Phenotypic methods of greater accuracy to detect the mecA gene product for the recognition of MRSA in resource constraint settings

ObjectiveTo evaluate the detection of methicillin resistant Staphylococcus aureus (MRSA) and analyze the performance of Mastalex MRSA (Mast, UK).MethodsTwo hundred and ten Staphylococcus aureus (S. aureus) strains were isolated from different clinical samples and were tested for methicillin resistance by Oxacillin (1 μg) and Cefoxitin (30 μg) disc diffusion, oxacillin agar screen, and minimum inhibitory concentration of oxacillin and cefoxitin. S. aureus isolates were grown on the blood agar and mannitol salt agar with (2 mg/L) and without oxacillin for the analysis of Mastalex MRSA.ResultsOut of 210 S. aureus strains tested, 103 strains were detected as methicillin resistant by Cefoxitin disk diffusion, Cefoxitin minimal inhibitory concentration (MIC) and Mastalex MRSA test. Whereas oxacillin disc diffusion and oxacillin agar screen detected 91 and 97 MRSA respectively. The Cefoxitin MIC test performance was equivalent to Cefoxitin disc diffusion. 103 (100%) strains grown on blood agar without and with oxacillin, and 76 (74%) and 93 (91%) strains grown on mannitol salt agar without and with oxacillin shown positive agglutination with Mastalex MRSA test respectively.ConclusionsThe cefoxitin disk diffusion/Mastalex MRSA is very suitable for detection of MRSA and the tests can be an alternative to PCR for detection of MRSA in resource constraint settings. Mastalex test would be particularly useful when confirmation of resistance is urgently required.     

Determining of antibiotic resistance profile in Staphylococcus aureus isolates

ObjectiveTo determine the pattern of antibiotic resistance among Staphylococcus aureus (S. aureus) isolates from clinical specimens and to identify community-acquired methicillin-resistant Staphylococcus aureus (CA-MRSA) in specimens that have been collected from patients referring to one of the hospitals of Ahvaz.MethodsS. aureus isolates from a hospital in Ahvaz were screened for resistance to various antibiotics including methicillin. The susceptibility of the isolates was determined by Kirby-Bauer disc diffusion method. The MRSA was also treated with ethidium bromide to find the origin of resistance.ResultsAmong the bacterial isolates, all of 11 S. aureus were resistant to methicillin and cefixime, 2 were resistant to ciprofloxacine, 6 were resistant to tetracycline and the reminder were sensitive or intermediate to other antibiotics. The treated isolates were reminded resistant to methicillin and this suggested that the plasmid was not the origin of resistance in these isolates.ConclusionsThese results showed that infection due to MRSA is widespread in Ahvaz and with respect to the spread of vancomycin resistance among MRSA and appearance of overwhelming infections. It is necessary to identify continuously the profile of antibiotic resistance among S. aureus isolates in other regions and finding appropriate antibiotic for infection control and eradication.     

Epidemiological and molecular characterization of community and hospital acquired Staphylococcus aureus strains prevailing in Shenyang,Northeastern China

In order to obtain adequate information for the treatment of methicillin resistant Staphylococcus aureus (MRSA) infections, it is crucial to identify trends in epidemiological and antimicrobial resistance patterns of local S. aureus strains. Community and hospital acquired S. aureus isolates (n = 202) were characterized using staphylococcal cassette chromosome mec (SCCmec) typing, pulse field gel electrophoresis (PFGE) analysis, spa typing and minimal inhibitory concentration (MIC) determination. The prevalence of the Panton-Valentine leukocidine (pvl) and several antibiotic resistance genes among the isolates were also detected by PCR. All of the S. aureus isolates were susceptible to vancomycin, daptomycin and linezolid. Three hospital isolates were resistant to teicoplanin while 14 showed intermediate resistance to teicoplanin. The resistance patterns of community-acquired MRSA (CA-MRSA) isolates to other antimicrobials were similar to those of hospital-acquired MRSA (HA-MRSA) isolates except for clindamycin and gentamicin. There was excellent correlation between phenotypes and genotypes in the determination of S. aureus resistance to erythromycin, gentamicin, and tetracycline. The SCCmec type II and SCCmec type IV were the predominant types detected in hospital and community isolates, respectively. The most frequently encountered spa types were t002 and t030 both in HA- and CA-MRSA isolates. Pulsotype A was the most predominant pulsotype identified among the isolates tested, followed by pulsotype B. Seventy-two hospital isolates (19 HA-MRSA and 53 HA-MSSA) and 10 CA-MRSA were positive for the pvl gene. This study shows that the combination of susceptibility testing and various molecular methods has provided useful information on the antibiotic resistance and molecular diversity of S. aureus in a specific region of China. The high proportion of pvl positive MSSA and MRSA isolates observed in this study indicates that adequate measures are needed to curtail the spread of those MRSA and MSSA clones prevailing both in hospital and the community.     

我院45株金黄色葡萄球菌临床分布及消毒剂耐药基因qacA的检测

目的 分析我院耐甲氧西林金黄色葡萄球菌（MRSA）临床分布及耐消毒剂基因qacA检测情况，为合理使用消毒剂、减少院内感染提供依据。方法收集2007年1月-2008年6月分离自河北医科大学第一医院住院患者的blRSA45株，采用PCR方法对其耐消毒剂基因qacA进行检测。结果45株MRSA中18株（40％）检出qacA基因，其中呼吸内科、烧伤科标本检出率较高，分别为13％、16％。结论我院呼吸内科和烧伤科等科室MRSA分离率及qacA基因阳性率较高，此为常用消毒剂耐药的主要机制；临床应根据患者标本qacA检测情况合理选用消毒剂。     

Surveillance of infection status of drug resistant Staphylococcus aureus in an Indian teaching hospital

Objective

To access nosocomial and community accounts of multidrug resistant strains of Staphylococcus aureus (S. aureus) isolated by surveillance in a teaching hospital, over a period of 30 months.

Methods

Clinical samples from nosocomial sources, i.e., wards and cabins, intensive care unit (ICU) and neonatal intensive care unit (NICU) sources, as well as community or outpatient department (OPD) sources of a hospital were used for isolating strains of S. aureus resistant to methicillin/oxacillin and vancomycin, over a period, November 2009-April 2012.

Results

Of a total of 1 507 S. aureus isolates, 485 strains from community and 1 022 isolates were from nosocomial sources; Out of 485 (100%) OPD S. aureus isolates, 390 (80.41%) were MRSA strains. Similarly, from wards and cabins of 564 (100%) isolates, 461 (81.73%) strains were MRSA; whereas of 458 (100%) isolates obtained from ICU and NICU, 363 (79.25%) strains were MRSA. It was ascertained with χ²-tests of independence that MRSA strains were equally distributed in “community” or “wards and cabins” or “ICU and NICU” sources, alike rest other drug-resistant S. aureus strains. Antibiotic sensitivity patterns of isolated strains with 16 antibiotics were ascertained. Out of 390 (100%) MRSA strains isolated from OPD, 80 (20.51%) were vancomycin resistant (VRSA) and 173 (44.35%) strains were moderately sensitive to vancomycin or called, vancomycin intermediate strains (VISA). Similarly, from nosocomial sources, out of 461 (100%) MRSA isolates obtained from wards and cabins, 110 (23.86%) strains were VRSA and 208 (45.11%) were VISA strains, whereas out of 363 MRSA isolates obtained from ICU and NICU, 61 (16.8%) VRSA strains and 164 (45.17%) VISA strains were found. A progressive increase of percent values of drug resistance to 16 antibiotics used for antibiotic profiling revealed its subtle infection dynamics.

Conclusions

This study revealed the appalling state of occurrence of MRSA and VRSA in a resource-limited setting. A progressive increase of percent values of drug resistance to 16 antibiotics used revealed its subtle infection dynamics.     

Prevalence of phenotypic resistance of Staphylococcus aureus isolates to macrolide,lincosamide, streptogramin B,ketolid and linezolid antibiotics in Turkey

The incidence of drug-resistant pathogens differs greatly between countries according to differences in the usage of antibiotics. The purpose of this study was to investigate the phenotypic resistance of 321 methicillin resistance Staphylococcus aureus (MRSA) and 195 methicillin susceptible S. aureus (MSSA) in a total of 516 S. aureus strains to macrolide, lincosamide, streptogramin B (MLS_B), ketolid, and linezolid. Disk diffusion method was applied to determine MLS_B phenotype and susceptibility to different antibiotic agents. It was found that 54.6% of the isolates were resistant to erythromycin (ERSA), 48% to clindamycin, 55% to azithromycin, 58.7% to spiramycin, 34.7% to telithromycin, and 0.4% to quinupristin-dalfopristin, respectively. No strain resistant to linezolid was found. The prevalence of constitutive (cMLS_B), inducible (IMLS_B), and macrolides and type B streptogramins (M/MS_B) among ERSA isolates (237 MRSA, 45 MSSA) was 69.6%, 18.2%, and 12.2% in MRSA and 28.9%, 40%, and 31.1% in MSSA, respectively. In conclusions, the prevalence of cMLS_B was predominant in MRSA; while in MSSA strains, iMLS_B and M/MS_B phenotype were more higher than cMLS_B phenotype resistance. The resistance to quinupristindalfopristin was very low, and linezolid was considered as the most effective antibiotic against all S.aureus strains.     

Methicillin-resistant Staphylococcus aureus prevalence: Current susceptibility patterns in Trinidad

Background  

Methicillin-resistant Staphylococcus aureus (MRSA) has become one of the most widespread causes of nosocomial infections worldwide. Recently, reports have emerged that S. aureus strains recovered from community-acquired infections are also methicillin-resistant. This study was undertaken to analyze the prevalence of methicillin resistance among isolates at a regional hospital in Trinidad, and document the current resistance profile of MRSA and methicillin-sensitive Staphylococcus aureus (MSSA) to the commonly used anti-staphylococcal agents.     

Community-acquired methicillin-resistant Staphylococcus aureus carrying SCCmec type IV and V isolated from healthy children attending public daycares in northeastern Brazil

Nasal colonization with methicillin-resistant Staphylococcus aureus (MRSA) have increasingly been reported in healthy communities. This study aimed to assess the rate of S. aureus in general and MRSA in particular from nasal secretion of children in daycare centers in Vitória da Conquista, Brazil. The isolates were identified based on morphology, biochemical tests and by PCR. Detection of virulence genes, biofilm production, and susceptibility test by disk diffusion agar were performed. MRSA isolates were characterized by spa, SCCmec, and multilocus sequence typing (MLST). S. aureus were recovered from 70 (47.3%) of 148 children. Among the 11 MRSA strains (15.7%), two SCCmec types (IV and V) were detected. MLST identified four STs related to three clonal complexes (CC): 5, 45, and 398. Four spa types were found circulating in this setting. Resistance of S. aureus isolates to ampicillin, erythromycin, ciprofloxacin, clindamycin, and tetracycline was 80%, 32.8%, 7.1%, 7.1% and 4.3%, respectively. One isolate presented intermediate resistance to vancomycin detected by Etest methodology. All strains were biofilm producers. The virulence genes seb, sec, spa, and pvl were detected in some isolates. This study revealed a high rate of children carrying MRSA among healthy attendees in daycare centers in Vitória da Conquista, Brazil.     

Distribution of genes encoding resistance to aminoglycoside modifying enzymes in methicillin-resistant Staphylococcus aureus (MRSA) strains

Today Methicillin-Resistant Staphylococcus aureus (MRSA) have acquired multiple resistance to a wide range of antibiotics including aminoglycosides. So, this study was aimed to investigate the rate of aminoglycoside resistance and the frequency of aminoglycoside resistance mediated genes of aac(Ia)-2, aph(3)-IIIa and ant(4′)-Ia among MRSA strains. A total of 467 staphylococci isolates were collected from various clinical samples. S. aureus strains were identified by standard culture and identification criteria and investigating of presence of 16S rRNA and nuc genes. Cefoxitin disk diffusion, and oxacillin-salt agar screening methods were used to detect the MRSA strains with subsequent molecular identification for the presence of mecA gene. Antibiotic susceptibility of MRSA strains against aminoglycoside antibiotics was evaluated by using agar disk diffusion method. Multiplex PCR for the presence of aac(Ia)-2, aph(3)-IIIa and ant(4′)-Ia encoding genes for aminoglycosides were performed for MRSA strains. From total staphylococci tested isolates, 262 (56.1%) were identified as S. aureus, of which 161 (61.45%) were detected as MRSA and all comprised mecA gene. The resistance pattern of MRSA strains to aminoglycoside antibiotics were: gentamicin 136 (84.5%); amikacin 125 (77.6%); kanamycin 139 (86.3%); tobramycin 132 (82%); and neomycin 155 (96.3%). The frequency of aac(Ia)-2, aph(3)-IIIa, and ant(4′)-Ia genes among MRSA strains, were 64%, 42% and 11.8% respectively. In conclusion, as MRSA strains are of great concern in human infections, the results of present study could provide a useful resource for health sectors for choosing appropriate antibiotics for the effective treatment of infections due to MRSA strains.     

Molecular characteristics and virulence gene profiles of Staphylococcus aureus causing bloodstream infection

Background

The rate of methicillin-resistant Staphylococcus aureus (MRSA) among the total of S. aureus isolates decreased to 35.3% in 2017 in China. It is unclear whether the molecular characteristics of S. aureus isolates have changed as the rate decreased.

Actividad in vitro de la combinación de ceftarolina con otros antimicrobianos activos frente a Staphylococcus spp

IntroductionWe evaluated the in vitro activity of the combination of ceftaroline with daptomycin, linezolid and vancomycin against methicillin-resistant Staphylococcus aureus and coagulase-negative Staphylococcus (CNS).Material and methodsWe analysed 70 staphylococcal strains (31 S. aureus and 39 CNS) with the Etest using the MIC:MIC ratio method and calculation of fractional inhibitory concentration indexes.ResultsThe combination of ceftaroline with daptomycin showed an additive effect (53.2%) and synergy (6.6%) against methicillin-susceptible S. aureus, and an additive effect (81.2%) against methicillin-resistant S. aureus (MRSA). This combination also showed an additive effect against 33% of linezolid-susceptible CNS and was not synergistic against linezolid-resistant CNS. The combination of ceftaroline with vancomycin was synergistic (87%) and ceftaroline with linezolid was additive (37%) against MRSA.ConclusionsThe combinations of ceftaroline with daptomycin, vancomycin or linezolid showed additive and/or synergistic effects against methicillin-resistant Staphylococcus.     

MIC and serum bactericidal activity of clindamycin against methicillin-resistant and -sensitive Staphylococci

Summary Six volunteers were given 600 mg clindamycin intravenously to investigate the serum bactericidal activity (SBA) against 50 methicillin susceptible (MSSA) and 50 methicillin resistantStaphylococcus aureus (MRSA) strains. Minimal inhibitory concentrations (MIC) against MSSA, MRSA and 50 methicillin resistant strains ofStaphylococcus epidermidis (MRSE), of which 50% were slime-producing, were determined. SBA of clindamycin against MSSA and MRSA was equally high (mean reciprocal SBA titer against MSSAvs MRSA 1h after application was 13.0vs 13.45), although MICs against MRSA were markedly higher than against MSSA (MIC 90 of MRSAvs MSSA: 0.06vs>32 mg/l). There was no difference in MICs between slime- and non-slime-producing MRSE.

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MHK und Serumbakterizidie von Clindamycin gegen methicillinresistente und -empfindliche Staphylokokken

Zusammenfassung In dieser Studie wurde dieIn-vivo-Aktivität von Clindamycin gegen 50 Oxacillin-sensible (MSSA) und 50 Oxacillin-resistenteStaphylococcus aureus(MRSA-)Stämme mit dem Serumbakterizidie-Test/(SBA) untersucht. Sechs Probanden wurde einmalig 600 mg Clindamycin intravenös infundiert. Weiterhin wurde die minimale Hemmkonzentration (MHK) von Clindamycin gegen 50 Oxacillin-sensible und -resistenteS. aureus und 50 Oxacillin-resistenteStaphylococcus epidermidis-Stämme, von welchen die Hälfte Schleim produzierten, bestimmt. Clindamycin hatte eine gleich hohe Serumbakterizidie gegen Oxacillin-sensible und-resistenteS. aureus-Stämme (durchschnittlicher reziproker SBA Titer von MSSAvs MRSA 1h nach Applikation: 13,0vs 13,45), obwohl die MHK-Werte gegen die Oxacillin-sensiblenS. aureus deutlich geringer waren (MHK 90 von MSSAvs MRSA: 0,06vs 32 mg/l). Die MHK-Werte gegen die Oxacillin-resistentenS. epidermidis-Stämme waren ebenfalls niedrig, ein Unterschied zwischen Schleim-, beziehungsweise nicht schleimproduzierenden Stämmen bestand nicht.

     

Effectiveness and real-world materials compatibility of a novel hydrogen peroxide disinfectant cleaner

A novel 4% hydrogen peroxide disinfectant was effective against methicillin-resistant Staphylococcus aureus (MRSA), Clostridioides difficile spores, carbapenem-resistant Escherichia coli, and 2 strains of Candida auris. In laboratory testing, a sodium hypochlorite disinfectant caused fading and loss of pliability of a hospital mattress, but the hydrogen peroxide disinfectant did not. These findings suggest that the hydrogen peroxide-based disinfectant may be a useful addition to the sporicidal disinfectant products available for use in healthcare settings.     

Is methicillin-resistant Staphylococcus aureus an emerging community pathogen? A review of the literature

OBJECTIVES:

To discuss the historical epidemiology of methicillin-resistant Staphylococcus aureus (MRSA) and review the literature suggesting that MRSA has become a community pathogen.

DATA SOURCES:

A search of the MEDLINE database was performed, encompassing all English or French language citations from 1966 to 1999 and containing the subjects and/or text words: ''Staphylococcus aureus'', ''methicillin resistance'', ''endocarditis'', ''cellulites'', ''pneumonia'' and ''community-acquired''. Articles published in other languages that provided English or French abstracts were included. All relevant references cited in articles obtained from the MEDLINE database and book chapters were also included.

DATA EXTRACTION:

All articles obtained from the above sources were examined and were included in the review if a laboratory or epidemiological study of community-acquired MRSA was presented.

DATA SYNTHESIS AND CONCLUSIONS:

MRSA has emerged over the past 30 years to become a worldwide nosocomial pathogen and has recently been reported as a cause of community-acquired infections. The changing epidemiology of MRSA is likely because of two mechanisms: the movement of nosocomial MRSA strains into the community and the de novo appearance of community strains resulting from the transfer of genetic material from methicillin-resistant Gram-positive organisms to sensitive S aureus strains. The emergence of MRSA as a community pathogen has occurred at a slower rate than it did for penicillin-resistant S aureus (PRSA) in the 1950s and 1960s, possibly because the mechanism of methicillin resistance does not exhibit the same ease of transferability as that of penicillin resistance. Four case reports, seven case series, 10 case-control studies and two cohort studies on community-acquired MRSA were analyzed. Determining whether these reports involve new community-acquired strains rather than previously acquired nosocomial strains can be problematic. It appears, however, that MRSA strains of both nosocomial and community origin are now endemic in certain communities in different parts of the world. Few surveillance studies of nonhospitalized patient populations have been performed to date; thus, the true prevalence of MRSA in the community at large is essentially unknown, although it appears to be low. At present, the empirical treatment of community-acquired S aureus infections with a beta-lactamase-stable beta-lactam antibiotic is appropriate for most populations. However, empirical vancomycin therapy for serious S aureus infections should be strongly considered for patients with significant risk factors for previously-acquired nosocomial MRSA or for patients belonging to outpatient populations with a proven high prevalence of MRSA. Increasing vancomycin use will likely have a significant impact on the development of resistance in Gram-positive organisms.Key Words: Community-acquired disease, Drug resistance, Methicillin-resistant Staphyloccus aureusStaphylococcus aureus has historically been a major human pathogen and continues to be one of the most commonly implicated bacteria causing human disease throughout the world. Before the widespread use of penicillin in the late 1940s and 1950s, staphylococcal septicemia was associated with an extremely high mortality rate (1). Penicillin dramatically improved the prognosis of this infection; however, penicillin-resistant strains were discovered by several investigators shortly after their detection (2-4). Penicillin-resistant S aureus (PRSA) rose to prominence in the hospital setting in the 1950s and 1960s. PRSA strains were discovered in the community shortly after they were found in hospitals, making hospital control of PRSA essentially meaningless within two decades of the strains'' appearance (5). Within the past 20 years, over 90% of North American community and hospital isolates of S aureus have been found to be penicillin resistant (6).The development of beta-lactamase-resistant penicillins such as methicillin and oxacillin in the early 1960s once again revolutionized the treatment of staphylococcal infections. Within a year of their release, however, resistant S aureus strains were reported (7,8) and outbreaks of MRSA infections were described on several continents within several years (9). Over the next 30 years, MRSA emerged as a near ubiquitous nosocomial pathogen. The prevalence of S aureus infections being caused by MRSA as reported by the National Nosocomial Infection Surveillance system in the United States has been steadily increasing, from 2.4% in 1974, 5% in 1981, 29% in 1991 to 43% in 1997 (10-12). Furthermore, the percentage of hospitals treating patients with MRSA infections is also increasing. In a survey of Society for Healthcare Epidemiology of America members in 1990, 97% reported having managed patients with MRSA in their hospitals. While the prevalence of MRSA is increasing, it is increasing at a slower rate than did PRSA in the 1950s and 1960s.It is tempting to predict that MRSA will follow a course similar to that of PRSA, namely that rapid and widespread colonization of people outside of the hospital milieu will result in MRSA becoming the predominant phenotype causing human disease. Such an outcome would obviously have a profound effect on hospital infection control practice and on the empirical use of vancomycin therapy for community-acquired staphylococcal infections. The resulting increased use of vancomycin would in turn have grave implications for the selection of other multidrug-resistant organisms such as vancomycin-resistant enterococci and vancomycin-intermediate S aureus, both of which are selected for by vancomycin use (13,14). Before making such grave predictions, however, it is important to question whether the epidemiology of PRSA and MRSA are truly comparable and examine critically the evidence suggesting that MRSA may be becoming a pathogen in the community.     

Staphylococcus aureus carriage in older populations in community residential care homes: Prevalence and molecular characterization of MRSA isolates

Introduction

The epidemiology of S. aureus depends on conditions in specific populations. Few studies of S. aureus colonization in the older population have been performed in Spain. The aim of this study was to determine the prevalence of methicillin-resistant S. aureus (MRSA) colonization and its molecular epidemiological characteristics in an institutionalized population in community residential care homes in Cadiz, Spain.

Molecular identification and antimicrobial susceptibility of Staphylococcus aureus nasal isolates from medical students in Cartagena,Colombia

Staphylococcus aureus (SA) remains a major cause of nosocomial and community-acquired infections worldwide. Nasal carriage of this bacterium among hospital personnel constitutes an important source for nosocomial infections. A cross-sectional study enrolling the whole medical student population (n = 387) of the School of Medicine at the Universidad de Cartagena, Colombia, was conducted to evaluate the carriage rates of both methicillin sensitive- and methicillin resistant-SA, the frequency of Panton-Valentine leukocidin genes in the isolates, and risk factors associated with carriage in this selected population. After signing an informed consent, participants completed a survey related to possible risk factors for colonization, and nasal swabs were collected from anterior nares. Staphylococcus aureus strains isolated from carriers were subjected to DNA extraction and PCR assays to determine the presence of MecA and Panton-Valentine leukocidin genes. Typing of the staphylococcal chromosomal cassette was performed for methicillin resistant strains. Molecular analysis was performed for only one strain per carrier. Prevalence of carriage for methicillin sensitive- and methicillin resistant-SA was 25% and 1.6% respectively. Most of the methicillin resistant isolates carried the staphylococcal chromosomal cassette type IV and the genes for Panton-Valentine leukocidin. To determine carrier types among medical students, each participant was subjected to four additional swabs, each taken two weeks apart. 9.8% persistent carriers, 53.1% intermittent carriers, and 37.1% non-carriers of SA were found. There was no association between risk factors analyzed and carriage of the bacterium. The study was conducted from April to September 2009 and found a persistent carriage of methicillin resistant-SA strains bearing the genes for Panton-Valentine leukocidin among medical students, evidencing the potential contribution of this portion of healthcare personnel either to the spread or introduction of these strains into the healthcare environment.     

Daptomycin and vancomycin non-susceptible methicillin-resistant Staphylococcus aureus clonal lineages from bloodstream infection in a Brazilian teaching hospital

IntroductionThis study aimed to characterize Staphylococcus aureus isolates from bloodstream infections in patients attending a teaching hospital, between 2011 and 2015.MethodsThe minimum inhibitory concentration for daptomycin, linezolid, oxacillin, teicoplanin, vancomycin, and trimethoprim/sulfamethoxazole was accessed by broth microdilution. SCCmec type and clonal profile were determined by molecular tests. Vancomycin heteroresistance was evaluated using screening tests and by population analysis profile/area under the curve.ResultsAmong 200 S. aureus isolates, 55 (27.5%) were MRSA, carrying SCCmec II (45.5%) or IV (54.5%). The most frequent MRSA lineages were USA100 (ST5-II) (45.5%) and USA800 (ST5-IV) (30.9%). Six isolates were confirmed as vancomycin heteroresistant, showing area under the curve ratio 1.1, 1.2 or 1.3 (four USA100, one USA800 and one USA1100 isolates).ConclusionsDaptomycin and vancomycin non-susceptible MRSA clonal lineages were found in bloodstream infections over five years, highlighting the importance of continuous surveillance of multiresistant bacteria in hospitals.     

Community-acquired methicillin-resistant Staphylococcus aureus from skin and soft tissue infections (in a sample of Egyptian population): analysis of mec gene and staphylococcal cassette chromosome

BackgroundStaphylococcus aureus has been recognized as an important pathogen associated with inpatients and community infections. Community-acquired methicillin-resistant S. aureus (CA-MRSA) infections commonly present as skin and soft-tissue infections (SSTIs). Treatment often includes incision and drainage with or without adjunctive antibiotics.ObjectivesThis study aimed to identify CA-MRSA infections both phenotypically and genotypically, to determine their spectrum of antibiotic resistance, and to establish the best scheme for molecular distinction between hospital-acquired MRSA (HA-MRSA) and CA-MRSA by staphylococcal cassette chromosome mec (SCCmec) typing and detection of Panton Valentine leukocidin (PVL).Materials50 swabs, from skin and soft tissue of infected lesions of outpatients attending the dermatology department of the Medical School, Alexandria University, were collected. Additionally, a nasal swab was taken from every participant.MethodsCollection of swabs from the infected skin and soft tissues, followed by laboratory testing to phenotypically and genotypically identify MRSA. Also, nasal swabs were taken from every patient to identify MRSA colonization.ResultsStaphylococcus aureus strains were identified in 38 (76%) of the 50 clinical isolates. 18 (47.37%) out of the 38 S. aureus strains were resistant to oxacillin and cefoxitin discs, were penicillin binding protein 2a (PBP2a) producers, and were initially diagnosed as MRSA. All of the 18 strains were definitively diagnosed as MRSA by mecA gene detection using real time PCR, while only six (33.33%) strains were PVL positive. Using the sets of primers of Zhang et al.: nine (50%) out of the 18 CA-MRSA strains were SCCmec type V, and one (5.56%) was SCCmec type IVc. Then, using the set of primers by Oliveira et al., two (25%) out of the eight untypable MRSA strains were found to be SCCmec type IV, and six (75%) remained untypable.ConclusionsCA-MRSA must be considered when treating skin and soft tissue infections, especially in developing countries. Empirical use of agents active against CA-MRSA is warranted for patients presenting with serious SSTIs.     

Methicillin/Oxacillin-resistant Staphylococcus aureus as a hospital and public health threat in Brazil

Methicillin-resistant Staphylococcus aureus is an established nosocomial pathogen (HA-MRSA, hospital acquired MRSA), but has recently begun to appear in the community (CA-MRSA, community acquired MRSA). The cause of resistance to methicillin and all other β-lactam antibiotics is the mecA gene, which is situated on a mobile genetic element, the Staphylococcal Cassette Chromosome mec (SCCmec). Seven major variants of SCCmec, type I to VII are distinguished. HA-MRSA disseminated worldwide and causes the majority of S. aureus nosocomial infections with a limited number of clones disseminated including the Brazilian Epidemic Clone (BEC, ST239-MRSA-III). CA-MRSA isolates are susceptible to non-β-lactam antibiotics, usually isolated from healthy individuals which do not possess any unknown risk factors for MRSA infection and are associated with a larger clonal diversity compared with HA-MRSA. However, during recent years distinction between HA-MRSA and CA-MRSA is beginning to fade. Actually, knowledge about MRSA disseminating clones is required to implement any strategies to control the transmission of MRSA either within hospitals or in community. For this reason, rapid identification of strains is an important issue. The rate of HAMRSA can be reduced substantially through the implementation of interventions strategies, even in settings where MRSA is endemic as in most Brazilian hospitals. However, these policies could be quite complicated in the light of an increasing CA-MRSA prevalence in healthcare facilities, considering that distinction between HA-MRSA and CA-MRSA has started to disappear.     

The Increased Risk of Community-Acquired Methicillin-Resistant <Emphasis Type="Italic">Staphylococcus Aureus</Emphasis> in Neck Infections in Young Children

An increase in the isolation rate of methicillin-resistant Staphylooccus aureus (MRSA) in pediatric deep space neck infections including abscesses has been noted in recent years. A recent study by Duggal et al. [9] analyzed the microbiology of deep neck space in children and identify the possible risk factors. Patients younger than 16 months of age were 10 times more likely to have an S. aureus infection as compared to non S. aureus (P < .0001). MRSA comprised the majority of all S. aureus isolates (58%). The majority of community acquired -MRSA (80%) and methicillin sensitive S. aureus isolates (83%) were identified in lateral abscesses in contrast to the non-S. aureus isolates that were located medially (56%). African American pediatric patients accounted for 70% of all deep neck space infections, and 86% of all MRSA infections. Clindamycin resistance was detected in 8% (4/49) of all community-acquired MRSA isolates. The study illustrates significant differences in age and location of neck space infections as they relate to isolation of S. aureus