Phenotypic and Genomic Characterization of ST133 Siderophore-Encoding Extensively Drug-Resistant Enterobacter hormaechei.

We identified an ST133 extensively drug-resistant Enterobacter hormaechei, C210017, with increased virulence in the Galleria mellonella infection model. Genomic analysis suggested it carried antibiotic resistance genes blaKPC-2 and mcr-9.1, and genes iutAiucABCD and iroBCDEN encoding the virulence factor, siderophores. Comparative genomics of C210017 and the 178 ST133 E. hormaechei strains in the database suggested they all belonged to serotype O3 and most strains (77.5%) carried the IncHI2 superplasmids associated with the resistance, virulence, and adaptation of the host strain.

Co-transfer of last-line antibiotic resistance and virulence operons by an IncFIBk-FII-X3-ColKP3 hybrid plasmid in Klebsiella pneumoniae.

OBJECTIVES: To characterize a clinical Klebsiella pneumoniae isolate from China co-harbouring tet(X4), blaOXA-181 and the aerobactin operon on an IncFIBk-FII-X3-ColKP3 hybrid plasmid. METHODS: A tigecycline-resistant strain was recovered from the intestinal sample of a patient. It was subjected to antimicrobial susceptibility testing, conjugation assay, virulence testing, WGS, bioinformatics analysis, plasmid stability testing and fitness cost testing. RESULTS: The strain K. pneumoniae T877 was resistant to tigecycline, intermediate to piperacillin/tazobactam and ertapenem, and positive for tet(X), blaOXA-181 and the virulence-associated operon iutAiucABCD, which were located on the same plasmid, named pKPT877-hybrid. It was 99.96% identical to the IncFIBk-FII plasmid pSCH6109-Vir (accession number CP050860) from K. pneumoniae strain SCH6109 at 96% coverage with the absence of a 50 kb region on pKPT877-hybrid; this region was highly homologous to the 51 kb IncX3-ColKP3-type, blaOXA-181-carrying plasmid pOXA181-191773 (accession number CP080367). Plasmid pKPT877-hybrid was conjugatively transferable to the ST11 K. pneumoniae strains FJ8 and KP04. pKPT877-hybrid did not have a significant impact on the fitness cost and could be maintained stably in T877. CONCLUSIONS: We report for the first time (to the best of our knowledge) the co-transfer of last-line antibiotic resistance determinants [tet(X4) and blaOXA-181] and the aerobactin operon (iutAiucABCD) by a mobile IncFIBk-FII-X3-ColKP3 hybrid plasmid, which can be stably maintained in K. pneumoniae strains, even in the absence of antibiotic selective pressure. Once the plasmid transfers to a K. pneumoniae with porin deficiency, the strain might have high levels of resistance to carbapenems and tigecycline, which are the last line of defence against infections. Heightened and continuous efforts are needed to control its dissemination.

How cognitive conflict affects judgments of learning: Evaluating the contributions of processing fluency and metamemory beliefs.

Previous research has documented that cognitive conflict affects basic cognitive processes such as memory, reasoning, and attention allocation. However, little research has explored whether its effect can be extended to higher cognitive processes such as metacognitive monitoring. The current study took a novel variant of a Stroop task that employed words presented in a color opposite to the color of the object itself (e.g., heart, presented in green) or same as the color of the object (e.g., forest, presented in green) as targets, an important form of metacognitive monitoring-judgments of learning (JOLs) was used as the measurement index to investigate the influence of cognitive conflict on metacognitive monitoring and to delineate the potential mechanisms underlying the cognitive conflict effect on JOLs. In Experiment 1, results showed that participants gave higher JOLs to consistent than to conflict words, even though cognitive conflict had little influence on memory recall. Experiment 2, employing a self-paced study task, found that conflict words were processed less rapidly than consistent ones, and the difference in processing fluency significantly mediated the cognitive conflict effect on JOLs. Experiment 3 employed an observer-learner task; the mediation analysis showed a complete mediation role of metamemory beliefs (observation JOLs) in the relationship between word type and JOLs. In Experiment 4, research results suggested that participants' beliefs about processing fluency played an important role in the cognitive conflict effect. To conclude, cognitive conflict is a reliable factor affecting higher cognitive processes (metamemory monitoring). Both processing fluency and metamemory beliefs tend to contribute to the cognitive conflict effect.

Chromosomal and Plasmid-Borne Tigecycline Resistance Genes tet(X3) and tet(X4) in Dairy Cows on a Chinese Farm.

We isolated 47 Acinetobacter strains carrying tet(X3) and 4 ST767 E. coli strains carrying tet(X4) from 296 rectal swab samples from dairy cows on a Chinese farm. tet(X3) was located on chromosomes or diverse plasmids, and tet(X4) was located on IncFIBκ/FIA(HI1)/X1 nontransferable plasmid. The coexistence of tet(X3) and carbapenemase genes, including blaOXA-58 and blaNDM-1, was detected in 9 Acinetobacter spp. These findings suggested that the use of tetracycline and other antibiotics in food production warrants urgent attention.

Occurrence of Plasmid- and Chromosome-Carried mcr-1 in Waterborne Enterobacteriaceae in China.

The aim of this study was to investigate the prevalence of the polymyxin resistance gene mcr-1 in Enterobacteriaceae from environmental water sources in Hangzhou, China. Colistin-resistant bacteria were isolated from environmental water samples using an enrichment broth culture method, were screened for mcr-1, and then were analyzed for the location and transferability of mcr-1 Isolates positive for mcr-1 were further examined to determine their susceptibility profiles and were screened for the presence of additional resistance genes. Twenty-three mcr-1-positive isolates (16 Escherichia coli, two Citrobacter freundii, two Klebsiella oxytoca, two Citrobacter braakii, and one Enterobacter cloacae) were isolated from 7/9 sampling locations; of those, eight mcr-1-positive isolates also contained ß-lactamase-resistance genes, eight contained qnrS, and 10 contained oqx No mcr-2-positive isolates were identified. The majority of isolates demonstrated a low to moderate level of colistin resistance. Transconjugation was successfully conducted from 14 of the 23 mcr-1-positive isolates, and mcr-1 was identified on plasmids ranging from 60 to 220 kb in these isolates. Conjugation and hybridization experiments revealed that mcr-1 was chromosome-borne in only three isolates. Pulsed-field gel electrophoresis showed that the majority of E. coli isolates belonged to different clonal lineages. Multilocus sequence typing analysis revealed that sequence type 10 (ST10) was the most prevalent, followed by ST181 and ST206. This study demonstrates the utility of enrichment broth culture for identifying environmental mcr-1-positive isolates. Furthermore, it highlights the importance of responsible agriculture and clinical use of polymyxins to prevent further widespread dissemination of polymyxin-resistant pathogens.

Emergence of Carbapenem-Resistant Serotype K1 Hypervirulent Klebsiella pneumoniae Strains in China.

We report the emergence of five carbapenem-resistant K1 hypervirulent Klebsiella pneumoniae (hvKP) strains which caused fatal infections in hospital patients in Zhejiang Province, China, upon entry through surgical wounds. Genotyping results revealed the existence of three genetically related strains which exhibited a new sequence type, ST1797, and revealed that all strains harbored the magA and wcaG virulence genes and a plasmid-borne bla(KPC-2) gene. These findings indicate that K1 hvKP is simultaneously hypervirulent, multidrug resistant, and transmissible.

Dissemination of the same cfr-carrying plasmid among methicillin-resistant Staphylococcus aureus and coagulase-negative staphylococcal isolates in China.

Six cfr-harboring methicillin-resistant Staphylococcus aureus (MRSA) isolates, which belonged to the same clone of sequence type 5 (ST5)-staphylococcal cassette chromosome mec element II (SCCmec II)-spa t311, were investigated in this study. Complete sequencing of a cfr-carrying plasmid, pLRSA417, revealed an 8,487-bp fragment containing a Tn4001-like transposon, cfr, orf1, and ISEnfa4. This segment, first identified in an animal plasmid, pSS-01, was observed in several plasmids from clinical coagulase-negative staphylococci in China, suggesting that the cfr gene, which might originate from livestock, was located in the same mobile element and disseminated among different clinical staphylococcal species.

Emergence of Escherichia coli sequence type 131 isolates producing KPC-2 carbapenemase in China.

Twenty-two KPC-2-producing Escherichia coli isolates were obtained from three hospitals in Hangzhou, China, from 2007 to 2011. One isolate, with OmpC porin deficiency, exhibited high-level carbapenem resistance. Pulsed-field gel electrophoresis showed that few isolates were indistinguishable or closely related. Multilocus sequence typing indicated that sequence type 131 (ST131) was the predominant type (9 isolates, 40.9%), followed by ST648 (5 isolates), ST405 (2 isolates), ST38 (2 isolates), and 4 single STs, ST69, ST2003, ST2179, and ST744. Phylogenetic analysis indicated that 9 group B2 isolates belonged to ST131, and 5 of 11 group D isolates belonged to ST648. Only one group B1 isolate and one group A isolate were identified. A representative plasmid (pE1) was partially sequenced, and a 7,788-bp DNA fragment encoding Tn3 transposase, Tn3 resolvase, ISKpn8 transposase, KPC-2, and ISKpn6-like transposase was obtained. The blaKPC-2-surrounding sequence was amplified by a series of primers. The PCR results showed that 13 isolates were consistent with the genetic environment in pE1. It is the first report of rapid emergence of KPC-2-producing E. coli ST131 in China. The blaKPC-2 gene of most isolates was located on a similar genetic structure.

Emergence of plasmid-mediated tigecycline resistance tet(X4) gene in Enterobacterales isolated from wild animals in captivity.

Background: Over the past few decades, antimicrobial resistance (AMR) has emerged as a global health challenge in human and veterinary medicine. Research on AMR genes in captive wild animals has increased. However, the presence and molecular characteristics of tet(X)-carrying bacteria in these animals remain unknown. Methods: Eighty-four samples were collected from captive wild animals. tet(X) variants were detected using polymerase chain reaction and the isolates were identified using matrix-assisted laser desorption/ionization time-of-flight mass spectrometry. All isolated strains were subjected to antimicrobial susceptibility testing and whole-genome sequencing. The virulence of an Escherichia coli strain carrying enterotoxin genes was assessed using a Galleria mellonella larval model. Results: We isolated two tet(X4)-positive E. coli strains and one tet(X4)-positive Raoultella ornithinolytica strain. Antimicrobial susceptibility tests revealed that all three tet(X4)-carrying bacteria were sensitive to the 13 tested antimicrobial agents, but exhibited resistance to tigecycline. Notably, one tet(X4)-carrying E. coli strain producing an enterotoxin had a toxic effect on G. mellonella larvae. Whole-genome sequencing analysis showed that the two tet(X4)-carrying E. coli strains had more than 95% similarity to tet(X4)-containing E. coli strains isolated from pigs and humans in China. Conclusion: The genetic environment of tet(X4) closely resembled that of the plasmid described in previous studies. Our study identified tet(X4)-positive strains in wildlife and provided valuable epidemiological data for monitoring drug resistance. The identification of enterotoxin-producing E. coli strains also highlights the potential risks posed by virulence genes.

Effective Motion Self-Learning Genre Using 360° Virtual Reality Content on Mobile Device: A Study Based on Taichi Training Platform.

Online fitness training, with its affordability and flexibility, offers a convenient way for individuals to engage in regular workouts that promote physical and mental health. Yet, learning fitness motions in this way presents various challenges and may not always be as effective as in-person training. To address the practical demands of motion learning, we conducted a systematic survey and accordingly proposed a four-stage self-learning genre that integrates immersive virtual reality (VR) environments with motion skill learning theories, strategies, and expert experience. Herein, we merged progressive structures and multi-level visual cues to enhance instruction, and proposed a fine-grained motion analysis method to provide adaptive correction feedback during training. Utilizing a Taichi training platform with the genre embedded, we systematically validated the effectiveness of the genre, and examined the potential impact of VR content presentation form on motion learning among different age groups, as well as their preferences and focus on VR fitness training genre design. Results from the quantitative analysis, qualitative evaluation, and case study showed that the 360° video-based VR content brought more positive motion learning performance and user experiences than the fully-simulated VR used in many previous studies. The proposed genre demonstrated outstandingly performance, experience, and usability, with each stage and design playing an effective role. Moreover, we offer several design considerations for VR fitness systems targeting diverse age groups, providing beneficial insights for VR development in the sports and health-related fields.

Phenotypic and genomic characteristics of clinical IMP-producing Klebsiella spp. Isolates in China.

BACKGROUND: IMP-producing Klebsiella spp. (IMPKsp) strains have spread globally, including in China. Currently, the prevalence and genomic characterization of IMPKsp is largely unknown nationwide. Here we aimed to provide a general overview of the phenotypic and genomic characteristics of IMPKsp strains. METHODS: 61 IMPKsp strains were obtained from 13 provinces in China during 2016-2021. All strains were tested for their susceptibility to antimicrobial agents by the microdilution broth method and sequenced with Illumina next-generation sequencing. We performed conjugation experiments on thirteen representative strains which were also sequenced by Oxford nanopore sequencing technology to characterize blaIMP-encoding plasmids. RESULTS: We find that all IMPKsp strains display multidrug-resistant (MDR) phenotypes. All strains belong to 27 different STs. ST307 emerges as a principal IMP-producing sublineage. blaIMP-4 is found to be the major isoform, followed by blaIMP-38. Seven incompatibility types of blaIMP-encoding plasmids are identified, including IncHI5 (32/61, 52.5%), IncN-IncR (10/61, 16.4%), IncFIB(K)-HI1B (7/61, 11.5%), IncN (5/61, 8.2%), IncN-IncFII (2/61, 3.3%), IncFII (1/61, 1.6%) and IncP (1/61, 1.6%). The strains carrying IncHI5 and IncN plasmids belong to diverse ST types, indicating that these two plasmids may play an important role in the transmission of blaIMP genes among Klebsiella spp. strains. CONCLUSIONS: Our results highlight that multi-clonal transmission, multiple genetic environments and plasmid types play a major role in the dissemination process of blaIMP genes among Klebsiella spp. IncHI5 type plasmids have the potential to be the main vectors mediating the spread of the blaIMP genes in Klebsiella spp.

Antibiotic resistance occurs when bacteria evolve to withstand antibiotic drugs. We are aware that a bacteria called Klebsiella is rapidly becoming resistant to carbapenems, a class of broad-spectrum antibiotics. In this study, we conducted a genetic and microbiological surveillance study across 13 provinces of China to understand factors that contribute to the growing bacterial drug resistance. We find that the way the multiple bacterial types interact with each other and swap certain genetic material may be the main cause of growing resistance. These findings call for close monitoring of genetic evolution as a matter of public health management strategy.

High intestinal carriage of Clostridium perfringens in healthy individuals and ICU patients in Hangzhou, China.

Clostridium perfringens has emerged as a growing public health concern due to its ability to cause various infections and its increasing resistance to antibiotics. To assess its current epidemiology in clinical settings, we conducted a survey involving 426 healthy individuals and 273 ICU inpatients at a provincial hospital in China. Our findings revealed a high prevalence of C. perfringens in healthy individuals (45.77%, 95% CI: 41.0%-50.6%) and ICU patients (12.82%, 95% CI: 9.1%-17.4%). The identified 220 C. perfringens isolates displayed substantial resistance to erythromycin (57.9%), clindamycin (50.7%), and tetracycline (32.0%), primarily attributed to the presence of erm(Q) (54.4%), lnu(P) (13.8%), tetB(P) (83.6%), and tetA(P) (66.7%). Notably, C. perfringens isolates from this particular hospital demonstrated a high degree of sequence type diversity and phylogenic variation, suggesting that the potential risk of infection primarily arises from the bacteria's gut colonization rather than clonal transmissions within the clinical environment. This study provides an updated analysis of the current epidemiology of C. perfringens in healthy individuals and ICU patients in China and emphasizes the need to optimize intervention strategies against its public health threat. IMPORTANCE: Clostridium perfringens is a bacterium of growing public health concern due to its ability to cause infections and its increasing resistance to antibiotics. Understanding its epidemiology in clinical settings is essential for intervention strategies. This study surveyed healthy individuals and ICU inpatients in a provincial hospital in China. It found a high prevalence of C. perfringens, indicating infection risk. The isolates also showed significant antibiotic resistance. Importantly, the study revealed diverse sequence types and phylogenetic variation, suggesting infection risk from intestinal colonization rather than clonal transmission in hospitals. This analysis emphasizes the need to optimize intervention strategies against this public health threat.

Prevalence and genomic characterization of clinical Escherichia coli strains that harbor the plasmid-borne tet(X4) gene in China.

The tigecycline resistance gene tet(X4) has been widely reported in animals and animal products in some Asian countries including China in recent years but only sporadically detected in human. In this study, we investigated the prevalence and genetic features of tet(X4)-positive clinical E. coli strains. A total of 462 fecal samples were collected from patients in four hospitals located in four provinces in China in 2023. Nine tet(X4)-positive E. coli strains were isolated and subjected to characterization of their genetic and phenotypic features by performing antimicrobial susceptibility test, whole-genome sequencing, bioinformatic and phylogenetic analysis. The majority of the test strains were found to exhibit resistance to multiple antimicrobial agents including tigecycline but remained susceptible to colistin and meropenem. A total of seven different sequence types (STs) and an unknown ST type were identified among the nine tet(X4)-positive strains. Notably, the tet(X4) gene in six out of these nine tet(X4)-positive E. coli strains was located in a IncFIA-HI1A-HI1B hybrid plasmid, which was an tet(X4)-bearing epidemic plasmid responsible for dissemination of the tet(X4) gene in China. Furthermore, the tet(X4) gene in four out of nine tet(X4)-positive E. coli isolates could be successfully transferred to E. coli EC600 through conjugation. In conclusion, this study characterized the epidemic tet(X4)-bearing plasmids and tet(X4)-associated genetic environment in clinical E. coli strains, suggested the importance of continuous surveillance of such tet(X4)-bearing plasmids to control the increasingly widespread dissemination of tigecycline-resistant pathogens in clinical settings in China.

MALDI-TOF MS combined with AUC method for tigecycline susceptibility testing in Escherichia coli.

Objectives: The wide spread of tet(X4) gene orthologues in the environment, food, poultry and humans is causing serious tigecycline resistance. Consequently, developing a fast and universal method to detect tigecycline resistance has become increasingly important. Methods: During 2019-2022, 116 Escherichia coli isolates were obtained from nine provinces in China. All isolates were tested for their susceptibility to antimicrobial agents by the microdilution broth method and for the tet(X4) gene by PCR. Ten tet(X4)-positive E. coli isolates were used to confirm certain conditions, including the optimal incubation time, the optimal concentration of tigecycline, and the cut-off of the relative growth (RG) value. Results: The optimal time and concentration of tigecycline for separation of susceptible and resistant isolates was 2 h and 4 mg/L, and the RG cut-off value was 0.4. We validated whether the experiment was feasible using 116 isolates of E. coli. The method yielded a susceptibility of 94.9% (95% CI: 81.4%-99.1%) and a specificity of 96.1% (95% CI: 88.3%-99.0%). Conclusions: This research has shown that this optical antimicrobial susceptibility testing method can rapidly differentiate between susceptible and resistant phenotypes in isolates of E. coli. In the same range as the current gold-standard methods, the clinical turnaround time is reduced from 48 h to 2.5 h. The above results suggest that the method has splendid specificity and operationality.

Molecular typing of CTX-M-producing escherichia coli isolates from environmental water, swine feces, specimens from healthy humans, and human patients.

CTX-M-producing Escherichia coli is the predominant type of extended-spectrum ß-lactamase (ESBL)-producing E. coli worldwide. In this study, molecular typing was conducted for 139 CTX-M-producing E. coli isolates, phenotypically positive for ESBLs, isolated from environmental water, swine, healthy humans, and hospitalized patients in Hangzhou, China. The antibiotic resistance profiles of the isolates for the cephalosporins and fluoroquinolones were determined. The isolates showed 100% resistance to cefotaxime and ceftriaxone while maintaining relatively high susceptibility to cefoxitin, cefepime, and ceftazidime. A total of 61.9% (86/139) of the isolates, regardless of origin, showed high resistance to fluoroquinolones. PCRs and DNA sequencing indicated that blaCTX-M-14 was the most prevalent CTX-M-9 group gene and that blaCTX-M-15 and blaCTX-M-55 were the dominant CTX-M-1 group genes. Isolates from all sources with CTX-M types belonging to the CTX-M-1 or CTX-M-9 group were most frequently associated with epidemics. Molecular homology analysis of the isolates, conducted by phylogenetic grouping, pulsed-field gel electrophoresis (PFGE), and multilocus sequence typing (MLST), demonstrated that the dominant clones belonged to B2-ST131, D-ST648, D-ST38, or A-CC10. These four sequence types (STs) were discovered in E. coli isolates both from humans and from environmental water, suggesting frequent and continuous intercompartment transmission between humans and the aquatic environment. Seven novel sequence types were identified in the current study. In conclusion, this study is the first to report the molecular homology analysis of CTX-M-producing E. coli isolates collected from water, swine, and healthy and hospitalized humans, suggesting that pathogens in the environment might originate both from humans and from animals.

Escherichia coli high-risk clone ST410 harboring blaNDM-13 isolated from hospital wastewater in China.

A carbapenem-resistant Escherichia coli strain C-SRM-3 was isolated from hospital wastewater effluent in Hangzhou city, China in March 2022. Analysis of the whole genome sequence showed that this blaNDM-13-positive strain belonged to an internationally recognized high-risk clone ST410 responsible for the dissemination of carbapenem resistance in E. coli. This isolate displayed a multidrug-resistant phenotype and carried a cassette of antibiotic-resistant genes. blaNDM-13 gene was successfully transferred to the recipient E. coli C600 via conjugation. WGS results revealed that blaNDM-13 gene was located on an IncI1 type plasmid replicon. The phylogenetic reconstruction showed that wastewater-sourced C-SRM-3 strain was located in a single branch, far removed from human-derived and animal-sourced isolates. The detection of blaNDM-13 in hospital wastewater suggests that continuous monitoring of antibiotic-resistant genes in the environment is critical for the prevention of carbapenem-resistant bacteria spreading.

Population genomic analysis reveals the emergence of high-risk carbapenem-resistant Escherichia coli among ICU patients in China.

OBJECTIVES: The increasing incidence of carbapenem-resistant Enterobacterales (CRE) mediated nosocomial infections has caused a significant public health burden globally. Currently, the prevalence and genomic characteristics of carbapenem-resistant Escherichia coli (CREC) in patients admitted to the intensive care unit (ICU) are unknown. METHODS: Herein, we present a nationwide genomic investigation of CREC isolates among ICU patients in China in 2018 and 2020. In total, 113 CREC isolates were identified from 1105 samples in 25 hospitals, and investigated with phenotyping and genomics approaches. RESULTS: Carbapenemases were produced in 94.69% (107/113) of CREC isolates, which comprise KPC-2 (n = 53, 49.53%), NDM (n = 51, 47.66%), IMP-4 (n = 2, 1.87%), and OXA-181 (n = 1, 0.93%). Notably, CREC isolates co-carrying mcr-9 and blaNDM-5 or tet(X4) and blaNDM-5 were first identified in clinical settings. The carbapenemase genes of most isolates were located on the plasmids. The blaKPC gene was mainly mediated by IncFII plasmids (n = 37, 69.81%), and blaNDM was located on the IncX3 plasmid (n = 36, 70.59%). CREC isolates belonged to diverse sequence types (STs) of which ST131 was the most prevalent blaKPC-positive CREC isolates (34/113, 30.09%), while blaNDM was associated with ST617 and ST410 isolates, thereby indicating that multiple CREC clones spread in Chinese ICU patients. CONCLUSIONS: This study highlights the emerging threat of high-risk CREC isolates such as ST131 circulating in the ICU in China. Hence, stringent monitoring of such high-risk clones should be performed.

Emergence of the clinical rdar morphotype carbapenem-resistant and hypervirulent Klebsiella pneumoniae with enhanced adaption to hospital environment.

Klebsiella pneumoniae has evolved into strains of various phenotypes that pose a grave threat to human health in the past few decades. This study investigated a novel morphotype of K. pneumoniae with enhanced adaption to the hospital environment. Clinical K. pneumoniae were characterized by different genotypic and phenotypic tests. Gene knockout and complementation experiments were used to confirm the genetic changes that led to the morphological changes. ST15 carbapenem-resistant and hypervirulent (CR-hvKP) clinical strains with the "red, dry and rough" (rdar) morphotype were increasingly detected in hospitals in China. Strains with the rdar phenotype were found to be less virulent compared with that with typical morphologies but exhibit enhanced ability to adhere to the surface of various materials, and hence a dramatically increased rate of survival on various materials commonly found in the hospital environment. Comparative genomics analysis and gene function studies suggested the rdar morphotype was due to a G579D substitution in the BcsA protein which enabled the strain to produce a large amount of cellulose. These findings show evolutional phenotypic change enables K. pneumoniae strains to better survive both in human and hospital environments, facilitating its persistence and further dissemination.

Emergence of Proteus mirabilis harboring blaKPC-2 and qnrD in a Chinese Hospital.

Nineteen carbapenem-nonsusceptible Proteus mirabilis isolates were recovered from intensive care units in the Second Affiliated Hospital of Zhejiang University during a 3-month period. The isolates showed a high level of resistance against ciprofloxacin, in addition to their resistance against the carbapenems. Pulsed-field gel electrophoresis (PFGE) analysis showed that these isolates belonged to three clonal strains. PCRs and DNA sequence analysis of the carbapenemase and other ß-lactamase genes indicated that all the isolates harbored the bla(KPC-2) gene. Twelve of 19 isolates harbored the plasmid-mediated quinolone resistance (PMQR) genes, both the qnrD and aac(6')-Ib-cr genes. Eight representative isolates with high levels of quinolone resistance carried the similar mutation profiles of S83I in gyrA, E466D in gyrB, and S80I in parC. Reduced carbapenem susceptibility was transferred to Escherichia coli (EC600) in a conjugation experiment, while the quinolone resistance was not. DNA hybridization showed that qnrD was located on a plasmid of approximately 4.5 kb. In summary, large clonally related isolates of KPC-2-producing P. mirabilis emerged in a Chinese hospital, and qnrD was detected in KPC-producing P. mirabilis for the first time.

A ten years (2000-2009) surveillance of resistant Enterobacteriaceae in Zhejiang Province, China.

OBJECTIVE: In Zhejiang Province, there are several highly developed cities near the coast and several relatively under-developed mountain areas. Analysis of the composition of bacteria isolated from patients as well as their antibiotic resistance profile from various areas of this province, and tracing of such data year-by-year, will help to delineate the bacterial resistance profile of these areas and to understand how the stage of socio-economical development impacts on the composition of clinical micro-flora and their resistance profile. METHODS: In order to investigate variation in resistance rates and isolation rates of Enterobacteriaceae, from 2000 to 2009 in Zhejiang Province, China, Enterobacteriaceae isolated from 15 hospitals located in different regions of the province were surveyed. RESULTS: The total numbers of the Enterobacteriaceae isolated increased more than 20-fold from 2000 to 2009. Among the Enterobacteriaceae, Escherichia coli and Klebsiella pneumoniae were the dominant isolates. The percentage of E. coli and K. pneumoniae that produced detectable extended-spectrum ß-lactamases (ESBLs) increased from 2000 to 2007, and then declined slightly in 2008 and 2009. The percentages of K. pneumoniae and E. coli that were resistant to ceftazidime increased sharply from 2000 to 2009. There were remarkable increases in the carbapenem resistant rates during the decade, but they were much higher for the isolates from the developed cities than from the rural areas. In 2002, carbapenem-resistant E. coli was first found in Hangzhou, one of the highly developed cities in Zhejiang Province. By 2009, carbapenem-resistant bacteria were found for all species of Enterobacteriaceae surveyed in almost all areas of the province, although they were more frequently identified in developed areas than in rural areas. CONCLUSION: Much restrictive actions have to be taken in terms of rational use of antibiotics and nosocomial control to prevent the further spread of the drug-resistant pathogens.