Tehran University Medical Journal

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Methicillin resistant staphylococcus aureus (MRSA) is a predominantly nosocomial pathogen which its prevalence has increased worldwide over the past three decades.
Materials and Methods: This is a descriptive cross-sectional study. The following study is designed for determination of prevalence of MRSA infection through measurement of MICs of S. aureus isolates in Imam Khomeini Hospital (a teaching hospital) from November 2001 to January 2003. A total number of 402 specimens were isolated and specified as S. aureus by Imam Khomeini microbiology lab. Demographic and clinical data and results of MIC were analysed by Epilnfo 6 software.
Results: During the study, staphylococcus aureus was isolated from 402 patients that 187 (46.5%) of isolates were MRSA and 215 (53.5%) were MSSA. Of 402 patients, 254 (63.2%) were male and 148 (36.8%) were female. The difference of the prevalence of MRSA between males and females was not statistically significant (p= 0.09). The difference in mean age in MRSA and MSSA groups was not statistically significant (p= 0.55). In the age group of < 1 month, the prevalence of MRSA infection was significantly higher than other groups (P= 0.01).
Conclusion: In this study, the prevalence of MRSA infection was increased, statistically significant in the presence of such factors as sepsis, longer duration of hospitalization, hospital- acquired infection, history of invasive procedure, history of antimicrobials used in the past 3 months and type of administered antimicrobial (s), history of hospitalization in the preceding year, certain underlying diseases, type of admission ward, type of infection, type of specimen and type of administered antimicrobials for treatment. Surprisingly, the prevalence of MRSA infection in IV drug user group was low that was statistically significant (p< 0.0001). In this study, there was no statistically significant difference in outcome between MRSA infected and MSSA infected patients. Based on results of this study, prevalence of infections due MRSA in this hospital are high, therefore addition to diagnosis of risk factors of MRSA infections, application of standard infection control practices should be done for limitation of these infections.

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Background: Staphylococci as a micro-organism, has the most importance to cause nosocomial infections, particularly in patients with indwelling catheters or other medical devices. Unfortunately 90% of Staphylococci isolated from the nosocomial infections are resistant to methicillin, and methicillin resistance strains are also resistant to a wide range of antimicrobial drugs, therefore detecting of these strains are valuable to eradicate the infection elements. Despite guidelines published by the national committee for clinical laboratory standards (NCCLS) for testing of susceptibility to methicillin for Staphylococci, the phenotypic method for detecting methicillin resistance remains controversial. Therefore, the genetic assays have been used to detect antimicrobial susceptibility of Staphylococci to methicillin.
Materials and Methods: Resistance to methicillin is coded by mec A gene in staphylococcus, and this gen must be detected in genetic assays. In this study 155 clinical staphylococcal isolates (70 coagulase- negative staphylococcus and 85 coagulase- Positive staphylococci) were evaluated for susceptibility to methicillin by using disk diffusion method.
ResuIts&Conclusion: Methicillin resistance was shown in 62 coagulase- negative staphylococcus (72.9%) and 27 coagulas positive staphylococcus (38.6%) but 63 coagulase negative Staphylococci (74%) and 28 coagulase positive isolates with mec a gene associated resistance were detected by PCR method. The results of this test were compared to the results for mec A gene detection by PCR test as a gold standard. The sensitivity, specifity and accuracy of the disk diffusion test for coagulase-negative staphylococcus were 96.8%, 95.45% and 96.47% and for coagulase positive staphylococci were 98.43%, 95.45% and 98.32% respectively.

 

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Background: Staphylococcus aureus is one of the most common causes of nosocomial infections with high morbidity and mortality rate. Traditionally, methicillin resistant staphylococcus aureus has been considered a major nosocomial pathogen in healthcare facilities, but in the past decade, it has been observed emerging in the community as well. Informations regarding hospital microbial colonization could be an important step for prevention of nosocomial infections. Our objective was clarifying the prevalence of methicillin resistant and vancomycin resistant staphylococcus aureus colonization in nasopharynx.
Methods: A descriptive cross sectional study was carried on 106 patients and nursing staff of surgery and hemodialysis wards in Amir-Alam hospital from April 2005 to July 2005. The samples were collected from nasal region of cases using cotton swab by two experienced technician and were sent to laboratory for culture and antibiogram.
Results: Twenty six (29.5%) out of 106 cases were nasopharyngeal carriers of staphylococcus aureus. Eight cases (7.5%) had methicillin resistant staphylococcus aureus. The most frequent colonization rate was seen in hemodialysis nursing staff and in all of them methicillin resistant staphylococcus aureus was reported. Carrier rates in hemodialysis patients were twice compared to surgery ward patients. The interesting point was that no sample of vancomycin resistant staphylococcus aureus was isolated.
Conclusion: Prevalence of methicillin resistant staphylococcus aureus colonization seems to be increased therefore proper management for controlling this problem is mandatory. The results of the present study suggest that the prevalence of methicillin resistant staphylococcus aureus infections is higher than was expected in Iran and vigorous preventive strategies should therefore be taken to stop the growth of this major health problem.

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Background: Diabetic foot infections a common complication of diabetes. Staphylococcus aureus is most common pathogen associated with diabetic foot infection. Frequency of methicillin-resistant Staphylococcus aureus (MRSA) associated with diabetic foot infection at other country is 15-30% and important cause at hospital acquired infection. The aim of this study was to evaluate the prevalence of pathogenic organisms and the prevalence and contributing factors of MRSA in patients with diabetic foot infection. Methods: A cross-sectional study from 70 diabetic foot infection at Imam Khomeini Hospital, Tehran, Iran from March 2013 to September 2014. A retrospective analysis of wound swabs taken from infected foot ulcers in diabetic patient, selected from an outpatient diabetic foot. Swabs were used to obtain tissue fluid from the base after debriding the ulcer with a sterile scalpel. Sixty patients with positive wound swabs were included. Size of ulcer and ulcer grade were measured in all patients. Results: A total of 61 microorganisms were isolated. The mean number of isolate was 0/87. Corynebacterium spp were the sole pathogen in three cases than taked into normal flora. There wasn’t significant P-value between demographic subjects and MRSA frequency. In this study, P= 0/05, CI:95% were considered statistically significant. Gram-positive aerobic bacteria were the most common micro-organism isolated (52.54%) followed by gram-negative aerobic bacteria (44.26%). among the gram-positive aerobic organisms, Staphylococcus aureus was found most frequently and 10% were MRSA that confirmed by E-test. There wasn’t significantly different in measurement of the MRSA positive patients compared to MRSA negative patients (P> 0.05). Conclusion: In this study, MRSA prevalence was similar to other Asian studies and different from west countries study. There wasn't significant difference between gram-positive and gram-negative microorganisms that look out to change of microbiological profile in diabetic foot infections and creation multi-drug resistant bacteria. MRSA infections and other multi drug resistant organisms is a serious problem and increasing problem in diabetic foot infections. Further studies are required to assess the need for antibiotics in treating foot ulcers in diabetes and to assess the optimal therapeutic management.

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Background: Staphylococcus aureus is a gram positive coccus which is able to cause different kinds of infection in certain condition. The function of this bacteria is to provide the conditions for the invasion of it to the host with the secretion of different sorts of toxins such as Staphylococcus aureus enterotoxin, including important virulence factors that super antigens are all factors digestive inconvenience. Staphylococcus aureus enterotoxin-secreting toxins such conditions provides invasion of host genes. There are different types of SE, but type A enterotoxin (SEA) and type B enterotoxin (SEB) are the most important types. Therefore, in this study, the prevalence of Staphylococcus aureus toxin-producing enterotoxin genes (SEB, SEA) in clinical strains isolated from patients in teaching hospitals of Shahrekord city, Iran, were studied.

Methods: This cross-sectional and descriptive study, which was conducted from May 2014 to December 2014. A hundred and ten isolates of Staphylococcus aureus from patients collected over a period of 8 months and were first identified using standard biochemical methods and laboratory. Using standard methods and laboratory tests were identified and compared with the antibiotic oxacillin minimum inhibitory concentration were determined by broth micro dilution, and then they were assessed by polymerase chain reaction (PCR) technique.

Results: The results indicated that, 110 samples of dairy products infected by Staphylococcus aureus were detected. Two cases (1.8%) of these infected samples were carrying both enterotoxin A and enterotoxin B genes. The frequencies of enterotoxin A genes were twenty-six cases (23/6%) and The frequencies of enterotoxin B genes were two cases (1/8%), respectively.

Conclusion: The detection of enterotoxin A and enterotoxin B genes, shows the most important role they have in bringing about superinfection. The detection of enterotoxin A and B genes, shows the most important role they have in bringing about superinfection. Enterotoxins SEA and SEB are heat stable; therefore heating has no effect on dairy products contaminated by enterotoxins and gastritis may occur in a short period of time. As PCR is a rapid, sensitive, specific and inexpensive method, we suggest that it can be replaced to traditionally assays for detecting Staphylococcus aureus enterotoxin.

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Background: Today, Methicillin-Resistant Staphylococcus Aureus (MRSA) has become one of the public health concerns due to its resistance to antimicrobial drugs, and this problem makes treating patients with infections caused by this bacterium difficult. Infections caused by methicillin-resistant Staphylococcus aureus (MRSA) strains are pervasive in both community and hospital settings, primarily attributable to Staphylococcus aureus' capacity to colonize areas like the nose or skin. In this study, with the aim of comparing phenotypic (disc diffusion method) and genotypic (PCR) methods, to detect methicillin-resistant Staphylococcus aureus isolated from patients of hospitals under supervision of Tehran university of medical sciences, and also detection of nor A, that is the one of the most important genes in efflux pump cluster genes.
Methods: The present research was a cross- sectional study that was conducted from February 2022 to September 2023. In this research, 43 isolated strains of Staphylococcus aureus from wound discharge and blood samples, were collected from different departments of Tehran hospitals and had submitted to the research laboratory of the school of allied medical sciences in Tehran university of medical sciences. After identifying the strains, the resistance of the isolates to 14 types of antibiotics was checked by disk diffusion method.