حمیدرضا حوری

Staphylococcus is a bacterium responsible for a wide range of diseases, from mild skin infections to lethal necrosis pneumonia. The aim of this study was to determine the virulence factors among methicillin resistant and sensitive strains isolated from clinical specimens of children referred to the pediatric medical center and also to be aware of their antibiotic resistance.
In the present study, 100 strains of Staphylococcus aureus, susceptible and resistant to methicillin, were collected during one year. First Biochemical tests were performed to detect Staphylococcus aureus bacteria. Then antibiotic susceptibility test was performed using antibiotic disks (MAST;England) according to CLSI guidelines. The presence of hlg, mecA, nuc and pvl genes was investigated by PCR method and sequenced.
30 samples (30%) were methicillin-resistant (MRSA) using the cefoxitin disk. The most susceptible to antibiotics, vancomycin with 100% and the highest resistance to antibiotics, penicillin with 98% were determined. The prevalence of hlg, mecA, and pvl genes was 30%, 95% and 6%, respectively.
The present study showed that vancomycin and cotrimoxazole antibiotics were the best effect against MRSA strains.

Aims and scope: Otitis media (OM) is a common disease among children. Various factors, including bacteria and viruses are the cause of OM. The most common bacterial pathogens that can cause OM are Streptococcus pneumoniae, Haemophilus influenzae, Moraxella catarrhalis and Streptococcus pyogenes. Recently, Alloiococcus otitidis is known as one of the causes of OM. For some reasons such as fastidious growth and difficulty in sampling, few studies have been completed on this bacterium. The aim of this study was comparison of culture and multiplex PCR in detection of fastidious bacterial pathogens associated with otitis media.
Material & In this descriptive studies, during a period of 5 month from March 2013 to July 2014, 50 middle ear discharge specimens were collected from patients suspected with otitis media in Amir-Alam Hospital. Samples were assessed by culture and multiplex PCR method.
In the study, 3 strains of Alloiococcus otitidis (6%), 3 strains of Haemophilus influenzae (6%) and 1 strain of Moraxella catarrhalis (2%) were isolated by culture. Also, by multiplex PCR method 25 Alloiococcus otitidis (50%), 28 Haemophilus influenzae (56%) and 11 Moraxella catarrhalis (22%) were detected in the samples.
Identifying fastidious bacteria with culture method is difficult, but multiplex PCR method is more accurate, faster and more sensitive of culture method and biochemical tests and can be done quickly.

Streptococcus pneumoniaeis is the most frequent cause of bacterial meningitis, community-acquired bacterial pneumonia and acute otitis media (AOM). Eighty percent of children have at least once diagnosed by the three years of age. This study was conducted to determine the frequency of patients with Streptococcus pneumoniaein diagnosed with acute middle ear infections and antibiotic susceptibility patterns of this microorganism.
Middle ear discharge specimens were collected from 60 patients with acute otitis media during a period of 8 months, at Amir Alam Hospital (Tehran). Specimens were assessed for Streptococcus pneumonia by microscopic examination and culture. The antibiotic susceptibility test was performed by Kirby-Bauer disk diffusion method according to CLSI (clinical and laboratory standard institute) criteria. Antibiotics included tetracycline,erythromycin,vancomycin,chloramphenicol, amoxycilinclavulanate,Rifampine, ,ciprofloxacin, Cefixime,Trimethoprim䫩. Identification and confirmation of isolates were performed by PCR and culture.
Thirty three/ 60 and 27/60 of specimen were belong to men and women, respectively. Eight/ 60 tested specimens were confirmed as Streptococcus pneumonia. The sensitivity of isolated Streptococcus pneumoniae to different antibiotics was tested and the results were as following: tetracycline (56%), erythromycin (67%), vancomycin (22%), chloramphenicol (56%), and amoxycilin clavulanate (22%), Rifampine (44.4%), ciprofloxacin (56%), Cefixime (100%) Trimethoprim䫩 (77.8%).
Streptococcus pneumonia is the main cause for AOM. According to the emergence of resistant strains of Streptococcus pneumonia to conventional antibiotic therapy, especially beta-lactam antibiotics and erythromycin, continuous surveillance is needed to determine full picture of antibiotic susceptibility in patients with AOM.

The rising trend of antibiotic resistance among A. baumannii strains has become a global concern. The most common mechanism of resistance is betalactamase production with genes transferring on mobile genetic elements such as plasmids. The aim of this study was to determine the frequency of blaNDM, blaGIM, blaAIM, blaDIM and blaVIM type genes among A. baumannii isolates from hospitalized patients in Tehran, Iran.
from May 2012 to July 2013, 108 A. baumannii strains were isolated from blood, wound, urine, sputum and respiratory tract of hospitalized patients in Loghman hakim and Milad hospitals. Antibiotic susceptibility tests were performed by Kirby-Bauer disc diffusion and broth microdilution methods according the CLSI guidelines. The frequency of MBL (Metallo-Beta-Lactamase) producers was evaluated by CDDT. The β-lactamases genes were detected by PCR method.
The resistance of A. baumannii isolates against tested antibiotics were as follows: 103 (95.4%) to ceftazidime, 108 (100%) to cefotaxime, 105 (95.7%) to cefepime, 99 (91.7%) to imipenem, 99 (91.7%) to meropenem, 87 (80.6%) to amikacin, 105 (97.2%) to piperacillin, 100 (92.6%) to ciprofloxacin, 103 (95.4%) to piperacillin/tazobactam, 44 (40.7%) to gentamicin, 106 (98.1%) to ampicillin/sulbactam, 106 (98.1%) to co-trimoxazole, 87 (80.6%) to tetracycline, and 1 (1.8%) to colistin. Using combined disk diffusion test, 86 (86.86%) were MBL producers. The prevalence of blaVIM-1 gene was 15 (17.44%) and other genes were not detected.
The prevalence of MBLs-producing A. baumannii strains detected in this study is a major concern and highlights the need for infection control measures such as antibiotic management protocols and rapid identification of resistant strains.