Methicillin-resistant S. Aureus Carriage Research Articles

High Nasal Carriage of Methicillin-ResistantStaphylococcus aureusAmong Healthy Tanzanian Under-5 Children

This study aimed to determine the prevalence of Staphylococcus aureus and methicillin-resistant S. aureus (MRSA) carriage, risk factors of colonization and antimicrobial susceptibility patterns of S. aureus strains. The study was conducted at the Muhimbili National Hospital in Dar es Salaam, Tanzania. Nasal swabs were obtained from children and S. aureus was isolated and identified using conventional culture methods. MRSA was screened and confirmed using the cefoxitin disk and multiplex real-time polymerase chain reaction, respectively. Antibiotic susceptibility was performed using the Kirby-Bauer disk diffusion method. MRSA isolates were further characterized by pulsed field gel electrophoresis (PFGE) profiling. Of 285 children included in the study, S. aureus was detected in 114 (40%). Of the 114 isolates, 12 (10.5%) were MRSA. PFGE results showed that these MRSA isolates are epidemiologically unrelated. Resistance of all S. aureus to trimethoprim-sulfamethoxazole, tetracycline, gentamicin, and ciprofloxacin was 65.8%, 23.7%, 27.2%, and 4.4%, respectively. No resistance to vancomycin was found. The prevalence of inducible clindamycin resistance, constitutive clindamycin resistance, MS phenotype (resistance to erythromycin alone), and multidrug resistance was 16.7%, 1.8%, 14.0%, and 16.8%, respectively. None of the risk factors examined was found to be significant. This is the first report of S. aureus and nasal carriage of MRSA and a high rate of S. aureus carriage was found in Tanzanian under-5 children. The study findings support the need for proper health education and effective infection control measures for healthcare workers.

Use of Corynebacterium pseudodiphtheriticum for elimination of Staphylococcus aureus from the nasal cavity in volunteers exposed to abnormal microclimate and altered gaseous environment.

Effectiveness of saline suspension of Corynebacterium pseudodiphtheriticum containing spray was assessed in a 30-days chamber experiment modeling the effects of hyperthermia and polluted air on humans. Spray was targeted at eliminating Staphylococcus aureus from the nasal cavity of human subjects. Three of four volunteers became S. aureus carriers in the course of the experiment, and one was a chronic carrier of methicillin-resistant S. aureus (MRSA). Spray application eradicated S. aureus in three subjects and reduced its presence in the MRSA carrier. Results of the study suggest that C. pseudodiphtheriticum can be used for control of S. aureus in the nasal environment. However, further investigations are required.

Recurrent furunculosis: Efficacy of the CMC regimen — skin disinfection (chlorhexidine), local nasal antibiotic (mupirocin), and systemic antibiotic (clindamycin)

The treatment of recurrent furunculosis is poorly documented and represents a public health challenge. The medical care of this disease is often disappointing, especially as the disease evolution is uncertain and relapses occur. We report the efficacy and safety of our CMC regimen: skin disinfection (chlorhexidine), local nasal antibiotic (mupirocin), and systemic antibiotic (clindamycin). Patients attending our institution during the period 2006-2012 for recurrent furunculosis (≥ 4 episodes/y) were enrolled in the study. Clinical and bacteriological data were collected. Staphylococcus aureus colonization was also investigated in close contacts, and carriers were treated. Patients were treated with the CMC regimen: skin disinfection with chlorhexidine for 21 days, nasal mupirocin ointment for 5 days, and oral clindamycin 1800-2400 mg for 21 days. Nineteen patients were included. Their mean age was 36 ± 14.5 y and the male to female sex ratio was 1.1. Screening swabs from all sites were S. aureus-positive in 63% (n = 12), including 4 methicillin-resistant S. aureus (MRSA). Before the CMC regimen, the median time to relapse was 31 days (mean 52 days). The mean number of recurrences was 5.5 ± 2.4/y. After the CMC regimen, among 16 patients who had a complete follow-up, 14 were healed beyond 9 months. Two recurrences occurred, 1 in an MRSA carrier and 1 in a patient with an insufficiently treated dermatosis. No serious side effect occurred that required the cessation of treatment. There are 2 major routes involved in recurrent furunculosis: risk factors and staphylococcal colonization of close contacts. Our procedure is safe and effective, with 87% remission beyond 9 months. It merits testing on larger numbers of participants.

Recurrent Challenges for Clinicians: Emergence of Methicillin-resistant Staphylococcus aureus, Vancomycin Resistance, and Current Treatment Options

Gram-positive pathogens mainly, Staphylococcus aureus, Enterococcus and coagulase-negative Staphylococcus, are developing increasing resistance to glycopeptides that pose a problem in treating infections caused by these pathogens. Vancomycin is the treatment of choice in treating methicillin-resistant S. aureus (MRSA). Community-acquired MRSA is associated with infections in patients without recent history of hospital admission and without the classical risk factors for MRSA carriage (including healthcare personnel). MRSA poses new threats and challenges beyond the hospital with the emergence of community-acquired MRSA. Indiscriminate use of vancomycin leads to the emergence and spread of vancomycin resistance in multidrug resistant strains is of growing concern in the recent years. Minimum Inhibitory concentration (MIC) remains an important determinant in choosing the right antibiotics. Infections caused by MRSA strains with vancomycin MIC > 4 μg/mL leads to the vancomycin treatment failure. The Clinical Laboratory Standards Institute had also lowered the cut-off susceptibility and resistance breakpoints for vancomycin. Despite the availability of newer antimicrobial agents (Linezolid, Daptomycin, Tigecycline) for drug-resistant Gram-positive pathogens, clinicians and patients still need options for treatment of MRSA infection. There is a need to reduce the global burden of infections caused by Gram-positive pathogens and its resistant strains (mainly MRSA). Continuous efforts should be made to prevent the spread and the emergence of glycopeptide resistance by early detection of the resistant strains and using the proper infection control measures in the hospital setting.

Dynamic pattern and genotypic diversity of Staphylococcus aureus nasopharyngeal carriage in healthy pre-school children

It is common wisdom that persistent carriage of Staphylococcus aureus is more frequent in young children than in adults. The objectives of this study were to assess the S. aureus temporal carriage pattern among a healthy community of pre-school children, with concomitant description of genotype diversity, toxin-encoding genes and antibiotic resistance. Among 333 children 3-6 years of age, S. aureus nasopharyngeal carriage was assessed over one school year by culture of three sequential nasopharyngeal aspirates. Identification, methicillin resistance and toxin production profile were determined by PCR. Genotyping was performed by spa sequencing and multilocus sequence typing (MLST). Out of 830 samples collected, 286 (34%) yielded S. aureus from 185 carriers (55%). Based on consecutive genotype analysis, only 40/268 (15%) children could be classified as persistent carriers, and the remaining 118 (44%) showed intermittent carriage. spa typing revealed 82 types clustered into 13 spa clonal complexes (CCs). Fourteen strains isolated from 11 (3%) children were methicillin-resistant S. aureus (MRSA), half of these strains belonged to the commonly hospital-associated spa t008-ST8-SCCmec IV. Methicillin-susceptible S. aureus (MSSA) were genotypically more diverse. Toxic shock syndrome toxin and egc1/2 complexes were highly prevalent (24%). Contrastingly, Panton-Valentine leucocidin (PVL) was carried only by three MSSA strains (0.6% of children). Exfoliative toxins were detected in 10 (3.5%) MSSA strains, of which 5 were related to the impetigo clone CC121. Although S. aureus nasopharyngeal carriage was high among healthy pre-school children, persistent carriage seems to be less frequent than previously reported. The prevalence of MRSA carriage was 3%, but was not associated with PVL.

High Prevalence of Exfoliative Toxins Among Carrier Isolates of Staphylococcus aureus from Healthy Individuals from Various Communities in Chennai, South India

Staphylococcus aureus causes infections both in community and hospital settings, nasal carriage is the important source of these infections. A total of 103 carrier isolates of S. aureus from 352 asymptomatic individuals were screened for methicillin-resistant S. aureus (MRSA) and exfoliative toxins (A, B and D) by two sets of multiplex PCRs. The overall nasal carriage of MRSA was found to be 13/352 (3.7%), of which 4 were found to be positive for Panton valentine leucocidin (PVL). Twelve (11.65%) strains were found to carry exfoliative toxins and belonged to one of the following spa types t159, t209 and t1515. High prevalence of exfoliative toxins, pvl and MRSA pose a major threat to public health, since the isolates were from the healthy in various community settings.

Aumento significativo de la colonización por Staphylococcus aureus entre los estudiantes de medicina durante la realización de las prácticas en el hospital

IntroductionStaphylococcus aureus is a pathogen of major concern. The emergence of methicillin-resistant S. aureus (MRSA) has increasingly complicated the therapeutic approach of hospital-acquired infections. Surveillance of MRSA and control measures must be implemented in different healthcare settings, including screening programs for carriers. Our first aim was to determine the prevalence of methicillin-susceptible S. aureus (MSSA) and MRSA nasal carriage in medical students from the Clínico San Carlos Hospital (Madrid). As the MRSA carrier rate in healthcare workers is higher than in the general population, we hypothesised that carrier rate could be increased during their clinical practice in their last three years. MethodsWe performed an epidemiologic al study of the prevalence of S. aureus colonisation among a group of medical students, who were sampled in 2008 in their third-year, and in 2012 when this class was in its sixth year. ResultsWe have found a significant increase in MSSA carriage, from 27% to 46%. There were no MRSA colonisations in the third-year, but one was found in the sixth-year group. The large majority of strains (89%) of strains were resistant to penicillin, and 27% to erythromycin and clindamycin. As 19 coagulase-negative Staphylococcus MR were also identified, a horizontal transfer of genes, such as mecA gene to S. aureus, could have occurred. ConclusionsMedical students are both, at risk for acquiring, and a potential source of nosocomial pathogens, mainly MSSA. Therefore, they should take special care for hygienic precautions, such as frequent and proper hand washing, while working in the hospital.

Evolution of Multidrug-ResistantStaphylococcus aureusInfections in Horses and Colonized Personnel in an Equine Clinic Between 2005 and 2010

A total of 70 Staphylococcus aureus isolates from postoperative infections in hospitalized horses were isolated between January 2005 and January 2011. Among them, 12 isolates were methicillin-susceptible S. aureus (MSSA), 18 were borderline-oxacillin-resistant S. aureus (BORSA), and 40 were methicillin-resistant S. aureus (MRSA). During the same period, the equine clinic personnel were screened for nasal carriage of BORSA and MRSA. Genotyping revealed that BORSA ST1(MLST)-t2863(spa) isolates were responsible for most equine infections and were the main isolates found in colonized members of the personnel between 2005 and 2007, and that in 2007, MRSA ST398-t011-IVa(SCCmec) emerged in infection sites and personnel, replacing BORSA. Besides decreased susceptibility to oxacillin, all MRSA and BORSA of these two major clonal lineages displayed resistance to gentamicin and kanamycin conferred by the aac(6')-Ie-aph(2')-Ia gene and to trimethoprim conferred by dfr(K) in MRSA and dfr(A) in BORSA. All MRSA had additional resistance to tetracycline conferred by tet(M), whereas BORSA generally also display resistance to streptomycin conferred by str. The number of hospital-acquired MRSA infections in horses could be limited after the introduction of basic hygiene measures and personnel decolonization. Two MRSA carriers could not be decolonized using mupirocin, and a year after decolonization, additional members were recolonized with MRSA. Hygiene measures should, therefore, be maintained to limit the transmission of S. aureus between personnel and horses.

Distribution of Staphylococcus aureus strains colonized in healthy community population and molecular epidemiological characteristics for MRSA strains

To investigate the nasal colonization of Staphylococcus (S.) aureus strains among medical university students in Shenyang and to study the molecular epidemiological characteristics of methicillin resistant S. aureus (MRSA) strains. Sterilized nasal swabs were used to collect nasal bacteria from both nares of the students. Nasal specimens were further identified as S. aureus strains, sensitive or resistant to methicillin through a series of tests. Molecular related methods including staphylococcal cassette chromosome mec (SCCmec) typing, pulsed- field gel electrophoresis (PFGE), coagulase isotyping and minimum inhibitory concentration (MIC) determination etc. were used to characterize the isolates. Prevalence of the panton-valentine leukocidin (pvl) genes (lukS and F-PV) among the isolates was also assessed. Staphylococci were found in 488 specimens from 977 participants through the surveillance program, conducted in 2009. Of the 488 specimens being tested, 364 were identified as coagulase-negative staphylococci (CoNS) and 124 as S. aureus. MRSA strain among the S. aureus isolates was accounted for 3.4%. In the surveillance program conducted in 2010, staphylococci grew in 310 specimens from 657 participants. Of the 310 specimens tested, 195 were identified as CoNS and 115 as S. aureus. The percentage of MRSA strains among the S. aureus isolates was 7.7%. In total, 239 students carried S. aureus, and the percentage of MRSA carriers among the total specimens tested in this study was 5.1%. Most of the MRSA strains could be classified into one of the five types of SCCmec elements. Type IV a SCCmec strains were most frequent seen overall (10 isolates). A total of 11 pulsotype were identified among the MRSA strains and were classified into 7 major groups (A to G) by the mutual correlations of their banding patterns. Ten MRSA strains were identified as pvl positive strains. An MRSA clone (IV a SCCmec pulsotype A) carrying pvl toxin gene was found to be prevalent in the nares of the healthy university students.

Preoperative carriage and postoperative same-species sternal wound infection after cardiac surgery

Sternal wound infection (SWI) after cardiac surgery remains an important problem. Prediction of pathogens involved in such infection could guide antibiotics. From April 1, 2006 to December 31, 2008, retrospectively, we evaluated the diagnostic value of preoperative methicillin-sensible Staphylococcus aureus (MSSA), methicillin-resistant S. aureus (MRSA) or multi-drug resistant Gram-negative bacillus (MDRGNB) carriage to predict same-pathogens involved in postoperative SWI. All patients referred for elective cardiac surgery were screened using multisite (nares, axillae, rectal) sampling at admission to detect MSSA, MRSA, and MDRGNB. Of the 1895 patients addressed, 425 patients (22.4%) were colonized at admission. Preoperative carriers more frequently developed SWI than non-carriers, respectively, 11% vs. 5.5% (P<0.05). Because of the small sample, MDRGNB carriers could not be analyzed. For prediction of MSSA SWI with preoperative MSSA carriage, the area under the receiver operating characteristic (ROC) curve was 0.720 (95% confidence interval (CI), 0.364-0.796) and 0.710 (95% CI, 0.623-0.787) for prediction of MRSA SWI with preoperative MRSA carriage. Preoperative MSSA carriage is frequent but preoperative MRSA or MDRGNB carriage remains infrequent. The ability of preoperative carriage to predict a same-pathogen-postoperative SWI was low and should not be used to guide empirical antibiotherapy.

Nasal carriage and methicillin resistance of Staphylococcus aureus in patients and hospital staff in a tertiary referral center setting

The prevalence of nasal carriage of Staphylococcus aureus and methicillin-resistant S. aureus (MRSA) were studied from June 2006 – 2007 among in-patients and hospital staff in a tertiary referral center setting in Ankara, Turkey. Methicillin resistance was evaluated by Kirby-Bauer disc diffusion method. Of 438 people, 106 (24.2%) were nasal carriers of S. aureus. The prevalence of nasal carriers for S. aureus were not significantly different between the hospital staff, in-patients and out-patients (p>0.05). The overall prevalence of MRSA was 23.6%. The prevalence of MRSA carrier hospital staffs and in-patients was not significantly different (p>0.05). However, the prevalence of MRSA was higher in the medical staffs and in-patients compared to out-patients (p<0.01). The prevalence of nasal carriers is higher in the hospital staff and in-patients compared to out-patients. Therefore, even a tertiary referral hospital can be the source of methicillin resistance as well as transmission of the resistance. Key words: Nasal carrier, methicillin-resistant Staphylococcus aureus in-patients and hospital staff.

Prevalence and characterization of methicillin-resistant Staphylococcus aureus among healthy children in a city of Argentina

Community acquired methicillin-resistant Staphylococcus aureus (CA-MRSA) is a major global problem. Healthy carriers of S. aureus strains have an important role in the dissemination of this bacterium. The aim of this study was to estimate the prevalence of S. aureus and methicillin-resistant S. aureus (MRSA) carriage among healthy children in a city of Buenos Aires province, Argentina, and to determine the potential risk factors for its acquisition. We also described the molecular features of MRSA strains circulating in this population. S. aureus carriage was investigated in all children attending the last year of kindergarten during the 2008 school- year period. Household contacts of MRSA carriers were also screened. Of 316 healthy children, 98 (31.0%) carried S. aureus, including 14 MRSA carriers (4.4%) and 84 methicillin susceptible S. aureus (MSSA) carriers (26.6%). All MRSA isolates carried the SCC mec type IV cassette. Eight of the fourteen isolates were closely related to the clone responsible for most severe community-acquired MRSA infections caused in our country (CAA: PFGE A, SCC mec IV, spa t311, ST5). Two subtypes (A 1 and A 2) were distinguished in this group by PFGE. Both had agr type II and presented the same virulence determinants, except for PVL coding genes and sea that were only harbored by subtype A 1. Our results, based on the analysis of MRSA isolates recovered in the screening of healthy children, provide evidence of a community reservoir of the major CA-MRSA clone described in Argentina.

Changes in the Nasal Colonization with Methicillin-Resistant Staphylococcus aureus in Children: 2004-2009

Background Staphylococcus aureus is an important cause of infection, particularly in persons colonized with this organism. This study compared the annual prevalence and microbiological characteristics of methicillin-resistant S. aureus (MRSA) nasal colonization in Taiwanese children from 2004 through 2009. Risk factors for MRSA were determined for the overall study period.MethodsChildren from birth to ≤14 years of age presenting for health maintenance visits or attending 1 of 57 kindergartens were recruited. Nasal swabs were obtained, and a questionnaire was administered. The prevalence and microbiological characteristics of MRSA colonization were also calculated for two 3-year periods: 2004–2006 and 2007–2009.ResultsCultures of the anterior nares were positive for S. aureus in 824 (25.8%) of the 3,200 children, and MRSA colonization was found in 371 (11.6%) children. The prevalence of S. aureus colonization decreased from 28.1% in 2004–2006 to 23.3% in 2007–2009 (p<0.01), whereas the prevalence of MRSA colonization increased from 8.1% to 15.1% during this period (p<0.0001). Multivariate analysis revealed that the independent risk factors for MRSA carriage were different for male and female children, and also among age groups. Most MRSA isolates belonged to sequence type 59 (ST59) (86.3%); however, a multiresistant MRSA clone with ST338 background emerged in 2007–2009. Ten (62.5%) of the 16 MRSA isolates expressed the genotypic profile ST338/staphylococcal cassette chromosome mec VT/Panton-Valentine leukocidin-positive/staphylococcal enterotoxin B-positive, and differed only in their antimicrobial susceptibility patterns.ConclusionThe prevalence of nasal colonization by MRSA increased among healthy Taiwanese children from 2004–2006 to 2007–2009, despite an overall decrease in the prevalence of nasal colonization by S. aureus. A multiresistant MRSA clone characterized as ST338 was identified from these children.

Methicillin-Resistant Staphylococcus aureus in Diabetic Foot Infections

Diabetic foot ulcers are often complicated by infection. Among pathogens, Staphylococcus aureus predominates. The prevalence of methicillin-resistant S. aureus (MRSA) in infected foot ulcers is 15-30% and there is an alarming trend for increase in many countries. There are also data that recognize new strains of MRSA that are resistant to vancomycin. The risk for MRSA isolation increases in the presence of osteomyelitis, nasal carriage of MRSA, prior use of antibacterials or hospitalization, larger ulcer size and longer duration of the ulcer. The need for amputation and surgical debridement increases in patients infected with MRSA. Infections of mild or moderate severity caused by community-acquired MRSA can be treated with cotrimoxazole (trimethoprim/sulfamethoxazole), doxycycline or clindamycin when susceptibility results are available, while severe community-acquired or hospital-acquired MRSA infections should be managed with glycopeptides, linezolide or daptomycin. Dalbavancin, tigecycline and ceftobiprole are newer promising antimicrobial agents active against MRSA that may also have a role in the treatment of foot infections if more data on their efficacy and safety become available.

Nasal Carriage of Staphylococcus aureus from Healthy Children Attending Day Care Center

Purpose : This study was performed to investigate the prevalence of Staphylococcus aureus (S. aureus) nasal carriage in Korean children attending day care centers. Methods : During September and October 2009, a survey for nasal carriage of S. aureus and methicillin-resistant S. aureus (MRSA) was conducted among children attending day care centers located in Seoul with questionnaire survey for evaluation of risk factors of acquisition of MRSA was obtained from their guardians. A culture of the anterior nares swabs using enrichment broth was executed for isolating S. aureus and oxacillin susceptibility was assessed by the disk diffusion method. Results : Out of the 428 children enrolled whose mean age was 55 months old, 163 (38.1%) were colonized with S. aureus. Of the 163 isolates, 40 (24.5%) were MRSA. The nasal carriage rate of S. aureus showed an increasing trend with increase of age. Based on the answer to the questionnaire, 9.2% and 3.6% of children had a recent history of hospitalization and surgery, respectively, and approximately 40% of children had a history of prescription of antibiotics within 1 year prior to enrollment. Of the 428 subjects, 40 (9.3%) were MRSA nasal carriers. Conclusion : S. aureus and MRSA carriage rate of children attending day care center in Korea was 38.1% and 9.3%, respectively. Continued surveillance for nasal carriage rate of S. aureus and MRSA (especially community-associated MRSA) is mandatory.

MRSA, screening and implications for the anaesthetist

MRSA, screening and implications for the anaesthetist

Methicillin-resistant Staphylococcus aureus: a new zoonotic agent?

Staphylococcus aureus is a major cause of infection in hospitals and the community. One third of the general population is colonized by the bacterium, constituting a risk factor for acquisition of infection with this pathogen. Worldwide, the increasing antibiotic resistance of S. aureus complicates treatment of infection and control measures. Soon after the introduction of methicillin, the first isolates resistant to this antibiotic were reported and named methicillin-resistant S. aureus (MRSA). During the past decade a major change in MRSA epidemiology has been observed: whereas in the past MRSA was almost exclusively regarded a hospital pathogen, the advent of community-acquired MRSA has led to infections in people without hospital-related risk factors. Recent evidence has also identified a link between colonization of livestock and MRSA carriage and infections in people who work with animals. Screening of pigs and pig farmers in the Netherlands revealed high prevalence of MRSA sequence type (ST) 398 and it has become clear that the emergence of ST398 is not just a Dutch problem, as reports on livestock colonization and human infections are appearing worldwide. In Austria, the ST398 lineage has been detected in dust samples from pig breeding facilities and in food samples. Since the first Austrian detection of this emerging lineage in 2006, 21 human isolates, partially associated with infections, have been observed. MRSA has to be regarded as a new emerging zoonotic agent and livestock may constitute a growing reservoir of the ST398 lineage. More information is needed so that control measures to reduce the impact of the emerging MRSA ST398 lineage on public health can be developed and implemented.

High rates of community-acquired, Panton-Valentine leukocidin (PVL)- positive methicillin-resistant S. aureus (MRSA) infections in adult outpatients in Greece

Staphylococcus aureus was isolated in 88 (30.8%) of 286 adult patients suffering from various skin and soft-tissue infections examined in the outpatient department of a 650 bed tertiary-care hospital of Athens, Greece between January 2006 and December 2007. Twenty-seven (30.7%) of the S. aureus infections were caused by methicillin-resistant S. aureus (MRSA). All MRSA isolates were also resistant to tetracycline, fucidic acid and kanamycin, but were sensitive to gentamicin and tobramycin, as well as to to cotrimoxazole, chloramphenicol, quinolones, clindamycin and erythromycin. All isolates belonged to staphylococcal cassette chromosome mec elements (SCCmec) type IV, and were found to carry the lukF-PV and lukS genes coding for Panton-Valentine leukocidin (PVL). Pulsed-field gel electrophoresis (PFGE) and spa-typing revealed high genetic similarity among all MRSA isolates and with the PFGE pattern of the well-described ST80 clone that seems to be spreading through Europe. The high prevalence of MRSA among S. aureus infections in the community signify that empiric therapy in Greece, when clinically indicated, should exclude beta-lactam antibiotics. Moreover, the establishment of an active screening for PVL-positive community-acquired (CA)-MRSA carriage and the adoption of a search and destroy strategy for CA-MRSA in all patients admitted with purulent skin and soft-tissue is of high priority in Greece as well as in all European countries which face high rates of CA-MRSA infection.

Decontamination strategies for MRSA-colonized patients

Introduction: The fi rst step in the pathogenesis of most skin and soft tissue infections is the colonization of the host by a potential pathogen or pathogens. Staphylococcus aureus has long been an important pathogen, but the dissemination of community-associated methicillin-resistant S. aureus (MRSA) over the past decade, superimposed on the gradually increasing carriage rates of hospital-associated MRSA, have made beta-lactam–resistant S. aureus isolates the dominant etiology of skin and soft tissue infections in many locations across the United States [ 1 ]. The costs of established MRSA infection with regard to prolonged hospital stay, increased mortality, and increased expense have been widely reported [ 2 ], and it is only natural that growing attention has been focused on preventing MRSA infection. Although the anterior nares are the most commonly reported site of MRSA carriage, MRSA may persist in additional sites (eg, skin, chronic wounds, and perianal/rectal carriage) in some individuals or may reside exclusively in sites other than the nares in others. The dynamic aspects of S. aureus carriage are complex: most individuals are transiently colonized for varying intervals, some are persistently colonized at one or more sites when studied longitudinally and a modest fraction of individuals remain persistently culture negative for S. aureus colonization. Several interventional studies have explored the eradication of MRSA carriage. Eradication strategies have tended to use topical agents directed at nares and/or skin decontamination or systemic antibiotics. In general, these studies have been limited by enrollment size, duration of monitoring, and inherent study limitations regarding the distinction in culture-positive patients between decontamination failures and effective eradication followed by acquisition of a distinct MRSA strain.

Peritonitis and Exit-Site Infection in Pediatric Automated Peritoneal Dialysis

We reviewed 30 patients in an automated peritoneal dialysis (APD) program from 2002 to 2006 for peritonitis. Patients were 11.6 +/- 5.5 years old at initiation of peritoneal dialysis (PD) and had a total of 976 PD months. The overall peritonitis rate was 1 episode in 54.2 patient-months, for a rate of 0.22 episode annually. The rate was considered low, which other than being an APD program, may be attributed to adherence to guidelines and in-charge nurse policy. A total of 17 episodes of peritonitis were identified in 9 patients, and the distribution of patient-specific peritonitis incidence appeared bimodal: 87% patients had no or only 1 episode of peritonitis, and 4 patients accounted for 12 episodes, with an average peritonitis rate of 1.0 annually. Causative organisms included Staphylococcus aureus, coagulase-negative Staphylococcus, methicillin-resistant S. aureus (MRSA), Pseudomonas aeruginosa, enterococci, alpha-hemolytic Streptococcus. Five episodes had concurrent exit-site infection with the same organism. During the same period in these 30 patients, 40 episodes of exit-site infection (ESI) were recorded in 23 patients. The overall ESI rate was 1 episode in 24.4 PD months. S. aureus and Pseudomonas aeruginosa were the two most common pathogens, accounting for 70% of the infections. Nasal carriage of MRSA was found in 4 patients, and MRSA ESIs in 2. The ESI rate was not low as that observed in peritonitis, which may be attributed to the humid climate.