احمد مصدق

Bacteriocins are peptides with antimicrobial properties. They are ribosomally synthesized and produced by both gram-positive and gram-negative bacteria. The bacteriocins produced by Escherichia coli are called colicins. Colicins in commensal bacteria inhibit the growth of pathogenic bacteria and in pathogen strains, they increase bacterial virulence. The aim of this study was to evaluate the frequency of col V and col Ia genes in Escherichia coli specimens isolated from patients with urinary tract infections in Yazd City, Iran.

In this descriptive cross-sectional study, 160 Escherichia coli samples were isolated from urine specimens and identified by common biochemical tests. The amplification of col V and col Ia genes was performed by PCR method using specific primers and after sequencing, the results were analyzed using SPSS version 16 software.

In this study, out of 160 Escherichia coli isolates examined, calicin gene was detected in 26.9% of the isolates. The frequency of col Ia gene was 24.4% and the frequency of col V gene was 10.6%. Furthermore, in 8.12% of isolates, both genes were identified together. The frequency of isolates containing only col Ia gene was 16.2% and isolates containing only col V gene was 2.5%.

In this study, isolates with col Ia gene showed high frequency. Most strains with col V gene also had col Ia gene. Therefore, the col V gene is often observed together with the col Ia gene.

E. coli is the predominant causes of urinary tract infection. Several virulence factors for bacterial infections in the urinary tract are required. In this study, we have considered several virulence factors in strains isolated from the patients with UTI in Yazd.

In this cross-sectional study in 1394-1395, 146 strains isolated were collected from the patients with urinary tract infection. After confirmation by phenotypic and genotype methods, frequency of gene fimH, pap C, aer was evaluated using specific primers by PCR method. The pattern of antibiotic resistance of isolates was determined by disk diffusion method.

In the present study, the prevalence of virulence genes was fimH (87%), aer (85.6%) and papC (9.6%). Among 146 E. coli isolates, resistance rate for various antibiotics were as follows: 57.2% to Cotrimoxazole, 54.8% to Nalidixic acid, 45.9% to Cefazolin, 40.4% to Cefixime, 42.5% to Cefalotin, 41.8% to Cefalexin, 31.5% to Norfloxacin, 30.1% to Ofloxacin, 28.3% to Ciprofloxacin, 24% to Gentamicin, 19.9% to Amikacin, 1.4% to Nitrofurantoin, and 1.4% to  phosphomycin. The results showed that the most and less frequent resistant was seen in Cotrimoxazole and Nitrofurantoin, phosphomycin, respectively.

In this study, the frequency of fimH gene was higher than other genes. In addition, according to the pattern of antibiotic resistance nitrofurantoin and phosphomycin are suitable medicines for the treatment of patients in our region.

Polymerization shrinkage causes a gap between the composite resin and the tooth edge which leads to bacterial invasion, secondary caries, recurrent caries, and the final failure of restoration. It seems that the addition of nanoparticles to composites can be effective in the reduction of the number and function of microorganisms. The aim of the present study was to compare the antibacterial properties of composite resins containing zinc-oxide with copper-oxide nanoparticles against Streptococcus mutans.

A number of 490 discoid tablets containing 0.05%,0.5%, 0.1% nano-copper and nano zinc-oxide particles were prepared from composite resin GC (n=70). Diluted solutions of Streptococcus mutans (ATCC 35668) were prepared and 1 mL of bacterial species was placed on the discs. The discs were transferred to liquid culture media and were incubated at 37℃ for 8 hr. Thereafter, 1 mm of serum was cultured at 37° C for 24 hours on a blood agar containing sheep blood and the total number of bacteria was obtained by colony counting of all bacteria detected on each disk. The data were analyzed in SPSS software (version 17) using Kolmogorov-Smirnov test (k-s), Kruskal-Wallis, and Dunn's test. The significance level was considered as α = 0.5.

Based on the obtained results, the composites containing 0.1% and 0.5% Nano zinc oxide particles and copper oxide nanoparticles significantly decreased the number of bacteria in 15 and 30 days, as compared to the control group (P-value=0.001). Nonetheless, other groups did not demonstrate any significant difference with the control group (P-value=1).

Composite resins containing 0.5% zinc oxide nanoparticles demonstrated the highest antibacterial activity against Streptococcus mutans. On the other hand, both nano-copper and zinc-oxide particles revealed the least antimicrobial activity in the concentration of 0.05%.

Background and

Alzheimer's disease (AD) is a neurodegenerative disorder which is an ordinary type of dementia in the elderly. It impairs memory and cognitive ability. Different kinds of treatment have been presented to cure AD or reduce its progression, most of which are based on inhibition of acetylcholinesterase enzyme. According to traditional Persian medicine, the bay laurel fruit has been applied for different medical purposes such as improving mind and memory function. The aim of the presented study was to evaluate the acetylcholinesterase inhibitory activity of fixed and essential oil of Laurus nobilis L. fruit.
Methods and Materials: Dried fruit of Laurus nobilis L. was subjected to hydro distillation for obtaining the essential oil, then the fixed oil of fruit was extracted by a Soxhlet apparatus (n-hexane as a solvent). Ellman method was employed to evaluate the acetylcholinesterase inhibitory activity of bay laurel fruit.

Both fixed and essential oil exhibited acetylcholinesterase inhibitory activity which the percentage of inhibition for fixed oil (1.35 mg.mL-1) and essential oil (1.8 μg.mL-1) was 34.33 ±2.4 and 50, respectively.

According to the results obtained from the present study, the effect of bay laurel on mind and memory can be relevant to its acetylcholinesterase inhibitory activity.

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. The aim of the present study was to determine the antimicrobial susceptibility profile and frequency of ESBL genes in clinical isolates of A. baumannii in hospitals in Kerman, Iran.
In this cross-sectional study 102 isolates of Acinetobacter species were collected from clinical specimens, including, respiratory secretions, urine, blood culture and body fluid. For confirming A. baumannii Polymerase chain reaction (PCR) was used to identify blaOXA-51 gene. Antimicrobial susceptibility test was performed using the disk diffusion method. PCR technique was carried out for the detection of blaCTX-M, blaSHV, blaTEM, blaPER and blaVEB genes.
FINDINGS: blaOXA-51 gene was detected in 95 (93/1%) isolates. All of the isolates were resistant to cefepime and cefotaxime. Almost all of them were resistant to imipenem, meropenem, gentamicin, amikacin, aztreonam, ciprofloxacin, ceftazidim, levofloxacin, tetracycline and piperacillin-tazobactam. The rates of susceptibility to polymyxin-B and tigecycline were 61/1% and 23/2% respectively. The frequency of, blaSHV, blaTEM, blaCTX-M and blaVEB genes were 44 (46.3%), 30 (31.6%), 30 (31.6%), and 13 (13.7%) respectively. None of the isolates were carried blaPER gene.
because of the high rate of ESBLs producing A. baumannii isolates detected in this study, effective infection control strategy should be performed

Pseudomonas aeruginosa is one of the most important factors for nosocomial infections with percentage of resistance to the drug, particularly in the burn wounds. One of the mechanisms of resistance in these bacteria is chromosomal mutation in the quinolone-resistance-determining region (QRDR) of chromosome gene. The aim of this study was to evaluate gyrA and parC gene mutation in Pseudomonas aeruginosa isolates from burn wound infections resistant to ciprofloxacin.
50 clinical Pseudomonas aeruginosa isolates were identified from patients admitted to burn hospital. Minimum inhibitory concentrations (MICs) of ciprofloxacin were evaluated by E-test method and polymerase chain reaction-sequencing (PCR-sequencing) method was carried out to assess the gyrA and parC mutations in ciprofloxacin-resistant isolates.
Findings: From 50 isolates, 62% were resistant to ciprofloxacin. Mutations were detected in all (100%) and 41 isolates (82%) in gyrA and parC genes, respectively. The most frequent mutations were observed in gyrA gene conversion (T83I) and parC (S87L). No mutation was found in sensitive isolates.
Results indicate that mutations in the quinolone-resistance-determining-region are the major mechanisms for ciprofloxacin resistance in clinical isolates of Pseudomonas aeruginosa. Considering the prevalence of these genes, these mutations play a major role in the development of resistance.

Multidrug resistance is emerging among gram negative bacteria that cause hospital infections or community acquired around the world. The aims of this study were (1) determination of antibiotic susceptibility profile of Enterobacter spp. isolates recovered from blood, (2) phenotypic identification of ESBL and AmpC-producing isolates, (3) identify MDR strains, and (4) identification isolates harboring blaSHV gene using PCR method.
In this cross-sectional study, 90 isolates of Enterobacter spp. isolated from blood stream infection from patients admitted to hospitals in Shiraz using BACTEC 9240 automated system during 10 years (2004-2014). The isolates again were identified by using embedded biochemical tests in the Enterobacteriaceae API-20E diagnostic system. According to proposed protocol by CLSI (2014), standard disc diffusion method and DDST phenotypic test were used for antibiotic susceptibility test, and identification of ESBL-producing strains, respectively. PCR molecular method was used to identify blaSHV gene in strains.
In this study, as observed, meropenem (98.9%), imipenem (95.6%) and colistin (93.3%) were the most effective antibiotics against isolates. Isolates showed the best response to ceftazidime (47.8%) and ceftriaxone (42.2%), respectively, among the third generation of cephalosporins which were investigated. Results showed that 11.1% of isolates were MDR. 15.5% isolates were positive ESBL and positive AmpC, simultaneously. As revealed, 11.1% of isolates were MDR. The results of PCR to search for blaSHV gene in Enterobacter isolates revealed that 7.8% of the strains harboring this gene.
Results showed that the resistance of Enterobacter isolates to the third generation of cephalosporins has become a national health-threatening problem. Epidemiologic studies are crucial in order to presentation of comprehensive national program to preventing emergence and dissemination of resistant bacteria in the country. We believe that carbapenems should be used for the treatment of strains resistant to other antibiotics in order to preservation of carbapenems as strategies for the treatment of Enterobacter spp.

Klebsiella pneumoniae is an opportunistic pathogen that causes urinary tract Infection (UTI), intra-abdominal infection and pneumonia in patients with weakened immune systems or underlying diseases. Several studies have shown that the indiscriminate and irregular use of antibiotics can cause antibiotic resistance. Antimicrobial resistance has been introduced as one of the most important global health risks by the World Health Organization (WHO). Due to the increasing resistance of pathogens to antibiotics, antibiotic resistance patterns of Klebsiella pneumoniae strains isolated from urine samples have been investigated.
In this descriptive-sectional study, 130 isolates of Klebsiella pneumoniae were collected from hospitalized patients with urinary tract infections and identified by biochemical tests. Antimicrobial susceptibility test was evaluated by standard disk diffusion method (Kirby-Bauer) that has been recommended by the CLSI.
From 130 strains of Klebsiella pneumoniae, 72 strains (55.4%) were isolated from female patients. The results showed that the highest rate of resistance was belonged to amoxicillin (100%) and cefotaxime (41.5%) respectively and the lowest rate of resistance was for meropenem (3.8%) and ertapenem (3.8%).
The results of this study and other similar studies show that resistance to different antibiotics have been acquired, so it is recommended that antimicrobial susceptibility tests should be performed before treatment and the results are reported to the clinicians and infection control committees.

The major mechanisms which contribute to the spread of shigellosis are antibiotic resistance and transmission from person to person. The main purpose of this study was determination of antibiotic susceptibilities and survey of the prevalence of integrons class I and II genes in Shigella species isolated from patients in Kerman hospitals In this cross-sectional study, 38 different Shigella species were collected from Kerman hospitals and were typed by serologically slide agglutination with specific antiesera. Antibiotic resistance patterns of shigella species were also evaluated by disk diffusion method. Detection of intI and intII genes was carried out by Polymerized Chain Reaction (PCR). Data analysis was done by Fisher,s exact test. In the current study 21 (55.2%) S.flexneri, 14 (36.8%) S.sonnei, 3(7.8%) S.boydii and no S.dysenteriae were detected by serologically slide agglutination and the majority of strains were resistant to ampicillin but were sensitive to ciprofloxacin. Of all 38 Shigella isolates, 21 (55.2%) species were demonstrated intI gene but 32 (84.2%) species presented intII gene after performing PCR. According to high frequency of integrons and high resistance to antibiotics in shigella isolates, following health recommendations and prescribing correct antibiotics can prevent the extension of the diorrhetic disease resulted from shigella.

Streptococcus agalactiae is the major cause of meningitides and septicemia in infants and also intrauterine infection and preterm labor in pregnant women. This study aimed to determine the prevalence of group B streptococci (GBS) colonization in rectovaginal region of 15 to 40 years, pregnant women. Recto-vaginal swab samples from 250 pregnant women referred to health centers in the city of Yazd, Iran, 2002, were taken. The specimens were cultured on sheep blood agar and the presence of GBS was identified with catalase-negative, hipporte hydrolysis, CAMP (Christie Atkins Munch-Petersen) test, and Gram staining. Results were confirmed by polymerase chain reaction (PCR) molecular methods for the amplification of cpsH capsular gene. Out of 250 samples, 49 (19.6%) were identified as Streptococcus agalactiae. All 49 samples were PCR positive with cpsH gene fragment with a 550 bp fragment in length that were assessed with 1% gel agarose electrophoresis. The most prevalence was identified among women with 20-25 years old and the least one among 15-20. Statistics of GBS prevalence varies in different regions which could be due to various factors such as age, sex, culture method and the inherent differences in study populations and increased use of antibiotics in some populations. Due to high prevalence of GBS in Yazd, Iran, appropriate screen/control programs would be necessary to prevent the damages in infants and mothers.

Background and objectivesABO blood group antigens with carbohydrate molecules are found on the surface of uroepithelial cells, which influence human susceptibility to infectious diseases. The present study tries to determine the relation between these antigens and the type of the urinary tract pathogens. Materials and MethodsIn this descriptive study, 250 patients whose urinary tract infection had been confirmed by pyoria and positive urine culture were studied. Sampling method was continued until at least 30 patients from different blood groups were involved. A questionnaire addressing age, sex, blood group type, and type of UTI pathogen was filled out for each patient. Data were analyzed by SPSS 13, chi-sqaure, and fisher test. ResultsThe results showed E.coli as the most prevalent type of the urinary tract pathogen in B and O blood groups with the rates of 72.7% (CI95%= 54.08 - 91.32) and 52.3% (CI95% = 41.54 - 63.06), respectively. Staphylococcus saprophyticus was also the most prevalent pathogen in blood groups A and AB with the rates of 43% (CI95%= 30.1 - 50.9) and 39% (CI95%= 16.48 - 61.52), respectively. The correlation between urinary tract pathogens and blood groups was significant (p<0.05). However, urinary tract pathogens had no significant correlation with sex and age. ConclusionsE.Coli is the most common known cause of UTI; however, it is Staphylococcus saprophyticus being the most common pathogen in blood groups A and AB.