Investigation of biofilm formation among methicillin-resistant Staphylococcus aureus isolated from children

Background: The aim of the present study was to investigate biofilm formation among Methicillin-resistant Staphylococcus aureus (MRSA) isolated from children referring to a pediatric hospital in Tehran. Methods: In total, 98 MRSA isolates were collected from children referring to a pediatric hospital during 2014 - 2015. All the isolates were confirmed to be MRSA using PCR amplification of the mecA gene. The antibiotic susceptibility patterns of the isolates were determined using the Kirby-Bauer disk-diffusion and E-test methods. In order to assess the ability of biofilm formation among the isolates, Congo red agar (CRA) and Microtiter Plate (Mtp) methods were used. Results: All the isolates were found to be susceptible to linezolid and vancomycin and, likewise, the majority was susceptible to minocycline and rifampicin. CRA and Mtp methods showed that 81.6 and 63.3 of the MRSA isolates, respectively, were biofilm producers. Conclusions: The early identification of S. aureus and detection of biofilm formation by the Mtp method are essential steps towards the prevention of the most serious nosocomial infections. © 2017, Archives of Pediatric Infectious Diseases

Investigation of biofilm formation among methicillin-resistant Staphylococcus aureus isolated from children

Background: The aim of the present study was to investigate biofilm formation among Methicillin-resistant Staphylococcus aureus (MRSA) isolated from children referring to a pediatric hospital in Tehran. Methods: In total, 98 MRSA isolates were collected from children referring to a pediatric hospital during 2014 - 2015. All the isolates were confirmed to be MRSA using PCR amplification of the mecA gene. The antibiotic susceptibility patterns of the isolates were determined using the Kirby-Bauer disk-diffusion and E-test methods. In order to assess the ability of biofilm formation among the isolates, Congo red agar (CRA) and Microtiter Plate (Mtp) methods were used. Results: All the isolates were found to be susceptible to linezolid and vancomycin and, likewise, the majority was susceptible to minocycline and rifampicin. CRA and Mtp methods showed that 81.6 and 63.3 of the MRSA isolates, respectively, were biofilm producers. Conclusions: The early identification of S. aureus and detection of biofilm formation by the Mtp method are essential steps towards the prevention of the most serious nosocomial infections. © 2017, Archives of Pediatric Infectious Diseases

Distribution of the most prevalent spa types among clinical isolates of methicillin-resistant and -susceptible Staphylococcus aureus around the world: A review

Background: Staphylococcus aureus, a leading cause of community-acquired and nosocomial infections, remains a major health problem worldwide. Molecular typing methods, such as spa typing, are vital for the control and, when typing can be made more timely, prevention of S. aureus spread around healthcare settings. The current study aims to review the literature to report the most common clinical spa types around the world, which is important for epidemiological surveys and nosocomial infection control policies. Methods: A search via PubMed, Google Scholar, Web of Science, Embase, the Cochrane library, and Scopus was conducted for original articles reporting the most prevalent spa types among S. aureus isolates. The search terms were "Staphylococcus aureus, spa typing." Results: The most prevalent spa types were t032, t008 and t002 in Europe; t037 and t002 in Asia; t008, t002, and t242 in America; t037, t084, and t064 in Africa; and t020 in Australia. In Europe, all the isolates related to spa type t032 were MRSA. In addition, spa type t037 in Africa and t037and t437 in Australia also consisted exclusively of MRSA isolates. Given the fact that more than 95 of the papers we studied originated in the past decade there was no option to study the dynamics of regional clone emergence. Conclusion: This review documents the presence of the most prevalent spa types in countries, continents and worldwide and shows big local differences in clonal distribution. © 2018 Asadollahi, Farahani, Mirzaii, Khoramrooz, van Belkum, Asadollahi, Dadashi and Darban-Sarokhalil

Genotypic characterization of Staphylococcus aureus isolated from a burn centre by using agr, spa and SCCmec typing methods

Infections caused by Staphylococcus aureus remain a major global healthcare problem. We aimed to find the common lineages of S. aureus strains circulating in a burn hospital in Tehran. A total of 167 isolates of S. aureus obtained from patients, healthcare workers (HCWs) and environment in Shahid Motahari burn hospital were genotyped by using spa, agr and staphylococcal cassette chromosome mec (SCCmec) typing methods. Antimicrobial susceptibility testing was performed by using the disc diffusion method. The frequency of methicillin-resistant S. aureus (MRSA) was 64.7 (n = 108), with distribution frequencies among patient, HCW and surface isolates of 64.2 (n = 79), 50 (n = 7) and 73.3 (n = 22), respectively. SCCmec type III (75, n = 81) was found to be the most frequent SCCmec type among MRSA isolates, followed by SCCmec type I (20.4, n = 22) and SCCmec type IV (1.8, n = 2). The remaining MRSA isolates (2.8, n = 3) were nontypeable by this method. About 78.4 (n = 131), 10.2 (n = 17) and 4.8 (n = 8) of all isolates were characterized as agr types I, II and III, respectively, and the other isolates (6.6) were nontypeable. spa types t030 and t037 constituted the first and second most predominant spa types found in 56.4 (n = 57) and 25.6 (n = 26) of isolates, respectively. We also report here a novel spa type, t16471. The most prevalent genotypes of the isolates found among patient, surface and HCW samples were SCCmec type III/t030, t037/agr type I. Continuous tracking of epidemic isolates and better hospital infection control policies are recommended to efficiently prevent the spread of bacteria to inpatients. © 201

Genotypic characterization of Staphylococcus aureus isolated from a burn centre by using agr, spa and SCCmec typing methods

Infections caused by Staphylococcus aureus remain a major global healthcare problem. We aimed to find the common lineages of S. aureus strains circulating in a burn hospital in Tehran. A total of 167 isolates of S. aureus obtained from patients, healthcare workers (HCWs) and environment in Shahid Motahari burn hospital were genotyped by using spa, agr and staphylococcal cassette chromosome mec (SCCmec) typing methods. Antimicrobial susceptibility testing was performed by using the disc diffusion method. The frequency of methicillin-resistant S. aureus (MRSA) was 64.7% (n = 108), with distribution frequencies among patient, HCW and surface isolates of 64.2% (n = 79), 50% (n = 7) and 73.3% (n = 22), respectively. SCCmec type III (75%, n = 81) was found to be the most frequent SCCmec type among MRSA isolates, followed by SCCmec type I (20.4%, n = 22) and SCCmec type IV (1.8%, n = 2). The remaining MRSA isolates (2.8%, n = 3) were nontypeable by this method. About 78.4% (n = 131), 10.2% (n = 17) and 4.8% (n = 8) of all isolates were characterized as agr types I, II and III, respectively, and the other isolates (6.6%) were nontypeable. spa types t030 and t037 constituted the first and second most predominant spa types found in 56.4% (n = 57) and 25.6% (n = 26) of isolates, respectively. We also report here a novel spa type, t16471. The most prevalent genotypes of the isolates found among patient, surface and HCW samples were SCCmec type III/t030, t037/agr type I. Continuous tracking of epidemic isolates and better hospital infection control policies are recommended to efficiently prevent the spread of bacteria to inpatients. Keywords: agr typing, Iran, MRSA, SCCmec typing, spa typin

Disruption prediction with artificial intelligence techniques in tokamak plasmas

In nuclear fusion reactors, plasmas are heated to very high temperatures of more than 100 million kelvin and, in so-called tokamaks, they are confined by magnetic fields in the shape of a torus. Light nuclei, such as deuterium and tritium, undergo a fusion reaction that releases energy, making fusion a promising option for a sustainable and clean energy source. Tokamak plasmas, however, are prone to disruptions as a result of a sudden collapse of the system terminating the fusion reactions. As disruptions lead to an abrupt loss of confinement, they can cause irreversible damage to present-day fusion devices and are expected to have a more devastating effect in future devices. Disruptions expected in the next-generation tokamak, ITER, for example, could cause electromagnetic forces larger than the weight of an Airbus A380. Furthermore, the thermal loads in such an event could exceed the melting threshold of the most resistant state-of-the-art materials by more than an order of magnitude. To prevent disruptions or at least mitigate their detrimental effects, empirical models obtained with artificial intelligence methods, of which an overview is given here, are commonly employed to predict their occurrence—and ideally give enough time to introduce counteracting measures