MBL Production Research Articles

In vitro potentiation of carbapenems with tannic acid against carbapenemase-producing enterobacteriaceae: exploring natural products as potential carbapenemase inhibitors

We hypothesized and confirmed that tannic acid (TA) reverses carbapenem resistance by inhibiting carbapenemases in class A and B carbapenemase-producing Enterobacteriaceae. Minimum inhibitory concentrations of carbapenems in the presence and absence of TA and other efflux pump inhibitors, TA-carbapenemases inhibition assays and computational studies showed that TA had the greatest effect on metallo-β-lactamases (MBLs) followed by class A serine-β-lactamases (SBLs). TA completely reversed the MICs of MBL producers from between 32 and ≥512mgl-1 to susceptible values (<4mgl-1 ) while substantially reducing the MICs of SBLs from between 16 and >512mgl-1 to <4 to 16mgl-1 . Tolerable cytotoxic effect was observed for the concentrations tested (8-1024mgl-1 ). TA inhibited enzymes with a marked difference of ≈50% inhibition (IC50 ) for NDM-1 (270μmoll-1 ) and KPC-2 (15 μmoll-1 ). TA inhibited both MBLs and SBLs by targeting their hydrophobic sites. Moreover, TA had a stronger binding affinity for MBLs than SBLs as the MBLs, specifically VIM-1 (-43·7220±0·4513kcalmol-1 ) and NDM-1(-44·2329±0·3806kcalmol-1 ), interact with a larger number of their catalytic active-site residues than that of OXA-48 (-22·5275± 0·1300kcalmol-1 ) and KPC-2 (-22·1164±0·0111kcalmol-1 ). Tannic acid or its analogues could bedeveloped into carbapenemase-inhibiting adjuvants to restore carbapenemactivity in CRE infections, save many lives and reduce healthcare associated costs.

Prevalence of Extended Spectrum Beta Lactamases (ESBL) and Metallo Beta Lactamases (MBL) Mediated Resistance in Gram Negative Bacterial Pathogens

Objectives: This study was conducted to determine the prevalence of multi-drug resistance (MDR) along with Extended Spectrum β-lactamase (ESBL) and Metallo β-lactamase (MBL) producing gram negative bacterial isolates among the patients attending Shahid Gangalal National Heart Centre, Kathmandu, Nepal.Methods: This cross-sectional study was carried out from June to December; 2016. Altogether 977 clinical specimens were processed for analysis of bacteriological profile and the isolates were identified by culture, morphological and biochemical tests. Antibiotic susceptibility testing of the isolates was performed by Kirby Bauer disc diffusion methods following Clinical and Laboratories Standard Institute guideline and the isolates were tested for ESBL and MBL by combined disk method.Results: out of 977 clinical specimens, 254 (25.99%) were found to be gram negative bacterial isolates, among them Klebsiella pneumoniae 83 (32.67%) was the most predominant organism followed by E. coli 51 (20.07%), Pseudomonas aeruginosa 36 (14.17%), K. oxytoca 32 (12.59%), Proteus mirabilis 13 (5.11%) and P. vulgaris 13 (5.11%), Acinetobacter spp. 11 (4.33%), Citrobacter spp. 10 (3.93%) and Enterobacter spp. 5 (1.96%) respectively. 83 (32.67%) isolates were found to be MDR, 38(14.96%) were positive for ESBL while 19 (7.48%) were MBL producer.Conclusion: The determent drug resistance among ESBL and MBL producers, reflect the extensive use of antibiotics possessing difficulties in therapeutic potions in hospital setting which might be overcome by proper microbiological analysis of pathogenic isolates and judicious use of antibiotics for emergence of resistance strains.

Phenotypic Assays for Detection of AmpC and MBL Producers among the Clinical Isolates of Multi Drug Resistant Pseudomonas aeruginosa

Objectives: In order to determine the prevalence of multi-drug resistance along with AmpC and metallo-β-lactamase producing P. aeruginosa, a six month cross-sectional study was carried out at Shahid Gangalal National Heart Center.Methods: A total of 756 clinical specimens were analyzed for bacteriological profile. The bacterial isolates were identified by cultural and biochemical techniques. Antibiotic susceptibility testing of the isolates was performed by Kirby-Bauer disc diffusion method. MDR isolates were screened and tested for MBL and AmpC production. Ceftazidime resistant isolates were tested for MBL and Cefoxitin resistant isolates for AmpC.Results: Among all the clinical samples analyzed, P. aeruginosa was detected in 75 samples (9.92%). Antibiotic susceptibility testing showed Imipenem as the most effective drug with susceptibility of 76% followed by Piperacillin-Tazobactam (74.7%) and Piperacillin (41.3%). Out of 75 P. aeruginosa isolates, 53 (70.6%) of them were found to be resistant to at least three out of four anti-pseudomonal agents, thus were considered as MDR. Out of 53 multi-drug resistant P. aeruginosa (MDRPA), all were resistant to ceftazidime whereas 85% (45/53) were resistant to cefoxitin. Out of 53 isolates, 11 (20.75%) showed positive result for MBL. Similarly, 7 out of 45 i.e. 13.2% were found to be AmpC producers.Conclusion: This study signified the high prevalence of MDRPA which is an alarming rate. Also multiple β-lactamase producing P. aeruginosa were detected which can further complicate the treatment options. Regular monitoring of antibiotic susceptibility and rational use of antibiotics would be helpful in eliminating the outbreaks of multiple β-lactamase producing MDRPA.

Detection of Metallo-Beta-Lactamase-Encoding Genes Among Clinical Isolates of Pseudomonas aeruginosa in Qom Province

Background: Carbapenem-resistant Pseudomonas aeruginosa has emerged as a serious problem in many hospitals and intensive care units. The purpose of this study was to determine the antibiotic susceptibility profile and the distribution of metallo-beta-lactamase genes among P. aeruginosa isolates from Qom province of Iran. Methods: In this study, 200 P. aeruginosa isolates were collected from several clinical samples in hospitals affiliated to Qom University of Medical Sciences, Qom province, Iran. The antibiotic susceptibility of the isolates was tested by the Kirby-Bauer disc diffusion test and the distribution of MBL genes among carbapenem-resistant isolates was determined by polymerase chain reaction (PCR) method. Results: Among carbapenem non-susceptible isolates of P. aeruginosa, 38% (76 isolates) were multidrug resistant, 26% (52 isolates) were pan-drug-resistant and 5% (10 isolates) were extensive drug resistant. 52% of the isolates were resistant to carbapenems. Among carbapenem non-susceptible isolates of P. aeruginosa, 40 isolates (38.4%) exhibited MBL production. Of 40 MBL-producing isolates, 38 isolates (36.5%) contained the blaIMP gene and two (1.9%) isolates contained the blaVIM gene. Conclusions: Outbreaks of MBL-producing P. aeruginosa isolates will be a serious problem in hospitals in the future and rapid identification of these isolates is necessary to control further dissemination of MBL resistance genes. This is the first report of the rates of MDR, XDR, PDR, and MBL-producing P. aeruginosa isolated from hospitals affiliated to Qom University of Medical Sciences in Qom province of Iran.

Phenotypic and molecular detection of metallo-β-lactamase-producing Pseudomonas aeruginosa isolates from patients with burns in Tehran, Iran.

Health care-associated infections caused by metallo-β-lactamase (MBL)-producing Pseudomonas aeruginosa are a significant growing concern in patients with burns worldwide. The aims of this study were to determine the antibiotic susceptibility of and detect the presence of MBLs among P. aeruginosa isolates and assess their clonal relationship using enterobacterial repetitive intergenic consensus (ERIC)-PCR. Non-duplicated clinical isolates (160) of P. aeruginosa were collected from patients with burns at the Motahari Hospital in Tehran, Iran. All isolates were identified using standard laboratory methods and further characterized for antimicrobial susceptibility. Any carbapenem-resistant isolates were then examined for MBL production by the E-test and MBL-encoding genes were detected by PCR. The clonal relatedness of MBL-producing isolates was assessed by ERIC-PCR. For multidrug-resistant isolates, the highest rates of susceptibility were observed for colistin 160 (100%), polymyxin B 160 (100%), and ceftazidime 32 (20%). In total, 69 (43.7%) isolates were identified as MBL producers. Twenty-eight (17.5%) isolates were positive for the bla VIM-1 gene followed by the bla IMP-1 (15.6%) and bla SPM-1 (5.6%) genes. ERIC-PCR revealed three separate genotypes, where type A (76.8%) was the most prevalent, followed by B (20.3%), and then C (2.9%). Our present study found that the bla IMP-1 and bla VIM-1 genes were present at a significant frequency and also detected the bla SPM-1 gene in P. aeruginosa isolates for the first time, highlighting the need for establishing suitable infection control measures to successfully treat patients and prevent further spread of these resistant organisms among patients with burns.

High rate of carbapenem-resistant Klebsiella pneumoniae detected from hospital equipments in Iran.

The objective of this study was to assess the prevalence, antibiogram, and related genes of carbapenem-resistant Klebsiella pneumoniae (CRKP) among hospital environment samples. A total of 250 samples were taken from different surfaces and medical devices of three hospitals in Isfahan, Iran. All samples were cultured and K. pneumoniae strains were identified by conventional microbiological methods and polymerase chain reaction (PCR). Antibiogram of isolates was performed by disk diffusion method and production of carbapenemases and metallo-β-lactamases (MBLs) was confirmed using modified Hodge test and E-test, respectively. Molecular detection of the related genes was carried out by PCR. Overall, 37 (14.8%) K. pneumoniae strains were isolated, of which 34 (91.9%) strains were resistant to carbapenems. Twenty-eight (82.4%) isolates were positive for carbapenemases and seven (20.6%) isolates were phenotypically MBL producers. The results of PCR showed that the prevalence of blaOXA-48, blaNDM, blaIMP, blaSHV, blaCTX-M, blaTEM, and class 1 integron among CRKP isolates was 70.6%, 52.9%, 2.9%, 100%, 82.4%, 55.9%, and 76.5%, respectively. However, blaKPC, blaGES, blaIMI, blaVIM, and class 2 integron were not detected in any of the isolates. This study showed that the environment of our hospitals is contaminated with CRKP and it emphasizes the importance of using standard methods for infection control.

Prevalence of VIM- and GIM-producing Acinetobacter baumannii from patients with severe urinary tract infection.

Carbapenems are administered as the final drug of choice for treating complicated nosocomial infections caused by multidrug-resistant Acinetobacter baumannii strains. It is currently a worldwide issue that metallo-β-lactamases (MBLs) as carbapenem-hydrolyzing enzymes are one of the major drug resistance mechanisms. This investigation is thus aimed to assess the prevalence and characterize the MBL-producing strains of A. baumannii both by phenotypic assays and by genotypic characterization. A total of 73 isolates of A. baumannii were phenotypically and genotypically characterized from patients (N = 1,000) with severe urinary tract infection. Tested strains were subjected to double disc synergy testing (DDST) by Kirby-Bauer disc diffusion method with imipenem (IMP) and IMP/EDTA combination discs. Plasmid DNA was molecularly screened for MBL-encoding blaIMP, blaVIM, blaGIM, and blaNDM genes by PCR for the genetic relatedness of the MBL genes with carbapenem resistance. Carbapenem resistance profile showed 100%, 45%, and 49% non-susceptibility against imipenem, doripenem, and meropenem, respectively. Altogether 42.46% (n = 31) of the isolates showed MBL production upon double disc phenotypic test with IMP and IMP/EDTA discs. The blaVIM and blaGIM were detected in 34.24% (n = 25) and 16.43% (n = 12) of the isolates, respectively, while the co-occurrence of blaVIM and blaGIM was 2.73% among the isolates. DDST-positive isolates showed 21.19% and 9.58% strains positive for blaVIM and blaGIM, respectively, whereas 1.36% of the strains for both genes. None of the strains yielded blaIMP and blaNDM genes. The findings of this study showed prevalence of carbapenem resistance among A. baumannii from urine samples and the frequency of blaVIM and blaGIM.

Effect of sodium mercaptoacetic acid on different antimicrobial disks in the sodium mercaptoacetic acid double disk synergy test for detection of IMP-1 metallo-β-lactamase-producing Pseudomonas aeruginosa isolates in Japan

We determined the optimal antimicrobial in the sodium mercaptoacetic acid double disk synergy test (SMA-DDST) for the detection of IMP-1-producing Pseudomonas aeruginosa isolates in Japan and evaluated the performance of the test. Fifty-four P.aeruginosa clinical isolates were tested, including 39 IMP-1 producers and 15 non-metallo-β-lactamase (MBL)-producing carbapenem- and ceftazidime (CAZ)-resistant isolates. The SMA-DDST was performed with CAZ, cefepime (CFPM), imipenem (IPM), meropenem (MEPM), doripenem (DRPM), or biapenem (BIPM)-containing disks. The sensitivity of the SMA-DDST with CAZ, CFPM, IPM, MEPM, DRPM, and BIPM was 39/39 (100%), 36/39 (92%), 18/39 (46%), 8/39 (21%), 19/39 (49%), and 36/39 (92%), respectively. The specificity was 15/15 (100%) for all SMA-DDSTs. This suggests that the isolates may have a resistance mechanism other than MBL production for IPM, MEPM, or DRPM. Since the CAZ resistance mechanism in P.aeruginosa is the same as that of CFPM, but differs from that of carbapenems, we conclude that combining CAZ with BIPM SMA-DDSTs can prevent any failure in the detection of IMP-1-producing P.aeruginosa.

Carbapenem resistance in bacteria isolated from soil and water environments in Algeria.

Recent research has demonstrated that natural populations of bacteria carry large numbers of mobile genetic elements that may harbour antibiotic resistance determinants. This study aimed to investigate carbapenem resistance in Gram-negative bacteria isolated from natural environments in Béjaïa (Algeria) and to determine the horizontal gene transfer potential of a subset of these antibiotic resistance genes (ARGs). Antibiotic-resistant bacteria were isolated and the host was identified using MALDI-TOF/MS and 16S rRNA sequencing. ARG carriage was investigated by the double-disk synergy test, metallo-β-lactamase (MBL) production test and PCR screening for carbapenemase genes. Conjugation experiments were performed to determine potential ARG mobility. To identify ARGs, genomic libraries were constructed and functionally screened and inserts were sequenced. A total of 62 antibiotic-resistant strains isolated from soil and water samples were classified as belonging to the Enterobacteriaceae, Pseudomonadaceae, Xanthomonadaceae and Aeromonadaceae families. Four highly imipenem-resistant (MIC>64μg/mL) and cefotaxime-resistant (MIC>8μg/mL) clinically-relevant strains were selected for further characterisation. All four strains produced extended-spectrum β-lactamases, but MBL production was not confirmed. Imipenem and cefotaxime resistance was transferable to Escherichia coli but was not conferred by blaAmpC, blaIMP, blaNDM, blaKPC, blaOXA-48 or blaGES genes. Novel putative resistance mechanisms were identified, including a novel DHA β-lactamase conferring clinical resistance to cefotaxime. The environment is a reservoir of carbapenem-resistant bacteria. Further investigation of the evolution and dissemination of antibiotic resistance in environmental bacteria is required in order to understand and prevent the emergence of resistance in the clinical environment.

Prevalence and antibiotic sensitivity profiles of bacteria causing community acquired pneumonia in Rawalpindi, Pakistan

Background: Despite the availability of potent new anti-microbial agents and vaccines, Community Acquired Pneumonia (CAP) remains a common and serious problem especially for developing nations. The microbial etiological agents and their resistant patterns vary widely. Irrational and unnecessary use of antibiotics, changes in environment, changes in lifestyle and increased mobility of the people have contributed to changes in the patterns of microbial profiles and their resistant patterns in the different communities. Unfortunately, there have been very few studies done regarding etiology of CAP, prevalence of causative organisms and their resistance pattern in Pakistan. Thus it was quite crucial to detect them in our context. Methods & Materials: A descriptive cross-sectional study conducted over a period of one year (April 2016–April 2017) on 750 clinically diagnosed CAP patients visiting OPD of Holy Family Hospital, Rawalpindi. Sputum samples that met the acceptance criteria were further processed according to the standard methodology. Results: Bacterial etiologies could be identified only in 45.5% of cases of CAP. Haemophilus influenzae (36.8%), Streptococcus pneumoniae (28.5%) and Pseudomonas aeruginosa (21.6%) were the commonest bacterial etiologies, Twenty-nine percent of H. influenzae isolates were MDR. The prevalence of MDR bacteria in CAP patients was 52.44%. Among gram-negative bacterial isolates, the highest number of MDR was seen in Pseudomonas aeruginosa, followed by Klebsiella pneumoniae, E. coli and Acinetobacter spp. The prevalence of ESBL, AmpC and MBL producing gram-negative bacteria were 12.5% (more common among Klebsiella pneumoniae (18.56%), 7.9% and 5.8% (more common among Acinetobacter spp (16.32%) respectively. Conclusion: Different bacteria are responsible for CAP in our setting. MDR, ESBL, MBL and AmpC producing bacterial strains are present in our community also. Thus it has demanded to take special care during treatment of patients with community acquired infections also and also sought for other similar type of extensive studies on large number of community isolates to characterize their genetic relatedness and resistant patterns so that appropriate measures can be applied.

Performance evaluation of the MALDI Biotyper Selective Testing of Antibiotic Resistance–β-Lactamase (MBT STAR-BL) assay for the detection of IMP metallo-β-lactamase activity in Enterobacteriaceae

The MALDI Biotyper Selective Testing of Antibiotic Resistance–β-Lactamase (MBT STAR-BL) assay enables rapid detection of β-lactamase activity using matrix-assisted laser desorption ionization–time-of-flight mass spectrometry. The assay is based on analysis of bacterially induced hydrolysis of β-lactam antibiotics. We investigated the performance of the MBT STAR-BL assay for detecting IMP metallo-β-lactamase (MBL) activity in Enterobacteriaceae. A total of 145 strains (30 Escherichia coli, 43 Klebsiella pneumoniae, and 72 Enterobacter cloacae complex) were evaluated using meropenem hydrolysis assays. The MBT STAR-BL correctly identified all 48 IMP MBL producers as positive, even those exhibiting a low minimal inhibitory concentration (MIC) (1 μg/mL) for meropenem. Conversely, all non–IMP MBL producers, including strains with higher MICs (4 or 8 μg/mL), were correctly identified as negative. The MBT STAR-BL is a rapid, accurate, and reliable system for detecting IMP MBL activity in Enterobacteriaceae.

Susceptibility Pattern of Fosfomycin Against Drug Resistant Bacteria Obtained from Non - Urinary Clinical Samples in a Tertiary Care Hospital, South India

Background: Multi drug resistance (MDR) in bacterial infections has been an ever growing problem worldwide. To combat this some of the old drugs like fosfomycin used in the past are revived. The aim of our study was to determine the susceptibility of fosfomycin against Methicillin sensitive and Resistant Staphylococcus aureus, ESBL producing Escherichia coli, Klebsiella species and Metallo Beta Lactamase producing Pseudomonas aeruginosa isolated from the specimens other than urine and to evaluate the agreement between the two methods, disk diffusion and agar dilution methods performed as per CLSI guidelines. Methods: First isolate of each species per patient (n=250) were tested for susceptibility to fosfomycin concomitantly by the disk diffusion and agar dilution methods described by CLSI guidelines and comparison of the two methods were studied. Result: Staphylococcus aureus and ESBL E. coli were showing 100% susceptibility, Whereas ESBL producing Klebsiella species showed 88% susceptibility to fosfomycin 200 µg/disc and 80% and 72% by agar dilution method as per CLSI and EUCAST criteria. For MBL producing Pseudomonas aeruginosa, 90% isolates were susceptible to fosfomycin 200 µg/disc and in agar dilution (60%) (≤32µg/ml) were susceptible as per EUCAST criteria. Disk diffusion method showed good agreement for S.aureus and E.coli whereas moderate agreement for Klebsiella species and very poor for Pseudomonas aeruginosa. Conclusion: Fosfomycin can be considered as an alternate drug to treat infections with multi drug resistant bacteria, not only for the UTI but for systemic infections also. This is achievable with establishment of breakpoint values and zone diameter for all common isolates.

MBL2 gene polymorphism rs1800450 and rheumatic fever with and without rheumatic heart disease: an Egyptian pilot study

BackgroundRheumatic fever (RF) is the result of an autoimmune response to pharyngitis caused by infection with Streptococcus pyogenes. RF is most prevalent in Africa and the Middle East. Rheumatic heart disease (RHD) is the most serious complication of RF. Mannose-binding lectin 2 gene (MBL2) has been reported to be correlated with different cardiac conditions. In Egyptian patients as a new studied ethnic population, it is the first time to evaluate the association between MBL2 gene polymorphism rs1800450 and RF with and without RHD.MethodsOne hundred and sixty RF patients (80 with RHD and 80 without RHD) and eighty healthy ethnically matched controls were studied. MBL2 (rs1800450) was genotyped by real-time PCR using TaqMan® allele discrimination assay. The MBL level was measured by ELISA. Westergren erythrocytes sedimentation rate (ESR), anti-streptolysin O titer (ASOT), C-reactive protein (CRP) and complements (C3 and C4) were determined.ResultsThe AA genotype with high production of MBL was associated with increased risk of RHD more than the B allele carrying subjects. However, MBL2 genotype related to the low production of MBL was more frequently observed in those patients without RHD.ConclusionsOur results suggested the involvement of MBL2 (rs1800450) polymorphism and its protein in RHD pathogenesis. Also, it might be a promising future strategy to utilize this polymorphism to help differentiate patients with RHD from those without RHD.

Phenotypic Identification, Frequency Distribution and Antibiogram of Carbapenemase Producing Enterobacteriaceae in Clinical Isolates.

To differentiate between Ambler class A, B and D of carbapenemase-producing Enterobacteriaceae by using simple phenotypic methods that can be carried out in the laboratory without requiring any specialised techniques. Cross-sectional study. Microbiology Department, Army Medical College, NUST, Islamabad, from November 2015 to November 2016. Clinical specimens were subjected to identification of Enterobacteriaceae by colony morphology and API 20 E. Carbapenem resistance was detected by applying meropenem disc (10 µg) by disc diffusion method according to CLSI (Clinical Laboratory Standard Institute) criteria. Carbapenemase production among Enterobacteriaceae was detected by Modified Hodge test. Phenotypic methods, Phenylboronic acid (for Class A KPC producing Enterobacteriaceae) and EDTA inhibition tests (for Class B MBL producing Entrobacteriaceae) were applied. Presence of OXA 48 was detected by phenotypic method using imipenem 10 µg, EDTA and PBA discs. Antibiotic susceptibility was determined by Kirby-Bauer disc diffusion method. Forty-three out of 45 (95.45%) were carbapenemase producers. Thirty-eight out of 43 (88.3%) were KPC producers and 4 out of 43 (11.62%) were MBL producers. All KPC producers were Klebsiella pneumoniae. Among five MBL producers, one each (20%) was Enterobacter cloacae and Escherichia coli and 3 (60%) were Klebsiella pneumoniae. All MBL producers were resistant to aztreonam and amoxicillin/clavulanate. Two of the KPC producing Klebsiella pneumoniae were pan-drug resistant (resistant to colistin and tigecycline). Two were non-carbapenemase producers. Enterobacteriaceae strains producing KPC-type carbapenemase were the most prevalent (88.3%) in the studied healthcare setup.

Occurrence of bla genes encoding carbapenem-resistant Pseudomonas aeruginosa and Acinetobacter baumannii from Intensive Care Unit in a tertiary care hospital.

CONTEXT:ICU shows increasing incidence of infection associated with the use of invasive procedures for the diagnostic purpose as well as the indiscriminate use of antibiotics. Pseudomonas aeruginosa and Acinetobacter species are “very successful” pathogen and the emergence of the Metallo-β-Lactamases (MBL) is becoming a therapeutic challenge.AIMS:To isolate the Nonfermenting Gram negative bacilli from the ICU samples. To identify the metallo betalactamase producers and to detect the bla gene presence among the Pseudomonas aeruginosa and Acinetobacter baumannii.SETTINGS AND DESIGN:The Nonfermenting Gram negative bacilli isolates from the ICU samples were taken over for 5 years (2009-2014) in a tertiary care hospital.METHODS AND MATERIALS:The isolates of Pseudomonas species and Acinetobacter species were confirmed by API analyser and processed according to standard procedures. Detection of the MBL producers were done by E strip method and subjected for bla gene detection by PCR method.RESULTS:In our study a total of 195 isolates of NFGNB were obtained from various ICU. Of these MBL producers, 26 % were Pseudomonas aeruginosa and 25 % were Acinetobacter baumannii. The subtypes of blaVIM MBL producing P.aeruginosa were 26%. The predominant gene coding for MBL activity in A.baumannii were found to be blaOXA gene 11.9%. The gene accession numbers were KF975367, KF975372.CONCLUSIONS:We have to control the development and dissemination of these superbugs among the ICU's.

Molecular epidemiology and clonality of Acinetobacter spp in a Lebanese hospital over a period of one year.

The worldwide emergence of antimicrobial resistance in Acinetobacter spp and their clonal dissemination call for the investigation into Acinetobacter spp epidemiology. 100 nonrepetitive Acinetobacter spp isolates were recovered from patients admitted at Saint- George-Hospital-University-Medical-Center-Beirut, in a one-year period. Identification of the isolates was determined by the API20NE and confirmed by PCR amplification of blaOXA-51-like. Susceptibility to carbapenems and colistin were determined by the microdilution method and interpreted according to the CLSI, 2015.The β lactamase inhibitors: PBA, EDTA, and Cloxacillin were used for the detection of KPC, MBL and AmpC, respectively. ESBL producers were detected whenever a keyhole effect was observed between 3rd generation cephalosporin and Augmentin®. Simplex PCR was conducted for the genotypic detection of β lactamases. ERIC and 3LST-PCR were performed to determine the clonality of the isolates. Our findings showed that 84% were carbapenem resistant. Only one isolate was resistant to colistin. Phenotypically, 23 were ESBL, 15 KPC, 5 AmpC, and 4 MBL producers. PCR analysis showed that 99%, 93%, 77% and 3 % of the isolates harbored blaOXA-51-like, blaADC, blaOXA-23-like, and blaOXA-40-like, respectively. ERIC-PCR analysis showed that A.baumannii isolates were clustered in 19 possibly related and 30 closely related subtypes. The 3-LST-PCR showed that 86.2% of the A.baumannii isolates pertained to the ICII (international clone II). Our study showed a predominance of OXA-23-like producers and dissemination of ICII. Inhibitor based method was shown not to be accurate for the prediction of carbapenemases in Acinetobacter spp. Infection control measures are needed for management of Acinetobacter spp infections.

Molecular characterization of carbapenem-resistant &lt;i&gt;Acinetobacter baumannii&lt;/i&gt; isolated from pediatric burns patients in an Iranian hospital

Purpose : To survey the molecular characteristics of imipenem-resistant Acinetobacter baumannii obtained from pediatric burns patients in a teaching hospital in Tehran, Iran. Methods : Over a 10-month period, 73 non-duplicate A. baumannii strains were collected from pediatric burns patients admitted to Motahari Burn and Reconstruction Center, Tehran, Iran. The resistance profile of several antimicrobials was determined. Metallo-β-lactamase (MBL)-producing isolates were identified using double-disk synergy and an MBL E-test. Polymerase chain reaction (PCR) was carried out to detect the following β-lactamase-encoding elements: blaVIM, blaIMP, blaSIM, blaSPM, blaGIM, blaNDM, blaAIM, blaDIM, blaKPC, blaOXA-23/24/51, and blaOXA-58. The types of integrons were also identified using PCR. Results : Out of the 73 collected strains, 92.4 and 38.3 % of the isolates were multidrug-resistant (MDR) and extensively drug-resistant (XDR), respectively. Colistin was the most effective antibiotic. It was found that 94.5 % of the strains were resistant to imipenem, as determined both by disk agar diffusion and MIC E-test methods. Based on double disk synergy and E-test, 78.1 and 83.5 % of the isolates, respectively, were MBL producers. The prevalence of blaOXA-23 and blaOXA-24 were 75.4 and 39.1 %, respectively. The results also indicate that 62.3, 30.4, and 4.3 % of the isolates were positive for blaVIM, blaIMP and blaNDM genes, respectively. Furthermore, 16.4, 76.1, and 7.5 % of the isolates carried intI, intII, and intIII genes, respectively. Conclusion : The increased frequency of carbapenem-resistant A. baumannii in burns cases underlines the importance of choosing an appropriate antibacterial regimen based on antibiotic susceptibility profile. Rapid identification of carbapenemase-producing strains would be helpful for selecting suitable antimicrobial therapy and preventing further spread of their encoding genes. Keywords : Carbapenem-resistant Acinetobacter baumannii, Pediatric burns, Integron, β-lactamase genes

Mannose-Binding Lectin2 Gene Polymorphism and IgG4 in Membranous Nephropathy

Background: Idiopathic membranous nephropathy (IMN) has been linked to the lectin pathway, IgG4 and genetic susceptibility. We investigated the frequency of mannose-binding lectin2 (MBL2) gene polymorphisms and the serum ratio of IgG4 in patients with membranous nephropathy (MN). Methods: Polymorphisms in the exon 1 of the MBL2 gene (codons 52, 54, and 57) and single base polymorphisms at positions –550 (HL) and –221 (XY) in the promoter region were evaluated in 60 patients compared to a control group (CG) of 101 blood donors. It established the frequency of polymorphisms and the serum ratio of IgG4 comparing 2 etiologies of MN: idiopathic (35 patients) and secondary to systemic lupus erythematosus (25 patients). Results: Patients with MN had a 2.54-fold higher probability (95% CI 1.51–4.31) of carrying the O alelle, exon 1 variant, and 11.16-fold higher probability (95% CI 4.77–28.41) of having A/O genotype when compared to CG. The frequency of polymorphisms in the promoter region was similar between the groups. Combined genotypes generally related to the defective production of MBL (YA/O, XA/O and O/O) were more frequent in patients with MN (OR 7.11; 95% CI 2.69–21.27), when compared to controls. The median of serum ratio IgG4 was 5% for idiopathic MN and 3% for lupus MN patients (p = 0.016). Conclusions: Our data suggests that MBL2 polymorphisms may be associated with the activation of the lectin pathway by IgG4 subclass antibodies in MN.

Chronic infection sustained by a Pseudomonas aeruginosa High-Risk clone producing the VIM-1 metallo-β-lactamase in a cystic fibrosis patient after lung transplantation

BackgroundThe significance of chronic lung infection by multidrug-resistant (MDR) pathogens in Cystic Fibrosis (CF) transplanted patients remains controversial, and the available information is overall limited. Here we describe the case of a chronic infection, sustained by a metallo-β-lactamase (MBL)-producing P. aeruginosa strain, in a CF patient following lung transplantation. MethodsTwelve P. aeruginosa isolates collected from a CF patient over a 15-years follow-up period after lung transplantation were analysed for their antibiotic susceptibility profile, MBL production and clonal relatedness. Available clinical and microbiological records were reviewed. ResultsThe transplanted CF patient was chronically infected by an MBL-producing P. aeruginosa strain which harboured a blaVIM-1 determinant inserted into a novel class 1 integron. The strain exhibited an MDR phenotype and belonged to the globally widespread ST235 epidemic clonal lineage, which however is not a typical CF-associated epidemic clone. Despite the chronic infection, the long-term outcome of this patient during the post-transplant period was characterized by the absence of acute exacerbations and by a mostly stable pulmonary function. ConclusionsThis report provides one of the few descriptions of MBL-producing P. aeruginosa infections in CF patients, and the first description of such an infection after lung transplantation in these patients. Infection with the MBL-producing strain apparently did not significantly affect the patient pulmonary function.

Detection of VIM-2-, IMP-1- and NDM-1-producing multidrug-resistant Pseudomonas aeruginosa in Malaysia.

The increasing incidence of carbapenem-resistant Pseudomonas aeruginosa along with the discovery of novel metallo-β-lactamases (MBLs) is of concern. In this study, the isolation of MBL-producing P. aeruginosa clinical strains in Malaysia was investigated. A total of 53 P. aeruginosa clinical strains were isolated from different patients in Sultanah Aminah Hospital (Johor Bahru, Malaysia) in 2015. Antimicrobial susceptibility testing was performed, and minimum inhibitory concentrations (MICs) of imipenem and meropenem were determined by Etest. Carbapenem-resistant strains were screened for MBL production by the imipenem-ethylene diamine tetra-acetic acid (IMP-EDTA) double-disk synergy test, MBL imipenem/imipenem-inhibitor (IP/IPI) Etest and PCR. Multilocus sequence typing (MLST) analysis was performed for genotyping of the isolates. Among the 53 clinical strains, 3 (5.7%) were identified as MBL-producers. Multidrug resistance was observed in all three strains, and two were resistant to all of the antimicrobials tested. Sequencing analysis confirmed that the three strains harboured carbapenemase genes (blaIMP-1, blaVIM-2 and blaNDM-1 in one isolate each). These multidrug-resistant strains were identified as sequence type 235 (ST235) and ST308. The blaIMP-1 and blaNDM-1 genes have not previously been reported in Malaysian P. aeruginosa isolates. The emergence of imipenemase 1 (IMP-1)- and New Delhi metallo-β-lactamase 1 (NDM-1)-producing P. aeruginosa in Malaysia maybe travel-associated.