GABHS is one of the most common pathogen bacteria in human. These kinds of bacteria cause variety of diseases. In addition , they have the capacity to trigger the post infectious syndromes of the acute  rheumatic fever. To use the drugs of choice for streptococcal pharingitis  reduces the risk of subsequent rheumatic fever. In recent years, there have been claims of an increasing number of treatment failure with common drugs for GABHS infection and its believed that the antibiotic resistance may be cause, at least, some parts of these treatment failures.

In this study , 141 strains of GABHS were isolated from patients with streptococcal pharingitis.

All of the patients were among 7 to12 years. 56.7% of patients were female and 43.3% male. It shows that the percentage of erythromycin tolerant is 7.1%. Penicillin tolerant was not found. 96.5% of them were sensitive to penicillin G and 3.5% were intermediate.

UTI is the most common infection in all ages and urinary catheters especially long-term catheterization are important predisposing factors of UTI. Urinary catheters are used in different hospital wards as a complementary curative method for the patients who are undergone various surgical procedures, such as : cesarean, hysterectomy , laparotomy, etc and they who are unable to control their voided urine .

226 urine specimens were collected from 119 catheterized patients which had been hospitalized in seven wards of Razi and Golestan hospitals in Ahwas city . At least two urine specimens were collected from each patient , before and after the insertion of the catheter . All of the specimens were inoculated to suitable Media, after transportation to the Microbiology Lab . Isolated colonies were identified and their resistance patterns were
   determined by the standard disk diffusion method (Kirby –Bauer procedure ) to 8 different antibiotics.

38 cases (43.6%) out of 87 patients showed Bacteriuria in the end of catheterization . They had no bacteriuria symptoms or sign before the catheterization. The most cases(28.9%) of bacteriuria occured in 30-39 years group and the lowest cases (2.6 %) of them occured in 60-69 years group.    Out of 50 bacterial strains isolated from urine cultures , E.coil (with 17 cases )
   was the highest (34%) and Staphylococcus aureus , Klebsiella pneumoniae , Edwardsiella tarda , Enterobacter sakazakii (with 2% for each) were the lowest cases. E.coli, Enterobacter and Kl. rhinoscleromatis , showed the most resistance to Ampicillin, Penicillin , Cephalexin , and the lowest rate to Nalidixic acid, Gentamicin and Nitrofurantoin . Staphylococcus epidermidis
   isolates ,also,showed the most resistance (100%) to Penicillin and Ampicillin , and the lowest rate to Gentamicin (with 66.7%), Cotrimoxazol and Nitrofurantoin (with 50%) .

         The results of this study suggested that catheterization , especially long- term catheterization causes the rise of urinary infections and so it is
   recommended that urinary catheters be avoided whenever possible.

Nowadays, the multiple drug resistance and resistance to different antimicrobial are observed in a wide variety of bacteria. One of these agents is U.V. ray that sometimes used to sterilize the operation room space and utensils and gamma ray to sterilize some medical Instruments such as disposal syringes & cottons and etc. If resistance emerges against the above mentioned factor, fighting microbs by these factors will encounter more problems.

            Therefore, In this research the multiple resistance of pathogenic strains of S. aureus isolated from different infections were studied. The M.I.C and M.B.C to penicillins were determined, using dilution tube method and plate cultured respectively. The influence of U.V ray on the growth of bacteria under hood of laminator flow was measured by photon-meter, during different times (0, 30, 60, 120, 240 Sec) at intensity of radiation 0.25 J/m².S^-1. The study of gamma ray on the growth of these bacteria were done by Iridium 192 source projector sentinel 660 as a gamma ray generator. Gamma irradiation was used at the intensity of 20 Gy/min and with dose of 500, 750 and 1000 Gray. The statistical study of the results obtained in different experiments was processed using S.A.S software. The standard strains were used as control and comparison.

            In these results, the strains of S. aureus showed maximum and minimum of MIC = 0.125% - 65 µg/ml and MBC = 1-128 µg/ml, respectively. For the study of bacterial level of resistance to U.V. ray, The most important resistance strains to antibiotics have been selected. The mean number of the colonies grown in the culture medium area after 120 and 240 seconds of U.V. radiation were Log
   N/No = 21.8, 6.9 respectively in the strain of Staphylococcus.

            Resistance of isolated strains of S. aureus in this research was higher than those of standard strains.

Introduction & Objective: Acinetobacter baumannii is an important nosocomial pathogen all over the world and has emerged as a threat to public health which also exhibit multiple-antibiotic resistance. Studies of antibiotic resistance mechanism in these bacteria have demonstrated the presence of specific antimicrobial resistance genes located mainly in integrons. The purpose of this study was to search for the presence of the class 2 integron in strains of A. baumannii found in Tehran-Iran and the relationship between the presence of this integron and the antimicrobial susceptibility patterns.

Material & Methods: This cross sectional study was performed in three main hospitals in Tehran on 500 clinical samples during a 10 month period (March to December 2010). In laboratory, after identifying the species of A. baumannii by using culture and biochemical methods, disc diffusion method according to CLSI guidelines was performed to determine the sensitivity of 50 isolates of these bacteria to 13 antibiotics. Polymerase chain reaction (PCR) was performed for the detection of integron class 2 by Int2F/R primers. Eventually correlation of multi-drug resistance and existence of integron class II were studied.

Results: Of these 500 samples, 50(71.5%) strains of A. baumannii, 12(17%) A. lwoffii strains and 8 (11.5) other Acinetobacter species were isolated. The most common resistance detected among 50 isolates was to Cefepime, Ceftazidime, Aztreonam, Norfloxacin, Ciprofloxacin, Ofloxacin, and Amikacin. Also, less resistance was observed to imipenem, Gentamycin, Ampicillin- sulbactam, Piperacillin-Tazobactam. Meropenem and Tobramycin were considered as effective drugs in this study. Class 2 integrons were found in 41 (82%) of the 50 isolates of A. baumannii. Moreover, a significant correlation between integron class2 and resistance to antibiotics of Cefepime, Ceftazidime, Aztreonam, Norfloxacin, Ciprofloxacin, Ofloxacin, and Amikacin were observed.

Conclusion: Our findings indicates that class 2 integron are widely spreads among A. baumannii isolated in Tehran, Iran and plays an important role in multidrug resistance in these bacteria. Therefore, monitoring drug resistance due to integron class 2 by PCR, in protocols of infection control due to multidrug-resistant A. baumannii in hospitals of Tehran is important.

Introduction & Objective: Staphylococcus aureus has been known as one of the most common nosocomial pathogens worldwide. Methicillin-resistant S.aureus is one of the most important nosocomial pathogens with increasing global prevalence in the recent 3 decades. The aim of this study was to assess the prevalence of nasal carriage of this organism in medical students because they, being potential carriers, can be considered as one of the infection sources.

Materials & Methods: In a cross-sectional study nasal swabs were collected from 258 medical students (103 males and 155 females) including: 116 preclinical, 92 clinical students and 50 residents. Samples were cultured on blood agar. S. aureus isolates were further analyzed for antibiotic resistance with agar disk diffusion method. Each person was questioned for sex, grade, recent disease and drug history and family members’ employment in hospital.

Results: 25.2% of 258 students were positive for nasal carriage of S. aureus. There was no significant difference among sexes or grades in carrier prevalence. Most isolates were resistant to penicillin (92.3%), and 47.7% were methicillin-resistant. Most methicillin-resistant strains were isolated from clinical students (87%), and most vancomycine-resistant isolates were found in residents (30.8%).

Conclusion: The rate of nasal carriage of S.aureus in medical students was similar to general population and hospital personnel but the rate of MRSA and vancomycin-resistant S.aureus carriers in the students is more than hospital personnel.