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Background: Infections caused by Pseudomonas aeruginosa or Acinetobacter baumannii are of greatest concern for hospitalized patients, particularly those in intensive care units (ICUs). The aims of this study were to investigate the prevalence of integrons and biofilm formation among P. aeruginosa and A. baumannii isolates collected from ICU and non-ICU inpatients.
Materials and Methods: A total of 90 P. aeruginosa and 90 A. baumannii isolates were recovered from patients admitted into diverse units of Shahid Mohammadi hospital in Bandar Abbas from January to December 2014. Bacterial identification was carried out by phenotypic methods and PCR. Antibiotic susceptibility was measured by disk diffusion assay. The presence of Class 1, 2, and 3 integrons were evaluated by multiplex-PCR. Biofilm quantification was done by microtiter method.
Results: The highest number of isolates (48%) were recovered from ICU patients. 81% of P. aeruginosa isolateswere sensitive to piperacillin/tazobactam and ticarcillin, while 60% were resistant to third generation of cephalosporins. In case of A. baumannii, all the isolates were sensitive to colistin, but 98% were resistant to other antibiotics (p≤0.05). Susceptibility to ceftazidime, ticarcillin, imipenem, and piperacillin/tazobactam were higher among isolates obtained from non-ICU patients. Class 1 integron was detected in 13.3% of the P. aeruginosa and 40% of the A. baumannii isolates, while Class 2 integron was harbored by 7 and 6.6% of the isolates, respectively. Furthermore, 23% of the A. baumannii and 12% of the P. aeruginosa isolates showed strong biofilm activity.
Conclusion: Class 1 integron-positive isolates were resistant to three classes of antibiotics and predominantly observed in specimens collected from ICU patients showing strong biofilm.

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Background: The global control of the drug resistance tuberculosis has remained as major challenge. The present study was the first review study in the Middle East region in order to determine levels of Mycobacterium tuberculosis resistance to the first-line anti-TB drugs among both new and previously treated cases.
Materials and Methods: The computer-assisted search was performed by using PubMed, Google Scholar, Scopus databases and related keywords. Within the time span of 1981-2014, a total of 480 articles were collected on the antibiotic resistance rates of M. tuberculosis in different countries of the Middle East region. About 63 relevant articles were selected by applying inclusion and exclusion criteria.
Results: By using meta-analyses, we determined mono drug resistance, any drug resistance, and multidrug resistance (MDR-TB) rates in both new and previously treated TB patients living in different parts of the Middle East. Other aspects related to patients, antimicrobial resistance, and methods used to assess the resistance rate were also analyzed.
Conclusion: The present study revealed that in comparison with the global average rate, the prevalence rate of drug resistant TB, especially MDR-TB, may be increasing in the Middle East. Therefore, in order to prevent the spread of drug-resistant isolates, detecting primary resistance to anti-TB drugs with the use of new rapid diagnostic methods is necessary.

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Background: Integrons are considered as to play a significant role in the evolution and spread of antimicrobial resistance genes.
Materials and Methods: A total of 120 clinical isolates of Pseudomonas aeruginosa (collected from Zanjan hospitals between March 2015 and February 2016) were investigated for molecular characterization of MBLs and Class I and II integrons. Antimicrobial susceptibility testing was also performed based on the CLSI guidelines. The frequency of MBL producing isolates and the susceptibility to various antimicrobial agents were investigated.
Results: Based on the obtained results, Bla_IMP was the most frequently detected metallo-β-lactamase. The frequency of bla_VIM, blaSPM, and bla_SIM, in MBL producing isolates was 17.1, 57.1, and 14.1%, respectively. No bla_GIM harboring isolate was detected in our study. We detected two (5.7%) multidrug resistant P. aeruginosa strains isolated from the urine and sputum samples, which harbored bla_NDM-1. These isolates also contained bla_IMP and bla_SPM. Class I integron was detected in 94.3% of the MBL positive isolates while 8.5% of the isolates contained Class II integrons. Of five different gene cassettes identified in Class I and II integrons, cassette encoding resistance to trimethoprim (dfr) was found to be predominant.
Conclusion: These results indicate that Class I integrons are widespread among the MBL producing P. aeruginosa isolates. Therefore, appropriate surveillance and control measures are essential to prevent the further spread of MBL and integron producing P. aeruginosa in hospitals.­­

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Background: Klebsiella pneumoniae is a Gram-negative bacterium and a part of the natural microflora of gastrointestinal tract in human body. K. pneumoniae has been known as one of the most common cause of nosocomial infections and multi-drug resistance pathogen. The aims of this study was to examine the detection of antimicrobial susceptibility and genetic relatedness among K. pneumoniae strains isolated from hospitals in Borujerd in western Iran using Enterobacterial Repetitive Intergenic Consensus (ERIC)–PCR technique.
Materials and Methods: A total of 100 K. pneumoniae isolates were collected from Borujerd hospitals from April to September 2015. After detection and confirmation of K. pneumoniae isolates by conventional laboratory methods and differential tests, antibiotic susceptibility was detected by disk diffusion method. Also, genetic relatedness of 34 selected MDR K. pneumoniae isolates were investigated by ERIC - PCR technique.
Results: Antibiotic susceptibility testing showed that among K. pneumoniae isolates, the highest antibiotic resistance was observed in ampicillin (91%) and the highest susceptibility was detected in imipenem (5.5%). More than 45% of isolates showed multi resistant phenotypes. Based on ERIC-PCR results, 31 different ERIC types were detected.
Conclusion: The results of this study indicate the increase of multi resistance K. pneumoniae in hospitals under study. The results of ERIC PCR showed high genetic diversity among K. pneumoniae strains, which indicated the poly clonal distribution of K. pneumoniae isolates in Borujerd hospitals.

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Background: Enterococci play an important role in the spread of drug resistant genes and thus resistant strains. The dissemination of vancomycin-resistant Enterococci (VRE) strains is one of the crucial issues in hospitals worldwide, especially among those hospitalized patients. This study aimed to assess the antibiotic resistance pattern and the prevalence rates of vanA, vanB, and vanC genes among Enterococcus faecalis strains isolated from meat.
Materials and Methods: This cross-sectional study was performed on 181 isolates of E. faecalis isolated from consumed meat samples in Borujerd city. Antibiotic susceptibility testing was performed using the disk diffusion method according to CLSI criteria. The prevalence rate of vanA and vanB genes in vancomycin resistant E. faecalis strains was identify by PCR technique.
Results: Of 181 Enterococci isolates, 100 strains (55.25%) were E. faesium, and 81 strains (44.75%) were E. faecalis. About 13 antibiotics were used in this study. The highest resistance was observed against erythromycin, linezolid, vancomycin, and penicillin antibiotics, and the lowest resistance was observed against meropenem; none of the isolates were resistant to nitrofurantoin and cefotaxime. A total of 68 isolates (83.95%) were resistant to vancomycin. Among the isolates, 38 isolates (46.9%) contained vanA gene, 21 isolates (25.9%) carried vanB gene, and 18 (22.2%) isolates contained vanA and vanB genes, but van C type was not detected in none of the isolates.
Conclusion: The presence of van gene in the majority of isolates is an indicator of resistant genes large reservoir in the strains rotation in the community. Furthermore, in order to limit the incidence of VRE, the use of antibiotics for human or animal should be taken with caution.

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Aims: There are few data regarding the prevalence and trends of Klebsiella pneumoniae antibiotic resistance in Algeria. The present study was conducted to investigate the spatial distribution of K. pneumoniae antibiotic resistance phenotypes in time and according to specimen source.   
Materials & Methods: This retrospective study was performed between January 2011 and December 2015 at Mila Hospital, Algeria. A total of 172 K. pneumoniae were isolated from consulting and hospitalized patients, and their antimicrobial susceptibility was tested. The Principal Component Analysis (PCA) was used to study correlations among antimicrobial resistance phenotypes observed, and Factorial Correspondence Analysis (FCA) was used to study the spatial distribution of antibiotic resistance phenotypes according to specimen source.
Findings: The specimens were obtained from urine (n=89), vagina (n=39), pus (n=33), blood (n=9) and surgery (n=2). PCA showed two principals associations of resistance phenotypes gathered in two clusters. The first profile regroups amoxicillin-clavulanic acid, cefazolin and ampicillin. The second assembles cefotaxime, nalidixic acid and sulfamethoxazole-trimethoprim. In FCA, nalidixic acid was connected with urine specimens, registering maximum resistance (52.8%) compared to the other samples. Vagina specimens were associated to sulfamethoxazole-trimethoprim and colistin phenotypes registering maximum resistances with 89.7 and 76.9%, respectively. Pus manifested a near association to cefotaxime with a maximum resistance (48.5%).
Conclusion: The model developed in FCA, highlights typical associations of antibiotic resistance phenotypes to specimen source and confirms the difference in resistance profile according the source of specimen in K. pneumoniae infections.

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Aims: Nowadays, treatment of bacterial infections is one of the most important challenges in the world. Medicinal plants offer a great hope to overcome these needs because of their chemical diversity and their significant role in the drug development. The aim of this study was to evaluate the in vitro antibacterial activity of the thyme (Thymus vulgaris) essential oil against Mycobacterium tuberculosis.
Materials and Methods: In this experimental study, thyme herb plants were collected and thyme essential oil was extracted. The Minimum Inhibitory Concentration (MICs) tests were performed to determine the antimicrobial activity of Thymus plant against the first (Isoniazid, Rifampicin, Ethambutol) and second (Cycloserine, Streptomycin, Kanamycin) drug antibiotics of mycobacterium. Data were analyzed by SPSS 21 software, using one-way ANOVA test.
Findings: The MICs for Isoniazid, Ethambutol, Streptomycin and Cycloserine were less than 10µg/ml and the MIC values for Rifampicin and Kanamycin were 40µg/ml. The limits of minimal inhibitory concentration of essential oil was between 0.5-40µg/ml (p<0.05).
Conclusion: Thyme essential oil has antibacterial activity against Mycobacterium tuberclusis.

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Aims: Methicillin-resistant Staphylococcus aureus (MRSA) is recognized as an important health problem worldwide. To counteract the human innate immunity, S. aureus produces a number of immune evasion cluster (IEC) including staphylokinase (SAK), staphylococcal enterotoxin P (SEP), staphylococcal enterotoxin A (SEA), staphylococcal complement inhibitor (SCIN), and chemotaxis inhibitory protein (CHIP) encoded by sak, sep, sea, scn, and chp genes, respectively. These genes are carried by β-hamolysin-converting bacteriophages. The present study was conducted to determine the IEC phage types and antibiotic resistance patterns in 145 clinical MRSA isolates from Khuzestan Province, Iran.
Methods: All the isolates were investigated by disc diffusion method and PCR assay of sak, sep, sea, scn, and chp genes.
Findings: The assessment of antibiotic resistance showed the highest rate of resistance towards penicillin (97.25%), followed by methicillin (95.8%), ceftazidime (81.4%), erythromycin (71.8%), clindamycin (61.4%), ciprofloxacin (60.7%), gentamycin (56%), imipenem (56.55%), and vancomycin (0%), respectively. Also, the frequency of IEC types was as follows: type A (4.8%), type B (9%), type C (13.1%), type D (12.4%), type E (27.6%), type F (1.4%), type G (0.7%), and type H (6.9%). On the other hand, 24.1% of the isolates did not show any of the IEC types.
Conclusion: The findings showed that IEC-carrying bacteriophages are highly prevalent among MRSA strains, resulting in the adaptation and counteraction of bacteria to the human immune system. Therefore, understanding the role of IEC in the virulence of bacteria can improve our knowledge about the evolution, vaccination, and treatment of S. aureus infection.

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Background: Bacterial meningitis is a devastating infection associated with significant morbidity and mortality rate among neonates and young children. Early identification and treatment of the causative agents of meningitis is crucial due to high fatality rate in untreated cases. The present study aimed to investigate the common bacterial etiology and occurrence of antimicrobial resistance in patients suspected to meningitis in southwestern Iran.
Materials & Methods: This retrospective cross-sectional study was conducted during a five-year period from January 2011 to January 2016 at two major hospitals in southwestern Iran. CSF samples were aseptically collected in BACTECTM, and conventional methods were used for the bacteria isolation and identification. Antimicrobial susceptibility tests were done using disk diffusion and E-test methods.
Findings: Out of 89 CSF samples collected from children under 17 years, the number of culture positive specimens was 21 (23.6%). The highest number of culture positive cases was observed in patients younger than 5 years (57.1 %). The most frequent pathogens were Streptococcus pneumonia (N = 10, 47.6%), followed by Haemophilus spp. (N = 3, 14.3%), and Neisseria meningitidis (N = 3, 14.3%). Antibacterial susceptibility testing results showed that S. pneumoniae isolates were mostly susceptible to vancomycin and chloramphenicol. Moreover, among N. meningitides and Haemophilus isolates, the most effective in vitro drug was ceftriaxone (100%).
Conclusions: These results showed the promising activity of several locally available antibiotics against S. pneumoniae, Haemophilus spp. and N. meningitides, as the most common causative agents of bacterial meningitis in Iranian children. Therefore, such regional studies help prevent and control the burden of infections.

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Backgrounds: Sepsis is a systemic inflammatory response syndrome triggered by an infectious agent and an important cause of admission to intensive care units (ICU), especially in immunodeficient patients. The aim of this study was to determine the spectrum of bacterial etiology and antibacterial susceptibility pattern of sepsis and urinary tract infections (UTIs) in Iranian HIV-infected patients.
Materials & Methods: This retrospective cross-sectional study was conducted on HIV/AIDS patients for a period of ten years from January 2005 to January 2015 at two major hospitals in southwestern Iran. Standard microbiological methods were used for the isolation and identification of bacteria from samples. Antimicrobial susceptibility tests were done using disk diffusion method.
Findings: Out of 228 samples collected, the frequency of culture-positive blood and urine samples was 23.2% (n = 53) and 9.6% (n=22), respectively. Among culture-positive blood samples, Staphylococcus aureus (N = 17, 32.1%) and Pseudomonas (N = 5, 9.4%) were the main etiologic agents. While among 22 culture-positive urine samples, the predominant bacteria were Enterococci (N = 7, 31.8%) and Escherichia coli (N = 5, 22.7%). Antibacterial susceptibility testing results showed that Gram-positive bacteria were mostly susceptible to vancomycin, rifampin, and co-trimoxazole; meanwhile, Gram-negative bacteria were mostly susceptible against tobramycin, amoxicillin/clavulanate, and aztreonam.
Conclusions: In summary, this study findings highlighted the emergence and spread of opportunistic infections and a high level of antibiotic resistance among HIV-infected patients; therefore, restricted infection control strategies must be pursued in these hospitals.

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Aims: Following the emergence of methicillin-resistant Staphylococcus aureus (MRSA) isolates, the use of other antibiotics especially vancomycin in S. aureus infections has become inevitable, leading to the emergence of vancomycin-resistant S. aureus (VRSA) strains, which is considered as a major public health concern. This study aimed to determine the vancomycin susceptibility patterns of S. aureus clinical isolates in order to evaluate the current status of vancomycin resistance in the southwest of Iran.
Materials & Methods: In this study, 100 S. aureus clinical strains were collected from the hospitals of Khuzestan province in the southwest of Iran. Next, antibiotic susceptibility, vancomycin resistance, and the presence of mecA, vanA, vanB, vanC, and vanD genes were investigated in these isolates.
Findings:  It was found that 1 and 2 isolates were vancomycin-intermediate S. aureus (VISA) and VRSA, respectively. All three strains showed methicillin-resistance pattern and carried mecA gene. vanA gene was detected in VRSA strains, whereas vanB, vanC, and vanD genes were detected in none of these isolates.
Conclusion: This study findings could be alarming regarding the emergence and spread of VRSA strains; therefore, the principles of infection control should be employed in the healthcare systems to prevent the spread of VRSA strains in healthcare facilities.
 

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Aims: This study aimed to determine the antibiotic resistance pattern of Pseudomonas aeruginosa clinical isolates and the frequency of blaSIM and blaAmpC genes in resistant strains.
Materials & Methods: In this cross-sectional study, 94 P. aeruginosa isolates were collected from the burn wards of Gilan province hospitals in 2018 and identified by biochemical methods. Strains producing β-lactamases and metallo-β-lactamases were detected by two methods: disk diffusion method and antibiotic resistance method in combination with disk diffusion method, respectively. The presence of blaSIM and blaAmpC genes in the resistant strains was investigated using PCR, and data analysis was performed.
Findings: Based on the obtained results, colistin was identified as the most effective antibiotic with a resistance rate of 27.7%, and the highest antibiotic resistance was observed against trimethoprim/sulfomethoxazole (83%). In the phenotypic test of 94 samples, 29 (30.9%) carbapenemase-producing isolates and 33 (35.1%) β-lactamase-producing isolates were identified. Based on the PCR results, among 44 (46.8%) samples containing β-lactamase and carbapenemase enzymes, the frequency of blaSIM gene was 9.1% (4 of 44, and 4.3% in all the studied isolates), and the frequency of blaAmpC gene was 15.9% (7 of 44, and 7.4% in the all studied isolates).
Conclusion: The results of this study indicated a high prevalence of drug resistance in clinical isolates of P. aeruginosa. In particular, there was an increasing rate of resistance to beta-lactam antibiotics, and the presence of MBL and ESBL associated genes was considerable, which limit the choice of suitable treatment for patients with severe infections.

 

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Aims: Acinetobacter baumannii is an opportunistic pathogen that is resistant to many antibiotics including beta-lactams. Production of β-lactamases is the main mechanism of β-lactam resistance in A. baumannii strains. The aim of this study was to determine the frequency of blaTEM and blaVEB genes in clinical isolates of A. baumannii and the relationship between the antibiotic resistance and the presence of ESBL genes in strains isolated from burn wound infection in Isfahan.
Materials & Methods: In this study, 123 MDR A. baumannii strains were isolated from burn wound infection. After antibiotic resistance evaluation using the Kirby-Bauer disc-diffusion method, all the isolates were evaluated with polymerase chain reaction (PCR) technique to detect ESBL genes, followed by statistical analysis by the end.
Findings: Out of 123 A. baumannii isolates, 77 (62.60%) strains were ESBL positive according to the PCR results. The frequency of blaTEM and blaVEB genes was 52 (42.3%) and 67 (54.5%), respectively. There was a significant relationship between the antibiotic resistance and the presence of ESBL genes (blaTEM and blaVEB) in A. baumannii strains.
Conclusion: The high prevalence of blaTEM and blaVEB genes in A. baumannii strains found in this study is the major concern about burn wound infections in Isfahan and Iran because of the complexity in treating infections caused by these strains. This study results highlighted the need for infection control measures to prevent the spread of resistant isolates and ESBL genes, especially in burn hospitals.

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Aims: Numerous microbial agents have been identified as the causative agents of UTIs, such as Escherichia coli. The spread of antibiotic resistance is increasing among strains causing UTIs. The present study aimed to investigate the prevalence of etiological agents of UTIs and their antibiotic resistance patterns and to determine related risk factors and treatment outcomes of antibiotic resistance in Razi teaching hospital, Guilan, North of Iran.
Material & Methods: This retrospective cross-sectional study was performed from April 2017 to September 2018. All patients with clinical symptoms of UTI were included. The patients’ complete medical records were assessed. Moreover, bacterial isolation and identification were performed by conventional bacteriological and standard biochemical tests. Antibiotic susceptibility testing was performed using the disk diffusion method based on the CLSI recommendation.
Findings: Gram-negative bacilli were identified as the most common causative agents of UTIs in all cases (140, 100%), of which E. coli had the highest isolation rate with 76 cases (54.3%), followed by Klebsiella spp. with 23 cases (16.4%).  Antibacterial susceptibility tests revealed that 64.3% of the isolates were resistant to three antibiotics of different classes (MDR phenotype).
Conclusion: In conclusion, Gram-negative bacilli were the most common causative agents of UTIs, and E. coli had the highest isolation rate (54.3%). Regarding the high prevalence of antibiotic resistance and MDR phenotype, paying attention to drug resistance patterns of pathogens and proper and correct administration of antibiotics as well as proper and timely monitoring of treatment, could help physicians decrease the patients’ mortality rate.

 

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Backgrounds: A common problem among diabetic patients is foot ulcers and infections, impacting up to 15% of diabetic patients over their lifetime. The aim of this study was to investigate the frequency of bacterial agents and their antimicrobial resistance pattern in patients with diabetic foot infection in Namazi and Shahid Faghihi hospitals in Shiraz.
Materials & Methods: This cross-sectional study was conducted in Namazi and Shahid Faghihi hospitals in Shiraz. The collected samples were transferred to the laboratory for culture and biochemical tests. After accurate identification of bacterial agents, antibiotic susceptibility of all isolated bacteria was evaluated by disk diffusion method based on CLSI guidelines. Data were analyzed using SPSS software (Version 19).
Findings: In this study, 166 patients with diabetic foot ulcers were evaluated. The mean age of patients was 55.8± 13.2 years, and 109 (66.4%) cases were male. Also, 62% of patients had an underlying disease, while most of them had hypertension (27%). The most prevalent isolated bacterium was Staphylococcus epidermidis. The most effective antibiotics against isolated Gram-positive and Gram-negative bacteria were vancomycin and amikacin, respectively.
Conclusion: In this study, it was concluded that the frequency of Gram-negative bacteria in diabetic foot ulcer infections was higher than that of Gram-positive bacteria.

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Backgrounds: In recent years, Enterococcus species have emerged as a leading cause of nosocomial infections worldwide. The aim of this study was to determine the virulence biomarkers and antibiotic resistance profiles of Enterococcus spp. collected from a main tertiary teaching hospital in Bandar Abbas, Iran.
Materials & Methods: A total of 71 Enterococcus were isolated from clinical specimens of patients in different wards of a hospital. Enterococcus spp. were verified by detecting ddl gene using PCR-based method. Virulence-encoding genes including gelE and cylA were detected using PCR. Antibiotic resistance was assessed using the disk diffusion assay, and vancomycin resistance was identified using the E-test method.
Findings: Among Enterococcus isolates, 50 and 21 isolates were identified as E. faecalis and E. faecium, respectively. Most of the Enterococcus species were isolated from urine, followed by wound samples. The most prevalent virulence genes among E. faecalis isolates were cylA (60%) and gelE (30%); also, 19 and 14% of E. faecium isolates were positive for cylA and gelE genes, respectively. Many isolates of E. faecalis (84%) and E. faecium (76%) were resistant to one or more antibiotics and showed high resistance to gentamicin and ciprofloxacin.
Conclusion: This study revealed a high prevalence of ciprofloxacin and gentamicin resistance and a high frequency of virulence genes among E. faecalis isolates. Due to the high prevalence of MDR Enterococcus strains, control measures are necessary to prevent the emergence and transmission of these strains in different hospital wards.
 

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Backgrounds: Group B Streptococcus (GBS) is an important opportunistic bacterial pathogen that could cause serious infections, especially in neonates, adults, and the elderly. In GBS isolates, a macrolide resistance phenotype that confers constitutive resistance to macrolide-lincosamide-streptogramin B antibiotics (cMLSB phenotype) has become a global concern. On the other hand, little is known about the genetic relatedness and diversity of GBS isolates isolated from various patients in Iran. Hence, this study aimed to determine the genetic relatedness and molecular typing of cMLSB-GBS isolates using enterobacterial repetitive intergenic consensus-PCR (ERIC- PCR) technique.
Materials & Methods: A total of 100 GBS isolates were collected from patients with urinary tract infections (UTI).  Among them, 52 erythromycin-resistant GBS isolates were selected, and double-disc diffusion (D-zone) technique was applied to determine the MLSB phenotype among the isolates based on CLSI criteria. Then the genetic relatedness of MLSB-GBS isolates was assessed using ERIC-PCR fingerprinting method.
Findings: Among 52 erythromycin-resistant GBS isolates, 38 isolates were identified with cMLSB phenotype, nine isolates with M phenotype, and five isolates with iMLSB phenotype. The analysis of ERIC-PCR patterns revealed eight different ERIC types that were divided into seven clusters (A-G) and one single type. Also, four isolates were non-typeable. ERIC type A/ serotype Ib was the most prevalent clone among the isolates.
Conclusion: The current study findings showed a high level of diversity and multiclonal spread of the cMLSB phenotype in Isfahan. ERIC type A/ serotype Ib is the predominant clone circulating among erythromycin-resistant GBS strains.

 

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Backgrounds: The aim of this study was to evaluate genotypes and phenotypes of antibiotic resistance in Escherichia coli (E. coli) strains isolated from poultry farms in Isfahan province, Iran.
Materials & Methods: In this study, 50 E. coli strains isolated from pericarditis and perihepatitis lesions of broilers in Isfahan (central Iran) were selected. After microbiological and biochemical tests and confirmation of bacterial colonies, the colonies were purified. The pure colonies were cultured on Müeller-Hinton culture medium and then subjected to antibiotic susceptibility testing. In the next step, DNA was extracted from the purified bacteria, and the qnrA and sul1 genes were amplified with specific primers.
Findings: The results showed that 85% of E. coli isolates were resistant to at least two antibiotics, and 6% of E. coli strains were resistant to all 13 antibiotics used in this study. E. coli isolates showed the highest resistance to enrofloxacin (70%) and the lowest resistance to gentamicin (6%). Examination of resistance genes showed that about 54% of enrofloxacin-resistant E. coli strains contained the qnrA gene, and 48% of sulfonamide-resistant E. coli strains contained the sul1 gene.
Conclusion: In this study, some resistant strains lacked the resistance genes studied, indicating the importance of other resistance genes in inducing resistance against sulfonamides and fluoroquinolones. Also, the lack of resistance in some strains harboring qnrA and sul1 genes indicates the importance of gene expression in mediating resistance, and that the presence of resistance genes alone is not sufficient to induce antibiotic resistance in E. coli strains.

 

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Aims: Acinetobacter baumannii could develop resistance through different mechanisms, leading to the emergence of strains resistant to all commercially accessible antibiotics. This research aimed to evaluate the antimicrobial resistance pattern and the prevalence of genes encoding quinolone resistance in quinolone-resistant isolates.
Methods: In this study, 114 A. baumannii strains were isolated from patients admitted to a teaching hospital in Kashan, during 2013-2014. Antimicrobial susceptibility testing was performed using the Kirby-Bauer disk-diffusion breakpoint assay. Polymerase chain reaction (PCR) was employed to identify quinolone resistance encoding genes (gyrA and parC).
Findings: All A. baumannii strains showed resistance to piperacillin, ceftriaxone, ceftazidime, and cefotaxime, and all of them were susceptible to colistin and polymyxin B. In addition, 100% of A. baumannii strains were MDR (Multi-drug resistance), and 68.4% (78 isolates) of them were XDR (Extensively-drug resistant), while none of them were PDR (Pan-drug resistant). All A. baumannii strains isolated in this study were positive for the presence of parC and gyrA genes.
Conclusion: MDR A. baumannii strains were highly prevalent among hospitalized patients in this study. Based on these comes about, novel prevention and treatment procedures against A. baumannii infections are justified. Moreover, these information may help in reexamining treatment rules and territorial arrangements in care units to moderate the rise of antimicrobial resistance.