Prevalence of class 1 integron among multidrug-resistant Acinetobacter baumannii in Tabriz, northwest of Iran.

Integrons are associated with a variety of gene cassettes, which confer resistance to multiple classes of antibacterial drugs. In this study we tested the frequency of class 1 and 2 integrons among multidrug-resistant Acinetobacter baumannii (MDRAB) clinical isolates. One hundred clinical isolates of A. baumannii were screened for carriage of class 1 and 2 integrons by PCR method. Results showed that seventy four (92.5%) of 80 MDRAB carried class 1 integron. Integron-positive isolates were statistically more resistant to aminoglycoside, quinolone and beta-lactam compounds except for cefepime. This is the first report of class 1 integrons in MDRAB isolates in northwest Iran.

Genotypic and phenotypic characterisation of clinical isolates of methicillin-resistant Staphylococcus aureus in two different geographical locations of Iran.

Background: Methicillin-resistant Staphylococcus aureus (MRSA) has become more prevalent all over the world and it is important to determine MRSA prevalence and typing in different regions. The present study was carried out to determine the prevalence and frequency of circulating molecular types of MRSA isolates as well as their antibiotics susceptibility in Tabriz and Kerman cities of Iran. Materials and Methods: A total of 230 S. aureus isolates were collected from Tabriz (n=125) and Kerman (n=105) during January to December 2018. MRSA isolates were identified by PCR amplification of nuc and mec A genes. Antibiotic susceptibility of MRSA isolates were determined by Kirby-Bauer disk diffusion method. Multiplex PCR was exploited to detect various types of SCCmec. Results: The MRSA prevalence was 51/125 (40.8%) in Tabriz and 60/105 (57.1%) in Kerman. Overall, 36/51 (70.58%) and 15/51 (29.41%) isolates and 37/60 (61.66%) and 23/60 (38.34%) isolates were isolated from inpatients and outpatients in Tabriz and Kerman, respectively. Almost all of the isolates were resistant to penicillin and all of them were sensitive to linezolid. Thirty five (68.2%) and 34(56.6%) of MRSA isolates in Tabriz and Kerman were determined as MDR, respectively. SCCmec typing showed that the frequent SCCmec type in both Tabriz and Kerman cities was SCCmec III (56.86% and 55%, respectively). Conclusion: The high prevalence of MRSA makes it necessary to revisit the antibiotics administration by physicians. Indeed, periodic evaluation of antibacterial susceptibility patterns of the MRSA strains is required for efficient treatment of MRSA infections.

Klebsiella pneumoniae in neonatal sepsis: a 3-year-study in the pediatric hospital of Tabriz, Iran.

Neonatal sepsis is a life-threatening emergency, and any delay in treatment may cause death. Because of the importance of the problem in Iran, the aim of this retrospective study was to determine the etiological agents of neonatal septicemia, and the prevalence and epidemiology of Klebsiella bacteremia in the neonatal wards. Two hundred and ten cases of neonatal sepsis occurred during the study period. The most common organism was coagulase-negative staphylococci. Gram-negative organisms were isolated in 66 cases (31.43%), and the most common Gram-negative organism causing neonatal sepsis was Klebsiella pneumoniae. The mortality rate due to Gram-negative bacteria including K. pneumoniae was higher than that due to other bacteria. The distribution of the main pathogens is different in the Azerbaijan state, northwest of Iran, and K. pneumoniae is predominant, but Streptococcus agalactiae plays a relatively minor role in the etiology of sepsis during the first month of life.

Analysis of cervical lesions for presence of HSV-2 and HPV-16 and HPV-18 in Iranian patients by PCR.

Objective Cervical cancer (CC) is one of the leading causes of deaths from cancer among women worldwide. Viral infections is now one of the known risk factors for CC. The aim of this study was to investigate the presence of herpes simplex virus type 2 (HSV-2), human papilloma virus types 16 (HPV-16) and human papilloma virus types 18 (HPV-18) in Iranian patients with CC using the polymerase chain reaction (PCR). Materials and methods This case-control study was conducted on a total of 45 patients with CC from Khatam-Al-Anbiya Hospital, Hamadan, Iran during 2014, and 30 samples from healthy subjects as controls. The presence of HSV-2 and HPV-16/18 DNA sequences was detected by PCR. Results Eight of CC patients (17.77%) had HPV-16/18 DNA and only one patient (2.22%) with HSV-2 was identified. These viruses were not detected in control cases. Among HPV-16/18 positive patients, 62.5% and 37.5% biopsies were positive for HPV-16 and HPV-18, respectively. On the other hand, only one case (2.22%) was positive for HPV-16/18, but HSV-2 and this co-infection was not detected in the control group. Conclusion Our results demonstrate that there was no direct molecular evidence to support a cofactor relationship between HSV-2 and HPV-16/18 in cervical malignancies. However, the results about HPV-16/18 was in accordance with previous studies.

Clinical test to detect mecA and antibiotic resistance in Staphylococcus aureus, based on novel biotechnological methods.

BACKGROUND AND OBJECTIVE: Methicillin-resistant Staphylococcus aureus (MRSA) is one of the most common organisms isolated from clinical samples, and has been associated with morbidity and mortality among hospitalized patients. The aim of this study was to evaluate the prevalence and antibiotic susceptibility patterns among MRSA and methicillin-sensitive S. aureus (MSSA) isolates collected from four hospitals in Iran. MATERIAL AND METHODS: A total of 183 isolates of S. aureus were collected from various clinical specimens of four hospitals in Iran. The isolates were identified by using the conventional biochemical tests. Three methods-oxacillin agar disk diffusion, oxacillin agar screening, and PCR- were applied to determine susceptibility to oxacillin. The conventional disk agar diffusion test was used to evaluate the antibiotic sensitivity of our isolates against 15 antibiotics, according to the guidelines of the Clinical and Laboratory Standards Institute (CLSI). RESULTS: Of 183 isolates, 77 isolates (42.1%) were found to be MRSA, by the PCR method. The highest antibiotic resistance was found to be against penicillin, co-trimoxazole, erythromycin, and tetracycline respectively. All isolates were susceptible to vancomycin, according to the results of disk agar diffusion. Among other antibiotics, teicoplanin (84%) and fusidic acid (80.5%) were more active against MRSA isolates. For the different methods evaluated, the sensitivities and specificities were as follows: for disk agar diffusion (84.9% and 95.9%) and for agar screening test with oxacillin concentrations of 0.6 µg/ml (70.8% and 97.4%), 4 µg/ml (96.1%and 97.2%) and 6 µg/ml (96% and 96.3%), respectively. CONCLUSION: The results of our study showed that 47% of S. aureus isolates were MRSA. Overall, in this research study, resistance to all test antimicrobial agents in MRSA isolates were higher than that of MSSA isolates. Our results also revealed that 85% of mecA-positive isolates and 15% of mecA-negative isolates were resistant to methicillin; while 96% of mecA-negative isolates were sensitive to methicillin. Meanwhile 4% of mecA-positive isolates were also sensitive to methicillin.

Emergence of colistin resistant Pseudomonas aeruginosa at Tabriz hospitals, Iran.

BACKGROUND AND OBJECTIVES: The prevalence of multidrug resistant Pseudomonas aeruginosa is the main reason of new drugs resurgence such as colistin. The main objectives of this study were to determine the antibiotic resistance pattern and the rate of colistin resistance along with its correlation with overexpression of MexAB-OprM and MexXY-OprM efflux pumps among P. aeruginosa isolates. MATERIALS AND METHODS: Hundred clinical isolates were collected from 100 patients during 6 months in 2014. Susceptibility to the eight antibiotics was investigated using Kirby-Bauer and agar dilution methods. The Quantitative Real-time PCR was used to determine the expression levels of efflux genes. RESULTS: Resistance rates to various antibiotics were as follows: ticarcillin (73%), ciprofloxacin (65%), aztreonam (60%), ceftazidime (55%), gentamicin (55%), imipenem (49%), piperacillin/tazobactam (34%) and colistin (2%). In disk diffusion method, only two isolates were non susceptible to colistin, however in agar dilution method the two isolates were confirmed as resistant and two others were intermediate resistant. Sixty eight (68%) isolates were multi-drug resistant and 10 isolates were susceptible to all tested antibiotics. Both colistin resistant isolates showed overexpression of both efflux pumps, but two intermediate resistant isolates exhibited reduction of efflux genes expression. CONCLUSIONS: Emergence of colistin resistance is increasing in P. aeruginosa indicating great challenge in the treatment of infections caused by MDR strains of this organism in Iran. ParRS may promote either induced or constitutive resistance to colistin through the activation of distinct mechanisms such as MDR efflux pumps, and LPS modification.

Contribution of mexAB-oprM and mexXY (-oprA) efflux operons in antibiotic resistance of clinical Pseudomonas aeruginosa isolates in Tabriz, Iran.

Overexpression of efflux pumps is one of the most important mechanisms that contributes to intrinsic and acquired resistance to antibiotics in Pseudomonas aeruginosa. The present study evaluated the role of MexAB-OprM and MexXY (-OprA) efflux pump overexpression in antibiotics resistance of P. aeruginosa clinical isolates. One-hundred clinical isolates of P. aeruginosa were obtained from four hospitals of Tabriz city in Northwest Iran. Isolates were identified and evaluated by the disk diffusion method and agar dilution in order to determine antibiotic resistance. Effect of Phenylalanine Arginine beta-Naphthylamide (PAßN) on susceptibility to various anti-Pseudomonas antimicrobials and expression levels of mexB and mexY using quantitative real-time PCR were determined in the clinical isolates. Random Amplified Polymorphic DNA Typing (RAPD-PCR) was used for genotyping of the isolates. The most and least effective antibiotics tested were colistin and ofloxacin, respectively. Seventy-one percent of the isolates were found as multidrug resistant (resistant to at least three different classes of antibiotics). Among ciprofloxacin and levofloxacin resistant isolates, 39.6% and 28.5% of them showed four-fold reduction in MIC with PAßN, respectively. Sixty-two percent and 65% of isolates overexpressed mexB and mexY, respectively. Sixty six isolates showed overexpression of both mexB and mexY efflux genes. Moreover, 76% and 88.7% of MDR isolates were mexB and mexY overexpressed, respectively. There were 30 different RAPD types in this study which were clustered into 6 clones. The study indicated that there is a significant correlation between the expression of efflux pumps and the resistance to most anti-pseudomonal antibiotics.

Detection of Methicillin-Resistant Coagulase-Negative Staphylococci and Surveillance of Antibacterial Resistance in a Multi-Center Study from Iran.

BACKGROUND: Coagulase-negative staphylococci (CNS) are a common cause of nosocomial infections. In recent years, an increase in the incidence of methicillin-resistant coagulase-negative staphylococci (MRCNS) has led to the severity of the disease. OBJECTIVES: The aim of this study was to isolate and identify MRCNS strains by oxacillin disk agar diffusion, oxacillin agar screening, and polymerase chain reaction (PCR) and to evaluate their antibacterial resistance patterns. PATIENTS AND METHODS: Totally, 122 CNS isolates were collected from the clinical specimens of four hospitals in Iran. Susceptibility testing was performed by disk agar diffusion against 15 antimicrobial agents. Then, disk agar diffusion, agar screening, and PCR were applied to determine susceptibility to oxacillin. RESULTS: Out of the 122 isolates, 92 isolates were found to be MRCNS by PCR. The sensitivities and specificities of disk agar diffusion and agar screening were 89.2% and 69% and 93.8% and 96.3%, respectively. Also, 93 CNS isolates were resistant to Methicillin according to disk agar diffusion. DISCUSSION: Our results indicated that agar screening was superior to oxacillin disk agar diffusion. A comparison between the antibiotic sensitivity patterns of the MRCNS and the Methicillin-Susceptible Coagulase-Negative Staphylococci (MSCNS) showed that the MRCNS were predominantly multiple-drug resistant isolates as the simultaneous resistance rate to 4 or more antibiotics in the MRCNS and MSCNS was 93% and 56%, respectively.

Quantitative detection of Staphylococcus aureus, Streptococcus pneumoniae and Haemophilus influenzae in patients with new influenza A (H1N1)/2009 and influenza A/2010 virus infection.

INTRODUCTION: Viral influenza is a seasonal infection associated with significant morbidity and mortality. In the United States more than 35,000 deaths and 200,000 hospitalizations are recorded annually due to influenza. Secondary bacterial infections or co-infections associated with cases of influenza are a leading cause of severe morbidity and mortality, especially among high-risk groups such as the elderly and young children. AIM: The aim of the present study was the quantitative detection of S. aureus, S. pneumoniae and H. influenzae in a group of patients with seasonal influenza A, influenza A (H1N1) pandemic 2009, and patients with symptoms of respiratory infection, but the negative for H1N1 serving as control group. METHOD: In total, 625 patients suspected respiratory infection from April 2009 to April 2010 were studied. There were 58 patients with influenza A H1N1 and 567 patients negative for influenza A H1N1. From November 2010 to February 2011, 158 patients with respiratory symptoms were analyzed for seasonal influenza A. There were 25 patients with seasonal influenza A. To check the colonization status among the healthy individuals 62 healthy persons were further investigated. Individual were screened in parallel. The choices of special genes were amplified from clinical specimens using real-time PCR with a cutoff of 10(4) CFU/mL to differentiate colonization from infection in respiratory tract. RESULTS: S. aureus, S. pneumoniae and H. influenzae were detected in 12%, 26% and 33% of patients with H1N1, while the corresponding figures were 9%, 19%, and 31% for H1N1 negative patients. Among patients with seasonal influenza A 12% S. aureus, 24% S. pneumoniae, and 32% H. influenzae co-infections were detected, while influenza negative control group yielded 5% S. aureus, 11% S. pneumoniae, and 10% H. influenzae, respectively. CONCLUSION: The results of this study indicated that the serotype of pandemic H1N1 2009 did not increase incidence of secondary infection with S. aureus, S. pneumoniae and H. influenzae. Quantitative detection of secondary bacterial infection by QR-PCR can help us for distinguishing colonization from infection and controlling misuse of antibiotics and bacterial drug resistances.

Role of efflux pumps: MexAB-OprM and MexXY(-OprA), AmpC cephalosporinase and OprD porin in non-metallo-ß-lactamase producing Pseudomonas aeruginosa isolated from cystic fibrosis and burn patients.

PURPOSE OF THE RESEARCH: In order to gain a better understanding of the role of several mechanisms in antibiotic resistance in Pseudomonas aeruginosa clinical isolates obtained from CF and burn patients, we evaluated gene expression of efflux pumps MexAB-OprM and MexXY(-OprA), the natural ß-lactamase AmpC and outer membrane porin protein OprD. Also, the presence of genes encoding Ambler classes A, B ß-lactamases and aminoglycoside modifying enzymes (AMEs) was examined. PRINCIPAL RESULTS: Piperacillin-tazobactam and amikacin retained the highest in vitro activities among 21 CF and 27 burn P. aeruginosa isolates. Based on Enterobacterial Repetitive Intergenic Consensus (ERIC) PCR, 15 distinct patterns were detected. There were 5 CF and 6 burn isolates harbored PER-1 and VEB-1, respectively. Among AMEs, involved in resistance of anti-Pseudomonas aminoglycosides, aac(6')-Ib was the most prevalent gene. Among CF isolates, mexA overexpression was the most prevalent mechanism (47.6%) followed by mexX (42.8%), ampC (9.5%) and oprD downregulation (4.7%). Among burn isolates, the prevalence of mexX, mexA, and ampC overexpression was 62.9%, 74%, and 11.1%, respectively. Downregulation of oprD was observed in 14.8% of burn isolates. MAJOR CONCLUSIONS: Among CF isolates, mexX and mexA overexpression were the major contributing factors to aminoglycoside (gentamicin) and carbapenem (meropenem) resistance, respectively while among burn isolates, AMEs in conjunction with mexX hyperexpression were identified to be responsible for aminoglycoside resistance. Also mexA overexpression was partially associated with carbapenem resistance. Moreover, cephalosporin resistance was linked to overexpression of mexA and/or mexX. The impact of interplay between different resistance mechanisms on resistant phenotypes was more complicated among burn than CF isolates.

Prevalence of Ambler class A ß-lactamases and ampC expression in cephalosporin-resistant isolates of Acinetobacter baumannii.

We examined the prevalence of various cephalosporins' resistance mechanisms in Acinetobacter baumannii clinical isolates. Phenotypic and molecular detection of Ambler classes A, B and D ß-lactamases was performed on 75 isolates. Clonal relatedness was defined using Repetitive Extragenic Palindromic PCR. PCR mapping was used to examine the linkage of insertion sequences and the ampC gene, and ampC expression was analyzed by TaqMan reverse transcriptase-PCR. Twenty-six (37%) isolates carried at least one of the blaPER-1 or blaTEM-1. Sixty-nine (98.5%) out of 70 cephalosporin-resistant isolates had insertions upstream of the ampC gene, of which 48 (69%) and 6 (8%) were identified as ISAba1and ISAba125, respectively. Higher level of expression was obtained in resistant isolates lacking ISAba1/ampC combination in comparison with that in positive ones. The ability to up-regulate the expression of ampC gene in association with different insertion elements has become an important factor in A. baumannii resistance to cephalosporins.

Study of the carbapenem resistance mechanisms in clinical isolates of Acinetobacter baumannii: comparison of burn and non-burn strains.

We examined the prevalence of various carbapenem resistance mechanisms in clinical isolates of Acinetobacter baumannii collected from hospitalized burn and non-burn patients. Antimicrobial susceptibility testing was performed for 43 burn and 32 non-burn isolates. Carbapenem resistance genes were identified and repetitive extragenic palindromic PCR (REP-PCR) was used to define clonal relatedness. CarO disruption was investigated by PCR and its expression analyzed by real time reverse transcription-PCR. Of the sixty-four (85%) carbapenem resistant A. baumannii isolates, 42 (66%) and 22 (34%) strains were recovered from burn and non-burn patients, respectively. Isolates were categorized into 6 major REP-PCR patterns; with the highest prevalence of non-burn and burn isolates in pattern A (63%) and B (35%), respectively. Prevalence of blaOXA-23 was 68% and isolates harbored this element belonged to all REP clusters. The blaOXA-40-like was detected in 49% of isolates, with higher prevalence among burn isolates. Three of the four isolates lacked carO gene were cultured from burn patients and level of the carO expression was decreased in carbapenem resistant isolates. These findings show that blaOXA-23 is widely distributed in carbapenem resistant A. baumannii isolates and other resistance mechanisms such as blaOXA-40-like and loss or decreased carO expression could be added in burn strains.

Diversity of Helicobacter Pylori cagA and vacA Genes and Its Relationship with Clinical Outcomes in Azerbaijan, Iran.

PURPOSE: The purpose of this research was to analyze cagA and vacA genotypes status in H. pylori isolates and relationship with clinical outcomes. METHODS: Gastric biopsy specimens were cultured for H. pylori isolation and cagA and vacA genes were detected in these isolates. Data were collected and the results were analyzed using χ2 and Fishers exact tests by SPSS software version. 16. RESULTS: Of the total 115 H. pylori isolates, 79 (68.7 %) were cagA positive and 82 (71.3%) of isolates contained the s1 allele which 33 (28.7%) were subtype s2. s1m2 was the most frequent vacA allelic combination in the H. pylori isolates examined (63 cases), followed by s2m2 (31 cases), s1m1 (19 cases) and s2m1 (2 case). Strains cagA positive were more frequent in peptic ulcer diseases patients than non ulcer diseases patients, as 47 (59.5%) and 32 (40.5%), while cagA negative were low, as 15 (41.7%) and 21 (58.3%), respectively. CONCLUSION: We found that the cagA and vacA status were not related to clinical outcomes in this area. Overall, in the present study, vacA s1/m2, cagA-positive strains were predominant irrespective of clinical outcome, but s2/m1 was rare.

A multiresistant clone of Pseudomonas aeruginosa sequence type 773 spreading in a burn unit in Orumieh, Iran.

Herein, we describe the phenotypic and genotypic characterization of a multiresistant clone of Pseudomonas aeruginosa disseminating in a burn unit in Orumieh, Iran. A total of 58 isolates of P. aeruginosa were collected during August 2007 and June 2008. Minimum inhibitory concentrations (MICs) of P. aeruginosa isolates were determined against 11 antimicrobial agents by E test. Serotyping, pulsed-field gel electrophoresis (PFGE), and multilocus sequence typing (MLST) were used for studying the clonal relationship among the isolates. Antibiotic susceptibility testing revealed that most of the isolates were multidrug resistant and colistin was the antibiotic with the highest activity. Pseudomonas aeruginosa isolates fell into nine different serotypes, and O10 and O11 were the most common. PFGE analyses showed 12 different genotypes and 68.1% of isolates showed more than 80% similarity, indicating possible clonal relatedness. These isolates were found to belong to the same sequence type, ST773. This sequence type has earlier been reported from China, and a double locus variant of this ST has been found earlier in France in a PER-1 extended-spectrum ß-lactamase-producing P. aeruginosa.

Dissemination of aminoglycoside-modifying enzymes and 16S rRNA methylases among acinetobacter baumannii and Pseudomonas aeruginosa isolates.

AIMS: The purpose of the present study was to investigate the diversity of the genes encoding aminoglycoside-modifying enzymes (AMEs) and their associations with resistance phenotypes and clonality in Acinetobacter baumannii and Pseudomonas aeruginosa isolates. METHODS: Seventy six P. aeruginosa and 75 A. baumannii isolates were collected from three University affiliated hospitals in Tehran. MIC determination of amikacin and gentamicin as well as the disk diffusion method for tobramycin, netilmicin, and kanamycin were carried out. Nine AMEs genes and three RNA methylases were investigated in all isolates using the PCR method. Clonality for A. baumannii and P. aeruginosa was investigated using repetitive extragenic palindromic and enterobacterial repetitive intergenic consensus PCR, respectively. RESULTS: aph(3')-VIa (90.6%) and aph(3')-IIb (61.8%) were the most prevalent AME genes in A. baumannii and P. aeruginosa, respectively. Eight (26%) amikacin highly resistant A. baumannii isolates were positive for armA methylase. Phenotypes and clonality did not link to the genetic determinants of resistance to aminoglycosides in our isolates. CONCLUSIONS: AMEs genes are disseminated in different clones of A. baumannii and P. aeruginosa isolates in Iran. Other than AMEs, there are more complex and multifactorial mechanisms that result in aminoglycoside-resistant phenotypes.

Comparison of in Vitro Activity of Doripenem versus Old Carbapenems against Pseudomonas Aeruginosa Clinical Isolates from both CF and Burn Patients.

PURPOSE: The antimicrobial activity of doripenem in comparison of imipenem, meropenem and ertapenem among Pseudomonas aeruginosa isolated from burn and Cystic Fibrosis (CF) patients were determined. METHODS: Metallo-ß-lactamase (MBL) genes in imipenem non susceptible P. aeruginosa isolates were detected using PCR method. The in vitro susceptibilities of doripenem, imipenem, meropenem and ertapenem were determined by Etests. MIC50 and MIC90 for corresponding antibiotics were determined individually in burn and CF isolates. RESULTS: Among isolates which were resistant to imipenem, 16 isolates were positive for the bla IMP gene. All isolates had no bla VIM gene. All MBL producing isolates were excluded. MIC50/MIC90 of doripenem in CF and burn isolates were 0.75/>32 and >32/>32 mg/L respectively. The corresponding values for imipenem in CF and burn isolates were 2/>32 and >32/>32 mg/L, respectively. CONCLUSION: The susceptibility rate of doripenem is higher than that of imipenem and meropenem among P.aeruginosa isolated from CF patients, whereas, there is no difference between the efficiency of doripenem and old carbapenems in non MBL producing P.aeruginosa isolates in burn patients.

Characterisation and clonal dissemination of OXA-23-producing Acinetobacter baumannii in Tabriz, northwest Iran.

The characteristics and molecular epidemiology of carbapenemase genes amongst 68 imipenem-resistant Acinetobacter baumannii isolated from Imam Reza Hospital (Tabriz, Iran) during a 17-month period were studied. All 68 isolates were typed using sequence group-based multiplex polymerase chain reaction (PCR) to compare the clonal relationship of isolates with known international clonal lineages. Repetitive sequence-based PCR was further performed with representative isolates of each clone. PCR and sequencing were performed to detect OXA-type carbapenemases and class 1, 2 and 3 integron genes as well as to confirm the presence of insertion sequence ISAba1 upstream of bla(OXA-23) and bla(OXA-51-like) genes. Sixty-four isolates (94%) belonged to international clone (IC) II, two isolates (3%) belonged to IC I and two isolates (3%) did not belong to known international clones. All isolates carried bla(OXA-51-like), bla(OXA-23) and class 1 integron genes. No other acquired bla(OXA) genes or class 2 or 3 integron genes were detected. Sequence analysis confirmed the presence of bla(OXA-23) as well as the bla(OXA-51-like) variants bla(OXA-66), bla(OXA-69) and bla(OXA-88). ISAba1 was present upstream of the bla(OXA-23) gene in all of the isolates. Clonal spread of OXA-23-producing A. baumannii emphasises the need for appropriate infection control measures to prevent further spread of these multidrug-resistant organisms.

Prevalence of OXA-type ß-lactamases among Acinetobacter baumannii isolates from Northwest of Iran.

Carbapenems have been considered as last line antibiotics for treatment of multidrug-resistant (MDR) Acinetobacter baumannii but carbapenem resistant A. baumannii has been increased during the last decade in many parts of the world. OXA-type ß-lactamase enzymes are the most common cause of carbapenem resistance in A. baumannii and presence of ISAba1 in upstream of these genes may increase the expression of these OXA genes. The aim of this study was to determine, for the first time, the antibiotic resistance pattern and prevalence of OXA type ß-lactamases among nosocomial A. baumannii isolates from northwest of Iran. A total of 100 A. baumannii isolates were recovered from hospitalized patients in a university hospital in northwest of Iran. Sixty-two percent of isolates were resistant to imipenem. All isolates carried bla(OXA-51)-like gene. Among imipenem resistant isolates, 88.7% carried bla(OXA-23)-like, 1.6% carried bla(OXA-40)-like, and 3.2% had bla(OXA-58)-like resistance genes. Ninety percent of isolates contained ISAba1 element and in 74.2% of imipenem resistant isolates, ISAba1 was located in upstream of bla(OXA-23)-like. The results of this study demonstrated high prevalence of OXA-type carbapenemase among MDR A. bumanii in the Northwest of Iran.

High prevalence of metallo-beta-lactamase-producing acinetobacter baumannii in a teaching hospital in Tabriz, Iran.

Metallo-beta-lactamase (MBL)-producing Acinetobacter baumannii has become a growing therapeutic concern worldwide. The aims of this study were to evaluate the antimicrobial susceptibility of A. baumannii isolates and to determine the prevalence of MBL genes among carbapenem non-susceptible isolates. During a period of 16 months (March 2008-June 2009), 100 isolates of A. baumannii were collected from different clinical specimens of inpatients admitted to the largest teaching hospital in the northwest of Iran. All isolates were tested for antimicrobial susceptibility by Kirby-Bauer disk diffusion method. Carbapenem non-susceptible isolates were further screened for production of MBL by Etest and were then subjected to PCR for detection of MBL genes of types bla(IMP) and bla(VIM). Among 63 carbapenem (imipenem and meropenem) non-susceptible isolates of A. baumannii, 31 (49%) were found to be MBL producers. Of 31 MBL-producing isolates, 19 (61%) carried the bla(IMP) gene and 9 (29%) carried the bla(VIM) gene. All MBL-producing isolates were multidrug resistant. This is the first report of IMP and VIM types among MBL-producing A. baumannii in Iran.