Background: Early detection of extended-spectrum β,-lactamases (ESBLs) producing bacteria is critical for infection prevention and control. Numerous phenotypic approaches and automated systems have been developed for detecting ESBL bacteria. However, there is a scarcity of data in Ethiopia regarding the most reliable, simple, and cost-effective methods for detecting ESBL-producing bacteria. This study, therefore, aimed to evaluate the diagnostic performance of three phenotypic approaches for detecting ESBL-producing bacteria. Methods: In this study, 117 isolates of Klebsiella pneumoniae, Escherichia coli, Klebsiella oxytoca, and Proteus mirabilis were examined. Cefotaxime (30 μ, g) and ceftazidime (30 μ, g) were used for screening ESBL enzymes. A screening breakpoints of ≤,27 mm and ≤,22 mm were used for cefotaxime (30 μ, g) and ceftazidime (30 μ, g), respectively, as per the Clinical and Laboratory Standards Institute (CLSI) guidelines. All 117 strains were further confirmed by the Vitek 2 compact, Double disk synergy, ESBL Epsilometer test, and combined disk method. The combined disk method was adopted as the reference method. Results: Out of 117 isolates, 90 (86%) had zone diameters of ≤,27 mm and ≤,22 mm for cefotaxime (30 μ, g) and ceftazidime (30 μ, g), respectively. The reference method detected 76 (65%) ESBL isolates out of 117 ones. From among the three techniques (i. e., Double disk synergy, Vitek 2 compact, and ESBL Epsilometer test), the Double disk synergy method demonstrated overall sensitivity and specificity of 97. 4% and 97. 6%, respectively. Vitek-2, cefotaxime, and ceftazidime Epsilometer test indicated indeterminate results of 6. 8%, 6. 8%, and 5. 1% respectively. Conclusion: Double disk synergy was found to have the highest sensitivity and specificity for detecting ESBL isolates with no indeterminate results.

Background and Objectives: Salmonella infections are endemic in many developing countries with poor sanitary conditions, but emerge sporadically as a serious public health threat in developed countries. Infections with multidrug resistant (MDR) strains of Salmonella have been associated with treatment failures. Salmonella spp. resistant to extended spectrum cephalosporins are increasing in prevalence worldwide. The aim of this study was to determine the antimicrobial susceptibility, multidrug resistance and extended spectrum beta lactamase (ESBL) production among clinical isolates of Salmonella spp. during 2007 in Tehran, Iran.Patients and Methods: In this cross-sectional study, fifty Salmonella spp. were identified by API 20E system and serotyped by the slide agglutination test. disk diffusion test was performed. Double disk synergy test was used as a screening test for ESBL production, using disks of cefotaxime and ceftazidime with and without clavulanic acid.Results: From 50 Salmonella spp. 12 (24%) were S. enterica serogroup paratyphi B, 24 (48%) S. enterica serogroup paratyphi C and 14 (28%) were S. enterica serogroup Typhi. The most susceptibility and resistance were observed to ceftazidime (98%) and amoxicillin-clavulanic acid (96%), respectively. 28(56%) were resistant to 5 or more antibiotics. ESBL production was detected by Double disk synergy test in one isolate (2%).Conclusion: Results showed increase in antibiotic and multidrug resistance pattern of Salmonella spp. comparing to previous studies in Iran and other countries. It seems that this is the first report of Salmonella spp. ESBL producing in Iran.

Background and Objectives: Since the fluoroquinolones are the broad-spectrum antibiotics, they affect both Gram-negative and Gram-positive bacteria. These antibiotics are widely prescribed by physicians. As a result, some bacteria, especially Enterobacteriaceae, have shown a resistance to this family of antibiotics. The current study aimed at detecting the frequency of qnrA, qnrB, and qnrS genes, novel plasmid-mediated quinolone-resistance genes, among extended-spectrum β-lactamases (ESBL)-positive and ESBL-negative Klebsiella pneumoniae isolates. Materials and Methods: One hundred and thirty isolates of K. pneumoniae were collected from Imam Reza Hospital and its associated clinics from May 2011 to July 2012. The isolates were tested for ESBLs by the conventional methods. Polymerase chain reaction (PCR) was performed to amplify qnr A, B, and S. Results: Thirty-eight (29. 3%) isolates were ciprofloxacin-resistant. Among 130 K. pneumoniae infectious isolates, 56 (43%) were capable of producing ESBL; 10. 8% (n=14), 15. 4% (n=20), and 20. 8% (n=27) of ESBL-producing K. pneumonia were positive for qnrA, qnrS, and qnrB, respectively, and 13. 8% (n=18) of the isolates harbored 2 or 3 qnr genes. Conclusion: The results of the current study showed that quinolone-resistance genes were more frequent in ESBL-producing K. pneumoniae (37. 5%) isolates, compared with the ESBL-negative isolates (20. 89%). The prevalence of qnr genes was high in K. pneumoniae isolates, with higher frequency in ESBL-positive strains. Most of the isolates were positive for all 3 groups of qnr genes and the qnrB was the most common one.

Objective(s): The aim of this study was to investigate the presence of PER-1-type ESBLs in drug resistantPseudomonas aeruginosaisolates.Materials and Methods: During one-year period (2008-2009), following isolation and identification of 56P. aeruginosa, the E -test method was performed for determination of minimal inhibitory concentration of ceftazidim. The isolates that they had MIC ³16 mg/ml against ceftazidim were used for determination of ESBL-producing by combined disk test (CDT) and Double disk synergy test (DDST) methods.Bla PER-1 gene was investigated by PCR.P. aeruginosaKOAS was used as positive control.Results: Twenty-nine (51.78%) out of fifty six isolates had MIC³16 mg/ml to ceftazidime, twenty two (75.86%) of them were ESBL producers. Some isolates (27.5%) containedbla PER-1 gene.Conclusion: PER-1-type ESBLs producingP.aeruginosa has not been reported previously in Tabriz but there has been a rather high prevalence of it.

Background and Aim: Pseudomonas aeruginosa is one of the opportunistic pathogen that causes nosocomial infections in hospitals. It involves in burn wound, respiratory, people with genetic disease cystic fibrosis, bacterimia, septicemia and other infections. Pseudomonas aeruginosa by producing metallo-b-lactamase, can hydrolyze most of b-lactam antibiotics, showing resistance to various antimicrobial agents. Thus, according to numerous reports of existence of this resistance in Pseudomonas aeruginosa, the purpose of this study was to detect the strains of Pseudomonas aeruginosa that are resistant to metallo-b- lactamase.Material and Methods: 47 strains of Pseudomonas aeruginosa isolated from patients admitted to Shohadaye Ashayer hospital, Khorramabad. Then isolates were identified with routine tests. Antibiotic susceptibility test was done by disk-Diffusion method. All isolates were screened for metallo-b-lactamase production by Double disk synergy test (DDST).Results: In this study, 51.7, 6.8, 58.6, 65.5, 51.06 and 51.7% of the strains were resistant to ceftazidime, cefotaxime, gentamicin, ciprofloxacin, imipenem and meropenem, respectively. Out of the 47 Pseudomonas aeruginosa isolates 24 (51.06%) strains were resistant to imipenem. Among which 19 strains were positive for metallo-b-lactamase by DDST method.Conclusion: High prevalence of metallo-b-lactamase producing strains showed that testing to detect metallo-b-lactamase production is essential along with antibiotic susceptibility testing in health centers.

Background: Pseudomonas aeruginosa is one of the most common Gram negative bacteria involved in nosocomial infections. Presence of Extended-spectrum Beta-lactamases (ESBLs) genes, play an important role in induction of resistance in beta-lactamase producing species to beta lactam antibiotics. Frequency of resistance to these antibiotics is increasing. In this study, antibiotic sensitivity and frequency of ESBLs in Pseudomonas aeruginosa which had been isolated from clinical specimens, was assessed by phenotypic methods.Methods: This study was performed on 200 isolated Pseudomonas aeruginosa from clinical specimens in Imam Khomeini and Imam Reza hospitals, Kermanshah during 2013. Specimens were determined and cultured by standard conventional methods. Antibiotic sensitivity test on 14 antibacterial agents was performed according to CLSI criteria. Then, frequency of ESBLs producing isolates was determined by Combined disk Test (CDT) and Double disk synergy Test (DDST) methods.Results: This study revealed that the highest and lowest resistance rate were against to cefpodoxime (100%) and piperacilin-tazobactam (34%), respectively. Using CDT and DDST methods, 41% of isolates were ESBL positive.Conclusion: Considering high resistance rate of Pseudomonas aeruginosa to majority of antibiotics and increasing frequency of ESBLs producing isolates, we need for infection control criteria and use of appropriate therapeutic protocols according to antibiogram test patterns.

Background: New Delhi metallo-beta-lactamase-1 (NDM-1) is one of the most important emerging antibiotic resistance. Co-harboring three or four carbapenemases is rare and only a few reports exist in the literature. We described the characteristics of the large epidemic outbreaks and reports co-producing blaNDM-1 with the other carbapenemase genes in P. aeruginosa isolates. Methods: This present cross-sectional research was conducted on 369 P. aeruginosa isolates obtained from burn and general hospitals within years 2013 to 2016. Beta-lactamase classes A, B and D genes were identified by PCR method. Modified hodge test (MHT), Double-disk potentiation tests (DDPT) and Double disk synergy test (DDST) were performed for detection carbapenemase and metallo beta-lactamase (MBL) production of blaNDM-1 positive P. aeruginos isolates. Results: From 236 carbapenem-resistant P. aeruginosa (CRPA), 116 isolates have had MBL genes and twentynine isolates were found positive for blaNDM-1. In CRPA isolates, blaIMP-1, blaVIM-2 and blaOXA-10 were identified in 27. 5%, 21. 1% and 32. 2% of isolates respectively, while co-producing blaNDM-1, blaIMP-1, blaOXA-10, co-producing blaNDM-1, blaVIM-2, blaOXA-10 and co-producing blaIMP-1, blaVIM-2 were determined in 11 (4. 6%), 8 (3. 4%) and 27 (11. 4%) of isolates respectively. Conclusion: The finding of this co-existence of multiple carbapenemase resistance genes is threating for public health. Dipicolinic acid is a superior MBL inhibitor in DDPT antique than EDTA in DDST method for the detection of MBL-blaNDM-1 producing P. aeruginosa.

Pseudomonas aeruginosa is an opportunistic pathogen which is naturally resistant to a large range of antibiotics like lots of Beta–Lactams (penicillins, cephalosporins and carbapenems) and may cause additional resistance after unsuccessful treatment. The understanding of beta-lactamase identification and detection in these bacteria is very valuable. In recent years a number of variety of new beta-lactamases were detected, apparently as a consequence of the clinical use of novel classes of beta-lactam antibiotics.Thus a reliable test to detect extended spectrum beta-lactamases (ESBLs) in clinical isolates of P.aeruginosa is needed. In this study, a total of 100 clinical isolates of P. aeruginosa were studied to assess sensitivity of P.aeruginosa isolated from burned patients of Motahari Hospital in Tehran and determine ESBL production in them. Antibiogram test was done by disk diffusion method. Beta-lactamases producers were screened by Starch-paper strip method.Further confirmation was done for ESBL producers by Double disc test (DDT) and Double disc synergy test (DDST). Among the total of 100 isolates that were considered beta-lactamase producer by starch paper strip method, 17% were ESBL positive by DDST, a figure that increased to 70% after imipenem was included.In addition, 20% of isolated P.aeruginosa strains were ESBL positive by other confirmatory test. This study is the first that uses a combination of paper strip method with DDT and DDST.