Management and outcome of children with skin and soft tissue abscesses caused by community-acquired methicillin-resistant Staphylococcus aureus

Treatment strategies for methicillin-resistant Staphylococcus aureus infections in pediatrics

Staphylococcus aureus is an important pathogen that frequently causes clinical disease in children. A wide array of illnesses can be caused by this common pathogen ranging from non-invasive skin infections to severe, life-threatening sepsis. Additionally, as antibacterials have been used to eradicate S. aureus, it has developed resistance to these important therapeutic agents. Methicillin-resistant S. aureus (MRSA) has become an increasing problem in pediatric patients over the past decade. In this review, we discuss the epidemiology, pathogenesis, and treatment options available in treating MRSA infections in children. Specifically, we address the importance of abscess drainage in the treatment of skin and soft tissue infections, the most common clinical manifestation of MRSA infections, and highlight the various agents that are available for treating this common infection. In severe, life-threatening invasive MRSA infections the primary therapeutic option is vancomycin. In cases of MRSA toxic shock syndrome the addition of clindamycin is necessary. In other invasive MRSA infections, such as pneumonia and musculoskeletal infections, the empiric treatment of choice is clindamycin. Finally, newer agents and additional treatment options are discussed.

Staphylococcus aureus bacteraemia in a tropical setting: patient outcome and impact of antibiotic resistance

Background

Most information on invasive Staphylococcus aureus infections comes from temperate countries. There are considerable knowledge gaps in epidemiology, treatment, drug resistance and outcome of invasive S. aureus infection in the tropics.

Methods

A prospective, observational study of S. aureus bacteraemia was conducted in a 1000-bed regional hospital in northeast Thailand over 1 year. Detailed clinical data were collected and final outcomes determined at 12 weeks, and correlated with antimicrobial susceptibility profiles of infecting isolates.

Principal Findings

Ninety-eight patients with S. aureus bacteraemia were recruited. The range of clinical manifestations was similar to that reported from temperate countries. The prevalence of endocarditis was 14%. The disease burden was highest at both extremes of age, whilst mortality increased with age. The all-cause mortality rate was 52%, with a mortality attributable to S. aureus of 44%. Methicillin-resistant S. aureus (MRSA) was responsible for 28% of infections, all of which were healthcare-associated. Mortality rates for MRSA and methicillin-susceptible S. aureus (MSSA) were 67% (18/27) and 46% (33/71), respectively (p = 0.11). MRSA isolates were multidrug resistant. Only vancomycin or fusidic acid would be suitable as empirical treatment options for suspected MRSA infection.

Conclusions

S. aureus is a significant pathogen in northeast Thailand, with comparable clinical manifestations and a similar endocarditis prevalence but higher mortality than industrialised countries. S. aureus bacteraemia is frequently associated with exposure to healthcare settings with MRSA causing a considerable burden of disease. Further studies are required to define setting-specific strategies to reduce mortality from S. aureus bacteraemia, prevent MRSA transmission, and to define the burden of S. aureus disease and emergence of drug resistance throughout the developing world.

Ultrasound soft-tissue applications in the pediatric emergency department: to drain or not to drain?

Soft tissue infections frequently prompt visits to the pediatric emergency department. The incidence of these infections has increased markedly in recent years. The emergence of community-acquired methicillin-resistant Staphylococcus aureus is associated with an increasing morbidity, mortality, and frequency of abscess formation. Bedside ultrasound may have a significant impact in the management of patients that present to the pediatric emergency department with soft tissue infections, including cellulitis, cutaneous abscess, peritonsillar abscess, and necrotizing fasciitis. Ultrasound is an efficient, noninvasive diagnostic tool which can augment the physician's clinical examination. Ultrasound has been shown to be superior to clinical judgment alone in determining the presence or the absence of occult abscess formation, ensuring appropriate management and limiting unnecessary invasive procedures.

Trimethoprim-sulfamethoxazole or clindamycin for treatment of community-acquired methicillin-resistant Staphylococcus aureus skin and soft tissue infections

The outcome of patients who were treated with oral trimethoprim-sulfamethoxazole or oral clindamycin after hospitalization at Texas Children's Hospital for community-acquired methicillin-resistant Staphylococcus aureus skin and soft tissue infections was compared. No significant differences were observed in the percentage of patients who returned to the emergency center or clinics because of worsening or incomplete resolution of the infected site.

Fever and Rash: A Changing Landscape in the 21st Century

Although “fever and rash” is a common complaint in the pediatric emergency department, most causes are benign. Of the more severe causes, several have been greatly reduced by vaccination programs. In addition, new vaccines such as those for invasive meningococcal disease hold promise for an even brighter future. Although meningococcemia remains an important concern when evaluating a child with fever and a rash, the resurgence of measles, the emergence of invasive group A streptococcal disease and antibiotic-resistant Staphylococcus aureus, as well as the fear of agents of bioterrorism (anthrax, smallpox) have changed the landscape of fever and rash in the 21st century. The purpose of this article is not to offer a comprehensive differential of febrile exanthema, but rather to highlight some new concerns related to the evaluation of fever and rash in today's emergency department.

Changing trends in acute osteomyelitis in children: impact of methicillin-resistant Staphylococcus aureus infections

BACKGROUND

Staphylococcus aureus remains the most common etiologic agent of acute osteomyelitis in children. Recently, methicillin-resistant S. aureus (MRSA) has emerged as a major pathogen.

METHODS

Records of all children admitted with acute osteomyelitis from January 1999 to December 2003 were reviewed. For the comparative analysis, the study population was evenly distributed in 2 periods: period A, January 1999 to June 2001; n = 113; and period B, July 2001 to December 2003; n = 177. In addition, clinical findings of MRSA osteomyelitis were compared with non-MRSA osteomyelitis, including methicillin-sensitive S. aureus infections.

RESULTS

Two hundred ninety children (60% male subjects) with acute osteomyelitis were identified. Median (25th-75th percentile) age at diagnosis was 6 years (range, 2-11 years). Significant clinical findings included the following: localized pain (84%), fever (67%), and swelling (62%). Affected bones included the following: foot (23%), femur (20%), tibia (16%), and pelvis (7%). Thirty-seven percent of blood cultures were positive, and a bacterial isolate was obtained in 55% of cases. Bacteria most frequently isolated included the following: methicillin-sensitive S. aureus (45%) (57% in period Avs 40% in period B), MRSA (23%) (6% in A vs 31% in B; P < 0.001), Streptococcus pyogenes (6%), and Pseudomonas aeruginosa (5%). Children with MRSA compared with those with non-MRSA osteomyelitis had significantly greater erythrocyte sedimentation rate and C-reactive protein values on admission and increased length of hospital stay, antibiotic therapy, and overall rate of complications. We observed significant changes in antibiotic therapy related to increased use of agents with activity against MRSA.

CONCLUSIONS

Methicillin-resistant S. aureus was isolated more frequently in the second study period and was associated with worse clinical outcomes.

Hypochlorite killing of community-associated methicillin-resistant Staphylococcus aureus

We tested in vitro hypochlorite (bleach) killing of community-associated methicillin-resistant Staphylococcus aureus isolates to determine optimal concentration and duration. For all isolates maximal killing, >3-log decrease in colony forming units (CFU), was found after 5 minutes in 2.5 microL/mL bleach. We estimate that 2.5 microL/mL bleach is approximately one-half cup of bleach in one-quarter tub of water.

Management and Treatment Considerations for Infections Caused by Methicillin-Resistant Staphylococcus aureus

Infections caused by methicillin-resistant Staphylococcus aureus have been documented since the 1960s. Four decades later, this microorganism has evolved from a pathogen found primarily in the health care environment to a major pathogen of community-acquired infections. Interestingly, the community-acquired methicillin-resistant Staphylococcus aureus isolates tend to be genetically distinct from their health-care–acquired relatives, have a propensity to be more virulent, yet be susceptible to more antibiotics. Furthermore, infections caused in the pediatric population have a susceptibility pattern that differs from those found in adults. With an increase in infections caused by methicillin-resistant Staphylococcus aureus, empiric therapy should contain an agent with activity against this microorganism. Currently several options exist for the treatment of skin and skin structure infections, yet very few options are available for the treatment of more invasive diseases caused by methicillin-resistant Staphylococcus aureus. This article will review the history of methicillin-resistant Staphylococcus aureus, Staphylococcus aureus economic considerations, and the current plus future treatment options for these infections.

Community-Associated Methicillin-Resistant Staphylococcus aureus in the Pediatric Population

PURPOSE

To review the epidemiology and prevalence of community-associated methicillin-resistant Staphylococcus aureus (CA-MRSA), define the differences between community-acquired and hospital-acquired strains, highlight the advantages and disadvantages of antibiotics commonly used to treat infections caused by this pathogen, and identify strategies to limit the spread of this organism and prevent future outbreaks.

DATA

Literature was accessed through MEDLINE using the search terms community-acquired methicillin-resistant Staphylococcus aureus, community-associated methicillin-resistant Staphylococcus aureus, CA-MRSA, pediatrics, and children. Articles evaluated were published in the English language and limited to human studies. References of literature identified by initial search techniques were reviewed for additional relevant articles.

DATA SYNTHESIS

Community-associated methicillin-resistant Staphylococcus aureus has become a prominent pathogen in pediatric patients in the last ten years. Its increasing prevalence has been reported throughout the United States, and it is the cause of over one half of all skin and soft tissue infections seen in many hospitals and emergency departments. The risk factors for infection with this pathogen differ from those associated with hospital-acquired strains. Mild to moderate infections can generally be treated with oral antibiotics, while more serious infections may require parenteral therapy. Sulfamethoxazole/trimethoprim and clindamycin are the preferred oral agents due to their efficacy, tolerability, well established side effect profiles, and cost. Vancomycin is the standard of care for parenteral therapy, although clindamycin is an acceptable parenteral alternative. More costly agents such as linezolid, daptomycin, and quinupristin/dalfopristin should be reserved for patients with severe infections, multiple allergies, or in strains with unusual resistance patterns. The best way to prevent and control outbreaks is to maintain standard infection control procedures including excellent hand hygiene.

CONCLUSIONS

CA-MRSA is a serious and frequently seen pathogen. Proper antibiotic selection that takes into account patient factors, disease severity, ease of administration, and cost is necessary to maximize favorable patient outcomes.

A pilot study of high-dose short duration daptomycin for the treatment of patients with complicated skin and skin structure infections caused by gram-positive bacteria

BACKGROUND

Methicillin-susceptible and -resistant (MRSA) Staphylococcus aureus are significant causes of complicated skin and skin structure infections (cSSSI). The bactericidal antibiotic daptomycin is approved for gram-positive cSSSI at 4 mg/kg/day for 7-14 days, but the optimal dose level and duration of therapy have not been firmly established. This pilot study evaluated the efficacy and safety of daptomycin at 10 mg/kg every 24 h for 4 days [high-dose short duration (HDSD) regimen] vs. standard of care therapy with vancomycin or semi-synthetic penicillin for the treatment of cSSSI.

METHODS

This was a semi-single blind, randomised, multicentre, comparative trial. The primary efficacy end-point was the clinical response 7-14 days posttherapy.

RESULTS

One hundred patients were randomised; 48 in each arm were treated. The treatment groups were well balanced with respect to demographics, comorbidities and the type of infection (75% because of MRSA). Overall, clinical success rates were 75.0% (36/48) for daptomycin and 87.5% (42/48) for comparator (95% confidence interval for the difference: -27.9, 2.9). The median duration of comparator therapy was 8 days. Two comparator patients and no daptomycin patients experienced treatment-related serious adverse events requiring hospitalisation.

CONCLUSION

We found that the HDSD regimen had a safety profile similar to that seen in previous studies. Although the differences were not statistically significant, clinical success rates for comparator were higher than for daptomycin. In post hoc analyses HDSD daptomycin performed better in some subgroups (e.g. outpatients) than in others (e.g. certain MRSA infections). These observations require confirmation in larger trials.

The incidence of and risk factors for MRSA bacteraemia in an HIV-infected cohort in the HAART era

OBJECTIVES

To define the incidence and risk factors for methicillin resistant Staphylococcus aureus (MRSA) bacteraemia in an HIV-infected population.

METHODS

From January 1, 2000 to December 31, 2004, we conducted a retrospective cohort study. We identified all cases of Staphylococcus aureus bacteraemia (SAB), including MRSA, among patients enrolled in the Johns Hopkins Hospital out-patient HIV clinic. A conditional logistic regression model was used to identify risk factors for MRSA bacteraemia compared with methicillin-sensitive SAB and no bacteraemia in unmatched (1:1) and matched (1:4) nested case-control analyses, respectively.

RESULTS

Of 4607 patients followed for a total of 11 020 person-years (PY) of follow-up, 216 episodes of SAB occurred (incidence: 19.6 cases per 1000 PY), including 94 cases (43.5%) which were methicillin-resistant. The incidence of MRSA bacteraemia increased from 5.3 per 1000 PY in 2000-2001 to 11.9 per 1000 PY in 2003-2004 (P=0.001). Multivariate analysis demonstrated that independent predictors of MRSA bacteraemia (vs. no bacteraemia) were injection drug use (IDU), end-stage renal disease (ESRD) and CD4 count <200 cells/microL.

CONCLUSIONS

MRSA bacteraemia was an increasingly common diagnosis in our HIV-infected cohort, especially in patients with history of IDU, low CD4 cell count and ESRD.

Optimal imaging strategy for community-acquired Staphylococcus aureus musculoskeletal infections in children

BACKGROUND

Invasive musculoskeletal infections from community-acquired methicillin-resistant and methicillin-susceptible Staphylococcus aureus (CA-SA) are increasingly encountered in children. Imaging is frequently requested in these children for diagnosis and planning of therapeutic interventions.

OBJECTIVE

To appraise the diagnostic efficacy of imaging practices performed for CA-SA osteomyelitis and its complications.

MATERIALS AND METHODS

A retrospective review was conducted of the clinical charts and imaging studies of CA-SA osteomyelitis cases since 2001 at a large children's hospital.

RESULTS

Of 199 children diagnosed with CA-SA osteomyelitis, 160 underwent MRI examination and 35 underwent bone scintigraphy. The sensitivity of MRI and bone scintigraphy for CA-SA osteomyelitis was 98% and 53%, respectively. In all discordant cases, MRI was correct compared to bone scintigraphy. Extraosseous complications of CA-SA osteomyelitis detected only by MRI included subperiosteal abscesses (n = 77), pyomyositis (n = 43), septic arthritis (n = 31), and deep venous thrombosis (n = 12).

CONCLUSION

MRI is the preferred imaging modality for the investigation of pediatric CA-SA musculoskeletal infection because it offers superior sensitivity for osteomyelitis compared to bone scintigraphy and detects extraosseous complications that occur in a substantial proportion of patients.

Skin and soft-tissue infections caused by community-acquired methicillin-resistant Staphylococcus aureus

Community-acquired methicillin-resistant Staphylococcus aureus (MRSA) infection has become epidemic. Skin and soft-tissue infections (SSTIs) are the most frequent forms of the disease. Obtainment of culture specimens is important for documentation of the presence of MRSA and for susceptibility testing to guide therapy. Purulent lesions should be drained whenever possible. In areas where community-acquired MRSA isolates are prevalent, uncomplicated SSTI in healthy individuals may be treated empirically with clindamycin, trimethoprim-sulfamethoxazole, or long-acting tetracyclines, although specific data supporting the efficacy of these treatments are lacking. In healthy patients with small purulent lesions, drainage alone may be sufficient. In patients with complicated SSTI requiring hospitalization or intravenous therapy, vancomycin is the drug of choice because of the low cost, efficacy, and safety. Linezolid, daptomycin, and tigecycline are also effective, although published studies on the last 2 agents for the treatment of SSTI due to MRSA are more limited. Dalbavancin, telavancin, and ceftobiprole are investigational agents that may expand our therapeutic options for the treatment of SSTI caused by MRSA.

Community-associated methicillin-resistant Staphylococcus aureus

Community-associated methicillin-resistant Staphylococcus aureus (CA-MRSA) has emerged over the last decade across the United States and the world, becoming a major pathogen in many types of community-acquired infections. Although most commonly associated with minor skin and soft tissue infections, such as furuncles, CA-MRSA also can cause necrotizing fasciitis, pyomyositis, osteoarticular infections, and community-acquired pneumonia. This article discusses the epidemiology, diagnosis, and management of these infections from the perspective of the emergency physician.

Methicillin-resistant Staphylococcus aureus--positive surgical site infections in face-lift surgery

OBJECTIVES

To determine the incidence of methicillin-resistant Staphylococcus aureus (MRSA)-positive surgical site infections after face-lift surgery and to discuss the screening, prevention, and treatment of such infections.

METHODS

The patient charts of 780 patients who underwent a deep-plane rhytidectomy between 2001 and 2007 were reviewed for postoperative wound infections. Culture results and sensitivities were recorded. To our knowledge, this is the first study that documents MRSA-positive surgical site infections after face-lift surgery.

RESULTS

Five of 780 patients (0.6%) who underwent face-lift surgery by the senior surgeon had postoperative surgical site infections. Four of the 5 patients had cultures that were positive for MRSA. Two of these patients (0.3%) required hospitalization and had collections that had to be opened or drained and developed wound breakdown. Both patients eventually responded to wound care along with intravenous and then oral antibiotic therapy. The other 2 MRSA-infected patients responded to oral antibiotic therapy and local wound care alone. The 2 complicated infections occurred on postoperative days 5 and 8. These 2 patients were the only ones among the 5 patients with positive cultures who had known recent contact with another physician or a hospital. All infections occurred in the year 2006, with 3 patients experiencing infection in the last 4 months of the year. Herein, we describe the incidence and sequelae of MRSA infections and colonization. The 2 major different subsets of MRSA are community-acquired MRSA and health care-associated MRSA. Surgical site infections that are positive for MRSA blur this division, which affects many aspects of the course of disease and treatment. We also discuss strategies for screening, preventing, and treating MRSA surgical site infections.

CONCLUSIONS

Methicillin-resistant S aureus-positive surgical site infection is an increasingly problematic issue in all surgical fields. In the future, MRSA-positive infections will be more prevalent and will require well-developed screening, prevention, and treatment strategies.

Predicting observation unit treatment failures in patients with skin and soft tissue infections

Background

Skin and soft tissue infections are a common admission diagnosis to emergency department (ED) observation units (OU). Little is known about which patients fail OU treatment.

Aims

This study evaluates clinical factors of skin or soft tissue infections associated with further inpatient treatment after OU treatment failure.

Methods

A structured retrospective cohort study of consecutive adults treated for abscess or cellulitis in our OU from April 2005 to February 2006 was performed. Records were identified using ICD-9 codes and were abstracted by two trained abstractors using a structured data collection form. Significant variables on univariate analysis P < 0.1 were entered into a multivariate logistic regression.

Results

A total of 183 patient charts were reviewed. Four patients with a non-infectious diagnosis were excluded, leaving 179 patients. The median age was 41 (interquartile range: 20–74). Following observation treatment, 38% of patients required admission. The following variables were evaluated for association with failure to discharge home: intravenous drug use, gender, a positive community-acquired methicillin-resistant Staphylococcus aureus culture, age, presence of medical insurance, drainage of an abscess in the ED, diabetes and a white blood cell count (WBC) greater than 15,000. Following multivariate analysis only female gender odds ratio (OR) 2.33 [95% confidence interval (CI): 1.06–5.15] and WBC greater than 15,000 OR 4.06 (95% CI: 1.53–10.74) were significantly associated with failure to discharge.

Conclusions

Among OU patients treated for skin and soft tissue infections, women were twice as likely to require hospitalization and patients with a WBC > 15,000 on presentation to the ED, regardless of gender, were 4 times more likely to require hospitalization.

The benefit of empiric treatment for methicillin-resistant Staphylococcus aureus

Community-acquired methicillin-resistant Staphylococcus aureus (CA-MRSA) has emerged as a major pathogen causing skin and soft tissue infections (SSTI). It is unclear whether treatment with antibiotics active in vitro against CA-MRSA improves patient outcomes. At our institution, where there is a high rate of CA-MRSA SSTI, we have adopted an empiric treatment algorithm that promotes both the use of antibiotics likely active against CA-MRSA and early incision and drainage of abscesses. The objective of this research was to study the effectiveness of an empiric treatment algorithm for SSTI directed against CA-MRSA. The study was a retrospective chart review. Treatment was categorized as either conforming or not conforming to the algorithm. Outcomes were categorized as worsening of infection or improvement, according to predefined criteria. There were 50 consecutive Emergency Department patients treated as outpatients for MRSA SSTI. Treatment conformed to the algorithm in 29 of 50 cases. Clinical failure occurred in 3% of cases treated according to the algorithm, compared with 62% of those not treated according to the algorithm (p < 0.001). Among 37 cases that underwent immediate incision and drainage, initial treatment with antibiotics active in vitro against the MRSA isolate was associated with a decreased clinical failure rate when compared to those treated with inactive antibiotics (0% vs. 67%, p < 0.001). Empiric treatment of CA-MRSA SSTI according to an algorithm that promotes use of antibiotics active in vitro against CA-MRSA is associated with improved clinical outcomes.

Efficacy of oral beta-lactam versus non-beta-lactam treatment of uncomplicated cellulitis

BACKGROUND

Preferred therapy for purulent skin and soft tissue infections is incision and drainage, but many infections cannot be drained. Empiric therapies for these infections are ill-defined in the era of community-acquired methicillin-resistant Staphylococcus aureus.

METHODS

A multicenter retrospective cohort study of outpatients treated for cellulitis was conducted to compare clinical failure rates of oral beta-lactam and non-beta-lactam treatments. Exclusion criteria included purulent infection requiring incision and drainage, complicated skin and soft tissue infection, chronic ulceration, and intravenous antibiotics. Failure rates were compared using logistic regression to adjust for both covariates associated with failure and a propensity score for beta-lactam treatment.

RESULTS

Of 2977 patients, 861 met inclusion criteria and were classified by treatment: beta-lactam (n = 631) or non-beta-lactam therapy (n = 230). Failure rates were 14.7% versus 17.0% (odds ratio [OR] 0.85, 95% confidence interval [CI], 0.56-1.31) for beta-lactam and non-beta-lactam therapy, respectively. Failure was associated with: age (P = .02), acute symptom severity (P = .03), animal bites (P = .03), Charlson score > 3 (P = .02), and histamine-2 receptor antagonist use (P = .09). Relative efficacy of beta-lactam therapy was greater after adjustment for factors associated with failure but remained statistically insignificant (adjusted OR 0.81, 95% CI, 0.53-1.24); adjusted including propensity score covariate (OR 0.71, 95% CI, 0.45-1.13). Discontinuation due to adverse effects differed between beta-lactam (0.5%) and non-beta-lactam (2.2%) therapies (P = .04).

CONCLUSION

There was no significant difference in clinical failure between beta-lactam and non-beta-lactam antibiotics for the treatment of uncomplicated cellulitis. Increased discontinuation due to adverse events with non-beta-lactam therapy was observed.

The skin in the gym: a comprehensive review of the cutaneous manifestations of community-acquired methicillin-resistant Staphylococcus aureus infection in athletes

Community-acquired methicillin-resistant Staphylococcus aureus (CAMRSA) infection is currently a problem of epidemic proportion. Athletes represent a specific group of individuals who are at increased risk to develop CAMRSA skin infections. In this article, the previously published reports of cutaneous CAMRSA infections in athletes are categorized by sport and summarized. General treatment guidelines for the management of cutaneous CAMRSA infection and its associated lesions in athletes are discussed. Also, recommendations for the prevention of CAMRSA skin infection in sports participants are reviewed.

Guidelines for UK practice for the diagnosis and management of methicillin-resistant Staphylococcus aureus (MRSA) infections presenting in the community

These guidelines have been developed by a Working Party convened on behalf of the British Society for Antimicrobial Chemotherapy. Their aim is to provide general practitioners and other community- and hospital-based healthcare professionals with pragmatic advice about when to suspect MRSA infection in the community, when and what cultures should be performed and what should be the management options, including the need for hospitalization.

Emergency department management of community-acquired methicillin-resistant Staphylococcus aureus

Staphylococcus aureus is a known cause of a variety of illnesses that present to the emergency department, including skin and soft tissue infections, pneumonia, and sepsis. Managing these conditions has become more difficult with the emergence of bacterial strains in the community that are resistant to traditional first-line antibiotics. Emergency care providers need to be aware of the increased prevalence of these resistant bacteria, to understand the characteristics of the infections with which they are associated, and to know the effective antibiotic options for treating these bacterial infections in the emergency department patient population.

Community-acquired methicillin-resistant Staphylococcus aureus: an emerging pathogen in orthopaedics

Staphylococcus aureus (S aureus) remains one of the most common pathogens for skin and soft-tissue infections encountered by the orthopaedic surgeon. Community-acquired methicillin-resistant S aureus (CA-MRSA) has become increasingly prevalent, particularly among athletes, children in day care, homeless persons, intravenous drug users, men who have sex with men, military recruits, certain minorities (ie, Alaskan Natives, Native Americans, Pacific Islanders), and prison inmates. Risk factors include antibiotic use within the preceding year, crowded living conditions, compromised skin integrity, contaminated surfaces, frequent skin-to-skin contact, shared items, and suboptimal cleanliness. When a patient presents with a skin or soft-tissue infection, the clinician should determine whether an abscess or other infection needs to be surgically incised and drained. Cultures should be performed. When the patient is a member of an at-risk group or has any of the risk factors for CA-MRSA, beta-lactam antibiotics (eg, methicillin) are no longer a reasonable choice for treatment. Empiric treatment should consist of non-beta-lactam antibiotics active against CA-MRSA.

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.

Antimicrobial-resistant pathogens: an emerging pediatric threat

The clinical impact of these three bacterial threats is readily apparent to any who practice pediatrics. The potential virulence of CA-MRSA and MDR pneumococci and the threat of failed antimicrobial options for MDRGN pose enormous challenges now and in the near future. With careful attention to antimicrobial stewardship, however, and knowledge of the clinical and epidemiologic factors of these organisms, one can hope to mitigate the impact on patient care and outcomes while awaiting ongoing discovery of new antimicrobial options. Most important, however, will be careful and thoughtful management of any new antimicrobial products to protect their efficacy for the future.

Methicillin-resistant Staphylococcus aureus infections among healthy full-term newborns

OBJECTIVE

Methicillin-resistant Staphylococcus aureus (MRSA) strains have emerged in the community, causing disease among healthy people lacking traditional risk factors for MRSA infection. This article describes an outbreak of MRSA among healthy full-term newborns.

DESIGN

Cases were identified and corresponding medical information collected. Telephone interviews were conducted with mothers of cases and surveillance cultures from mothers and newborns were performed. MRSA isolates were genotyped.

SETTING

Hospital in Chicago, Illinois, USA.

PARTICIPANTS

Newborns, their mothers and hospital healthcare workers.

INTERVENTION

Nursery infection control practices were enhanced. The MRSA-colonised healthcare workers received intranasal mupirocin.

MAIN OUTCOME

Within 4-23 days of birth, 11 newborns were identified with pustules, vesicles or blisters located on the head, groin, perineum, ears, legs, chin and trunk. All received antimicrobials and recovered without incident.

RESULTS

None of 432 peripartum women, one of 399 newborns, and two of 135 healthcare workers were nasal MRSA carriers. Available isolates from six patients, two healthcare workers, and one from an MRSA-colonised newborn were similar by pulsed-field gel electrophoresis. Other than contact with the hospital, no common exposures of MRSA transmission were identified.

CONCLUSIONS

MRSA strains that initially emerged in the community are now causing disease in healthcare settings. Providers should be aware that MRSA can cause skin infections among healthy newborns. Adherence to standard infection control practices is important to prevent transmission of MRSA in nurseries.

A review of community-associated methicillin-resistant Staphylococcus aureus skin and soft tissue infections

Methicillin-resistant Staphylococcus aureus (MRSA) has emerged as a cause of infection among otherwise healthy children and adults in the community. Skin and soft tissue infections are most common, but invasive manifestations also occur. A limited number of strains that may possess unique virulence or transmissibility factors have accounted for the majority of these infections. These strains emerged in the community but now are being transmitted in both community and healthcare settings. Incision and drainage remains the primary treatment for skin abscesses. Strains of MRSA circulating in the community generally are susceptible to a number of nonbeta-lactam antimicrobial agents, although resistance patterns may vary temporally and geographically. Educating patients on strategies to prevent further transmission is a critical component of case management. More data are needed to determine optimal strategies for management and prevention of MRSA skin infections in the community.

Genotypic characteristics of Staphylococcus aureus isolates from a multinational trial of complicated skin and skin structure infections

The impact of bacterial genetic characteristics on the outcome of patients with Staphylococcus aureus infections is uncertain. This investigation evaluated potential associations between bacterial genotype and clinical outcome using isolates collected as part of an international phase 2 clinical trial (FAST II) evaluating telavancin for the treatment of complicated skin and skin structure infections (cSSSI). Ninety S. aureus isolates from microbiologically evaluable patients with cSSSI enrolled in the FAST II trial from 11 sites in the United States (56 isolates, or 62%) and 7 sites in South Africa (34 isolates, or 38%) were examined for staphylococcal cassette chromosome mec, agr, and the presence of 31 virulence genes and subjected to pulsed-field gel electrophoresis (PFGE). South African methicillin-susceptible S. aureus (MSSA) isolates were more likely to carry certain virulence genes, including sdrD (P = 0.01), sea (P < 0.01), and pvl (P = 0.01). All 44 (49%) methicillin-resistant S. aureus (MRSA) isolates were from the United States; 37 (84%) were strain USA 300 by PFGE. In the United States, MRSA isolates were more likely than MSSA isolates to carry genes for sdrC (P = 0.03), map/eap (P = 0.05), fnbB (P = 0.11), tst (P = 0.02), sea (P = 0.04), sed (P = 0.04), seg (P = 0.11), sej (P = 0.11), agr (P = 0.09), V8 (P = 0.06), sdrD, sdrE, eta, etb, and see (P < 0.01 for all). MRSA isolates were more often clonal than MSSA isolates by PFGE. Isolates from patients who were cured were significantly more likely to contain the pvl gene than isolates from patients that failed or had indeterminate outcomes (79/84 [94%] versus 3/6 [50%]; P = 0.01). S. aureus strains from different geographic regions have different distributions of virulence genes.

Trends in prescribing beta-lactam antibiotics for treatment of community-associated methicillin-resistant Staphylococcus aureus infections

Rates of prescribing of beta-lactam antibiotics as initial empirical therapy for patients with skin and soft tissue infections (SSTIs) caused by molecularly and epidemiologically characterized community-associated methicillin-resistant Staphylococcus aureus (CA-MRSA) isolates were assessed over a 3-year period. A prospectively developed database was used to calculate the prevalence of CA-MRSA SSTIs from 2004 to 2006. Molecular characterization of the MRSA isolate and medical record review for assessment of initial antimicrobial therapy were performed on a subset of patients. Among 2,636 patients with S. aureus SSTIs, the prevalence of CA-MRSA was 9% in 2004, 16% in 2005, and 21% in 2006 (P < 0.0001, chi-square test for trend). Seventy-five percent of CA-MRSA isolates tested were of the USA 300 or 400 clone type. Ninety-two percent of CA-MRSA isolates tested were positive for Panton-Valentine leukocidin, of which 90% carried staphylococcal chromosomal cassette mec type IV. The rate of use of a beta-lactam antibiotic as initial empirical therapy for patients with CA-MRSA SSTIs was 86%, 77%, and 60% in 2004, 2005, and 2006, respectively (P = 0.04, chi-square test for trend). Thirty percent of beta-lactam-treated patients had a documented risk factor for CA-MRSA infection. The use of a beta-lactam antibiotic as initial empirical therapy for CA-MRSA SSTIs has decreased significantly over the past 3 years. However, even as the prevalence of CA-MRSA SSTIs approaches 25%, the majority of patients are still receiving inactive antimicrobial therapy. Further evaluation of the outcomes associated with discordant therapy for CA-MRSA SSTIs is needed.

Community-associated methicillin-resistant Staphylococcus aureus: Incidence, clinical presentation, and treatment decisions

Community-associated methicillin-resistant Staphylococcus aureus (CA-MRSA) infections have been reported with increasing frequency from many parts of the world. Most infections involve the skin and soft tissue structures, and CA-MRSA is now the most commonly identifiable cause of purulent skin and soft tissue infections. The spectrum of disease can range from simple cutaneous abscesses to fulminant necrotizing infection. CA-MRSA strains, in contrast to healthcare-associated strains, are generally extra virulent and produce more toxins. Unlike the healthcare-associated strains, they demonstrate variable susceptibility patterns to various classes of antibiotics. Empiric antibiotic therapy for patients with purulent skin and soft tissue infection and for those presenting with severe, life-threatening infections should include an agent active against CA-MRSA.

Treatment of community-associated methicillin-resistant Staphylococcus aureus

Methicillin-resistant Staphylococcus aureus has emerged in the community among patient populations without traditional antibiotic resistance risk factors and is causing a variety of clinical syndromes, in particular skin and soft tissue infections. These infections can range from minor skin involvement that can be treated in an outpatient setting to more serious infections such as necrotizing fasciitis requiring hospitalization. Inpatient and outpatient healthcare providers must be aware of the treatment, prevention, and infection control practices for this emerging pathogen.

Randomized, double-blind, placebo-controlled trial of cephalexin for treatment of uncomplicated skin abscesses in a population at risk for community-acquired methicillin-resistant Staphylococcus aureus infection

Empirical use of beta-lactam antibiotics, the preferred agents for treating uncomplicated skin and soft tissue infections, may no longer be appropriate for these infections because of the increasing prevalence of community strains of methicillin-resistant Staphylococcus aureus (MRSA). Retrospective studies, however, suggest that outcomes are good even when beta-lactams are used. We conducted a randomized, double-blind trial of 166 outpatient subjects comparing placebo to cephalexin at 500 mg orally four times for 7 days after incision and drainage of skin and soft tissue abscesses. The primary outcome was clinical cure or failure 7 days after incision and drainage. S. aureus was isolated from 70.4% of abscess cultures. Of the isolates tested 87.8% were MRSA, 93% of which were positive for Panton-Valentine leucocidin genes. Clinical cure rates were 90.5% (95% confidence interval, 0.82 to 0.96) in the 84 placebo recipients and 84.1% (95% confidence interval, 0.74 to 0.91) in the 82 cephalexin recipients (difference in the two proportions, 0.0006; 95% confidence interval, -0.0461 to 0.0472; P = 0.25). The 90.5% cure rate observed in the placebo arm and 84.1% cure rate observed in the cephalexin arm provide strong evidence that antibiotics may be unnecessary after surgical drainage of uncomplicated skin and soft tissue abscesses caused by community strains of MRSA.