib) in the first 9 months (period I), then 3 serotype Ib isolates appeared transiently for the next 3 months (period II), which was replaced predominantly by serotype Ia (20 serotype Ia/1 serotype III/1 non-typeable) for 9 months (period III). In the last 14 months (period IV), besides 25 serotype Ia isolates, 10 serotype III were also identified. Serotypes III and Ia isolates, belonging to ST1, shared G329V, G398A, V405A and G429D substitutions in penicillin-binding protein 2X. Of three strains subjected to whole-genome sequencing, serotype III strain SU12 (period I) had a higher degree of genomic similarity with serotype Ia strain SU97 (period III) than serotype Ib strain SU67 (period II) based on average nucleotide identity and single nucleotide polymorphisms. Analysis of the cps gene clusters and the upstream and downstream flanking sequences revealed that disruption of the hyaluronidase gene located upstream of cpsY by insertion of IS1548 was found in strain SU12, whereas ΔISSag8 was inserted between tRNA-Arg and rpsA genes located downstream of cpsL in strain SU97. Interestingly, most serotype III PRGBS re-emerging in period IV had this tRNA-Arg-ΔISSag8-rpsA region. Capsular switching and nosocomial transmission may possibly contribute to population-level serotype replacement among ST1 PRGBS isolates.

Prevalence of ESBL/AmpC genes and specific clones among the third-generation cephalosporin-resistant Enterobacteriaceae from canine and feline clinical specimens in Japan.

In recent years, besides the widespread occurrence of extended-spectrum ß-lactamase (ESBL)- and/or plasmid-mediated AmpC (pAmpC)-producing Enterobacteriaceae in both healthcare and community settings of humans, the third-generation cephalosporin (3GC)-resistant microbes have also been reported from companion animals worldwide. Here, we characterized ESBL- and/or pAmpC-producing Enterobacteriaceae clinical isolates from companion animals. Among the 487 clinical isolates mainly from urine of dogs and cats between May and September 2016, 104 non-repetitive isolates were resistant to the 3GC, and they consisted of 81 of 381 (21.3%) Escherichia coli, 21 of 50 (42.0%) Klebsiella pneumoniae, and 2 of 56 (3.6%) Proteus mirabilis isolates. In the 81 E. coli, the predominant bla genes were blaCTX-M-27 and blaCMY-2 (n = 15 each), followed by blaCTX-M-15 (n = 14), blaCTX-M-14 (n = 10), and blaCTX-M-55 (n = 5). In 21 K. pneumoniae, 10 bla gene types including blaCTX-M-15 (n = 4), blaCTX-M-2 (n = 4), and blaCTX-M-14 (n = 3) were found. The blaCTX-M-2 was identified in 2 P. mirabilis. Twenty-four of the 42 E. coli belonging to phylogroup B2 were O25b-ST131 clone, mostly associated with uropathogenic E. coli pathotype, and 22 isolates of this clone were identified as specific H30R subclone. High prevalence of the blaCTX-M-27-harboring isolates were noted among the H30R/non-Rx lineage (13/19, 68.4%) (p <  0.05). The genetic environment of blaCTX-M-27 of most isolates of this lineage was identical to that of human isolates, but unique flanking genetic structures were also identified. Newly emerging virulent lineage B2-non-O25b-ST1193 was also confirmed in 5 isolates. The fosA3 and/or armA genes were detected in E. coli and K. pneumoniae isolates. These data suggest that companion animals serve as a potential reservoir of antimicrobial resistant E. coli and K. pneumoniae. This also has considerable veterinary importance, since urinary tract infections are an important disease causing therapeutic challenges worldwide.