pISSN: 2251-8649
eISSN: 2322-2581
Editor-in-Chief:
Dr. Mohammad Reza Pourshafie
Vol 4 No 1-2 (2015)
Original Articles
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Introduction: One of the most important agents in hospital-acquired infections is
Staphylococcus aureus. Treatment of methicillin-resistant S. aureus (MRSA) infections with
decreased susceptibility to vancomycin has recently been more difficult. The aim of this study
was to evaluate the possible presence of vancomycin intermediate S. aureus (VISA) and
vancomycin- resistant S. aureus (VRSA) and also to determine the frequency of MRSA in
clinical specimens.
Methods: In this study, 195 S. aureus isolates were collected from the patients were examined.
All of the isolates were identified using standard biochemical tests. Susceptibility of S. aureus
isolates against 10 antibiotics was detected by disk diffusion method and was followed by E-test
and vancomycin screen agar methods. Minimum inhibitory concentration (MIC) of vancomycin
was determined according to the CLSI guidelines. Also, detection of mecA gene was performed
by PCR and finally, the results were compared.
Results: All of the isolates were susceptible to vancomycin (i.e. MIC range of vancomycin was
between 0.25-2 µg/ml). Out of 195 S. aureus isolates, 99 isolates (50.8%) were resistant to
methicillin, and mecA gene was detected in 96 isolates. These results also showed that the
highest and lowest resistance rate of isolates was to penicillin (96.9%) and chloramphenicol
(0%), respectively.
Conclusion: Our findings showed that vancomycin can still be used as a valuable drug for
treatment of S. aureus infections in our region. However, periodic evaluation of vancomycin
MIC of S. aureus isolates is critical for monitoring MRSA and preventing the spread of VISA or
VRSA among patients. -
Introduction: Nocardia is saprophytic soil bacterium of the actinomycetes families. Nocardia
has high diversity of species and due to species diversity of Nocardia, phenotypic tests are
essential for early identification of Nocardia species.
Methods: 155 soil samples from different regions of North Khorasan province in Iran were
collected, including: urban and rural areas. Isolation of Nocardia was performed by paraffin
baiting Technique. Identification of Nocardia species was performed by phenotypic methods
that are including: hydrolysis of the amino acids, acid production of carbohydrates and, growth
at 35° C and 45°C.
Results: 11 Nocardia species (7%) were identified . These bacteria were related to the gardens,
the sands soils, and soil of town square. No growth was observed at 45°C. As the result, our
isolates were identified as Nocardia asteroides complex.
Conclusion: Isolation and identification of Nocardia spp. from soil of different regions in North
Khorasan province in Iran can help to enhance our understanding of epidemiological and
ecological of the pathogenic Nocardia species. -
Introduction: Streptococcus pneumoniae cause morbidity and mortality in infants and younger
children. Because of high prevalence of penicillin resistance, rapid and reliable diagnostic
techniques for penicillin non-susceptible S. pneumoniae (PNSSP) are important for prevention
and treatment. We investigated the association of the restriction length polymorphism (RFLP)
patterns for pbp2b to distinguish between penicillin susceptible and resistant S. pneumoniae
isolates.
Methods: In this study, a total of 70 pneumococcal isolates were collected from different clinical
sources. MIC of these isolates was determined and pbp2b gene was amplified by PCR and they
were digested by HaeІІІ enzyme.
Results: Of the 70 isolates, 86% (60) and 14% (10) pneumococcal isolates were found to be
PNSSP (penicillin intermediate S. pneumoniae (PISP) and penicillin resistant S. pneumoniae
(PRSP)) and penicillin susceptible S. pneumoniae (PSSP). In addition, 10 RFLP patterns (A-J)
which were based on the HaeІІІ digestion of pbp2b gene were observed. All PSSP isolates
showed that they belonged to pattern D, whereas, all PNSSP showed 10 different patterns.
Conclusion: In general, the present study suggests that RFLP can be a powerful tool in
differentiation between the penicillin resistant and susceptible strains. -
Introduction: Antibiotics have the potential to adversely affect the microbial community. For
anaerobic digestion, a sufficient methanogenic population needs to be preserved in the system.
The main aim of this study was determination of inhibitory concentration of oxytetracycline on
methanogenic bacteria.
Methods: A 120 mL jacketed bioreactor with a 90 mL working volume was inoculated granular
sludge from an anaerobic digester, substrate and different concentration of oxytetracycline with
10 days cycles and intermittent mixing. The reactor was operated at 35 ± 2 ° C. The inhibitory
effect of antibiotic was evaluated by monitoring biogas production.
Results: Based on the findings from each batch, complete inhibitory concentration of oxy
tetracycline was in concentration of 800 mg L-1. Significant relation was seen between
inoculated antibiotic concentrations and methane production (r=-0.86).
Conclusion: The addition of antibiotics to the biomass affected the utilization of fatty acids,
resulting in unfavorable effects on methanogenesis. Thus, overusing of antibiotics can adverse
effects of intestinal flora. -
Introduction: Biofilm producing Staphylococcus aureus is known as one of the major
causative agents of infections, failure of implanted devices and persistent infection
among hospitalized patients. The aim of the present study was to determine the
frequency of biofilm producing S. aureus isolates amongst the clinical specimens.
Methods: This cross-sectional study was conducted during 2012 to 2013 in two
teaching hospitals in Shiraz, southwest of Iran. Totally, 345 S. aureus isolates from
various clinical specimens were included. Biofilm producing isolates were
phenotypically detected using Congo Red Agar (CRA) and genotypically by PCR
assay for the icaA and icaD genes.
Results: Of the 345 S. aureus isolates, 42.3% were methicillin-resistant S. aureus
(MRSA) and subsequently 57.7% were methicillin susceptible isolates. The results of
CRA plates showed that 77 (52.7%) and 74 (37.2%) of MRSA and MSSA were
biofilm producing isolates. The frequency of icaA/D genes among MRSA and MSSA
isolates was 127 (87%) and 167 (83.9%), respectively.
Conclusion: Such a high rate of icaA/D harboring S. aureus among clinical isolates
suggest the risk for establishing persistent infections in the hospital settings. -
Introduction: ESBLs are a B -lactamases which had ability to hydrolyse third-generation
cephalosporins and aztreonam. ESBLs producer bacteria are resistant to a wide variety of
antimicrobials and they made a serious global health concern for treatment strategies. So, aim of
this study as to molecular detection of ESBLs in bacteria isolated from blood cultures in
hospitals from Kurdistan Province, Iran.
Methods: Biochemical test, antimicrobial susceptibility test by disc method, ESBL detection by
NCCLs Phenotypic and PCR method for ESBL detection were applied. Results were analyzed
by using SPSS 11.5 (p < 0.05).
Results: 96 S. epidermidis isolated from blood cultures, E. coli, Enterobacter spp., Klebsiella
spp., P. aeruginosa, Salmonella spp., C. freundii, S. maltophilia, also S. aureus, and
S.epidermis. Maximum resistance was 75% for CP and minimum resistance was 25% for GM.
Of the 96 isolates, 20 (20.83%) produced ESBLs. Also 11.46%, 20.83%, 12.5%, 9.38% and
2.08% were positive for TEM, CTX-M, SHV, OXA-1 and OXA-2 ensymes, respectively.
Conclusion: Inappropriate therapy for infections with ESBL producers is cause of prolongs
hospital stay and mortality. So, more research on drug resistance with ESBL is necessary. -
Inducible Clindamycin Resistant Staphylococcus aureus in Iran: A Systematic Review and Meta-AnalysisIntroduction: Staphylococcus aureus is a prominent human pathogen. One of the drugs used in
the treatment of staphylococcal infections (particularly infections of skin and soft tissue), is
clindamycin. Resistance to clindamycin includes two types: inducible and constitutive. Routine
laboratory methods of antibiotic susceptibility testing cannot detect the inducible type and Dtest is required for its detection. The purpose of this systematic review was to determine the
relative prevalence of this type of resistance in Iran.
Methods: Search terms "inducible clindamycin resistant", "D-test", "Staphylococcus aureus"
and "Iran" were used to find relevant articles in PubMed, Google Scholar and two Persian
search engines. Also, the abstracts of the recent national microbiology congresses were checked.
All studies used D-test to find iMLSB (inducible macrolide, lincosamide and streptograminB
resistance) phenotype among clinical isolates (not nasal swabs) of S. aureus, were included. In
order to perform meta-analysis, we used “comprehensive meta-analysis” software (ver. 2).
Results: In total, 9 articles and 8 abstracts related to the topic of the study were found. Random
effects meta-analyses showed a pooled estimate for percentage of iMLSB phenotype among
2683 samples of S. aureus was about 10% (95% confidence interval: 0.07-0.12). Using the fixed
effect model, the odds of positive iMLSB in methicillin-resistant S. aureus was about 5 times
more likely to occur in comparison with methicillin-susceptible S. aureus (95% CI: 3.49 to
7.76).
Conclusion: Fortunately, the relative frequency of inducible resistance to clindamycin in our
country is relatively low. However, we believe that D-test should be performed for all
erythromicin-resistant isolates in order to identify inducible resistance to clindamycin.
Moreover, reevaluation of inducible resistance to clindamycin in forthcoming years is highly
recommended. -
Introduction: Due to more resistance of pathogenic bacteria to new and current
antibiotics researchers are looking to find the agents of herbal with antimicrobial
activities in order to replace chemical drugs.
Methods: The herbal extract of Withani somnifera was done by using a rotary vacuum,
20 strains of Pseudomonas aeruginosa were isolated from urinary infections hospitalized
patients in city of Zabol hospital. The MIC Withani somnifera were determined by
dilution method in various concentrations. Sensitivity of strains to multiple antibiotics
was evaluated by standard disk diffusion Kirby-Bauer.
Results: The result showed that P. aeruginosa were resistance to 4 of the agents
including ampicillin (85%), nitrofurantoin (65%), nalidixic acid (65%), ciprofloxacin
(15%) and for 5 strains of Pseudomonas showed MIC with activity of 100 ppm.
Conclusion: This study has suggested the effect of winter cherry extract on P.
aeruginosa in the in vitro assay. It s effectiveness of on in vivo system can be examined
in future.
