Multidrug Resistance Mechanisms of Carbapenem Resistant Klebsiella pneumoniae Strains Isolated in Chongqing, China

Systematic Review and Meta-Analysis on Prevalence and Antimicrobial Resistance Patterns of Important Foodborne Pathogens Isolated from Retail Chicken Meat and Associated Environments in India

The chicken value chain, a vital part of the global food supply, also represents a significant public health concern due to the risk of foodborne pathogens, particularly in low- and middle-income countries (LMICs) such as India. This systematic review and meta-analysis aimed to assess the prevalence of significant bacterial pathogens including Salmonella spp., Campylobacter spp., Escherichia coli, Staphylococcus aureus, Listeria monocytogenes, Clostridium perfringens, and Klebsiella pneumonia. in retail chicken meat and associated environments and the antimicrobial resistance based on the articles published between January 2010-December 2023. The research adhered to the guidelines in the 'Preferred Reporting Items for Systematic Review and Meta-Analysis' (PRISMA). Based on 90 included studies, S. aureus showed the highest pooled prevalence (56%; 95% CI: 38-74%), followed by E. coli (50%; 95% CI: 37-64%), C. perfringens (35%; 95% CI: 10-65%), and K. pneumoniae (21%; 95% CI: 7-38%). Salmonella spp. (95% CI: 11-26%) and Campylobacter spp. (95% CI: 11-27%) exhibited similar prevalence rates at 18%, while L. monocytogenes had the lowest prevalence at 13% (95% CI: 1-33%). A sensitivity analysis was subsequently conducted to assess the impact of influential studies, and the pooled prevalence of each pathogen was recalculated after removing these studies to ensure the robustness of the results. The pathogens, specifically Salmonella spp. and Campylobacter spp., displayed high levels of resistance to medically important antimicrobials (erythromycin, tetracycline, ciprofloxacin, colistin), a potential threat to human health. This study advocates for a collaborative and comprehensive approach, reflecting the multifaceted nature of the issue, and highlighting the importance of a holistic strategy to safeguard public health and maintain antibiotic effectiveness in the face of emerging challenges.

The Characterisation of Carbapenem-Resistant Acinetobacter baumannii and Klebsiella pneumoniae in a Teaching Hospital in Malaysia

Background/Objectives: The emergence and dissemination of carbapenem-resistant organisms, particularly Acinetobacter baumannii and Klebsiella pneumoniae, pose a significant threat to healthcare systems worldwide. This retrospective study aims to characterise carbapenem-resistant Acinetobacter baumannii (CRAB) and carbapenem-resistant Klebsiella pneumoniae (CRKP) strains in a teaching hospital and to determine the risk factors associated with patients' in-hospital mortality. Methods: A total of 90 CRAB and 63 CRKP were included in this study. Carbapenemase genes and MLST types of CRAB and CRKP were determined using specific primers. Risk factors associated with in-hospital mortality were analysed with collected data. Results: All the CRAB strains consisted of OXA carbapenemase genes, with 98% of the strains co-harbouring blaOXA-23-like and blaOXA-51-like carbapenemase genes. Conversely, blaNDM is the predominant carbapenemase gene in CRKP, followed by blaOXA-48-like carbapenemase genes. ST2 and ST20 are the dominant MLST types in CRAB and CRKP, respectively. In CRAB, multivariate analysis identified age, ethnicity, the presence of a mechanical ventilator, and patients who experienced previous exposure to clindamycin in the last 90 days as associated with an increased risk of in-hospital mortality. In contrast, older age, male, ICU admission, and the presence of an indwelling urinary catheter were significantly associated with an increased risk of mortality for patients with CRKP. Conclusions: Both CRAB and CRKP lead to high rates of mortality. The MLST profile showed that the genomic patterns of CRKP were highly diverse, whereas CRAB strains had low genetic diversity. To tackle these challenging pathogens, robust surveillance and an in-depth understanding of molecular epidemiology and genomics studies are needed to tailor infection control strategies and individualise treatment approaches.

Epidemiology of carbapenem-resistant Klebsiella pneumoniae in China and the evolving trends of predominant clone ST11: a multicentre, genome-based study

OBJECTIVES

Carbapenem-resistant Klebsiella pneumoniae (CRKP) is a major nosocomial infectious pathogen with rapidly increasing prevalence. The genomic epidemiological characteristics of CRKP nationwide, especially the evolving trends within the predominant clones, should be evaluated clearly.

METHODS

We collected 3415 K. pneumoniae strains from 28 hospitals across China. Antimicrobial susceptibility testing and WGS were performed. Subsequent genomic analyses, including sequence typing, K-locus (KL) identification, antimicrobial resistance gene screening, and virulence score assessment were performed. The phylogenetic relationship of clonal group 11 was determined based on core-genome analysis, and the presence of the pLVPK-like virulence plasmid in ST11 isolates was confirmed using plasmid core-gene analysis. Additionally, the trends of the ST11 lineage with different KL types on a global scale were investigated using Beast2.

RESULTS

Of the K. pneumoniae strains, 708 were identified as CRKP isolates (20.7%), of which 97.7% were MDR. ST11 was the predominant clone, and KPC-2 was the prevalent carbapenemase in China, although the prevalence of specific clones and carbapenemases varied by geographic region. Among ST11 isolates, KL47 and KL64 were the predominant KL types, and KL64 gradually replaced KL47, with a higher percentage of KL64 isolates harbouring the pLVPK-like plasmid. Global genome data showed a significant increase in the effective population size of KL64 over the last 5 years.

CONCLUSIONS

The prevalence of CRKP was very high in certain regions in China. The increasing convergence of virulence and resistance, particularly in ST11-KL64 isolates, should be given more attention and further investigation.

Molecular characteristics and antimicrobial resistance profiles of Carbapenem-Resistant Klebsiella pneumoniae isolates at a tertiary hospital in Nanning, China

PURPOSE

Carbapenem resistant Klebsiella pneumoniae is associated with nosocomial infections and can cause high mortality, which poses great threat to human health. This study was aimed at investigating the molecular epidemiology and antimicrobial resistance profiles of carbapenem resistant Klebsiella pneumoniae isolates and providing clues for management and control of carbapenem resistant Klebsiella pneumoniae infections.

METHODS

A total of 2324 Klebsiella pneumoniae strains were isolated from the First Affiliated Hospital of Guangxi Medical University from June 2018 to October 2020, and 103 carbapenem resistant Klebsiella pneumoniae strains from inpatients were collected, and the specimens mainly came from the sputum, urine, secretions, and blood. The antimicrobial susceptibility tests were performed using the VITEK 2 Compact system or the Kirby-Bauer disk-diffusion method. The resistance genes were detected by polymerase chain reaction and sequencing. The homology analysis of carbapenem resistant Klebsiella pneumoniae strains was performed by multilocus sequence typing.

RESULTS

Antimicrobial susceptibility results showed that the 103 carbapenem resistant Klebsiella pneumoniae strains were resistant to most common antibiotics. Resistance genes detection showed that the carbapenem resistant Klebsiella pneumoniae isolates mainly carried metallo-beta-lactamase, and the predominant gene was NDM-1. The homology analysis found that the major ST type were ST11, follow by ST15 and ST17.

CONCLUSION

The carbapenem resistant Klebsiella pneumoniae isolates in our study shown resistance to most common antibiotics. Of the 103 carbapenem resistant Klebsiella pneumoniae strains, 91 strains (88.35%) carried carbapenemases genes, and NDM was the predominant carbapenemase gene detected. ST11 was the major ST typing of carbapenem resistant Klebsiella pneumoniae in our hospital. Our finding may play a role in control and management of the carbapenem resistant Klebsiella pneumoniae infections and guiding clinical antibiotic therapy. In addition, metallo-beta-lactamase should be served as a key target to be monitored in carbapenem resistant Klebsiella pneumoniae infection.

Dissemination and characteristics of carbapenem-resistant Klebsiella pneumoniae in nine district hospitals in southwestern China

Background

Carbapenem-resistant Klebsiella pneumoniae (CRKP) is epidemically transmitted globally, but few studies focused on the prevalence in district-level hospitals. In this study, we investigated CRKP strains collected from nine district hospitals from September 2019 to September 2020, aiming to determine the resistance mechanisms, virulence profiles, and molecular epidemiological characteristics of CRKP in district hospitals in Southwest China.

Methods

A total of 51 CRKP strains were collected from 9 district-level hospitals. Matrix-assisted laser desorption/ionization-time of flight mass spectrometer was used for strain identification review, and the micro-broth dilution method was used for antibiotic sensitivity detection. Molecular epidemiological investigation of strains was performed by multilocus sequence typing (MLST) and pulsed-field gel electrophoresis (PFGE) methods. PCR and efflux pump inhibition tests were used to detect CRKP resistance mechanisms. PCR and serum killing tests were used to detect capsular serotype, virulence-related genes, and virulence validation.

Results

The CRKP strains in district hospitals presented high levels of MIC50 and MIC90 in carbapenem antibiotics especially ertapenem and meropenem. A total of 90.2% (46/51) CRKP strains were detected as carbapenemase producers, and the proportion of strains co-expressing carbapenemases was 11.8% (6/51). All CRKP strains were grouped into eight MLST types, and ST11 was the most prevalent genotype. A total of 11.8% (6/51) CRKP isolates were positive for the string test, and three strains of hypervirulent and carbapenem-resistant K. pneumoniae (HV-CRKP) were positive in serum killing test. The molecular typing of all the CRKP isolates was grouped into 29 different PFGE patterns, and 40 ST11 isolates belonged to 20 different PFGE clusters.

Conclusion

CRKP strains showed high-level antibiotic resistance and virulence phenotype in district hospitals in Southwest China, which suggested that we should immediately pay attention to the rapid dissemination of the CRKP in regional hospitals. Our study will provide new insights into the epidemiology of CRKP in regional hospitals, which will help regional hospitals develop nosocomial infection prevention and control policies tailored to local conditions.

Genotyping and molecular investigation of plasmid-mediated carbapenem resistant clinical Klebsiella pneumoniae isolates in Egypt

Klebsiella pneumoniae is a multidrug-resistant nosocomial pathogen. Carbapenem resistance is mediated mainly by enzymes carried on transmissible plasmids causing their dissemination among other members of Enterobacteriaceae. This study aimed to molecularly detect carbapenem resistance genes in K. pneumoniae clinical isolates, genotype them using ERIC-PCR, and investigate plasmid transformation of resistant genes by using ERIC-PCR and sequencing.

Methods

Antimicrobial resistance of sixty carbapenem-resistant K. pneumoniae strains was evaluated by using the disc diffusion method. Five carbapenemases' genes were amplified by conventional PCR. Genotyping was performed using ERIC-PCR. Gene transformation was performed for the five genes to sensitive isolates. Wild and transformed isolates were genetically investigated using ERIC-PCR and sequencing.

Results

Carbapenem resistance in our isolates was associated with high resistance to all tested antibiotics. The 60 K. pneumoniae isolates were divided into 6 resistor types. The prevalence of KPC, IMP, VIM, NDM, and OXA-48 genes were 17%, 63%, 93%, 85% and 100%, respectively. Dendrogram analysis showed 57 distinct patterns, arranged in three clusters. The five genes were transformed successfully into sensitive isolates. ERIC profiles of wild and transformed isolates showed cluster A contained all the wild isolates, and cluster B contained all transformed isolates. Genetic sequences of the 5 genes reflected high genetic similarity with the GenBank reference genes before plasmid transformation; however, a distinguishable decrease of genetic similarity was observed after transformation.

Conclusion

Plasmid-mediated carbapenem resistance in K. pneumoniae and its dissemination among different strains is a real threat to public health.

Molecular Epidemiology of Carbapenem-Resistant Klebsiella pneumoniae in a Tertiary Hospital in Northern China

Background

In recent years, carbapenem-resistant Klebsiella pneumoniae (CRKP) has emerged rapidly in China with the abuse and overuse of antibiotics, and infections caused by CRKP pose a serious threat to global public health safety. The present study aimed to explore the epidemiological characteristics of CRKP isolates in Northern China and to elucidate their drug resistance mechanisms.

Methods

45 CRKP strains were consecutively collected at a teaching hospital from March 1st, 2018 to June 30th, 2018. Antimicrobial susceptibility was determined by the VITEK2 compact system and microbroth dilution method. Polymerase chain reaction (PCR) and sequencing were used to analyze multilocus sequence typing (MLST), drug resistance determinants, and plasmid types. The transfer of resistance genes was determined by conjugation. All statistical analysis was performed using SPSS 22.0 software.

Results

All 45 isolates showed multidrug resistance (MDR). MLST analysis showed ST11 (48.9%, 22/45) was the most frequent type. All of the 45 CRKP isolates contained carbapenemase genes, extended-spectrum β-lactamase (ESBL) genes, and plasmid-mediated quinolone resistance (PMQR) genes. For carbapenemase genes, KPC-2 (93.3%, 42/45) was the main genotype, and followed by GES (37.8%, 17/45) and NDM-1 (11.1%, 5/45). Plasmid typing analysis showed that IncFII and IncFIB were the most prevalent plasmids. The carbapenem resistance rate of K.pneumoniae was 11.4% and ICU was the main CRKP infection source.

Conclusions

ST11 is the most frequent sequence type and KPC-2 is the predominant carbapenemase of CRKP strains in Northern China. KPC-2-ST11 are representative clonal lineages.

The Genetic Characteristics and Carbapenem Resistance Mechanism of ST307 Klebsiella pneumoniae Coharbouring blaCMY-6, blaOXA-48, and a Truncated blaNDM-1

Carbapenem-resistant Klebsiella pneumoniae (CRKP) is a common nosocomial pathogen causing severe infectious diseases, and ST307 CRKP is an emerging clone. In this study, we collected five ST307 CRKP isolates, evaluated their antimicrobial susceptibility using microbroth dilution, and their clonality and population structure by PFGE, cgMLST, and SNP-based phylogenetic analysis. Then, the genome characteristics, such as antimicrobial resistance genes and plasmid profiles, were studied by subsequent genomic analysis. The plasmid transfer ability was evaluated by conjugation, and the carbapenem resistance mechanism was elucidated by gene cloning. The results showed that all five ST307 CRKP isolates harboured blaCMY-6, blaOXA-48, and blaNDM-1; however, the end of the blaNDM-1 signal peptide was interrupted and truncated by an IS10 element, resulting in the deactivation of carbapenemase. The ST307 isolates were closely related, and belonged to the globally disseminated clade. blaOXA-48 and blaNDM-1 were located on the different mobilisable IncL/M- and IncA/C2-type plasmids, respectively, and either the pOXA-48 or pNDM-1 transconjugants were ertapenem resistant. Gene cloning showed that blaCMY-6 could elevate the MICs of carbapenems up to 64-fold and was located on the same plasmid as blaNDM-1. In summary, ST307 is a high-risk clone type, and its prevalence should be given additional attention.

Phenotypic and molecular characterization of extended-spectrum β-lactamase/AmpC- and carbapenemase-producing Klebsiella pneumoniae in Iran

BACKGROUND

The objective of the current study is to evaluate the phenotypic and molecular characterization of ESBL/AmpC- and carbapenemase-producing K. pneumoniae isolates in Iran.

METHODS

From October 2018 until the end of April 2020, different clinical samples were collected and K. pneumoniae isolates were identified using conventional biochemical tests and PCR assay. Antibiotic susceptibility pattern was determined using the Kirby-Bauer disk diffusion method. Modified Hedge Test (MHT) was applied to the identification of carbapenemase-producing K. pneumoniae. ESBL and AmpC-producing K. pneumoniae were detected using Double Disc Test (DDT) and Disc Potentiation Test (DPT), respectively. The presence of carbapenemase, ESBL, and AmpC encoding genes was screened by Polymerase Chain Reaction (PCR) assay.

RESULTS

A total of 100 K. pneumoniae isolates were collected. K. pneumoniae isolates had the highest resistance rate to cefazolin (66%) and cefotaxime (66%). Meropenem and amikacin with sensitivity rates of 76% and 69% were the most effective antimicrobial agents on K. pneumoniae isolates. It was found that 12 (12%), 27 (27%), and 9 (9%) K. pneumoniae isolates were positive in MHT, DDT, and DPT tests, respectively. Among the carbapenemase-encoding genes, bla_OXA-48 (24%) and bla_IMP (13%) genes had the highest frequency, while bla_KPC and bla_GIM genes were not detected among K. pneumoniae isolates. bla_TEM (48%) and bla_CMY (8%) genes had the highest frequency among ESBL and AmpC β-lactamase-encoding genes, respectively.

CONCLUSIONS

It is vital to adopt effective control strategies for K. pneumoniae infections and ensure rapid identification of antibiotic resistance profile.

Detection of intestinal colonization by carbapenem-resistant Enterobacteriaceae (CRE) among patients admitted to a tertiary care hospital in Egypt

Background

The irrational use of carbapenems in the last years lead to the emergence of carbapenem-resistant Enterobacteriaceae (CRE). This study aimed at determining the prevalence of CRE intestinal carriage among admitted patients in a tertiary care hospital in Egypt, to characterize carbapenemase-producing genes and to identify possible risk factors of CRE colonization. One hundred rectal swabs were collected from patients within 48 h of hospital admission. Culture was done on chromogenic media and then identification and antibiotic susceptibility testing were done using Vitek 2 compact system. Carbapenemase production was confirmed by Rapidec Carba NP test and by multiplex PCR for blaOXA-48-like, blaNDM-like, blaVIM-like, blaIMP-like and blaKPC-like.

Results

A total number of 36 CRE isolates were recovered from 28 patients. Thus, the prevalence of CRE colonization was 28%. Escherichia coli (83%), followed by Klebsiella pneumoniae (17%) were the main species. History of recent hospitalization and prior antibiotic intake were statistically significant risk factors predisposing to CRE colonization. Rapidec Carba NP gave positive results in 29/36 CRE isolates, whereas seven isolates gave negative results; six of them harbored blaOXA-48-like. Overall, the blaOXA-48-like was detected in 24/36 (66.7%), followed by blaNDM-like in 11/36 (30.6%) and lastly blaVIM-like in 1/36 (2.8%).

Conclusions

Our findings confirm that CRE colonization is disseminating in our healthcare facility, a fact that should be considered as possible pathogens causing infections in high risk patients. Strict infection control measures should be applied to all CRE carriers at hospital admission and a proper antimicrobial stewardship program should be followed in clinical settings.

Prevalence of Efflux Pump and Porin-Related Antimicrobial Resistance in Clinical Klebsiella pneumoniae in Baghdad, Iraq

Klebsiella pneumoniae is an opportunistic bacterium that causes many infections, including septicemia, pneumonia, urinary tract infection, and liver abscesses. There are many mechanisms for antibiotic resistance and K. pneumonia is considered a multidrug-resistant pathogen. This study aimed to find the correlation between the susceptibility of K. pneumonia to certain antibiotics with the porin-related resistance and pumps mechanisms. In total, two genes that are responsible for porin formation were considered in the current study OmpK-35gene and OmpK-36 gene, in addition to other four genes (CfiaS, CfiaL, MFS, and MdtK genes) related to an efflux pump mechanism of antibiotic resistance. The bacterial resistance was investigated towards five cephalosporins (Cefazolin, Cefoxitin, Ceftazidime, Ceftriaxone, and Cefepime) and two carbapenems (imipenem and ertapenem). Clinical samples, including blood, swabs, and urine, consisting of 20 specimens for each group, were collected from patients who attended three hospitals in Baghdad. The VITEK-2 system and genetic tests (polymerase chain reaction and sequencing) of bacterial isolates were applied to confirm the diagnosis of K. pneumoniae and detect the antibiotic sensitivity profile. The results showed that 51 (85%) and 15 (25%) of the total 60 isolates had positive results for OmpK-35 and Omp-K36 genes, respectively. The MFS and MdtK genes were observed (70-88.3%) in cephalosporin-resistant isolates of K. pneumoniae. There were no significant variations of bacterial resistance genes of antibiotics within the specimen groups. It was concluded that the bacterial resistance of the selected antibiotics was elevated markedly with the loss of the OmpK-36 gene with a high expression of MFS and MdtK genes and a slight minimal occurrence in the new generation of carbapenems. The best antimicrobial agent was ertapenem with a percentage of 0% of resistance in all bacterial isolates.

Global surveillance of antimicrobial resistance and hypervirulence in Klebsiella pneumoniae from LMICs: An in-silico approach

The global emergence of antimicrobial resistance (AMR) among pathogens is a major public health crisis that might soon lead to a post-antibiotic era. Klebsiella pneumoniae, included in the World Health Organization list of critical priority pathogens, is an emerging threat to global health owing to the rapid rise of convergent AMR and hypervirulent strains. Comprehensive epidemiology of AMR-hypervirulent determinants in K. pneumoniae from Low-and Middle-Income Countries (LMICs) is still lacking. As part of rapid risk assessment, an in-silico approach was employed to characterize the AMR and hypervirulence determinants in K. pneumoniae from LMICs. Genomic data of 2432 K. pneumoniae strains were obtained from 33 LMICs representing 4 continents; Asia (n = 12), Africa (n = 18), N. America (n = 2) and Europe (n = 1). All the analysed strains were multiple-drug resistant and 13.6% of them were hypervirulent as well. The co-existence of antibiotic resistant genes conferring concomitant resistance towards life-saving drugs (carbapenems, colistin, fluoroquinolones and fosfomycin) were also observed among the strains, thereby challenging the efficacy of current treatment strategies. The emergence of convergent strains of K. pneumoniae carrying both multi-drug resistance and hypervirulence-associated genes in 12 LMICs is highlighted in this study. Asian region was identified as the major hotspot for convergent strains, especially being confined to 3 countries (India, Pakistan and Vietnam), further exacerbating the situation. This represents a major challenge to disease treatment and public health management in the LMICs. Regular surveillance for emergence of convergence and necessary interventions in the high-risk regions are strongly recommended.

Emergence of Klebsiella pneumoniae ST307 Co-Producing CTX-M with SHV and KPC from Paediatric Patients at Shenzhen Children's Hospital, China

Aim

We investigated the clonal diversity of carbapenemase-producing Klebsiella pneumoniae isolates from the Shenzhen Children’s Hospital, China, and drew conclusions on the clinical and public health impact of these isolates as multidrug-resistant.

Methods

From January 2014 to December 2018, a total number of 36 unique carbapenemase-producing clinical isolates of Klebsiella pneumoniae were collected out of 900 clinical isolates in paediatric patients from the Shenzhen Children’s Hospital, China. After carbapenemase production confirmation, antimicrobial susceptibility, resistance determinants and phylogenetic relationship were determined.

Results

The isolates showed resistance to ceftazidime, ertapenem, ampicillin, cefazolin, ceftriaxone, cefotetan, ticarcillin, cefaclor, cefpodoxime, azlocillin, cefcapene, mezlocillin and ampicillin-sulbactam. Of the 36 Klebsiella pneumoniae carbapenemase genes coding isolates, bla_NDM was the mostly detected 50% (n=18) followed by bla_KPC and bla_IMP 19% (n=7), bla_VIM 17% (n=6), bla_OXA-48-like 8% (n=3) and bla_SME 5% (n=2), whereas extended-spectrum β-lactamase (bla_SHV) was predominantly detected 92% (n=33) followed by bla_CTX-M 53% (n=19) and bla_CMY 28% (n=10). Pulsed-field gel electrophoresis typing showed eight different patterns, and twenty-five distinct sequences types were observed with ST307 being predominantly identified 11% (n=4), followed by ST2407 8% (n=3). Plasmid replicon typing results indicated that IncFIS, IncHI2, IncFIC and IncFIA plasmids carry bla_CTX-M,bla_SHV and bla_NDM genes.

Conclusion

This study reports on the occurrence and spread of carbapenemase and extended-spectrum β-lactamase encoding genes co-existence in sporadic Klebsiella pneumoniae ST307 in paediatric patients from the Shenzhen Children’s Hospital, China.

Bloodstream Infections caused by Klebsiella pneumoniae and Serratia marcescens isolates co-harboring NDM-1 and KPC-2

Carbapenem-resistant Enterobacteriaceae are a worldwide health problem and isolates carrying both bla_KPC-2 and bla_NDM-1 are unusual. Here we describe the microbiological and clinical characteristics of five cases of bloodstream infections (BSI) caused by carbapenem-resistant Klebsiella pneumoniae and Serratia marcescens having both bla_KPC-2 and bla_NDM-1. Of the five blood samples, three are from hematopoietic stem cell transplantation patients, one from a renal transplant patient, and one from a surgical patient. All patients lived in low-income neighbourhoods and had no travel history. Despite antibiotic treatment, four out of five patients died. The phenotypic susceptibility assays showed that meropenem with the addition of either EDTA, phenylboronic acid (PBA), or both, increased the zone of inhibition in comparison to meropenem alone. Molecular tests showed the presence of bla_KPC-2 and bla_NDM-1 genes. K. pneumoniae isolates were assigned to ST258 or ST340 by whole genome sequencing. This case-series showed a high mortality among patients with BSI caused by Enterobacteriae harbouring both carbapenemases. The detection of carbapenemase-producing isolates carrying both bla_KPC-2 and bla_NDM-1 remains a challenge when using only phenotypic assays. Microbiology laboratories must be alert for K. pneumoniae isolates producing both KPC-2 and NDM-1.

Carbapenem-Resistant Klebsiella pneumoniae Osteomyelitis Treated with Ceftazidime-Avibactam in an Infant: A Case Report

Increasing cases of carbapenem-resistant Klebsiella pneumoniae (CR-KP) infections have been observed globally where multi-drug resistance to CR-KP can make the infection difficult to treat. In recent years, the β-lactam/β-lactamase inhibitor, ceftazidime-avibactam (CAZ-AVI), has been developed to treat complicated urinary tract infections and complicated intra-abdominal infections. CAZ-AVI is approved for children over 3-month old but has yet to be investigated for cases of osteomyelitis. Only three case reports exist in literature on the use of CAZ-AVI for CR-KP osteomyelitis in adults. In this report, we present an infant with primary hematogenous osteomyelitis and septic arthritis in the right shoulder following surgical treatment for a heart murmur. Bacterial isolation revealed a strain of CR-KP, which was successfully treated with CAZ-AVI after initial administration of imipenem-based treatments.

Emerging Threat of Multidrug Resistant Pathogens From Neonatal Sepsis

Multidrug-resistant (MDR) pathogens are responsible for a substantial burden of morbidity and mortality from neonatal sepsis; however, data on these sepsis-related pathogens among hospitalized neonates in China are not well characterized. In this study, a total of 240 strains were isolated from four Women and Children's hospitals in Southwest China between 2014 and 2019. Of these included pathogens, 104 (43.33%) were gram-positive bacteria, 129 (53.75%) were gram-negative bacteria, and 7 (2.92%) were fungi. Escherichia coli (E. coli, 34.01%) and Klebsiella pneumoniae (K. pneumoniae, 15.35%) were the main pathogen of neonate bacteremia. ST167 were the most prevalent STs in E. coli and ST11 in K. pneumoniae. Our study found that E. coli (62.71%) was the predominate pathogen of early-onset sepsis, among which 64.86% were MDR. Late-onset sepsis was mainly caused by K. pneumoniae (28.31%) and E. coli (24.78%), with showing that 78.33% of these pathogens were MDR. Notably, the prevalence of EO/LO pathogens were quite different from Indian and south of China. Moreover, we found that bla _CTX-M (42.06%) was most dominant resistant genes with about a third isolates (31.09%) were positive for bla _CTX-M-15. All the carbapenem-resistant K. pneumoniae were positive for NDM-1. Moreover, late-onset sepsis and antibiotic exposure were significantly associated with MDR infection. Emerging multi-resistant pathogens of sepsis posts a serious threat to neonatal outcomes and emphasizes an urgent need to control their further spread.

Molecular Characterization of Carbapenem Resistant Klebsiella pneumoniae in Malaysia Hospital

The emergence of carbapenem-resistant Klebsiella pneumoniae (CRKP) is a great concern, as carbapenems are the last-line therapy for multidrug-resistant Gram-negative bacteria infections. This study aims to report the epidemiology of CRKP in a teaching hospital in Malaysia based on the molecular genotypic and clinical characteristics of the isolates. Sixty-three CRKP strains were isolated from a tertiary teaching hospital from January 2016 until August 2017. Carbapenemase genes were detected in 55 isolates, with bla_OXA-48 (63.5%) as the predominant carbapenemase gene, followed by bla_NDM (36.5%). At least one porin loss was detected in nine isolates. Overall, 63 isolates were divided into 30 clusters at similarity of 80% with PFGE analysis. Statistical analysis showed that in-hospital mortality was significantly associated with the usage of central venous catheter, infection or colonization by CRKP, particularly NDM-producers. In comparison, survival analysis using Cox proportional hazards regression identified a higher hazard ratio for patients with a stoma and patients treated with imipenem but a lower hazard ratio for patients with NDM-producing CRKP. OXA-48 carbapenemase gene was the predominant carbapenemase gene in this study. As CRKP infection could lead to a high rate of in-hospital mortality, early detection of the isolates was important to reduce their dissemination.

Analysis of Pathogen Distribution and Its Antimicrobial Resistance in Bloodstream Infections in Hospitalized Children in East China, 2015-2018

This study analyzed the pathogen distribution in bloodstream-infected (BSI) children hospitalized in Shandong Province from 2015 to 2018, to identify prevention strategies and select empiric antimicrobial therapy for BSI in children. Blood sample data from 14 107 children from 162 hospitals of Shandong Province were obtained from the China Antimicrobial Resistance Surveillance System and analyzed with WHONET 5.6 software. The results of the blood culture test showed the growth of 70.6% Gram-positive and 29.4% Gram-negative bacteria. Of the 14 107 blood isolates, 59.3% were collected from males and 40.7% were from females. Coagulase-negative staphylococci (47.1%) were the most commonly distributed pathogens. The distribution of pathogens varied according to age group and season. All Staphylococcus isolates were susceptible to vancomycin, teicoplanin and linezolid. Clinically, significant declines in penicillin-resistant Streptococcus pneumonia and carbapenem-resistant Escherichia coli were observed during the study period; however, detection rates of carbapenem-resistant Klebsiella pneumoniae increased over time (p < 0.05). Empiric antimicrobial therapy should be prescribed according to corresponding regional pediatric antimicrobial-resistant data.

Detection of carbapenem-resistant Klebsiella pneumoniae strains harboring carbapenemase, beta-lactamase and quinolone resistance genes in intensive care unit patients

Aim: Carbapenem-resistant Klebsiella pneumoniae (CR-Kp) strains are important nosocomial pathogens worldwide. In this study, we aimed to reveal the antibiotic resistance of clinical CR-Kp strains and determine the presence of KPC, OXA-48, VIM and IMP carbapenemase genes. CTX-M-1, TEM-1, SHV-1 extended-spectrum beta-lactamase (ESBL) genes, qnrA, qnrB, qnrS plasmid-mediated quinolone resistance genes and sul1 and sul2 sulfonamide resistance genes provided molecular epidemiological data.

Methods: A total of 175 K. pneumoniae strains were isolated from clinical samples of patients hospitalised in an intensive care unit (ICU) betweent April and October 2017. The strains were identified with conventional methods, with VITEK 2 (BioMerieux, France) and MALDI-TOF MS (Bruker, USA). Antimicrobial susceptibilities were tested using the disc-diffusion method and E-test (BioMerieux, France). Antimicrobial resistance genes were investigated via real-time PCR in strains identified as CR-Kp.

Results: High frequencies of bla_TEM-1 (86.36%), bla_SHV-1 (86.36%), and bla_CTX-M-1 (95.45%) genes were found in CR-Kp strains. Morever, all three ESBL genes coexisted in 77.3% of all strains. bla_KPC was detected in 12 (54.55%) of the strains, and 4 of them which had an MIC> 16 μg/mL to imipenem showed bla_OXA-48 positivity as well. The qnrS gene determinant (86.36%) had the highest frequency, and strains carrying qnrA showed higher MICs for ciprofloxacin.

Conclusion: CR-Kp strains are able to develop different antimicrobial resistance patterns according to regional changes in antimicrobial therapeutic policies. Thus, it is important to monitor the regional molecular epidemiological data for efficient treatment.

Mutation of kvrA Causes OmpK35 and OmpK36 Porin Downregulation and Reduced Meropenem-Vaborbactam Susceptibility in KPC-Producing Klebsiella pneumoniae

Meropenem-vaborbactam resistance in Klebsiella pneumoniae isolates is associated with loss-of-function mutations in the OmpK35 and OmpK36 porins. We identify two previously unknown loss-of-function mutations that confer cefuroxime resistance in K. pneumoniae isolates. The proteins lost were NlpD and KvrA; the latter is a transcriptional repressor that controls capsule production. We demonstrate that KvrA loss reduces OmpK35 and OmpK36 porin production, which confers reduced susceptibility to meropenem-vaborbactam in a KPC-3-producing K. pneumoniae isolate.

Structural Genomics of repA, repB 1-Carrying IncFIB Family pA1705-qnrS, P911021-tetA, and P1642-tetA, Multidrug-Resistant Plasmids from Klebsiella pneumoniae

BACKGROUND

Multidrug-resistant plasmids carrying replication genes have been widely present in various strains of Klebsiella pneumoniae. RepA and repB1 were found in plasmids belong to the IncFIB, but their detailed structural and genomic characterization was not reported yet. This is the first study that delivers structural and functional insights of repA- and repB1-carrying IncFIB plasmids.

METHODS

Klebsiella pneumoniae strains A1705, 911021, and 1642 were isolated from the human urine samples and bronchoalveolar fluids collected from different hospitals of China. Antibacterial susceptibility and plasmid transfer ability were tested to characterize the resistant phenotypes mediated by the pA1705-qnrS, p911021-tetA, and p1642-tetA. The complete nucleotide sequences of these plasmids were determined through high-throughput sequencing technology and comparative genomic analyses of plasmids belong to the same incompatibility group were executed to extract the genomic variations and features.

RESULTS

The pA1705-qnrS, p911021-tetA, and p1642-tetA are defined as non-conjugative plasmids, having two replication genes, repA and repB1 associated with IncFIB family, and unknown incompatible group, respectively. Comparative genomic analysis revealed that relatively small backbones of IncFIB plasmids integrated massive accessory module at one "hotspot" that was located between orf312 and repB1. These IncFIB plasmids exhibited the distinct profiles of accessory modules including one or two multidrug-resistant regions, many complete and remnant mobile elements comprising integrons, transposons and insertion sequences. The clusters of resistant genes were recognized in this study against different classes of antibiotics including β-lactam, phenicol, aminoglycoside, tetracycline, quinolone, trimethoprim, sulfonamide, tunicamycin, and macrolide. It has been observed that all resistant genes were located in multidrug resistance regions.

CONCLUSION

It is concluded that multidrug-resistant repA and repB1-carrying IncFIB plasmids are a key source to mediate the resistance through mobile elements among Klebsiella pneumoniae. Current findings provide a deep understanding of horizontal gene transfer among plasmids of the IncFIB family via mobile elements that will be utilized in further in vitro studies.

The complex genetic region conferring transferable antibiotic resistance in multidrug-resistant and extremely drug-resistant Klebsiella pneumoniae clinical isolates

Antibiotic resistance due to transferable resistance genes is one of the most important concerns in Klebsiella pneumoniae isolated from nosocomial infections. Eighty-eight K. pneumoniae isolates were confirmed through biochemical methods. In addition, antimicrobial susceptibility testing was performed using a disc-diffusion method. Extended-spectrum β-lactamase production among the isolates was screened using a double-disc synergism test, and the resistance genes were identified using PCR. The eight loci for multiple-locus variable number tandem repeat analysis (MLVA) genotyping were selected along with the primers. According to our findings, neomycin (5; 5.6%) and carbapenems (10; 11.3%) showed the most remarkable inhibitory effect but co-trimoxazole (46; 52.2%) was the least effective antibiotic against K. pneumoniae isolates. bla _CTX-M-1 , qnrA, qnrB, qnrS, intI, intII, aac3 and aac6 were detected in 30 (34%), 5 (5.6%), 29 (32.9%), 23 (26.1%), 88 (100%), 72 (81.8%), 26 (29.5%) and 28 (31.8%) of the 88 isolates, respectively. But none of the K. pneumoniae isolates expressed the intIII gene. Using MLVA, 23 MLVA types and eight clusters were identified. Extended-spectrum β-lactamase-producing K. pneumoniae isolates were classified into two clonal complexes. Effective strategies for infection control should be applied to monitor and control the spread of multidrug-resistant isolates by the resistance genes located on the mobile genetic elements.

The Inc FII Plasmid and its Contribution in the Transmission of blaNDM-1 and blaKPC-2 in Klebsiella pneumoniae in Egypt

The emergence of bla_KPC-2 and bla_NDM-1 producing Klebsiella pneumoniae represents a great problem in many Egyptian hospitals. One hundred and twenty-six K. pneumoniae isolates from patients admitted to Assiut University Hospital were identified by an API20E kit. Carbapenemase-producing K. pneumoniae (CPKP) was detected by the modified carbapenem inactivation method (mCIM), the EDTA-modified carbapenem inactivation method (eCIM), and an E-test. Based on the polymerase chain reaction, all isolates were negative for bla-_VIM-1 and bla-_IMP-1, fifteen of these isolates were positive for both bla_KPC-2 and bla_NDM-1, two isolates were positive for bla_KPC-2 only, and twenty-eight isolates were positive for bla-_NDM-1 only. Although one isolate was positive for the string test, all CPKP isolates were negative for capsular genes. Only 71.1% of CPKP transferred their plasmids to their corresponding transconjugants (E. coli J53). The resistance patterns of the clinical isolates and their transconjugates were similar, except for 12 isolates, which showed differences with their transconjugates in the resistance profile of four antibiotics. Molecular typing of the plasmids based on replicon typing showed that Inc FIIK and FII plasmids predominated in isolates and their transconjugants carrying bla_KPC-2 and/or bla_NDM-1. Conjugative Inc FII plasmids play an important role in the spread of CPKP, and their recognition is essential to limit their spread.

New Delhi Metallo-β-Lactamase 1-Producing Klebsiella pneumoniae ST719 Isolated from a Neonate in China

The spread of carbapenem-resistant Klebsiella pneumoniae has become a significant problem for public health in recent years. In this study, we reported a New Delhi metallo-β-lactamase 1 (NDM-1)-producing K. pneumoniae strain KP14003 from a neonate in Beijing, China. Whole-genome sequencing was performed. The strain belonged to sequence type ST719. Coexistence of bla_NDM-1 and bla_SHV-12 was found on a self-transferable plasmid, which had a typical IncX3 backbone. The horizontal transfer of bla_NDM-1 was associated with Tn125 followed by possible transposition events. Other class A extended-spectrum β-lactamase genes (bla_SHV-27 and bla_TEM-1) were also identified on chromosome or plasmid. The dissemination of NDM-1-producing K. pneumoniae causes great challenges to the treatment of clinical infections. Effective actions need to be taken to control the further spread of this pathogen.

Proteomics approach to understand bacterial antibiotic resistance strategies

Introduction: The understanding of novel antibiotic resistance mechanisms is essential to develop strategies against antibiotic-resistant pathogens, which has become an urgent task due to the worldwide emergence of antibiotic resistance. Areas covered: In this review, the authors summarize the recent progress on antibiotic resistance caused by lab-evolved bacteria and clinical multidrug-resistant bacterial pathogens from the proteomics perspective. Expert opinion: Proteomics provides a new platform for a comprehensive understanding of change in protein pathways that are engaged in antibiotics resistance, which is different from a genetic view that focuses on the role of an individual gene or protein. Further work is required to understand why and how the involved pathways are integrated for surviving antibiotic-mediated killing, to use other OMICs for better comprehension of antibiotic resistance mechanisms, and to develop reprogramming proteomics, which reverts an 'antibiotic resistance proteome' to an 'antibiotic sensitive or antibiotic sensitive-like' proteome, for the control of antibiotic-resistant pathogens.

Treatment with andrographolide sulfonate provides additional benefits to imipenem in a mouse model of Klebsiella pneumoniae pneumonia

Klebsiella pneumoniae is a primary cause of community-acquired and nosocomial respiratory infections, and K. pneumoniae resistance to the current treatment approach with carbapenem is worsening. Andrographolide is a natural diterpenoid from Andrographis paniculata that was shown to exert anti-inflammatory activity. We herein show that pretreatment with a water-soluble andrographolide sulfonate significantly attenuate lung injury and infiltration of inflammatory cells. Interestingly, mice receiving combined treatment with andrographolide sulfonate displayed perfect survival rate than the mice treatment with imipenem alone, and monocyte chemotactic protein 5 (MCP-5) level was decreased further. These findings suggest that andrographolide sulfonate could as a potential synergist for antibiotic treatment of bacteria-induced inflammation.

Shifting trends and age distribution of ESKAPEEc resistance in bloodstream infection, Southwest China, 2012-2017

Background

ESKAPEEc contribute to a majority of bloodstream infections (BSIs) and their antibiogram have changed overtime, while data concerning about these alterations are lacking in China. Added that a paucity of studies referred to ESKAPEEc in pediatric BSIs, our study aimed to demonstrate the longitudinal alterations of ESKAPEEc distribution and antibiogram in adult and pediatric BSIs in Southwest China.

Methods

A multicenter retrospective surveillance study was launched from 2012 to 2017. Data of China Antimicrobial Resistance Surveillance System (CARSS) was analyzed by Whonet 5.6 and Graphpad Prism 6 Software. Chi-square test or Fisher’s exact test was used to examine and compare temporal changes.

Results

A total of 32,259 strains was isolated, with 17.4% from pediatric BSIs. ESKAPEEc contributed to 58.67% (18,924/32,259) of BSIs, with 65.3% of adult BSIs and 27.2% of pediatric BSIs. Escherichia coli (E. coli) and Klebsiella pneumoniae (K. pneumoniae) were the two predominant species. Carbapenem resistance was prevalent in 0.76, 4.60, 9.47,13.66, 59.47% of E. coli, K. pneumoniae, Enterobacter cloacae, Pseudomonas aeruginosa (P. aeruginosa) and Acinetobacter baumannii (A. baumannii), respectively. The proportions of methicillin-resistant Staphylococcus aureus (MRSA) and vancomycin-resistant Enterococcus faecium (VREFM) were 28.91% and 2.20%, respectively. Between 2012-2014 and 2015–2017, E. coli and K. pneumonia showed significantly increased resistance rates to imipenem but decreased to ceftriaxone and ceftazidime, while A. baumannii exhibited reduced resistances to almost all the beta-lactams tested. The prevalence of antimicrobial resistance to most of agents against Gram-positive ESKAPEEc did not significantly varied during the same timeframe. In comparison with those from adult BSIs, K. pneumoniae from pediatric BSIs exhibited high resistance rates to all the beta-lactams tested, especially to carbapenems (12.79% vs 3.87%), while A. baumannii showed low resistance rates to all the agents.

Conclusions

Ongoing burden of ESKAPEEc in BSIs and increasing trend of imipenem resistance in E. coli and K. pneumoniae call for continued surveillance. Carbapenems are still active against Gram-negative ESKAPEEc, except for A. baumannii and vancomycin or linezolid is still effective against Gram-positive ESKAPEEc. Carbapenem-resistant K. pneumoniae in children and carbapenem-resistant A. baumannii in adults necessitate effective antimicrobial strategies in consideration of age stratification.

Identification and Characterization of NDM-1-producing Hypervirulent (Hypermucoviscous) Klebsiella pneumoniae in China

Background

Carbapenem-resistant hypervirulent (hypermucoviscous) Klebsiella pneumoniae (CR-HMKP) poses a significant public health challenge. We investigated its epidemiology and molecular characteristics in a tertiary care hospital in eastern China.

Methods

CR-HMKP were identified among 106 non-duplicated carbapenem-resistant K. pneumoniae isolates (from June 2013 to September 2017) using the string test. The pulsotype (PT) and sequence type (ST) of CR-HMKP isolates were determined using pulsed-field gel electrophoresis and multilocus sequence typing. Resistance determinants, capsular serotypes, and virulence genes were detected by PCR and sequencing. Representative isolates from each PT were selected, and their virulence phenotypes were established using the serum killing and Galleria mellonella lethality assays.

Results

Of the 106 isolates, 13 (12.3%) were CR-HMKP. Seven were positive for bla_NDM-1 and shared the same genotype (PT5/ST1764); the others were positive for bla_KPC-2, belonged to ST11, and were divided into four different PTs. The serotype of all bla_NDM-1-positive isolates was K64, while that of bla_KPC-2-positive isolates were K47 (N=4) and K64 (N=2). The NDM-1-producing HMKP isolates were positive for aerobactin, exhibited high serum resistance, and elicited significantly increased larval mortality compared with the other isolates. All patients had received invasive treatment prior to infection by NDM-1-producing HMKP. The infections occurred between July and August 2016 and were hospital-acquired.

Conclusions

NDM-1-producing HMKP ST1764 isolates were identified; this is the first report worldwide on an outbreak of nosocomial infection caused by these isolates. Effective surveillance and strict infection control strategies should be implemented to prevent CR-HMKP dissemination.

Epidemiologic analysis and control strategy of Klebsiella pneumoniae infection in intensive care units in a teaching hospital of People's Republic of China

BACKGROUND

Klebsiella pneumoniae (KP) is the most common pathogen isolated in intensive care units (ICUs) and the most frequently encountered carbapenemase-producing Enterobacteriaceae. Increasing antimicrobial drug resistance, especially in carbapenem-resistant KP (CRKP), can limit the choice of antibiotics used for the treatment of infectious diseases and further poses a negative impact on patient outcome. However, the reason behind this increasing resistance is not well known.

PATIENTS AND METHODS

A retrospective analysis of laboratory records and clinical cases of KP infection in the ICUs of a hospital from January 2013 to December 2017 was conducted. The disk diffusion method and double-paper synergy test were used to test drug sensitivity for extended-spectrum β-lactamase (ESBL) detection. WHONET5.6 and SPSS 21.0 software were used for statistical analysis.

RESULTS

A total of 64.8% (570/847) of patients with KP infection were older than 60 years. The lower respiratory tract was the main infection site, accounting for 70.84% (600/847); the highest rate of ICU admission was for neurosurgery, accounting for 28.69% (243/847). Some 444 multidrug-resistant KP strains were detected, including 69 CRKP and 299 ESBL-producing strains. In the past 5 years, the resistance rate of detected strains to common antibiotics increased to various degrees, particularly carbapenem-resistant strains which increased from 4.76% (9/189) in 2013 to 16.00% (28/175) in 2017. All carbapenem-resistant isolates were resistant to β-lactam antibiotics, and no isolates were resistant to tigecycline.

CONCLUSION

CRKP and ESBLKP prevalence and resistance rates gradually increased in our ICUs in the past 5 years. The reasons for this are manifold. Regular surveillance of resistance, rational use of antibiotics, and other effective infection control measures need to be strengthened to slow down the production of multidrug-resistant bacteria and prevent their spread in ICU settings.

Endemic dissemination of different sequence types of carbapenem-resistant Klebsiella pneumoniae strains harboring bla NDM and 16S rRNA methylase genes in Kerman hospitals, Iran, from 2015 to 2017

Introduction

The emergence and spread of Klebsiella pneumoniae strains resistant to multiple antimicrobial agents are considered as a serious challenge for nosocomial infections.

Materials and methods

In this study, 175 nonrepetitive clinical isolates of K. pneumoniae were collected from hospitalized patients in Kerman, Iran. Extended-spectrum β-lactamases (ESBLs), AmpC, and carbapenemase-producing isolates were recognized by phenotypic methods. The resistance genes including efflux pumps oqxA/oqxB, 16S rRNA methylase, ESBL, AmpC, and carbapenemase were detected by PCR-sequencing method. Molecular typing was performed by enterobacterial repetitive intergenic consensus-PCR and multilocus sequence typing methods among bla_NDM-positive isolates.

Results

Thirty-seven (21.14%) isolates along with sequence types (STs): ST43, ST268, ST340, ST392, ST147, and ST16 were harbored bla_NDM. ST43 in 2015 and ST268 during 2016–2017 were the most frequent STs among New Delhi metallo-beta-lactamase (NDM)-positive isolates. We found the distribution of some isolates with bla_NDM, bla_CTX-M, bla_SHV, bla_OXA, bla_TEM, bla_CMY, rmtC, and oqxA/oqxB. Enterobacterial repetitive intergenic consensus-PCR represented seven clusters (A–G) plus four singletons among NDM-positive isolates. This study provides the first report of bla_NDM-1-positve K. pneumoniae along with ST268 as well as the spread of nosocomial infections with six different STs harboring bla_NDM-1 and other resistance genes in hospital settings especially neonatal intensive care unit.

Conclusion

The dissemination of various clones of NDM-producing K. pneumoniae can contribute to increase the rate of their spread in health care settings. Therefore, molecular typing and detection of resistance genes have an important role in preventing and controlling infection by limiting the dissemination of multidrug-resistant isolates.

A Novel Target Pathogen Identification and Tracking System Using Capillary Electrophoresis-Random Amplified Polymorphic DNA

Rapid and accurate identification of pathogen is a major quarantine strategy for outbreak prevention. We used capillary electrophoresis-random amplified polymorphic DNA (CE-RAPD) to generate highly discriminatory pathogen profiles, reduced batch effects between profiles by novel normalization procedure and pattern of technical repeats, followed by target similarity evaluation using target identification score (TIS). A full target signature contains several patterns. TIS system was optimized by training set isolates that included three species, and validated using two hundred clinical Klebsiella pneumoniae isolates. Hierarchical clustering analysis showed CE-RAPD profiles arrange clusters according to the species or the source. Moreover, samples with similar profile may display similar antibiotic susceptibility. By using a signature of four patterns, the TIS system could accurately identify target among different isolates. The variation between isolates may be caused by small change in genome. TIS system provides a standardized tool for building of outbreak firewall and facilitate data exchange.

Epidemiology of and risk factors for infection with extended-spectrum β-lactamase-producing carbapenem-resistant Enterobacteriaceae: results of a double case-control study

Purpose

Carbapenem-resistant Enterobacteriaceae (CRE) have been increasingly reported worldwide and pose a serious public threat, but the clinical significance of extended-spectrum β-lactamase (ESBL) production in CRE is not well established.

Patients and methods

A retrospective case–case–control study was conducted to identify the clinical characteristics of patients with ESBL-CRE. The susceptibility of isolates obtained from these patients was assessed. The detection of ESBL and carbapenemase-related genes was performed by PCR methods. Predictors of 30-day mortality in patients with ESBL-CRE infection were also identified in our study.

Results

A total of 149 patients with CRE infection caused by Enterobacter cloacae (n=74), Escherichia coli (n=38), and Klebsiella pneumoniae (n=37) were identified in Chongqing, Southwestern China, between January 2011 and December 2014. Of the 35 isolates detected with carbapenemase-related genes, 16 isolates had New Delhi metallo-β-lactamase (NDM), nine isolates had K. pneumoniae carbapenemase (KPC), seven isolates had imipenemase (IMP), and four isolates had oxacillinase (OXA)-1. One strain of enterobacter cloacae carried both NDM-1 and IMP-8 genes. ESBL isolates included the genes CTX-M (72/149), SHV (64/149), and TEM (54/149). All ESBL-CRE isolates exhibited ertapenem resistance, and the rate of cephalosporin resistance was relatively high in general. Independent risk factors for infection with ESBL-CRE included previous exposure to β-lactam antibiotics, transfer from another hospital, and some underlying diseases. In addition, solid tumors, hypoalbuminemia, and central venous catheters were independent predictors of mortality in patients with ESBL-CRE infection.

Conclusion

Physicians should understand the peculiar predictors for the identification of these organisms among high-risk patients.

Carbapenem-resistant and cephalosporin-susceptible Pseudomonas aeruginosa: a notable phenotype in patients with bacteremia

Purpose

Pseudomonas aeruginosa is recognized as a major cause of severe and potentially life-threatening infection. However, P. aeruginosa isolates with the phenotype of being carbapenem resistant and cephalosporin susceptible (Carb-R/Ceph-S) have not been thoroughly characterized to date. The aim of this study was to assess the mechanisms, risk factors, and clinical impact of Carb-R/Ceph-S P. aeruginosa bacteremia on mortality.

Patients and methods

We conducted a retrospective case-case-control study of the risk factors and clinical outcomes of hospitalized patients with Carb-R/Ceph-S P. aeruginosa bacteremia from 2011 to 2017 in Chongqing, China. Case patients infected with Carb-R/Ceph-S P. aeruginosa, carbapenem-susceptible and cephalosporin-susceptible (Carb-S/Ceph-S) P. aeruginosa, and controls with no P. aeruginosa bacteremia were compared at a ratio of 1:1:2. Real-time reverse transcription polymerase chain reaction was performed to assess resistance mechanisms. A multivariate logistic regression model was performed to investigate several potential predictors for mortality.

Results

We collected 63 Carb-R/Ceph-S P. aeruginosa isolates during the study period. None of these isolates possessed carbapenemase or extended-spectrum β-lactamase-encoding genes. The overall 30-day mortality rate was 27.0%. Real-time reverse transcription polymerase chain reaction analysis showed that an overexpression of efflux systems and decreased expression of OprD were associated with Carb-R/Ceph-S P. aeruginosa. Multivariate analysis indicated that 30-day readmission, central venous catheters, and exposure to carbapenems were unique independent predictors for acquiring Carb-R/Ceph-S P. aeruginosa bacteremia. Additionally, hematologic malignancy was a peculiar predictor for Carb-S/Ceph-S P. aeruginosa bacteremia. Notably, total parenteral nutrition was the only common factor of both Carb-R/Ceph-S and Carb-S/Ceph-S groups compared to controls. In a multivariate analysis for the outcome, intensive care unit admission and septic shock were identified as the independent predictors for mortality.

Conclusion

Our findings can potentially improve the ability of physicians to identify the high-risk patients, and carbapenems were noted to potentially increase the risk of Carb-R/Ceph-S P. aeruginosa. Additionally, cephalosporin should be considered a valuable therapeutic option for such cases of bacteremia.

Whole genome sequence revealed the fine transmission map of carbapenem-resistant Klebsiella pneumonia isolates within a nosocomial outbreak

Background

Carbapenem-resistant Klebsiella pneumoniae (CRKP) is a major cause of nosocomial infections worldwide. The transmission route of CRKP isolates within an outbreak is rarely described. This study aimed to reveal the molecular characteristics and transmission route of CRKP isolates within an outbreak of nosocomial infection.

Methods

Collecting case information, active screening and targeted environmental monitoring were carried out. The antibiotic susceptibility, drug-resistant genes, molecular subtype and whole genome sequence of CRKP strains were analyzed.

Results

Between October and December 2011, 26 CRKP isolates were collected from eight patients in a surgical intensive care unit and subsequent transfer wards of Beijing Tongren hospital, China. All 26 isolates harbored bla_KPC-2, bla_SHV-1, and bla_CTX-M-15 genes, had the same or similar pulsed-field gel electrophoresis patterns, and belonged to the sequence type 11 (ST11) clone. By comprehensive consideration of genomic and epidemiological information, a putative transmission map was constructed, including identifying one case as an independent event distinct from the other seven cases, and revealing two transmissions starting from the same case.

Conclusions

This study provided the first report confirming an outbreak caused by K. pneumoniae ST11 clone co-harboring the bla_KPC-2, bla_CTX-M-15, and bla_SHV-1 genes, and suggested that comprehensive consideration of genomic and epidemiological data can yield a fine transmission map of an outbreak and facilitate the control of nosocomial transmission.