فهرست مطالب

  • Volume:5 Issue:1, 2019
  • تاریخ انتشار: 1397/10/11
  • تعداد عناوین: 7
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  • Leila Asadpour*, Saeed Veisi Pages 1-6
    Aims
    Methicillin resistant Staphylococcus aureus (MRSA) strains are a major contributor to the development of hospital- and community-acquired infections. The aim of this study was to evaluate the polymorphism of mecA gene, frequency of blaZ gene, and detection of mecA promoter mutations in clinical isolates of methicillin-resistant S. aureus strains.
    Materials & Methods
    Susceptibility of 85 S. aureus clinical strains to methicillin was evaluated using disc diffusion method. The polymorphism of mec-associated hypervariable region (HVR), presence of blaZ genes, and mutation in mecA promoter were determined by PCR and sequencing.
    Findings
    A total of 40 (47.1%) out of 85 S. aureus isolates were identified as methicillin resistant by phenotypic assays and PCR-based detection of mecA gene in MRSA strains. Seven different groups of repeats were found among these strains. Also, 39 MRSA strains harbored blaZ gene, and according to the sequence analysis of mecA promoter, R226S mutation was identified in 1 out of 10 isolates tested.
    Conclusion
    According to the obtained results, there was a high variation in the polymorphic region of mecA gene in clinical isolates of S. aureus. In addition, it was appeared that beta-lactamase enzyme production and antibiotic hydrolysis played an important role in the occurrence of resistance to beta-lactam antibiotics, and the effect of mutation in genes regulating mecA gene expression was negligible.
    Keywords: S. aureus, Methicillin resistance, Molecular typing
  • Simin Ariyarad, Seyedeh Elham Rezatofighi*, Hossein Motamedi Pages 7-14
    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.
    Keywords: Antibiotic resistance, Immune evasion cluster, Methicillin-resistant Staphylococcus aureus, Phage typing
  • Ali Shivaee, Maryam Mirshekar, Rokhsareh Mohammadzadeh, Shahla Shahbazi* Pages 15-23
    Aims
     Urinary tract infection (UTI) is one of the most common infections worldwide. The aim of this study was to investigate the association between ESBLs genes and quinolone resistance in Uropathogenic Escherichia coli isolated from patients with urinary tract infection .
    Materials & Methods
    A total of 150 E. coli isolates were collected from patients with urinary tract infection referring to Firouzgar Hospital in Tehran, Iran. Antimicrobial susceptibility of isolates were determined by disk diffusion method. Double-disk diffusion test was performed for phenotypic identification of extended-spectrum β-lactamase- (ESBL) producing isolates. PCR was used for the detection of ESBL-encoding genes in addition to quinolone (qnr) resistance genes.

    Findings
    There was a high resistance rate to most of the studied antimicrobial agents. Phenotypically, 75% of the isolates produced an ESBL enzyme and were resistant to different antimicrobial classes. In overall, 83% of the isolates carried ESBL genes, especially blaTEM and blaCTX-M  . 75% were positive for the quinolone resistance genes including qnrA , qnrB ,qnrS and qepA. These results indicate the association between the presence of various ESBLs genes and quinolone resistance in uropathogenic E. coli.

    Conclusion

    Resistance patterns show the increased incidence of antibacterial resistance in E. coli. Results of the current study indicate the high prevalence of ESBL-producing isolates and quinolone resistance genes. Simultaneous presence of genes responsible for antibacterial resistance has made the treatment of UTI more challenging than ever before.
    Keywords: Antimicrobial resistance, ESBL, Uropathogenic Escherichia coli, Quinolones
  • Aysan Karamghoshchi, Majid Akbari, Mohammad Arjomandzadegan*, Azam Ahmadi Pages 25-34
    Aims
    In recent years, Arcobacter has been isolated from various samples. It can cause diseases both in human and animal and be transmitted to human through water, food, and continuous contact with poultry meat. Therefore, people exposed to the contaminated meat such as chicken meat can be exposed to Arcobacter too and as a part of its transmission route. Thus, in this study, the frequency of Arcobacter species was evaluated in slaughterhouse workers and poultry meat sellers and healthy people not exposed to the poultry meat.
    Materials & Methods
    In the present study, 85 slaughterhouse workers and poultry meat sellers (exposed group) and 85 healthy people with other jobs (non-exposed group) were studied. By simple method, fecal samples were collected from Health Center of Arak city and tested by 4 methods including direct observation, culture, PCR, and m-PCR.
    Findings
    Campylobacter-like organisms were observed in 32 out of 85 samples from the exposed group and in 11 out of 85 samples from the non-exposed group by microscopic observation method. No sample was positive by culture method. However, by PCR method, the frequency of Arcobacter strains was 20 in the exposed group and 6 in the non-exposed group. According to the m-PCR results, among the 170 samples, 21 A. cryaerophilus and 14 A. butzleri strains were identified.
    Conclusion
    Chicken carcass are introduced as a main reservoir for Arcobacter; therefore, continuous contact with poultry meat can have a significant effect on the transmission of Arcobacter strains to individuals. Therefore, this study showed that the frequency of Arcobacter strains is more in exposed group than in non-exposed group.
    Keywords: Arcobacter, slaughterhouse workers, poultry meat sellers
  • Maryam Mohammadbeigi*, Samira Alimoradi, Seyyed Reza Hashemi, Maryam Meskini Pages 35-40
    Background
    With increasing infectious diseases as well as antimicrobial resistance in pathogens to existing drugs, researchers are now seeking for new drug candidates to be used as alternatives or complementary therapies. Maca is commonly used in traditional medication as herbal medicine.
    M
    aterials & Methods
    In this research, the antibacterial and antifungal activities of maca powder and ethanolic extract were evaluated against Staphylococcus aureus ATCC25923, Pseudomonas aeruginosa ATCC27853, Escherichia coli ATCC25922, Enterococcus faecalis ATCC29212, and Candida albicans ATCC10231 using Minimum Inhibitory Concentration (MIC), Minimum Bactericidal Concentration (MBC), and disc diffusion methods.
    Results
    The obtained results showed that there was no significant difference between the MIC and MBC of maca powder and extract against the reference and clinical strains. Also, no strain showed zone of inhibition at 30, 40, 50, and 60 µl of reference concentration.
    Conclusion
    According to the results obtained in this study, maca powder and extract had a poor inhibitory effect on bacterial and fungal growth.
    Keywords: L. meyenii, S. aureus, P. aeruginosa, E. coli, E. faecalis, C. albicans
  • Davood Azadi*, Tahereh Motalebirad, Fatemeh Rezaei, Hossein Ali Rahdar Pages 41-48
    Background
    Biodegradation is the metabolic ability of some microorganisms in degrading or transforming the organic and inorganic contaminants into less harmful and non-hazardous substances, which are then integrated into the natural biogeochemical cycles. Some microorganisms, mainly the members of family Actinomycetes, were found with the capability of transforming and degrading the polluting agents. In this study, three different Nocardia species with the ability to biodegrade organic and inorganic compounds were isolated from soil in Isfahan province.
    Materials & Methods
    The soil samples were collected from the hospital environments. Isolation process was done according to the standard methods. The identification and characterization of the isolates were based on the conventional and molecular methods, including direct sequence analysis of almost full length of 16S rRNA gene.
    Results
    Almost, the complete 16S rRNA gene sequences of the strains under study revealed that the isolates coded as NR6, NR17, NR18, NR25, NR26, and NR28 were the strains of N. cyriacigeorgica; NR7, NR34, and NR50 were the strains of N. coubleae; and NR4 was the strain of N. otitidiscaviarum. The relationship between the isolates under study and standard strain of Nocardia was supported by a phylogenetic tree of 16S rRNA gene.
    Conclusion
    In this study, 10 Nocardia strains with the capability of biotransforming polluting agents were isolated from the hospital environments. It was the first study conducted on the isolation and characterization of Nocardia strains, with the capability of degrading polluting agents, from Iranian hospitals. This study can be considered as a pioneer to develop a new insight about the study of microbial diversity in Iran using an applied approach to deal with environmental challenges.
    Keywords: Nocardia, 16SrRNA, Biodegradation, Hospitals, Environmental samples
  • Elahe Ghorbani Marghmaleki, Majid Akbari, Mohammad Arjomandzadegan*, Azam Ahmadi Pages 49-60
    Aim
    Thermophilic Campylobacter is the first cause of gastroenteritis infection in human. Nowadays, the prevalence of Campylobacter spp. is higher than other bacteria causing intestinal infection such as Salmonella and Shigella. This study was designed to compare the frequency of Campylobacter species in poultry slaughterhouse workers and poultry meat sellers (exposed group) and in healthy people (non-exposed group) in Arak city.
    Materials & Methods
    Among the 104 samples, 52 samples were collected from the slaughterhouse workers and poultry meat sellers, and 52 samples were collected from the control group. The stool samples were taken from the slaughterhouse workers, poultry meat seller, and healthy people who had not received antibiotics for the last two weeks. For enrichment, the samples were enriched in Preston broth medium at 37℃ for 48 hrs under the microaerophilic conditions. Then they were sub cultured using a passive filtration method on Brucella agar at 37℃ for 72 hrs under the microaerophilic conditions. Finally, the samples were directly tested using genus- and species specific PCR primers.
    Findings
    Of 52 samples collected from the slaughterhouse workers and poultry meat sellers, 11 (21.1%) samples were positive for the presence of Campylobacter spp. by PCR, and of 52 samples collected from the healthy people, 2 (3.8%) samples were reported as positive. The most frequent species isolated from the 2 groups were C.jejuni (53.84%) and C.coli (23.07%), respectively.
    Conclusion
    Chicken is identified as one of the important sources of Campylobacter infections in humans, which may contaminate poultry Slaughterhouse workers and chicken meat sellers, which in turn, they could potentially transmit Campylobacter strains to healthy people and chicken meat.
    Keywords: Campylobacter, Slaughterhouse, Poultry products