Group B streptococci (GBS; Streptococcus agalactiae) are the leading cause of neonatal invasive diseases and are also important pathogens for adults. Penicillins are the drugs of first choice for the treatment of GBS infections, since GBS have been regarded to be uniformly susceptible to penicillins so far. Here we characterize the first strains of GBS with reduced penicillin susceptibility (PRGBS) identified in Japan. Fourteen PRGBS strains were clinically isolated from the sputa of elderly patients from 1995 to 2005; and the MICs of penicillin, oxacillin, and ceftizoxime ranged from 0.25 to 1 g/ml, 2 to 8 g/ml, and 4 to 128 g/ml, respectively. Moreover, some strains were also insusceptible to ampicillin, cefazolin, cefepime, and cefotaxime. All the PRGBS isolates tested possessed a few amino acid substitutions adjacent to the conserved SSN and KSG motifs (amino acids 402 to 404 and 552 to 554, respectively) of PBP 2X, and the amino acid substitutions could be classified into two types, Q557E and V405A. Western blotting analysis of the 14 clinical isolates with anti-PBP 2X-specific serum suggested that the amount of PBP 2X among the 14 PRGBS isolates was reduced, although the 2 ATCC strains produced a significant amount of PBP 2X. The introduction of PRGBS-derived PBP 2X genes into penicillin-susceptible strains through allelic exchange elevated their penicillin insusceptibility, suggesting that these altered PBP 2X genes are responsible for the penicillin insusceptibility in PRGBS strains. In this study, we characterized for the first time PRGBS strains on a molecular basis, although several reports have so far mentioned the existence of ␤-lactam-insusceptible GBS from a phenotypic standpoint.

Type III group B streptococci (GBS) isolated from Tokyo and Salt Lake City were classified according to the similarity of HindIII and Sse83871 restriction digest patterns (RDPs) of bacterial DNA. The bacteria were clustered into three RDP types, with excellent correlation between subtyping based on the two enzymes. The majority (91%) of invasive isolates obtained from neonates were RDP type III-3. The mean sialic acid content of the III-3 strains was higher than that of other type III strains. Closely related isolates were concordant for expression of the bacterial enzyme C5a-ase, but invasive strains were no more likely to be C5a-ase positive than were strains isolated from the genitourinary tract of pregnant women. These data indicate that a group of genetically related organisms with increased capsule production causes the majority of invasive type III GBS disease. Group B streptococci (GBS) 3) causes most serotype III neonatal sepsis, suggesting the RDP typing. DNA was extracted from GBS suspended in agarose existence of a genetically related subgroup of serotype III GBS gel plugs (InCert; FMC BioProducts, Rockland, ME) according to that are intrinsically more virulent than other serotype III strains the manufacturer's instructions except that mutanolysin and SDS con- [4]. The purpose of these studies was to determine whether taining proteinase K were used for digestion of the bacteria. DNA in invasive serotype III isolates from Salt Lake City, as well as the agarose gel plugs was digested with HindIII, extracted from the more recently isolated clinical isolates from Japan, are also agarose with phenol, and redigested with HindIII. The DNA sample RDP III-3. We also validated the HindIII typing by typing the was then subjected to electrophoresis in a conventional ethidium bromide-agarose gel. The similarity between densitometric RDPs from individual strains was expressed as a Pearson product moment correlation coefficient (PPMCC) and clustered by the unweighted

No abstract

This is the first description of the nosocomial spread of multidrug-resistant PRGBS strains belonging to the genetic lineage ST458.

The plasmid-mediated novel ␤-lactamase CTX-M-64 was first identified in Shigella sonnei strain UIH-1, which exhibited resistance to cefotaxime (MIC, 1,024 g/ml) and ceftazidime (MIC, 32 g/ml). The amino acid sequence of CTX-M-64 showed a chimeric structure of a CTX-M-15-like ␤-lactamase (N-and C-terminal moieties) and a CTX-M-14-like ␤-lactamase (central portion, amino acids 63 to 226), suggesting that it originated by homologous recombination between the corresponding genes. The introduction of a recombinant plasmid carrying bla CTX-M-64 conferred resistance to cefotaxime in Escherichia coli, and the activities of cefotaxime and ceftazidime were restored in the presence of clavulanic acid. Of note, CTX-M-64 production could also confer consistent resistance to ceftazidime, which differs from the majority of CTX-M-type enzymes, which poorly hydrolyze ceftazidime. These results were consistent with the kinetic parameters determined with the purified CTX- Shigellosis remains a public health concern throughout the world and has become an actual threat, particularly in developing countries, where 99% of the estimated 165 million annual episodes occur. Children under 5 years of age have been involved in more than half of the episodes and deaths (14). Shigellosis is more severe in malnourished children and elderly and immunocompromised people. Antibiotic treatment shortens the duration of clinical symptoms and pathogen excretion, prevents disease transmission, and reduces the risk of potential complications (18,27,34). However, empirical therapy with first-line antimicrobial agents, including ampicillin, trimethoprim-sulfamethoxazole, chloramphenicol, nalidixic acid, co-trimoxazole, and tetracycline, has become less effective due to the high prevalence of multidrug-resistant (MDR) clinical isolates among Shigella species (9, 28, 29, 32). For these MDR isolates, the therapeutic options for oral administration are fluoroquinolones for adults and oxyimino-cephalosporins for children.Plasmid-encoded class A extended-spectrum ␤-lactamase (ESBL) production is still uncommon among Shigella species, despite the worldwide spread and prevalence of ESBL-producing clinical isolates belonging to the family Enterobacteriaceae. Four CTX-M-type ␤-lactamases, CTX-M-2, CTX-M-3, CTX-M-14, and CTX-M-15, and several TEM-derived ESBLs have been reported for Shigella sonnei (1,11,15,25). S. sonnei strain UIH-1, characterized in this study, produced a novel CTX-Mtype ␤-lactamase, a hybrid of the CTX-M-15-like ␤-lactamase, which is a new CTX-M-15 variant (GenBank accession no. DQ256091), and the CTX-M-14 ␤-lactamase; and this chimeric enzyme conferred resistance to ceftazidime as well as to cefotaxime and ceftriaxone. MATERIALS AND METHODSClinical isolate. S. sonnei UIH-1 was identified with the API 20E system (bioMérieux) in combination with tests for the utilization of citrate with Christensen's citrate medium (4), sodium acetate, and mucate and by PCR detection of the invE and ipaH genes with specific primer sets (Takara Bio, Shiga, Japan)...

Three strains of cefotaxime (CTX)-resistant Acinetobacter baumannii, FM0209680, FM0300106, and FM0301433, were isolated from transtracheal aspirate cultures of three patients with probable nosocomial infections in a neurosurgery ward in Japan. The CTX MICs for these isolates were greater than 128 g/ml but were drastically reduced in the presence of 4 g of clavulanic acid per ml. These strains were also resistant to ceftriaxone, cefpodoxime, and aztreonam but were susceptible to ceftazidime and imipenem. The profile of resistance to various broad-spectrum ␤-lactams was transferred by conjugation. Strain FM0209680 was not eradicated from case patient 1 by administration of imipenem, ceftazidime, and levofloxacin, even after a 6-month hospitalization period. Strains FM0300106 and FM0301433 were isolated from case patients 2 and 3 during the sixth week following admission, respectively, and then each patient was colonized for 3 weeks. Eradication of FM0300106 was successfully obtained from case patient 2 by imipenem treatment, while administration of imipenem was continued to prevent pneumonia. Prophylactic antimicrobial therapy was discontinued in case patient 3 because of the lack of pneumonic symptoms, and FM0301433 disappeared after the discontinuation of antimicrobial chemotherapy. All three strains carried the bla CTX-M-2 gene, and the appearance of colonies in the growth-inhibitory zones around disks of CTX and aztreonam in double-disk synergy tests suggested inducible ␤-lactamase production in these A. baumannii strains. The ribotyping investigation suggested that all these strains belong to the same clonal lineage. The plasmids harbored by A. baumannii had the same restriction profile as those harbored by Proteus mirabilis strains previously isolated in a urology ward of the Funabashi Medical Center.

In recent years, besides the widespread occurrence of extended-spectrum β-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 bla and bla (n = 15 each), followed by bla (n = 14), bla (n = 10), and bla (n = 5). In 21 K. pneumoniae, 10 bla gene types including bla (n = 4), bla (n = 4), and bla (n = 3) were found. The bla 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 bla-harboring isolates were noted among the H30R/non-Rx lineage (13/19, 68.4%) (p < 0.05). The genetic environment of bla 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.

Since around the 2000s, Escherichia coli (E. coli) resistant to both oxyimino-cephalosporins and fluoroquinolones has remarkably increased worldwide in clinical settings. The kind of E. coli is also identified in patients suffering from communityonset infectious diseases such as urinary tract infections. Moreover, recoveries of multi-drug resistant E. coli from the feces of healthy people have been increasingly documented in recent years, although the actual state remains uncertain. These E. coli isolates usually produce extended-spectrum β-lactamase (ESBL), as well as acquisition of amino acid substitutions in the quinolone-resistance determining regions (QRDRs) of GyrA and/or ParC, together with plasmid-mediated quinolone resistance determinants such as Qnr, AAC(6')-Ib-cr, and QepA. The actual state of ESBL-producing E. coli in hospitalized patients has been carefully investigated in many countries, while that in healthy people still remains uncertain, although high fecal carriage rates of ESBL producers in healthy people have been reported especially in Asian and South American countries. The issues regarding the ESBL producers have become very complicated and chaotic due to rapid increase of both ESBL variants and plasmids mediating ESBL genes, together with the emergence of various "epidemic strains" or "international clones" of E. coli and Klebsiella pneumoniae harboring transferable-plasmids carrying multiple antimicrobial resistance genes. Thus, the current state of ESBL producers outside hospital settings was overviewed together with the relation among those recovered from livestock, foods, pets, environments and wildlife from the viewpoint of molecular epidemiology. This mini review may contribute to better understanding about ESBL producers among people who are not familiar with the antimicrobial resistance (AMR) threatening rising globally.