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IntroductionThe emergence of multidrug-resistant Pseudomonas aeruginosa poses a global threat, but the distribution and resistance profiling are unclear, especially in young children. Infections due to P. aeruginosa are common, associated with high mortality, and increasingly β-lactam drug resistant.MethodsWe studied the molecular epidemiology and antibiotic resistance mechanisms in 294 clinicalisolates of P. aeruginosa from a pediatric hospital in China. Non-duplicate isolates were recovered from clinical cases and were identified using an API-20 kit followed by antimicrobial susceptibility testing using the VITEK®2 compact system (BioMerieux, France) and also by broth dilution method. In addition, a double-disc synergy test for the ESBL/E-test for MBL was performed. The presence of beta-lactamases, plasmid types, and sequence types was determined by PCR and sequencing.ResultsFifty-six percent (n = 164) of the isolates were resistant to piperacillin–tazobactam, followed by cefepime (40%; n = 117), ceftazidime (39%; n = 115), imipenem (36%; n = 106), meropenem (33%; n = 97), and ciprofloxacin (32%; n = 94). Forty-two percent (n = 126) of the isolates were positive for ESBL according to the double-disc synergy test. The blaCTX-M-15 cephalosporinase was observed in 32% (n = 40/126), while 26% (n = 33/126) werepositive for blaNDM-1 carbapenemase. Aminoglycoside resistance gene aac(3)IIIawas observed in 16% (n = 20/126), and glycylcyclines resistance gene tet(A) was observed in 12% (n = 15/126) of the isolates. A total of 23 sequence types were detected, including ST1963 (12%; n = 16), followed by ST381 (11%; n = 14), ST234 (10%; n = 13), ST145 (58%; n = 10), ST304 (57%; n = 9), ST663 (5%; n = 7), and a novel strain. In ESBL-producing P. aeruginosa, 12 different Incompatibility groups (Inc) were observed, the most common being IncFI, IncFIS, and IncA/C. The MOBP was the most common plasmid type, followed by MOBH, MOBF, and MOBQ.DiscussionOur data suggest that the spread of antibiotic resistance is likely due toclonal spread and dissemination of different clinical strains of P. aeruginosa harbouring different plasmids. This is a growing threat in hospitals particularly in young children which needs robust prevention strategies.

An HIV outbreak investigation during 2017-2018 in Unnao District, Uttar Pradesh, India, unearthed high prevalence of hepatitis C virus (HCV) antibodies among the study participants. We investigated these HCV infections by analyzing NS5B and core regions. We observed no correlation between HIV-HCV viral loads and clustering of HCV sequences, regardless of HIV serostatus. All HCV isolates belonged to genotype 3a. Monophyletic clustering of isolates in NS5B phylogeny indicates emergence of the outbreak from a single isolate or its closely related descendants. The nucleotide substitution rate for NS5B was 6 × 10

Sandip Patil,1– 3 Hongyu Chen,4 Chunna Guo,4 Xiaoli Zhang,3 Pei-Gen Ren,1 Ngiambudulu M Francisco,5 Feiqiu Wen2,3 1Shenzhen Institute of Advanced Technology, Shenzhen University Town, Shenzhen, Guangdong Province, People’s Republic of China; 2Department of Haematology and Oncology, Shenzhen Children’s Hospital, Shenzhen, Guangdong Province, People’s Republic of China; 3Paediatric Research Institute, Shenzhen Children’s Hospital, Shenzhen, Guangdong Province, People’s Republic of China; 4Department of Laboratory Medicine, Shenzhen Children’s Hospital, Shenzhen, Guangdong Province, People’s Republic of China; 5Grupo de Investigação Microbiana e Imunológica, Instituto Nacional de Investigação em Saúde (National Institute for Health Research), Luanda, AngolaCorrespondence: Feiqiu WenDepartment of Haematology and Oncology, Shenzhen Children’s Hospital, Shenzhen, Guangdong Province, People’s Republic of ChinaTel +86 18938690333Fax +86-755 83009888Email fwen62@163.comAim: 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, blaNDM was the mostly detected 50% (n=18) followed by blaKPC and blaIMP 19% (n=7), blaVIM 17% (n=6), blaOXA-48-like 8% (n=3) and blaSME 5% (n=2), whereas extended-spectrum β-lactamase (blaSHV) was predominantly detected 92% (n=33) followed by blaCTX-M 53% (n=19) and blaCMY 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 blaCTX-M, blaSHV and blaNDM 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.Keywords: Klebsiella pneumoniae, carbapenemase, ESBLs, antimicrobial susceptibility, molecular characterization

Hongyu Chen,1 Huirong Mai,2 Bruno Lopes,3 Feiqiu Wen,2 Sandip Patil2,4 1Department of Laboratory Medicine, Shenzhen Children’s Hospital, Shenzhen, Guangdong, 518038, People’s Republic of China; 2Department of Haematology and Oncology, Shenzhen Children’s Hospital, Shenzhen, Guangdong, 518038, People’s Republic of China; 3Department of Microbiology, School of Medicine, Medical Sciences and Nutrition, University of Aberdeen, Aberdeen, UK; 4Paediatric Research Institute, Shenzhen Children’s Hospital, Shenzhen, Guangdong, 518038, People’s Republic of ChinaCorrespondence: Sandip Patil, Department of Haematology and Oncology, Shenzhen Children’s Hospital, Shenzhen, Guangdong, 518038, People’s Republic of China, Tel +86-18813934471, Fax +86-755-83008283, Email sandippatil1309@yahoo.com Feiqiu Wen, Department of Haematology and Oncology, Shenzhen Children’s Hospital, Shenzhen, Guangdong, 518038, People’s Republic of China, Tel +86-18938690333, Fax +86-755-83009888, Email fwen62@163.comBackground: The rising resistance to carbapenems in Gram-negative bacteria worldwide poses a major clinical and public health risk. This study aimed to characterise carbapenem- and colistin-resistance genes, blaNDM-1 and mcr-1 located on IncX4 plasmid in MDR Pseudomonas aeruginosa, isolated from paediatric patients undergoing chemotherapy as a result of leukaemia.Methods: In this study, six carbapenem-resistant strains of P. aeruginosa were isolated from two paediatric patients under chemotherapy treatment (1.8 years old female and 2.1 years male) from the Shenzhen Hospital, China, in the year 2019. Isolates were screened for conventional antibiotics such as tobramycin, cefepime, imipenem, and ciprofloxacin in additional colistin by using the broth dilution method. Furthermore, resistance determinants: mcr-1, blaNDM-1, blaKPC-1, and blaGES were screened using PCR and sequencing followed by multi-locus sequence typing. The horizontal gene transfer and location of mcr-1 and blaNDM-1 were determined by a liquid mating assay. In addition, Incompatibility type (Inc), PCR-based replicon type, and subgroup (MOB) of plasmid were studied.Results: The screening for conventional antibiotics isolates showed 100% resistance to all the tested antibiotics except tobramycin. All isolates harboured carbapenemase encoding blaNDM-1, of which three also had mcr-1 located on a single IncX4 transferable plasmid. MLST typing revealed that four strains had a novel (new) STs type, while two belonged to ST1966.Conclusion: This study identified for the first time colistin- and carbapenem-resistant MDR P. aeruginosa in paediatric patients with leukaemia in Shenzhen, China. It highlights the need for continuous surveillance in high-risk clones of MDR P. aeruginosa. Prudent use of antibiotics based on local antimicrobial susceptibility and clinical characteristics can help in reducing mortality in immunocompromised patients.Keywords: mcr-1, blaNDM-1, Pseudomonas aeruginosa, leukaemia patients

Sandip Patil,1,2 Xiaorong Liu,2 Hongyu Chen,3 Ngiambudulu M Francisco,4 Feiqiu Wen,1,2 Yixin Chen5,6 1Department of Haematology and Oncology, Shenzhen Children’s Hospital, Shenzhen, Guangdong, 518038, People’s Republic of China; 2Paediatric Research Institute, Shenzhen Children’s Hospital, Shenzhen, Guangdong, 518038, People’s Republic of China; 3Department of Laboratory Medicine, Shenzhen Children’s Hospital, Shenzhen, Guangdong, 518038, People’s Republic of China; 4Grupo de Investigação Microbiana e Imunológica, Instituto Nacional de Investigação em Saúde (National Institute for Health Research), Luanda, 3635, Angola; 5Department of Oncology, Shenzhen People’s Hospital, The Second Clinical Medical College, Jinan University, Shenzhen, Guangdong, 518000, People’s Republic of China; 6Department of Oncology, The First Affiliated Hospital, Southern University of Sciences and Technology, Shenzhen, Guangdong, 518000, People’s Republic of ChinaCorrespondence: Yixin Chen, Department of Oncology, Shenzhen People’s Hospital, The Second Clinical Medical College, Jinan University, Guangdong, 518000, People’s Republic of China, Fax +86 755-22942763 Email yixinchen2013@126.comBackground: Since 2015, plasmid-borne mcr-1 has been reported in various bacterial strains in the clinical setting globally. However, the transmission mechanisms of this gene in Salmonella are not well defined. This study aimed to characterize the genomic features of a Salmonella enterica ST34 isolate, which carried a mcr-1, mapped to a carbapenemase and extended spectrum β-lactamase encoding gene located on the IncX4 plasmid.Methods: Salmonella enterica was recovered from a diarrheal paediatric patient in Shenzhen, China. Antimicrobial susceptibility testing was performed by using the VITEK 2 system. Drug resistance genes were identified using targeted primers and Sanger sequencing. The transferability and genome location of mcr-1 was determined by performing conjugation, S1-PFGE and Southern blot hybridization analysis. WGS was performed by Illumina MiSeq sequencing and was assembled using the A5-Miseq pipeline, and gene annotation was performed using RAST 2.0. The database Centre for Genomic Epidemiology’s website was used to identify resistance genes and sequence types (STs).Results: We found that the isolate was extensively drug resistant and belonging to ST34, carrying an IncX4 plasmid with mcr-1, blaKPC-2 and blaCTX-M-15. We also noticed that genes blaPAO, fosA, catB, the mutation in oprD and mexT (MexEF-OprN efflux regulator), and exotoxin-encoding genes (exoS, exoY and exoT) were associated with resistance and virulence in the genome. In addition, heavy metal resistance genes as silP and silE were determined.Conclusion: This study highlights the potential risk of ST34 of Salmonella enterica serotype Typhimurium carrying multiple drug resistance encoding genes in a single IncX4 plasmid.Keywords: Salmonella enterica, MCR-1, KPC-1, CTX-M-15, paediatric patient

Aims and Objectives: The emergence and spread of extended-spectrum β-lactamases (ESBLs) particularly CTX-M producing multi-drug-resistant (MDR) Escherichia coli (E. coli) is one of the greatest challenges for community health globally. The study investigated the phenotypic and genotypic characteristics of ESBLs-producing E. coli recovered from pediatric patients from Shenzhen Children’s Hospital, China. Materials and methods: Present study, a total of 2,670 isolates of E. coli were collected from Shenzhen Children’s Hospital, China of which 950 were ESBLs producer. ESBLs production was confirmed by using the combination disc diffusion method, and antimicrobial susceptibility test was detected. In addition, β-lactamase-producing genes and co-existence of carbapenem/colistin resistance genes were determined by PCR assay and sequencing. The diversity and phylogenetic relationship were determined by multi-locus sequence typing method. Results: Thirty-five percent (n=950) prevalence of ESBLs-producing E. coli we reported in Shenzhen, China of which 50 ESBLs producing E. coli were randomly selected for a further characterization. All 50 ESBLs- producing E. coli isolates revealed MDR phenotype and 100% were resistant to Ampicillin/sulbactam, Ampicillin, Cefazolin, and Ceftriaxone. All 50 ESBLs producers harbored at least one type of β-lactamase gene particular blaCTX-M. The PCR and sequencing revealed the most common CTX-M subtype was blaCTX-M-15 (n=18), followed by blaCTX-M-14 (n=16), blaCTX-M-90 (n=9), blaCTX-M-55 (n=3), blaCTX-M-27, blaCTX-M-101, and blaCTX-M-211 each (n=1). Co-existence of blaCTX-M with blaTEM, blaSHV, blaGES, and blaVEB was detected in few isolates. Among identified sequence types, ST131 (12%) was more dominant in ESBLs-producing E. coli. Phylogenetic group A was the most prominent group among the ESBLs-producing E. coli based on multiplex PCR. Conclusion: Our study shows the prevalence of blaCTX-M gene in ESBLs-producing E. coli in pediatric patients in Shenzhen, China. We highlight the importance to monitor the emergence and trends of ESBLs-producing isolates in a pediatric healthcare setting.

Background Emergence and spread of β-lactamase resistant Klebsiella pneumoniae have posed a serious threat, especially in paediatric patients globally. The present study focuses on explore drug resistance profile and molecular characterization of carbapenemase and extended-spectrum β-lactamase producing K. pneumoniae isolated from paediatric patients in Shenzhen, China. Methods Present study, a total of 31 isolates of multi-drug resistant K. pneumoniae were collected from Shenzhen Children’s Hospital, China during Jan 2014 to December 2015. ESBLs production was confirmed by using the combination disc diffusion method followed by antimicrobial susceptibility. In addition, β-lactamase encoding genes were determined by PCR assay and sequencing. The genotypic diversity and phylogenetic relationship were determined by multi-locus sequence typing (MLST) method and pulsed-field gel electrophoresis (PFGE). Results We examined 31, unique K. pneumoniae isolates collected from 2014 and 2015 in Shenzhen Children’s Hospital, China. All the 31 isolates 100% were resistant to ceftazidime, ertapenem, ampicillin, cefazolin and ampicillin-sulbactam followed by ceftriaxone 94% (n = 29), aztreonam 89% (n = 26), cefepime 84% (n = 26), nitrofurantoin 75% (n = 24), piperacillin 52% (n = 16), and levofloxacin 49% (n = 15). Of the 31 β-lactamase gene coding isolates, blaCTX-M was mainly detected in about 100% (n = 31), followed by blaKPC 71% (n = 22), blaSHV 61% (n = 19), blaNDM 25% (n = 8), blaCYM 13% (n = 4), blaOXA-48 9% (n = 3), blaGES 9% (n = 3) and blaTEM 6% (n = 2). Seventeen distinct sequences type were observed with ST20 being mostly identified 16% (n = 5). Pulsed-field gel electrophoresis (PFGE) typing showed that identical profile for the isolates recovered from the Department of Intensive Care Unit and Department of Neurology of our hospital. Plasmid replicon typing result indicates the presence of IncFIS type as highest in all isolates as 61% (n = 19), followed by IncFIB 23% (n = 7), IncFIA and IncFIC 16% (n = 5) each. Conclusion Our study reports the occurrence and spread of extended β-lactamase K. pneumoniae ST20 and ST2407 for the first time, in Shenzhen, particularly in paediatric patients. To prevent and control the infection by limiting the spread of infection-causing organisms it is very crucial to detect the presence of resistant genes at an early stage.

Sandip Patil,1,2 Hongyu Chen,2 Xiaoli Zhang,2 Ma Lian,2 Pei-Gen Ren,1 Feiqiu Wen2 1Shenzhen Institute of Advanced Technology, Chinese Academy of Sciences, Shenzhen, Guangdong Province, People’s Republic of China; 2Shenzhen Children’s Hospital, Futian District, Shenzhen, Guangdong Province, People’s Republic of ChinaCorrespondence: Feiqiu WenShenzhen Children’s Hospital, 7019 Yitian Road, Futian District, Shenzhen, Guangdong Province 518038, People’s Republic of ChinaTel +86 18938690333Fax +86-755 83009888Email fwen62@163.comIntroduction: The emergence of multi-drug-resistant Gram-negative bacteria (GNB) is a concern in China and globally. This study investigated antimicrobial resistance traits and resistance determinant detection in GNB isolates from paediatric patients in China.Methods: In the present study, a total of 170 isolates of GNB including the most prevalent Escherichia coli, Klebsiella pneumoniae and Acinetobacter baumannii were collected from Shenzhen Children’s Hospital, China. ESBLs production was confirmed by using the combination disc diffusion method, and carbapenemase production was confirmed by using a carbapenem inactivation method followed by antimicrobial susceptibility. In addition, β-lactamase-encoding genes and co-existence of plasmid-borne colistin resistance mcr-1 gene were determined by PCR and sequencing.Results: Overall, 170 etiological agents (GNB) were recovered from 158 paediatric patients. The most prevalent species was E. coli 40% (n=68), followed by K. pneumoniae 17.64% (n=30), and Enterobacter cloacae 14.11% (n=24). Of 170 GNB, 71.76% (n=122) were multi-drug-resistant, 12.35% (n=21) extreme-drug resistant, and 7.64% (n=13) single-drug-resistant, while 8.23% (n=14) were sensitive to all of the studied antibiotics. The prevalence of ESBLs and carbapenemase producers were 60% and 17%, respectively. blaCTX-M was the most prevalent resistance gene (59.42%), followed by blaTEM (41.17%), blaSHV (34.270%), blaKPC (34.11%), blaOXA-48 (18.82%) and blaNDM-1 (17.64%).Conclusion: The present study provides insights into the linkage between the resistance patterns of GNB to commonly used antibiotics and their uses in China. The findings are useful for understandingthe genetics of resistance traits and difficulty in tackling of GNB in paediatric patients.Keywords: Gram-negative bacteria, antimicrobial susceptibility, ESBLs, carbapenemase, molecular characterization

Objectives mcr-1-mediated colistin resistance in Enterobacteriaceae is concerning, as colistin is used in treating multidrug-resistant Enterobacteriaceae infections. Rates of human mcr-1 gastrointestinal carriage have historically been low. We identified trends in human fecal mcr-1-positivity rates and colonization with mcr-1-positive+third-generation cephalosporin-resistant (3GC-R) Enterobacteriaceae in Guangzhou, China, and investigated the genetic contexts of mcr-1 in a subset of mcr-1-positive+3GC-R strains. Methods Fecal samples were collected from in-patients and out-patients submitting specimens to three hospitals (2011-2016). mcr-1 carriage trends were assessed using iterative sequential regression. A subset of mcr-1-positive isolates was sequenced (whole genome sequencing [WGS], Illumina), and genetic contexts (flanking regions, plasmids) of mcr-1 characterized. Results Of 8,022 fecal samples collected, 497 (6.2%) were mcr-1-positive, and 182 (2.3%) harbored mcr-1-positive+3GC-R Enterobacteriaceae. We observed marked increases in mcr-1 (0% [Apr/2011] to 31% [Mar/2016]) and more recent (since January 2014; 0% [Apr/2011] to 15% [Mar/2016]) increases in human colonization with mcr-1-positive+3GC-R Enterobacteriaceae (p WGS of mcr-1-positive+3GC-R isolates (70 Escherichia coli, 3 Klebsiella pneumoniae) demonstrated bacterial strain diversity (48 E. coli sequence types); mcr-1 in association with common plasmid backbones (IncI, IncHI2/HI2A, IncX4) and sometimes in multiple plasmids; frequent mcr-1 chromosomal integration; and high mobility of the mcr-1-associated insertion sequence ISApl1. Sequence similarity with published mcr-1 plasmid sequences was consistent with spread amongst animal/human reservoirs. Conclusions The high prevalence of mcr-1 in multidrug-resistant E. coli colonizing humans is a clinical threat; diverse genetic mechanisms (strains/plasmids/insertion sequences) have contributed to the dissemination of mcr-1, and will facilitate its persistence.

To the Editor: Plasmid-mediated, colistin-resistance mechanism gene mcr-1 was first identified in Escherichia coli isolates from food, food animals, and human patients in November 2015 (1). Reports on detection of mcr-1 in Enterobacteriaceae from humans and food animals soon followed from ≈12 countries (2–5). Here we report detection of mcr-1 in colistin-resistant E. coli isolated from companion animals and the possible transmission of mcr-1–harboring E. coli between companion animals and a person.

The first transferable plasmid-mediated colistin resistance gene, mcr-1 was reported in Escherichia coli isolates from food animals, food, and patients in China and now has been reported worldwide ([1][1]). Furthermore, cocarriage of mcr-1 and bla NDM has been reported in E. coli and other members

CTX-M-140, a novel CTX-M-type extended-spectrum β-lactamase (ESBL), was identified in cephalosporin-resistant clinical isolates of Proteus mirabilis . CTX-M-140 contained an alanine-to-threonine substitution at position 109 compared to its putative progenitor, CTX-M-14. When it was expressed in an Escherichia coli isogenic background, CTX-M-140 conferred 4- to 32-fold lower MICs of cephalosporins than those with CTX-M-14, indicating that the phenotype was attributable to this single substitution. For four mutants of CTX-M-14 that were constructed by site-directed mutagenesis (A109E, A109D, A109K, and A109R mutants), MICs of cephalosporins were similar to those for the E. coli host strain, which suggested that the alanine at position 109 was essential for cephalosporin hydrolysis. The kinetic properties of native CTX-M-14 and CTX-M-140 were consistent with the MICs for the E. coli clones. Compared with that of CTX-M-14, a lower hydrolytic activity against cephalosporins was observed for CTX-M-140. bla CTX-M-140 is located on the chromosome as determined by I-CeuI pulsed-field gel electrophoresis (I-CeuI-PFGE) and Southern hybridization. The genetic environment surrounding bla CTX-M-140 is identical to the sequence found in different plasmids with bla CTX-M-9-group genes among the Enterobacteriaceae . Genome sequencing and analysis showed that P. mirabilis strains with bla CTX-M-140 have a genome size of ∼4 Mbp, with a GC content of 38.7% and 23 putative antibiotic resistance genes. Our results indicate that alanine at position 109 is critical for the hydrolytic activity of CTX-M-14 against oxyimino-cephalosporins.

The gene mcr-1 was reported as the first plasmid-mediated colistin resistance gene in Escherichia coli isolates from food animals, food, and patients in China ([1][1]). Since then, detection of mcr-1 -positive strains has been reported in Enterobacteriaceae worldwide ([2][2][–][3][4][4]). The