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Multidrug-resistant bacteria that can′t be treated with any common antibacterial drugs have become a global medical crisis. Therefore, there is an urgent need for new antibacterial potentiators to restore the sensitivity of bacteria to the antibacterial drug. This review elaborates on the novel antibacterial synergistic methods and their underlying mechanisms, clinical experimental data and efficacy, and the progress of drug research and development. This review aims to raise awareness about antibacterial potentiators among the public.
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Objective:To explore the serotype, antibiotic resistance and β-lactamase gene of Haemophilus influenzae strains isolated from hospitalized children, thus providing reference for clinical diagnosis and treatment. Methods:A total of 148 Haemophilus influenzae strains collected from January 2016 to December 2018 in hospitalized children of Children′s Hospital, Capital Institute of Pediatrics were retrospectively analyzed.The serotype and genotype of Haemophilus influenzae strains were examined by slide agglutination test and PCR, respectively.The sensitivity of isolates to Ampicillin and other antimicrobials was detected by the E-test and disk diffusion methods.The β-lactamase phenotype was tested by nitrocefin disk method.The carrying of β-lactamase gene TEM-1 and ROB-1 were detected by PCR.The drug resistance rate was compared by χ2 test. Results:All the 148 strains were nontypeable Haemophilus influenzae (NTHi), and capsular gene was not amplified.The rate of resistance to Ampicillin, Ampicillin/Sulbactam, Cefuroxime, and Azithromycin were 68.9%(102/148 strains), 40.5%(60/148 strains), 53.4%(79/148 strains) and 56.1%(83/148 strains), respectively.The Haemophilus influenzae isolates showed the highest resistance rate to Trimethoprim-sulfamethoxazole, which was up to 91.9%(136/148 strains). The sensitive rate of isolates to Ceftriaxone, Meropenem and Levofloxacin were all 100.0%(148/148 strains). The prevalence of β-lactamase was 64.8%(96/148 strains) in Haemophilus influenzae and the genotype was TEM-1.The drug resistance rates of β-lactamase positive strains to Ampicillin, Ampicillin/Sulbactam and Azithromycin were significantly higher than those of other strains( χ2=123.222, 27.973, 70.273, all P<0.01). Conclusions:The most prevalent serotype of Haemophilus influenzae is NTHi in children. Haemophilus influenzae carried TEM-1 gene had a high positive rate of β-lactamase production, which was the main mechanism of drug resistance to Ampicillin.Ceftriaxone and Meropenem were the most active agents against Haemophilus influenzae.
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OBJECTIVE To investigate the treatment plan for az treonam-resistant metallo- β-lactamase（MBL）-producing Enterobacteriaceae infection in pediatric solid organ transplant recipients. METHODS The clinical data of aztreonam-resistant MBL-producing Klebsiella pneumoniae caused intra-abdominal infection of an infant after liver transplantation were retrospectively analyzed. Abdominal infection occurred after operation. The pathogenic bacterium was MBL-producing K. pneumoniae . The drug sensitivity results showed that the infant was resistant to aztreonam. Based on the results of sensitivity test ，polymyxin B combined with tigecycline were selected as initial regimen. The treatment effect was poor ，with recurrent disease and shock spots. The clinical pharmacist assisted the clinician to formulate treatment regimen of ceftazidime avibactam 0.5 g，q8 h combined with aztreonam 0.18 g，q6 h. Relevant domestic and foreign literature were reviewed ，and the treatment plan of MBL-producing Enterobacteriaceae infection after solid organ transplantation was summarized. RESULTS & CONCLUSIONS The infant was finally cured and discharged with ceftazidime avibatan combined and aztreonam. Several foreign literature reported that ceftazidime avibactam combined with aztreonam could effectively treat the infection caused by aztreonam-resistant MBL-producing Enterobacteriaceae infection in patients with organ transplantation. It is expected to be an effective treatment for aztreonam-resistant MBL-producing Enterobacteriaceae infection in pediatric solid organ transplant recipients.
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This article reviews the status quo of new antimicrobial agents that have been approved or undergoing phase Ⅱ/Ⅲ clinical trials in last five years at home and abroad, including new β-lactamase inhibitors and their compound preparations, oxazolidinones, tetracyclines, aminoglycosides, glycopeptides, quinolones, new antifungal agents, cyclic lipopeptides and new anti-mycobacterial agents. The antibacterial activities, main mechanisms of drug resistance, and progress of clinical studies of 27 new drugs were introduced to provide a reference for their clinical application.
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Objective:To investigate the antimicrobial resistance characteristics of carbapenem-resistant Enterobacteriaceae （CRE） isolated from outpatients with diarrhea in Shanghai， and provide support for surveillance， prevention and control of CRE. Methods:A total of 800 fecal swabs of the outpatients with diarrhea were collected from 23 sentinel hospitals for diarrhea pathogen surveillance in Shanghai from January 2018 to December 2019. The drug-resistant strains were isolated using MacConkey plates containing 1 μg/μL meropenem. The collected strains were identified preliminarily by the VITEK-2 Compact system and VITEK mass spectrometry. The minimum inhibitory concentration （MIC） of the strain was determined by the broth microdilution method. The multi-locus sequence typing （MLST） method and pulsed-field gel electrophoresis （PFGE） were used to analyze the homology of drug-resistant strains. The transferability of the resistance gene was investigated by a junction experiment. High-throughput sequencing was used to characterize the isolates. Results:Seven non-repetitive CRE isolates were multi-drug resistant carbapenem-resistant Escherichia coli （CREC） strains that produce New Delhi metallo-β-lactamase （NDM） with resistance to several commonly used antibiotics in clinical therapy. The molecular typing results showed that the CRE strains had different sequence types， and diverse PFGE patterns. The stains were all positive for blaNDM genes， including blaNDM-5 and blaNDM-13， with blaNDM-5 as the main type. The carbapenem-resistant genes could be transferred to EC600 by conjugation. Conclusion:The intestinal carbapenem-resistant strains in this study are all NDM-producing Escherichia coli. The isolates carried blaNDM and other resistance genes. The MLST analysis showed that they belonged to different cloning types. Antimicrobial resistance genes could be horizontally transferred to EC600 by conjugation.
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Active surveillance culture (ASC) can help detect hidden reservoirs, but the routine use of ASC for extended spectrum β-lactamase-producing Enterobacteriaceae is controversial in an endemic situation. We aimed to determine the prevalence and risk factors of extended spectrum β-lactamase-producing Klebsiella pneumoniae (EBSL-Kpn) colonization among intensive care unit (ICU)-admitted patients. Prospective screening of ESBL-Kpn colonization was performed for ICU-admitted patients within 48 hours for two months. A perirectal swab sample was inoculated on MacConkey agar supplemented with 2 µg/mL ceftazidime. ESBL genotype was determined by PCR-sequencing, and clonal relatedness was evaluated by pulsed-field gel electrophoresis (PFGE). The risk factors of ESBL-Kpn colonization were evaluated. The ESBL-Kpn colonization rate among the 281 patients at ICU admission was 6.4% (18/281), and bla(CTX-M-15) was detected in all isolates. ESBL producers also showed resistance to fluoroquinolone (38.9%, 7/18). All isolates had the same ESBL genotype (bla(CTX-M-15)) and a highly clustered PFGE pattern, suggesting cross-transmission without a documented outbreak. In univariate analysis, the risk factor for ESBL-Kpn colonization over the control was the length of hospital stay (odds ratio=1.062; P=0.019). Routine use of ASC could help control endemic ESBL–Kpn for ICU patients.
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Humans , Agar , Ceftazidime , Colon , Critical Care , Electrophoresis, Gel, Pulsed-Field , Enterobacteriaceae , Genotype , Intensive Care Units , Klebsiella pneumoniae , Klebsiella , Length of Stay , Mass Screening , Prevalence , Prospective Studies , Risk FactorsABSTRACT
Objective To investigate the drug resistance characteristics and epidemic trend of Escherichia coli in Anning, Yunnan, and to provide a reference for clinical rational use of antibiotics. Methods A total of 376 strains of Escherichia coli were isolated from June 2018 to June 2019 from Kungang Hospital of Yunnan Province. The ESBLs producing strains were screened by double disk method and the sensitivity of ESBLs to antibiotics was detected by K-B method. The genotyping of ESBLs strains and the class I, II and III integrase genes in integron 3' and 5' conservative regions was conducted using polymerase chain reaction (PCR). Results The detection rate of ESBLs producing Escherichia coli was 53.19% (200/376). ESBLs-producing Escherichia coli had a low resistance rate to carbapenem antibacterial drugs with a relatively high sensitivity. The resistance rates to amikacin and piperacillin were 7.50% and 12.50% respectively, which had good antibacterial activity. The resistance rate to other antibiotics was high. There were 74.00% (148/ 200) of ESBLs-producing Escherichia coli carrying CTX-M gene, 34.50% (69/200) carrying TEM genes, and 1.00% (2/200) of strains carrying SHV genes. In addition, there were 9.00% (18/200) of strains carrying both CTX-M and TEM genes, and 0.50% (1/200) of strains carrying both CTX-M and SHV genes. The detection rate of integrons accounted for 37.00% (74/200), all of which were class I integrons. Conclusion The prevalence of ESBLs-producing Escherichia coli was relatively high in Anning, Yunnan. ESBLs-producing Escherichia coli showed a trend of multi-drug resistance. The genotype was mainly CTX-M, and the integron was classified as class I.
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In 2017, the World Health Organization published its first-ever list of antimicrobial-resistant bacteria “prioritypathogens,” a catalog of 12 families of bacteria posing the greatest threat to human health. This list focuses onthe risk of Gram-negative bacteria for multiple drug-resistant. Pseudomonas aeruginosa was at the top of the listand critical. A current study aiming to demonstrate the prevalence of β-lactamase among multidrug-resistant P.aeruginosa strains isolated from burn wound patients phenotypically. The isolates were identified then antibioticsusceptibility tested against 10 antipseudomonal agents, finally, phenotypically β-lactamase (ESβLs, MβLs, andAmp-C) production screened by combined disk diffusion test and Imipenem-ethylenediaminetetraacetic acid.Results in the current study identified 98 P. aeruginosa isolates from 200 clinical specimens obtained from burnwound patients. Our result showed 65 (66.3%) of the 98 P. aeruginosa isolates were multiple drug-resistant(MDR) strains. Out of 65 isolates, 37 (56.9%), 21 (32.3%), and 40 (61.5%) were ESβLs, MβLs, and Amp-Cproducing P. aeruginosa, respectively, according to phenotypic detection method. We found co-expression ofvarious β-lactamases. In the present study, 16 isolates showed co-existence of AmpC + ESBL, 16 isolates werehaving ESBL + MBL + AmpC, and five isolates were having co-existence of ESBL + MBL. The occurrence ofESβLs, MβLs, and Amp-C producing P. aeruginosa was demonstrated, calling for phenotypical determinationof antibiotic resistance mechanisms should be performed regularly to guide antibiotic selection during therapy.Significant conclusions drawn from this work include a rise in the rate of β-lactamase (ESβLs, MβLs, andAmp-C) in MDR P. aeruginosa. Later research should, therefore, focus on the study of molecular characterization.
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Background: The multidrug resistant among uropathogenic E. coli has become a potential threat to global health. The aim of the current study to evaluate the antimicrobial activities of nitrofurantoin and fosfomycin along with other antimicrobials against Extended Spectrum β-Lactamases (ESBL) and AmpC producer isolates from the most common organism E. coli. Methods: A total of 6046 clean catch midstream urine samples were collected and processed in Microbiology department of tertiary care hospital. The antimicrobial susceptibility of E. coli isolates was initially screened by Kirby-Bauer disk diffusion method. The resistant isolates were confirmed to be ESBL and AmpC producers by their respective phenotypic confirmatory tests of combined disc method. Results: Out of 6046 patients there were 1855 E. coli positive patients. Maximum patients in the age group of 21-30 years were 51.5% followed by 31-40 years where patients were 26%. 64.4% E. coli were isolated from female patients and 35.6% from male patients. E. coli showed higher sensitivity towards, fosfomycin (100%), imipenem (100%), nitrofurantoin (84.1%), piperacillin and tazobactam (77.3%), amikacin (76.1%) and while they showed high degree resistance pattern against Penicillin, cotrimoxazole, ciprofloxacin, norfloxacin and 2nd and 3rd generation cephalosporin. Out of 1855 E. coli, multi drug resistance was seen in 520 E. coli isolates. ESBL production was observed among 50% of E. coli isolates by combined disk method. Out of 520 isolates, 150 isolates showed resistance to one or more extended-spectrum cephalosporins and cefoxitin by Kirby-Bauer disk diffusion method. These were selected and screened for ESBL and AmpC production. Among 150 cefoxitin-resistant isolates, AmpC phenotype was detected in 100 isolates (66.6%) by AmpC disc method. The overall occurrence of AmpC in the study was found to be 19.2%. Susceptibility of ESBL and AmpC producers to fosfomycin, imipenem, nitrofurantoin and amikacin were found to be 100%, 98.5%, 89% and 75% respectively. Conclusions: There is increased prevalence of ESBL and AmpC producing E. coli. Thus, early detection of ESBL and AmpC producer E. coli by simple phenotypic methods is necessary to avoid treatment failure, where molecular techniques are not available.
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Background: The multidrug resistant among uropathogenic E. coli has become a potential threat to global health. The aim of the current study to evaluate the antimicrobial activities of nitrofurantoin and fosfomycin along with other antimicrobials against Extended Spectrum β-Lactamases (ESBL) and AmpC producer isolates from the most common organism E. coli. Methods: A total of 6046 clean catch midstream urine samples were collected and processed in Microbiology department of tertiary care hospital. The antimicrobial susceptibility of E. coli isolates was initially screened by Kirby-Bauer disk diffusion method. The resistant isolates were confirmed to be ESBL and AmpC producers by their respective phenotypic confirmatory tests of combined disc method. Results: Out of 6046 patients there were 1855 E. coli positive patients. Maximum patients in the age group of 21-30 years were 51.5% followed by 31-40 years where patients were 26%. 64.4% E. coli were isolated from female patients and 35.6% from male patients. E. coli showed higher sensitivity towards, fosfomycin (100%), imipenem (100%), nitrofurantoin (84.1%), piperacillin and tazobactam (77.3%), amikacin (76.1%) and while they showed high degree resistance pattern against Penicillin, cotrimoxazole, ciprofloxacin, norfloxacin and 2nd and 3rd generation cephalosporin. Out of 1855 E. coli, multi drug resistance was seen in 520 E. coli isolates. ESBL production was observed among 50% of E. coli isolates by combined disk method. Out of 520 isolates, 150 isolates showed resistance to one or more extended-spectrum cephalosporins and cefoxitin by Kirby-Bauer disk diffusion method. These were selected and screened for ESBL and AmpC production. Among 150 cefoxitin-resistant isolates, AmpC phenotype was detected in 100 isolates (66.6%) by AmpC disc method. The overall occurrence of AmpC in the study was found to be 19.2%. Susceptibility of ESBL and AmpC producers to fosfomycin, imipenem, nitrofurantoin and amikacin were found to be 100%, 98.5%, 89% and 75% respectively. Conclusions: There is increased prevalence of ESBL and AmpC producing E. coli. Thus, early detection of ESBL and AmpC producer E. coli by simple phenotypic methods is necessary to avoid treatment failure, where molecular techniques are not available.
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Background: Every time an antibiotic is used, whether appropriately or not, the probability of the development and spread of antibiotic resistant bacteria is increased. Thus, multidrug resistant bacteria particularly ESBL (Extended spectrum βlactamase), Amp C and carbapenemases producing gram negative bacilli have emerged as a major health problem all over the world. Considering new treatment options as a carbapenems sparing and resistance prevention modality, this study was aimed to know the in vitro susceptibility pattern of Cefepime/Tazobactam (CPM/TZ) in comparison to other β-Lactam/ β-Lactamase inhibitors (BL/BLI) and carbapenems against GNB.Methods: A prospective study was conducted on all clinical samples received for a period of about 1 year. Identification and susceptibility of all isolates was done by Vitek 2 Compact system. Susceptibility of CPM/ TZ was done by disc diffusion method on the basis of CLSI guidelines. Both fermenters (E. coli and Klebsiella pneumoniae) and non-fermenters (Acintobacter baumanii and Pseudomonas aeruginosa) were included in the study.Results: Out of 550 GNB isolates the most common was E. coli (61.8%), Acintobacter baumanii (16%), Klebsiella pneumoniae (14.9%) and Pseudomonas aeruginosa (7.3%). Cefepime/tazobactam had a much higher susceptibility of 68% compared to cefepime (28%). Among the BL/BLI combinations tested cefepime/tazobactam (68%) showed the maximum percentage of susceptibility followed by cefoperazone/sulbactam (61.5%) and piperacillin/tazobactam (57.6%). Amongst all GNB isolates cefepime/tazobactam (68%) sensitivity was very much comparable to imipenem (71.8%) and meropenem (69.6%).Conclusions: CPM/TZ exhibited the best in vitro activity in comparison to the other BL/BLI. This new combination of cefepime/tazobactam appears to be a promising alternative therapeutic option to carbapenems. Clinical studies are needed to confirm this in vitro study result.
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BACKGROUND: Escherichia coli and Klebsiella pneumoniae clinical isolates producing CTX-M extendedspectrum β-lactamases (ESBLs) were assessed for antimicrobial resistance phenotypes varied by group of enzymes. METHODS: A total of 1,338 blood isolates, including 959 E. coli and 379 K. pneumoniae, were studied. All the strains were collected between January and July 2017 from eight general hospitals in South Korea. The species were identified by matrix-assisted laser desorption ionization-time of flight mass spectrometry. Antimicrobial susceptibilities were determined by disk diffusion methods and ESBL phenotypes by double-disk synergy tests using disks containing cefotaxime, ceftazidime, cefepime, aztreonam, and clavulanic acid (CA). The genes for β-lactamases were identified by PCR and sequencing. RESULTS: Of total microbes, 31.6% (303/959) E. coli and 24.0% (91/379) K. pneumoniae were resistant to cefotaxime and 28.1% (269/959) E. coli and 20.1% (76/379) K. pneumoniae were CTX-M-type ESBL producers. Among the detected CTX-M ESBLs, 58.0% (156/269) in E. coli and 86.8% (66/76) in K. pneumoniae belonged to group 1, 46.8% (126/269) in E. coli and 14.5% (11/76) in K. pneumoniae were group 9. Ten E. coli and one K. pneumoniae isolates co-produced both groups of CTX-M ESBL. The group 1 CTX-M producers had a higher level of resistance to cefotaxime, ceftazidime, cefepime, and aztreonam and exhibited stronger synergistic activities when combined with CA compared to group 9. CONCLUSION: ESBL phenotypes differ by CTX-M ESBL group and phenotype testing with drugs including 4th generation cephalosporins and monobactams is critical for screening CTX-M-producers with better sensitivity.
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Aztreonam , Cefotaxime , Ceftazidime , Cephalosporins , Clavulanic Acid , Diffusion , Escherichia coli , Hospitals, General , Klebsiella pneumoniae , Korea , Mass Screening , Mass Spectrometry , Monobactams , Phenotype , Pneumonia , Polymerase Chain ReactionABSTRACT
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 genetic characteristics of drug resistance and homology of extended-spectrum β-lactamase (ESBLs)-producing Klebsiella pneumoniae (Kpn) in hospitalized children in the pediatric intensive care unit (PICU) in Guiyang area.@*Methods@#The Kpn strains were collected from hospitalized children at 3 PICU from the Affiliated Hospital of Guizhou Medical University, Guizhou Provincial People′s Hospital and Guiyang Children′s Hospital from September 2014 to December 2016.Automatic bacteria identification instrument and Kirby-Bauer method were used to identify Kpn strains and confirm ESBLs phenotype respectively.The drug resistance genes were detected by using polymerase chain reaction (PCR), and their homology was analyzed by means of pulsed field gel electrophoresis (PFGE) and cluster analysis.@*Results@#(1) A total of 207 non-repetitive Kpn strains were isolated, of which 128 strains produced ESBLs (61.8%). There was no significant difference in the ESBLs detection rates among the different hospitals, years and types of samples(χ2=0.40, 5.19, 4.68, all P>0.05). (2) Among those 128 ESBLs-producing Kpn strains, 123 strains (96.1%) were found to have drug-resistant genes, of which the detection rate of SHV type was the highest, accounting for 87.5%.These 3 drug resistance genotypes were distributed in 7 modes, of which 85.2% were carrying more than 2 genotypes.(3) PFGE genotypic assay showed that there were 109 genotypes and 5 dominant clones.The PICU at 3 hospitals were all prevalent with type A strain, accounting for 14.8%.In 2015, there was a short-term outbreak of type A strain in Guiyang Children′s Hospital.While, the resistance phenotypes of Kpn and the genotype of PFGE could both be consistent or different.@*Conclusions@#The ESBLs-producing Kpn at PICU in Guiyang area has the characteristics of multi-drug resistance, its drug-resistant genotypes have diversified, and there is a small-scale short-term outbreak epidemic, which poses a serious threat to clinical anti-infection treatment.It is necessary to strengthen clinical drug resistance monitoring and adopt effective infection control measures to prevent and control the spread of nosocomial infections.
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Objective To evaluate the in vitro activity of ceftazidime-avibactam (CAZ-AVI) alone or in combination with colistin (COL) against clinically isolated extensively drug-resistant Pseudomonas aeruginosa (XDR-PA). Methods Minimum inhibitory concentration (MIC) of 16 clinical XDR-PA isolates was determined by broth dilution method and chessboard design when CAZ-AVI and COL were used alone or in combination, then the combined inhibitory concentration index (FICI) was calculated. Class A [Klebsiella pneumoniae carbapenemase β-lactamase (blaKPC), Guiana extended-spectrum β-lactamase (blaGES)], Class B [imipenemase β-lactamase (blaIMP), Verona-Integronmetallo β-lactamase (blaVIM), New Delhi metallo β-lactamase (blaNDM), German imipenemase β-lactamase (blaGIM), Sao Paulo metallo -β- lactamase (blaSPM)], Class C [AmpC β-lactamase (blaAmpC)], Class D [oxacillinase β-lactamase (blaOXA)] β- lactamase-related resistance genes were detected by polymerase chain reaction. Drug-resistant mutation frequencies of each strain were determined on a drug-containing plate. The time kill curves of three XDR-PA were plotted by colony counting method. A biofilm model was established in vitro, and the synergistic effect of CAZ-AVI and COL on biofilm inhibition was detected by methythiazolyl tetrazolium assay (MTT). Results The MICs of 16 XDR-PA for CAZ-AVI ranged from 1 mg/L to 128 mg/L, and three of the isolates showed resistance (MIC > 8 mg/L). The FICI range of CAZ-AVI combined with COL was 0.312-1.000. Four isolates were synergistic, while the other 12 isolates were additive. Three isolates resistant to CAZ-AVI contained Class B resistance genes such as blaIMP and blaVIM, while 13 susceptible isolates carried resistance genes belonging to Class A, C or D. The logarithm values of mutation frequencies of drug resistance in CAZ-AVI group, COL group and combination group were -4.81±0.88, -7.06±0.69 and -9.70 (-9.78, -9.53), respectively. There were significant differences among the three groups (H = 33.601, P < 0.001), and between every two groups (adjusted P < 0.05). In time kill curves, the phytoplankton load of three XDR-PA decreased more than 6 log CFU/L when these two drugs were used together, and number of PA1819 planktonic bacteria decreased more than 5.1 log CFU/L compared with monotherapy group. Viable quantity in biofilm (A490) of normal saline group, CAZ-AVI group, COL group and CAZ-AVI-COL group were 0.665±0.068, 0.540±0.072, 0.494±0.642 and 0.317±0.080, respectively. There was significant difference between the other two groups (all P < 0.001), except for that between CAZ-AVI group and COL group (P = 0.109). Conclusions CAZ-AVI combined with COL can effectively improve the bactericidal effect of each drug alone on XDR-PA. The regimen can also reduce the production of drug-resistant bacteria and inhibit the formation of biofilm. Therefore, it is a potential treatment for XDR-PA infection.
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Objective To evaluate the in vitro activity of ceftazidime-avibactam (CAZ-AVI) alone or in combination with colistin (COL) against clinically isolated extensively drug-resistant Pseudomonas aeruginosa (XDR-PA). Methods Minimum inhibitory concentration (MIC) of 16 clinical XDR-PA isolates was determined by broth dilution method and chessboard design when CAZ-AVI and COL were used alone or in combination, then the combined inhibitory concentration index (FICI) was calculated. Class A [Klebsiella pneumoniae carbapenemase β-lactamase (blaKPC), Guiana extended-spectrum β-lactamase (blaGES)], Class B [imipenemase β-lactamase (blaIMP), Verona-Integronmetallo β-lactamase (blaVIM), New Delhi metallo β-lactamase (blaNDM), German imipenemase β-lactamase (blaGIM), Sao Paulo metallo -β- lactamase (blaSPM)], Class C [AmpC β-lactamase (blaAmpC)], Class D [oxacillinase β-lactamase (blaOXA)] β- lactamase-related resistance genes were detected by polymerase chain reaction. Drug-resistant mutation frequencies of each strain were determined on a drug-containing plate. The time kill curves of three XDR-PA were plotted by colony counting method. A biofilm model was established in vitro, and the synergistic effect of CAZ-AVI and COL on biofilm inhibition was detected by methythiazolyl tetrazolium assay (MTT). Results The MICs of 16 XDR-PA for CAZ-AVI ranged from 1 mg/L to 128 mg/L, and three of the isolates showed resistance (MIC > 8 mg/L). The FICI range of CAZ-AVI combined with COL was 0.312-1.000. Four isolates were synergistic, while the other 12 isolates were additive. Three isolates resistant to CAZ-AVI contained Class B resistance genes such as blaIMP and blaVIM, while 13 susceptible isolates carried resistance genes belonging to Class A, C or D. The logarithm values of mutation frequencies of drug resistance in CAZ-AVI group, COL group and combination group were -4.81±0.88, -7.06±0.69 and -9.70 (-9.78, -9.53), respectively. There were significant differences among the three groups (H = 33.601, P < 0.001), and between every two groups (adjusted P < 0.05). In time kill curves, the phytoplankton load of three XDR-PA decreased more than 6 log CFU/L when these two drugs were used together, and number of PA1819 planktonic bacteria decreased more than 5.1 log CFU/L compared with monotherapy group. Viable quantity in biofilm (A490) of normal saline group, CAZ-AVI group, COL group and CAZ-AVI-COL group were 0.665±0.068, 0.540±0.072, 0.494±0.642 and 0.317±0.080, respectively. There was significant difference between the other two groups (all P < 0.001), except for that between CAZ-AVI group and COL group (P = 0.109). Conclusions CAZ-AVI combined with COL can effectively improve the bactericidal effect of each drug alone on XDR-PA. The regimen can also reduce the production of drug-resistant bacteria and inhibit the formation of biofilm. Therefore, it is a potential treatment for XDR-PA infection.
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Objective To investigate the genetic characteristics of drug resistance and homology of extended-spectrum β-lactamase (ESBLs)-producing Klebsiella pneumoniae (Kpn) in hospitalized children in the pediatric intensive care unit (PICU) in Guiyang area.Methods The Kpn strains were collected from hospitalized children at 3 PICU from the Affiliated Hospital of Guizhou Medical University,Guizhou Provincial People's Hospital and Guiyang Children's Hospital from September 2014 to December 2016.Automatic bacteria identification instrument and Kirby-Bauer method were used to identify Kpn strains and confirm ESBLs phenotype respectively.The drug resistance genes were detected by using polymerase chain reaction (PCR),and their homology was analyzed by means of pulsed field gel electrophoresis (PFGE) and cluster analysis.Results (1) A total of 207 non-repetitive Kpn strains were isolated,of which 128 strains produced ESBLs (61.8％).There was no significant difference in the ESBLs detection rates among the different hospitals,years and types of samples (x2 =0.40,5.19,4.68,all P ＞ 0.05).(2) Among those 128 ESBLs-producing Kpn strains,123 strains (96.1％) were found to have drug-resistant genes,of which the detection rate of SHV type was the highest,accounting for 87.5％.These 3 drug resistance genotypes were distributed in 7 modes,of which 85.2％ were carrying more than 2 genotypes.(3) PFGE genotypic assay showed that there were 109 genotypes and 5 dominant clones.The PICU at 3 hospitals were all prevalent with type A strain,accounting for 14.8％.In 2015,there was a short-term outbreak of type A strain in Guiyang Children's Hospital.While,the resistance phenotypes of Kpn and the genotype of PFGE could both be consistent or different.Conclusions The ESBLs-producing Kpn at PICU in Guiyang area has the characteristics of multi-drug resistance,its drug-resistant genotypes have diversified,and there is a small-scale short-term outbreak epidemic,which poses a serious threat to clinical anti-infection treatment.It is necessary to strengthen clinical drug resistance monitoring and adopt effective infection control measures to prevent and control the spread of nosocomial infections.
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Background: Carbapenem resistance in Gram Negative Bacilli is an emerging threat in tertiary care centers which is mediated by Metallo-β-lactamase (MBL) enzyme. As per the National committee for Clinical Laboratory Standards (NCCLS), still does not have documented standard procedure from there several screening methods to detect their enzyme. Some subcontinents of India still awaiting to see prevalence and screening methods to detect enzyme which is responsible for Carbapenem Resistance. Aim: The present study was undertaken to early detection of MBL by screening methods in Gram Negative Bacilli isolated from hospital and the prevalence MBL production in carbapenem resistant bacterial isolates. Materials and methods: 176 consecutive different Gram Negative Bacilli (GNB) isolated from hospitalized patients which were tested antimicrobial susceptibility for different antibiotics including Carbapenem drugs as Imipenem by Kirby Bauer Disc Diffusion (CLSI 2010) and screening of Metallo-β-lactamase production by method as Imipenem- EDTA combined disc synergy test (ICDST) and Imipenem-Double Disc Synergy Test (I-DDST) which determine the MBL by zone size enhancement with EDTA Impregnated Imipenem. Munesh Kumar Sharma, Dakshina Bisht, Shekhar Pal. Detection of Metallo-β-lactamase producing Gram Negative Bacteria in clinical isolates in Tertiary care Hospital - A prospective study. IAIM, 2019; 6(4): 107-111. Page 108 Results: Out of 176 Gram Negative Bacilli, 20.45% (n=36) of isolates were resistance to Imipenem by disc diffusion method and 94.44% (n=34) by DDST EDTA impregnated Imipenem and 88.89% (n=32) showed enhancement of zone size ≥7 mm with EDTA impregnated Imipenem CDST. Imipenem susceptible bacteria strains did not show any enhancement with EDTA impregnated antibiotic disc. Conclusion: Critically ill patient’s therapy is cause of concern for MBL mediated imipenem resistance gram Negative Bacilli. Two methods used for supplementary support in treatment of patients. In both methods of detection DDST is more effective.
ABSTRACT
Non Fermenter Gram negative bacilli (NFGNB) has emerged as important hospital pathogens they are more significant as they are found to be multi drug resistant. Resistance to carbapenems is common among NFGNB. AIMS & OBJECTIVES: To isolate & identify NFGNB from various clinical samples and to detect resistance to carbapenem in isolates resistant to Imipenem. MATERIAL & METHOD: NFGNB isolated from various samples were speciated using standard tests. Isolates resistant to Imipenem were subjected to detection of MBLs(Metallo-β-lactmase) and Amp-C. RESULTS: Out of 1566 samples received, NFGNB were 200. Among them 112 were Pseudomonas aeruginosa from which 31 were found to be resistant to Imipenem, of which 3 were MBLproducer by Modified Hodge test while 4 were MBLproducer by EDTAdisc synergy test. Out of 200 NFGNB 71 were Acinetobacter baumanii, of which 23 were found to be resistant to Imipenem, of which 6 were MBLproducer by Modified Hodge test, while 4 were seen to be MBL producer by EDTAdisc synergy test. Nineteen isolates of Acinetobacter baumanii were found to be resistant to cefoxitin of which 6 were found to be Amp-C producer by Amp-c disc test. None of the Pseudomonas aeruginosa were Amp-C producer. Other NFGNB isolated were either sensitive to Imipenem or if resistant were not MBLor Amp-C producer.
ABSTRACT
The New Delhi metallo-β-lactamase-1 (NDM-1) was first reported in 2010, detected in a Klebsiella pneumoniae isolate from a Swedish patient of Indian origin. It has recently attracted extensive attention for its biological activities to catalyze the hydrolysis of almost all of β-lactam antibiotics. The gene for NDM-1 can spread from one strain of bacteria to another by horizontal gene transfer. The most troubling aspect is that there are currently no clinically available inhibitors to block the metallo-β-lactamase action. Therefore, there is urgent need to develop new NDM-1 inhibitors, which can protect β-lactam antibiotics from the hydrolysis effect of NDM-1. In this review, the current research, drug-assistant mechanism and potential NDM-1 inhibitors are summarized.