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Background@#Extended-spectrum β-lactamase (ESBL)-producing Escherichia coli (E. coli) and Klebsiella pneumoniae (K. pneumoniae) are the important pathogens causing pneumonia. This study aimed to investigate the clinical characteristics and molecular epidemiology of ESBL-producing E. coli and K. pneumoniae causing pneumonia at a large teaching hospital in China.@*Methods@#We collected patient’s clinical data and ESBL-producing E. coli and K. pneumoniae strains causing pneumonia (from December 2015 to June 2016) at a hospital in Wuhan. The susceptibilities, multi-locus sequence typing, homologous analysis, ESBL genes by polymerase chain reaction and sequencing were determined.@*Results@#A total of 59 ESBL-producing strains (31 E. coli and 28 K. pneumoniae) isolated from patients with pneumonia were analyzed. The majority of strains were isolated from patients were with hospital-acquired pneumonia (37/59, 62.7%), followed by community-acquired pneumonia (13/59, 22.0%), and ventilator-related pneumonia (9/59, 15.3%). The E. coli ST131 (9 isolates, 29.0%) and K. pneumoniae ST11 (5 isolates, 17.9%) were the predominant sub-types. The most prevalent ESBL gene was CTX-M-14, followed by SHV-77, CTX-M-3, SHV-11, and CTX-M-27. At least 33 (55.9%) of the ESBL-producing strains carried two or more ESBL genes. The ISEcp1 and IS26 were found upstream of all blaCTX-M (CTX-Ms) and of most blaSHV (SHVs) (57.6%), respectively. Moreover, three ESBL-producing K. pneumoniae ST11 strains which were resistant to carbapenems carried the blaNDM-1 and blaKPC-2, two of which also bearing blaOXA-48 were resistant to all antibiotics (including Tigecycline).@*Conclusions@#Hospital-acquired pneumonia is more likely correlated with ESBL-producing E. coli and K. pneumoniae. ESBL-producing E. coli ST131 and multi-drug resistance ESBL-producing, as well as New Delhi metallo-β-lactamase-1 (NDM-1) and Klebsiella pneumoniae carbapenemases-2 (KPC-2) bearing K. pneumoniae ST11 are spreading in patients with pneumonia in hospital.
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Objective To investigate the drug resistant mechanism and homology of three strains of carbapenem-resistant Klebsiella pneumoniae (K.pneumoniae) isolated from different sites of one patient.Methods Three strains of carbapenem-resistant K.pneumoniae were isolated from femoral vein catheter tip,wound secretions and sputum of a patient with severe burns,respectively.Their carbapenemase,metallo-β-lactamase (MBL) and drug resistance genes were detected by modified Hodge test,double-disk synergy test and combination disk diffusion and PCR,respectively,and homology and biological typing were analyzed by enterobacterial repetitive intergenic consensus-PCR (ERIC-PCR) assay and multilocus sequence typing (MLST) technology,respectively.Results The carbapenemase and MBL of three strains of carbapenem-resistant K.pneumoniae were negative and positive,respectively.The blaNDM-1 gene was identified from the three strains,but other drug resistance genes such as blanC,blaGES,blaIMP,blaSPM,blaVIM,blaGIM and blaOXA-48 were not detected.ERIC-PCR showed that three isolates belonged to the same genotype,and MLST showed that they were type ST17.Conclusion Carring blaNDM-1 gene is the main cause leading to the drug resistance of three strains of carbapenem-resistant K.pneumoniae,and they belong to the same genotype.
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OBJECTIVE: To explore the bacteriostasis and plasmid elimination activities of different extracted parts of traditional Chinese medicine Radix Scutellariae Baicalensis on NDM-1 Acinetobacter calcoaceticus. METHODS: Thein vitro antibacterial effect of the extracts from Radix Scutellariae Baicalensis was studied. Inhibition zone and minimum inhibitory concentration(MIC) of the alcohol extract and water decoction were examined by using MH agar plates and microdilution susceptibility testing. The growth curve of the NDM-1 Acinetobacter calcoaceticus was tested after being incubated with alcohol extract and water decoction at sub-MIC. At three time points after incubation with different extracts at sub-MIC, photocopy dish method was used to screen plasmid-cured strains of NDM-1 Acinetobacter calcoaceticus. The plasmid-elimination rates and phenotypic changes were compared. RESULTS: Both the alcohol extract and water decoction of Radix Scutellariae Baicalensis inhibited the growth of NDM-1 Acinetobacter calcoaceticus. The MICs were 1.56 mg·mL-1 for the alcohol extract and 6.25 mg·mL-1 for the water decoction. The growth curve showed that the antibacterial effect of the alcohol extract was more obvious. Both the alcohol extract and water decoction of Radix Scutellariae Baicalensis had some degrees of plasmid elimination effect. The plasmid-elimination rates in the alcohol extract group were higher than those in the water decoction group. The plasmid-elimination rates were 61.27% for the alcohol extract and 49.78% for the water decoction, respectively. CONCLUSION: Radix Scutellariae Baicalensis can inhibit the growth of NDM-1Acinetobacter calcoaceticus and eliminate the drug-resistant plasmid effectively and has the potential to be used to control the spread of pan-drug resistant Acinetobacter strains or be an adjuvant treatment method for clinical infections. Its alcohol extract has better effect.
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Introduction: Infections due to multidrug‑resistant (MDR) pathogens are a medical challenge. There is considerable apprehension among clinicians regarding pathogens reported as carrying New Delhi metallo‑β‑lactamase‑1 (NDM) and Klebsiella pneumoniae carbapenemase (KPC) genes from their patients. In the face of extremely high rates of antimicrobial resistance, it is essential to gauge the clinical significance of isolation of pathogens carrying these genes from clinical samples. This study compares the outcome of patients infected with pathogens carrying NDM/KPC genes versus those without these genes. Methods: The study was conducted over a 1‑year period at a Level‑1 trauma centre. Hospital‑acquired infections were diagnosed on the basis of CDC’s criteria. The correlation of isolation of a multi‑resistant pathogen carrying KPC or NDM genes with the clinical outcome was ascertained. Results: A total of 276 consecutive patients admitted to the Intensive Care Units/wards of the JPNA Trauma Centre were included in this study. Of the 371 isolates recovered from these patients, 116 were from patients who had a fatal outcome. The difference in prevalence of blaNDM and blaKPC was not significant in any genera of Gram‑negative pathogens isolated from patients who survived versus those who had a fatal outcome. Conclusion: Isolation of MDR pathogens carrying NDM/KPC genes from clinical samples is not always a harbinger of a fatal outcome. Efforts should be made to prevent cross‑transmission of these pathogens.
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Background: The ability of microorganisms to evade antibiotic pressure is challenging in healthcare as patients have little or no drug treatment options. Detection of the prevalence of antibacterial resistance pattern helps towards improved antibiotic policy and empirical treatment. Objectives: We carried out antibiogram profiling and documented the prevalence and co-prevalence of New Delhi metallo-β-lactamase (NDM) and extended spectrum β-lactamases (ESBL) encoding genes in urinary Escherichia coli and Klebsiella pneumonia isolates. Materials and Methods: Antibiotic susceptibilities were tested for 241 isolates of E. coli and K. pneumoniae from urine samples collected from out- and hospitalised patients. Polymerase chain reaction (PCR) was carried out on isolates tested positive for phenotypic production of metallo-β-lactamase and ESBL. A multiplex PCR assay was designed to detect the genes. Results: Multiplex PCR assay designed had a limit of detection of 103 CFU/mL in vitro. NDM detected was significantly higher among K. pneumoniae compared to E. coli (69.2% vs. 18.2%; P = 0.001). Of 17, 14 NDM positive isolates also harboured ESBL genes. The co-production of CTX-M + TEM + NDM (3/9; 33.3% and 5/8; 62.5%) was most common in K. pneumoniae and E. coli, respectively while CTX-M + TEM + SHV + NDM was found in one isolate. Of the 156 phenotypically ESBL producing isolates, CTX-M, TEM and SHV was detected by PCR in 85, 53 and 24 isolates, respectively. Conclusion: NDM and ESBL co-producing isolates were both community (64.7%) and hospital (35.29%) acquired among E. coli. Antibiotic resistance can be effectively evaluated by a cost and time effective molecular method, such as the multiplex PCR used in this study, which complement culture and sensitivity tests.
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Objective To determine new delhi metallo-β-lactamase-1 (NDM-1 )gene in strains of gram-negative bacilli with de-creased sensitivity to carbapenems,and to investigate the epidemic situation of strains carrying NDM-1 gene in Guangzhou area. Methods 105 strains of gram-negative bacilli with decreased sensitivity to carbapenems isolated from 201 1 to 2014 were collected. The conserved sequences of NDM-1 gene were screened initially by using polymerase chain reaction(PCR)amplification,and posi-tive strains were confirmed by PCR amplification of the whole sequence.Then NDM-1 gene was cloned into plasmid pUCm-T and sequenced.Results The resistance rates of Enterobacteriaceae bacteria against meropenem,ertapenem and imipenem were 29.09%, 50.91% and 29.09%,respectively.All strains of Acinetobacter baumanii were resistant to meropenem and imipenem.The resist-ance rates of Pseudomonas aeruginosa against meropenem and imipenem both were 88.46%.4 strains were NDM-1 gene positive, including 1 strain of Klebsiella pneumoniae,2 strains of Escherichia coli,1 strain of Enterobacter cloacae.Successful establishment of cloning plasmid pUCm-T-NDM-1 was confirmed by using double enzyme digestion and sequencing.The sequencing results were compared with BLAST,it was showed that the sequences were exactly the same in four cloned plasmids,and sequences of NDM-1 were also exactly the same with those in domestic and foreign.Conclusion Strains of NDM-1 producing gram-negative bacilli exist in Guangzhou area,and whole sequence of NDM-1 gene carried in these strains are exactly the same with those found in foreign.
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Background & objectives: Carbapenemase-producing Enterobacteriaceae isolates have been increasingly identified worldwide. Though molecular data regarding New Delhi metallo-beta-lactamase-1 (NDM-1) producers are available, data regarding their rate of infection in a hospital setting and percentage among different clinical isolates are scarce. Hence, this study was undertaken to determine the occurrence of blaNDM-1 gene among clinical isolates of multidrug resistant Gram-negative bacilli (MDRGNB) in a tertiary care centre in Bangalore, Karnataka, India. Methods: A total of 74 MDRGNB isolates were studied. These were screened for MBL production by phenotypic assays such as double disk synergy test (DDST) and Modified Hodge’s test (MHT). PCR was performed for the molecular detection of the gene and antibiograms were confirmed by automated bacteriology system. Results: Of the 74 MDRGNB isolates, 34 were positive for blaNDM-1 gene. All isolates were resistant to aztreonam and two isolates were resistant to tigecycline. Complete resistance to the tested carbapenems was seen in 28 (82.35%) of the positive isolates whereas variable carbapenem resistance was seen in six (17.64%) of the positive clinical isolates. Of the total 34 PCR positive isolates, 33 (97.05%) NDM-1 producers were identified by DDST and 26 (76.47%) by MHT as producers of MBL. Interpretation & conclusions: A high percentage of plasmid encoded NDM was noted in MDRGNB. Phenotypic and molecular screening should be employed along with routine antimicrobial susceptibility testing to reflect the true number of metallo-beta-lactamase producers.
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Objeetive To explore the mechanism of drug resistance of New Delhi metallo-β-lactamase-1 (NDM-1) producing Enterobacteriaceae,and to investigate the characteristics of blaNDM-1 carrying plasmid and its gene environment.Methods A total of 48 strains of carbapenem-resistant Enterobacteriaceae were successively collected from six general hospitals in south China during August 2011 and January 2013.Escherichia coli J53 was used for plasmid conjugation.Modified Hodge test was performed,and PCR method was used for the detection of carbarpenase-related genes.The relative molecular mass of the blaNDM-1 carrying plasmid was determined using pulsed field gel electrophoresis (PFGE)assay,and enzyme digestion was performed to investigate the homology and incompatibility group of the plasmid.Clinical feature of blaNDM-1 producing Enterobacteriaceae infection was also investigated.Results Among 48 strains of carbapenem-resistant Enterobacteriaceae,43 were positive in modified Hodge tests.blaVIM,blaGIM and blaSPM genes were negative in all strains,while blaNDM-1 was positive in 19 strains including 3 strains of Escherichia coli,5 strains of Klebsiella pneumoniae,6 strains of Enterobacter cloacae,3 strains of Citrobacterfreundii,1 strain of Klebsiella oxytoca and 1 strain of Providencia rettgeri.All the 19 strains were resistant to imipenem,cefotaxime,ceftazidime,cefepime,aztreonam and piperacillin/tazobactam,47.3％ strains were resistant to ciprofloxacin and levofloxacin,but 68.4％ strains were sensitive to amikacin.Conjugation experiment showed that,blaNDM-1 carrying plasmids in 13 strains were transmitted to the Escherichia coli J53.The conjugants were resistant to imipenem,ceftazidime,cefotaxime and piperacillin/tazobactam,but were sensitive to amikacin,ciprofloxacin and levofloxacin.All genes in conjugant J-FR90 (Providencia rettgeri) were negative,while the remaining 12 conjugants carried blaNDM-1,blaSHV and aac-(6')-Ib genes.PFGE showed that,the sizes of all blaNDM-1 carrying plasmids were about 50 kb,and more than 80％ of their macrorestriction maps were similar.The plasmid belonged to incompatibility group IncX3,and exhibited 100％ passage stability after 500 generations of propagation.Among 19 patients infected with NDM-1 producing Enterobacteriaceae,6 died and 13 survived.Conclusions NDM-1 producing Enterobacteriaceae is emerging in south China,and blaNDM-1 is transmitted to Enterobacteriaceae through IncX3.Patients infected with NDM-1 producing Enterobacteriaceae usually have good prognosis.
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Carbapenem resistance among clinical isolates of Enterobacteriaceae, especially Escherichia coli and Klebsiella pneumoniae, is largely conferred by metallo-β-lactamase (MBL). Fifty-one non repetitive isolates of carbapenem-resistant (Meropenem and Imipenem) E. coli and K. pneumoniae were studied to determine the molecular mechanism for resistance. Presence of blaNDM and blaVIM was determined by polymerase chain reaction (PCR) and DNA sequencing. blaNDM was detected from majority of carbapenem-resistant K. pneumoniae (75%) and E. coli (66.6%). Timely detection and appropriate and aggressive infection control measures are required to control the spread of these bacteria in healthcare settings.