فهرست مطالب ali jazayeri moghadas

Urinary tract infection (UTI) is one of the most common infections and Enterobacteriaceae members are the most common bacterial agent of this infection. Antibiotic susceptibility pattern identification is necessary for complete treatment. In this way, this study was accomplished to compare the enterobacteriaceae antibiotic resistance pattern of UTI patients. This study including two groups of 78 patients as outpatients and admitted ones. UTI was diagnosed by urine culture and colony count. Antibiotic susceptibility test performed according to CLSI guidelines. E. coli was recognized as the most frequent bacterial agent in both outpatients (66.7%) and admitted (82.1%) groups, while klebsiella spp. caused UTI in 16.7% of admitted patients and 32.1% of outpatients. The most antibiotic resistance was observed to Cefazolin (85.9%) and Nalidixic acid (78.1%) in outpatients and admitted respectively. Resistance to cefazolin in outpatients was significantly more than admitted patients, while resistance to amikacin, ciprofloxacin, nalidixic acid, ceftriaxone, cefotaxime, and gentamycin in admitted patients was significantly more than outpatients. Conspiciously, the resistance rate to ciprofloxacin, nalidixic and cefixime significantly increased in comparison with a similar study in Semnan (Ian), 2000.  The differences in antibiotic resistance pattern must be notified in outpatients and admitted patients, in order to better antibiotic prescription

Quorum-sensing systems are considered as important mechanisms for pathogenesis and bacterial communication. The accessory gene regulator (agr) is one of the quorum-sensing systems in staphylococci, which is generally conserved. It is believed that there is a correlation between agr groups and infection. Multiple-locus VNTR analysis is a method for bacterial typing, previously applied for several different species of bacteria. This study aimed at determining the diversity of Staphylococcus epidermidis accessory gene regulator and clonality in clinical isolates from intensive care unit patients, Tehran, Iran.
A total of 59 Staphylococcus epidermidis isolates were obtained from intensive care unit patients. The MLVA was performed for S. epidermidis isolates, using seven VNTR loci, including SE2395, SE0331, SE 828, SE1632, SE0175, Se2, and Se4. Specific primers were used for agr diversity determination.
The agr type I was observed in 29 (49%), while each of the agr type II and agr type III were observed in 10 (17%). Furthermore, 10 (17%) isolates were untypeable with using primers. In total, 49 MLVA genotypes were discriminated. Isolates were classified to six clonal complexes. Of the 59 isolate, 33 were included in clonal complex 1 (CC1), the largest of which harbored 15 (45.4%) agr type I.
Agr type I was observed in the majority of the isolates. The MLVA results of this study suggest that there was a clone with 33 samples, comprised of 56% of isolates; smaller clones each comprised of two to seven isolates, and four isolates in the form of singleton. It seems that big clone isolates were settled in the intensive care unit (ICU), and singleton isolates entered the ward by visitors or medical personnel and caused infection.

CTX-M is the most prevalent and rapidly growing type of the extended-spectrum β-lactamase (ESBL) family and CTX-M1 is the most common type of blaCTX-M.
The current study aimed at investigating the genetic diversity of CTX-M-1-producing Klebsiella pneumoniae circulating in Semnan, Iran evaluated by multilocus variable-number tandem repeat analysis (MLVA).
A total of 110 isolates of K. pneumoniae were collected from different clinical samples. The antibiotic suceptibility and double disk synergy test were determined according to CLSI (the clinical and laboratory standards institute) guidelines. The polymerase chain reaction (PCR) method was performed to detect CTX-M-1. The eight loci for MLVA genotyping were selected along with the primers previously described.
Imipenem, with 84.7% susceptibility, was the most effective antibiotic against K. pneumoniae. Seventy (63.63%) isolates had ESBL positive results and 42 (60 %) of them were positive for CTX-M-1 gene. Totally, 28 MLVA genotypes were discriminated, evaluation of diversity indexes (DIs) for eight loci showed that six different alleles were the most polymorphic and the most DI was 0.807.
The findings of the current study demonstrated heterogeneity among CTX-M-1-producing K. pneumonia strains. The presence of CTX-M-1 in different MLVA types demonstrated that a certain clone is not responsible for spreading the isolates.

Klebsiella pneumoniae as an opportunistic pathogen can be the cause of a range of nosocomial and community - acquired infections. Many virulence factors help these bacteria overcome an immune system and cause various diseases. K1 and K2 capsular antigens, also magA, wcaG, and rmpA are well - known K. pneumoniae virulence factors. Klebsiella pneumoniae has been revealed to have the ability to acquire resistance to many antibiotics, which cause treatment failure.
This study aimed at determining the prevalence of magA, wcaG, rmpA, Capsular type K1, Capsular type K2, TEM, and SHV in K. pneumoniae isolates.
A total of 173 non - duplicate K. pneumoniae isolates were collected from two different hospitals in Semnan, Iran, from urine specimens. Klebsiella pneumoniae was identified by conventional bacteriological tests. Disk diffusion test was performed according to the guidelines of the Clinical and Laboratory Standards Institute (CLSI). Detection of virulence factors, TEM, and SHV gene was performed by specific primers.
Frequency of virulence factors was as follow: capsular type K2: 32.9%, rmpA: 20.2%, capsular type K1: 6.9%, and wcaG: 16.2%. Also, the SHV and TEM were observed in 46.8% and 33.5%, respectively. Antibiotics resistance rates were as follow, imipenem: 7.5%, ciprofloxacin: 16.1%, levofloxacin: 17.3%, amoxicillin - clavulanic acid: 30%, trimethoprim - sulfamethoxazole: 32.9%, cefepime: 34.1%, nitrofurantoin: 35.8%, amikacin: 36.4%, aztreonam: 39.3%, ceftazidime: 42.7%.
Frequency of some virulence factors including capsular type K2, rmpA, wcaG, and also resistant rate to imipenem, amikacin, and ceftazidime were significantly higher than similar studies. Presence of virulence factors accompanied by drug resistance should make bacteria an infectious agent and lead to treatment failure.

Staphylococcus epidermidis, a member of the human flora, is recognized as an opportunistic pathogen and cause of nosocomial infections. Staphylococcus epidermidis surface components are able to establish bacteria on the host surface, and cause infection.
The frequency of icaA, IS256, aap, fbe and bhp in clinical isolates of S. epidermidis were investigated in this study.
Fifty-nine S. epidermidis isolates were collected from blood (50), wound (1), urine (4) and tracheal (4) samples (Tehran, Iran). Staphylococcus epidermidis isolates were identified with conventional bacteriological tests. Virulence-associated genes were detected by specific polymerase chain reactions (PCRs).
Of the 59 S. epidermidis, fbe was found in 89.8%, while aap and bhp were observed in 64.4% and 15.3% of the samples, respectively. Coexistence of aap and fbe was found in 32 isolates, while coexistence of bhp and fbe was observed in five isolates. Two isolates were negative for the investigated genes.
Prevalence of fbe and aap was significantly different from similar studies, yet frequency of bhp was in accordance with other studies. Prevalence of icaA and IS256 was not significantly different from some studies while a significant difference was observed when results were compared with some other studies.

Staphylococcus epidermidis is considered to be an important opportunistic pathogen. S.epidermidis ability to cause infection is due to its biofilm formation ability. Several bacterial molecules act as S. epidermidis adhesion objects and play role in bacterial adhesion to protein or polymeric surfaces. This study aimed to determine the correlation of virulence factors and macroscopic biofilm formation in S. epidermidis clinical isolates.
A cross-sectional study was conducted including 59 S. epidermidis obtained from blood, urine, tracheal and wound samples in Tehran, Iran. S. epidermidis was identified by conventional bacteriological tests. Phenotypic biofilm formation assay was done by microtiter plate method. The virulence associated genes including icaA, IS256, aap, bhp and fbe were detected by specific PCR.
From 59 isolates 36 (61%) were able to produce macroscopic biofilm, of which 12(33.3%) were strong biofilm producers. Of the 36 biofilm producers, 32 (88.9%) were positive for icaA. The majority of the isolates carried fbe (91.7%), IS256 (77.8%), aap (72.2%), while bhp was presented only in (15.3%).
This study demonstrated that the presence of virulence factors is correlated with macroscopic biofilm production. The presence of these virulence factors enables S. epidermidis to produce biofilm, colonize and survive in patients. In the case of immune system compromising or hospitalized patients, infections can occur and would be more complicated than the antibiotic resistance cases

Coagulase-negative staphylococci (CoNS), especially Staphylococcus epidermidis, are considered as normal flora of human epithelia and also important opportunistic pathogens for nosocomial infections. S. epidermidis can also act as a reservoir for mecA, responsible for high-level resistance to methicillin and transferring it to S. aureus.. The aim of this study was to determine the prevalence of S. epidermidis as well as antibiotic susceptibility pattern and mecA prevalence in S. epidermidis isolated from intensive care unit (ICU) patients.. A cross-sectional study was conducted from September 2010 to September 2011 and 184 coagulase-negative staphylococci were collected from different clinical samples in three hospitals. S. epidermidis was identified by conventional bacteriological tests. Antibiotic susceptibility testing was performed using disk diffusion method. Frequency of mecA was detected by specific PCR.. Frequency of S. epidermidis was 34.8%, the most susceptibility was seen to linezolid and vancomycin, and the least susceptibility was seen to tetracycline.Majority of the S. epidermidis isolates carried mecA (92.2%). The most common resistant pattern was trimethoprim-sulfamethoxazole, tetracycline, erythromycin, and methicillin resistance, found in 23.4% of the isolates, followed by resistance to methicillin as the second-most common resistant pattern, observed in 20.3% of the isolates.. Frequency of S. epidermidis was significantly lower, compared to other studies. Presence rate of mecA and susceptibility to linezolid and vancomycin did not show significant differences with other investigations, while resistant to trimethoprim-sulfamethoxazole was significantly lower compared to other investigations, and resistance to tetracycline was significantly higher in comparison to other investigations. Presence of methicillin-resistant S. epidermidis in ICU patients, especially in individuals with compromised immune systems, may cause infection and would be more complicated in the case of antibiotic resistance..

Urinary tract infection is one of the most common bacterialinfections in the human population, and more frequent infection during pregnancy. With noticeto this point that most of urinary tract infections during pregnancy are asymptomatic, they couldlead to serious complications such as prematurity, low-birth weight, hypertension, and higher fetalmortality rates if untreated. This study was aimed to determine the prevalence of asymptomaticbacteriuria, bacterial agents and their antibiotic susceptibility pattern in pregnant women attendingSemnan public health centers during 2007-8.Patients and In this descriptive cross sectional study, pregnant women attendingSemnan public health centers during May 2007 and June 2008 were investigated. Clean catch midstream urine samples were collected and cultured on Eosin Metylene Blue agar and Blood agar bycalibrated loop method. Suspected colonies were identified, antibiotic susceptibility test was done. Of 297 samples, 10 (3.3%) were positive for asymptomatic urinary tract infection. Thedominant bacterial isolate was Escherichia coli (70%). The antibiotic susceptibility was observedto ciprofloxacin, ceftazidime and cefotaxime (80%), the most resistance was amoxicillin- clavulanicacid (90%). Frequency of asymptomatic UTI in pregnant women in this study is significantlylower than similar studies. Antibiotic susceptibility rate to using antibiotics do not show significantdifferences with most other studies.

Salmonella infections are endemic in many developing countries with poor sanitary conditions, but emerge sporadically as a serious public health threat in developed countries. Infections with multidrug resistant (MDR) strains of Salmonella have been associated with treatment failures. Salmonella spp. resistant to extended spectrum cephalosporins are increasing in prevalence worldwide. The aim of this study was to determine the antimicrobial susceptibility, multidrug resistance and extended spectrum beta lactamase (ESBL) production among clinical isolates of Salmonella spp. during 2007 in Tehran, Iran.Patients and In this cross-sectional study, fifty Salmonella spp. were identified by API 20E system and serotyped by the slide agglutination test. Disk diffusion test was performed. Double disk synergy test was used as a screening test for ESBL production, using disks of cefotaxime andceftazidime with and without clavulanic acid. From 50 Salmonella spp. 12 (24%) were S. enterica serogroup paratyphi B, 24 (48%)S. enterica serogroup paratyphi C and 14 (28%) were S. enterica serogroup Typhi. The most susceptibility and resistance were observed to ceftazidime (98%) and amoxicillin-clavulanic acid (96%), respectively. 28(56%) were resistant to 5 or more antibiotics. ESBL production was detected by double disk synergy test in one isolate (2%). Results showed increase in antibiotic and multidrug resistance pattern of Salmonella spp. comparing to previous studies in Iran and other countries. It seems that this is the first reportof Salmonella spp. ESBL producing in Iran.

β-lactamase production is the predominant mechanism for resistance to β-lactams in Enterobacteriaceae. The producing isolates are often multidrug resistant and are major hosts for extended spectrum β-lactamases. This study was designed to determine the prevalence of extended-spectrum β-lactamase producing isolates of Escherichia coli and Klebsiella pneumoniae and their antibiotic resistance patterns in Semnan, Iran. 275 Escherichia coli and 107 K. pneumoniae isolates from clinical specimens were investigated. Combined disk test was used as a screening test for ESBL production. Disk diffusion test was performed for antibiotic susceptibility testing. The greatest resistance was observed against ampicillin (96.3%) and the least resistance was against ceftazidime (16.5%). Using combined disks as phenotypic confirmatory test, ESBL were detected among 69 (18.1%) of all isolates. Frequency of ESBL production was 17.45% and 19.6% for E. coli and K. pneumoniae respectively. High levels of resistance and ESBL production found in the E. coli and K. pneumoniae in this study make the choice of empirical antibiotic regimens difficult. Antimicrobial susceptibility testing and ESBL production monitoring are recommended in patients