Iranian Journal of Microbiology
Volume:8 Issue: 2, Apr 2016

Bacterial resistance to conventional antibiotics has become a widespread public health prob- lem. The aim of this study was to investigate the influence of zinc oxide nanoparticles (ZnO NPs) on the antibacterial activity of several conventional antibiotics against Pseudomonas aeruginosa.
ZnO NPs were prepared by solvothermal method and dispersed in glycerol with the help of ammo- nium citrate as a dispersant. The antibacterial effects of the resulting ZnO nanofluid, ceftazidime, tobramycin, and ciproflox- acin were investigated against two P. aeruginosa strains, including one clinical isolate and P. aeruginosa ATCC 9027 using microdilution method. For the evaluation of the combined effect of ZnO nanofluid and antibiotics, the fractional inhibitory concentration indices were calculated and isobolograms were plotted.
Clinical strain in comparison to standard strain of P. aeruginosa showed more resistance to ZnO nanofluid and the antibiotics. ZnO nanofluid acted synergistically with ceftazidime and tobramycin against both strains. Combination of ZnO nanofluid and ciprofloxacin displayed synergistic and partial synergistic activity against clinical and standard strains of P. aeruginosa, respectively.
The results suggest that bacterial resistance to antimicrobials could be reduced by the synergistic action of ZnO NPs.

The most prevalent and worldwide oral disease is dental caries that affects a significant pro- portion of the world population. There are some classical approaches for control, prevention and treatment of this pathologic condition; however, the results are still not completely successful. Therefore new methods are needed for better management of this important challenge. Chitosan is a natural and non-toxic polysaccharide with many biological applications, particu- larly as an antimicrobial agent. Chitosan nanoparticle is a bioactive and environment friendly material with unique physico- chemical properties. The aim of the present study was to investigate the antimicrobial effect of chitosan and nano-chitosan on the most important cariogenic streptococci.
For evaluation of antimicrobial effect of chitosan and nano-chitosan against oral streptococci broth micro-dilution method was carried out for four bacterial species; Streptococcus mutans, Streptococcus sobrinus, Streptococ- cus sanguis and Streptococcus salivarius. Also the effect of these materials on adhesion of above bacteria was evaluated. One-way ANOVA and post hoc Tukey test were used for statistical analysis.
The MICs of chitosan for S. mutans, S. sanguis, S. salivarius and S. sobrinus were 1.25, 1.25, 0.625 and 0.625 mg/ mL, respectively. The MIC of chitosan nanoparticle for S. mutans, S. salivarius and S. sobrinus was 0.625 mg/mL and for S. sanguis was 0.312 mg/mL. Chitosan and chitosan nanoparticles at a concentration of 5 mg/mL also reduced biofilm forma- tion of S. mutans up to 92.5% and 93.4%, respectively.
The results of this study supported the use of chitosan and chitosan nanoparticles as antimicrobial agents against cariogenic Streptococci.

The USEPA has suggested faecal enterococci as the primary bacterial indicators. Of more importance is their direct correlation with swimmer-associated gastroenteritis in recreation water quality monitoring. In contrast to other seawater bodies with 3.5% salinity, the recreational waters in the southern coast of the Caspian Sea possess its own salinity (about 1% w/v) and thus require further investigations to determine the capacity of Enterococcus faecalis as the sole primary microbial index in this unique aquatic environment.
The survey of the presence and survival of E. faecalis as a microbial index in the recreational waters of the southern Caspian Sea was carried out using a microcosm as an experimental model. The concentration of E. faecalis cells in samples of seawater were estimated by a standard membrane filtration method using m-Enterococcus agar as the selective culture medium. As the current standard culture-based methods are not reliable enough for the detection of non-growing, damaged and under-tension bacteria, PCR was used to identify the possible VBNC form of the bacterium after disappearing of the culturable cells.
Results and A continuous decline in the number of culturable E. faecalis cells resulted in apparent elimination of the bacteria from seawater in a defined period. Detection of intact DNA was possible in the following 60 days. The salinity of about 1% and the self-purification properties of the Caspian Sea make the conditions feasible for the use of this microorganism as a measure of water quality throughout the region. The results confirmed the presence of damaged bacterial cells, namely VBNC forms, indicating the necessity of examining of the sea water samples by using molecular approaches or repair procedures.

Adhesion and colonization are prerequisites for the establishment of bacterial pathogenesis. The biofilm development of Pseudomonas aeruginosa was assessed on adhesive surfaces like dialysis membrane, stainless steel, glass and polystyrene.
Microtiter plate biofilm assay was performed to assess the effect of nutrient medium and growth parameters of P. aeruginosa. Further, its growth on adhesive surfaces namely hydrophilic (dialysis membrane) and hydrophobic (polystyrene plate, square glass and stainless steel coupon) was assessed. The exopolysaccharide (EPS) was quantified using ruthenium red microplate assay and microscopic analysis was used to observe P. aeruginosa biofilm architecture. The anti-biofilm activity of herbal extracts on mature P. aeruginosa was performed.
The formation of large scale biofilms on dialysis membrane for 72 h was proved to be the best surface. In microscopic studies, very few exopolysaccaride fibrils, indicating a rather loose matrix was observed at 48 h. Further, thick exopolysaccaride, indicated higher adhesive properties at 72 h which is evident from ruthenium red staining. Among the plant extract used, Justicia wynaadensis leaf and Aristolochia indica (Eswari) root extract showed significant reduction of anti-biofilm activity of 0.178 OD and 0.192 OD in inhibiting mature biofilms at 0.225 OD respectively, suggesting the possible use of these extracts as efficient anti-adhesive and biofilm-disrupting agents with potential applications in controlling biofilms on surfaces.
Our study facilitates better understanding in the development of P. aeruginosa biofilms on different food processing and clinical surfaces ultimately taking care of food safety and hygiene.

Brain abscess remains a potentially fatal central nervous system (CNS) disease, especially in developing countries. Anaerobic abscess is difficult to diagnose because of cumbersome procedures associated with the isolation of anaerobes .
This is a hospital-based retrospective microbiological analysis of 430 brain abscess materials (purulent aspirates and/or tissue), for anaerobic organisms, that were received between 1987-2014, by the Microbiology Laboratory in our Institute.
Culture showed growth of bacteria116/430(27%) of the cases of which anaerobes were isolated in 48/116(41.1%) of the cases. Peptostreptococcus (51.4 %), was the predominant organism isolated in four cases followed by Bacteroides and Peptococcus species.
Early diagnosis and detection of these organisms would help in the appropriate management of these patients.

The emergence and spread of multidrug resistant (MDR) and extended spectrum β-lactamase (ESBL) producing strains reduces the number of effective drugs that can be used for treatment. The aim of this study was to evaluate the susceptibility profile of Enterobacteriaceae isolated from UTIs, specifically MDR and ESBL producing strains, to fosfomycin and other antibiotics.
The study was performed during a 6 month period (February 2014 to August 2015). A total of 219 non-duplicate urinary isolates of Enterobacteriaceae were collected. Identification and susceptibility testing was done according to standard microbiological procedures and the Kirby- Bauer test, respectively. Based on the results obtained from susceptibility testing, MDR bacteria were recovered and identification of ESBL production was done according to CLSI recommendation.
Isolates of E. coli and Klebsiella spp.were responsible for 80.8% and 12.8% of patients with UTIs respectively. The rates of resistance to ampicillin, cefazolin, nalidixic acid, trimethoprim-sulfamethoxazole were 86.3%, 79.4%, 68.5% and 63.9% respectively. In contrast, high sensitivity rates were detected to fosfomycin, amikacin and amoxicillin-clavulanic acid with 97.3%, 91.8% and 80.8%, respectively. Of all isolates, 167 (76.3%) were detected as MDR and 75 (34.2%) as ESBL producing strains.
The rate of antibiotic resistance among uropathogens Enterobacteriaceae is remarkably high. The most effec- tive antibiotic was fosfomycin. Moreover, susceptibility to fosfomycin is over 90% for MDR and ESBL producer isolates. Therefore, fosfomycin can be a good option for treating UTIs.

HBHA and Mtb32C have been isolated from culture supernatants of Mycobacterium tu- berculosis (M. tuberculosis) and Mycobacterium bovis (M. bovis) and their immunogenicity previously studies have been confirmed. In this study, capability of constructed vector containing two mycobacterial immunodaminant antigens (Mt- b32C-HBHA), in producing new chimeric protein under the in-vitro condition was examined.
In present study Huh7.5 cells was transfected with Mtb32C-HBHA –pCDNA3.1 recombinant vector using the calcium phosphate method and expression of chimeric protein was assessed by RT-PCR and Western blot methods.
Results of RT-PCR and Western blot showed expression of 35.5 KD recombinant protein (Mtb32C-HBHA) in thiscell line.
The constructed vector can produce two highly immunogenic antigens that fusion of them to gather makes chi- meric antigen with new traits. Other attempts are needed to evaluate specific properties of this new antigen such as molecular conformation modeling and immunologic characteristics in future studies.

In present study we aimed to clone the luxI gene encoding N-acyl-homoserine synthase detected in biofilm forming clinical isolates of Acinetobacter baumannii and study its expression in Escherichia coli transformants.
Four A. baumannii hospital strains which demonstrated strong biofilm activity were selected in this investigation. The presence of luxI gene was detected using PCR technique. Purified PCR product DNA was initially cloned to pTG19 plasmid embedded with overhang 3'dT residue and transformed to Escherichia coli K12 DH5α (luxI- mutant). The gene was then recovered from agarose gel after digestion after digestion with DraI restriction enzyme and ligated by T4 DNA ligase into pET28a expression vector using NdeI and XhoI enzymes. Recombinant (pET28a luxI) was transformed into E. coli BL21 (DE3) containing knockout luxI- gene. The luxI putative gene was further detected in transformants by colony PCR. Expression of the luxI gene in the recombinant E. coli BL21 cells was studied by quantitative real time PCR (qRT-PCR) and the presence of N-acyl-homoserine lactone (AHL) in wild types and the transformants were checked by colorimetric assay and Fourier Transform Infra- Red (FT-IR).
In our study, we found successful cloning of AHL from A. baumannii strain 23 which showed high biofilm. The presence of luxI gene in recombinant E. coli BL21 was confirmed by PCR. There was four fold increases in expression of luxI in the transformants (P ≤ 0.05). To verify the AHL synthesis, it was found that, strain 23 and the transformants showed highest amount of AHL activity (OD = 1.524). The FT-IR analysis indicated stretching C=O bond of the lactone ring and primary amides (N=H) at 1764.69 cm-1 and 1659.23 cm-1 respectively.
From above results we concluded that, luxI and AHL are the only quorum sensing elements existed in A. baumannii and pET28a vector allows efficient AHL expression in E. coli BL21 transformants.

Varicella Zoster Virus (VZV) infection in pregnant women can cause complications for the mother and fetus. The aim of this study was to assess the immunity against VZV among young women before marriage.
In this cross-sectional study 250 of women referring to health centers in Sanandaj, Iran, for pre-marital medical check-up were selected. The VZV IgG was measured by ELISA and demographic characteristics including age, place of residence, number of siblings, occupation, education and history of chickenpox were also collected. Data were analyzed using the R statistical package. To investigate the potential relationship between the variables Chi-square or Fisher's exact tests were used.
Out of 250 women, 178 (71.2%) were diagnosed as antibody positive and 72 (28.8%) as negative. The immunity increased with the individual’s age group (P Noticeable percentages of women were susceptible to VZV, therefore during pregnancy are at risk of infection and possibility of the fetus abnormalities. Screening the immunity and further studies on the need of vaccination before marriage is suggested.

Human Herpes 6 virus (HHV-6) could remain latent and chronic in the host cells after primary infection. HHV-6 genome encodes certain trans activation proteins which may results in development of malignantlymphoma. The association of human herpes six virus (HHV-6) infection and Hodgkin and Non-Hodgkin lymphomas is strongly supported by epidemiological studies. The aim of this study was to determine the prevalence of HHV-6 among the patients with Hodgkin, Non- Hodgkin`s lymphoma.
Overall 44 blocks of formalin-fixed, paraffin-embedded of the patients including 22(50%) Hodgkin and 22(50%) Non-Hodgkin Lymphoma were collected. Initially the section of 5μm-thickness were prepared from the formalin-fixed, paraffin-embedded tissue blocks. Then the deparaphinazation was carried out for each sample. The DNA was extracted, followed by nested PCR for detection of HHV-6. Based on PCR product size and sequencing, the HHV-6 A or B subtypes were characterized.
12/22(54.54%) cases of Hodgkin and 8/22 (36.36%) Non-Hodgkin’s lymphoma were shown as positive for HHV-6. Out of 12 positive HHV-6 in Hodgkin lymphoma, 10 patients (45.45%) belonged to variant A while 2 cases (9.09%) were found positive for both HHV-6A and HHV-6B. All the Non Hodgkin samples (n=8, 36.36%) showed positive for HHV-6 variant A.
High prevalence of HHV-6 was found among the patients with Hodgkin and Non-Hodgkin’s lymphoma. Two patients with Hodgkin lymphoma had mixed HHV-6A and HHV-6B infections. It is recommended patients with Hodgkin and Non-Hodgkin should be screened for HHV-6 detection before chemotherapy.