Iranian Journal of Microbiology
Volume:9 Issue: 4, Aug 2017

Designing control and therapeutic policies for antibiotic resistant Streptococcus pneumoniae, which is an important causative agent of several invasive and noninvasive infectious diseases and its carriage rates, has been described as the main target in World Health Organization (WHO). The present study was conducted to determine antibiotic resistance pattern, evaluate biofilm forming ability in S. pneumoniae isolates, and find the genetic relationship between cultured strains.
Following the isolation and identification of S. pneumoniae strains from nasopharyngeal swabs, the ability of biofilm formation and susceptibility pattern of the isolates were screened using semi-quantitative microplate and disk diffusion procedures. Subsequently, Pulse field gel electrophoresis (PFGE) method was used to determine the clonal diversity of isolates.
The pneumococcal colonization rate in this study was found to be 24%. A large number of our isolates had strong biofilm forming ability. However, there was variation in antibiotic resistance patterns of isolates in children who lived in nursery houses. The genetic similarity among the isolates in PFGE varied from 26.5% to 100% in our isolates. This was the first report of biofilm formation of nasopharyngeal colonized S. pneumoniae in Iran. Genetic variations were also noticeable, when the isolates were fingerprinted by PFGE.
The findings of this study revealed the need for thoughtful use of antimicrobial agents, continued monitoring of pneumococcal resistance patterns, and prevention of the spread of multi-drug resistant clones.

The antimicrobial combination with synergistic mechanism is recommended to provide broad-spectrum coverage, and prevent the emergence of resistant mutants. In the present study, the synergistic activity of lysostaphin with linezolid, oxacillin and vancomycin, against methicillin-resistant Staphylococcus aureus (MRSA) clinical isolates was determined.
Seventy-three MRSA isolates collected from clinical specimens were tested, for in vitro synergistic activity of lysostaphin with linezolid, vancomycin and oxacillin, by checkerboard assay.
Lysostaphin showed synergistic activity with linezolid and oxacillin, against all MRSA isolates, tested in the present study. Whereas, only 19.1% of the isolates showed synergistic activity with vancomycin and remaining 80.9% of the MRSA isolates showed additive activity.
Lysostaphin causes rapid lysis of S. aureus. Combination therapies that include linezolid and lysostaphin could be used in life-threatening infections, such as endocarditis to increase the early in vivo activity of the antibiotics, and to prevent the emergence of linezolid resistant mutants. Further, in vivo studies are warranted to confirm our results.

Q fever is a zoonotic disease and farm animals serve as the main reservoir of the disease. The aim of this study was to evaluate the seroprevalence of Q fever in sheep, in Lorestan province in western Iran.
In this cross-sectional study, 330 blood samples were collected from sheep, from each county in Lorestan province. The samples were tested by ELISA for the presence of immunoglobulin (IgG) against Coxiella burnetii.
Among the samples tested, 45 samples (13.64%) were seropositive. Of 35 studied herds, 21 (60%) had a history of infection. In terms of number of positive samples, there was no significant difference between the three geographical regions (central, west and east) (p=0.687). There was no statistically significant difference between age groups (p =0.604). Gender also had no effect on infection rates, in female and male sheep (p =0.814). No significant difference was observed between the number of lactation and positive serology (p =0.376). The rate of infection with Q fever and abortion also had no statistically significant difference (p =0.152).
The findings of this study showed that sheep in Lorestan were infected by Q fever and the cycle of disease transmission had been established between animals and ticks.

Bordetella holmesii is associated with a pertussis-like respiratory syndrome in healthy individuals and also a rare cause of septicaemia, endocarditis, pneumonia, and septic arthritis, mostly in immunocompromised patients. Culture technique and real-time PCR are 2 methods used to detect Bordetella spp.
In this study, 435 nasopharyngeal specimens of patients with suspected whooping cough were checked for the presence of B. holmesii using 2 methods of culture technique and real-time PCR.
In this study, we detected hIS1001 and IS481 of B. holmesii in 2 infants suspected of having pertussis-like syndrome.
Our observations demonstrate that accurate diagnosis is needed to discriminate between B. holmesii and B. pertussis infections among pertussis cases; otherwise, it could lead to misestimating pertussis rate and vaccine efficacy.

Human milk is a continuous supply of Lactic Acid bacteria (LAB), including enterococci with probiotic potentials. The aim of this study was to analyze two Enterococcus species, isolated from human milk for their probiotic potential, bacteriocin producing ability and virulence traits.
Enterococcus faecium TA0033 and E. faecalis TA102 were tested for acid and bile tolerance, survival in simulated gastric and intestinal conditions. The antibacterial spectrum of the isolates was tested by agar well diffusion assay. The antagonistic agent was characterized by physico-chemical methods. The enterocin structural genes, virulence determinants, vancomycin resistance and biogenic amine genes, such as hdc1, hdc2, tdc, ldc and odc were also determined.
The tested isolates survived acidic conditions, high bile salt (1%), simulated gastric and intestinal conditions. The culture supernatant fluids of the two isolates inhibited the growth of Escherichia coli, Listeria monocytogenes, Salmonella typhi, Staphylococcus aureus, Shigella dysenteriae and Streptococcus agalactiae. The antagonistic activity was lost in the presence of proteolytic enzymes but tolerated the action of catalase, lysozyme and lipase. In contrast to enterocin TA102, enterocin TA0033 possessed bactericidal mode of action. Bacteriocin structural genes, entA and entB were present in the genome of the two isolates, while E. faecalis TA102 additionally harboured entP and bac31 genes. The phenotypic and genotypic virulence assessment studies indicated hyaluronidase (hyl) production and vancomycin resistance in E. faecalis TA102 while, none of the isolates harboured the biogenic amine genes.
The presence of virulence genes in E. faecalis TA102 calls for careful monitoring of Enterococcus isolates for their safety parameters.

Probiotics are live microorganisms, which show beneficial health effects on hosts once consumed in sufficient amounts. LAB group can be isolated and characterized from traditional dairy sources. This study aimed at isolating, identifying, and in vitro characterizing (low pH/high bile salt tolerance, antibacterial activity, and antibiotic susceptibility) LAB strains from traditional Iranian dairy products.
Isolated strains were identified by Gram staining, catalase assay, and 3 molecular identification methods; namely, (GTG) 5-PCR fingerprinting, ARDRA, and 16S rDNA gene sequencing.
A total of 19 LAB strains belonging to 4 genera (Lactococcus, Leuconostoc, Lactobacillus and Enterococcus) were identified.
The experiments revealed that L. plantarum 15HN, L. lactis subsp. cremoris 44L and E. mundtii 50H strains, which were isolated from shiraz, cheese and shiraz, respectively, displayed a desirable tolerance to low pH and high bile salts, favorable anti-pathogen activity, and acceptable antibiotic susceptibility; hence, they could be considered as novel probiotic candidates and applied in the food industry.

Cholera is a life-threatening diarrhea caused mainly by Gram-negative marine habitant Vibrio cholerae serogroup O1. Cholera vaccination is limited mainly to developed countries, due to the cumbersome and expensive task of vaccine production. In the present work, the aim was to study the immunogenicity of the synthetic mimotopes through two different routes of injection and oral administration. Lipopolysaccharide (LPS) is one of the immunogenic components in Gram-negative bacteria, which cannot be used as a vaccine candidate, due to its high toxic effect.
Three phage-displayed selected peptides, with high affinity to anti-LPS VHH tested in our previous study, were chemically synthesized and used as a potential vaccine candidate. In order to enhance the antigenic properties and safe delivery, these peptides were conjugated to BSA as a carrier and encapsulated with PLGA. Peptides were injected intra-peritoneally or administered orally, alone or in combined form. Mice sera and feces were collected for assessment of humoral and mucosal antibody titers, respectively. ELISA plates were coated with mimotope conjugates and V. cholerae, Shigella sonnei and ETEC were used as target antigens. Antibody titer was measured by adding IgG and IgA as primary antibodies.
Mice receiving three selected synthetic peptide conjugates (individually or in combination) showed higher antibody titer compared to control groups. The mice immunized with synthetic peptides were protected against more than 15 LD50 of V. cholerae.
These peptides are mimicking LPS and can potentially act as vaccine candidates against V. cholerae.

Polytopic antigens are recently applied for replacing crude antigens, for control of infectious agents. The surface of the Toxoplasma is covered with immunogenic antigens namely surface antigens (SAGs). These antigens possess several immunogenic epitopes, inducing immune responses.
In this study, a DNA construct comprising of sequences encoding epitopes from SAG1, 2 and 3 was designed and cloned into pET28a expression vector and subsequently expressed and purified, using Ni-NTA column.
The SDS-PAGE and Western blotting analysis showed that polytopic genes were successfully expressed and purified.
The surface antigenic protein of T. gondii can be applied in the future epitope-based applications.