فهرست مطالب ali shivaee

Nanoparticles are a new generation of antimicrobials. Zinc oxide nanoparticles have attracted a great deal of interest in their medical applications. The aim of the present study was to investigate the effect of zinc nanoparticles on the expression of mrkA and fimA genes in drug-resistant K. pneumoniae.

A total of 30 clinical isolates of K. pneumoniae were collected from Sina hospital and all the isolates were identified by biochemical tests. Antimicrobial resistance pattern was determined by disk diffusion method. PCR method was used to investigate the presence of mrkA and fimA genes. Biofilm phenotypic test was performed and after conducting MIC test by micro dilution method, realtime PCR was used to study the effect of zinc oxide nanoparticle on the expression of fimA and mrkA genes.

The highest resistance rate was against cefotaxime and ceftazidime antibiotics (67%). Twenty seven isolates harbored fimA gene while 24 isolates harbored mrkA gene. Five isolates were identified as strong biofilm producers. MIC values for zinc oxide was 2500 µg/ml in all five isolates. Results of real-time PCR showed that the expression levels of mrkA and fimA genes in isolates treated with zinc oxide decreased 8.5 and 9 fold, respectively, compared with the control.

This study suggests that zinc oxide can be a suitable candidate for the inhibition of the two studied virulence genes in K. pneumoniae.

Listeriosis can be fatal for vulnerable groups of society. The disease has been widespread in recent years due to the large consumption of dairy and meat products. There is little information about the susceptibility of antibiotics and the pattern of Listeria monostigenesis gene resistance in Iranian society. Accordingly, the present study was conducted to investigate the antibiotic susceptibility and genetic resistance pattern of Listeria monosteogenesis strains isolated from different clinical and environmental sources.

In this study, 55 isolates were tested for antibiotic susceptibility by disk diffusion in agar and genetic pattern by polymerase chain reaction (PCR).

91% and 83% of the strains were resistant to streptomycin and Trimethoprim/sulfamethoxazole respectively. The result of PCR of antibiotic resistance genes showed that the prevalence of ermA, ermB, strA, tetA, tetS and ermC genes in isolates of Listeria monocytogenes was 50.90% (28/55), 21.81% (12/55), 89.9% (49/55), 0% (0/55), 21.81% (12/55) and 0% (0/55), respectively.

Due to the presence of 1/2a and 1/2c serotypes in isolated isolates and the presence of marker virulence genes in these strains, these isolates have potential for biological risks and listeriosis disease. Existence of this genetic pattern and resistance pattern can be partly due to the use of antibiotics during the production of dairy products. Regarding results of this study, the manner and rate of using animal antibiotics can be managed.

Biofilm formation is one of the most important factors in the development of infections caused by Staphylococcus aureus. In this study, the expression levels of genes responsible for biofilm formation were studied in methicillin sensitive and methicillin resistant S. aureus. A total of 100 meticillin-resistant s.aureus (MRSA) and meticillin-sensetive s.aureus (MSSA) isolates were studied. Bacterial biofilm formation was evaluated phenotypically using microtiter plate method. Real-time PCR tests were conducted to determine the expression levels of genes involved in biofilm formation. Quantitative biofilm formation test was repeated three times for each specimen. The prevalence of weak, medium, and strong biofilm producers were 16%, 49%, and 35%, respectively. In MSSA isolates, expression levels of ica genes increased compared to the fnbA, fnbB, clfA and clfB genes. These results were different in MRSA isolates, and ica genes showed a decreased gene expression levels compared to the aforementioned genes.   Considering the results of this study, clf genes probably contribute to the same extent in both MRSA and MSSA isolates, and there is probably no significant difference in the role of these genes in these isolates. In addition, the results of this study indicated that MRSA may not use the conventional route for biofilm formation and may use independent pathways through Polysaccharide intercellular adhesion (PIA).

     More than 30 bacterial, viral, and parasitic pathogens have the potential for transfusion (sexually transmitted), an infectious group called sexually transmitted infections (STIs). Atofobium vagina, Gardnerella vaginalis are one of the most common causes of the disease. T. vaginalis is also the most common protozoa among vaginosis causing agents. This study aimed to determine the prevalence of these factors in conjunction with the multiplex PCR method.

    In this study, among 320 women who referred to Shahid Akbarabadi Hospital in Tehran, 70 samples of people with symptoms of vaginosis who had not taken antibiotics at least one week before the visit were selected. The results of the Amsel criteria and Nugent score tests indicated only 27 cases as bacterial vaginosis. After DNA extraction from the specimens, a multiplex PCR was performed on the samples.

     The results of the multiplex PCR showed that in 27 cases, 14 cases of bacterial vaginosis only in terms of A. vaginalis, 21 cases were only G. vaginalis and 10 were positive for both bacteria and in the case of T. vaginalis only 1 positive sample was observed among all samples of vaginosis, which was also positive in the A. vaginalis.

    The results of this study showed that multiplex PCR could be of great help in the diagnosis of bacterial vaginitis diseases.

Klebsiella species are common causes of nosocomial, ulcers, blood and urinary tract infections, and also acquired pneumonia from the hospital and various intra-abdominal infections. Bacterial resistance mechanisms against antibiotics are different, but one of these resistance mechanisms, which is very problematic, is the production of β-lactamase enzymes in bacteria. The aim of this study was to determine the antibiotic resistance pattern and the presence of beta-lactamase genes in Klebsiella isolated from burn wounds among patients referred to Shahid Motahhari Hospital in Tehran.

100 strains collected for confirmation of production of broad-spectrum beta-lactamases (ESBLs) were tested by CDT (Combined Disk Test). Finally, β-lactamase genes were investigated using polymerase chain reaction.

The highest resistance rate was observed to ampicillin (93%). 23% of isolates produced ESBLs. The highest frequency of genes was bla shv gene (26.8%).

The presence of beta-lactamase genes with high antibiotic resistance is very worrying. Since the present genes can spread through mobile genetic elements in bacteria, among bacteria, it is considered to be a serious alert in the treatment of infections caused by Klebsiella.

  Listeria monocytogenes infection during pregnancy may cause spontaneous abortion or stillbirth, or the birth of babies with neonatal meningitis. The aim of this study was to serotype L. monocytogenes isolated from women with spontaneous abortion using polymerase chain reaction.

  Vaginal swab samples were obtained from 96 women with spontaneous abortion. The microbial culture was performed on blood agar and PALCAM agar followed by differential biochemical tests for characterization of L. monocytogenes isolates. Besides, total DNA was extracted from each vaginal specimen, and PCR assay was then carried out using specific primers for target genes of this bacterial species.

   Microbial culture and PCR revealed 4 and 16 L. monocytogenes isolates (out of 96 vaginal specimens), respectively. There was a significant association between consuming unsterilized dairy products and the risk of Llisteria infection (P < 0.001). Various serotypes of L. monocytogenes were detected as follows; the serotypes 1/2b, 3b (31.25%), the serotypes 1/2c, 3c (31.25%), the serotypes 1/2a, 3a (25%), and the serotypes 4 (12.5%).

  However, the difference between frequencies of observed serotypes was not statistically significant (P < 0.05). The 1/2b, 3b, and 1/2c, 3c serotypes of L. monocytogenes are more commonly seen in vaginal specimens of women with spontaneous abortion, and PCR technique as a convenient tool may be used for identifying of causative strains. However, further studies need to improve and optimize this approach.

Klebsiella pneumoniae is an opportunistic microorganism causing nosocomial infection all over the world .This study aimed to investigate the prevalence of biofilm formation in K. pneumoniae isolated from patients and its correlation with the virulence factors. Biochemical tests were used for the identification of K. pneumonia isolated from patients referred to Motahari and Milad hospitals in Tehran, Iran, from October 2015 to June 2016. Kirby-bauer test was performed and biofilm formation was assessed phenotypically. Finally, virulence genes were detected by the PCR method. The highest resistance rate was against ceftazidime and cefotaxime (67%) and the least resistance rate was against imipenem and meropenem (39%). In addition, 81% of the isolates were biofilm producers according to the results of biofilm formation assay. Also, the results of PCR showed that all 57 biofilm producer isolates harbored fimA, mrkA, ecpA, and fimD virulence genes and 92% of these isolates harbored fimH virulence gene. Among non-biofilm producer isolates, 36% had fimA gene, 29% had ecpA gene, and none of these isolates carried mrkA and fimH genes. It seems that antibacterial resistance has a significant association with biofilm formation in K. pneumoniae isolates. Therefore, understanding resistance pattern and mechanisms leading to biofilm formation can facilitate efficient treatment of infections caused by this bacterium.

 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 . 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.

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.


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.