Outpatient Management of Community-associated Methicillin-resistant Staphylococcus aureus Skin and Soft Tissue Infection

During the past decade, there has been a dramatic increase in the number of patients presenting with skin and soft tissue infections in the outpatient setting. The predominant causative bacterium for these infections has recently been identified as community-associated methicillin-resistant Staphylococcus aureus (CA-MRSA). It is estimated that nearly 80% of infections caused by CA-MRSA manifest as skin and soft tissue infections which are of mild to modest severity. However, invasive disease and fatal illness has been reported among otherwise healthy adults and children. The rapid evolution of CA-MRSA presents a unique challenge for pediatric health care providers. As such, it is critical to raise awareness regarding the epidemiology, microbiology, and evidence-based treatment options for treating skin and soft tissue infections in the age of CA-MRSA. The aims of this article include discussion regarding the epidemiology, microbiology, and evidence-based management of CA-MRSA as well as publication of a more relevant one-page evidence-based treatment flow diagram and antimicrobial prescribing table for health care providers practicing in the ambulatory care setting.     

Preventing unintentional injuries in Indigenous children and youth in Canada

Unintentional injuries are the leading cause of death in Canadian Indigenous children and youth, occurring at rates three to four times the national average. Death and disabling injuries not only devastate families and communities but take a heavy toll on health care resources. The lack of statistics, ongoing surveillance or injury prevention programs for Indigenous children and adolescents further compound human and health care costs. Indigenous communities are heterogeneous culturally, in terms of access to resources, and even as to risks and patterns of injury. Yet in general, they are far more likely to be poor, to have substandard housing and to have difficulty accessing health care, factors which increase the risk and impact of injury. There are urgent needs for injury surveillance, research, capacity-building, knowledge dissemination, as well as for injury prevention programs that focus on Indigenous populations. Effective injury prevention would involve multidisciplinary, collaborative and sustainable approaches based on best practices while being culturally and linguistically specific and sensitive.     

万古霉素在儿童社区获得性耐甲氧西林金黄色葡萄球菌肺炎的个体化抗感染治疗策略

社区获得性耐甲氧西林金黄色葡萄球菌(CAMRSA)肺炎患病率报道增多。CA-MRSA菌株基因突变、MIC漂移、抗菌药物耐药性增加等因素使儿科医师在经验性治疗CA-MRSA肺炎时面临重大挑战。万古霉素是抗MRSA感染的一线抗菌药物,具有治疗窗窄及肾脏毒性等特点。患儿在不同病理生理状态下,以药代动力学与药效学(PK/PD)原理及治疗药物浓度监测(TDM)为指导,进行万古霉素个体化治疗,可提高CA-MRSA肺炎患儿使用万古霉素的安全性和有效性,并减少耐药菌株产生。     

Daptomicina a dosis altas en infección diseminada por Staphylococcus aureus resistente a meticilina

Community-acquired methicillin-resistant Staphylococcus aureus (CA-MRSA) infections are an increasing problem in our country. Daptomycin is a bactericidal antibiotic with activity against CA-MRSA. Experience using high-dose daptomycin is reviewed in three paediatric patients with severe-disseminated CA-MRSA infection with a favourable microbiological and clinical response.     

Prospective comparison of risk factors and demographic and clinical characteristics of community-acquired,methicillin-resistant versus methicillin-susceptible Staphylococcus aureus infection in children

CONTEXT: Community-acquired, methicillin-resistant (CA-MRSA) infections in children are increasing in frequency for unknown reasons. OBJECTIVES: To compare the presence of risk factors for methicillin resistance between patients with CA-MRSA and community-acquired methicillin-susceptible (CA-MSSA) infection and to compare the presence of risk factors among household contacts of the patients from both groups. To compare the demographic and clinical characteristics between children with CA-MRSA and CA-MSSA infection. DESIGN: Prospective observational study conducted between February 2, 2000 and November 14, 2000, excluding the month of May and the period between September 2 and October 15. SETTING AND PATIENTS: Texas Children's Hospital, Houston, TX; inpatients and outpatients with community-acquired infection. MAIN OUTCOME MEASURES: Proportion of MRSA among all community-acquired infections. The presence of risk factors associated with methicillin resistance among patients, and their household contacts, with CA-MRSA and CA-MSSA. RESULTS: The monthly rates of methicillin resistance of varied between 35 and 51%. CA-MSSA isolates were associated with deep-seated infections significantly more often (30%) than CA-MRSA isolates (11%; P= 0.01). CA-MRSA isolates were generally susceptible to clindamycin and trimethoprim-sulfamethoxazole and resistant to erythromycin. There were no significant differences in the exposure to risk factors between children with CA-MRSA and CA-MSSA infection. No significant risk factors for CA-MRSA were identified among household contacts. CONCLUSIONS: MRSA is an established, community-acquired pathogen in our area. This necessitates a change in empiric therapy of infections suspected to be caused by.     

Health research involving First Nations,Inuit and Métis children and their communities

Canadian and international guidelines address the ethical conduct of health research in general and the issues affecting Indigenous populations in particular. This statement summarizes, for clinicians and researchers, relevant ethical and practical considerations for health research involving Aboriginal children and youth. While not intended to duplicate findings arising from lengthy collaborative processes, it does highlight ‘wise practices’ that have successfully generated knowledge relevant to, respectful of and useful for Aboriginal children, youth and their communities. Further research on current health issues and inequities should lead to practical, effective and culturally relevant applications. Expanding our knowledge of ways to address the health disparities facing Canada’s Aboriginal children and youth can inform health policy and the provision of services. Community-based participatory research is proposed as a means to achieve this goal.     

Community-genotype strains of methicillin-resistant Staphylococcus aureus with high-level mupirocin resistance in a neonatal intensive care unit

Aim

The aim of this study was to investigate the genotypes of mupirocin-resistant methicillin-resistant Staphylococcus aureus (MR-MRSA) isolates in our neonatal intensive care unit (NICU) and their potential source.

Study design

One hundred one MRSA isolates obtained from 59 inborn and 42 outborn infants were identified and their antimicrobial susceptibility determined. Using pulse-field gel electrophoresis (PFGE) analysis, MR-MRSA isolates obtained from the neonatal patients in the NICU were compared with those from adult hospitalized in the same hospital and with community-associated MRSA (CA-MRSA) isolates recovered from different hospitals in Korea.

Results

Overall, 47% of CA-MRSA and 79% of healthcare-associated MRSA isolates exhibited high-level mupirocin resistance (HLMR). Forty-five percent of the outborn infants were considered to have CA-MRSA at the time of admission to our NICU. Most HLMR-MRSA isolates from neonates were grouped into a single cluster by PFGE analysis, and which included CA-MRSA isolates with HLMR recovered from outborn infants who were already colonized when they were transferred to our NICU. They belonged to the same PFGE group as the community-genotype strains isolated from different hospitals in Korea. HLMR-MRSA isolates from adults patients were classified as different clones. None of the attending staff in the NICU were nasal carriers.

Conclusion

Community-genotype strains of MRSA with HLMR may be imported to our NICU through obstetrics clinics and contribute to MRSA colonization or infection in facilities with a high rate of admission of outborn infants.     

Pulmonary infections and community associated methicillin resistant Staphylococcus aureus: a dangerous mix?

The incidence of complicated pneumonias in children is increasing with a concurrent increase in the incidence of community-associated methicillin-resistant Staphylococcus aureus (CA-MRSA) infections. CA-MRSA is distinct from hospital associated MRSA [HA-MRSA] in regards to its genotype, epidemiology, and clinical course. Unlike HA-MRSA, CA-MRSA often strikes young, previously healthy children. Pneumonias caused by CA-MRSA have a rather distinct presentation. Because of its pore-forming toxins, namely Panton-Valentine leukocidin (PVL) and alpha-hemolysin, extensive necrotizing disease with corresponding hypoxaemia and hypercarbia is common. Other features include multilobar disease, leucopenia, haemoptysis, and high mortality rates. A previous influenza-like illness or skin and soft tissue infection [SSTI] often precede the development of pneumonia due to CA-MRSA. Vancomycin is recommended as first-line empiric therapy for suspected CA-MRSA infections. However, vancomycin is not an ideal agent for the treatment of pneumonia given its poor concentrating ability in alveolar fluid. Linezolid and clindamycin have also been used in the treatment of CA-MRSA pneumonia and ongoing research is looking for alternative antimicrobials. Recent studies have continued to report a lack of correlation between nasal colonization and active infections due to CA-MRSA. Given that the role of nasal colonization in CA-MRSA infection is not clear, the utility of decolonization treatment has been a point of debate. Finally, patients with cystic fibrosis are becoming increasingly colonized with MRSA as opposed to MSSA. There is some accumulating evidence that patients with MRSA show a more rapid deterioration in their degree of obstructive disease as measured by forced expiratory volume in one second (FEV₁). However, it still is not clear whether MRSA is a marker for worsening disease or whether it actually is a cause of disease progression in cystic fibrosis. More longitudinal data is needed to understand how MRSA colonization impacts the course of disease in cystic fibrosis.     

Comparison of community-acquired methicillin-resistant <Emphasis Type="Italic">Staphylococcus</Emphasis><Emphasis Type="Italic">aureus</Emphasis> 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.     

Fascitis necrosante por Staphylococcus aureus resistente a la meticilina adquirido en la comunidad productor de leucocidina de Panton-Valentine

Community-Acquired Methicillin-Resistant Staphylococcus aureus (CA-MRSA) is a worldwide emerging pathogen that is able to produce serious skin and soft- tissue infections such as necrotizing fasciitis, as well as pneumonia and osteomyelitis. We present a 14 month child with necrotizing fasciitis, confirmed by magnetic resonance imaging, produced by CA-MRSA Panton-Valentine leukocidin producer. The clinical outcome was good after early surgical treatment and the administration of intravenous clindamycin for two weeks. We review microbiological aspects and treatment guidelines of these infections.     

Clinical and molecular epidemiology of community-acquired methicillin-resistant Staphylococcus aureus infections among children with risk factors for health care-associated infection: 2001-2003

BACKGROUND: Methicillin-resistant Staphylococcus aureus (MRSA) has recently emerged as a common cause of infection in children in many parts of the world. The epidemiology of community-acquired MRSA (CA-MRSA) among healthy children has been recently described. However, little is known about CA-MRSA in children with underlying medical conditions. OBJECTIVE: To compare the clinical and molecular epidemiology of CA-MRSA in children with and without risk factors for health care-associated infections (RF-HAI). METHODS: We conducted a 3-year retrospective cohort study of children with CA-MRSA infection. RF-HAI, including hospitalization within the past year, indwelling medical devices or chronic medical condition, were identified by chart review. Genetic relatedness of CA-MRSA strains was assessed by pulsed field gel electrophoresis. Polymerase chain reaction was used to detect Panton-Valentine leukocidin and determine staphylococcal chromosomal cassette carrying the mecA methicillin-resistant gene (SCCmec) type. RESULTS: We identified 446 episodes of community-acquired S. aureus infections, of which 134 (30%) were caused by MRSA. During the 3-year study period, the proportion of S. aureus infections caused by MRSA rose from 15% (12 of 80) to 40% (93 of 235) (P < 0.001) with the increase noted predominately in children with skin and soft tissue infections. RF-HAI were identified in 56 (42%) patients with CA-MRSA. Among subjects with CA-MRSA, children with RF-HAI were more likely to have had an invasive infection than healthy children (32% versus 5%; P < 0.001). CA-MRSA isolates from children with RF-HAI were similar to those without RF-HAI; all laboratory-retained CA-MRSA isolates harbored the SCCmec type IV cassette, and almost all isolates were susceptible to trimethoprim-sulfamethoxazole and clindamycin. However, pulsed field gel electrophoresis revealed greater molecular diversity among CA-MRSA isolates recovered from children with RF-HAI compared with those from otherwise healthy children (P = 0.001). Additionally CA-MRSA isolates from children with RF-HAI were less likely to contain sequences for Panton-Valentine leukocidin (P < 0.001) and more likely to be resistant to 3 or more classes of antibiotics (P = 0.033). CONCLUSION: CA-MRSA strains recovered from children with RF-HAI were phenotypically similar to those recovered from healthy children The absence of SCCmec type II or III MRSA among children with RF-HAI suggests that CA-MRSA strains might have become endemic within pediatric health care facilities.     

Staphylococcus aureus bloodstream infections in children: A population-based assessment

BACKGROUND:

Although Staphylococcus aureus is a major cause of bloodstream infections, population-based data on these infections in children are limited.

OBJECTIVE:

To describe the epidemiology of S aureus bacteremia in children.

METHODS:

Population-based surveillance for all incident S aureus bacteremias was conducted among children (18 years of age or younger) living in the Calgary Health Region (Alberta) from 2000 to 2006.

RESULTS:

During the seven-year study, 120 S aureus bloodstream infections occurred among 119 patients; 27% were nosocomial, 18% health care associated and 56% community acquired. The annual incidence was 6.5/100,000 population and 0.094/1000 live births. A total of 52% had a significant underlying condition, and this was higher for nosocomial cases. Bone and joint (40%), bacteremia without a focus (33%), and skin and soft tissue infections (15%) were the most common clinical syndromes. Infections due to methicillin-resistant S aureus were uncommon (occurring in one infection) and three patients (2.5%) died.

CONCLUSIONS:

S aureus bacteremia is an important cause of morbidity in the paediatric age group. Underlying medical conditions and implanted devices are important risk factors. Methicillin-resistant S aureus and mortality rates are low.     

Panton-Valentine leukocidin in the pathogenesis of community-associated methicillin-resistant Staphylococcus aureus infection

Methicillin-resistant Staphylococcus aureus (MRSA) is an important human pathogen that causes serious infectious diseases and was endemic in hospitals by the late 1960s. Beginning with its first report in the late 1990s, the rapid emergence of community-associated MRSA (CA-MRSA) worldwide responsible for a wide spectrum of diseases ranging from minor skin infections to fatal necrotizing pneumonia has been found in previously healthy individuals without established risk factors for MRSA acquisition. Recently, various virulence determinants unique to CA-MRSA have been uncovered, which explain how the pathogen spreads easily and causes severe CA-MRSA infections among humans. However, the role of Panton-Valentine leukocidin (PVL) in the pathogenesis of CA-MRSA infection is currently a matter of much debate because of conflicting data from epidemiologic studies of CA-MRSA infections and various murine disease models. Identifying specialized pathogenic traits of CA-MRSA and the concerted regulation of these factors remains a challenge that will foster development of vaccines and therapies designed to control CA-MRSA infections. This review focuses on the current status of molecular epidemiology associated with CA-MRSA in Taiwan and progresses toward understanding the enhanced virulence properties of CA-MRSA, with an emphasis on the role of Panton-Valentine leukocidin.     

Scabies

Scabies is a contagious skin infestation caused by a mite. It causes significant global morbidity, with an estimated 300 million cases annually. Although it can affect individuals at any socioeconomic level, individuals who live in poverty or in overcrowded conditions are at much higher risk for scabies. Lack of local expertise can result in failure to recognize scabies, leading to delayed diagnosis and inadequate treatment of cases and contacts. Scabies disproportionately affects many Indigenous (First Nations, Inuit, Métis) communities where risk factors are present. Scabies risk is also higher in young children, the elderly and immunocompromised individuals. Institutional outbreaks of scabies have also been reported. Apart from a very itchy rash, scabies can lead to secondary bacterial infections and related complications, as well as to stigmatization, depression, insomnia and significant financial costs. Topical antiscabies lotions are still the mainstay of treatment, but oral ivermectin has also proven effective under certain circumstances. Asymptomatic and symptomatic household members should all be treated at the same time. In Canada and globally, the presence of scabies is usually a symptom of poor living conditions and a sign that basic necessities need improvement. Clinicians who work with Indigenous communities can improve their ability to diagnose and treat scabies, and should advocate for better living conditions where scabies is prevalent.     

Polymerase chain reaction detection of Kingella kingae in children with culture-negative septic arthritis in eastern Ontario

BACKGROUND:

The bacterium Kingella kingae may be an under-recognized cause of septic arthritis in Canadian children because it is difficult to grow in culture and best detected using molecular methods.

OBJECTIVES:

To determine whether K kingae is present in culture-negative joint fluid specimens from children in eastern Ontario using polymerase chain reaction (PCR) detection methods.

METHODS:

K kingae PCR testing was performed using residual bacterial culture-negative joint fluid collected from 2010 to 2013 at a children’s hospital in Ottawa, Ontario. The clinical features of children with infections caused by K kingae were compared with those of children with infections caused by the ‘typical’ septic arthritis bacteria, Staphylococcus aureus and Streptococcus pyogenes.

RESULTS:

A total of 50 joint fluid specimens were submitted over the study period. Ten were culture-positive, eight for S aureus and two for S pyogenes. Residual joint fluid was available for 27 of the 40 culture-negative specimens and K kingae was detected using PCR in seven (25.93%) of these samples. Children with K kingae were significantly younger (median age 1.7 versus 11.3 years; P=0.01) and had lower C-reactive protein levels (median 23.8 mg/L versus 117.6. mg/L; P=0.01) than those infected with other bacteria.

CONCLUSIONS:

K kingae was frequently detected using PCR in culture-negative joint fluid specimens from children in eastern Ontario. K kingae PCR testing of culture-negative joint samples in children appears to be warranted.     

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.     

Biologic response modifiers to decrease inflammation: Focus on infection risks

Biologic response modifiers are a novel class of drugs used by sub-specialists to treat immune-mediated conditions such as juvenile idiopathic arthritis and inflammatory bowel disease. Also known as ‘cytokine inhibitors’, they are proteins whose purpose is to block the action of cytokines involved in inflammation. The desired therapeutic effect is to reduce or control inflammation. Tumour necrosis factor-α (TNF-α) inhibitors are the prototypes, but newer agents in this class target other cytokines such as interleukin(IL)-6, IL-12, and IL-23, or the proteins that target cytokine receptors on lymphocytes. They typically act by inhibiting the normal inflammatory processes involved in the immune response, particularly for macrophages. These agents are often used in combination with other immunosuppressive drugs such as methotrexate or steroids. The immune-modulating effects can persist days to weeks after discontinuation. Evidence indicates that patients treated with biologic response modifiers are at higher risk of tuberculosis infection and may be at higher risk of fungal or other infections with intracellular pathogens. This practice point offers guidelines on the preventive strategies that should be used in patients who will be or who are taking these immune-modifying agents.     

Sexually transmitted infections in adolescents: Maximizing opportunities for optimal care

Sexually transmitted infections are a growing public health concern in Canada, with rates of Chlamydia trachomatis infection, gonorrhea and syphilis increasing among adolescents and young adults. The present practice point outlines epidemiology, risk factors, laboratory testing and management for C trachomatis, Neisseria gonorrhoeae and Treponema pallidum, with a lesser focus on HIV. The need for test-of-cure and indications for further investigations are also discussed. The importance of maximizing opportunities to screen for and treat sexually transmitted infections in this age group is highlighted.     

Recommendations for the prevention of neonatal ophthalmia

Despite the decreasing prevalence of Neisseria gonorrhoeae in Canada, the Canadian Paediatric Society recommends that, as soon as possible after birth, all infants receive prophylaxis with silver nitrate, tetracycline or erythromycin, to reduce the risk of neonatal ophthalmia due to this organism. The use of these agents may also provide some benefit in the prevention of ophthalmia due to other organisms. As well, the Canadian Paediatric Society supports routine pre-natal screening for N gonorrhoeae and Chlamydia trachomatis, and the treatment of identified infections during pregnancy.     

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.