Molecular epidemiology of carbapenemase-producing Enterobacteriaceae in a primary care hospital in Japan, 2010–2013

Emergence of extensive drug resistance and high prevalence of multidrug resistance among clinical Proteus mirabilis isolates in Egypt

BACKGROUND

Proteus mirabilis is an opportunistic pathogen that has been held responsible for numerous nosocomial and community-acquired infections which are difficult to be controlled because of its diverse antimicrobial resistance mechanisms.

METHODS

Antimicrobial susceptibility patterns of P. mirabilis isolates collected from different clinical sources in Mansoura University Hospitals, Egypt was determined. Moreover, the underlying resistance mechanisms and genetic relatedness between isolates were investigated.

RESULTS

Antimicrobial susceptibility testing indicated elevated levels of resistance to different classes of antimicrobials among the tested P. mirabilis clinical isolates (n = 66). ERIC-PCR showed great diversity among the tested isolates. Six isolates (9.1%) were XDR while all the remaining isolates were MDR. ESBLs and AmpCs were detected in 57.6% and 21.2% of the isolates, respectively, where blaTEM, blaSHV, blaCTX-M, blaCIT-M and blaAmpC were detected. Carbapenemases and MBLs were detected in 10.6 and 9.1% of the isolates, respectively, where blaOXA-48 and blaNDM-1 genes were detected. Quinolone resistant isolates (75.8%) harbored acc(6')-Ib-cr, qnrD, qnrA, and qnrS genes. Resistance to aminoglycosides, trimethoprim-sulfamethoxazole and chloramphenicol exceeded 80%. Fosfomycin was the most active drug against the tested isolates as only 22.7% were resistant. Class I or II integrons were detected in 86.4% of the isolates. Among class I integron positive isolates, four different gene cassette arrays (dfrA17- aadA5, aadB-aadA2, aadA2-lnuF, and dfrA14-arr-3-blaOXA-10-aadA15) and two gene cassettes (dfrA7 and aadA1) were detected. While class II integron positive isolates carried four different gene cassette arrays (dfrA1-sat1-aadA1, estXVr-sat2-aadA1, lnuF- dfrA1-aadA1, and dfrA1-sat2).

CONCLUSION

P. Mirabilis ability to acquire resistance determinants via integrons may be held responsible for the elevated rates of antimicrobial resistance and emergence of XDR or even PDR strains limiting the available therapeutic options for management of infections caused by those strains.

Clinical and genomic characteristics of IMP-producing Enterobacter cloacae complex and Klebsiella pneumoniae

Carbapenemase-producing Enterobacterales (CPEs) are one of the top priority antimicrobial-resistant pathogens. Among CPEs, those producing acquired metallo-β-lactamases (MBLs) are considered particularly problematic as few agents are active against them. Imipenemase (IMP) is the most frequently encountered acquired MBL in Japan, but comprehensive assessment of clinical and microbiological features of IMP-producing Enterobacterales infection remains scarce. Here, we retrospectively evaluated 62 patients who were hospitalized at a university hospital in Japan and had IMP-producing Enterobacterales from a clinical culture. The isolates were either Enterobacter cloacae complex or Klebsiella pneumoniae, and most of them were isolated from sputum. The majority of K. pneumoniae, but not E. cloacae complex isolates, were susceptible to aztreonam. Sequence type (ST) 78 and ST517 were prevalent for E. cloacae complex and K. pneumoniae, respectively, and all isolates carried blaIMP-1. Twenty-four of the patients were deemed infected with IMP-producing Enterobacterales. Among the infected patients, therapy varied and largely consisted of conventional β-lactam agents, fluoroquinolones, or combinations. Three (13%), five (21%), and nine (38%) of them died by days 14, 30, and 90, respectively. While incremental mortality over 90 days was observed in association with underlying comorbidities, active conventional treatment options were available for most patients with IMP-producing Enterobacterales infections, distinguishing them from more multidrug-resistant CPE infections associated with globally common MBLs, such as New Delhi metallo-β-lactamase (NDM) and Verona integron-encoded metallo-β-lactamase (VIM).

Antibiotic resistance and virulence profiles of Proteus mirabilis isolated from broiler chickens at abattoir in South Africa

BACKGROUND

Proteus mirabilis has been identified as an important zoonotic pathogen, causing several illnesses such as diarrhoea, keratitis and urinary tract infections.

OBJECTIVE

This study assessed the prevalence of P. mirabilis in broiler chickens, its antibiotic resistance (AR) patterns, ESBL-producing P. mirabilis and the presence of virulence genes.

METHODS

A total of 26 isolates were confirmed as P. mirabilis from 480 pooled broiler chicken faecal samples by polymerase chain reaction (PCR). The disk diffusion method was used to evaluate the antibacterial susceptibility test, while nine virulence genes and 26 AR genes were also screened by PCR.

RESULTS

All 26 P. mirabilis isolates harboured the ireA (siderophore receptors), ptA, and zapA (proteases), ucaA, pmfA, atfA, and mrpA (fimbriae), hlyA and hpmA (haemolysins) virulence genes. The P. mirabilis isolates were resistant to ciprofloxacin (62%) and levofloxacin (54%), while 8 (30.7%) of the isolates were classified as multidrug resistant (MDR). PCR analysis identified the blaCTX-M gene (62%), blaTEM (58%) and blaCTX-M-2 (38%). Further screening for AMR genes identified mcr-1, cat1, cat2, qnrA, qnrD and mecA, 12%, 19%, 12%, 54%, 27% and 8%, respectively for P. mirabilis isolates. The prevalence of the integron integrase intI1 and intI2 genes was 43% and 4%, respectively.

CONCLUSIONS

The rise of ciprofloxacin and levofloxacin resistance, as well as MDR strains, is a public health threat that points to a challenge in the treatment of infections caused by these zoonotic bacteria. Furthermore, because ESBL-producing P. mirabilis has the potential to spread to humans, the presence of blaCTX -M -producing P. mirabilis in broilers should be kept under control. This is the first study undertaken to isolate P. mirabilis from chicken faecal samples and investigate its antibiotic resistance status as well as virulence profiles in South Africa.

Clinical and Microbiological Characteristics of Bacteremia Caused by Carbapenemase-producing Enterobacterales in Minami Ibaraki Area, Japan

Although recent propagation of carbapenemase-producing Enterobacterales (CPE) has become a problem worldwide, the picture of CPE infection in Japan has not fully been elucidated. In this study, we examined clinical and microbiological characteristics of invasive CPE infection occurring at 8 hospitals in Minami Ibaraki Area between July 2001 to June 2017. Of 7294 Enterobacterales strains isolated from independent cases of bacteremia and/or meningitis, 10 (0.14%) were CPE (8 Enterobacter cloacae-complex, 1 Escherichia coli, and 1 Edwardsiella tarda）, all of which had the blaIMP-1 gene and susceptible to gentamicin and trimethoprim/sulfamethoxazole. These strains were isolated from 7 adult and 2 infant bacteremia (1 infant patient developed CPE bacteremia twice) after 2007. The most common portal of entry was intravenous catheters. All of the adult patients were recovered, while the infant patients eventually died. Genomic analyses showed that the 8 E. cloacae-complex strains were classified into 5 groups, each of which was exclusively detected in specific facilities at intervals of up to 3 years, suggesting persistent colonization in the facilities. This study showed that invasive CPE infection in the area was rare, caused by IMP-1-type CPE having susceptibility to various antibiotics, and nonfatal among adult patients.

Uropathogenic Escherichia coli endeavors: an insight into the characteristic features, resistance mechanism, and treatment choice

Uropathogenic Escherichia coli (UPEC) are the strains diverted from the intestinal status and account mainly for uropathogenicity. This pathotype has gained specifications in structure and virulence to turn into a competent uropathogenic organism. Biofilm formation and antibiotic resistance play an important role in the organism's persistence in the urinary tract. Increased consumption of carbapenem prescribed for multidrug-resistant (MDR) and Extended-spectrum-beta lactamase (ESBL)-producing UPECs, has added to the expansion of resistance. The World Health Organization (WHO) and Centre for Disease Control (CDC) placed the Carbapenem-resistant Enterobacteriaceae (CRE) on their treatment priority lists. Understanding both patterns of pathogenicity, and multiple drug resistance may provide guidance for the rational use of anti-bacterial agents in the clinic. Developing an effective vaccine, adherence-inhibiting compounds, cranberry juice, and probiotics are non-antibiotical approaches proposed for the treatment of drug-resistant UTIs. We aimed to review the distinguishing characteristics, current therapeutic options and promising non-antibiotical approaches against ESBL-producing and CRE UPECs.

Structural insights into the substrate specificity of IMP-6 and IMP-1 metallo-β-lactamases

IMP-type metallo-β-lactamases confer resistance to carbapenems and a broad spectrum of β-lactam antibiotics. IMP-6 and IMP-1 differ by only a point mutation: Ser262 in IMP-1 and Gly262 in IMP-6. The kcat/Km values of IMP-1 for imipenem and meropenem are nearly identical; however, for IMP-6, the kcat/Km for meropenem is 7-fold that for imipenem. In clinical practice, this may result in an ineffective therapeutic regimen and, consequently, in treatment failure. Here, we report the crystal structures of IMP-6 and IMP-1 with the same space group and similar cell constants at resolutions of 1.70 and 1.94 Å, respectively. The overall structures of IMP-6 and IMP-1 are similar. However, the loop region (residues 60-66), which participates in substrate binding, is more flexible in IMP-6 than in IMP-1. This difference in flexibility determines the substrate specificity of IMP-type metallo-β-lactamases for imipenem and meropenem. The amino acid at position 262 alters the mobility of His263; this affects the flexibility of the loop via a hydrogen bond with Pro68, which plays the role of a hinge in IMP-type metallo-β-lactamases. The substitution of Pro68 with a glycine elicited an increase in the Km of IMP-6 for imipenem, whereas the affinity for meropenem remained unchanged.

Detection of Enterobacter cloacae complex strain with a blaNDM-1-harboring plasmid from an elderly resident at a long-term care facility in Okayama, Japan

Amidst the global spread of antimicrobial resistance, New Delhi metallo-β-lactamase (NDM)-type carbapenemase-producing Enterobacterales (CPE) remain uncommon in Japan, and the detection of such highly drug-resistant organisms is limited to inbound cases. There is little evidence regarding the prevalence of NDM β-lactamase gene (bla_NDM)-harboring CPE in the domestic community, especially in the provincial cities of Japan. Herein, we report the isolation of a bla_NDM-1-harboring plasmid in Enterobacter cloacae complex strain isolated from an elderly woman without a history of traveling abroad who had resided in a long-term care facility in Okayama, Japan. The multidrug-resistant bla_NDM-harboring CPE isolate was detected in a stool sample of the patient during routine screening at admission. We performed whole-genome sequencing analysis of the isolate using MiSeq (Illumina) and MinION (Oxford Nanopore Technologies) platforms. The isolate was identified as sequence type 171, which has predominantly been reported in the United States and China. The bla_NDM-1 gene was encoded on the 46,161 bp IncX3 plasmid, with sequence similarity to plasmids of similar size isolated from individuals in China. Collectively, the genomic data suggest that an imported CPE isolate may have spread among healthy individuals in the regional area of Japan.

Clinical characteristics and antimicrobial susceptibility of Klebsiella pneumoniae, Klebsiella variicola and Klebsiella quasipneumoniae isolated from human urine in Japan

Introduction. The three Klebsiella species K. pneumoniae, K. variicola and K. quasipneumoniae are difficult to distinguish, owing to their similar biochemical properties, and are often confused in medical practice.Gap statement. There is a scarcity of data comparing the clinical characteristics and antimicrobial susceptibility of K. pneumoniae, K. variicola and K. quasipneumoniae. We believe that knowledge of the characteristics of each species will help in their better identification. Further, knowing the antimicrobial susceptibility of the species will help physicians in prescribing an effective treatment course for Klebsiella infections.Aim. This study aimed to determine the clinical characteristics and antimicrobial resistance of K. pneumoniae, K. variicola and K. quasipneumoniae isolated from human urine samples.Methodology. This study included 125 K. pneumoniae strains isolated from human urine samples. Multiplex polymerase chain reaction was performed to identify K. pneumoniae, K. variicola and K. quasipneumoniae. We retrospectively investigated the patient background, complications of bacteraemia, antimicrobial susceptibility and extended-spectrum β-lactamase (ESBL).Results. We identified 84 (67.2 %), 31 (24.8 %) and 10 strains (8 .0%) of K. pneumoniae, K. variicola and K. quasipneumoniae, respectively. There was no difference in patient background and frequency of bacteraemia complications among these species. K. pneumoniae was significantly less susceptible than K. variicola to ampicillin/sulbactam (P=0.03) and piperacillin (P<0.01). Furthermore, K. pneumoniae (79.8 %) was less susceptible to trimethoprim/sulfamethoxazole than K. variicola (96.8 %) and K. quasipneumoniae (100 %). There were nine ESBL-producing strains (7.2 %), all of which were K. pneumoniae.Conclusion. There was no difference in patient background and frequency of bacteraemia complications between K. pneumoniae, K. variicola and K. quasipneumoniae isolated from urine. The three Klebsiella species showed a varying extent of antimicrobial susceptibility and ESBL production, and accurate identification is needed to understand the epidemiology of these species.

The Role of nmcR, ampR, and ampD in the Regulation of the Class A Carbapenemase NmcA in Enterobacter ludwigii

Various carbapenemases have been identified in the Enterobacteriaceae. However, the induction and corresponding regulator genes of carbapenemase NmcA has rarely been detected in the Enterobacter cloacae complex (ECC). The NmcA-positive isolate ECC NR1491 was first detected in Japan in 2013. It was characterized and its induction system elucidated by evaluating its associated regulator genes nmcR, ampD, and ampR. The isolate was highly resistant to all β-lactams except for third generation cephalosporins (3GC). Whole-genome analysis revealed that bla_NmcA was located on a novel 29-kb putatively mobile element called EludIMEX-1 inserted into the chromosome. The inducibility of β-lactamase activity by various agents was evaluated. Cefoxitin was confirmed as a strong concentration-independent β-lactamase inducer. In contrast, carbapenems induced β-lactamase in a concentration-dependent manner. All selected 3GC-mutants harboring substitutions on ampD (as ampR and nmcR were unchanged) were highly resistant to 3GC. The ampD mutant strain NR3901 presented with a 700 × increase in β-lactamase activity with or without induction. Similar upregulation was also observed for ampC and nmcA. NR1491 (pKU412) was obtained by transforming the ampR mutant (135Asn) clone plasmid whose expression increased by ∼100×. Like NR3901, it was highly resistant to 3GC. Overexpression of ampC, rather than nmcA, may have accounted for the higher MIC in NR1491. The ampR mutant repressed nmcA despite induction and it remains unclear how it stimulates nmcA transcription via induction. Future experiments should analyze the roles of nmcR mutant strains.

The Antimicrobial Resistance Characteristics of Imipenem-Non-Susceptible, Imipenemase-6-Producing Escherichia coli

Imipenemase-6 (IMP-6) type carbapenemase-producing Enterobacteriaceae is regarded as dangerous due to its unique lack of antimicrobial susceptibility. It is resistant to meropenem (MEPM) but susceptible to imipenem (IPM). In addition to carbapenemase, outer membrane porins and efflux pumps also play roles in carbapenem resistance by reducing the antimicrobial concentration inside cells. Extended-spectrum β-lactamase (ESBL) is transmitted with IMP-6 by the plasmid and broadens the spectrum of antimicrobial resistance. We collected 42 strains of IMP-6-producing Escherichia coli and conducted a molecular analysis of carbapenemase, ESBL, porin, efflux, and epidemiological characteristics using plasmid replicon typing. Among the 42 isolates, 21 strains were susceptible to IPM (50.0%) and 1 (2.4%) to MEPM. Seventeen strains (40.5%) co-produced CTX-M-2 type ESBL. We found that the relative expression of ompC and ompF significantly correlated with the MIC of IPM (p = 0.01 and p = 0.03, respectively). Sixty-eight% of CTX-M-2-non-producing strains had IncI1, which was significantly different from CTX-M-2-producing strains (p < 0.001). In conclusion, 50.0% of our IMP-6-producing strains were non-susceptible to IPM, which is different from the typical pattern and can be attributed to decreased porin expression. Further studies investigating other types of carbapenemase are warranted.

Possible Dissemination of Escherichia coli Sequence Type 410 Closely Related to B4/H24RxC in Ghana

Extra-intestinal pathogenic Escherichia coli (ExPEC) is one of the world’s leading causes of bloodstream infections with high mortality. Sequence type 410 (ST410) is an emerging ExPEC clone resistant to a wide range of antibiotics. In this study, we investigated the epidemiology of 21 ST410 E. coli isolates from two Ghanaian hospitals. We also investigated the isolates within a global context to provide further insight into the dissemination of this highly pathogenic clone. A phylogenetic tree of the 21 isolate genomes, along with 102 others from global collection, was constructed representing the ensuing clades and sub-clades of the ST: A/H53, B2/H24R, B3/H24Rx, and B4/H24RxC. The carbapenem-resistant sub-clade B4/H24RxC is reported to have emerged in the early 2000s when ST410 acquired an IncX3 plasmid carrying a bla_OXA–181 carbapenemase gene, and a second carbapenemase gene, bla_NDM–5, on a conserved IncFII plasmid in 2014. We identified, in this study, one bla_OXA–181–carrying isolate belonging to B4/H24RxC sub-lineage and one carrying bla_NDM–1 belonging to sub-lineage B3/H24Rx. The bla_OXA–181 gene was found on a 51kb IncX3 plasmid; pEc1079_3. The majority (12/21) of our Ghanaian isolates were clustered with international strains described by previous authors as closely related strains to B4/H24RxC. Six others were clustered among the ESBL-associated sub-lineage B3/H24Rx and three with the globally disseminated sub-lineage B4/H24RxC. The results show that this highly pathogenic clone is disseminated in Ghana and, given its ability to transmit between hosts, it poses a serious threat and should be monitored closely.

Klebsiella oxytoca Complex: Update on Taxonomy, Antimicrobial Resistance, and Virulence

Klebsiella oxytoca is actually a complex of nine species-Klebsiella grimontii, Klebsiella huaxiensis, Klebsiella michiganensis, K. oxytoca, Klebsiella pasteurii, Klebsiella spallanzanii, and three unnamed novel species. Phenotypic tests can assign isolates to the complex, but precise species identification requires genome-based analysis. The K. oxytoca complex is a human commensal but also an opportunistic pathogen causing various infections, such as antibiotic-associated hemorrhagic colitis (AAHC), urinary tract infection, and bacteremia, and has caused outbreaks. Production of the cytotoxins tilivalline and tilimycin lead to AAHC, while many virulence factors seen in Klebsiella pneumoniae, such as capsular polysaccharides and fimbriae, have been found in the complex; however, their association with pathogenicity remains unclear. Among the 5,724 K. oxytoca clinical isolates in the SENTRY surveillance system, the rates of nonsusceptibility to carbapenems, ceftriaxone, ciprofloxacin, colistin, and tigecycline were 1.8%, 12.5%, 7.1%, 0.8%, and 0.1%, respectively. Resistance to carbapenems is increasing alarmingly. In addition to the intrinsic bla_OXY, many genes encoding β-lactamases with varying spectra of hydrolysis, including extended-spectrum β-lactamases, such as a few CTX-M variants and several TEM and SHV variants, have been found. bla_KPC-2 is the most common carbapenemase gene found in the complex and is mainly seen on IncN or IncF plasmids. Due to the ability to acquire antimicrobial resistance and the carriage of multiple virulence genes, the K. oxytoca complex has the potential to become a major threat to human health.

The surveillance of colistin resistance and mobilized colistin resistance genes in multidrug-resistant Enterobacteriaceae isolated in Japan

BACKGROUND

The plasmid-mediated bacterial colistin-resistant gene, mcr, is of global concern in clinical healthcare. However, there are few reports of surveillance for mcr in Japan. The aim of this study was to assess the prevalence of colistin resistance by identifying nine mcr genes in extended-spectrum beta-lactamase (ESBL)-producing Enterobacteriaceae and carbapenem-resistant Enterobacteriaceae (CRE) isolates in Japan.

METHODS

A total of 273 ESBL and CRE clinical isolates were collected from patients in five tertiary hospitals from August 2016 to March 2017. Minimum inhibitory concentration (MIC) of colistin was measured using the microdilution method. Polymerase chain reaction (PCR) was performed to detect mcr-1 to mcr-9 genes in all strains. Whole-genome sequencing (WGS) analysis was conducted for any mcr-genes identified that had not been previously reported in patients from Japan.

RESULTS

The rate of colistin resistance was 7.7% in all strains, with a higher rate in the CRE strains than in the ESBL-producing strains (20.4% versus 1.1%). The mcr-5 and mcr-9 gene were detected in one ESBL-producing Escherichia coli strain (1/273, 0.37%) and three CRE strains (3/273, 1.1%), respectively. As the ESBL-producing E. coli strain was the first clinical strain with mcr-5 in Japan, WGS analysis was performed for the strain. The sequence type of the mcr-5-positive strain was ST1642 and it carried two distinct plasmids, ESBL gene-carrying pN-ES-6-1, and mcr-5.1-carrying pN-ES-6-2.

CONCLUSIONS

The results of this study showed that the frequency of colistin resistance and mcr-positive strains is not high in Japan. As the MIC for colistin was low in the mcr-5.1 and mcr-9 gene-positive strain, continuous monitoring of mcr genes is necessary.

In vitro effectiveness of biapenem against IMP-producing Enterobacteriaceae

The options available for treating infections with carbapenemase-producing Enterobacteriaceae (CPE) are limited; with the increasing threat of these infections, new treatments are urgently needed. Biapenem (BIPM) is a carbapenem, and limited data confirming its in vitro killing effect against CPE are available. In this study, we examined the minimum inhibitory concentrations (MICs) and minimum bactericidal concentrations (MBCs) of BIPM for 14 IMP-1-producing Enterobacteriaceae strains isolated from the Okayama region in Japan. The MICs against almost all the isolates were lower than 0.5 µg ml^-1, indicating susceptibility to BIPM, while approximately half of the isolates were confirmed to be bacteriostatic to BIPM. However, initial killing to a 99.9 % reduction was observed in seven out of eight strains in a time-kill assay. Despite the small data set, we concluded that the in vitro efficacy of BIPM suggests that the drug could be a new therapeutic option against infection with IMP-producing CPE.

Genomic Characterization of ESBL- and Carbapenemase-Positive Enterobacteriaceae Co-harboring mcr-9 in Japan

Worldwide spread of Enterobacteriaceae resistant to colistin, a polypeptide antibacterial drug for last-resort treatment of carbapenemase-producing Enterobacteriaceae (CPE) infections, is concerning. This study aimed to elucidate colistin MICs and molecular characteristics of mcr-1 to mcr-9 of ESBL-producing Escherichia coli (ESBL-Ec) and CPE in Japan and clarify the genomic structure of strains harboring mcr genes (especially mcr-9). This study included 168 ESBL-Ec and 126 CPE strains isolated at Japanese medical facilities. Colistin susceptibility testing and multiplex PCR targeting mcr-1 to mcr-9 were performed for all strains with S1-nuclease pulsed-field gel electrophoresis, Southern blot hybridization, and whole-genome sequencing (WGS) with hybrid assembly performed for mcr gene-carrying strains. Two CPE strains showed a MIC ≥ 4 μg/ml in colistin susceptibility testing, with no known resistance mechanism detected. However, PCR conducted on all target strains detected three mcr-9-carrying strains showing colistin susceptibility. The bla_CTX–M–62-positive E. coli THUN648 strain simultaneously carried bla_CTX–M–62 and mcr-9 on a 275-kbp plasmid. Besides, bla_IMP–6 + bla_CTX–M–2-positive Klebsiella pneumoniae THUN262 and bla_GES–24-positive Enterobacter kobei THUN627 had mcr-9 encoded on the chromosome. Only THUN627 encoded qseB/C, which is suggested to be a regulatory gene for mcr-9, downstream of mcr-9. However, this strain showed no increased expression of these genes in mRNA quantitative analysis under colistin exposure. Colistin MICs of ESBL-Ec and CPE in Japan were all below 2 μg/ml, which is below the epidemiological cutoff (ECOFF) value (https://eucast.org/) or clinical breakpoint (CB) (CLSI M100-S30) reported for colistin, indicating neither “microbiological” nor “clinical” resistance. Several colistin-susceptible Enterobacteriaceae carrying silent mcr-9 encoded on plasmids and chromosomes have already spread worldwide along with other antimicrobial resistance genes. However, the mechanism of colistin resistance by mcr-9 remains unclear.

Identification and infection control of carbapenem-resistant Enterobacterales in intensive care units

Infections with multidrug-resistant organisms among patients in intensive care units (ICUs) are associated with high mortality. Among multidrug-resistant organisms, carbapenem-resistant Enterobacterales (CRE) harbor important pathogens for healthcare-associated infections, including pneumonia, bacteremia, and urinary tract infections. Risk factors for CRE colonization include underlying comorbid conditions, prior antibiotics exposure, prior use of healthcare facilities, device use, and longer ICU stay. The mortality rate due to invasive CRE infection is 22%–49%, and CRE colonization is associated with an approximately 10-fold increased risk of CRE infection. Infection control measures include hand hygiene, contact precautions, minimizing the use of devices, and environmental control. Additionally, implementing active surveillance of CRE carriage should be considered in ICU settings.

Evaluation of Disk carbapenemase test using improved disks for rapid detection and differentiation of clinical isolates of carbapenemase-producing Enterobacterales

OBJECTIVES

Rapid detection of carbapenemase-producing Enterobacterales (CPE) is important to control spread of the resistance. We previously reported that imipenem disks prepared from injectable imipenem-cilastatin could rapidly detect KPC- and NDM-type carbapenemases. In the present study, we evaluated performance of disks of IPM and combined disks of imipenem-tazobactam and imipenem-EDTA, which were prepared from powders of imipenem and inhibitors.

METHODS

Isolates of Enterobacterales were recovered from specimens of patients at a tertiary care hospital in Korea during January 2017 and March 2018. Routine CPE detection was performed by the CPE surveillance personnel whereas evaluation of the Disk carbapenemase test (DCT) was performed by the other personnel without knowing the results of surveillance. The DCT was carried out by pressing disks on to colonies and rehydrating in Petri plates and observing color change.

RESULTS

The DCT differentiated 688 of 694 (sensitivity 99.1%) carbapenemase-producing isolates in 2.5-20 min: 630 with KPC, 51 with NDM, three with IMP, one with VIM, two with KPC and IMP, and one with NDM and OXA-181. The DCT failed to detect six OXA- 48-like enzyme-producing isolates, but the modified method using 96-well flat-bottom microplates with mineral oil cover detected all 29 OXA-48-like enzyme-producing isolates in 20-120 min. The DCT was negative for all 440 ertapenem-nonsusceptible, carbapenemase gene-negative isolates (specificity 100%).

CONCLUSION

The procedure of DCT is simple and can differentiate isolates of Enterobacterales with KPC-, NDM-, IMP- and VIM-type carbapenemases rapidly, and the modified DCT can detect isolates with OXA-48-like enzymes rapidly.

Evaluation of MBT STAR-Cepha and MBT STAR-Carba kits for the detection of extended-spectrum β-lactamases and carbapenemase producing microorganisms using matrix-assisted laser desorption/ionization time-of-flight mass spectrometry

Rapid and simple detection of extended-spectrum β-lactamase (ESBL) and carbapenemase is essential for antimicrobial treatment and infection control. Recently, matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS)-based MBT STAR-Cepha and MBT STAR-Carba kits have been developed with simplified MBT STAR-BL operations. However, the utility of these kits has not been fully examined in clinical microbiology laboratories. In this study, we evaluated the utility of MALDI-TOF MS-based MBT STAR-Cepha and MBT STAR-Carba kits to detect ESBL and carbapenemase-producing bacteria, and compared it with the conventional broth microdilution test and PCR amplification assay. We found that the MBT STAR-Cepha kit efficiently distinguished resistant strains of third-generation cephalosporin susceptibility phenotypes and non-SHV-type ESBL producers. In the receiver operating characteristic analysis, the area under the receiver operating characteristic curve (AUC) for detecting third-generation cephalosporin resistance using the MBT STAR-Cepha kit was 0.97-1.00, but the AUC for detecting ESBL producers was 0.64. In addition, we showed that the MBT STAR-Carba kit enabled the accurate detection of antimicrobial resistance by IMP-type carbapenemase producers. The AUC for detecting carbapenemase producers was 1.00. The results suggested that the target bacterial strains, antimicrobial susceptibility phenotypes, and resistance genes were important for the utility of the MALDI-TOF MS-based MBT STAR-Cepha and MBT STAR-Carba kits in bacterial routine diagnostics.

Evaluation of the detection ability of uropathogen morphology and vaginal contamination by the Atellica UAS800 automated urine microscopy analyzer and its effectiveness

Background

To help combat the worldwide spread of multidrug‐resistant Enterobacterales, which are responsible for many causes of urinary tract infection (UTI), we evaluated the ability of the Atellica UAS800 automated microscopy system, the only one offering the capability of bacterial morphological differentiation, to determine its effectiveness.

Methods

We examined 118 outpatient spot urine samples in which pyuria and bacteriuria were observed using flow cytometry (training set: 81; cross‐validation set: 37). The ability of the Atellica UAS800 to differentiate between bacilli and cocci was verified. To improve its ability, multiple logistic regression analysis was used to construct a prediction formula.

Results

This instrument's detection sensitivity was 106 CFU/ml, and reproducibility in that range was good, but data reliability for the number of cocci was low. Multiple logistic regression analysis with each explanatory variable (14 items from the Atellica UAS800, age and sex) showed the best prediction formula for discrimination of uropathogen morphology was a model with 5 explanatory variables: number of bacilli (p < 0.001), squamous epithelial cells (p = 0.004), age (p = 0.039), number of cocci (p = 0.107), and erythrocytes (p = 0.111). For a predicted cutoff value of 0.449, sensitivity was 0.879 and specificity was 0.854. In the cross‐validation set, sensitivity was 0.813 and specificity was 0.857.

Conclusions

The Atellica UAS800 could detect squamous epithelial cells, an indicator of vaginal contamination, with high sensitivity, which further improved performance. Simultaneous use of this probability prediction formula with urinalysis results may facilitate real‐time prediction of uropathogens and vaginal contamination, thus providing helpful information for empiric therapy.

Geographical distribution of Enterobacterales with a carbapenemase IMP-6 phenotype and its association with antimicrobial use: An analysis using comprehensive national surveillance data on antimicrobial resistance

Enterobacterales resistant to carbapenems, a class of last-resort antimicrobials, are ranked as an “urgent” and “critical” public health hazard by CDC and WHO. IMP-type carbapenemase-containing Enterobacterales are endemic in Japan, and bla_IMP-6 is one of the notable carbapenemase genes responsible for the resistance. The gene is plasmid-encoded and confers resistance to meropenem, but not to imipenem. Therefore, IMP-6-producing Enterobacterales isolates are occasionally overlooked in clinical laboratories and are referred to as ‘stealth-type’. Since previous reports in Japan were confined only to some geographical regions, their distribution across prefectures and the factors affecting the distribution remain unclear. Here, we revealed the dynamics of the geographical distribution of Enterobacterales with IMP-6 phenotype associated with antimicrobial use in Japan. We utilized comprehensive national surveillance data of all routine bacteriological test results from more than 1,400 hospitals in 2015 and 2016 to enumerate Escherichia coli and Klebsiella pneumoniae isolates with the antimicrobial susceptibility pattern (phenotype) characteristic of IMP-6 (imipenem susceptible, meropenem resistant), and to tabulate the frequency of isolates with the phenotype for each prefecture. Isolates were detected in approximately half of all prefectures, and combined analysis with the national data of antimicrobial usage revealed a statistically significant association between the frequency and usage of not carbapenems but third-generation cephalosporins (p = 0.006, logistic mixed-effect regression) and a weaker association between the frequency and usage of fluoroquinolones (p = 0.043). The usage of third-generation cephalosporins and fluoroquinolones may select the strains with the IMP-6 phenotype, and contribute to their occasional spread. We expect the findings will promote antimicrobial stewardship to reduce the spread of the notable carbapenemase gene.

Characterization of the Plasmidome Encoding Carbapenemase and Mechanisms for Dissemination of Carbapenem-Resistant Enterobacteriaceae

Global dissemination of carbapenem-resistant Enterobacteriaceae (CRE) threatens human health by limiting the efficacy of antibiotics even against common bacterial infections. Carbapenem resistance, mainly due to carbapenemase, is generally encoded on plasmids and is spread across bacterial species by conjugation. Most CRE epidemiological studies have analyzed whole genomes or only contigs of CRE isolates. Here, plasmidome analysis on 230 CRE isolates carrying bla_IMP was performed to shed light into the dissemination of a single carbapenemase gene in Osaka, Japan. The predominant dissemination of bla_IMP-6 by the pKPI-6 plasmid among genetically distinct isolates was revealed, as well as the emergences of pKPI-6 derivatives that acquired advantages for further disseminations. Underlying vast clonal dissemination of a carbapenemase-encoding plasmid, heteroresistance was found in CRE offspring, which was generated by the transcriptional regulation of bla_IMP-6, stabilization of bla_IMP-6 through chromosomal integration, or broadened antimicrobial resistance due to a single point mutation in bla_IMP-6.

Carbapenem-resistant Enterobacteriaceae (CRE) infections, high in morbidity and mortality, pose serious clinical challenges due to limited treatment options. A previous CRE surveillance study on 1,507 patients from 43 hospitals in Osaka, Japan, revealed that 12% of patients carried CRE and that 95% of the CRE isolates were IMP-type carbapenemase producers. Here, the mechanisms for this regional dissemination of a single carbapenemase gene were investigated. Since the dissemination of CRE is primarily due to the transmission of carbapenemase genes located on plasmids, we analyzed the plasmidome of 230 CRE isolates carrying bla_IMP by whole-genome sequencing and Southern blotting. bla_IMP-6 was found to be predominantly disseminated among chromosomally distinct isolates through the pKPI-6 plasmid. Underlying the vast clonal dissemination of pKPI-6, various subpopulations deriving from pKPI-6 were identified, which had acquired advantages for the dissemination of CRE isolates. A cluster exhibiting heteroresistance against meropenem by the transcriptional regulation of bla_IMP-6 caused an outbreak likely through covert transmission of bla_IMP-6. For stable carriage of bla_IMP-6, they occasionally integrated bla_IMP-6 on their chromosomes. In addition, we detected one isolate that broadened the range of antimicrobial resistance through a single point mutation in bla_IMP-6 on pKPI-6. Multifaceted analysis of the plasmidome granted us more accurate perspectives on the horizontal spread of CRE isolates, which is difficult to trace only by comparing the whole genomes. This study revealed the predominant spread of a specific carbapenemase-encoding plasmid accompanying the emergence of phenotypically diverse derivatives, which may facilitate further dissemination of CRE in various environments.

IMPORTANCE Global dissemination of carbapenem-resistant Enterobacteriaceae (CRE) threatens human health by limiting the efficacy of antibiotics even against common bacterial infections. Carbapenem resistance, mainly due to carbapenemase, is generally encoded on plasmids and is spread across bacterial species by conjugation. Most CRE epidemiological studies have analyzed whole genomes or only contigs of CRE isolates. Here, plasmidome analysis on 230 CRE isolates carrying bla_IMP was performed to shed light into the dissemination of a single carbapenemase gene in Osaka, Japan. The predominant dissemination of bla_IMP-6 by the pKPI-6 plasmid among genetically distinct isolates was revealed, as well as the emergences of pKPI-6 derivatives that acquired advantages for further disseminations. Underlying vast clonal dissemination of a carbapenemase-encoding plasmid, heteroresistance was found in CRE offspring, which was generated by the transcriptional regulation of bla_IMP-6, stabilization of bla_IMP-6 through chromosomal integration, or broadened antimicrobial resistance due to a single point mutation in bla_IMP-6.

Molecular and Epidemiological Characteristics of Carbapenemase-Producing Klebsiella pneumoniae Clinical Isolates in Japan

Carbapenems serve as a last resort for the clinical treatment of multidrug-resistant infections. Therefore, the rapid spread of carbapenemase-producing strains represents a serious public health threat, further limiting antibiotic choices. The current findings of hypervirulent carbapenemase-producing Klebsiella pneumoniae clinical isolates in Japan demonstrate the potential broad spread and transfer of these genes, necessitating close surveillance.

Carbapenemase-producing Enterobacteriaceae represent a serious public health threat worldwide. Carbapenemase genes, harbored on a transferable plasmid, have been isolated globally with distinct geographical features. Klebsiella pneumoniae, included in Enterobacteriaceae, also produces carbapenemase and often shows hypervirulence. Overlapping carbapenem resistance and hypervirulence in K. pneumoniae have been reported, but such strains have not yet been found in Japan. Here, we screened 104 carbapenemase-producing K. pneumoniae isolates collected from 37 hospitals and outpatient clinics in Japan between September 2014 and July 2015. PCR and DNA sequencing demonstrated IMP-1 in 21 isolates and IMP-6 in 83 isolates, 77 of which coharbored CTX-M-2. Most of the isolates showed low MICs toward imipenem and meropenem but high MICs toward penicillin and cephalosporins. Conjugation experiments with an Escherichia coli J53 recipient showed that most of the plasmids in IMP-6 producers were transferable, whereas only one-half of the plasmids in IMP-1 producers were transferable. PCR-based replicon typing and multiplex PCR identified five isolates belonging to the CG258 non-tonB79 cluster and no isolate belonging to the CG258-tonB79 cluster or sequence type 307 (ST307). Four K1-ST23 isolates, 10 K2-ST65 isolates, and 7 K2-ST86 isolates were detected that harbored virulence genes. The resistance genes in 85 isolates were transferable, but the virulence genes were not transferred. These results demonstrate the acquisition of IMP-type carbapenemase genes and CTX-M-type genes among hypervirulence isolates in Japan, warranting further attention and countermeasures. In this study, we have determined the molecular characteristics and epidemiology of IMP-6 producers that coharbored various CTX-M genes in Japan.

IMPORTANCE Carbapenems serve as a last resort for the clinical treatment of multidrug-resistant infections. Therefore, the rapid spread of carbapenemase-producing strains represents a serious public health threat, further limiting antibiotic choices. The current findings of hypervirulent carbapenemase-producing Klebsiella pneumoniae clinical isolates in Japan demonstrate the potential broad spread and transfer of these genes, necessitating close surveillance.

Evaluation of presumptive identification of Enterobacterales using CHROMagar Orientation medium and rapid biochemical tests

Background

The use of matrix‐assisted laser desorption/ionization time‐of‐flight mass spectrometry is gradually spreading among large‐scale laboratories; however, this method is impractical for small‐scale laboratories. In laboratories without access to these rapid identification methods, problems related to them remain unsolved. In this study, we aimed to develop a rapid and inexpensive method to presumptively identify Enterobacterales using CHROMagar Orientation medium.

Methods

The algorithm for presumptive identification of Enterobacteriaceae using CHROMagar Orientation medium was based on our previous studies. Modified property tests for indole, lysine decarboxylase, ornithine decarboxylase, and hydrogen sulfide were performed to evaluate the differentiation of the bacterial species.

Results

Using the type strains and clinical isolates, it was possible to conduct the property tests at a low cost, within 4 hours. The spot indole test was performed without any nonspecific reactions for the bacteria forming colored colonies. The presumptive identification of bacteria was thereby possible within 24 hours after specimen submission.

Conclusion

All these results suggest that the rapid presumptive identification of Enterobacterales is possible with this new identification method using CHROMagar Orientation medium. This is therefore a prompt and economical method that can be used in routine laboratory work.

Species Transferability of Klebsiella pneumoniae Carbapenemase-2 Isolated from a High-Risk Clone of Escherichia coli ST410

Sequence type 410 (ST410) of Escherichia coli is an extraintestinal pathogen associated with multi drug resistance. In this study, we aimed to investigate the horizontal propagation pathway of a highrisk clone of E. coli ST410 that produces Klebsiella pneumoniae carbapenemase (KPC). blaKPCencoding E. coli and K. pneumoniae isolates were evaluated, and complete sequencing and comparative analysis of blaKPC-encoding plasmids from E. coli and K. pneumoniae, antimicrobial susceptibility tests, polymerase chain reaction, multilocus sequence typing, and conjugal transfer of plasmids were performed. Whole-genome sequencing was performed for plasmids mediating KPC-2 production in E. coli and K. pneumoniae clinical isolates. Strains E. coli CPEc171209 and K. pneumoniae CPKp171210 were identified as ST410 and ST307, respectively. CPEc171209 harbored five plasmids belonging to serotype O8:H21, which is in the antimicrobial-resistant clade C4/H24. The CPKp171210 isolate harbored three plasmids. Both strains harbored various additional antimicrobial resistance genes. The IncX3 plasmid pECBHS_9_5 harbored blaKPC-2 within a truncated Tn4401a transposon, which also contains blaSHV-182 with duplicated conjugative elements. This plasmid displayed 100% identity with the IncX3 plasmid pKPBHS_10_3 from the K. pneumoniae CPKp171210 ST307 strain. The genes responsible for the conjugal transfer of the IncX3 plasmid included tra/trb clusters and pil genes coding the type IV pilus. ST410 can be transmitted between patients, posing an elevated risk in clinical settings. The emergence of a KPC-producing E. coli strain (ST410) is concerning because the blaKPC-2-bearing plasmids may carry treatment resistance across species barriers. Transgenic translocation occurs among carbapenem-resistant bacteria, which may spread rapidly via horizontal migration.

Genomic characterisation of a novel plasmid carrying blaIMP-6 of carbapenem-resistant Klebsiella pneumoniae isolated in Osaka, Japan

OBJECTIVES

To analyse plasmids carrying bla_IMP-6 in Klebsiella pneumoniae isolates obtained from multicentre carbapenem-resistant Enterobacteriaceae surveillance.

METHODS

Plasmids harbouring bla_IMP-6 were characterised by the whole-genome sequencing of four Klebsiella pneumoniae isolates carrying bla_IMP-6, and compared with the pKPI-6 plasmid, which is widespread in western Japan, through pulsed-field gel electrophoresis, Southern blotting, bacterial conjugation, and qPCR.

RESULTS

Whole-genome sequencing analysis revealed that three of the four isolates carried approximately 50 kbp plasmids similar to the pKPI-6 plasmid; however, one isolate carried a 250 kbp plasmid harbouring bla_IMP-6 (pE196_IMP6). So far, all of the reported plasmids carrying bla_IMP-6 were similar to the pKPI-6 plasmid, and this plasmid was a novel bla_IMP6-carrier. The size and transferability of this plasmid was confirmed by Southern hybridisation and conjugation experiments. It was demonstrated that the generation of plasmid pE196_IMP6 was due to an intramolecular transposition mediated by IS26, and a homologous recombination between plasmids pKPI-6 and pE013 that was obtained from another carbapenem-resistant Enterobacteriaceae isolate in this analysis. As a result of co-integration with pE013, pE196_IMP6 acquired six additional pairs of type II toxin-antitoxin systems that pKPI-6 does not carry. Transcription of all of the toxin-antitoxin systems were confirmed in an isolate carrying pE196_IMP6 by qPCR.

CONCLUSIONS

This study detected a novel plasmid carrying bla_IMP-6, and revealed the origin of this plasmid. Toxin-antitoxin system acquisition could enable pE196_IMP6 maintenance persistently through successions, even without selection pressure by the clinical usage of antimicrobials, generating broad dissemination and longer carbapenem-resistant Enterobacteriaceae colonisation duration in patients.

Antimicrobial susceptibility and distribution of extended-spectrum β-lactamases, AmpC β-lactamases and carbapenemases among Proteus, Providencia and Morganella isolated from global hospitalised patients with intra-abdominal and urinary tract infections: Results of the Study for Monitoring Antimicrobial Resistance Trends (SMART), 2008-2011

OBJECTIVES

The increasing trend of β-lactam resistance among Enterobacteriaceae is a worldwide problem. This study investigated isolates of the tribe Proteeae (Proteus, Providencia and Morganella) causing intra-abdominal and urinary tract infections from the worldwide Study for Monitoring Antimicrobial Resistance Trends (SMART) collected from 2008-2011.

METHODS

Antimicrobial susceptibility testing was performed on isolates with an ertapenem minimum inhibitory concentration >0.5mg/L or those phenotypically producing extended-spectrum β-lactamases (ESBLs). ESBLs, AmpC β-lactamases and carbapenemases were detected by multiplex PCR.

RESULTS

A total of 142 isolates, including Proteus mirabilis (n=121), Proteus vulgaris (n=3), Providencia stuartii (n=5), Providencia rettgeri (n=6) and Morganella morganii (n=7), were analysed. Proteus mirabilis was generally susceptible to ertapenem (∼90%) compared with imipenem (≤25%). The most common ESBLs were CTX-M types (n=64), followed by TEM (n=27) and SHV (n=7). CTX-M-1, CTX-M-2 and CTX-M-15 were the dominant CTX-M-type ESBLs in P. mirabilis isolates. CMY (n=14), which included CMY-2 (n=6), was the most common AmpC β-lactamase, followed by DHA (n=6) and FOX (n=4). NDM (n=7), which included NDM-1 (n=4), was the most common carbapenemase, followed by KPC (n=2). Isolates from hospital-associated infections had more complicated β-lactamase combinations than isolates from community-acquired infections.

CONCLUSION

The global emergence and spread of β-lactamase-producing Proteeae isolates are major issues in tackling antimicrobial resistance. Continuous monitoring of antimicrobial resistance trends and developing further resistance surveillance are necessary.

Trends and molecular characteristics of carbapenemase-producing Enterobacteriaceae in Japanese hospital from 2006 to 2015

BACKGROUND

The increasing number of carbapenemase-producing Enterobacteriaceae (CPE) has become a global problem. Most carbapenemases detected in Japan are imipenemase, which is an imipenem-degrading enzyme with low ability; thus, CPE could have been overlooked. Therefore, this study aimed to detect and analyze CPE, without overlooking CPE showing the low minimum inhibitory concentration phenotype.

METHODS

CPE screening was conducted on 531 ceftazidime-resistant Enterobacteriaceae isolated from Kitasato University Hospital during 2006-2015. We confirmed the presence of the carbapenemase genes (bla_IMP, bla_VIM, bla_KPC, bla_NDM, and bla_OXA-48) by multiplex polymerase chain reaction. The detected CPE strains were analyzed by antimicrobial susceptibility testing, multilocus sequence typing, conjugal experiments, replicon typing, and plasmid profiling by restriction enzyme treatment.

RESULTS

The CPE detection rate in Kitasato University Hospital within the past 10 years was 0.0003% (nine CPE strains). These nine CPE strains were identified to harbor 8 bla_IMP-1 or 1 bla_NDM-5. The CPE strains consisted of five species including Klebsiella pneumoniae and Citrobacter freundii. Six of eight bla_IMP-1 were coded by IncHI2 plasmid, and the other two were coded by IncA/C plasmid. Plasmid profiling revealed that K. pneumoniae and C. freundii isolated from the same patient harbored the same plasmid.

CONCLUSION

The CPE detection rate in this study was significantly lower than those previously reported in Japan. In one case, IncA/C plasmid transmission through different bacterial species within the body was speculated. Although the number of CPE detected was low, these results indicated that the resistance plasmid could spread to other bacterial species.

Comparison between IMP carbapenemase-producing Enterobacteriaceae and non-carbapenemase-producing Enterobacteriaceae: a multicentre prospective study of the clinical and molecular epidemiology of carbapenem-resistant Enterobacteriaceae

BACKGROUND

Carbapenem-resistant Enterobacteriaceae (CRE) are classified as carbapenemase-producing Enterobacteriaceae (CPE) and non-CPE; the majority of CPE in Japan produce IMP carbapenemase.

OBJECTIVES

We evaluated the clinico-epidemiological and microbiological information and effects of IMP-type carbapenemase production in CRE.

METHODS

Patients with isolations of CRE (MICs of meropenem ≥2 mg/L, imipenem ≥2 mg/L or cefmetazole ≥64 mg/L) from August 2016 to March 2018 were included. Microbiological analyses and WGS were conducted and clinical parameters were compared between groups. Independent predictors for the isolation of CPE from patients were identified by logistic regression. For comparing clinical outcomes, a stabilized inverse probability weighting method was used to conduct propensity score-adjusted analysis.

RESULTS

Ninety isolates (27 CPE and 63 non-CPE) were collected from 88 patients (25 CPE and 63 non-CPE). All CPE tested positive for IMP carbapenemase. Antibiotic resistance (and the presence of resistance genes) was more frequent in the CPE group than in the non-CPE group. Independent predictors for CPE isolation were residence in a nursing home or long-term care facility, longer prior length of hospital stay (LOS), use of a urinary catheter and/or nasogastric tube, dependent functional status and exposure to carbapenem. Although in-hospital and 30 day mortality rates were similar between the two groups, LOS after CRE isolation was longer in the CPE group.

CONCLUSIONS

IMP-CPE were associated with prolonged hospital stays and had different clinical and microbiological characteristics compared with non-CPE. Tailored approaches are necessary for the investigational and public health reporting, and clinical and infection prevention perspectives for IMP-CPE and non-CPE.

Genetics of Acquired Antibiotic Resistance Genes in Proteus spp

Proteus spp. are commensal Enterobacterales of the human digestive tract. At the same time, P. mirabilis is commonly involved in urinary tract infections (UTI). P. mirabilis is naturally resistant to several antibiotics including colistin and shows reduced susceptibility to imipenem. However higher levels of resistance to imipenem commonly occur in P. mirabilis isolates consecutively to the loss of porins, reduced expression of penicillin binding proteins (PBPs) PBP1a, PBP2, or acquisition of several antibiotic resistance genes, including carbapenemase genes. In addition, resistance to non-β-lactams is also frequently reported including molecules used for treating UTI infections (e.g., fluoroquinolones, nitrofurans). Emergence and spread of multidrug resistant P. mirabilis isolates, including those producing ESBLs, AmpC cephalosporinases and carbapenemases, are being more and more frequently reported. This review covers Proteus spp. with a focus on the different genetic mechanisms involved in the acquisition of resistance genes to multiple antibiotic classes turning P. mirabilis into a dreadful pandrug resistant bacteria and resulting in difficult to treat infections.

Molecular diversity of extended-spectrum β-lactamases and carbapenemases, and antimicrobial resistance

Along with the recent spread of multidrug-resistant bacteria, outbreaks of extended-spectrum β-lactamase (ESBL) and carbapenemase-producing bacteria present a serious challenge to clinicians. β-lactam antibiotics are the most frequently used antibacterial agents and ESBLs, and carbapenemases confer resistance not only to carbapenem antibiotics but also to penicillin and cephem antibiotics. The mechanism of β-lactam resistance involves an efflux pump, reduced permeability, altered transpeptidases, and inactivation by β-lactamases. Horizontal gene transfer is the most common mechanism associated with the spread of extended-spectrum β-lactam- and carbapenem resistance among pathogenic bacterial species. Along with the increase in antimicrobial resistance, many different types of ESBLs and carbapenemases have emerged with different enzymatic characteristics. For example, carbapenemases are represented across classes A to D of the Ambler classification system. Because bacteria harboring different types of ESBLs and carbapenemases require specific therapeutic strategies, it is essential for clinicians to understand the characteristics of infecting pathogens. In this review, we summarize the current knowledge on carbapenem resistance by ESBLs and carbapenemases, such as class A carbapenemases, class C extended-spectrum AmpC (ESAC), carbapenem-hydrolyzing class D β-lactamases (CHDLs), and class B metallo-β-lactamases, with the aim of aiding critical care clinicians in their therapeutic decision making.

Prediction of Uropathogens by Flow Cytometry and Dip-stick Test Results of Urine Through Multivariable Logistic Regression Analysis

Purpose

Multidrug-resistant Enterobacteriaceae in urinary tract infection (UTI) has spread worldwide; one cause is overuse of broad-spectrum antimicrobial agents such as fluoroquinolone antibacterials. To improve antimicrobial agent administration, this study aimed to calculate a probability prediction formula to predict the organism strain causing UTI in real time from dip-stick testing and flow cytometry.

Methodology

We examined 372 outpatient spot urine samples with observed pyuria and bacteriuria using dip-stick testing and flow cytometry. We performed multiple logistic-regression analysis on the basis of 11 measurement items and BACT scattergram analysis with age and sex as explanatory variables and each strain as the response variable and calculated a probability prediction formula.

Results

The best prediction formula for discrimination of the bacilli group and cocci or polymicrobial group was a model with 5 explanatory variables that included percentage of scattergram dots in an angular area of 0–25° (P<0.001), sex (P<0.001), nitrite (P = 0.002), and ketones (P = 0.133). For a predicted cut-off value of Y = 0.395, sensitivity was 0.867 and specificity was 0.775 (cross-validation group: sensitivity = 0.840, specificity = 0.760). The best prediction formula for P. mirabilis and other bacilli was a model with percentage of scattergram dots in an angular area of 0–20° (P<0.001) and nitrite (P = 0.090). For a predicted cut-off value of Y = 0.064, sensitivity was 0.889 and specificity was 0.788 (cross-validation group: sensitivity = 1.000, specificity = 0.766).

Conclusion

Simultaneous use of the calculated probability prediction formula with urinalysis results facilitates real-time prediction of organisms causing UTI, thus providing helpful information for empiric therapy.

Evaluation of inhibitor-combination mCIM for detecting MBL-producing Enterobacterales using three MBL inhibitors

The increase in carbapenemase-producing Enterobacterales (CPE), including metallo-β-lactamase (MBL) producers, is a severe global health concern. Thus, highly sensitive and specific methods for detecting MBL producers are needed. In this study, we tested the detectability of MBL-producing Enterobacterales against three types of MBL inhibitors (sodium mercaptoacetate, SMA; ethylenediaminetetraacetic acid, EDTA; and dipicolinic acid, DPA) used in combination with a modified carbapenem inactivation method (mCIM). These inhibitor-combination mCIMs were tested against 129 CPE (IMP, 93; NDM, 11; KPC, 13; NMC, 1; OXA-48, 11) and 75 non-CPE. For evaluation of MBL inhibitors, we used two concentrations for each of the three inhibitors: DPA (200 and 300 mg l^{- 1}), EDTA (5 and 10 mM), and SMA (1500 and 3000 mg l^{- 1}). The overall sensitivities of SMA, EDTA and DPA were 97.1-99.0 %, 81.7-99.0 % and 88.5-96.2 %, respectively. Moreover, each method showed high specificity (99.0-100 %). Although inhibitor-combination mCIMs were highly sensitive and specific for the detection of MBL producers, we found that sensitivity was dependent on the concentration of inhibitors.

Multiple β-Lactam Resistance Gene-Carrying Plasmid Harbored by Klebsiella quasipneumoniae Isolated from Urban Sewage in Japan

In our investigation of urban wastewater in Japan, carbapenem-resistant Klebsiella quasipneumoniae subsp. quasipneumoniae was isolated that carried the pTMSNI47-1 plasmid, which carries four β-lactamase genes and has transferability among Enterobacteriaceae. pTMSNI47-1 was found to encode a rarely reported carbapenemase, KHM-1. Cooperative effects of β-lactamases encoded by pTMSNI47-1 appeared to have broad-spectrum resistance to β-lactams. The detection of the KHM-1 gene in urban wastewater suggests that such a rare antimicrobial resistance (AMR) gene can be pooled in the environment, potentially emerging as an AMR determinant in a pathogen. When the number of β-lactamase resistance genes is increased in one plasmid, the transfer of this plasmid can confer broad-spectrum resistance to β-lactams, even if the individual gene confers narrow-spectrum resistance. The present study adds important information about the potential risk of sewage treatment plants as reservoirs and environmental suppliers of AMR genes, contributing to the public health from a One Health perspective.

The continuous emergence of carbapenemase-producing Enterobacteriaceae (CPE) presents a great public health challenge. Mitigation of CPE spread in the environment is crucial, particularly from a One Health perspective. Here we describe the isolation of CPE strain SNI47 from influent water of a sewage treatment plant in Japan. SNI47 was identified as Klebsiella quasipneumoniae subsp. quasipneumoniae by phylogenetic analysis and was resistant to β-lactams, including carbapenems. Of four plasmids detected from SNI47, the 185,311-bp IncA/C2 plasmid (pTMSNI47-1), which carried 10 drug resistance genes, including genes for four β-lactamases (bla_CTX-M-2, bla_DHA-1, bla_KHM-1, and bla_OXA-10), was transferred to Escherichia coli J53 via conjugation. The MICs of all tested β-lactams for the transconjugant were higher than for the recipient. We constructed recombinant plasmids, into which each β-lactamase gene was inserted, and used them to transform E. coli DH5α cells, demonstrating that KHM-1 enhanced carbapenem resistance. In addition, these β-lactamases were responsible for a wide-spectrum β-lactam resistance acquisition with mutual compensation. KHM-1, recognized as a rare type of metallo-β-lactamase, was detected in a transferable plasmid, from a sewage treatment plant, involved in horizontal gene transfer. The detection of such plasmids raises a health risk alarm for CPE dissemination.

IMPORTANCE In our investigation of urban wastewater in Japan, carbapenem-resistant Klebsiella quasipneumoniae subsp. quasipneumoniae was isolated that carried the pTMSNI47-1 plasmid, which carries four β-lactamase genes and has transferability among Enterobacteriaceae. pTMSNI47-1 was found to encode a rarely reported carbapenemase, KHM-1. Cooperative effects of β-lactamases encoded by pTMSNI47-1 appeared to have broad-spectrum resistance to β-lactams. The detection of the KHM-1 gene in urban wastewater suggests that such a rare antimicrobial resistance (AMR) gene can be pooled in the environment, potentially emerging as an AMR determinant in a pathogen. When the number of β-lactamase resistance genes is increased in one plasmid, the transfer of this plasmid can confer broad-spectrum resistance to β-lactams, even if the individual gene confers narrow-spectrum resistance. The present study adds important information about the potential risk of sewage treatment plants as reservoirs and environmental suppliers of AMR genes, contributing to the public health from a One Health perspective.

Antimicrobial Susceptibility and Molecular Epidemiology of Proteus mirabilis Isolates from Three Hospitals in Northern Taiwan

Of all the Proteus spp., Proteus mirabilis is the most common species identified in clinical specimens and is a leading agent of complicated urinary tract infection. This study was undertaken to understand the antimicrobial susceptibility, prevalence of antibiotic resistance genes, and molecular typing of P. mirabilis isolates collected from three hospitals in northern Taiwan. The results showed that the collected isolates of P. mirabilis were susceptible to most antibiotics except cefazolin and tigecycline. Many resistance genes were detected in the collected isolates, of which TEM genes were the most common. Resistance to third- or fourth-generation cephalosporins was related to the presence of at least one of the tested extended-spectrum β-lactamase (ESBL) or AmpC genes. The presence of the VEB-1 gene seemed to be a good predictor for both cefepime and ceftazidime resistance, which was further supported by quantitative polymerase chain reaction results. Of the four imipenem-resistant P. mirabilis isolates, three isolates could hydrolyze imipenem by mass spectrometry analysis. Molecular typing by pulsed-field gel electrophoresis showed that the pulsotyping of the selected P. mirabilis isolates was heterogeneous. By analyzing the relationship of antimicrobial resistance and the presence of resistance genes, revision of the Clinical and Laboratory Standards Institute cefepime and ceftazidime MIC breakpoints for Enterobacteriaceae to predict ESBL producers might possibly be needed.

Identification of specific protein amino acid substitutions of extended-spectrum β-lactamase (ESBL)-producing Escherichia coli ST131: a proteomics approach using mass spectrometry

The global pandemic of ESBL-producing Escherichia coli is associated with sequence type 131 (ST131). However, mechanisms of ST131 spread remain unclear. This study searched for proteins with amino acid substitutions specific for ST131 and used proteomics analysis to clarify ST131 characteristics. Five proteins had ST131-specific amino acid substitutions: uncharacterized protein YahO with E34A (m/z 7655); UPF0337 protein YjbJ with V59D, D60S and T63K (m/z 8351); uncharacterized protein YnfD with S106T (m/z 8448); and acid stress chaperone HdeA with Q92K and N94S (m/z 9714). Soluble cytochrome b562 (m/z 11783) showed seven amino acid substitutions, and the sequence differed between clade C of the pandemic clade and non-C. In silico analysis showed YahO protein-protein interaction with YjbJ, possibly related to biofilm formation. Although the function of soluble cytochrome b562 is electron transport of unknown function, its involvement in biofilm formation was predicted. HdeA was a gastric acid resistance-related protein. The function of YnfD was completely unclear. In conclusion, ST131-specific protein amino acid substitutions consisted mainly of a gastric acid resistance protein and proteins of unknown function (possibly involved in biofilm formation), which might be mechanisms for long-term colonization in the human intestinal tract.

PCR-Dipstick-Oriented Surveillance and Characterization of mcr-1- and Carbapenemase-Carrying Enterobacteriaceae in a Thai Hospital

Colistin is used as an alternative therapeutic for carbapenemase-producing Enterobacteriaceae (CPE) infections which are spreading at a very high rate due to the transfer of carbapenemase genes through mobile genetic elements. Due to the emergence of mcr-1, the plasmid-mediated colistin resistance gene, mcr-1-positive Enterobacteriaceae (MCRPEn) pose a high risk for the transfer of mcr-1-carrying plasmid to CPE, leading to a situation with no treatment alternatives for infections caused by Enterobacteriaceae possessing both mcr-1 and carbapenemase genes. Here, we report the application of PCR-dipstick-oriented surveillance strategy to control MCRPEn and CPE by conducting the PCR-dipstick technique for the detection of MCRPEn and CPE in a tertiary care hospital in Thailand and comparing its efficacy with conventional surveillance method. Our surveillance results showed a high MCRPEn (5.9%) and CPE (8.7%) carriage rate among the 219 rectal swab specimens examined. Three different CPE clones were determined by pulsed-field gel electrophoresis (PFGE) whereas only two MCRPEn isolates were found to be closely related as shown by single nucleotide polymorphism-based phylogenetic analysis. Whole genome sequencing (WGS) and plasmid analysis showed that MCRPEn carried mcr-1 in two plasmids types—IncX4 and IncI2 with ~99% identity to the previously reported mcr-1-carrying plasmids. The identification of both MCRPEn and CPE in the same specimen indicates the plausibility of plasmid-mediated transfer of mcr-1 genes leading to the emergence of colistin- and carbapenem-resistant Enterobacteriaceae. The rapidity (<2 h) and robust sensitivity (100%)/specificity (~99%) of PCR-dipstick show that this specimen-direct screening method could aid in implementing infection control measures at the earliest to control the dissemination of MCRPEn and CPE.

Molecular and epidemiological analysis of IMP-1 metallo-β-lactamase-producing Klebsiella pneumoniae in a tertiary care hospital in Japan

This study investigated the molecular and phenotypic characteristics of carbapenemase-producing Klebsiella pneumoniae, and identified the risk factors underlying its acquisition. We evaluated K. pneumoniae isolated in Nagasaki University Hospital between January 2009 and June 2015. The presence of carbapenemase genes and plasmid characteristics were investigated. We performed multilocus sequence typing (MLST), and generated a dendrogram based on the results of pulsed-field gel electrophoresis (PFGE) for carbapenemase-producing strains. We also performed a case-control study of patients. Of the 88 K. pneumoniae strains that showed minimum inhibitory concentration ≥1 μg/mL for imipenem and/or meropenem, and that were available from our bacterial collection, 18 had the IMP-type carbapenemase gene, all of which were IMP-1 according to sequencing analysis. Strains included seven different sequence types (STs), of which the most common was ST1471. A dendrogram showed the significant similarity of some strains with relationships in PFGE patterns, STs, and the wards in which they were isolated. Plasmid incompatibility group was similar among the IMP-1 producers. Regarding risk factors, multivariate analysis showed that liver disease and previous uses of carbapenems and anti-fungal drugs were significant factors for the acquisition of IMP-1-producing strains. Our results demonstrate that IMP-1 is a major carbapenemase produced by K. pneumoniae. The PFGE results indicated the possibility of transmission in the hospital. The identified risk factors should be considered for appropriate antibiotic therapy and infection-control measures.

Complete Genome Sequence of bla IMP-6-Positive Metakosakonia sp. MRY16-398 Isolate From the Ascites of a Diverticulitis Patient

A novel species of carbapenemase-producing Enterobacteriaceae (CPE) was isolated from a patient diagnosed with sigmoid colon diverticulitis. At first, laboratory testing suggested it was Klebsiella oxytoca or Pantoea sp.; however, a complete genome sequence of the isolate, MRY16-398, revealed that it could be novel species, most similar to [Kluyvera] intestini, of which taxonomic nomenclature is still under discussion. Orthologous conserved gene analysis among 42 related bacterial strains indicated that MRY16-398 was classified as the newly proposed genus Metakosakonia. Further, MRY16-398 was found to harbor the bla_IMP-6 gene-positive class 1 integron (In722) in plasmid pMRY16-398_2 (IncN replicon, 47.4 kb in size). This finding implies that rare and opportunistic bacteria could be potential infectious agents. In conclusion, our results highlight the need for continuous monitoring for CPE even in nonpathogenic bacteria in the nosocomial environment.

Occurrence and characterization of carbapenem-resistant Gram-negative bacilli: A collaborative study of antibiotic-resistant bacteria between Indonesia and Japan

OBJECTIVES

To explore the occurrence and characterization of carbapenemase-producing pathogens among carbapenem-resistant Gram-negative bacilli isolated from hospitalized patients with urinary tract infection in Indonesia.

METHODS

This was a study promoted by the Japanese-Indonesian collaborative research program in the Japan Initiative for Global Research Network on Infectious Diseases. Bacterial pathogens were prospectively isolated from urine specimens of hospitalized urinary tract infection patients at Dr. Soetomo Hospital (Surabaya, Indonesia). All Gram-negative bacteria resistant to third-generation cephalosporin or carbapenem were included in this study. Carbapenemase genes were investigated for phenotype and genotype.

RESULTS

In total, 1082 Gram-negative bacilli were isolated, of which 116 strains were resistant to imipenem or meropenem (carbapenem-resistant Gram-negative bacilli), and 22 strains were carbapenemase-producing Gram-negative bacilli. Carbapenemase-producing Gram-negative bacilli consisted of Acinetobacter baumannii (n = 4), Pseudomonas aeruginosa (n = 4), Klebsiella pneumoniae (n = 5), Providencia rettgeri (n = 4) and five others. The carbapenemase-producing Gram-negative bacilli included NDM-1 (n = 18, 81.8%, in Enterobacteriaceae and Acinetobacter spp.) and IMP-7 (n = 4, 18.2%, all in P. aeruginosa). Among carbapenem-resistant Gram-negative bacilli, all four P. aeruginosa were sensitive to colistin, and all six Acinetobacter spp. were sensitive to minocycline, colistin and tigecycline. Of those patients harboring carbapenemase-producing Gram-negative bacilli, 12 (54.5%) were seriously ill at the time of admission, with longer hospital stays and three deaths (13.6% mortality rate).

CONCLUSIONS

Urinary tract infection-causing carbapenem-resistant Gram-negative bacilli are widely disseminated in Indonesia. The NDM-1 phenotype seems to be dominant, and it can be treated with colistin and tigecycline in most cases. Most patients harboring carbapenemase-producing Gram-negative bacilli are seriously ill, have a bad prognosis, with a longer hospital stay and a significant mortality rate.

Complete Genome Sequence of a blaKPC-2-Positive Klebsiella pneumoniae Strain Isolated from the Effluent of an Urban Sewage Treatment Plant in Japan

Antimicrobial resistance genes (ARGs) and the bacteria that harbor them are widely distributed in the environment, especially in surface water, sewage treatment plant effluent, soil, and animal waste. In this study, we isolated a KPC-2-producing Klebsiella pneumoniae strain (GSU10-3) from a sampling site in Tokyo Bay, Japan, near a wastewater treatment plant (WWTP) and determined its complete genome sequence. Strain GSU10-3 is resistant to most β-lactam antibiotics and other antimicrobial agents (quinolones and aminoglycosides). This strain is classified as sequence type 11 (ST11), and a core genome phylogenetic analysis indicated that strain GSU10-3 is closely related to KPC-2-positive Chinese clinical isolates from 2011 to 2017 and is clearly distinct from strains isolated from the European Union (EU), United States, and other Asian countries. Strain GSU10-3 harbors four plasmids, including a blaKPC-2-positive plasmid, pGSU10-3-3 (66.2 kb), which is smaller than other blaKPC-2-positive plasmids and notably carries dual replicons (IncFII [pHN7A8] and IncN). Such downsizing and the presence of dual replicons may promote its maintenance and stable replication, contributing to its broad host range with low fitness costs. A second plasmid, pGSU10-3-1 (159.0 kb), an IncA/C2 replicon, carries a class 1 integron (containing intI1, dfrA12, aadA2, qacEΔ1, and sul1) with a high degree of similarity to a broad-host-range plasmid present in the family Enterobacteriaceae The plasmid pGSU10-3-2 (134.8 kb), an IncFII(K) replicon, carries the IS26-mediated ARGs [aac(6')Ib-cr,blaOXA-1, catB4 (truncated), and aac(3)-IId], tet(A), and a copper/arsenate resistance locus. GSU10-3 is the first nonclinical KPC-2-producing environmental Enterobacteriaceae isolate from Japan for which the whole genome has been sequenced.IMPORTANCE We isolated and determined the complete genome sequence of a KPC-2-producing K. pneumoniae strain from a sampling site in Tokyo Bay, Japan, near a wastewater treatment plant (WWTP). In Japan, the KPC type has been very rarely detected, while IMP is the most predominant type of carbapenemase in clinical carbapenemase-producing Enterobacteriaceae (CPE) isolates. Although laboratory testing thus far suggested that Japan may be virtually free of KPC-producing Enterobacteriaceae, we have detected it from effluent from a WWTP. Antimicrobial resistance (AMR) monitoring of WWTP effluent may contribute to the early detection of future AMR bacterial dissemination in clinical settings and communities; indeed, it will help illuminate the whole picture in which environmental contamination through WWTP effluent plays a part.

Molecular epidemiology and clinical features of extended-spectrum beta-lactamase- or carbapenemase-producing Escherichia coli bacteremia in Japan

Objectives

To identify risk factors and clinical outcomes in patients with bacteremia due to extended-spectrum beta-lactamase (ESBL) or carbapenemase-producing Escherichia coli, as well as to determine the prevalence and genetic background of such isolates.

Methods

Case control study was performed with patients with E. coli bacteremia between January 2008 and May 2013 (n = 115) at a tertiary university hospital in Japan. Cases had ESBL-producing E. coli (ESBL-EC) whereas controls had non-ESBL-producing E. coli (non-ESBL-EC) isolates. A retrospective chart review was performed to identify risk factors and clinical outcomes. Isolates were characterized by antimicrobial susceptibility testing, polymerase chain reaction analysis for beta-lactamase genes, and multi-locus sequence typing.

Results

Of 115 unique cases of E. coli bacteremia, 30 (26.1%) were due to ESBL-EC and three (2.6%) were due to carbapenemase-producing E. coli. All three carbapenemase-producing E. coli isolates were IMP-6 and concurrently produced ESBL (ESBL/IMP-6-EC). ESBL-EC isolates showed multidrug resistance. Of the ESBL-EC isolates, CTX-M-27 was the most prevalent (33.3%), followed by CTX-M-14 (30%). Multi-locus sequence typing revealed that 19 (63.3%) isolates were ST131. The multivariate analysis identified nursing home-associated infections and antibiotic administration in the preceding 30 days as risk factors for ESBL-EC bacteremia. The 14-day mortality non-ESBL-EC, ESBL-EC, and ESBL/IMP-6-EC was 4.7% (4/85), 20% (6/30), and 66.7% (2/3), respectively.

Conclusions

CTX-M-27, CTX-M-14, and ST131 were the most prevalent ESBL-EC isolates from bacteremic patients in a Japanese hospital. Further studies with larger sample sizes are warranted to investigate the clinical significance of ESBL-EC and ESBL/IMP-6-EC.

Escherichia coli Sequence Type 410 Is Causing New International High-Risk Clones

Extraintestinal pathogenic Escherichia coli (ExPEC) is the main cause of urinary tract infections and septicemia. Significant attention has been given to the ExPEC sequence type ST131, which has been categorized as a “high-risk” clone. High-risk clones are globally distributed clones associated with various antimicrobial resistance determinants, ease of transmission, persistence in hosts, and effective transmission between hosts. The high-risk clones have enhanced pathogenicity and cause severe and/or recurrent infections. We show that clones of the E. coli ST410 lineage persist and/or cause recurrent infections in humans, including bloodstream infections. We found evidence of ST410 being a highly resistant globally distributed lineage, capable of patient-to-patient transmission causing hospital outbreaks. Our analysis suggests that the ST410 lineage should be classified with the potential to cause new high-risk clones. Thus, with the clonal expansion over the past decades and increased antimicrobial resistance to last-resort treatment options, ST410 needs to be monitored prospectively.

Escherichia coli sequence type 410 (ST410) has been reported worldwide as an extraintestinal pathogen associated with resistance to fluoroquinolones, third-generation cephalosporins, and carbapenems. In the present study, we investigated national epidemiology of ST410 E. coli isolates from Danish patients. Furthermore, E. coli ST410 was investigated in a global context to provide further insight into the acquisition of the carbapenemase genes bla_OXA-181 and bla_NDM-5 of this successful lineage. From 127 whole-genome-sequenced isolates, we reconstructed an evolutionary framework of E. coli ST410 which portrays the antimicrobial-resistant clades B2/H24R, B3/H24Rx, and B4/H24RxC. The B2/H24R and B3/H24Rx clades emerged around 1987, concurrently with the C1/H30R and C2/H30Rx clades in E. coli ST131. B3/H24Rx appears to have evolved by the acquisition of the extended-spectrum β-lactamase (ESBL)-encoding gene bla_CTX-M-15 and an IncFII plasmid, encoding IncFIA and IncFIB. Around 2003, the carbapenem-resistant clade B4/H24RxC emerged when ST410 acquired an IncX3 plasmid carrying a bla_OXA-181 carbapenemase gene. Around 2014, the clade B4/H24RxC acquired a second carbapenemase gene, bla_NDM-5, on a conserved IncFII plasmid. From an epidemiological investigation of 49 E. coli ST410 isolates from Danish patients, we identified five possible regional outbreaks, of which one outbreak involved nine patients with bla_OXA-181- and bla_NDM-5-carrying B4/H24RxC isolates. The accumulated multidrug resistance in E. coli ST410 over the past two decades, together with its proven potential of transmission between patients, poses a high risk in clinical settings, and thus, E. coli ST410 should be considered a lineage with emerging “high-risk” clones, which should be monitored closely in the future.

IMPORTANCE Extraintestinal pathogenic Escherichia coli (ExPEC) is the main cause of urinary tract infections and septicemia. Significant attention has been given to the ExPEC sequence type ST131, which has been categorized as a “high-risk” clone. High-risk clones are globally distributed clones associated with various antimicrobial resistance determinants, ease of transmission, persistence in hosts, and effective transmission between hosts. The high-risk clones have enhanced pathogenicity and cause severe and/or recurrent infections. We show that clones of the E. coli ST410 lineage persist and/or cause recurrent infections in humans, including bloodstream infections. We found evidence of ST410 being a highly resistant globally distributed lineage, capable of patient-to-patient transmission causing hospital outbreaks. Our analysis suggests that the ST410 lineage should be classified with the potential to cause new high-risk clones. Thus, with the clonal expansion over the past decades and increased antimicrobial resistance to last-resort treatment options, ST410 needs to be monitored prospectively.

Characteristics of Carbapenemase-Producing Enterobacteriaceae in Wastewater Revealed by Genomic Analysis

Wastewater is considered a major source of antibiotic-resistant bacteria released into the environment. Here, we characterized carbapenemase-producing Enterobacteriaceae (CPE) in wastewater by whole-genome analysis. Wastewater samples (n = 40) were collected from municipal wastewater treatment plants and hospital wastewater in Japan and Taiwan. Samples were screened for CPE using selective media, and the obtained isolates were sequenced using an Illumina MiSeq. The isolates (n = 45) included the following microorganisms: Klebsiella quasipneumoniae (n = 12), Escherichia coli (n = 10), Enterobacter cloacae complex (n = 10), Klebsiella pneumoniae (n = 8), Klebsiella variicola (n = 2), Raoultella ornithinolytica (n = 1), Citrobacter freundii (n = 1), and Citrobacter amalonaticus (n = 1). Among the 45 isolates, 38 harbored at least one carbapenemase-encoding gene. Of these, the bla_GES (bla_GES-5, bla_GES-6, and bla_GES-24) genes were found in 29 isolates. The genes were situated in novel class 1 integrons, but the integron structures were different between the Japanese (In1439 with bla_GES-24 and In1440 with bla_GES-5) and Taiwanese (In1441 with bla_GES-5 and In1442 with bla_GES-6) isolates. Other carbapenemase-encoding genes (bla_VIM-1, bla_NDM-5, bla_IMP-8, bla_IMP-19, and bla_KPC-2) were found in one to three isolates. Notably, class 1 integrons previously reported among clinical isolates obtained in the same regions as the present study, namely, In477 with bla_IMP-19 and In73 with bla_IMP-8, were found among the Japanese and Taiwanese isolates, respectively. The results indicate that CPE with various carbapenemase-encoding genes in different genetic contexts were present in biologically treated wastewater, highlighting the need to monitor for antibiotic resistance in wastewater.

Rapid identification of carbapenemase-type blaGES and ESBL-type blaGES using multiplex PCR

Guiana extended-spectrum (GES) β-lactamases are emerging in Japan. The GES family can be classified into 2 groups, one with extended-spectrum β-lactamase (ESBL)-like activity, which hydrolyzes penicillins and cephalosporins, and the other with carbapenemase-like activity with an extended spectrum toward carbapenems. This difference is mediated by variations in a specific amino acid in the GES protein: G170 N or G170S substitutions. We developed an amplification refractory mutation system (ARMS) PCR assay that enabled rapid identification of these variant genes without sequencing.

The first multi-centre point-prevalence survey in four Japanese university hospitals

BACKGROUND

The Japanese government adopted a national action plan on antimicrobial resistance, which aims to reduce drug-resistant pathogens and antimicrobial use. A point-prevalence survey (PPS) is a useful surveillance method to gain information about hospital epidemiology; however, no multi-centre PPS has previously been performed in Japan.

AIM

To investigate general information about hospital epidemiology, healthcare-associated infections (HCAIs), and antimicrobial use in multiple Japanese university hospitals.

METHODS

In July 2016, a multi-centre PPS was conducted using a standardized protocol at four university hospitals in Japan.

FINDINGS

A total of 3199 patients were included. Median age and duration of hospital stay were 64 years and 10 days, respectively. A total of 246 (7.7%; 95% confidence interval (CI): 6.8-8.7) patients had 256 active HCAIs, and 933 (29.2%; 95% CI: 27.6-30.8) patients received 1318 antimicrobials. Pneumonia and gastrointestinal system infection were the most common HCAIs (N = 42, 16.4%), and Enterobacteriaceae (N = 49, 30.8%) were the predominant causative organisms. Carbapenems (N = 52, 17.8%), anti-MRSA medications, and cephems with antipseudomonal activity were the most frequently prescribed antimicrobials for HCAIs. As surgical prophylaxis, 46 of 278 antimicrobials (16.5%) were administered orally. Proportions of HCAI and antimicrobial use in each hospital ranged from 4.8% to 9.5% and 19.3%-35.0%, respectively.

CONCLUSION

This multi-centre PPS recorded detailed HCAI data and distinct antimicrobial use in Japanese university hospitals. Further surveillance is necessary to reduce HCAIs and formulate feasible plans to achieve the national action plan on antimicrobial resistance.

Current Trends in Antimicrobial Resistance of Escherichia coli

Escherichia coli is the most common Gram-negative bacterial pathogen, presenting both a clinical and an epidemiological challenge. In the last decade, several successful multidrug-resistant high-risk strains, such as strain E. coli ST131 have evolved, mainly due to the growing selective pressure of antimicrobial use. These strains present enhanced fitness and pathogenicity, effective transmission and colonization abilities, global distribution due to efficient dissemination, and resistance to various antimicrobial resistances. Here, we describe the emerging trends and epidemiology of resistant E. coli, including carbapenemase-producing E. coli, E. coli ST131 and colistin resistant E. coli.