Lactic acid bacteria (LAB) have been considered as potentially probiotic organisms due to their potential human health properties. This study aimed to evaluate both in vitro and in vivo, the potential probiotic properties of Lactobacillus species isolated from fecal samples of healthy humans in Iran. A total of 470 LAB were initially isolated from 53 healthy individual and characterized to species level. Of these, 88 (86%) were Lactobacillus species. Biochemical and genetic fingerprinting with Phene-Plate system (PhP-LB) and RAPD-PCR showed that the isolates were highly diverse consisted of 67(76.1%) and 75 (85.2%) single types (STs) and a diversity indices of 0.994 and 0.997, respectively. These strains were tested for production of adhesion to Caco-2 cells, antibacterial activity, production of B12, anti-proliferative effect and interleukin-8 induction on gut epithelial cell lines and antibiotic resistance against 9 commonly used antibiotics. Strains showing the characteristics consistent with probiotic strains, were further tested for their anti-inflammatory effect in mouse colitis model. Only one L. brevis; one L. rhamnosus and two L. plantarum were shown to have significant probiotic properties. These strains showed shortening the length of colon compared to dextran sulfate sodium and disease activity index (DAI) was also significantly reduced in mouse. Low number of LAB with potential probiotic activity as well as high diversity of lactobacilli species was evident in Iranian population. It also suggest that specific strains of L. plantarum, L. brevis and L. rhamnosus with anti-inflammatory effect in mouse model of colitis could be used as a potential probiotic candidate in inflammatory bowel disease to decrease the disease activity index.

Background: Staphylococcus aureus is associated with different infections ranging from skin and soft tissue infections to endocarditis and fatal pneumonia. S. aureus is still the most common bacterial species isolated from inpatient specimens and the second most common from outpatient specimens. Today, methicillin resistant S. aureus (MRSA) isolates are present in the hospitals of most countries and are often resistant to several antibiotics. Objectives: This study was conducted from 2007 to 2011 to detect prevalence and antibiotic resistance patterns among MRSA and methicillin sensitive S. aureus (MSSA) isolated from hospitals in Tehran, Iran. Materials and Methods: Totally 726 isolates of S. aureus were collected from three referral hospitals in Tehran. All isolates were identified at the species level by standard biochemical tests. Susceptibility to eighteen antibiotics was determined by disc diffusion method. Then oxacillin and vancomycin minimum inhibitory concentration (MIC) of resistant isolates was also determined using Etest. mecA gene was detected using specific primers. Results: A total of 216 (30%) strains were found to be MRSA isolates. The highest antibiotic resistance was to penicillin, clindamycin, tobramycin and tetracycline respectively. Ninety three and 61% of MRSA and MSSA isolates were multidrug resistant (MDR) respectively. However, no strain was resistant to vancomycin, synercid, linezolid and chloramphenicol. Sixty nine percent of MRSA isolates showed high level of resistance to oxacillin (MIC ≥ 256 µg/ml). mecA gene was detected among all MRSA isolates. Conclusions: Although the frequency of MRSA isolates in the current study was low, resistance to other antibiotics was high and most of the isolates were found to be MDR. Regular surveillance of hospital-associated infections and monitoring of their antibiotic sensitivity patterns are required to reduce MRSA prevalence. High frequency of MDR isolates of S. aureus could be considered as an urgent warning for public health. Keywords: Staphylococcus aureus; Vancomycin; Iran

Considering the importance of the poultry industry and the increasing interest in alternative growth promoters, probiotics are considered as a potential candidate for use in the poultry industry. In this study, Lactobacillus species were isolated from 21 rectal swabs of 11 healthy 6-day-old and 10 healthy 21-day-old chickens and their fecal and feed samples. The isolates were characterized and their probiotic characteristics, including resistance to gastric acid and bile salts, biofilm formation and adherence to epithelium or mucus, amylase and protease activity and production of inhibitory compounds, were assessed. From 31 acid and bile resistant lactobacilli, only 2 Lactobacillus brevis and 1 Lactobacillus reuteri strains showed significant probiotic properties. These isolates indicated detectable attachment to Caco-2 cells and significant antibacterial activities against Gram-positive and Gram-negative pathogens. Additionally, phenotypic and genotypic diversity of lactobacilli isolates were studied by Phene Plate (PhP) system (PhP-LB) and random amplified polymorphic DNA (RAPD)-PCR, respectively. PhP-LB results of 24 L. brevis isolates showed a high phenotypic variation among the isolates. In comparison, results of RAPD-PCR highlighted a low diversity. Therefore, it seems that combination of the 2 techniques (PhP and RAPD-PCR) could result in a significant discriminatory power than each of them used alone.

The occurrence of drug-resistant Vibrio cholerae is being reported with increasing frequency worldwide. Spread of resistant strains has been attributed, in part, to class I integrons and sulfamethoxazole trimethoprim-constin (SXT-C). Sixty clinical V. cholerae isolates were isolated from four different provinces in Iran, which were subjected to antibiotic susceptibility testing, polymerase chain reaction amplification of class I integron and SXT-C, and sequencing of the amplified fragments. Ribotyping technique was used to assess the clonality of the isolates. The highest and the least levels of antibiotic resistance were seen to SXT, streptomycin, and chloramphenicol (95%, 95%, and 92%, respectively) and doxycycline, gentamicin, and oxytetracycline (0%, 3%, and 3%, respectively). The results showed that out of the total of 60 isolates, only 1 contained class I integron, which harbored streptomycin resistance gene cassette ( aadA2 ). This isolate showed ribotype pattern similar to the other strains (lacking class I integron) obtained in the same year (2006). On the contrary, the SXT-C was found in 95% of the isolates. These isolates showed three different but related ribotype patterns. Overall, the results of this study showed insignificant contribution of class I integron in antibiotic resistance of our V. cholerae isolates. On the other hand, V. cholerae resistance to SXT, streptomycin, and chloramphenicol could be, in part, due to wide distribution of SXT-C among the isolates. In addition, the ribotype data suggest that the clinical V. cholerae population from 2004 to 2006 were homogeneous.

Staphylococcus aureus is a leading cause of hospital-acquired (HA) and community-acquired (CA) infections worldwide. Recently, S. aureus strains resistant to meticillin (MRSA) have become established within both communities. We isolated 314 isolates of MRSA from hospitalized patients in a referral hospital (HA isolates) and 268 isolates from its outpatient clinic (CA isolates) in Tehran, Iran, between February 2008 and December 2010. These isolates were tested for their susceptibility to 17 antibiotics and typed using the PhPlate system. The diversity in the structures of staphylococcal cassette chromosome mec (SCCmec) elements and ccr types was also detected using a multiplex-PCR assay and isolates were examined for the presence of different classes of prophages. Whilst all isolates were resistant to penicillin, the HA isolates were significantly more resistant to all other antibiotics tested than the CA isolates. Isolates carrying only SCCmec type III and ccr type 3 were dominant (91%), but 20% of the CA isolates belonging to less prevalent types carried only SCCmec types IVa, c and ccr type 2. These isolates also carried pvl genes and contained SGA prophage type. Our results indicate that whilst the dominant clonal groups of HA- and CA-MRSA belong to SCCmec type III and carry ccr type 3 genes, several distinct but less prevalent types of CA-MRSA carrying SCCmec type IVa, c and type 2 ccr are also found in Tehran. These strains carry pvl genes and the SGA prophage type, a characteristic that might be used as a marker for detection of CA-MRSA in this country.