Metallo-beta-lactamase Producers Research Articles

Utility of phenotypic methods in detection of metallo-beta-lactamases in gram-negative bacteria

Background: Metallo-beta-lactamases (MBLs)-producing Gram-negative bacilli (GNB) are one of the significant multidrug-resistant pathogens causing healthcare-associated infection (HAI) worldwide. The present study aimed to compare the phenotypic and molecular methods to detect MBLs-producing GNB causing HAI, namely Acinetobacter baumannii, Escherichia coli, Klebsiella pneumoniae, and Pseudomonas aeruginosa in a tertiary care hospital. Materials and Methods: Antimicrobial susceptibilities were determined for 232 isolates identified during 8 months period, and the Modified Hodge Test confirmed carbapenemases production in carbapenem-resistant isolates as per the Clinical and Laboratory Standards Guidelines 2013. MBLs production was detected by the disc enhancement test (DET), combined disk test (CDT), and polymerase chain reaction (PCR) and statistically analyzed. Results: One hundred (43.1%) isolates were found to be carbapenem-resistant, of which 85% were positive on the Modified Hodge Test. The DET was 96.67%, whereas the CDT was 93.33% sensitive as compared to the PCR. Kappa coefficient ranged from 0.918 to 0.959 for different methods indicating the excellent agreement between the three methods. Conclusion: The DET and CDT showed excellent agreement with molecular methods to detect MBLs-producing isolates. They are easy to perform, inexpensive, and can be routinely used in clinical laboratories.

Reasonable Detection Tests of Metallo Beta-Lactamases and Oxacillinases Products in Carbapenem-Resistant Acinetobacter Strains

Acinetobacter baumannii (A. baumannii) is suggested to be common cause infection and outbreaks. Carbapenems are often used as antibiotics of last resort for treating infections caused by A. baumannii. Metallo beta-lactamases (MBL) are liable for carbapenem resistance, as well as oxacillinases (OXA). A total of 70 non-repetitive imipenem and meropenem resistant Acinetobacter species were isolated from clinical samples. The VITEK-2 system was used for species identification and detection of antibiotic susceptibility. This was followed by modified Hodge test (MHT) and combined disc diffusion test (CDDT) for phenotypic detection of carbapenemase (also referred to OXA-like) and metallo-β-lactamase enzyme production, respectively. 92.8 % of the A. baumannii isolates were carbapenem-resistant, of which 100% were carbapenemase producers by MHT, and only 15.4% were metallo-β-lactamase producers by CDDT. PCR was used to detect carbapenemase genes (blaOXA-23, blaOXA-24, blaOXA- 51, and blaOXA-58). Our data showed that resistance to carbapenems is due to the presence of blaOXA-23, blaOXA-58 and blaOXA-24 genes. Resistance to imipenem was found to be a better indicator of MBL production. IPM-EDTA disk synergy test appears to be useful in differentiating MBL and non-metalloenzyme producers. During this study, we reported a reasonable detection tests of MBL and OXA producing species as a crucial step for an efficient infection control policy and may to prevent their uncontrolled spread in clinical settings.

Phenotypic and genotypic detection of metallo-B-lactamases producing Pseudomonas aeruginosa: A study done in two university hospitals

<br><b>Background</b><br>Metallo-beta-lactamase (MBL) producing <i>Pseudomonas aeruginosa </i>has emerged as a threat to hospital-infection control due to its multidrug resistance, but the laboratory detection of these strains is not well defined.<br><b>Objectives</b><br>Screening for MBL production from <i>P. aeruginosa </i>isolates from different clinical specimens using different phenotypic and genotyping techniques. In addition, we aim to apply a PCR test for genetic confirmation of MBL producers.<br><b>Patients and methods</b><br>We used EDTA-disk screen test and molecular diagnostic assay for the detection of MBL-producing <i>P. aeruginosa </i>isolated from different clinical specimens collected in Kasr Alainy and Fayoum University Hospitals. Using Clinical and Laboratory Standards Institute-disk methodology, inhibition-zone diameters were determined in tests with imipenem (IPM) and meropenem disks alone and in combination with 750 μg of EDTA. This test was compared with the MBL E-test. Detection for MBL-production genes (<i>blaIMP</i> and <i>blaVIM</i>) was done using PCR.<br><b>Results</b><br>Of the 50 clinical strains of IPM nonsusceptible <i>P. aeruginosa</i>, 32/50 (64.0%) were MBL positive using disk-diffusion methods, 26/50 (52.0%) were positive for MBL by E-test, while 17/50 (34.0%) were positive for MBL genes: 17/50 (34.0%) for <i>blaVIM</i> and 0/50 (0%) for <i>blaIMP</i>. The EDTA disk-screen test using IPM showed 100% sensitivity and 54.5% specificity for detecting MBLs in clinical strains. While E-test showed 100% sensitivity and 69.7% specificity.<br><b>Conclusion</b><br>The EDTA disk-screen test was simple to perform and to interpret and can easily be introduced into the workflow of a clinical laboratory. We recommend that all IPM nonsusceptible <i>P. aeruginosa</i> isolates be routinely screened for MBL production using the EDTA disk-screen test and PCR confirmation be performed at a regional laboratory.<br>

Phenotypic characterization of beta-lactamases producing Gram-negative bacteria in a tertiary hospital, Nepal

Infections caused by beta-lactamases producing Gram-negative bacteria are increasing, thus posing a challenge to the management of such infections. The surveillance data of such bacteria is limited in Nepal so this study aimed to detect the beta-lactamase producing Gram-negative bacteria in a tertiary setting. A total of 604 clinical samples, including urine, blood, sputum and body fluids, were cultured and identified by the routine standard laboratory protocols. Antibiotic susceptibility testing was done by Kirby Bauer disc diffusion method following Clinical and Laboratory Standard Institute guidelines (2014). Extended-spectrum beta-lactamases (ESBL) producers were identified by combined disk method and metallo-beta-lactamases (MBL) producers were identified by Imipenem- EDTA combined disk method. Out of 604 samples, 282 (46.7%) samples showed significant growth, of which 229 (81.2%) were Gram-negative bacteria. Of 229 Gram-negative bacteria, 200 (87.3%) were multidrug resistant, 67 (29.3%) were ESBL producers and 16 (7.0%) were MBL producers. Klebsiella pneumoniae were among higher ESBL producers and Pseudomonas aeruginosa were among higher MBL producers. The findings suggest higher antibacterial resistance among Gram-negative bacteria with the added burden of beta-lactamase production. Imipenem was effective against 125 of 229 Gram-negative bacteria tested. Thus, imipenem can be the drug of choice for empirical management. The higher multidrug resistance and higher beta-lactamases production among Gram-negative bacteria warrant the continuous monitoring, surveillance, early detection, and infection control practices of such bacteria

Detection of metallo beta lactamase production in imipenem resistant gram negative bacilli non fermenters isolated in a Tertiary Care Hospital.

Objectives: Metallo-beta lactamase (MBL) producing non fermenter Gram negative bacilli is an emerging warning and cause of worry as they have established as one of the most feared resistance mechanisms and are the foremost cause of nosocomial infections worldwide. Carbapenem, including Imipenem, Meropenem and Doripenem are often used as a last remedy for treatment of infections caused by Pseudomonas aeruginosa, Acinetobacter and other Gram-negative. The present study was designed to explore the distribution of imipenem resistant non-fermenter Gram-negative bacilli isolates in different age groups. Study Design: Cross sectional Descriptive study. Setting: Microbiology laboratory, PGMI, Lahore. Period: January 2015 to December 2015. Material &amp; Methods: 53 imipenem resistant NFGNB that were isolated from appropriate sampling of patients suffering from several infections were analyzed by using different standard microbiological techniques like microscopy, culture methods, biochemical reactions and antibiotic susceptibility using Kirby-Bauer method. MBL recognition was performed by imipenem-2MPA double disc synergy test (DDST). Results: This study shows the frequency of imipenem resistant non-fermenter Gram-negative bacilli isolated from various clinical wards. Maximum NFGNB were recovered from surgery/surgical allied 35.84% followed by ICU 28.3%, medicine /medicine allied 20.75%, pediatrics 9.4% and gynae/obs 5.6% respectively. MBL production was identified among different imipenem resistant non-fermenter Gram-negative bacilli isolates by DDST using 2-MPA. Out of total 53 imipenem resistant non-fermenter Gram Negative Bacilli 37 Pseudomonas aeruginosa 20(54.05%) were MBL positive. Out of 13 Acinetobacter baumannii and 2 Pseudomonas luteola, 11(84.61%) Acinetobacter baumannii and 1(50%) Pseudomonas luteola were positive for MBL production. None of the Acinetobacter junii indicated MBL production. Conclusion: Double disc synergy test is operational for detection of MBL producers among NFGNB. It can be established in our routine clinical microbiology laboratories, for the MBL recognition especially in imipenem resistant isolates as of its cost efficiency.

Whole-genome analysis of New Delhi Metallo-Beta-Lactamase-1-producing Acinetobacter haemolyticus from China.

Infections caused by multidrug-resistant Acinetobacter spp. have generated worldwide attention. With the increasing isolation of non-baumannii Acinetobacter, the nature of associated infection and resistance needs to be explored. This study aimed to analyse the characteristics of New Delhi Metallo-Beta-Lactamase-1 (NDM-1)-producing Acinetobacter haemolyticus (named sz1652) isolated from Shenzhen city, China. The antibiotic spectrum was analysed after antimicrobial susceptibility testing. Combined disk test (CDT) was used to detect the metallo-beta-lactamases (MBLs). Transferability of carbapenem resistance was tested by filter mating experiments and plasmid transformation assays. Whole-genome sequencing (WGS) was performed using HiSeq 2000 and PacBio RS system. The Acinetobacter haemolyticus strain sz1652 was resistant to carbapenems and other tested agents except for amikacin, tigecycline and colistin. Production of MBLs was confirmed by CDT. Transfer of carbapenem resistance was unsuccessful. WGS analysis showed that the genome of sz1652 comprised a chromosome and two plasmids; 16 genomic islands (GIs) were predicted. Genes associated with resistance were found in this strain, including the beta-lactamase genes blaNDM-1, blaOXA-214 and blaLRA-18, the fluoroquinolone resistant-related mutations [GyrA subunits (Ser81Ile) and ParC subunits (Ser84Tyr)], and efflux pump genes related to tetracycline and macrolide resistance. Analysis of the genetic environment showed that blaNDM-1 was embedded in Tn125 transposon. The Tn125 structure was chromosomally located and shared > 99% sequence identity with the previously reported blaNDM-1 carrying region. The NDM-1-producing Acinetobacter haemolyticus coexisted with multiple drug-resistant determinants. The acquisition of the blaNDM-1 gene was probably facilitated by Tn125 in this strain. Non-Acinetobacter baumannii species also contained GIs.

High prevalence of imipenem-resistant and metallo-beta-lactamase-producing Pseudomonas aeruginosa in the Burns Hospital in Tunisia: detection of a novel class 1 integron

Pseudomonas aeruginosa is one of the most important causes of nosocomial infections, and its eradication is very difficult due to its multidrug resistance. The objective of the present study was to characterize the metallo-beta-lactamases (MBLs), integrons, OprD modifications and virulence factors of P. aeruginosa strains isolated from burn patients and to analyze their genetic relatedness by pulsed-field gel electrophoresis (PFGE) and multilocus sequence typing (MLST). Sixty-seven P. aeruginosa isolates were recovered from different clinical samples of burn patients hospitalized in the Intensive Care Burn Unit of the Centre de Traumatologie et des Grands Brulés (Ben Arous, Tunisia), and MBLs and alterations in porin OprD were analyzed among imipenem-resistant isolates. Class 1 and 2 integrons were studied by PCR and sequencing of corresponding variable regions. The presence of eight genes involved in the virulence of P. aeruginosa was investigated by PCR. Fourteen of the 36 imipenem-resistant P. aeruginosa (IRPA) isolates (38.8%) were MBLs producers and harbored the blaVIM-2 gene, in all cases included into class 1 integrons. A new class 1 integron was identified (intI1-blaOXA-10-aadB-blaVIM-2-aadB-blaOXA-10). Five sequence types were detected among IRPA isolates: ST1, ST112, ST238, ST308 and ST395. P. aeruginosa is a major nosocomial pathogen in patients suffering burns, and the spreading of multidrugs resistant and MBL-producing isolates should be controlled in burn units. Moreover, the implantation of infection control guidelines is crucial to decrease the morbidity and mortality of nosocomial infections due to multidrug resistant P. aeruginosa.

Burden of multidrug resistant respiratory pathogens in intensive care units of tertiary care hospital

Background: Lower respiratory tract infections are one of the most common infections among the patients in Intensive Care Units (ICUs). Admission in ICUs and use of life supporting devices increase the risk of infection with multidrug resistant pathogens.&#x0D; Aims and Objectives: This study was aimed to determine the prevalence and antibiograms ofthe bacterial pathogens causing lower respiratory tract infectionsamong patients of ICUs.&#x0D; Materials and Methods: A total of 184 specimens from patients admitted in ICUswith lower respiratory tract infections were included in this study. Isolation, identification and antibiotic susceptibility testing of the isolates was performed by standard microbiological techniques. Carbapenamase detection was performed by modified Hodge test method.Detection of metallo beta lactamase (MBL) was tested by imipenem and imipenem/EDTA disc. Detection of Klebsiellapneumoniaecarbapenamase (KPC) was performed by imipenem and imipenem/phenyl boronic acid.&#x0D; Results: Out of 184 samples, 131 showed significant growth of bacterial pathogens. Acinetobacter species (42.6%), Staphylococcus aureus (16.9%) and Pseudomonasaeruginosa(13.9%)were the three most common isolates. Out of 22 imipenem resistant isolates of Acientobacter species, 9 were KPC producer, 4 were MBL producers and 3 isolates were positive for MBL and KPC both. Among the Acinetobacter species, 5.1% isolates were resistant to tigecycline and colistin. One isolate of Pseudomonas aeruginosa was positive for MBL.&#x0D; Conclusions:High prevalence of multidrug resistant bacteria in ICUs was recorded. Gram negative bacilli were predominantly associated with LRTI among ICU patients;Acinetobacterspecies being most common isolate. Detection of carbapenamase among the Acinetobacterand emergence of tigecycline resistancelimits the therapeutic options.Regular monitoring of such resistant isolates would be important for managing infection control in critical units.

Beta‐lactamase‐producing Escherichia coli in Bangladesh: Their phenotypic and molecular characteristics

The emergence and rapid dissemination of beta-lactamase-producing E. coli is now a worldwide problem. A total of 45 E. coli obtained from clinical specimens from a medical service centre in Dhaka were selected for this study. Test E. coli exhibited variable resistance to 3rd (71.7 - 97.8%, n = 48) and 4th (78%, n = 48) generation beta-lactam antibiotics, with 72% sensitivity to Carbapenem. Analysis of co-resistance indicated that 33.3% of E. coli (n = 48) were co-resistant to beta-lactams and ciprofloxacin. ESBL producers were predominant comprising of 84.7% E. coli. Among them, 22.7% contained blaTEM, 24.2% contained blaCTX-M, 4.3% contained blaSHV and 9.1% contained blaOXA-1 genes. A total of 25.75% isolates were metallo beta-lactamase producers. Of these, 1.5% of E. coli strains contained New Delhi metallo beta-lactamase gene and 6% contained AmpC gene. Multiple beta-lactamase genes were detected in some test isolates; 6.7% isolates contained 4, 20% contained 3 and 73.3% contained 2 beta lactamase genes. Fifty per cent of the E. coli contained plasmids of variable sizes. In addition, a total of 39% of the E. coli contained Class 1 integron. The increasing trend in beta-lactam resistance is of public health concern as it limits treatment regime and indicates to the need of continuous monitoring of resistance pattern.&#x0D; Dhaka Univ. J. Biol. Sci. 28(1): 71-81, 2019 (January)

Evaluation of various risk factors associated with multidrug-resistant organisms isolated from diabetic foot ulcer patients.

AIMS:Diabetic foot ulcer is a dreaded complication of diabetes. Diabetic foot ulcer patients are often infected with multidrug resistant organism (MDRO) due to chronic course of the wound, inappropriate antibiotics treatment, frequent hospital admission, neuropathy, nephropathy, and peripheral vascular disease.MATERIALS AND METHODS:This prospective study was conducted in our 750 bedded hospital for a period of 6 months. The present study was undertaken to isolate various MDRO methicillin resistant Staphylococcus aureus; Gram-negative bacteria producing enzymes such as extended spectrum beta-lactamases (ESBL), Amp C, Carbapenamases; Pseudomonas and Acinetobacter species producing metallo-beta-lactamases (MBL). In addition we attempted to identify risk factors for association of diabetic foot ulcer and MDRO.RESULTS:A total of 149 bacterial isolates were identified. Of the total isolates 73.2% were Gram-negative and remaining 26.8% were Gram-positive bacteria. Among Enterobacteriaceae 59% were ESBL producers and 48% were Amp C producers. In addition, 41.5% of the isolates produced both ESBL and Amp C and 13.4% were carbapenem resistant Enterobacteriaceae. Among 20 Pseudomonas and Acinetobacter isolates, 5 were MBL producers (25%). Furthermore, in the study, 56% of patients with diabetic foot ulcer harbored MDRO. The risk of multidrug-resistant infection is significantly more in patients having diabetes duration >20 years and size of ulcer more than 4 cm2.CONCLUSION:The detection of MDRO in patients of diabetic foot ulcer changes the treatment strategies limits the antimicrobial options and causes higher complications among them.

Phenotypic detection of Metallo Beta Lactamase Producing Pseudomonas aeruginosa among Clinical Isolates from the intensive care unit of a tertiary care centre

Background: Pseudomonas aeruginosa is an opportunistic pathogenic bacterium responsible for both, acute and chronic infection, causing serious infections in patients who are mechanically ventilated individuals, who are immunocompromised, and patients with malignancies or HIV infection. Objectives: The phenotypic screening of metallo beta-lactamases (MBL) in strains of Pseudomonas aeruginosa resistant to imipenem. Material and Methods: The study was carried out in the department of Microbiology, in a medical hospital, Bareilly, over a period 18 months from January 2013 to June 2014. A total of 103 Pseudomonas aeruginosa isolated from sputum, broncho alveolar lavage (BAL), urine, pus and blood from critically ill patients admitted in the intensive care unit of a tertiary care centre. Strain of P. aeruginosa resistant to imipenem, were tested for metallo beta-lactamase production by phenotypic methods. Result: Out of 103 Pseudomonas aeruginosa, 48 strains were found imipenem resistant, of which 43(89.6%) were MBL positive by imipenem -EDTA combined disc test and the rest 35(72.9%) were by modified Hodge test. Conclusion: Imipenem – EDTA combined disc test found to be the best phenotypic method for detection of MBL. The appearance of the MBL and their spread among bacterial pathogens is a matter of concern with regard to the future of antimicrobial therapy. Both the methods are simple and one of these phenotypic methods can be easily incorporated in routine lab procedures to detect MBL.

The Frequency of VIM 2, 3, 9, 11 and VIM all among Metallo-beta-Lactamase Producing Pseudomonas aeruginosa

Introduction: Antibiotic resistance crisis has always been a serious problem for human health and many hospitalized patients are affected worldwide. Pseudomonas aeruginosa is a gram-negative pathogen and one of the most common causes of nosocomial infections. The main mechanism of resistance to beta-lactam antibiotics is the presence of metallo-beta-lactamase (MBL) enzymes. Most of the MBL genes are found in plasmids. The aim of this study was to evaluate the frequency of MBL-producing P. aeruginosa isolates caused by VIM-all and VIM 2, 3, 9, 11and16 genes. Materials & Methods: Antimicrobial susceptibility of 127 clinical isolates of P. aeruginosa was determined using the standard Kirby-Bauer disk diffusion method according to Clinical and Laboratory Standard Institute (CLSI). Combined-disk test was used for phenotypic determination of MBLs-producing isolates. After DNA extraction, VIM-all and in specific, VIM 2, 3, 9, 11 and 16 genes were amplified using PCR method. Findings: A total Of 127 clinical isolates of P. aeruginosa, 62 isolates (49%) were resistant to imipenem and 31 isolates (24.5%) showed phenotypic evidences of MBL production. Moreover, among imipenem resistant strains VIM-all genes were found in 12.5% of cases, but the VIM 2-3-9-11 and 16 genes were not detected in samples. Discussion & Conclusions: The results obtained in this study suggest that in P. aeruginosa, the highest antibiotic resistance observed was to cefazolin (98%) followed by nalidixic acid (91%) and the least resistance were to ciprofloxacin (31%). One of the reasons for this trend is the growth of antibiotic-resistant bacteria and the known mechanisms of bacterial resistance.

Prevalence of Extended Spectrum Betalactamase (ESBL) and Metallobetalactamase (MBL) Producing Pseudomonas aeruginosa and Acinetobacter baumannii Isolated from Various Clinical Samples.

This study was conducted with an objective to find the prevalence of extended spectrum betalactamase (ESBL) and metallobetalactamase (MBL) in P. aeruginosa and A. baumannii isolates obtained from various clinical samples. It was conducted in the Department of Microbiology, Adesh Institute of Medical Sciences and Research, Bathinda, over a period of two years from July 2014 to June 2016. Clinical specimens including urine, pus, blood, high vaginal swabs, respiratory samples, and various body fluids were processed and P. aeruginosa and A. baumannii isolates were identified by standard protocols. Antibiotic sensitivity testing for all isolates was done using Kirby-Bauer disc diffusion method. Disc potentiation test was performed to check ESBL and MBL production in these bacteria. Maximum ESBL positive isolates of P. aeruginosa were observed among pus samples and maximum MBL positive isolates were detected in tracheal aspirates. A. baumannii showed maximum positivity for ESBL and MBL production in endotracheal secretions. This study gives an alarming sign towards high prevalence of cephalosporin and carbapenem resistance due to production of extended spectrum betalactamases and metallobetalactamases, respectively. Early detection, stringent antibiotic policies, and compliance towards infection control practices are the best defenses against these organisms.

Extended Spectrum Beta Lactamase and Metallo Beta Lactamase producing Pseudomonas aeruginosa at Tertiary care Hospital of Nepal

Objective: To assess the prevalence of Extended spectrum beta lactamase (ESBL) and Metallo beta lactamase (MBL) producing Pseudomonas aeruginosa from pus samples.&#x0D; Methods: A cross-sectional study was conducted at Kanti Children’s Hospital, Kathmandu, Nepal during which 316 pus samples were collected and tested using standard microbiological procedures. Antibiotic Susceptibility Test (AST) was done by Kirby-Bauer disk diffusion method and the detection of ESBL and MBL production were done using Ceftazidime/clavulanic acid combined disk test and Imipenem- Ethylenenediaminetetraacetic acid combined disk test respectively as per CLSI guideline 2014.&#x0D; Results: The prevalence rate of P. aeruginosa was found to be 7.9% in pus samples. Out of 25 P. aeruginosa isolates 9(36%) were ESBL producers and 2(8%) were MBL producers. ESBL producers were predominant in the age group 2-3 years (33.3%) and in male patient (55.6%). Out of 2 MBL producing P. aeruginosa, 1(50%)was isolated from the age group below 2 years and male patient and 1(50%) from the age group 8-9 years and female patient. 96% of isolates showed sensitive to Polymyxin B.&#x0D; Conclusion: The study showed increasing trend of ESBL and MBL production in P. aeruginosa so constant survey of prevalence of ESBL and MBL producing isolates is essential to control and manage spread of these isolates in different units of health institutions.

Antibiotic Resistance in Clinical Isolates of Pseudomonas aeruginosa: A New Viewpoint for Antibiotic Prescription

Background: A growing number of resistant Pseudomonas aeruginosa isolates have been reported. To make better choice of antibiotic, reporting and analyzing the recent antibiotic resistance patterns of the bacterium are of crucial importance. The purpose of the present study was to survey antibiotic resistance status in clinical isolates of P. aeruginosa and to make more options for antibiotic prescription by revisiting antibiogram results. Methods: A total of 138 molecularly identified P. aeruginosa strains isolated from clinical specimens were tested for sensitivity to 10 antibiotics using Kirby-Bauer disk diffusion method. In addition, phenotypic combined disk diffusion test (CDDT) was applied to screen metallo-beta-lactamase (MBL) producing P. aeruginosa isolates among imipenem-resistant isolates. To find the most suitable antibiotic against P. aeruginosa infections, a new analytical way was employed using SPSS and chi-square test. Results: Ceftizoxime showed the highest rate of resistance (78.9%) and amikacin showed the lowest (33.3%). 51.4% of the isolates showed resistance to Imipenem, 78.8% of which were positive for MBL production. Multidrug-resistant strain (MDR) isolates were observed in 67.3% of all isolates, 74.6% of Imipenem resistant isolates showed multidrug resistance and 83.9% of MBL positive isolates showed MDR. There was positive correlation between specimen source and resistance or susceptibly of P. aeruginosa isolates to some antibiotics in some specimens, and non-significant similarities in resistance or sensitivity to antibiotics in P. aeruginosa isolates (P<0.05). Conclusions: Resistance rate of imipenem, meropenem, gentamicin, tobramycin, ceftazidim, cefotaxime and ticarcillin was more than reported rates in previous studies. A higher proportion of MDR isolates and MDR-MBL producing strains suggest drastic dissemination of resistant isolates in the healthcare centers. Site specificity and non-significant similarity of the responses to antibiotics in P. aeruginosa isolates can provide a new sight for antibiotic prescription and better control of antimicrobial drug resistance.

High incidence of MBL-mediated imipenem resistance among Pseudomonas aeruginosa from surgical site infections in Egypt.

Surgical wound infection is a serious problem, especially with metallo-beta lactamases (MBLs)- producing gram-negative bacteria as Pseudomonas aeruginosa. The main objective of this work was to evaluate for the first time in Minia- Upper Egypt, the incidence of imipenem-resistant Pseudomonas aeruginosa infection of surgical wounds particularly that mediated by MBL production. P. aeruginosa was isolated from infected wounds by swabs and underwent full microbiological identification and Antibiotic Susceptibility testing. MBL production was tested by E-test and PCR was used for imipenemase (blaIMP) and Verona integron-encoded metallo-beta-lactamase (blaVIM) gene detection. Out of 200 pus samples collected from surgical site infections, P. aeruginosa had the prevalence rate of 35%. Imipenem resistance was found in 28.57% of the isolated Pseudomonas aeruginosa. The prevalence of MBL-producing isolates among Imipenem-resistant P. aeruginosa (IRPA) was 85 % by phenotypic method with 29% of them harboring blaVIM gene. High resistance rates to other classes of antibiotics were reported among the isolates with multi-drug resistance (MDR) detected in 97.3% of the isolates. To our knowledge, this is the first report in Minia, Upper Egypt describing the relatively high incidence of IRPA in infected surgical wounds with MBLs involved in the majority of isolates.

The emergence of blaOXA-48 and blaNDM among ESBL-producing Klebsiella pneumoniae in clinical isolates of a tertiary hospital in Iran.

The aim of this study was to investigate the prevalence of carbapenem-resistant Klebsiella pneumoniae (CRKP) and the most common types of carbapenemases, metallo-beta-lactamases (MBLs), and extended-spectrum beta-lactamases (ESBLs) among CRKP isolates in a tertiary hospital in Isfahan, Iran. Eighty non-repetitive clinical isolates of K. pneumoniae were obtained from different clinical specimens. Antibiotic resistance pattern of isolates was determined by disk diffusion method and production of carbapenemases and MBLs was confirmed using modified Hodge test and E-test, respectively. Molecular detection of the antibiotic resistance genes was performed using PCR. Fifty-one (63.8%) isolates have decreased susceptibility to carbapenems, of which 46 (90.2%) isolates were as carbapenemase producer and four (7.8%) isolates were positive for MBLs, phenotypically. The results of PCR showed that the prevalence of blaOXA-48, blaNDM, blaSHV, blaCTX-M, and blaTEM genes among CRKP isolates were 90.2%, 15.7%, 98%, 96.1%, and 90.2%, respectively. No isolates carrying the blaKPC, blaGES, blaIMI, blaVIM, and blaIMP genes were detected. This study showed that the production of OXA-48 is one of the main mechanisms of resistance to carbapenems in CRKP isolates in Isfahan. In addition, the dissemination of NDM-producing CRKP isolates is a potential risk for the health care system of this area in the near future.

Phenotypic Detection of Β-Lactam Antibiotics, Methicillin and Inducible Clindamycin Resistance Among Bacterial Isolates in Patients with Otitis Externa

Background: Otitis is a general terminology used for inflammation or infection of the ear; Staphylococcus aureus and Pseudomonas spp. are the most common causes of otitis externa. The resistance mechanism against the beta-lactams group is due to the production of β-lactamase enzymes by the bacteria; the enzymes in staphylococci are encoded by erm genes that confer inducible Clindamycin resistance. Objectives: This study aimed at investigating bacterial resistance by evaluating samples collected from Otitis Externa patients admitted to Ayatollah Roohani Hospital of Babol, Iran. Methods: Ear samples were collected from 72 patients with Otitis Externa referred to Ayatollah Roohani hospital during May 2012 to 2013. At first, the isolated bacteria were identified using appropriate differential and selective media, and then were tested for antimicrobial susceptibility testing following the disk diffusion method. Special diagnostic tests were also performed for the identification of ESBL, iAmpC, pAmpC, metallo beta lactamase producers and inducible resistance to clindamycin and methicillin resistant strains. Data were analyzed by the SPSS 22 statistical software. Results: Among the 65 isolated bacteria, 24 (36.9%) cases were found to be gram negative and 41 (63.1%) were gram positive; pAmpC beta-lactamase producers were found to have the highest frequency in gram negative bacteria. From 36 (87.8%) isolated CoNS, 18 (50%) bacteria were found to be resistant to the methicillin group and 4 (11.1%) cases had inducible resistance to clindamycin; All isolated S. aureus were sensitive to methicillin and clindamycin. Conclusions: Considering that some bacteria are concurrently able to produce different types of resistance enzymes, and also the fact that high prevalence rate of resistance belongs to CoNS, it is important and necessary to perform antimicrobial susceptibility testing as per clinical and laboratory standards institute (CLSI) methods in clinical laboratories.

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 Analysis of Pseudomonas aeruginosa Metallo-Beta-Lactamase: A First Report of an Iranian Referral Pediatric Hospital.

Pseudomonas aerouginosa is an important opportunistic pathogen which causes clinical infections among ill patients. Metallo- Beta- lactamases (MBLs) are important mechanisms of carbapenem (drug of choice) resistance among Pseudomonas aerouginosa isolates. The aim of this study was to determine B- lactamases genes (bla-genes) in P. aerouginosa isolates and to detect percentage of MBLs among P. aerouginosa isolates in different wards. Clinical isolates of P. aerouginosa in patients hospitalized at Children's Medical Center were collected in two years using a sterile swab. For differentiation and identification of strains the BHI media, Sytrymaid agar and Oxidase test were used and Kirby Baure method antibiotic susceptibility and PCR assay were performed for detection of bla-genes. Based on the study results from a total of 269 isolates of P. aerouginosa, 39 isolates were found to be imipenem resistant. From these isolates, 19 strains of P. aerouginosa isolates were determined to be MBL producers by phenotypic method. All of the Imipenem resistant P. aerouginosa isolates were examined by PCR for the presence of the bla-genes. All MBL- producing isolates carried bla-IMP Genes. And the results of the antibiogram showed the greatest resistance to the Nitrofurantoin, Nalidixic acid and Cotrimoxazole and Cefixime (100%) and resistance to other antibiotics was also significant. Considering the prevalence and clinical importance of MBL producing isolates, rapid identification of them and use of the appropriate infection control measures are necessary to prevent further spread of them by these organisms and to help treatment of Infections.