Mohsen Arzanlou - Academia.edu (original) (raw)

Papers by Mohsen Arzanlou

Journal of Water and Health

The prevalence, antibiotic resistance, and virulence characteristics of Staphylococci from hospit... more The prevalence, antibiotic resistance, and virulence characteristics of Staphylococci from hospitals, livestock, municipals, and poultry wastewaters were investigated in Ardabil, Iran. From 155 staphylococcal isolates, 44.5% were coagulase-positive Staphylococcus (CoPS) and 55.5% were coagulase-negative Staphylococcus (CoNS) spp. Both CoPS and CoNS species were mainly found in hospital and poultry wastewater samples. The most prominent CoPS and CoNS species were Staphylococcus aureus at 80% and Staphylococcus xylosus at 37%. Methicillin resistance was found in 2% of S. aureus isolates. Overall, 49.2% of CoPS and 47.6% of CoNS isolates exhibited multidrug resistance phenotypes. CoPS isolates were the most resistant to penicillin (89%) and erythromycin (62%) and CoNS isolates exhibited the highest resistance to erythromycin (55%) and tetracycline (49%). Inducible clindamycin resistance was detected in 11% of S. aureus isolates. The ermC and aac genes were detected as the most common m...

Jundishapur Journal of Microbiology

Background: Asymptomatic carriage of Staphylococcus aureus can lead to endogenous infections and ... more Background: Asymptomatic carriage of Staphylococcus aureus can lead to endogenous infections and cross-transmission to other individuals. Objectives: The prevalence, molecular epidemiology, antibiotic resistance, and risk factors for nasal carriage of methicillin-resistant Staphylococcus aureus (MRSA) were studied in school children in Ardabil, Iran. Methods: Totally, 510 nasal samples were collected during 2017. Isolates were identified and subjected to antimicrobial susceptibility testing, identification of oxacillin resistance, and molecular typing. Results: Totally, 13.5% of volunteers were positive for methicillin-susceptible Staphylococcus aureus (MSSA) and 17.5% colonized with mecA positive S. aureus strains, including 6.07% oxacillin-resistant MRSA (OR-MRSA) and 11.56% oxacillin-susceptible MRSA (OS-MRSA). Excluding β-lactam antibiotics, high resistance rate was observed for erythromycin (71%), tetracycline (25.8%), clindamycin (35%) in our isolates. Surprisingly, 11% of the...

Iranian Journal of Microbiology

Background and Objectives: Nowadays, high-level aminoglycosides and ampicillin resistant Enteroco... more Background and Objectives: Nowadays, high-level aminoglycosides and ampicillin resistant Enterococcus species are among the most common causes of nosocomial infections. The present study was conducted to determine the prevalence of high-level resistance to aminoglycosides and ampicillin among clinical isolates of Enterococcus species in Ardabil, Iran. Materials and Methods: In this cross–sectional study, a total of 111 Enterococcus species were collected from different clinical specimens between 2013 and 2015. Enterococcus species were identified using standard phenotypic and genotypic methods. BHI agar screen and agar dilution methods were used for detection of high-level gentamicin and streptomycin resistance (HLGR and HLSR) and minimal inhibitory concentration (MIC) of ampicillin, respectively. Results: Of 111 clinical isolates, 59 (53.2%) and 25 (22.5%) isolates were E. faecalis and E. faecium, respectively, based on the PCR results. Totally, 60.3% and 56.7% of isolates were HLG...

Essays In Biochemistry

Gram-negative bacteria are responsible for a large proportion of antimicrobial-resistant infectio... more Gram-negative bacteria are responsible for a large proportion of antimicrobial-resistant infections in humans and animals. Among this class of bacteria are also some of the most successful environmental organisms. Part of this success is their adaptability to a variety of different niches, their intrinsic resistance to antimicrobial drugs and their ability to rapidly acquire resistance mechanisms. These mechanisms of resistance are not exclusive and the interplay of several mechanisms causes high levels of resistance. In this review, we explore the molecular mechanisms underlying resistance in Gram-negative organisms and how these different mechanisms enable them to survive many different stress conditions.

Microbial pathogenesis, 2016

Streptococcal pyrogenic exotoxin B (SpeB) is an important virulence factor of group A streptococc... more Streptococcal pyrogenic exotoxin B (SpeB) is an important virulence factor of group A streptococci (GAS) and inactivation of SpeB results in the significantly decreased virulence of the bacterium. The protein is secreted as an inactive zymogen of 40 KDa (SpeBz) and undergoes proteolytic truncation to result in a 28 KDa mature active protease (SpeBm). In this study the effect of allicin on the proteolytic activity of SpeBm was evaluated using azocasein assay. Allicin neutralized the SpeBm proteolytic activity in a concentration dependent manner (IC50 = 15.71 ± 0.45 μg/ml). The loss of activity was completely reversed by subsequent treatment with a reducing agent, dithiothreitol (DTT; 10 mM final concentration), suggesting that allicin likely inhibits the SpeBm by forming a disulfide linkage with an active thiol group in its active site. This mechanism of action was further confirmed with the fact that DTT did not reverse the SpeBm activity in the presence of E-64, a cysteine protease...

Jundishapur Journal of Natural Pharmaceutical Products, 2015

Iranian Journal of Microbiology, Sep 1, 2012

Background and Objectives: Group B Streptococci (GBS) is a major cause of neonatal and maternal i... more Background and Objectives: Group B Streptococci (GBS) is a major cause of neonatal and maternal infections. The aim of this study was to determine the serotype distribution and antibiotic resistance profile of GBS strains isolated from pregnant women in Ardabil. Materials and Methods: Antibiotic resistance of 56 GBS isolates was investigated using E-test strips and disk-diffusion method. Serotyping was performed using capsular antiserum.

Iranian Journal of Microbiology, Jun 1, 2014

Introduction: Brucellosis is a worldwide zoonosis and is endemic in all parts of the Iran. The de... more Introduction: Brucellosis is a worldwide zoonosis and is endemic in all parts of the Iran. The development of new diagnostic techniques that facilitate rapid detection and identification of brucellae and minimize the risk of laboratory infection is of great practical importance. The aim of this study was to evaluate two different PCR methods for the detection of Brucella spp. DNA in human serum samples. Methods: Serial dilutions of purified DNA were made. The two pairs of primers have chosen amplified regions of two different Brucella genes. All amplifications were performed in a total volume of 25 μl, containing serial dilutions of Brucella DNA and positive and negative controls. The negative control contained sterile water instead of DNA template. As positive controls, DNA isolated from Brucella spp was used. Results: The two PCR assays had excellent sensitivity for detection of Brucella spp DNA in serum samples. The two primers assayed did not show a difference in sensitivity for...

FEMS microbiology letters, Jan 2, 2015

Several virulence factors contribute to the pathogenesis of Proteus mirabilis. This study determi... more Several virulence factors contribute to the pathogenesis of Proteus mirabilis. This study determined the inhibitory effects of allicin on urease, hemolysin, and biofilm of P. mirabilis ATCC 12453 and its antimicrobial activity against 20 clinical isolates of P. mirabilis. Allicin did not inhibit hemolysin, whereas it did inhibit relative urease activity in both prelysed (half-maximum inhibitory concentration, IC50 = 4.15μg) and intact cells (IC50 = 21μg) in a concentration-dependent manner. Allicin at sub-MIC concentrations (2-32μg mL(-1)) showed no significant effects on the growth of the bacteria (P > 0.05), but it reduced biofilm development in a concentration-dependent manner (P < 0.001). A higher concentration of allicin was needed to inhibit the established biofilms. Using the microdilution technique, the MIC90 and MBC90 values of allicin against P. mirabilis isolates were determined to be 128 μg mL(-1)and 512 μg mL(-1), respectively. The results suggest that allicin cou...

Iranian journal of microbiology, 2012

Group B Streptococci (GBS) is a major cause of neonatal and maternal infections. The aim of this ... more Group B Streptococci (GBS) is a major cause of neonatal and maternal infections. The aim of this study was to determine the serotype distribution and antibiotic resistance profile of GBS strains isolated from pregnant women in Ardabil. Antibiotic resistance of 56 GBS isolates was investigated using E-test strips and disk-diffusion method. Serotyping was performed using capsular antiserum. The results of MIC tests showed all isolates were susceptible to ampicillin, vancomycin and penicillin. One isolate (1.7%) showed reduced susceptibility pattern to penicillin (MIC; 0.25 µg/ml). There were 3 (5.3%) isolates semi-sensitive (0.25-1 µg/ml) to erythromycin (2; 0.5 µg/ml and 1; 0.38 µg/ml) and 2 (3.5%) isolates to clindamycin (1; 0.5 µg/ml, 1; 0.38 µg/ml). Additionally, 2 (3.5%) isolates were resistant to clindamycin (1; 16 µg/ml, 1; 2 µg/ml). According to the disk diffusion test, 47 (83.9%), 8 (14.2%) and 7 (12.5%) isolates were resistant to Co-trimoxazole, ciprofloxacin and ceftriaxone...

<span style="font-size: 13.5pt; line-height: 115%; font-family: 'times new roman', serif;... more Background & Objective: P.mirabilis is one of the common agents involved in urinary tract infections, especially in patients undergoing urinary catheterization. P.mirabilis is capable of living as biofilm and/or planktonic forms. Biofilm plays a significant role in P.mirabilis infections. Cells in the biofilm show higher degree of resistance to antimicrobial therapy and host immune responses compared with planktonic cells. So inhibition of biofilm formation could help the body's immune system to combat the bacteria and improve the clinical outcomes for antimicrobial therapy. This study was aimed to investigate the inhibitory effect of allicin on biofilm formation by P.mirabilis. Material&Methods: This study was carried out using a P. mirabilis ATCC12453. Allicin was purified using semi preparative HPLC procedure. MIC of allicin was determined by microdilution method using serial dilutions of aqueous allicin solution (4-512 µg/ml) in Mueller-Hinton broth. Biofilm inhibition was assayed using Microtiter plate method in the presence of sub-MIC concentrations ( 4µg-32µg) of allicin. The plates were incubated for 18 hours at 37 ºC. Bacterial biofilms were stained with 0.2%safranin. Dye was solubilized using alcohol-Aceton as solvent and the optical density (OD) was measured at 492 nm wavelength. The extent of biofilm formation was determined (OD of sample well/OD of control well*100). Each assay was performed in triplicate and repeated two times.Results: The allicin MIC was 64 µg/ml for P. mirabilis ATCC12453. The results indicated that allicin at concentrations of 16 and 32µg/ml significantly diminished biofilm formation (P˂0.01). This concentration did not have significant influence on bacterial growth rate. Conclution: The results showed that allicin can inhibit the biofilm formation by P.mirabilis. Allicin, Biofilm inhibition, P. mirabilis. Presentation: Poster