Nasal Carriage of Multi-Drug Resistant Panton-Valentine Leucocidin-Positive Methicillin-Resistant Staphylococcus aureus in Children in Tripoli-Libya

Methicillin-resistant Staphylococcus aureus (MRSA) colonized children are at an increased risk of developing infections than methicillin-sensitive S. aureus colonized children. Nasal specimens from inpatient children, mothers of inpatient children, healthcare workers, and outpatient children at Tripoli Children Hospital (TCH) were examined for MRSA by chromogenic MRSA ID medium. Susceptibility of MRSA isolates to antibiotics was determined by the disc diffusion method. The nasal carriage rate of MRSA among inpatient children (8.3%, 24 of 289), their mothers (11%, 22 of 200), and healthcare workers (12.4%, 22 of 178) was significantly higher than among outpatient children (2.2%, 2 of 91) (P < 0.05, P < 0.02, and P < 0.006, respectively). Of the examined MRSA isolates (N = 35) 10 (28.6%) were positive for Panton-Valentine leucocidin genes by polymerase chain reaction. Multidrug resistance was found in 24.3% (17 of 70) of MRSA isolates. Nasal carriage of multidrug-resistant Panton-Valentine leucocidin-positive MRSA is not uncommon among inpatient children and their mothers in Tripoli.     

Risk Factors of Methicillin-Resistant Staphylococcus aureus Infection and Correlation With Nasal Colonization Based on Molecular Genotyping in Medical Intensive Care Units: A Prospective Observational Study

Methicillin-resistant Staphylococcus aureus (MRSA) is a common and important cause of colonization and infection in medical intensive care units (ICU). The aim of this study was to assess association factors between MRSA nasal colonization and subsequent infections in medical ICU patients by clinical investigation and molecular genotyping.A prospective cohort observational analysis of consecutive patients admitted to medical ICUs between November 2008 and May 2010 at a tertiary teaching hospital were included. To detect MRSA colonization, the specimens from the nares were obtained within 3 days of admission to the ICU and again 1 week following admission to the ICU. Genetic relatedness for colonized and clinical isolates from each study patient with MRSA infection were analyzed and compared.A total of 1266 patients were enrolled after excluding 195 patients with already present MRSA infections. Subsequent MRSA infection rates were higher in patients with nasal colonization than in those without (39.1% versus 14.7%, respectively). Multivariate Poisson regression analysis demonstrated that nasal MRSA colonization (relative risk [RR]: 2.50; 95% confidence interval [CI]: 1.90–3.27; P < 0.001) was independent predictors for subsequent MRSA infections. History of tracheostomy, however, was a protective predictor in all patients (RR: 0.38; 95% CI: 0.18–0.79; P = 0.010) and in patients with MRSA nasal colonization (RR: 0.22; 95% CI: 0.55–0.91; P = 0.037). Molecular genetics studies revealed that most MRSA isolates were healthcare-associated clones and that nasal and clinical isolates exhibited up to 75% shared identity.Methicillin-resistant S. aureus nasal colonization was significantly associated with subsequent MRSA infection among medical ICU patients. Previous MRSA infection was associated with subsequent MRSA infections, and history of tracheostomy associated with reducing this risk. Most MRSA isolates were healthcare-associated strains that were significantly correlated between nasal and clinical isolates.     

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.     

Community-based cluster of methicillin-resistant Staphylococcus aureus in Manitoba

A community-based, single strain cluster of methicillin-resistant Staphylococcus aureus (MRSA) is described. The cluster of cases was identified in a small rural community in southwestern Manitoba, although some spread of the MRSA strain to neighbouring communities was observed. The majority of people were otherwise healthy, had no contact with the hospital system and did not fit the profile of those at risk for MRSA infection.Key Words: Community cluster, Methicillin-resistant Staphylococcus aureus, MRSAMethicillin-resistant Staphylococcus aureus (MRSA) is recognized worldwide as a major nosocomial pathogen in hospitals. Guidelines have been established to provide a framework for the management of patients with MRSA in health care facilities. However, the epidemiology and control of MRSA in the community is not clear. We recently investigated a single strain community outbreak of MRSA in a small rural community. This report describes the community spread of this strain among otherwise healthy individuals with no clear predisposing risk factors.     

Fifteen-year study of the changing epidemiology of methicillin-resistant Staphylococcus aureus

Purpose

The study’s purpose was to elucidate the evolutionary, microbiologic, and clinical characteristics of methicillin-resistant Staphylococcus aureus (MRSA) infections.

Methods

MRSA cases from military medical facilities in San Diego, from 1990 to 2004, were evaluated and categorized as community-acquired or nosocomial. Sequence type, staphylococcal chromosomal cassette gene type, and Panton-Valentine leukocidin gene status were determined for a subset of isolates.

Results

Over the 15-year period, 1888 cases of MRSA were identified; 65% were community acquired. The incidence (155 infections/100 000 person-year in 2004) and household-associated cases rapidly increased since 2002. Among persons with community-acquired MRSA, 16% were hospitalized and only 17% were initially given an effective antibiotic. Community-acquired MRSA cases compared with nosocomial MRSA cases were more often soft-tissue and less often urinary, lung, or bloodstream infections (P < .001). Patients with community-acquired MRSA were younger (22 vs 64 years, P < .001) and less likely to have concurrent medical conditions (9% vs 98%, P < .001). Clindamycin resistance increased among community-acquired MRSA isolates during 2003 and 2004 compared with previous years (79% vs 13%, P < .001). Genetically, nosocomial MRSA isolates were significantly different than those acquired in the community. Although community-acquired MRSA isolates were initially diverse by 2004, one strain (staphylococcal chromosomal cassette type IV, sequence type 8, Panton-Valentine leukocidin gene positive) became the predominant isolate.

Conclusions

Community-acquired and intrafamilial MRSA infections have increased rapidly since 2002. Our 15 years of surveillance revealed the emergence of distinct community-acquired MRSA strains that were genetically unrelated to nosocomial MRSA isolates from the same community.     

Caracterización molecular de cepas de Staphylococcus aureus resistentes a meticilina ST398 en pacientes con infecciones cutáneas y sus familiares

Introduction

Livestock-associated methicillin-resistant Staphylococcus aureus (LA-MRSA) of sequence type ST398 is a genetic lineage also described in human infections.

Methods

Cutaneous infections related with MRSA ST398 are described in 3 patients, two of them pig farmers. The MRSA nasal carriage by patients and their relatives was also studied. MRSA ST398 strains were typed (SCCmec, spa, agr and MLST) and the antimicrobial resistance pattern and virulence genes were determined.

Results

Twenty MRSA ST398 isolates were recovered in lesions of three patients, and in nasal samples of two patients and five relatives. Isolates were typed: spa-type t011 or t108; agr-type I and SCCmec IVa or V. MRSA strains were tetracycline-resistant and 15 of them showed a phenotype and genotype of multi-resistance, but they were free of tested virulence genes.

Conclusions

LA-MRSA ST398 is an emergent problem in our country, mainly associated with skin and soft tissue infections in people with professional relationships with pig farms. Tetracycline resistance is an important marker for MRSA ST398 detection.     

A case of acute cholecystitis caused by methicillin-resistant Staphylococcus aureus in an immunocompromised patient

Although infections with Staphylococcus aureus can implicate multiple organ systems, involvement of the biliary tract is rare. A case of acute cholecystitis and bacteremia with methicillin-resistant S aureus (MRSA) in a patient with HIV infection is presented. The MRSA isolate was found to be a community-associated strain. The present case highlights the invasive nature of staphylococcal infections and the emerging importance of community-associated MRSA strains.     

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.     

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.     

Frequency of MRSA in diabetic foot infections

Staphylococcus aureus is one of the most common bacterial pathogens isolated from diabetic foot infections (DFIs). The increasing prevalence of meticillin-resistant S. aureus (MRSA) in patients with diabetes is associated with complications. The aim of this study was to determine the prevalence of S. aureus in DFIs and antibiotic susceptibility patterns of MRSA and non-MRSA isolates. Identification of S. aureus and MRSA was performed by the phenotypic and molecular methods. The Kirby-Bauer and agar dilution methods were performed for determination of antibiotic susceptibility patterns. Thirty-four isolates of S. aureus were isolated from March 2014 to February 2015. The rate of MRSA was 38.23 % according to the disk cefoxitin and oxacillin agar dilution methods, and as by PCR method 12) 35.29 %), isolates were found to have the mecA gene. All MRSA and non-MRSA isolates were susceptible to linezolid and vancomycin. The resistance rate to ceftriaxone was high followed by amoxicillin-clavulanic acid, tetracycline, gentamicin, and erythromycin. The most common bacterial pathogen isolated from DFIs was S. aureus. To ensure effective treatment, accurate detection of MRSA is critical. Our findings showed that MRSA isolates had high-level resistance to antimicrobial agents and that appropriate antibiotic therapy, based on the antibiotic susceptibility pattern, is essential to ensure a good result.     

Interplay of personal,pet, and environmental colonization in households affected by community-associated methicillin-resistant Staphylococcus aureus

Objective

We sought to determine the prevalence, molecular epidemiology, and factors associated with Staphylococcus aureus environmental surface and pet colonization in households of children with community-associated methicillin-resistant S. aureus (CA–MRSA) infection.

Molecular Epidemiological Analysis of Methicillin-Resistant Staphylococcus aureus Isolates From a Medical Intensive Care Unit: A Comparison of Nasal and Clinical Isolates

BackgroundThe control of nosocomial transmission of methicillin-resistant Staphylococcus aureus (MRSA) represents a significant challenge to infection control professionals. Nasal carriage colonization by MRSA plays a crucial role in the epidemiology and pathogenesis of this infection.MethodsPatients in the medical intensive care unit (ICU) between November 2010 and March 2011 were swabbed when hospitalized, reswabbed 1 week later and for a third time, when they were discharged from the ICU. All swabs were examined within 2 hours of collection using ChromID MRSA-Select agar plates to detect MRSA. Positive specimens were determined to have the mecA and femB gene through amplification with duplex polymerase chain reaction. Repetitive element sequence–based polymerase chain reaction was used to investigate the epidemiological types of MRSA isolates in the third screening and clinical isolates obtained from 2007 to 2010 in West China Hospital. A comparison of molecular types was performed to investigate the genetic relationship between nasal and clinical isolates.ResultsAfter the third screening, 16 nasal MRSA isolates were identified. Epidemiological analysis revealed that 16 nasal MRSA isolates and 37 clinical MRSA isolates differentiated into 2 clusters, comprising 9 subclusters. Of the 16 nasal strains, 11 (68.8%) belonged to subcluster I of cluster I; 3 of 9 subclusters consisted of both nasal and clinical isolates, while 4 of 9 subclusters consisted of clinical isolates and only 2 of 9 consisted of nasal isolates.ConclusionsOur study indicated a high degree of genetic relatedness between nasal and clinical MRSA isolates. The molecular typing of MRSA is critical for controlling the nosocomial transmission of this pathogen in ICU setting and defining a nosocomial infection control policy.     

Misidentification of meticillin-resistant Staphylococcus aureus by the Cepheid Xpert MRSA NxG assay,the Netherlands,February to March 2021

We describe two false-negative results in the detection of meticillin-resistant Staphylococcus aureus (MRSA) of sequence type 398 and spa type t011 using the Cepheid Xpert MRSA NxG assay. The isolates were recovered in late February and early March 2021 from two patients in different hospitals in the northern Netherlands. Variations between the two isolate genomes indicate that this MRSA strain might have been spreading for some time and could have disseminated to other regions of the Netherlands and other European countries.     

Usefulness of previous methicillin-resistant Staphylococcus aureus screening results in guiding empirical therapy for S aureus bacteremia

BACKGROUND:

Staphylococcus aureus bacteremia (SAB) is an important infection. Methicillin-resistant S aureus (MRSA) screening is performed on hospitalized patients for infection control purposes.

OBJECTIVE:

To assess the usefulness of past MRSA screening for guiding empirical antibiotic therapy for SAB.

METHODS:

A retrospective cohort study examined consecutive patients with confirmed SAB and previous MRSA screening swab from six academic and community hospitals between 2007 and 2010. Diagnostic test properties were calculated for MRSA screening swab for predicting methicillin resistance of SAB.

RESULTS:

A total of 799 patients underwent MRSA screening swabs before SAB. Of the 799 patients, 95 (12%) had a positive and 704 (88%) had a negative previous MRSA screening swab. There were 150 (19%) patients with MRSA bacteremia. Overall, previous MRSA screening swabs had a positive likelihood ratio of 33 (95% CI 18 to 60) and a negative likelihood ratio of 0.45 (95% CI 0.37 to 0.54). Diagnostic accuracy differed depending on mode of acquisition (ie, community-acquired, nosocomial or health care-associated infection) (P<0.0001) and hospital (P=0.0002). At best, for health care-associated infection, prior MRSA screening swab had a positive likelihood ratio of 16 (95% CI 9 to 28) and a negative likelihood ratio of 0.27 (95% CI 0.17 to 0.41).

CONCLUSIONS:

A negative prior MRSA screening swab cannot reliably rule out MRSA bacteremia and should not be used to guide empirical antibiotic therapy for SAB. A positive prior MRSA screening swab greatly increases likelihood of MRSA, necessitating MRSA coverage in empirical antibiotic therapy for SAB.     

Methicillin-resistant Staphylococcus aureus colonization among health care workers in a downtown emergency department in Toronto,Ontario

BACKGROUND:

Methicillin-resistant Staphylococcus aureus (MRSA) acquired in the community, otherwise known as community-acquired MRSA, has emerged rapidly in recent years. Colonization with MRSA has been associated with an increased risk of symptomatic and serious infections and, in some settings, health care workers (HCWs) exhibit a higher prevalence of MRSA colonization.

OBJECTIVE:

To determine MRSA colonization in emergency department (ED) HCWs in the setting of a moderate prevalence of MRSA in skin and soft tissue infections.

METHODS:

The present study was conducted at a downtown ED in Toronto, Ontario. ED HCWs completed a brief questionnaire and swabs were taken from one anterior nare, one axilla and any open wounds (if present). Swabs were processed using standard laboratory techniques.

RESULTS:

None of the 89 staff (registered nurses [n=55], physicians [n=15], other [n=19]) were MRSA positive and 25 (28.1%) were colonized with methicillin-susceptible S aureus.

CONCLUSIONS:

Contrary to common belief among HCWs and previous studies documenting MRSA colonization of HCWs, MRSA colonization of this particular Canadian ED HCW cohort was very low and similar to that of the local population.     

Effizientes MRSA-Management

There are 132,000?cases of colonization or infection caused by methicillin-resistant Staphylococcus aureus (MRSA) documented annually in German hospitals. Therefore, MRSA is one of the most frequent multiresistant microorganisms isolated from patients with healthcare-associated infections. Recently, the European Center for Disease Prevention and Control (ECDC) estimated that MRSA causes an attributable financial burden of 380?million?EUR for the EU healthcare systems. Consequently, the prevention of MRSA is a major goal. Although there is increasing evidence supporting the effectiveness of some preventive interventions (screening, isolation, eradication) with respect to their ability to reduce MRSA, there is an on-going discussion about the cost effectiveness of these measures. In this article, financial aspects associated with MRSA are described and an overview of the current knowledge about the cost effectiveness of several key measures proposed for MRSA prevention is provided.     

Evaluation of MRSASelect? chromogenic medium for the early detection of methicillin-resistant Staphylococcus aureus from blood cultures

INTRODUCTION:

Staphylococcus aureus bacteremia is associated with considerable morbidity and mortality. In theory, reducing the turnaround time in reporting of methicillin-resistant S aureus (MRSA) among patients with bactermia could assist with the rapid optimization of antimicrobial therapy.

OBJECTIVE:

To evaluate the sensitivity and specificity of MRSASelect (Bio-Rad Laboratories, USA), a chromogenic medium, in the early detection of MRSA from blood cultures growing Gram-positive cocci in clusters, and to confirm that routine use of this medium would, in fact, reduce turnaround time for MRSA identification.

METHODS:

The present study was conducted at three microbiology laboratories in Manitoba. Between April 2010 and May 2011, positive blood cultures with Gram-positive cocci in clusters visualized on Gram stain were subcultured to both MRSASelect and routine media. MRSA isolates were identified using conventional microbiological methods from routine media and using growth with the typical colony morphology (pink colony) on MRSASelect medium.

RESULTS:

A total of 490 blood cultures demonstrating Gram-positive cocci in clusters on Gram stain were evaluated. S aureus was recovered from 274 blood cultures, with 51 S aureus isolates (51 of 274 [18.6%]) identified as MRSA. MRSASelect medium had a sensitivity of 98%, a specificity of 100%, a positive predictive value of 100% and a negative predictive value of 99.8% for the recovery and identification of MRSA directly from positive blood culture bottles. In addition, use of MRSASelect medium was found to improve turnaround time in the detection of MRSA by almost 24 h relative to conventional methods.

DISCUSSION:

These data support the utility of MRSASelect medium for the rapid identification of MRSA from positive blood cultures. Further clinical studies are warranted to determine whether the improvement in turnaround time will result in a measurable reduction in suboptimal antimicrobial therapy and/or improvement in patient outcome.     

Nosokomiale Infektionen

Inadequate antibiotic prescribing and poor adherence to infection control guidelines are the main reasons for the development and spread of methicillin-resistant Staphylococcus aureus (MRSA) and Clostridium difficile (CD), the most important cause of antibiotic-associated diarrhoea (AD) and colitis. Both CDAD and MRSA infection are associated with significant morbidity, excess mortality and substantial consumption of resources. Increases in the incidence of both infections have been observed in Germany and represent a challenge to clinicians, infection control practitioners, quality management teams und hospital administration. Prudent use of antibiotics, in particular critical prescribing of fluoroquinolones and cephalosporins, is an important component in programmes aiming at an effective prevention of MRSA and CDAD. Other similarly important components are minimization of pathogen transmission between patients and healthcare personnel by isolation and contact precautions, early detection of MRSA carriers and MRSA decolonization treatment. It must be ascertained that patients nursed in isolation rooms receive medical care of similar high quality as all other patients. Over the last years, there has been no major breakthrough in therapy and outcomes in both CDAD and MRSA infection. Close collaboration between hospitals, nursing homes and primary care institutions will be critical for better control of MRSA and CDAD.     

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.