2023 Impact Factor: 1.3
2023 CiteScore: 2.4
pISSN: 2008-3289
eISSN: 2008-4447
Chairman and Editor-in-Chief:
Mohammad Mehdi Feizabadi
This journal is a member of, and subscribes to the principles of, the Committee on Publication Ethics (COPE).
Vol 10 No 1 (2018)
Original Article(s)
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Background and Objectives: Clostridium difficile infections (CDI) include self-limiting antibiotic associated diarrhoea (AAD), antibiotic-associated colitis, and pseudomembranous colitis. The present study aimed at detecting C. difficile toxin in stool samples of patients with AAD and analyzing the antibiotic use and presence of other risk factors in these patients.
Materials and Methods: In this study, which was conducted on 660 samples, a 2- step strategy was used. In the first step, glutamate dehydrogenase (GDH) was detected in stool samples by enzyme- linked immunofluorescent assay (ELFA). In the second step, GDH positive samples were tested for C. difficile toxin A and B by ELFA. Nucleic acid amplification test (NAAT) was also performed on few samples that were found to be GDH positive and toxin negative or equivocal by ELFA.
Results: Of the 660 samples screened, toxin was detected in 8.8% (58/660) by ELFA and 9.7% (64/660) by NAAT. GDH was detected in 23.8% (157/660) and toxin in 36.9% (58/157) of the GDH positives. Most of the toxin positive patients were on one or more antibiotics prior to developing diarrhoea. The implicated antibiotics were meropenem, amikacin, colistin and cephalosporins. Diabetes, hypertension, use of proton pump inhibitors, previous hospitalization, malignancy and chemotherapy were found to be the risk factors in our study.
Conclusion: Prevalence of GDH was 23.8% (157/660) by ELFA. Toxin prevalence was 9.7% (64/660). Detection rates of C. difficile associated diarrhoea (CDAD) increased with inclusion of NAAT testing by ELFA. -
Background and Objectives: Methicillin-resistant coagulase-negative staphylococci (MR-CoNS) are important nosocomial pathogens. They may serve as a reservoir of SCCmec, the genomic island encoding amongst other methicillin resistance. This study was designed to determine the distribution of different SCCmec types from MR-CoNS isolated from clinical specimens in a tertiary hospital in central Iran, having high frequency of nosocomial methicillin-resistant staphylococcal infections.
Materials and Methods: We evaluated isolates from patients attending the Vali-Asr Hospital located in the center of Iran, from February to December 2012. Multiplex PCR was performed for SCCmec typing. For isolates in which SCCmec could not be typed directly, additional ccr and mec complex analyses were performed.
Results: Totally, 70 MR-CoNS isolates, comprising of 47 S. epidermidis strains (67%), 10 S. saprophyticus (14.3%), 9 S. hemolyticus (13%) and 4 S. lugdunensis (5.7%) were identified. Thirty-nine were characterized as type IVa 19 (27%), type III 11 (16%), type II 7 (10%) and type V 2 (3%). Only 20 isolates (28.6%) carried the ccr complex, while the current methods could not characterize the 11 remaining isolates.
Conclusion: A high level of SCCmec genetic diversity was found among MR-CoNS isolates. MR-CoNS may act as a reservoir of SCCmec IV for MRSA. This issue should be taken into consideration seriously. -
Background and Objectives: Staphylococcus aureus is an opportunistic human pathogen that causes a variety of diseases. Staphylococcal biofilms are a source of chronic and continual infections. This study was conducted to estimate the distribution of agr among different isolates of S. aureus and their relationship with biofilm. Also, it was aimed to check the association of operon agr with virulence factors (seb, eta, spa and tst v8) and study the effect of biosynthesis silver nanoparticles on the function of the agr system.
Materials and Methods: Out of 580 clinical specimens, 100 S. aureus isolates were isolated and identified based on cultural, morphological, and different biochemical tests, in addition to molecular identification using PCR with specific primer 16SrRNA. For biofilm detection, the fungi synthesized silver nanoparticles were used to check its effect on agr system.
Results: The biofilm producer among S. aureus was 61% and non-biofilm producer isolates were 39%. It was found that the total number of agr - bearing isolates was 31 (50.82%), with a significant difference in the distribution percentage of virulence factors genes in isolates of biofilm-forming S. aureus carried agr. The results also revealed a relationship between the agr-quorum sensing system and the prevalence of virulence genes in the isolated S. aureus. Silver nanoparticles (AgNPs) were synthesized by Agaricus compestris, and it was found that it activates the agr system in 31 (100%) of biofilm-forming and carrying operon agr after treatment with sub-MIC of AgNPs.
Conclusion: The findings of this study revealed that not all isolates of S. aureus have agr system. Also, it was found that AgNPs have a positive effect on bacterial virulence factors production and could be used for treatment or in cooperation with antibiotics to decrease resistance -
Background and Objectives: Integrons play a major role in the transmission and accumulation of resistance factors in multidrug resistant bacteria. This study was aimed to evaluate the gene cassettes of class I integron and antimicrobial resistance in isolates of Citrobacter with multidrug resistance (MDR).
Materials and Methods: Ninety isolates of Citrobacter spp. were collected from the largest hospital in Kermanshah, Iran. Antimicrobial resistance patterns were determined using disc diffusion method. The class I integron were detected by PCR. The integrase positive isolates were further analyzed for the presence of gene cassettes using 5' and 3' conserved sequences (CSs) primers and PCR products were sequenced. The data were analyzed using the chi-square test.
Results: Of 90 Citrobacter isolates, 46 (51.1%) were multidrug resistant. Class I integron and gene cassettes were determined in 30 isolates (65.2%). Gene cassettes were found which contained genes encoded resistance to aminoglycosides and trimethoprim and a putative gene. Gene cassettes of dfrA12-orfF-aadA2, dfrA1-aadA1, aadA1 and dfrA15-aadA2 were also found in Citrobacter isolates.
Conclusion: Our results indicate there is a high frequency of class I integron among multi-drug resistant strains of Citrobacter isolated from clinical settings. A high frequency of class I integron associated gene cassettes, in particular dfr and aadA, present in MDR strains of Citrobacter. This data indicates an important role of integrons in the creation and transmission of MDR strains in health care centers. -
Background and Objectives: Different serotypes of Haemophilus influenzae is now divided into 2 divisions: encapsulated and unencapsulated. Multiple locus variable number tandem repeat analysis (MLVA) includes such specifications as the extra power of separation, ease of data interpretation, and epidemiological data accordance, which have made it an appropriate molecular device for good typing and phylogenetic analysis of bacterial pathogens.
Materials and Methods: In this research, cultured samples were studied and strains identified through biochemical tests were recognized. Moreover, DNA was extracted and studied qualitatively and quantitatively. Four pairs of specialized primers related to H. influenzae variable number tandem repeats (VNTR) and preparation of PCR were designed according to the regulated program. Also, electrophoresis of PCR products was performed. Finally, the interpretation of electrophoresis gel was done with respect to the observable bands showing the presence or absence of the required sequence in the samples related to every primer.
Results: This study was the first MLVA typing of the unencapsulated H. influenzae in Iran. In this research, the VNTR sequences were tested in 30 strains without the unencapsulated H. influenzae. Among 30 mentioned strains, for which MLVA profile was obtained in this research, 25 different MLVA types were observed. Likewise, there was no repetition in VNTR sequences resulting from PCR in few H. influenzae. In all these cases, the number of repetitions in MLVA profile was determined as 0, except for one of the primers in 4 strains, which was 16%. However, this did not occur for the other VNTRs.
Conclusion: The highest diversity of the repeats was for VNTR5 (7 types), followed by VNTR6 with 6 types of repeats, and VNTR12-1 and VNTR12-2 with 3 different types. -
Background and Objectives: Urinary tract infections are common infections that can be caused by many bacterial pathogens. The susceptibility of such pathogens to antimicrobial agents is identified by different methods including disk diffusion test, direct sensitivity testing and determination minimum inhibitory concentration. The present study was conducted to isolate and identify bacteria cultured from urine samples and compare the results of direct sensitivity test (DST) against Kirby-Bauer’s disk diffusion antimicrobial sensitivity (AST) with respect to reliability, time and cost.
Materials and Methods: Midstream urine samples were inoculated on blood and MacConkey agar plates; growth was evaluated after colony counting. We identified isolates based on their cultural and biochemical properties, and Vitek® 2 system.Both DST and AST were performed on Mueller-Hinton agar using 10 antimicrobial agents. Error rate was calculated between the DST and AST as the proportion of comparisons between DST and AST test results. The comparisons represented as "very major error", "major error", or "minor error" and "agreement" (i.e, no error).
Results: We tested 373 urine samples, of them 257 (68.9%) were from females and 116 (31.1%) from males. Primary cultivation detected growth (>105 cfu/mL) from 206 (55.23%) samples; Gram-negative isolates were the most common isolates; these included Escherichia coli (111, 51.87%), and Klebsiella pneumoniae (19, 8.88%), while Staphylococcus aureus (14, 6.54%) was the main Gram-positive isolate. From the 1940 individual comparisons of DST and AST of single (pure) bacterial isolates, 12 comparisons (0.6%) represented very major errors, 9 (0.5%) major errors, 36 (1.8%) minor errors, and 1883 comparisons (97.1%) were in agreement.
Conclusion: E. coli was the most common isolate. Cefixime and cefpodoxime were found to be the most ineffective antimicrobial agents, while meropenem and nitrofurantoin were the most effective agents against all isolated urinary pathogens. DST and AST almost give the same results in pure cultures, and direct antimicrobial susceptibility for urine specimens can safely replace standard antimicrobial susceptibility in urinary tract infection. -
Background and Objectives: Salmonellosis caused by Salmonella spp. is one of the most important zoonotic diseases and transmits to human through raw food animal products including poultry meat. Salmonella enterica serovar Enteritidis and Salmonella enterica serovar Typhimurium are the most important strains that infect human. This study was conducted to evaluate the contamination rate of poultry carcasses with S. Enteritidis and S. Typhimurium using multiplex PCR assay.
Materials and Methods: 100 samples were selected during the summer and fall of 2010 by cluster sampling method from 10 broiler flocks, which were slaughtered in a poultry abattoir located in Mashhad suburb. After culturing the samples in enrichment and selective media and obtaining suspected colonies, DNA was extracted and Salmonella isolates were identified by multiplex-PCR. Three sets of primer pairs tagreting invA gene for Salmonella genus, prot6 gene for entritidis serovar and fliC gene for Typhimurium serovar were used.
Results: The contamination of poultry carcasses with Salmonella was 14% (14/100) which 43% (6/14) of them were identified as S. Enteritidis and 36% (5/14) identified as S. Typhimurium, respectively.
Conclusion: Results of this study indicated that the risk of zoonotic diseases created by S. Enteritidis and S. Typhimurium is relatively high in poultry carcasses. -
Background and Objectives: Salmonellosis due to multi-drug resistant Salmonella Typhimurium with biofilm formation ability is a serious public health threat worldwide. Studies have shown that medicinal plants inhibit the growth of bacterial species. The present study aimed at determining antibiotic resistance pattern and biofilm formation ability of S. Typhimurium isolated from poultry flocks. Moreover, the antibacterial activity of Licochalcone A (LAA) and Epigallocatechin-3-gallate (EGCG) against the studied isolates were investigated in this study.
Materials and Methods: Antibiotic susceptibility testing of S. Typhimurium RITCC1730 and 23 clinical isolates of S. Typhimurium against 8 antibiotics was performed using standard Kirby-Bauer disc diffusion method. The extent of biofilm formation was measured by Microtiter dish biofilm formation assay. Antimicrobials activities of LAA and EGCG were determined by MIC and MBC assays using microdilution method.
Results: The highest antimicrobial resistance was detected against chloramphenicol (52.17%), followed by furazolidone (26.08%), and trimethoprim/sulfamethoxazole (21.73%). All isolates were sensitive to ciprofloxacin (100%), followed by gentamicin, imipenem (95.65%), and cefixime (91.30%). Most of the isolates (78.26%) were able to produce weak biofilm. LAA and EGCG inhibited the growth of S. Typhimurium at the MIC levels of 62.5~1000 and 1.56~400 µg/mL, respectively. The MBC value of LAA was >1000 µg/mL, while the corresponding value of EGCG varied from 100 to 800 µg/mL.
Conclusion: S. Typhimurium isolates revealed a multiple antibiotic resistance with biofilm production ability. As a result, EGCG, and to a lesser extent, LAA displayed potential antibacterial activity against S. Typhimurium and could be considered as useful compounds for the development of antibacterial agents against salmonellosis. -
Serological and molecular characterization of hepatitis B virus in asymptomatic blood donors in Iran
Background and Objectives: Hepatitis B virus (HBV) is an enveloped DNA virus belongs to Hepadnaviridea family. HBV infection is a serious global health problem, with 2 billion people infected worldwide, and 350 million suffering from chronic HBV infection. The aim of this study was to determine the serological pattern and molecular characterization of HBV diversity in asymptomatic blood donors in Iran alongside with the mutation status of HBV in relation to blood safety.
Materials and Methods: One hundred and sixty six samples from asymptomatic blood donors who were positive for hepatitis B surface antigen during 2012 to 2014 were selected. The serological and molecular markers were analyzed by screening HBsAb, HBcAb, HBeAg and HBeAb and HBV-DNA. For detection of HBV genotypes and possible mutations, HBV polymerase and pre core/core regions were sequenced.
Results: In term of serologic markers of HBV, 100% of asymptomatic blood donors were HBsAg positive and 97.6%, 92.2%, 5.4% and 2.4% of them were HBcAb, HBeAb, HBeAg and HBsAb positive respectively in asymptomatic blood donors. The maximum of samples viral load was 4.41 × 107 IU/ml for HBeAg positive blood donors. While the minimum and maximum of viral load in HBeAb positive samples was 1.21 × 102 IU/ml and 1 × 106 IU/ml respectively and the mean of viral load in HBeAb positive samples was 5.882 × 103 IU/ml. About 9.7% of HBeAb positive samples had a pre core mutation that is related to stopping the synthesis of HBeAg and only genotype D was prevalent in asymptomatic blood donors.
Conclusion: This study showed that from 166 samples most of them were in a chronic phase of HBV infection and just 5.4% of asymptomatic blood donors were in the acute phase or acute chronic phase of HBV infection. The major risk factor for HBV infection was a familial history of HBV. -
Background and Objectives: Different epidemiological studies have found that backyard chickens are a reservoir for poultry diseases. Most backyard chicken flocks have a poor level of biosecurity, which increases the risk of spread of diseases. In recent years, the number of backyard chickens has been on the rise in Iran. However, the health status of backyard flocks is still poorly documented. Thus, this study aimed at examining the seroprevalence of antibodies against infectious bronchitis virus (IBV) and molecular surveillance and genotyping of IBV among backyard chickens (without vaccination history) in Mazandaran province, North of Iran, 2014.
Materials and Methods: A total of 460 blood samples of unvaccinated backyard chickens in the mentioned area were tested for antibodies against IBV using commercial ELISA. Also, cecal tonsils were collected from 75 chickens in the same area. Real time RT-PCR (for detection) and RT-PCR and sequencing spike gene were performed.
Results: The seropositivity rate was 54.5%. In addition, we detected 793/B, Variant 2, and QX in the backyard flocks and performed phylogenetic studies on them. The phylogenetic study revealed that the detected genotypes had high homology with IBV strains that were infected broilers, pullets, and layers in Iran.
Conclusion: There is a need for continuous monitoring of IBV among avian species to complete the epidemiological map and work on the pathogenesis of Iranian IBV strains in Iranian backyard chickens.
