Community-acquired and clindamycin-susceptible methicillin-resistant Staphylococcus aureus in children

Antimicrobial Treatment of Staphylococcus aureus Biofilms

Staphylococcus aureus is a microorganism frequently associated with implant-related infections, owing to its ability to produce biofilms. These infections are difficult to treat because antimicrobials must cross the biofilm to effectively inhibit bacterial growth. Although some antibiotics can penetrate the biofilm and reduce the bacterial load, it is important to understand that the results of routine sensitivity tests are not always valid for interpreting the activity of different drugs. In this review, a broad discussion on the genes involved in biofilm formation, quorum sensing, and antimicrobial activity in monotherapy and combination therapy is presented that should benefit researchers engaged in optimizing the treatment of infections associated with S. aureus biofilms.

Osteomyelitis in Children from Rural Population of Uttar Pradesh

Occurrence of Staphylococcus aureus in children with osteomyelitis. This study was conducted at K. M. M. C. & Hospital, Mathura (UP). A total of 60 patients with osteomyelitis contributed to this study from October 2017 to October 2019. Patients with known immunodeficiency syndromes were excluded. Specimen collections were meticulously performed to avoid contamination which was accomplished by needle aspiration or surgical sampling. Staphylococcus aureus was recovered in more than half of the cases of osteomyelitis in both infants and children. Amikacin, Clindamycin and Cefazolin were effective in such cases. The distal end of the femur and upper-end tibia were the most common sites of infection where boys were more infected than girls. The haematogenous route was the main cause of the transmission of osteomyelitis in children. Principally Staphylococcus aureus causes the majority of cases of osteomyelitis in children followed by H. influenza, Group B Streptococcus, P. aeruginosa, E. coli and Serratia marcescens.

Methicillin-resistant Staphylococcus aureus: an overview of basic and clinical research

Methicillin-resistant Staphylococcus aureus (MRSA) is one of the most successful modern pathogens. The same organism that lives as a commensal and is transmitted in both health-care and community settings is also a leading cause of bacteraemia, endocarditis, skin and soft tissue infections, bone and joint infections and hospital-acquired infections. Genetically diverse, the epidemiology of MRSA is primarily characterized by the serial emergence of epidemic strains. Although its incidence has recently declined in some regions, MRSA still poses a formidable clinical threat, with persistently high morbidity and mortality. Successful treatment remains challenging and requires the evaluation of both novel antimicrobials and adjunctive aspects of care, such as infectious disease consultation, echocardiography and source control. In this Review, we provide an overview of basic and clinical MRSA research and summarize the expansive body of literature on the epidemiology, transmission, genetic diversity, evolution, surveillance and treatment of MRSA.

Community-Associated Methicillin-Resistant Staphylococcus aureus: New Bug, Old Drugs

Objective:

To discuss community-associated methicillin-resistant Staphylococcus aureus (CA-MRSA) infections and evaluate older antibiotics as suitable therapeutic treatment options.

Data Sources:

Searches of MEDLINE, EMBASE, and the Cochrane Library (1966–May 2006) were performed using the key terms methicillin resistance, community-acquired, community associated, treatment, Staphylococcus aureus, mec, and Panton-Valentine leukocidin.

Study Selection and Data Extraction:

All articles were critically evaluated and all relevant information was included in this review.

Data Synthesis:

There has been a documented shift of methicillin resistance occurring in staphylococcal infections manifested within the community. Infections caused by CA-MRSA possess unique characteristics including lack of hospital-associated risk factors, improved susceptibility patterns, distinct genotypes, faster doubling times, and additional toxins. Potential therapeutic options to treat these infections include trimethoprim/sulfamethoxazole (TMP/SMX), clindamycin, tetracyclines, fluoroquinolones, and new antimicrobials.

Conclusions:

CA-MRSA infections can be successfully treated with older, oral antibiotic agents including TMP/SMX, clindamycin, and tetracyclines. Fluoroquinolones and linezolid should be avoided as first-line agents.

Staphylococcus aureus infections: epidemiology, pathophysiology, clinical manifestations, and management

Staphylococcus aureus is a major human pathogen that causes a wide range of clinical infections. It is a leading cause of bacteremia and infective endocarditis as well as osteoarticular, skin and soft tissue, pleuropulmonary, and device-related infections. This review comprehensively covers the epidemiology, pathophysiology, clinical manifestations, and management of each of these clinical entities. The past 2 decades have witnessed two clear shifts in the epidemiology of S. aureus infections: first, a growing number of health care-associated infections, particularly seen in infective endocarditis and prosthetic device infections, and second, an epidemic of community-associated skin and soft tissue infections driven by strains with certain virulence factors and resistance to β-lactam antibiotics. In reviewing the literature to support management strategies for these clinical manifestations, we also highlight the paucity of high-quality evidence for many key clinical questions.

Skin and soft tissue infections

The approach to common skin and soft tissue infections (SSTIs) was previously well understood. However, the recent emergence of community-associated methicillin resistant Staphyloccocus aureus as a common pathogen has changed the epidemiology of these infections and has led clinicians to alter their practice and treatment of SSTI. This article discusses the present epidemiology of SSTI and community-acquired methicillin-resistant Staphylococcus aureus, evidence-based approach to incision and drainage, the utility of adjuvant antibiotic therapy after abscess drainage, and current antimicrobial approach to cellulitis and nondrained SSTIs. Methods to reduce transmission and recurrence of SSTI through decolonization strategies are also discussed.

Community-acquired disseminated methicillin-resistantStaphylococcus aureusinfection: case report and clinical implications

A 6-year-old girl with community-acquired disseminated infection caused by methicillin-resistant Staphylococcus aureus (MRSA) is described. She had sepsis, meningo-encephalitis, pyomyositis, osteomyelitis, pericarditis and pulmonary embolisation caused by a multi-resistant strain of MRSA. Vancomycin is not routinely recommended as the first-line antimicrobial agent for suspected Staphylococcus aureus infection; however, it should be considered pending susceptibility results in patients presenting with severe sepsis in areas where the prevalence of MRSA is high.

Emergency ultrasound-assisted examination of skin and soft tissue infections in the pediatric emergency department

OBJECTIVES

The objective was to evaluate the test characteristics of clinical examination (CE) with the addition of bedside emergency ultrasound (CE+EUS) compared to CE alone in determining skin and soft tissue infections (SSTIs) that require drainage in pediatric patients.

METHODS

This was a prospective study of CE+EUS as a diagnostic test for the evaluation of patients 2 months to 19 years of age evaluated for SSTIs in a pediatric emergency department (ED). Two physicians clinically and independently evaluated each lesion, and the reliability of the CE for diagnosing lesions requiring drainage was calculated. Trained pediatric emergency physicians performed US following their CEs. The authors determined and compared the test characteristics for evaluating a SSTI requiring drainage for CE alone and for CE+EUS for those lesions in which the two physicians agreed and were certain regarding their CE diagnosis (clinically evident). The performance of CE+EUS was evaluated in those lesions in which the two physicians either disagreed or were uncertain of their diagnosis (not clinically evident). The reference standard for determining if a lesion required drainage was defined as pus expressed at the time of the ED visit or within 2 days by follow-up assessment.

RESULTS

A total of 387 lesions underwent CE+EUS and were analyzed. CE agreement between physicians was fair (κ = 0.38). For the 228 lesions for which physicians agreed and were certain of their diagnoses, sensitivity was 94.7% for CE and 93.1% for CE+EUS (difference = -1.7%; 95% confidence interval [CI] = -3.4% to 0%). The specificity of CE was 84.2% compared to 81.4% for CE+EUS (difference = -2.8%; 95% CI = -9.7% to 4.1%). For lesions not clinically evident based on CE, the sensitivity of CE was 43.7%, compared with 77.6% for CE+EUS (difference = 33.9%; 95% CI = 1.2% to 66.6%). The specificity of CE for this group was 42.0%, compared with 61.3% for CE+EUS (difference = 19.3%; 95% CI = -13.8% to 52.4%).

CONCLUSIONS

For clinically evident lesions, the addition of ultrasound (US) did not significantly improve the already highly accurate CE for diagnosing lesions requiring drainage in this study population. However, there were many lesions that were not clinically evident, and in these cases, US may improve the accuracy of the CE.

Skin and soft tissue infections due to Panton-Valentine leukocidin producing Staphylococcus aureus

OBJECTIVE

The authors had for aim to describe the epidemiological and clinical characteristics, and the treatment of patients presenting with skin and soft tissue infections due to Panton-Valentine leukocidin (PVL) producing Staphylococcus aureus in the Nord-Pas-de-Calais (NPDC) region, North of France.

METHODS

We included patients presenting with PVL producing S. aureus infection from seven hospitals in the NPDC region, between February 2004 and April 2008. We retrospectively collected patient data using a standardized questionnaire. The features of patients presenting with skin and soft tissue were then analyzed.

RESULTS

PVL producing S. aureus was isolated from 64 patients. Fifty-four patients presented with skin and soft tissue infections. The mean age of patients was 23.8 years (63% male patients). The mean number of persons living with the infected patient was 4.5 (vs. 2.5 in NPDC). The lesions were abscesses with inflammatory signs in 64.8% of the cases (20% were necrotic). Among the patients, 70.3% carried a methicillin resistant strain. Antibiotics per os were used for 83.3% of patients; the first-line antibiotics were considered inadequate in 53.3% of the cases. Among the patients, 83.3% underwent surgery. Fourteen out of 38 patients with available data had been exposed to antibiotic therapy during the three months before hospital management.

CONCLUSION

Recent exposure to antibiotics and living with a high number of persons are reasons to suspect a PVL producing S. aureus infection in patients with skin abscess.

Cutaneous abscesses in children: epidemiology in the era of methicillin-resistant Staphylococcus aureus in a pediatric emergency department

OBJECTIVE

Skin and soft tissue infections are a major public health issue. Previous literature suggests a recurrence rate of 4% in children. The purpose of this study was to examine the epidemiology, body location, and history of previous infections among children in the emergency department setting.

METHODS

A retrospective study was performed using electronic medical records from all subjects treated in a large pediatric emergency department with attending physician diagnosis and billing codes indicative of a cutaneous abscess from July 1, 2007, to December 31, 2007. Descriptive statistics were used to evaluate abscess location, prior history of infection, bacterial etiology, and patient disposition.

RESULTS

Three hundred eighteen abscess visits occurred in 308 individual subjects; 79% were due to methicillin-resistant Staphylococcus aureus. Approximately 14% of subjects presented with more than 1 abscess. Those 2 years or younger were more likely to have buttock abscesses (P < 0.001). Of the 192 subjects for whom responses were documented, 82 (43%) had a history of a prior abscess. Children 2 years or younger were significantly more likely to be hospitalized or go to the operating room: 49% versus 15% (P < 0.001).

CONCLUSIONS

Many children with a cutaneous abscess have a prior history of infection. Multiple abscesses are common. Young children are more likely to have abscesses in the diaper area or be hospitalized. Studies of effective hygiene practices and interventions to reduce recurrence are urgently needed.

Treatment of MRSA soft tissue infections: an overview

MRSA is becoming increasingly common worldwide. With the emergence of new highly spreadable strains (community associated or CA-MRSA) novel presentation skin and soft tissue infections (SSTI) are being seen. Recurrent SSTI, including folliculitis, furunculosis and abscesses account for an increasing proportion of SSTI seen in the emergency department. Empirical antimicrobial management choices can be difficult, but clues to the nature of the MRSA may be gleaned from the history and clinical presentation. More severe SSTI due to necrotising fasciitis and purpura fulminans are emerging and warrant the broadest possible empirical Gram-positive cover, ideally with antimicrobials that stop exotoxin production, and sometimes intravenous immunoglobulin to neutralise exotoxins already produced.

Differentiating osteoarticular infections caused by Kingella kingae from those due to typical pathogens in young children

Osteoarticular infections caused by Kingella kingae are characterized by mild-to-moderate clinical and biologic inflammatory signs that are different from those caused by Gram-positive cocci. A combined score was built to find the best model to predict K. kingae osteoarticular infections by using the following 4 variables: body temperature <38°C, serum C-reactive protein <55 mg/L, white blood cell count <14,000/mm, and band forms <150/mm.

A nosocomial outbreak of community-associated methicillin-resistant Staphylococcus aureus among healthy newborns and postpartum mothers

BACKGROUND

Community-associated methicillin-resistant Staphylococcus aureus (CA-MRSA) has increasingly been isolated from individuals with no predisposing risk factors; however, such strains have rarely been linked to outbreaks in the hospital setting. The present study describes the investigation of an outbreak of CA-MRSA that occurred in the maternal-newborn unit of a large community teaching hospital in Toronto, Ontario.

METHODS

Screening and clinical specimens collected from mothers and newborns delivered during the outbreak period, as well as from staff on the affected unit, were submitted for microbiological testing. Computerized delivery logs and nursing notes were reviewed, and a case control study was conducted.

RESULTS

Analysis by pulsed-field gel electrophoresis revealed 38 babies and seven mothers with MRSA colonization and/or infection by the same unique strain (Canadian MRSA-10-related) from September to December 2004. Isolates were characterized as having the staphylococcal chromosome cassette mec type IVa and were positive for the Panton-Valentine leukocidin gene. No one health care worker was associated with all cases; however, mothers and newborns exposed to one particular nurse (Nurse A) were almost 23 times (odds ratio 22.7, 95% CI 3.3 to 195.9) more likely to acquire MRSA than those with no such contact. MRSA was successfully isolated from Nurse A and from an environmental swab of a telephone recently used by Nurse A; both isolates matched the pulsed-field gel electrophoresis pattern of the outbreak strain.

CONCLUSION

The first nosocomial outbreak of CA-MRSA among healthy newborns and postpartum mothers in Canada is described. Effective control of sustained MRSA transmission within an institution may require prompt identification, treatment and monitoring of colonized and/or infected staff.

Role of bacterial components in macrophage activation by the LAC and MW2 strains of community-associated, methicillin-resistant Staphylococcus aureus

We tested the contribution of four staphylococcal components - PSM-α, PSM-β, δ-toxin, and PVL - in triggering macrophage secretion of tumor necrosis factor (TNF) and interleukins 6 (IL-6) and 12 (IL-12) by two prominent, circulating strains of community-associated, methicillin-resistant Staphylococcus aureus (CA-MRSA): LAC, USA300; MW2, USA400. RAW 264.7 murine macrophages were stimulated with live, antibiotic-exposed bacteria, and cytokine secretion was quantitated in supernatants. Deletion of PSM-α expression in LAC led to >50% reduction in macrophage TNF and IL-6 secretion and a 20% reduction in IL-12 secretion, while PSM-α deletion in MW2 did not significantly reduce macrophage TNF secretion but resulted in a 15-20% reduction in IL-6 and IL-12 secretion. Deletion of δ-toxin in either strain led to more than 50% reduction in macrophage IL-6 secretion and smaller reductions in macrophage TNF and IL-12 secretion (8-25%). Our data implicate both PSM-α and δ-toxin in stimulating macrophage cytokine responses to CA-MRSA bacteria.

Increasing prevalence of nasal and rectal colonization with methicillin-resistant Staphylococcus aureus in children with cancer

BACKGROUND

Infections with methicillin-resistant Staphylococcus aureus (MRSA), in community-settings, especially with strains carrying the Panton-Valentine Leukocidin (PVL) genes, have increased markedly in recent years. Colonization with S. aureus is a risk factor for infection. However, there are few studies that examine colonization and infection with PVL-positive strains of MRSA in cancer patients.

PROCEDURE

The epidemiology of colonization and infection with MRSA was studied in children with cancer during two time periods: 2000/2001 and 2006/2007. PVL genes were screened and spa typing performed on the isolates.

RESULTS

The prevalence of colonization with MRSA increased from 0.6% in 2000/2001 to 2.9% in 2006/2007 (P = 0.0003). MRSA colonization at admission was associated with infection (P < 0.0001; RR 38.32; 95% CI: 23.36-62.84). The prevalence of infection increased from 0.99% in 2000/2001 to 3.78% in 2006-2007 (P = 0.0002). Of the 32 colonized patients, 18 (56%) had infection. None of the 14 colonized but non-infected patients had dual colonization of nares and rectum, while 8 of the 18 infected patients had colonization of both of these sites (P = 0.004). Ten patients (31%) were colonized with PVL-positive strains. Patients colonized with PVL-positive strains were more likely to be colonized both in the nares and rectum (P = 0.005), and more likely to have infection (P = 0.001). Recurrent MRSA infections were seen in 22% of patients.

CONCLUSION

An increasing prevalence of colonization with MRSA was observed in children with cancer at our institution. Colonization with MRSA especially with PVL-positive strains was associated with infection.

Radiological findings of community-acquired methicillin-resistant and methicillin-susceptible Staphylococcus aureus pediatric pneumonia in Hawaii

BACKGROUND

Community-acquired Staphylococcus aureus (CA-SA) infections are common among pediatric patients in Hawaii.

OBJECTIVE

We wanted to characterize the radiological features of methicillin-susceptible (CA-MSSA) and methicillin-resistant (CA-MRSA) staphylococcal pneumonia in Hawaiian children.

MATERIALS AND METHODS

We retrospectively reviewed medical records and imaging studies of children with SA pneumonia identified from 1996 through 2007.

RESULTS

Of 40 children, 26 (65%) had CA-MRSA pneumonia and 14 patients (35%) had CA-MSSA pneumonia. CA-MRSA patients were significantly younger than CA-MSSA patients (65% younger than 1 year vs. 36% older). In a majority (62%) of CA-MRSA patients, the consolidation was unilateral; in most of the CA-MSSA cases (79%), the consolidation was bilateral. Fifty percent of the patients with CA-MRSA and 21% of those with CA-MSSA had pneumatoceles (P = 0.1). CA-MRSA patients more commonly had pleural effusions (85% vs. 64% for CA-MSSA) and pleural thickening (50% vs. 36% for CA-MSSA).

CONCLUSION

This case series describes the radiologic characteristics of CA-MRSA and CA-MSSA pneumonia in children in a highly endemic area. We found that CA-MRSA pneumonias are unilateral in a majority of pediatric pneumonia cases, are more common in children 1 year or younger, and have higher rates of complications in comparison to CA-MSSA patients.

Community-acquired Staphylococcus aureus pneumonia among hospitalized children in Hawaii

SUMMARY BACKGROUND

Invasive community acquired (CA) Staphylococcus aureus (SA) disease has been endemically observed in Hawaiian children. We wanted to evaluate the clinical, laboratory findings, and outcomes of methicillin-resistant SA (MRSA) and methicillin-susceptible SA (MSSA) associated pneumonia admissions.

METHODS

We performed retrospective chart reviews of 38 culture proven SA pneumonia patients admitted to a pediatric tertiary medical center in Hawaii between January 1996 to December 2007.

RESULTS

Twenty-six patients (68%) had MRSA and 12 patients (32%) had MSSA infection. The mean age of MRSA patients was 2.8 and 6.7 years for MSSA patients (P < 0.05). Pacific Islander and Native Hawaiian patients were affected disproportionately compared to non-Pacific Islander and Hawaiian groups (P < 0.0001). Demographic data, days of fever, tachypnea, hypoxia, and length of stay (LOS) were not significantly different between MRSA and MSSA infected patients. The mean LOS was 26.2 days (range 6-138 days); mean length of fever was 12.4 days. Seventy five percent (15 of 20) of patients who required intubation had MRSA. Twenty-one of the 29 (72%) total patients with pleural effusions had MRSA infection and all required chest tube placements. Two (5%) patients died; both had MRSA infection.

CONCLUSIONS

Younger Pacific Islander/Native Hawaiian children were affected disproportionately and had MRSA infection more frequently. MRSA infected patients appeared to have severe disease with frequent chest tube placement, intubation, and fatality. Overall, both MRSA and MSSA pneumonia resulted in prolonged hospitalization, multiple complications, and significant healthcare costs.

Community-associated methicillin-resistant Staphylococcus aureus: epidemiology and clinical consequences of an emerging epidemic

Staphylococcus aureus is an important cause of skin and soft-tissue infections (SSTIs), endovascular infections, pneumonia, septic arthritis, endocarditis, osteomyelitis, foreign-body infections, and sepsis. Methicillin-resistant S. aureus (MRSA) isolates were once confined largely to hospitals, other health care environments, and patients frequenting these facilities. Since the mid-1990s, however, there has been an explosion in the number of MRSA infections reported in populations lacking risk factors for exposure to the health care system. This increase in the incidence of MRSA infection has been associated with the recognition of new MRSA clones known as community-associated MRSA (CA-MRSA). CA-MRSA strains differ from the older, health care-associated MRSA strains; they infect a different group of patients, they cause different clinical syndromes, they differ in antimicrobial susceptibility patterns, they spread rapidly among healthy people in the community, and they frequently cause infections in health care environments as well. This review details what is known about the epidemiology of CA-MRSA strains and the clinical spectrum of infectious syndromes associated with them that ranges from a commensal state to severe, overwhelming infection. It also addresses the therapy of these infections and strategies for their prevention.

Minimally invasive technique in treatment of complex, subcutaneous abscesses in children

The rising prevalence of community-acquired, methicillin-resistant Staphylococcus aureus (MRSA) has correlated with an escalating number of complex, subcutaneous abscesses in pediatric patients. The purpose of this study was to present a novel technique and early outcome results for the minimally invasive drainage of complex, subcutaneous abscesses.

METHODS

Patients' outcomes from the treatment of complex, subcutaneous abscesses were retrospectively reviewed under institutional review board approval from July 2006 to August 2007 at 2 independent, tertiary care pediatric hospitals. Data on patients' demographics, length of hospital stay, and length of treatment were collected, along with analysis of the isolated organisms. The operative technique uses drainage of the abscess through peripheral stab incisions. Cavity debridement and irrigation is followed by placement of a vessel-loop drain through the drainage incisions. Topical wound care without packing is performed twice a day. Drain removal follows resolution of cellulitis and drainage.

RESULTS

One hundred twenty-eight patients were treated over a 14-month period. The ratio of females to males was 1.25:1. Average patient age was 51.5 months (median, 21 months) and ranged from 5 weeks to 18 years. The average length of hospital stay was 1.5 days, though 30 patients were treated on an outpatient basis. Methicillin-resistant Staphylococcus aureus was identified in 76% of the cultured specimens. Average length of drain use was 9 days (range, 5-29 days). There were no local recurrences of subcutaneous abscesses. There was no morbidity related to the drainage procedures.

CONCLUSION

We present a successful technique for the drainage and treatment of complex abscesses in children with limited, postoperative wound care and no morbidity or recurrence.

Methicillin-resistant Staphylococcus aureus: from the hospital to the community

Infections due to community-associated methicillin---resistant Staphylococcus aureus (CA-MRSA) are becoming more prevalent. CA-MRSA infections have unique epidemiologic features and virulence factors. Compared with health care-associated MRSA (HA-MRSA), most CA-MRSA is clonal type USA300 or 400 and has the Staphylococcal cassette chromosome mec type IV, which carries the mecA gene that encodes for resistance to methicillin and other beta-lactam antibiotics but generally not for other antibiotics. CA-MRSA often contains various virulence factors that may result in tissue necrosis. CA-MRSA clinical presentation includes mostly skin and soft tissue infections and less frequently pneumonia. In many of the small soft tissue abscesses due to CA-MRSA, primary treatment with surgical drainage may result in improvement without antibiotic therapy. Optimal treatment and prevention of CA-MRSA infections are unclear. However, distinction between CA-MRSA and HA-MRSA may be less relevant in the future, as CA-MRSA strains are now diagnosed in the hospital setting.

Staphylococcus aureus osteomyelitis in Hawaii

BACKGROUND

The clinical and laboratory findings and outcomes of methicillin-resistant (MRSA) and methicillin-susceptible (MSSA) Staphylococcus aureus osteomyelitis have not been studied in Hawaii.

METHODS

Retrospective inpatient chart reviews of 62 culture-proven osteomyelitis patients between 1996 and 2007 were performed.

RESULTS

Fifteen patients (24%) had MRSA infection, and 47 patients (76%) had MSSA infection. Length of stay, chronic health problems, total duration of fever, and length of treatment were not significantly different between MRSA- and MSSA-infected patients. The peak erythrocyte sedimentation rate and C-reactive protein values were higher among MRSA infected patients (P values: .009 and .003, respectively).The systemic complication rate was higher in MRSA-infected patients (P value: .018).

CONCLUSIONS

Differing from other pediatric staphylococcal infections in Hawaii, the majority of the patients had MSSA infection. Pacific Islander and Native Hawaiian ethnicities were affected disproportionately and had MRSA infection more frequently. MRSA-infected patients had frequent surgical procedures and systemic complications.

Epidemiology and molecular characteristics of community-associated methicillin-resistant and methicillin-susceptible Staphylococcus aureus from skin/soft tissue infections in a children's hospital in Beijing, China

To evaluate the epidemiology and molecular features of community-associated methicillin-resistant Staphylococcus aureus (CA-MRSA) and methicillin-sensitive S. aureus (MSSA) from children with skin and soft tissue infections (SSTIs) in Beijing, China, prospective community-acquired S. aureus SSTIs surveillance was conducted at the Beijing Children's Hospital, Beijing, China, for a 12-month period from August 1, 2008, to July 30, 2009. Susceptibility to 12 antimicrobials was determined by the agar dilution method. Genotypic characteristics of CA-MRSA isolates were tested by SCCmec typing, spa typing, and multilocus sequence typing. Panton-Valentine leukocidin gene was detected. Of 1104 cases, 31.8% (351) were community-acquired S. aureus. CA-MRSA accounted for 4% (14) of S. aureus. Among 14 CA-MRSA and 120 MSSA isolates tested, 100% and 91.7% were multidrug resistant, respectively. ST59-MRSA-IVa-t437 (42.9%) was the most common form of CA-MRSA. Spa typing analysis of 120 MSSA isolates was performed, followed by pulsed-field gel electrophoresis and multilocus sequence typing of a selected number of isolates. The most common spa types among MSSA were t084 (8.3%), t091 (5.8%), t034 (5%), t127 (4.2%), t002 (4.2%), and t796 (4.2%). No predominant spa type was seen. Of the MSSA isolates that could be classified into spa-CCs, 15.0% had a genetic background observed in CA-MRSA clones (spa-CC437, spa-CC342, and spa-CC377). Panton-Valentine Leukocidin (PVL)-positive community-acquired S. aureus strains were more commonly associated with skin abscesses than other SSTIs (29.4% versus 5.9%, P < 0.01).In conclusion, CA-MRSA infections are not common among Chinese children with SSTIs. Our findings show that MSSA strains in China have diverse genetic backgrounds.

Staphylococcus aureus antimicrobial susceptibility of abscess samples from adults and children from the Kaleida Health System in western New York State, 2003 to 2006

Staphylococcus aureus is the most common etiologic agent of skin abscesses. The regional rate of methicillin-resistant S. aureus (MRSA) abscesses may reflect the prevalence of local community-acquired MRSA (CAMRSA). A retrospective study was conducted to compare the antimicrobial susceptibility patterns of S. aureus isolates recovered from abscesses from 2003 to 2006 from patients at hospitals of the Kaleida Health System in western New York. S. aureus susceptibility information was obtained from a Vitek Legacy system, and the location and source of each isolate were identified. EpiInfo software was used to analyze the antimicrobial susceptibilities of all isolates and the trends in the rates of MRSA. A total of 2,848 S. aureus abscesses were identified by the Kaleida Health Clinical Microbiology Laboratory. Of those, 978 S. aureus abscess events occurred in four hospitals, including three adult facilities (547 episodes with 62 cases of bacteremia) and one children's facility (431 episodes with 2 cases of bacteremia). The MRSA rates in adults increased from 56% (2003) to 71% (2006), and that in children increased from 26% (2003) to 64% (2006). Of the MRSA isolates in the children's samples, more than 92% were susceptible to clindamycin. Of the MRSA isolates in the adult samples, 50% were susceptible to clindamycin in 2003 and 2004, whereas greater than 75% were susceptible in 2005 and 2006. The increased rates of MRSA abscesses with susceptibility to clindamycin may reflect the high prevalence level of CAMRSA in the western New York community. The variations in S. aureus susceptibilities could serve as an indicator of the changing resistance patterns within a broad urban community.

Short communication: methicillin-resistant Staphylococcus aureus infections in children and young adults infected with HIV

The epidemiology of methicillin-resistant Staphylococcus aureus (MRSA) infections, in particular with Panton-Valentine leukocidin (PVL)-positive strains, has not been well characterized in children and young adults with HIV infection. It is not known if PVL-positive strains of MRSA cause an increased morbidity in this population compared to PVL-negative strains. The purpose of this study was to retrospectively analyze the epidemiology of PVL-positive and PVL-negative MRSA infections in children and young adults with HIV from 2000 to 2007. Molecular typing was performed by polymerase chain reaction (PCR) for detection of the PVL genes. Staphylococcus Cassette Chromosome (SCC) mec and spa typing were performed on all PVL-positive isolates. The number of HIV patients with MRSA infection increased significantly between 2000 and 2007 ( p=0.0015). Twenty seven (87%) of the 31 MRSA isolates were from skin and soft tissue infections (SSTI). Clindamycin resistance was observed in 19% of the MRSA isolates. PVL-positive isolates bearing the type IV SCC mec element comprised 16 of 31 (52%) MRSA isolates. All the PVL-positive isolates belonged to the USA300 pulsed-field type. There was no difference in the mean CD4 count and HIV viral load between patients with PVL-positive and PVL-negative MRSA infections. PVL-positive MRSA infections were associated with more SSTI ( p=0.043) but not with increased morbidity or a higher risk of complications compared to PVL-negative MRSA infections in children and young adults with HIV.

Stevens-Johnson syndrome and toxic epidermal necrolysis: consequence of treatment of an emerging pathogen

We report a case of Stevens-Johnson syndrome/toxic epidermal necrolysis (SJS/TEN) secondary to trimethoprim-sulfamethoxazole (TMP-Sx) therapy for presumed community-associated methicillin-resistant Staphylococcus aureus (CA-MRSA) infection. Although the association between SJS/TEN and the sulfonamide class of antibiotics is well established, the increasing prevalence of CA-MRSA has left practitioners with limited regimens to effectively treat skin and soft tissue infections (SSTIs) in the outpatient setting. In the case of SSTIs, alternative treatment of these infections should be considered, especially when the bacterial pathogen is unknown. Future investigations evaluating the efficacy of adjunctive antibiotics for purulent SSTIs and monitoring the incidence of SJS/TEN in the era of CA-MRSA are necessary to reduce unnecessary use of sulfonamide drugs. The potential development of SJS/TEN, a severe life-threatening illness, emphasizes the need for judicious use of TMP-Sx and close monitoring and follow-up for patients who were given TMP-Sx for SSTIs.

Comparative molecular analysis of community-associated and healthcare-associated methicillin-resistant Staphylococcus aureus isolates from children in northern Taiwan

From August 2004 to July 2005, 210 clinical methicillin-resistant Staphylococcus aureus (MRSA) isolates were collected prospectively from 173 children admitted to Chang Gung Children's Hospital in Taiwan. A comparative molecular analysis of the 111 community-associated (CA) isolates from 102 children and the 99 healthcare-associated (HA) isolates from 71 children was conducted. In comparison to the HA isolates (31%), the CA isolates (90%) were more likely to have been isolated from pus (p <5 x 10(-8)). For each patient with MRSA infection, only the first isolate was selected for molecular analysis. The molecular characteristics differed significantly between the CA and the HA isolates (p <5 x 10(-8)). The clone characterized as sequence type (ST)59/pulsotype D (similar to USA1000)/staphylococcal chromosomal cassette (SCC)mec V(T)/Panton-Valentine leukocidin (PVL)-positive accounted for 69% of the CA isolates, and another clone, characterized as ST239/pulsotype A (Hungary clone)/SCCmec III/PVL-negative, accounted for 45% of the 71 HA isolates. The CA clone of ST59 also accounted for 20% of the HA isolates, including 47% of the 17 community-onset isolates. It was concluded that the molecular characteristics of clinical MRSA isolates from children differed significantly between the CA and the HA isolates in northern Taiwan. However, the CA clone of ST59 was also identified in a substantial proportion of HA isolates.

Prevalence of and risk factors for community-acquired methicillin-resistant and methicillin-sensitive staphylococcus aureus colonization in children seen in a practice-based research network

OBJECTIVE

We sought to define the prevalence of and risk factors for methicillin-resistant Staphylococcus aureus nasal colonization in the St Louis pediatric population.

METHODS

Children from birth to 18 years of age presenting for sick and well visits were recruited from pediatric practices affiliated with a practice-based research network. Nasal swabs were obtained, and a questionnaire was administered.

RESULTS

We enrolled 1300 participants from 11 practices. The prevalence of methicillin-resistant S aureus nasal colonization varied according to practice, from 0% to 9% (mean: 2.6%). The estimated population prevalence of methicillin-resistant S aureus nasal colonization for the 2 main counties of the St Louis metropolitan area was 2.4%. Of the 32 methicillin-resistant S aureus isolates, 9 (28%) were health care-associated types and 21 (66%) were community-acquired types. A significantly greater number of children with community-acquired methicillin-resistant S aureus were black and were enrolled in Medicaid, in comparison with children colonized with health care-associated methicillin-resistant S aureus. Children with both types of methicillin-resistant S aureus colonization had increased contact with health care, compared with children without colonization. Methicillin-sensitive S aureus nasal colonization ranged from 9% to 31% among practices (mean: 24%). The estimated population prevalence of methicillin-sensitive S aureus was 24.6%. Risk factors associated with methicillin-sensitive S aureus colonization included pet ownership, fingernail biting, and sports participation.

CONCLUSIONS

Methicillin-resistant S aureus colonization is widespread among children in our community and includes strains associated with health care-associated and community-acquired infections.

Linezolid versus glycopeptide or beta-lactam for treatment of Gram-positive bacterial infections: meta-analysis of randomised controlled trials

Linezolid has been approved for the treatment of patients with infections caused by Gram-positive cocci that are resistant to traditionally used antibiotics, including glycopeptides. This oxazolidinone antibiotic has been reported to have excellent pharmacokinetics and effectiveness. We did a meta-analysis of randomised controlled trials (RCTs) to clarify whether linezolid is superior to glycopeptides or beta-lactams for the treatment of Gram-positive infections. 12 RCTs, involving 6093 patients, were included. Overall, with respect to treatment success, linezolid was more effective than glycopeptides or beta-lactams (odds ratio [OR] 1.41 [95% CI 1.11-1.81]). Mortality was similar between the groups (OR 0.97 [0.79-1.19]). Linezolid was more effective than comparators in patients with skin and soft-tissue infections (OR 1.67 [1.31-2.12]) and bacteraemia (OR 2.07 [1.13-3.78]). However, there was no difference in treatment success for patients with pneumonia (OR 1.03 [0.75-1.42]). Treatment with linezolid was not associated with more adverse effects in general (OR 1.40 [0.95-2.06]); however, thrombocytopenia was recorded more commonly in patients receiving linezolid (OR 11.72 [3.66-37.57]). Although linezolid is more effective than its comparators for the empirical treatment of selected patients, several points, such as the use of less potent antistaphylococcal beta-lactams, the same all-cause mortality, and the higher probability of thrombocytopenia, should be taken into account and may limit the use of linezolid to specific patient populations or infections that are difficult to treat with other antibiotics.

Community-acquired methicillin-resistant Staphylococcus aureus skin infections: implications for patients and practitioners

Dermatologists and other healthcare providers need to be aware of the epidemiology, clinical features, management, and prevention of community-acquired methicillin-resistant Staphylococcus aureus (CAMRSA) infection. Currently, infection caused by CAMRSA is considered to represent a worldwide epidemic and infectious skin lesions are a frequent occurrence. Athletes, certain ethnic populations, children, homeless persons, homosexual men, household members of infected people, HIV-infected patients, intravenous drug abusers, military personnel, newborns, pregnant and postpartum women, tattoo recipients, and urban dwellers of lower socioeconomic status in crowded living conditions are individuals at increased risk of developing CAMRSA infection. Although the observed incidence of cutaneous CAMRSA lesions in patients with atopic dermatitis or other conditions that are characterized by a non-intact skin barrier is less than that reported in other groups of people at risk for this skin infection, close surveillance for the emergence of CAMRSA skin infection in children and adults with atopic dermatitis and other patients whose skin barrier is disrupted is justified since colonization by S. aureus in these individuals represents a potential reservoir for CAMRSA. It is also important to note that infection-associated risk factors are absent in many individuals who develop cutaneous CAMRSA infection. CAMRSA skin lesions are pleomorphic. The most common presentations of CAMRSA infection are abscess, cellulitis, or both. These infectious lesions are not uncommonly misinterpreted by the patient as spider bites or insect bites. Other manifestations of cutaneous CAMRSA infection are impetigo, folliculitis, and paronychia. Incision and drainage of abscesses, systemic antibacterial therapy, and adjunctive topical antibacterial treatment are the essential components of management of CAMRSA skin infections. At the initial visit, a bacterial culture of the infectious lesion is recommended to confirm identification of the pathogen and to determine antimicrobial susceptibility. Subsequently, based upon the reported antibacterial sensitivity, alteration (if necessary) of the patient's empiric systemic antimicrobial treatment can be initiated. Direct skin-to-skin transmission of the causative bacteria, damage to the skin's surface, sharing of personal items, and a humid environment are potential mechanisms for the acquisition and transmission of CAMRSA skin infection. The spread of cutaneous CAMRSA infection can potentially be prevented by incorporating personal, environmental, and healthcare measures that strive to eliminate the causes of acquisition and transmission of the bacteria.

National prevalence of methicillin-resistant Staphylococcus aureus in inpatients at US health care facilities, 2006

BACKGROUND

Despite methicillin-resistant Staphylococcus aureus (MRSA) being endemic in virtually all US health care facilities, there are no data on the prevalence of MRSA in US health care facilities.

METHODS

We conducted a national prevalence survey of MRSA in inpatients at US health care facilities. The survey was developed, received institutional review board approval, and then distributed to all members of the Association for Professionals in Infection Control and Epidemiology, Inc. (APIC). Members were asked to complete the survey on one day during the period October 1 to November 16, 2006, reporting the number of inpatients with MRSA infection or colonization and facility-specific information.

RESULTS

Personnel at 1237 hospitals completed the survey. Complete facility data were provided for 1187 (96%) of these health care facilities. All states were represented (mean, 23 facilities per state; range, 1-99). Respondents reported 8654 MRSA-colonized/infected patients in 187,058 inpatients; the overall MRSA prevalence rate was 46.3 per 1000 inpatients (34 infections and 12 colonizations per 1000 inpatients). Active MRSA surveillance testing was conducted by 29% of respondents: 54% used routine media, 38% used selective media, and 8% used polymerase chain reaction. Detailed data were provided on 7994 (92.4%) MRSA-colonized/infected patients. Our data suggest that approximately 70% of isolates were more consistent with health care-associated MRSA (HA-MRSA) than community-associated MRSA.

CONCLUSION

Our survey documents a much higher MRSA prevalence rate than previous studies using different methodologies. The majority of MRSA in inpatients appears to be HA-MRSA. Given that most facilities did not perform active surveillance testing, these are minimum estimates of the national burden of MRSA in US health care facilities.

Update on clindamycin in the management of bacterial, fungal and protozoal infections

Lincomycin and clindamycin are the only members of the relatively small lincosamide antimicrobial class marketed for use in humans. This paper only reviews data regarding clindamycin, with an emphasis on data published over the last decade. Clindamycin exhibits a broad spectrum of antimicrobial activity, including Gram-positive aerobes/anaerobes, Gram-negative anaerobes and select protozoa (Toxoplasma gondii, Plasmodium falciparum, Babesia spp.) and fungi (Pneumocystis jiroveci). It still enjoys use in the therapy and prophylaxis of a large number of bacterial, protozoal and fungal infections, despite > 40 years of clinical use. However, the spectre of resistance by an increasing number of microorganisms is beginning to cast a shadow over the future use of this valuable agent. With the emergence and spread of infections due to community-acquired methicillin-resistant Staphylococci (for which clindamycin is a first-line agent), it is hoped that the issues of resistance can be mitigated and the use of clindamycin extended for at least the foreseeable future.

Prevalence of methicillin-resistant Staphylococcus aureus nasal colonization among Taiwanese children in 2005 and 2006

From July 2005 to October 2006, a total of 3,046 children, of ages between 2 months and 5 years, presented for a well-child health care visit to one of three medical centers, which are located in the northern, central, and southern parts of Taiwan, and were surveyed for nasal carriage of methicillin-resistant Staphylococcus aureus (MRSA). The overall prevalences of S. aureus and MRSA nasal carriage among the children were 23% and 7.3%, respectively (18% and 4.8% in the central region, 25% and 6.7% in the southern region, and 27% and 9.5% in the northern region). Of the 212 MRSA isolates (96%) available for analysis, a total of 10 pulsed-field gel electrophoresis (PFGE) patterns with two major patterns (C [61%] and D [28%]) were identified. One hundred forty-nine isolates (70%) contained type IV staphylococcal cassette chromosome mec (SCCmec) DNA, and 55 isolates (26%) contained SCCmec V(T). The presence of Panton-Valentine Leukocidin (PVL) genes was detected in 60 isolates (28%). Most MRSA isolates belonged to one of two major clones, characterized as sequence type 59 (ST59)/PFGE C/SCCmec IV/absence of PVL genes (59%) and ST59/PFGE D/SCCmec V(T)/presence of PVL genes (25%). We concluded that between 2005 and 2006, 7.3% of healthy Taiwanese children were colonized by MRSA in nares. MRSA harbored in healthy children indicates an accelerated spread in the community.

Nasal carriage of a single clone of community-acquired methicillin-resistant Staphylococcus aureus among kindergarten attendees in northern Taiwan

Background:

To evaluate the prevalence and microbiological characterization of community-acquired (CA) methicillin-resistant Staphylococcus aureus (MRSA) nasal carriage in a kindergarten.

Methods:

Point prevalence study. Nasal swabs were collected from healthy children younger than 7 years of age who were attending a kindergarten in Taipei, Taiwan. A parent questionnaire regarding MRSA risk factors was administered simultaneously. All CA-MRSA colonization isolates were archived for subsequent antimicrobial susceptibility and molecular typing.

Results:

Of the 68 children who participated in the study, 17 (25%) had S. aureus isolated from nasal swabs. Nine (13.2%) of the 68 children had CA-MRSA carriage, and none of them had any identified risk factors. Antimicrobial susceptibility testing revealed all of the 9 CA-MRSA colonization isolates had uniformly high resistance (100%) to both clindamycin and erythromycin, the macrolide-lincosamide-streptogramin-constitutive phenotype and the ermB gene. Pulsed-field gel electrophoresis revealed 8 (88.9%) of 9 CA-MRSA colonization isolates were genetically related and multilocus sequence typing revealed all isolates had sequence type 59. All of the colonization isolates carried the staphylococcal cassette chromosome mec type IV, but none were positive for the Panton-Valentine leukocidin genes.

Conclusion:

The results of this study suggest that a single predominant CA-MRSA colonization strain featuring high clindamycin resistance circulated in this kindergarten. Additionally, due to the established transmissibility of colonization isolates, the high prevalence of nasal carriage of CA-MRSA among healthy attendees in kindergartens may indicate the accelerated spread of CA-MRSA in the community.

Methicillin-resistant Staphylococcus aureus (MRSA) in foods of animal origin product in Italy

Methicillin-resistant Staphylococcus aureus (MRSA) strains are a global health concern. The present study regarded 160 S. aureus strains that had been isolated from 1634 foodstuff samples of animal origin in a previous survey conducted in Italy during 2003-2005. The strains were characterized by detecting the mecA gene, the production of type A to D staphylococcal enterotoxins (SEs), and studying their resistance properties against several antibiotics; their ecological origin was determined by biotyping. Of the 160 analyzed S. aureus strains six (3.75%) were mecA positive and derived from six different samples; four isolates were from bovine milk and two from dairy products (pecorino cheese and mozzarella cheese). Two strains isolated from milk belonged to the non-host-specific biovar while the others to the ovine biovar. The strain isolated from mozzarella cheese belonged to the non-host-specific biovar and the strain isolated from pecorino cheese to the ovine biovar. All the MRSA strains isolated were enterotoxigenic; two strains synthesized SEA/SED two SED and one SEC. All the strains showed resistance to at least one of the antibiotics tested but none was resistant to glycopeptides.

Knockout of Mkp-1 enhances the host inflammatory responses to gram-positive bacteria

MAPK phosphatase (MKP)-1 is an archetypal member of the dual specificity protein phosphatase family that dephosphorylates MAPK. We have previously demonstrated that MKP-1 acts as a negative regulator of p38 and JNK in immortalized macrophages after stimulation with peptidoglycan isolated from Gram-positive bacteria. To define the physiological function of MKP-1 during Gram-positive bacterial infection, we studied the innate immune responses to Gram-positive bacteria using Mkp-1 knockout (KO) mice. We found that Mkp-1(-/-) macrophages exhibited prolonged activation of p38 and JNK, but not of ERK, following exposure to either peptidoglycan or lipoteichoic acid. Compared with wild-type (WT) macrophages, Mkp-1(-/-) macrophages produced more proinflammatory cytokines such as TNF-alpha and IL-6. Moreover, after challenge with peptidoglycan, lipoteichoic acid, live or heat-killed Staphylococcus aureus bacteria, Mkp-1 KO mice also mounted a more robust production of cytokines and chemokines, including TNF-alpha, IL-6, IL-10, and MIP-1alpha, than did WT mice. Accordingly, Mkp-1 KO mice also exhibited greater NO production, more robust neutrophil infiltration, and more severe organ damage than did WT mice. Surprisingly, WT and Mkp-1 KO mice exhibited no significant difference in either bacterial load or survival rates when infected with live S. aureus. However, in response to challenge with heat-killed S. aureus, Mkp-1 KO mice exhibited a substantially higher mortality rate compared with WT mice. Our studies indicate that MKP-1 plays a critical role in the inflammatory response to Gram-positive bacterial infection. MKP-1 serves to limit the inflammatory reaction by inactivating JNK and p38, thus preventing multiorgan failure caused by exaggerated inflammatory responses.

Successful use of extracorporeal membrane oxygenation in severe necrotizing pneumonia caused by Staphylococcus aureus

OBJECTIVE

To report the successful use of extracorporeal membrane oxygenation (ECMO) as rescue therapy for severe necrotizing pneumonia secondary to infection by the Staphylococcus aureus species.

DESIGN

Case series.

SETTING

Pediatric intensive care unit at a freestanding tertiary care children's hospital.

PATIENTS

Two pediatric patients with severe S. aureus-induced necrotizing pneumonia requiring rescue with ECMO. Both patients survived with good neurologic outcomes. One patient required the use of activated factor VII for severe bleeding while on ECMO, with no thrombotic effect on the ECMO circuit.

CONCLUSION

ECMO as rescue support should be considered in a timely fashion for refractory hypoxemic respiratory failure resulting from S. aureus pneumonia, including patients with necrotizing pneumonia. Use of ECMO support in such cases, coupled with aggressive measures aimed at minimizing bleeding, such as the use of activated factor VII, may result in excellent short- and long-term outcomes for such patients.

Comparison of community-acquired methicillin-resistant Staphylococcus aureus bacteremia to other staphylococcal species in a neonatal intensive care unit

Hospital acquired infections including staphylococcal species are common in neonatal intensive care units. Community-associated methicillin-resistant Staphylococcus aureus (CA-MRSA) was recently observed in our unit. The clinical and laboratory characteristics of all neonates with Staphylococcus aureus bacteremia during an 11-year period were retrospectively reviewed. Three groups of patients were compared: 1. Patients with CA-MRSA defined as MRSA-resistant only to beta-lactams, but sensitive to all other antibiotic groups and carried SCCmec IV. 2. Patients with multi-drug-resistant (MDR)-MRSA and 3. Patients with MSSA (methicillin-sensitive S. aureus). Forty-three neonates with documented S. aureus bacteremia were included. Of these 41 were preterm babies. Eleven infants had CA-MRSA, 20 had MDR-MRSA and 12 had MSSA bacteremia, the Panton-Valentine-Leukocidine gene (pvl-gene) was not present in any of these strains. Risk factors, clinical manifestations and laboratory tests were similar in all three groups studied. Although neonates infected with CA-MRSA were more premature and had more related diseases, the mortality rate was similar in all groups (9.1% in the CA-MRSA group). Skin infections, osteomyelitis or pneumatocele were not observed more frequently in the CA-MRSA group. We did not find significant differences in risk factors or outcomes in neonates in the three groups. One possible explanation for this observation is that the CA-MRSA outbreak strain did not contain the pvl-gene, which has been suggested to be a significant virulence factor.

Epidemiology of methicillin-resistant Staphylococcus aureus at a pediatric healthcare system, 1991-2003

BACKGROUND

The emergence and epidemiology of methicillin-resistant Staphylococcus aureus (MRSA) at a Minneapolis pediatric healthcare facility was investigated.

METHODS

Children with MRSA infections from January 1991 to December 2003 were classified as community-associated (CA) or healthcare-associated (HA) using established criteria. Isolates were subtyped using pulsed-field gel electrophoresis and grouped into pulsed-field types (PFTs). Case and isolate characteristics were compared and temporal trends were assessed.

RESULTS

The first isolate classified as CA-MRSA in this healthcare facility was identified in 1991. CA-MRSA cases (n = 188) were more likely than HA-MRSA cases (n = 83) to have a skin or soft tissue infection (80% versus 59%) and to belong to a racial or ethnic minority group (82% versus 55%), whereas HA-MRSA cases were younger (median age, 3.4 years versus 4.9 years). The proportion of both CA- and HA-MRSA isolates susceptible to clindamycin and erythromycin declined during the study period. Isolates classified as CA-MRSA were more likely than HA-MRSA isolates to be USA300 (21% versus 11%, P = 0.05) and USA400 (62% versus 31%, P < 0.001) PFTs. Associations between case race/ethnicity and isolate PFT were observed independent of case classification.

CONCLUSIONS

CA-MRSA is well established in this pediatric population. Although no discernable changes in CA- or HA-MRSA case characteristics were documented during the study period, significant changes were observed in CA-MRSA isolate characteristics, indicating that this pathogen continues to evolve.

Changing patterns of acute hematogenous osteomyelitis and septic arthritis: emergence of community-associated methicillin-resistant Staphylococcus aureus

INTRODUCTION

An increase in the incidence and severity of acute osteoarticular infections in children was perceived after the emergence of community-associated methicillin-resistant Staphylococcus aureus (MRSA) in our community. This study was performed to describe changes in the epidemiology and clinical features of acute osteoarticular infections.

METHODS

The records of patients discharged from Le Bonheur Children's Medical Center with a diagnosis of acute osteoarticular infection between 2000 and 2004 were reviewed. Data regarding signs and symptoms, diagnostic testing, therapeutics, surgery, and hospital course were collected.

RESULTS

There were 158 cases of acute osteoarticular infection. The incidence increased from 2.6 to 6.0 per 1000 admissions between 2000 and 2004. The proportion of infections caused by methicillin-susceptible S. aureus (MSSA) remained constant (10%-13%) and that caused by MRSA rose from 4% to 40%. There was no difference between MRSA and MSSA patients in the duration of fever or pain before diagnosis. Seventy-one percent of patients with MRSA had subperiosteal abscesses compared with 38% with MSSA (P = 0.02). Ninety-one percent of MRSA patients required a surgical procedure compared with 62% of MSSA patients (P < 0.001). Median hospital stay was 7 days for MSSA patients and 10 days for MRSA patients (P = 0.0001). Three patients developed chronic osteomyelitis, 2 with MRSA. There was no association between a delay in institution of appropriate antibiotic therapy and presence of subperiosteal abscess (P = 0.8).

CONCLUSIONS

There has been an increase in the incidence and severity of acute osteoarticular infections in Memphis. Patients with community-associated MRSA infections are at higher risk of subperiosteal abscess requiring surgical intervention.

Management of Community-Associated Methicillin-ResistantStaphylococcus aureusInfections in Children

In recent years, community-associated methicillin-resistant Staphylococcus aureus (CA-MRSA) has emerged as a pathogen in children without established risk factors, and its prevalence in the United States is increasing. Although many CA-MRSA infections are mild, primarily involving the skin and soft tissues, the organism can cause serious, invasive, and life-threatening infections. To provide a comprehensive review of the epidemiology, clinical features, therapy, and prevention of CA-MRSA infections in children, we performed MEDLINE (1966-January 2006) and Cochrane Library searches, and reviewed abstracts for relevance to S. aureus infections. Only articles pertaining to CA-MRSA infections in pediatrics were closely examined. As a genetically distinct pathogen, CA-MRSA is generally susceptible to multiple non-beta-lactam antimicrobials. The optimal treatment for CA-MRSA infections in pediatric patients has not been well studied. Common antibiotics used include clindamycin, trimethoprim-sulfamethoxazole, vancomycin, and rifampin. Rational empiric antimicrobial therapy for infections caused by S. aureus requires consideration of the possibility of methicillin resistance. The local prevalence and susceptibilities of CA-MRSA, severity of infection, and individual risk factors should be considered in selecting treatment.

Evolving epidemiology of pediatric Staphylococcus aureus cutaneous infections in a Baltimore hospital

OBJECTIVES

To examine the epidemiology, antibiotic susceptibility profiles, and outcomes in pediatric Staphylococcus aureus (SA) cutaneous infections at a time when community-associated (CA) methicillin-resistant SA (CA-MRSA) infections seemed to be increasing in our community.

METHODS

The hospital microbiology database was searched for unique skin and wound SA isolates among pediatric patients between November 2002 and October 2003. Demographic and clinical data were abstracted from medical records. Cases were classified as either health care-associated (HA) or CA.

RESULTS

Among 181 pediatric SA cutaneous infections, 81 (45%) were caused by MRSA. Most (84%) of these MRSA were CA. Between the first 6 months and second 6 months of the study period, CA-MRSA increased from 15% to 45% (P < 0.001) of all SA cutaneous infections. Ninety-eight percent and 94% of CA-MRSA were susceptible to trimethoprim/sulfamethoxazole and clindamycin (confirmed by D test), respectively. Hospitalization occurred for 25% of CA-MRSA and 75% of HA-MRSA (P = 0.004). Drainage procedures were performed for 70% of CA-MRSA. No cases of CA-MRSA skin infections were accompanied by bacteremia.

CONCLUSIONS

The CA-MRSA cutaneous infections increased in children in our urban Baltimore hospital in 2003. These CA-MRSA were erythromycin resistant, clindamycin susceptible, and trimethoprim/sulfamethoxazole susceptible. The CA-MRSA cutaneous infections frequently required drainage and were not associated with bacteremia. Children with cutaneous MRSA infections were less likely to have traditional health care risk factors than children with cutaneous methicillin-sensitive SA infections--an inversion of past patterns of MRSA infections--but were equally likely to be hospitalized when other factors were considered. These CA-MRSA cutaneous infections can be managed with abscess drainage and culture, careful follow-up, and empirical clindamycin therapy when clinically indicated.

Healthy children with invasive community-acquired methicillin-resistant Staphylococcus aureus infections

Reports of community-acquired methicillin-resistant Staphylococcus aureus (CA-MRSA) infections in the pediatric community have exploded during the past decade. These infections typically result in mild skin and soft tissue infections that can be managed simply with oral antimicrobials. Recently, there have been reports of invasive CA-MRSA infecting children without risk factors, with isolated cases of life-threatening disease. We report 2 atypical cases of invasive CA-MRSA infecting previously healthy children.

Staphylococcal skin infections in children: rational drug therapy recommendations

Staphylococcus aureus remains one of the most common and troublesome of bacteria causing disease in humans, despite the development of effective antibacterials and improvement in hygiene. The organism is responsible for over 70% of all skin and soft tissue infections in children and accounts for up to one-fifth of all visits to pediatric clinics. Skin and soft tissue infections that are predominantly caused by S. aureus include bullous and non-bullous impetigo, folliculitis, furunculosis, carbunculosis, cellulitis, surgical and traumatic wound infections, mastitis, and neonatal omphalitis. Other skin and soft tissue infections may also be caused by S. aureus but are often polymicrobial in origin and require special consideration. These include burns, decubitus ulcers (particularly in the perianal region), puncture wounds of the foot, as well as human and mammalian bites. Treatment of staphylococcal skin infections varies from topical antiseptics to prolonged intravenous antibacterials, depending on severity of the lesions and the health of the child. The treatment of choice for oral antibacterials remains the penicillinase-resistant penicillins such as flucloxacillin. Cefalexin and erythromycin are suitable cost-effective alternatives with broader cover, although care must be taken with the use of macrolides because of development of resistance to multiple families of antibacterials, particularly the lincosamides. Other cephalosporins such as cefadroxil and cefprozil are also effective, can be given once daily and have a better tolerability profile -- while azithromycin has a further advantage of a 3-day course. However, all of these agents are more expensive. Although the antibacterials have been given for 10 days in most clinical trials, there is no evidence that this duration is more effective than a 7-day course. In children requiring intravenous therapy, ceftriaxone has a major advantage over other antibacterials such as sulbactam/ampicillin and cefuroxime in that it can be given once daily and may, therefore, be suitable for outpatient treatment of moderate-to-severe skin infections. Newer-generation cephalosporins and loracarbef are also effective and have a broader spectrum of activity, but do not offer any added benefit and are significantly more expensive. Skin and soft tissue infections due to methicillin-resistant S. aureus (MRSA) are still relatively uncommon in children. Well children with community-acquired MRSA infections can be treated with clindamycin or trimethoprim-sulfamethoxazole (cotrimoxazole), but must be observed closely for potentially severe adverse effects. In severe infections, vancomycin remains the treatment of choice, while intravenous teicoplanin and clindamycin are suitable alternatives. Linezolid and quinupristin/dalfopristin are currently showing great promise for the treatment of multi-resistant Gram-positive infections. While the choice of antibacterial is important, supportive management, including removal of any infected foreign bodies, surgical drainage of walled-off lesions, and regular wound cleaning, play a vital role in ensuring cure.

[Emergence of a single clone of community-associated methicillin-resistant Staphylococcus aureus in southern Madrid children]

INTRODUCTION

The observation of an increasing number of methicillin-resistant Staphylococcus aureus (MRSA) isolated from children prompted us to study the microbiological, epidemiological and clinical characteristics of these isolates. The possibility of some of them being community-acquired focused particularly our attention.

METHODS

A retrospective analysis of all children with MRSA isolated at the Doce de Octubre hospital between January 2002 and June 2005 was conducted. Infections were classified as community-acquired, hospital-acquired, or health-care associated. Isolates of MRSA were studied by pulsed-field gel electrophoresis (PFGE) and SSCmec typing. The presence of the gene encoding the Panton-Valentine leukocidin was also detected by PCR.

RESULTS

MRSA were isolated from 17 patients. Seven isolates (42.2%) were community-acquired, corresponding to four cases of skin or soft-tissue infections, two otitis cases and one bacteremic pyomyositis. Six of seven community-acquired isolates had the same ECP pattern (genotype D), presented a type IV SSCmec, and were LPV toxin-producing and methicillin-resistant with no other associated resistances.

CONCLUSION

To our knowledge, this study shows the presence of these community-acquired MRSA strains for the first time in Spain. The evidence of an apparently clonal spreading of community-acquired MRSA infections in children has important implications for public health and treatment strategies.

Economic impact of the community-acquired methicillin-resistant Staphylococcus aureus epidemic on the Driscoll Children's Health Plan

Cellulitis and abscess accounted for increasing percentages of inpatient (4.6-11.1%), outpatient (0.6-1.2%) and total (1.7-3.3%) expenses from 2001 through 2004. The per member per month expenses attributed to cellulitis and abscess increased from $0.74 in 2001 to $1.19 in 2004. The epidemic of community-acquired methicillin-resistant Staphylococcus aureus infections in children has had a significant economic impact on the Driscoll Children's Health Plan.