Community-acquired methicillin-resistant Staphylococcus aureus infections in children

Environmental Methicillin-resistant Staphylococcus aureus Contamination, Persistent Colonization, and Subsequent Skin and Soft Tissue Infection

IMPORTANCE

The longitudinal association among persistent Staphylococcus aureus colonization, household environmental contamination, and recurrent skin and soft tissue infection (SSTI) is largely unexplored to date.

OBJECTIVES

To identify factors associated with persistent S aureus colonization and recurrent SSTI in households with children with community-associated methicillin-resistant S aureus (MRSA) SSTI.

DESIGN, SETTING, AND PARTICIPANTS

This 12-month prospective cohort study included 150 children with community-associated MRSA SSTI, 542 household contacts, and 154 pets enrolled from January 3, 2012, through October 20, 2015. A total of 5 quarterly home visits were made to 150 households in the St Louis, Missouri, region. Statistical analysis was performed from September 18, 2018, to January 7, 2020.

EXPOSURES

Covariates used in S aureus strain persistence and interval SSTI models included S aureus colonization and contamination measures, personal hygiene and sharing habits, health history, activities external to the home, and household characteristics (eg, cleanliness, crowding, home ownership, and pets). Serial samples to detect S aureus were collected from household members at 3 anatomic sites, from pets at 2 anatomic sites, and from environmental surfaces at 21 sites.

MAIN OUTCOMES AND MEASURES

Molecular epidemiologic findings of S aureus isolates were assessed via repetitive-sequence polymerase chain reaction. Individual persistent colonization was defined as colonization by an identical strain for 2 consecutive samplings. Longitudinal, multivariable generalized mixed-effects logistic regression models were used to assess factors associated with persistent S aureus personal colonization, environmental contamination, and interval SSTI.

RESULTS

Among 692 household members in 150 households, 326 (47%) were male and 366 (53%) were female, with a median age of 14.82 years (range, 0.05-82.25 years). Of 540 participants completing all 5 samplings, 213 (39%) were persistently colonized with S aureus, most often in the nares and with the strain infecting the index patient at enrollment. Nine pets (8%) were persistently colonized with S aureus. Participants reporting interval intranasal mupirocin application were less likely to experience persistent colonization (odds ratio [OR], 0.44; 95% credible interval [CrI], 0.30-0.66), whereas increasing strain-specific environmental contamination pressure was associated with increased individual persistent colonization (OR, 1.17; 95% CrI, 1.06-1.30). Strains with higher colonization pressure (OR, 1.47; 95% CrI, 1.25-1.71) and MRSA strains (OR, 1.57; 95% CrI, 1.16-2.19) were more likely to persist. Seventy-six index patients (53%) and 101 household contacts (19%) reported interval SSTIs. Individuals persistently colonized with MRSA (OR, 1.56; 95% CrI, 1.17-2.11), those with a history of SSTI (OR, 2.55; 95% CrI, 1.88-3.47), and index patients (OR, 1.54; 95% CrI, 1.07-2.23) were more likely to report an interval SSTI.

CONCLUSIONS AND RELEVANCE

The study findings suggest that recurrent SSTI is associated with persistent MRSA colonization of household members and contamination of environmental surfaces. Future studies may elucidate the effectiveness of specific combinations of personal decolonization and environmental decontamination efforts in eradicating persistent strains and mitigating recurrent SSTIs.

Mupirocin for Staphylococcus aureus Decolonization of Infants in Neonatal Intensive Care Units

: media-1vid110.1542/5849573989001PEDS-VA_2018-1565Video Abstract BACKGROUND AND OBJECTIVES: Staphylococcus aureus (SA) is the second leading cause of late-onset sepsis among infants in the NICU. Because colonization of nasal mucosa and/or skin frequently precedes invasive infection, decolonization strategies, such as mupirocin application, have been attempted to prevent clinical infection, but data supporting this approach in infants are limited. We conducted a phase 2 multicenter, open-label, randomized trial to assess the safety and efficacy of intranasal plus topical mupirocin in eradicating SA colonization in critically ill infants.

METHODS

Between April 2014 and May 2016, infants <24 months old in the NICU at 8 study centers underwent serial screening for nasal SA. Colonized infants who met eligibility criteria were randomly assigned to receive 5 days of mupirocin versus no mupirocin to the intranasal, periumbilical, and perianal areas. Mupirocin effects on primary (day 8) and persistent (day 22) decolonization at all three body sites were assessed.

RESULTS

A total of 155 infants were randomly assigned. Mupirocin was generally well tolerated, but rashes (usually mild and perianal) occurred significantly more often in treated versus untreated infants. Primary decolonization occurred in 62 of 66 (93.9%) treated infants and 3 of 64 (4.7%) control infants (P < .001). Twenty-one of 46 (45.7%) treated infants were persistently decolonized compared with 1 of 48 (2.1%) controls (P < .001).

CONCLUSIONS

Application of mupirocin to multiple body sites was safe and efficacious in eradicating SA carriage among infants in the NICU; however, after 2 to 3 weeks, many infants who remained hospitalized became recolonized.

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

OBJECTIVE

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

METHODS

Between 2012 and 2015, 150 children with CA-MRSA infections and their household contacts and pets were enrolled in this cross-sectional study in metropolitan Saint Louis, MO. Cultures to detect S. aureus were collected from 3 anatomic sites of household members, 2 dog/cat sites, and 21 environmental surfaces in each household. Molecular epidemiology of S. aureus isolates was determined via repetitive-sequence PCR. Generalized linear models were developed to identify factors associated with S. aureus/MRSA household contamination.

RESULTS

MRSA was recovered from environmental surfaces in 69 (46%) households (median 2 surfaces [range 1-18]). The enrollment infecting strain type was the most common strain recovered from the environment in most (64%) households. In generalized linear models, factors associated with a higher proportion of MRSA-contaminated environmental surfaces were household member MRSA colonization burden, MRSA as the dominant S. aureus strain colonizing household members, more strain types per household member, index case African-American race, and renting (vs. owning) the home. Of 132 pets, 14% were colonized with MRSA. Pets whose primary caretaker was MRSA-colonized were more likely to be MRSA-colonized than pets whose primary caretaker was not MRSA-colonized (50% vs. 4%, p < 0.001).

CONCLUSIONS

Household environments and pet dogs and cats serve as reservoirs of MRSA. Household member MRSA colonization burden predicts environmental MRSA contamination. Longitudinal studies will inform the directionality of household transmission.

Spatial relationships among public places frequented by families plagued by methicillin-resistant Staphylococcus aureus

Objective

To understand factors associated with community-associated methicillin-resistant Staphylococcus aureus (CA-MRSA) acquisition and infection, we mapped public places (including personal service establishments, fitness centers, pools, schools, and daycares) visited by members of households affected by CA-MRSA skin and soft tissue infection.

Results

From January 2012 to October 2015, households of children with CA-MRSA SSTI in metropolitan St. Louis were enrolled in the HOME: Household Observation of MRSA in the Environment study. Addresses of public places visited within 3 months of enrollment were reported by 671 participants and were analyzed using a geographic information system (GIS). The Nearest Neighbor Tool in ArcGIS assessed clustering of public places within the study region. Public places were significantly clustered within the study area compared to the expected distance between locations (p < 0.001). Additionally, one-third (48/150) of participating households visited at least one public place in common with other households. No significant relationship between participants visiting the public places within 3 months of enrollment and subsequent colonization or SSTI were found. Understanding community behavior is critical to informing public health initiatives to reduce the prevalence of CA-MRSA infections.

Methicillin-Resistant Staphylococcus aureus: The Effects Are More Than Skin Deep

OBJECTIVES

To assess the psychosocial effects of a methicillin-resistant Staphylococcus aureus (MRSA) diagnosis on the households of children with MRSA skin and soft tissue infection (SSTI).

STUDY DESIGN

We constructed and administered an interview to the primary caregiver within the home of a child with a history of MRSA SSTI.

RESULTS

Seventy-six households were enrolled. Survey responses were analyzed and grouped into 4 themes: health behavior changes, disclosure, social interactions, and knowledge/awareness. The most common theme was disclosure; 91% of participants reported sharing their child's MRSA diagnosis with someone outside of the household. Forty-two percent of respondents reported a change in the manner in which household contacts interacted as a result of the index patient's MRSA diagnosis, including isolating the index patient from other children in the household. Many households reported adopting enhanced personal hygiene behaviors and environmental cleaning routines. Thirty-eight percent of participating households reported altering how they interact with people outside of their home, largely to avoid spreading MRSA to vulnerable individuals. In addition, many participants perceived that others regarded them with caution, especially at daycare, whereas other affected households were excluded from family gatherings.

CONCLUSION

Primary caregivers of children with MRSA SSTI reported changing their health behaviors, altering their interactions with people outside of their home, and feeling isolated by others in response to their child's MRSA diagnosis. The findings of our study highlight a need for community interventions and education to prevent the negative psychosocial repercussions associated with MRSA.

Impact of Systemic Antibiotics on Staphylococcus aureus Colonization and Recurrent Skin Infection

Background

Staphylococcus aureus colonization poses risk for subsequent skin and soft tissue infection (SSTI). We hypothesized that including systemic antibiotics in the management of S. aureus SSTI, in conjunction with incision and drainage, would reduce S. aureus colonization and incidence of recurrent infection.

Methods

We prospectively evaluated 383 children with S. aureus SSTI requiring incision and drainage and S. aureus colonization in the anterior nares, axillae, or inguinal folds at baseline screening. Systemic antibiotic prescribing at the point of care was recorded. Repeat colonization sampling was performed within 3 months (median, 38 days; interquartile range, 22-50 days) in 357 participants. Incidence of recurrent infection was ascertained for up to 1 year.

Results

Participants prescribed guideline-recommended empiric antibiotics for purulent SSTI were less likely to remain colonized at follow-up sampling (adjusted hazard ratio [aHR], 0.49; 95% confidence interval [CI], .30-.79) and less likely to have recurrent SSTI (aHR, 0.57; 95% CI, .34-.94) than those not receiving guideline-recommended empiric antibiotics for their SSTI. Additionally, participants remaining colonized at repeat sampling were more likely to report a recurrent infection over 12 months (aHR, 2.37; 95% CI, 1.69-3.31). Clindamycin was more effective than trimethoprim-sulfamethoxazole (TMP-SMX) in eradicating S. aureus colonization (44% vs 57% remained colonized, P = .03) and preventing recurrent SSTI (31% vs 47% experienced recurrence, P = .008).

Conclusions

Systemic antibiotics, as part of acute SSTI management, impact S. aureus colonization, contributing to a decreased incidence of recurrent SSTI. The mechanism by which clindamycin differentially affects colonization and recurrent SSTI compared to TMP-SMX warrants further study.

Predictors of Adverse Outcomes in Children With Staphylococcus aureus Bacteremia

OBJECTIVES

Staphylococcus aureus bacteremia is a common infection, associated with significant morbidity and mortality in children. Factors associated with adverse treatment outcomes are poorly understood in the pediatric population.

METHODS

Our study compared clinical and microbiologic characteristics of children admitted during a 5-year period (2007-2012) to a large university-based hospital and found to have S aureus bacteremia with outcome measures, in order to identify risk factors associated with treatment failure (defined as 30-day mortality, delayed microbiologic resolution, or recurrence of S aureus bacteremia within 60 days of completing effective antibiotic therapy).

RESULTS

In all, 71 patients were found to have S aureus bacteremia, and of these, 17 patients (24%) experienced treatment failure. Based on the logistic regression model, only high vancomycin minimum inhibitory concentration in combination with a high-risk source of infection (i.e., infected graft or device, intra-abdominal infection, or respiratory tract infection) was significantly associated with risk of treatment failure.

CONCLUSIONS

Infection associated with a high-risk source may increase the chance of treatment failure in pediatric patients with S aureus bacteremia. Vancomycin minimum inhibitory concentration alone was not found to be a predictor of treatment outcomes.

Clindamycin-susceptibility Rates of Methicillin-resistant Staphylococcus aureus Varies by Infection Type in Pediatric Patients

Hospital-wide antibiograms provide general susceptibility patterns. Specific antibiograms were created for methicillin-resistant Staphylococcus aureus isolates based on infection process and epidemiology. Using clinical microbiology laboratory data and patient profiles, high clindamycin resistance rates were seen for nonskin and soft tissue infections and noncommunity-associated methicillin-resistant S. aureus isolates.

Prevention of Recurrent Staphylococcal Skin Infections

Staphylococcus aureus infections pose a significant health burden. The emergence of community-associated methicillin-resistant S aureus has resulted in an epidemic of skin and soft tissue infections (SSTI), and many patients experience recurrent SSTI. As S aureus colonization is associated with subsequent infection, decolonization is recommended for patients with recurrent SSTI or in settings of ongoing transmission. S aureus infections often cluster within households, and asymptomatic carriers serve as reservoirs for transmission; therefore, a household approach to decolonization is more effective than measures performed by individuals alone. Novel strategies for the prevention of recurrent SSTI are needed.

Is Trimethoprim-Sulfamethoxazole a Valid Alternative in the Management of Infections in Children in the Era of Community-Acquired Methicillin-Resistant Staphylococcus aureus? A Comprehensive Systematic Review

Objective. To evaluate the use of TMP-SMX compared with other options available for the treatment of children with community-acquired methicillin-resistant Staphylococcus aureus (CA-MRSA) infections. Data Sources. The following databases were searched: Medline and PreMedline (OivdSP interface); Excerpta Medica Database (EMBASE; Elsevier interface); Cumulative Index to the Nursing and Allied Health Literature (CINAHL; EbscoHost interface); Sciences Citation Index Expanded (SCI-EXPANDED; Web of Science interface); Cochrane Library (Wiley interface); Scopus (Elsevier interface), and DARE, HTA (CRD interface). The search strategy was the one developed by SIGN to identify randomized clinical trials and systematic reviews. Also, we conducted a hand review of all reference lists of included studies. No language or data limits were added. The last search was done on October 1, 2015. Main key words were trimethoprim or trimethoprim-sulfamethoxazole combination and Staphylococcus aureus. Study Selection. Only randomized controlled trials comparing TMP-SMX versus any other antibiotic as the first-line treatment in CA-MRSA infections in children were included. Articles were reviewed by 2 reviewers, and in case of discrepancy, the final decision was made by the study coordinator. Data Extraction. Only 27 out of 364 articles identified were randomized controlled trials and only 4 fulfilled the eligibility criteria (Jadad score >3). Data Synthesis. Evidence found only referred to use of TMP-SMX in soft tissue infections. Heterogeneity among studies precluded meta-analysis. Conclusions. Available evidence is not conclusive to promote or refuse TMP-SMX as first-line treatment in CA-MRSA infections in children. Additional well-designed studies are required to fsurther elucidate this issue.

Characterization of Staphylococcus aureus infections in children with Down syndrome

Staphylococcus aureus infections in the Down syndrome (DS) population have not been well characterized. This study determined clinical and molecular characteristics of S. aureus infections in children with DS followed at Texas Children's Hospital (TCH), from 2001 to 2011. Patients were retrospectively identified from an ongoing S. aureus surveillance study. Medical records were reviewed. Isolates were characterized by antimicrobial susceptibility, pulsed-field gel electrophoresis patterns, and detection of PVL genes (pvl), mupA (high-level mupirocin resistance gene), smr (chlorhexidine resistance conferring gene), and Staphylococcal Chromosomal Cassette mec (SCCmec) type. Twenty-six patients with DS had a total of 34 S. aureus infections (8 recurrent); 61% were MRSA. DS patients represented 16.8 per 10,000 community onset S. aureus infections seen at TCH. Among 26 initial infections 17 were skin and soft tissue (SSTI), 7 were outer or middle ear and 2 were invasive infections. Seventeen patients were hospitalized. Thirteen (65%) of 20 available isolates were USA300, 14 were pvl+, 5 were mupA+, and 8 were smr+. Five of 8 (63%) recurrent infections were ear infections. All 4 recurrent ear isolates available for study were smr+, ciprofloxacin non-susceptible and treated with ciprofloxacin otic drops. S. aureus infections among patients with DS were similar in presentation to other patient groups, except for a greater proportion being associated with ear infections. Seventy percent of ear fluid isolates carried antiseptic and fluoroquinolone resistance genes. A study of a greater number of DS patients is warranted to further explore these findings.

Suppurative cervical lymphadenitis in infancy: microbiology and sociology

OBJECTIVE

To investigate the associations between patient age, sociological factors, and the microbiology of pediatric neck infections.

METHODS

Retrospective chart review of children up to 5 years old who underwent surgical management of suppurative cervical lymphadenitis.

RESULTS

A total of 76 individuals met inclusion criteria; 93% of culture-positive infections were caused by Staphylococcus aureus in infants, compared with 59% in children between 13 months and 5 years of age (P = .002). Of the S aureus isolates, 51% were methicillin-resistant S aureus (MRSA) and 49% were methicillin-sensitive S aureus. Methicillin resistance was associated with African American race (P = .004); 67% of participants received empirical antibiotics prior to admission. Of these, 73% received antibiotics in the β-lactam class, and 25% received treatment with clindamycin.

CONCLUSIONS

Incidence of MRSA is high in infants with cervical lymphadenitis who fail empirical antibiotic therapy and require surgical management. Empirical coverage for cervical lymphadenitis with β-lactam antibiotics may provide inadequate coverage for early infection in this population.

Methicillin-resistant Staphylococcus aureus: decolonization and prevention prescribing practices for children treated with skin abscesses/boils in a pediatric emergency department

OBJECTIVE

This study aimed to describe methicillin-resistant Staphylococcus aureus (MRSA) eradication/prevention practices of clinicians managing patients with skin and soft tissue infections (SSTIs), specifically, in those patients undergoing abscess incision and drainage (I&D) in a pediatric emergency department (ED).

METHODS

A retrospective cohort study was performed for children aged 0 to 18 years old undergoing I&D of cutaneous abscess between January 1, 2011, and December 31, 2011, in the Cincinnati Children's Hospital Medical Center ED.

RESULTS

Five hundred seventy-five patients underwent abscess I&D during our study period. Approximately 25% of our population had previous history of MRSA, SSTI, or boil/abscess; in addition, 26% of our population had a household family member with a previous history of MRSA, SSTI, or boil/abscess. Wound cultures were obtained in 399 (69%) of 575 of I&D abscesses, and of these, 57% of the I&D abscesses grew MRSA. Of all patients, only 3.7% (21 patients) had documentation of MRSA eradication/prevention instructions for patient/family.

CONCLUSIONS

Methicillin-resistant S aureus eradication/prevention discussions are not commonly included in discharge instructions for patients undergoing abscess I&D. Given the significant proportion with previous MRSA infection, the ED may be a setting to provide instructions to patients/families with recurrent infections.

Efficacy of Dilute Hypochlorite Solutions and an Electrochemically Activated Saline Solution Containing Hypochlorous Acid for Disinfection of Methicillin-Resistant Staphylococcus aureus in a Pig Skin Model

Recurrent skin and soft-tissue infections (SSTIs) due to Staphylococcus aureus are a common problem in children and adults. Many of these SSTIs are caused by a community-associated methicillin-resistant S. aureus (MRSA) strain designated USA300. Dilute bleach baths are commonly used as part of decolonization regimens for recurrent SSTI, particularly in children. However, limited data are available on the microbiological efficacy of dilute bleach on skin, and optimal concentrations are unknown. Recent practice guidelines for MRSA from the Infectious Diseases Society of America recommend a teaspoon of household bleach per gallon of bath water (1.3 μL/mL or a quarter cup per quarter tub of water) for 15 minutes twice weekly. On the basis of in vitro data, Fisher et al suggested that a higher concentration (2.5 μL/mL or a half cup per quarter tub of water) might be more effective (more than a 3-log reduction in MRSA in 5 minutes versus a 2-log reduction for a 1.2-μL/mL concentration). In contrast, more dilute bleach solutions (eg, a quarter cup of 6% sodium hypochlorite per bathtub full of water) for 5 days in combination with intranasal mupirocin were effective for eradication of colonization in a recent randomized trial, but 29% of patients in the mupirocin/bleach bath group developed recurrent colonization within 4 months. Here, we used a pig skin model to examine the effectiveness of various concentrations of dilute bleach solution and an electrochemically activated saline solution containing 0.025% hypochlorous acid (Vashe; PuriCore) for disinfection of MRSA on skin. Vashe is safe for use on skin and is commercially available as a wound care product.

Contamination of environmental surfaces with Staphylococcus aureus in households with children infected with methicillin-resistant S aureus

IMPORTANCE

Household environmental surfaces may serve as vectors for the acquisition and spread of methicillin-resistant Staphylococcus aureus (MRSA) among household members, although few studies have evaluated which objects are important reservoirs of MRSA.

OBJECTIVES

To determine the prevalence of environmental MRSA contamination in households of children with MRSA infection; define the molecular epidemiology of environmental, pet, and human MRSA strains within households; and identify factors associated with household MRSA contamination.

DESIGN, SETTING, AND PARTICIPANTS

Fifty children with active or recent culture-positive community-associated MRSA infection were enrolled from 2012 to 2013 at St Louis Children's Hospital and at community pediatric practices affiliated with the Washington University Pediatric and Adolescent Ambulatory Research Consortium in St Louis, Missouri.

MAIN OUTCOMES AND MEASURES

Samples of participants' nares, axillae, and inguinal folds were cultured to detect S aureus colonization. Samples of 21 household environmental surfaces, as well as samples obtained from pet dogs and cats, were cultured. Molecular typing of S aureus strains was performed by repetitive-sequence polymerase chain reaction to determine strain relatedness within households.

RESULTS

Methicillin-resistant S aureus was recovered from samples of environmental surfaces in 23 of the 50 households (46%), most frequently from the participant's bed linens (18%), television remote control (16%), and bathroom hand towel (15%). It colonized 12% of dogs and 7% of cats. At least 1 surface was contaminated with a strain type matching the participant's isolate in 20 households (40%). Participants colonized with S aureus had a higher mean (SD) proportion of MRSA-contaminated surfaces (0.15 [0.17]) than noncolonized participants (0.03 [0.06]; mean difference, 0.12 [95% CI, 0.05-0.20]). A greater number of individuals per 1000 ft 2 (93 m2) were also associated with a higher proportion of MRSA-contaminated surfaces (β = 0.34, P = .03). The frequency of cleaning household surfaces was not associated with S aureus environmental contamination.

CONCLUSIONS AND RELEVANCE

Methicillin-resistant S aureus strains concordant with infecting and colonizing strains are present on commonly handled household surfaces, a factor that likely perpetuates MRSA transmission and recurrent disease. Future studies are needed to determine methods to eradicate environmental contamination and prevent MRSA transmission in households.

Ceftaroline activity tested against bacterial isolates from pediatric patients: results from the assessing worldwide antimicrobial resistance and evaluation program for the United States (2011-2012)

BACKGROUND

Ceftaroline, the active form of ceftaroline fosamil, is a cephalosporin with broad-spectrum bactericidal activity against resistant Gram-positive organisms, including methicillin-resistant Staphylococcus aureus, ceftriaxone-resistant Streptococcus pneumoniae and many Enterobacteriaceae species. Ceftaroline fosamil is approved in the United States for treatment of acute bacterial skin and skin structure infections and community-acquired bacterial pneumonia in adults.

METHODS

A total of 5291 consecutive unique pediatric patient strains of clinical significance were collected from 157 US medical centers. The isolates were identified locally and forwarded to a central monitoring laboratory for reference antimicrobial susceptibility testing. S. pneumoniae isolates from the 2011 to 2012 respiratory season were serotyped. Susceptibility results were analyzed according to patient age as follows: ≤ 1 years old (yo; 1857 strains); 2-5 (1342); 6-12 (1281) and 13-17 (811).

RESULTS

Methicillin-resistant Staphylococcus aureus rates were slightly lower in isolates from patients 13-17 yo (39.9%) compared with other age groups (48.2-51.5%), and ceftaroline was consistently active against S. aureus isolates from all 4 age groups [minimal inhibitory concentration (MIC50/90): 0.25-05/1 μg/mL; 99.8-100.0% susceptible]. Overall, 99.8% of methicillin-resistant Staphylococcus aureus were ceftaroline susceptible (MIC50/90: 0.5/1 μg/mL). All S. pneumoniae strains (1178) were ceftaroline susceptible (MIC50/90: ≤ 0.015/0.12 μg/mL), whereas ceftriaxone susceptibility varied from only 84.8 (≤ 1 yo) to 89.7% (13-17 yo). 19A was the most frequent serotype identified among S. pneumoniae and these isolates exhibited low susceptibility to ceftriaxone (42.4%) and most other antimicrobials tested. The highest ceftaroline MIC among Haemophilus influenzae (587 strains) was 0.12 μg/mL (100.0% susceptible), and β-lactamase production rates varied from 24.2 (13-17 yo) to 30.1% (6-12 yo); 27.9% overall. Ceftaroline was also active against β-hemolytic streptococci (556 strains, highest MIC, 0.06 μg/mL). Extended-spectrum β-lactamase (ESBL)-phenotype rates among Escherichia coli/Klebsiella spp. were 6.0/5.1, 11.0/11.5, 5.1/8.3 and 11.4/14.7% for the ≤ 1, 2-5, 6-12 and 13-17 yo age groups, respectively. Ceftaroline exhibited good activity against non-ESBL phenotype strains of E. coli and Klebsiella spp. (MIC90: 0.25 μg/mL for both organisms), but had limited activity against ESBL-producing strains.

CONCLUSION

Ceftaroline demonstrated potent in vitro activity when tested against S. aureus, S. pneumoniae, H. influenzae, β-hemolytic streptococci and non-ESBL-phenotype E. coli and Klebsiella spp. strains isolated from pediatric patients, independent of patient age.

Recurrent community-associated Staphylococcus aureus infections in children presenting to Texas Children's Hospital in Houston, Texas

BACKGROUND

There are limited data characterizing recurrent staphylococcal disease in children. We sought to define the clinical features and laboratory findings of children with recurrent community-associated Staphylococcus aureus infections presenting to Texas Children's Hospital in Houston, TX.

METHODS

Medical records of children with recurrent, culture-proven community-associated S. aureus infections at Texas Children's Hospital from 8/1/2001 to 7/29/2009 were reviewed, and antibiotic susceptibility patterns were obtained for all S. aureus isolates.

RESULTS

Six hundred ninety-four otherwise healthy patients presented to Texas Children's Hospital with 2-7 episodes of community-associated S. aureus infection, accounting for 1495 encounters, 823 hospitalizations and 3337 inpatient days. In 90% of patients with ≤12 months separating their initial and recurrent infections, the methicillin susceptibility of the initial and recurrent isolates was the same, compared with 79% of patients with > 12 months separating their infections. The overall antibiotic susceptibility pattern did not change between isolates in 71% of otherwise healthy children compared with only 33% of children with eczema. Ninety-two percent of otherwise healthy children had only recurrent skin and soft tissue infections; 8% had ≥1 non-skin and soft tissue infections. The location of skin and soft tissue infections varied by age, with children≤36 months of age being more likely to have ≥1 S. aureus infection located in the diaper area.

CONCLUSIONS

Our study demonstrates that recurrent staphylococcal disease requiring emergency center or inpatient care is common, accounting for significant utilization of hospital resources. Children with recurrent staphylococcal infections are likely to have repeated infections from the same staphylococcal strain (by antibiotic susceptibility pattern), indicating that persistent colonization, frequent exposure to others who are chronically colonized, or environmental contamination is playing a role in recurrent disease. Finally, our study emphasizes the need for repeat cultures in children with recurrent disease, as 29% of healthy children and 67% of children with a predisposing risk factor (such as eczema) have a change in the antibiotic susceptibility pattern between S. aureus isolates.

Factors associated with high resource utilization in pediatric skin and soft tissue infection hospitalizations

OBJECTIVE

To describe factors associated with prolonged lengths of stay (LOS) and increased charges for pediatric skin and soft tissue infection (SSTI) hospitalizations.

METHODS

This study was a cross-sectional analysis of pediatric SSTI hospital discharges in 2009 within the Healthcare Cost and Utilization Project Kids' Inpatient Database. Outcomes were prolonged LOS (>75th percentile) and increased hospital charges (>75th percentile). Multivariate logistic regression controlling for patient and hospital level factors was conducted for 2009 data to assess associations among variables.

RESULTS

The 75th percentile for LOS was 3 days. Infants had higher odds of prolonged LOS than other age groups (<1 year: 1; 1-4 years: 0.70 [95% confidence interval (CI): 0.64-0.76]; 5-12 years: 0.69 [95% CI: 0.63-0.76]; 13-18 years: 1.01 [95% CI: 0.91-1.10]), as did all minority groups compared with white subjects (black subjects: 1.23 [95% CI: 1.09-1.38]; Hispanic subjects: 1.33 [95% CI: 1.20-1.47]; and other races: 1.30 [95% CI: 1.12-1.50]). Public payers compared with private payers (odds ratio: 1.17 [95% CI: 1.10-1.26]) also had increased odds of prolonged LOS. The 75th percentile for charges was $14 317. The adolescent-aged category had higher odds of charges >75th percentile compared with the age category <1 year (odds ratio: 1.54 [95% CI: 1.36-1.74]). All racial/ethnic minorities had higher odds of charges >75th percentile compared with white subjects (black subjects: 1.38 [95% CI: 1.17-1.62]; Hispanic subjects: 1.90 [95% CI: 1.59-2.26]; and other races: 1.26 [95% CI: 1.06-1.50]).

CONCLUSIONS

Vulnerable populations, including infants, racial/ethnic minorities, and publicly insured children, had higher odds of increased resource utilization during hospitalizations for SSTIs. The findings of this study provide potential targets for future preventive and public health interventions.

Measurement and Impact of Staphylococcus aureus Colonization Pressure in Households

BACKGROUND

Methicillin-resistant Staphylococcus aureus (MRSA) "colonization pressure" (CP) predicts infections in hospitals. We applied the CP concept to staphylococcal transmission within households. We tested the hypothesis that children with S aureus skin and soft tissue infection (SSTI) plus colonization ("cases") with higher baseline household CP (HHCP) would be at greater risk for persistent colonization and recurrent SSTI during study period.

METHODS

We collected baseline colonization swabs from 92 cases and 296 of their household contacts. Cases underwent decolonization. S aureus HHCP was calculated as the proportion of colonized household contacts at baseline (excluding cases). S aureus colonization and recurrent SSTI in cases were followed for 12 months.

RESULTS

Overall, median S aureus HHCP was 60% (mean = 55%). For cases colonized with MRSA, median MRSA HHCP was 11% (mean 29%); methicillin-susceptible S aureus (MSSA)-colonized cases had a median MSSA HHCP of 50% (mean = 49%). Over 1 year, MRSA HHCP was an independent risk factor for persistent MRSA colonization in cases (each 10-unit increase in HHCP associated with an adjusted odds ratio of 1.25; 95% confidence interval, 1.06-1.47). HHCP was not associated with recurrent SSTI in cases.

CONCLUSIONS

MRSA HHCP is associated with persistent colonization in outpatients. Further studies are needed to determine the relationship between persistent colonization of household contacts, environmental contamination, and SSTI.

Osteomyelitis and beyond

Musculoskeletal infections are a cause of considerable morbidity in children. Symptoms and signs are often nonspecific, and imaging is needed to define the anatomical location of infected tissue or fluid collections for diagnostic aspiration or biopsy. Prompt diagnosis and precise localization of the infection site has become even more imperative with the emergence and dissemination of highly invasive organisms such as community-acquired Staphylococcus aureus. Although radiography, bone scintigraphy and US continue to play a role, MRI is now the preferred imaging modality for definitive evaluation of pediatric musculoskeletal infections because of its capability of simultaneously assessing the osseous, articular and muscular structures without ionizing radiation exposure. This article focuses on the imaging characteristics of osteomyelitis, septic arthritis and pyomyositis and the differentiating features of potential mimics of infection.

Practices and procedures to prevent the transmission of skin and soft tissue infections in high school athletes

Skin and soft tissue infections (SSTIs) are frequent in student athletes and are often caused by community-associated methicillin-resistant Staphylococcus aureus (CA-MRSA). We evaluated the awareness of CA-MRSA among high school coaches and athletic directors in Missouri (n = 4,408) and evaluated hygiene practices affecting SSTI transmission. Of 1,642 (37%) respondents, 61% received MRSA educational information during the past year and 32% indicated their school had written guidelines for managing SSTIs in athletes. Coaches and athletic directors aware of written guidelines reported a lower incidence of SSTIs in student athletes (26%) compared to those without written policies (34%, p = .03). When confronted with SSTIs, 49% of respondents referred student athletes to the school nurse or a physician. A relationship exists between school policies for SSTI management and lower incidence of SSTIs. Educational initiatives by school nurses in conjunction with athletic staff may lead to practices that limit SSTIs in this at-risk population.

Effectiveness of measures to eradicate Staphylococcus aureus carriage in patients with community-associated skin and soft-tissue infections: a randomized trial

BACKGROUND

Despite a paucity of evidence, decolonization measures are prescribed for outpatients with recurrent Staphylococcus aureus skin and soft-tissue infection (SSTI).

OBJECTIVE

Compare the effectiveness of 4 regimens for eradicating S. aureus carriage.

DESIGN

Open-label, randomized controlled trial. Colonization status and recurrent SSTI were ascertained at 1 and 4 months.

SETTING

Barnes-Jewish and St. Louis Children's Hospitals, St. Louis, Missouri, 2007-2009.

PARTICIPANTS

Three hundred patients with community-onset SSTI and S. aureus colonization in the nares, axilla, or inguinal folds.

INTERVENTIONS

Participants were randomized to receive no therapeutic intervention (control subjects) or one of three 5-day regimens: 2% mupirocin ointment applied to the nares twice daily, intranasal mupirocin plus daily 4% chlorhexidine body washes, or intranasal mupirocin plus daily dilute bleach water baths.

RESULTS

Among 244 participants with 1-month colonization data, modified intention-to-treat analysis revealed S. aureus eradication in 38% of participants in the education only (control) group, 56% of those in the mupirocin group (P = .03 vs controls), 55% of those in the mupirocin and chlorhexidine group (P = .05), and 63% off those in the mupirocin and bleach group (P = .006). Of 229 participants with 4-month colonization data, eradication rates were 48% in the control group, 56% in the mupirocin only group (P = .40 vs controls), 54% in the mupirocin and chlorhexidine group (P = .51), and 71% in the mupirocin and bleach group (P = .02). At 1 and 4 months, recurrent SSTIs were reported by 20% and 36% of participants, respectively.

CONCLUSIONS

An inexpensive regimen of dilute bleach baths, intranasal mupirocin, and hygiene education effectively eradicated S. aureus over a 4-month period. High rates of recurrent SSTI suggest that factors other than endogenous colonization are important determinants of infection. Trial registration. ClinicalTrials.gov identifier: NCT00513799.

Household versus individual approaches to eradication of community-associated Staphylococcus aureus in children: a randomized trial

BACKGROUND

Community-associated Staphylococcus aureus infections often affect multiple members of a household. We compared 2 approaches to S. aureus eradication: decolonizing the entire household versus decolonizing the index case alone.

METHODS

An open-label, randomized trial enrolled 183 pediatric patients (cases) with community-onset S. aureus skin abscesses and colonization of anterior nares, axillae, or inguinal folds from 2008 to 2009 at primary and tertiary centers. Participants were randomized to decolonization of the case alone (index group) or of all household members (household group). The 5-day regimen included hygiene education, twice-daily intranasal mupirocin, and daily chlorhexidine body washes. Colonization of cases and subsequent skin and soft tissue infection (SSTI) in cases and household contacts were ascertained at 1, 3, 6, and 12 months.

RESULTS

Among 147 cases with 1-month colonization data, modified intention-to-treat analysis revealed S. aureus eradication in 50% of cases in the index group and 51% in the household group (P = 1.00). Among 126 cases completing 12-month follow-up, S. aureus was eradicated from 54% of the index group versus 66% of the household group (P = .28). Over 12 months, recurrent SSTI was reported in 72% of cases in the index group and 52% in the household group (P = .02). SSTI incidence in household contacts was significantly lower in the household versus index group during the first 6 months; this trend continued at 12 months.

CONCLUSIONS

Household decolonization was not more effective than individual decolonization in eradicating community-associated S. aureus carriage from cases. However, household decolonization reduced the incidence of subsequent SSTI in cases and their household contacts.

CLINICAL TRIALS REGISTRATION

NCT00731783.

MRSA otorrhea: A case series and review of the literature

Methicillin-resistant Staphylococcus aureus (MRSA) has become an increasingly common cause of difficult-to-treat head and neck infections. We report a retrospective analysis of 3 cases of MRSA otorrhea treated in our clinic between 2007 and 2009. Culture analysis of otorrhea isolates revealed MRSA infections with identical drug sensitivities. Treatment success was achieved using combinations of linezolid with gentamicin ear drops for 3 to 4 weeks or trimethoprim/sulfamethoxazole (TMP/SMX) with gentamicin drops for 6 weeks. This study illustrates the importance of determining individual drug sensitivities for optimal treatment and maintaining current knowledge of the local MRSA strains. Empiric combination therapy of TMP/SMX with gentamicin is an effective first-line treatment for MRSA otorrhea. Regional differences in clindamycin sensitivities warrant clinical discretion. Fluoroquinolones should be avoided because of high rates of resistance unless culture sensitivity determines that they are appropriate. First-line agents for severe infections include combination therapy with vancomycin or linezolid.

Community-acquired methicillin-resistant Staphylococcus aureus: a potential diagnosis for a 16-year-old athlete with knee pain

OBJECTIVE

This case report aims to raise awareness in chiropractic physicians of the prevalence of methicillin-resistant Staphylococcus aureus (MRSA) in adolescents who participate in sports activities and to alert the chiropractic physician of the necessity to consider potential diagnoses that are not within their typical clinical heuristic.

CLINICAL FEATURES

A 16-year-old adolescent girl entered the clinic with a complaint of left knee pain that had an insidious onset during her involvement in sports activities. Later that same day, her knee became enlarged, red, and had pustular formations with a discharge. She was taken to an urgent care facility and subsequently diagnosed with MRSA. Her history included treatment of a left knee musculoskeletal condition 6 weeks prior to which she had responded favorably.

INTERVENTIONS AND OUTCOMES

She was treated medically with an aggressive course of antibiotic therapy and excision of the furuncle. The chiropractic physician played a role in patient education and notifying local school authorities of the case.

CONCLUSION

Doctors of chiropractic must prepare themselves for the unexpected and remain open to diagnostic possibilities outside of the normal scope of practice. Knee pain or cellulitis of any type may require additional diagnostic and patient care protocols to make the correct diagnosis. With the incidence of community-acquired MRSA increasing at an alarming rate, it is certainly a diagnosis doctors of chiropractic should be aware of when treating patients, especially those involved in sports activities.

MRSA blistering distal dactylitis and review of reported cases

We describe a 6-month-old infant with blistering distal dactylitis. Bacterial culture from the skin lesion grew methicillin resistant Staphylococcus aureus. No carriage of this bacterial agent was identified in her family. She responded to vancomycin administration and incision and drainage of the lesion. This is the first reported case of methicillin resistant Staphylococcus aureus-associated blistering distal dactylitis in an infant.

Fusidic acid and clindamycin resistance in community-associated, methicillin-resistant Staphylococcus aureus infections in children of Central Greece

Introduction

In Greece, fusidic acid and clindamycin are commonly used for the empiric therapy of suspected staphylococcal infections.

Methods

The medical records of children examined at the outpatient clinics or admitted to the pediatric wards of the University General Hospital of Larissa, Central Greece, with community-associated staphylococcal infections from January 2003 to December 2009 were reviewed.

Results

Of 309 children (0-14 years old), 21 (6.8%) had invasive infections and 288 (93.2%) skin and soft tissue infections (SSTIs). Thirty-five patients were ≤30 days of age. The proportion of staphylococcal infections caused by a community-associated methicillin-resistant Staphylococcus aureus (CA-MRSA) isolate increased from 51.5% (69 of 134) in 2003-2006 to 63.4% (111 of 175) in 2007-2009 (P = 0.037). Among the CA-MRSA isolates, 88.9% were resistant to fusidic acid, 77.6% to tetracycline, and 21.1% to clindamycin. Clindamycin resistance increased from 0% (2003) to 31.2% (2009) among the CA-MRSA isolates (P = 0.011). Over the 7-year period, an increase in multidrug-resistant CA-MRSA isolates was observed (P = 0.004). One hundred and thirty-one (93.6%) of the 140 tested MRSA isolates were Panton-Valentine leukocidin-positive. Multilocus sequence typing of 72 CA-MRSA isolates revealed that they belonged to ST80 (n = 61), ST30 (n = 6), ST377 (n = 3), ST22 (n = 1), and ST152 (n = 1). Resistance to fusidic acid was observed in ST80 (58/61), ST30 (1/6), and ST22 (1/1) isolates.

Conclusion

In areas with high rate of infections caused by multidrug-resistant CA-MRSA isolates, predominantly belonging to the European ST80 clone, fusidic acid and clindamycin should be used cautiously as empiric therapy in patients with suspected severe staphylococcal infections.

Staphylococcus aureus: a continuously evolving and formidable pathogen in the neonatal intensive care unit

Staphylococcus aureus is a continuously evolving and formidable pathogen that has been a problem for both healthy and sick neonates for decades. Much focus over the past 20 years has been on hospital-associated methicillin-resistant S aureus (HA-MRSA); however, a global epidemic because of virulent community-associated MRSA (CA-MRSA) that has no "fitness cost" for carrying antibiotic-resistance genes has moved into neonatal intensive care units (NICUs). Recently, methicillin-susceptible S aureus has adopted some of the virulence factors of CA-MRSA and is an increasingly common cause of hospital-acquired infections in NICUs. This article reviews the changing epidemiology, clinical manifestations, and treatment of S aureus in neonates.

Pediatric abscess characteristics associated with hospital admission from the ED

OBJECTIVE

To determine the characteristics of pediatric soft tissue abscesses that result in hospital admission.

METHODS

All visits for soft tissue abscesses to the study emergency department (ED) were examined during 2008. Detailed records were reviewed to determine ED disposition, abscess size, location, presence of fever, duration of symptoms, previous antibiotic therapy, prior ED visit(s), and wound and blood culture results. Data were analyzed to determine which of these characteristics were associated with hospital admission from the ED.

RESULTS

Six hundred twenty-two patients met the inclusion criteria. One hundred thirteen (18%) patients were admitted to the hospital and 509 (82%) were discharged home. Compared to those sent home, abscesses resulting in admission were more likely to be located in the genital area (odds ratio [OR], 3.08; 95% confidence interval [CI], 1.37-6.90), breast (OR, 4.8; 95% CI, 1.08-21.4), or face (OR, 4.39; 95% CI, 1.86-10.3), and were more likely to be larger than 3 cm (OR, 3.66, 95% CI, 2.10-6.36). Patients who were admitted to the hospital were also more likely to have fever (OR, 5.93; 95% CI, 3.4-10.3) and have had a prior ED visit with the same complaint (OR, 3.81; 95% CI, 1.77-8.2). Seventy-seven percent of abscesses that were cultured were positive for methicillin-resistant Staphylococcus aureus.

CONCLUSIONS

Size and location (especially those in the genital region, breast, and face), appear to be associated with admission for pediatric abscesses. History of fever and previous ED visit also appear to be associated with hospital admission. Obtaining blood cultures for pediatric abscesses is likely of little clinical benefit.

Trends in methicillin-resistant Staphylococcus aureus anovaginal colonization in pregnant women in 2005 versus 2009

In 2005, the prevalence of methicillin-resistant Staphylococcus aureus (MRSA) anovaginal colonization in pregnant women at our center (Columbia University Medical Center) was 0.5%, and MRSA-colonized women were less likely to carry group B streptococcus (GBS). In this study, our objectives were to identify changing trends in the prevalence of MRSA and methicillin-susceptible S. aureus (MSSA) anovaginal colonization in pregnant women, to assess the association between MRSA and GBS colonization, and to characterize the MRSA strains. From February to July 2009, Lim broths from GBS surveillance samples were cultured for S. aureus. MRSA strains were identified by resistance to cefoxitin and characterized by MicroScan, staphylococcal cassette chromosome mec (SCCmec) typing, pulsed-field gel electrophoresis (PFGE), spa typing, and Panton-Valentine leukocidin PCR. A total of 2,921 specimens from different patients were analyzed. The prevalences of MSSA, MRSA, and GBS colonization were 11.8%, 0.6% and 23.3%, respectively. GBS colonization was associated with S. aureus colonization (odds ratio [OR], 1.9; 95% confidence interval [95% CI], 1.5 to 2.4). The frequencies of GBS colonization were similar in MRSA-positive (34.2%) versus MRSA-negative patients (21.8%) (P = 0.4). All MRSA isolates from 2009 and 13/14 isolates from 2005 were SCCmec type IV or V, consistent with community-associated MRSA; 12/18 (2009) and 0/14 (2005) isolates were the USA300 clone. Levofloxacin resistance increased from 14.3% (2005) to 55.6% (2009) (P = 0.028). In conclusion, the prevalence of MRSA anovaginal colonization in pregnant women in New York City, NY, remained stable from 2005 to 2009, and USA300 emerged as the predominant clone with a significant increase in levofloxacin-resistant isolates.

New patterns in the otopathogens causing acute otitis media six to eight years after introduction of pneumococcal conjugate vaccine

OBJECTIVE

To describe NP and AOM otopathogens during the time frame 2007 to 2009, 6 to 8 years after the introduction of 7-valent pneumococcal conjugate (PCV7) in the United States and to compare nasopharyngeal (NP) colonization and acute otitis media (AOM) microbiology in children 6 to 36 months of age having first and second AOM episodes with children who are otitis prone.

METHODS

Prospectively, the microbiology of NP colonization and AOM episodes was determined in 120 children with absent or infrequent AOM episodes. NP samples were collected at 7 routine visits between 6 and 30 months of age and at the time of AOM. For first and subsequent AOM episodes, middle ear fluid (MEF) was obtained by tympanocentesis. Eighty otitis prone children were comparatively studied. All 200 children received age-appropriate doses of PCV7.

RESULTS

We found PCV7 serotypes were virtually absent: (0.9% isolated from both NP and MEF) in both study groups. However, non-PCV7 serotypes replaced PCV serotypes such that the frequency of isolation of S. pneumoniae (Spn) was nearly equal to that of non-typeable Haemophilus influenzae (NTHi). M. catarrhalis (Mcat) was less common and Staphylococcus aureus infrequent in the NP and MEF from the 2 groups. The proportion of Spn, NTHi and Mcat causing AOM was similar in children with first and second AOM episodes compared to otitis prone children. However, oxacillin-resistant Spn isolated from the NP and MEF was 19% for the absent/infrequent and 58% for the otitis prone groups, P < 0.0001. Beta-lactamase producing NTHi occurred more frequently in the otitis prone group, P = 0.04.

CONCLUSIONS

Six to 8 years after widespread use of PCV7, Spn strains expressing vaccine-type serotypes have virtually disappeared from the NP and MEF of vaccinated children. NP colonization and AOM has changed to non-PCV7 strains of Spn. NTHi continues to be a major AOM pathogen. The otopathogens in first and second AOM and in otitis prone children are very similar although Spn and NTHi are more often antibiotic resistant in the otitis prone.

Methicillin-resistant Staphylococcus aureus in middle ear fluid of children

BACKGROUND

Methicillin-resistant Staphylococcus aureus (MRSA) infections and colonization in children have increased in recent years.

OBJECTIVE

This study examined the possible effect of this increase on MRSA isolation from middle ear fluid (MEF) of children.

METHOD

A retrospective descriptive study was performed using the electronic medical records of children cared for at the Alfred I. duPont Hospital for Children from 2003 to 2007. All MEF isolates obtained at tympanostomy tube placement for recurrent or chronic otitis media or from spontaneous drainage were tabulated and analyzed. Records of children whose MEF grew S aureus comprised our database.

RESULTS

A total of 920 MEF isolates were reviewed, of which 121 patients with S aureus in the MEF were identified. Twenty were excluded per protocol. In the cohort of 101 patients, 76 had methicillin-sensitive Staphylococcus aureus (MSSA; 75.3%) and 25 had MRSA (24.7%).

CONCLUSION

In this retrospective study, the authors demonstrated that among children with S aureus in the MEF, younger children (<3 years) were more likely to have MRSA.

Skin infection in children colonized with community-associated methicillin-resistant Staphylococcus aureus

OBJECTIVES

The relationship between community-associated methicillin-resistant Staphylococcus aureus (CA-MRSA) nasal colonization and subsequent infection in children is unknown. We sought to define risk factors for skin and soft tissue infection (SSTI) in community children.

METHODS

A prior study measured S. aureus nasal colonization prevalence for 1300 community children. To detect subsequent SSTI in these children or a household member, surveys were administered 6 and 12 months following enrollment.

RESULTS

SSTIs were reported by 56/708 (8.1%) respondents during the initial 6-month interval. SSTI developed in 6/26 (23%) initially colonized with MRSA, 16/194 (8%) with methicillin-sensitive S. aureus colonization, and 34/474 (7%) not colonized with S. aureus (MRSA vs. not MRSA, univariate analysis, p = 0.014). In multivariable analysis, factors associated with SSTI included history of SSTI in the child during the year preceding enrollment (p < 0.01) and SSTI in household contacts during the follow-up interval (p<0.01); MRSA nasal colonization approached statistical significance (p = 0.08).

CONCLUSIONS

In the current era of community MRSA transmission, SSTI is a disease of households, with recurrences in index cases and occurrences among household contacts. Children with MRSA colonization may be at risk for subsequent SSTI. Further study of MRSA transmission dynamics in households and preventive strategies should receive high priority.

Epidemiology of community-onset Staphylococcus aureus infections in pediatric patients: an experience at a Children's Hospital in central Illinois

Background

The nation-wide concern over methicillin-resistant Staphylococcus aureus (MRSA) has prompted many clinicians to use vancomycin when approaching patients with suspected staphylococcal infections. We sought to characterize the epidemiology of community-onset S. aureus infections in hospitalized children to assist local clinicians in providing appropriate empiric antimicrobial therapy.

Methods

From January 2005–June 2008, children (0–18 years old) admitted to the Children's Hospital of Illinois with community-onset S. aureus infections were identified by a computer-assisted laboratory-based surveillance and medical record review.

Results

Of 199 patients, 67 (34%) had invasive infections, and 132 (66%) had skin and soft tissue infections (SSTIs). Among patients with invasive infections, S. aureus isolates were more likely to be susceptible to methicillin (MSSA 63% vs. MRSA 37%), whereas patients with SSTIs, S. aureus isolates were more likely to be resistant to methicillin (MRSA 64% vs. MSSA 36%). Bacteremia and musculoskeletal infections were the most common invasive infections in both groups of S. aureus. Pneumonia with empyema was more likely to be caused by MRSA (P = 0.02). The majority (~90%) of MRSA isolates were non-multidrug resistant, even in the presence of healthcare-associated risk factors.

Conclusion

Epidemiological data at the local level is important for antimicrobial decision-making. MSSA remains an important pathogen causing invasive community-onset S. aureus infections among hospitalized children. In our hospital, nafcillin in combination with vancomycin is recommended empiric therapy in critically ill patients with suspected invasive staphylococcal infections. Because up to 25% of MSSA circulating in our area are clindamycin-resistant, clindamycin should be used cautiously as empiric monotherapy in patients with suspected invasive staphylococcal infections.

Improving therapeutic strategies for secondary bacterial pneumonia following influenza

Secondary bacterial pneumonia following influenza is an old problem, which is re-emerging. Despite rapid advances in our armamentarium of antimicrobials, the case-fatality rate for this frequent complication of influenza remains high. In some settings, common treatment options may actually contribute to poor outcomes, as rapid lysis of pathogenic bacteria on the backdrop of an activated immune system responding to influenza may lead to inflammatory damage in the lung. An understanding of the inter-related contributions of the antecedent viral infection, the invading bacteria and the host immune response is necessary to formulate an appropriate therapeutic approach. Prevention and resolution of these fulminant infections will require new approaches, including alternate treatment strategies, combination therapies targeting several aspects of the pathogenic process and, potentially, immunomodulation. In the not-so-distant future, strategies aimed at disarming pathogens without eliminating them may be more effective than our current treatment paradigms.

Ideal microbiological and pharmacological characteristics of a quality antimicrobial agent: comparing original and generic molecules

This article critically evaluates the main in vitro and in vivo studies published which compare generic with the original molecules, both those administered orally and parenterally. The authors indicate that caution should be used in assuming bioequivalence of the generic drug with its clinical efficacy in clinical practice. In fact, mild differences in the content of the active ingredient, less relevant in healthy volunteers, may have an impact in the actual population, which is heterogeneous for age, sex, weight, concomitant risk factors and severity of the underlying disease, as in critically ill patients, with consequences for the patient and ecosystem. Nowadays the requirements for authorization to commercialize a generic antimicrobial agent are focused on demonstration of bioequivalence to the original molecule, with a range variability of +/-20%. However this kind of trial is not sufficient to predict the actual profile in clinical practice, particularly in critically ill patients. Thus while generics can represent an opportunity for physicians, patients and healthcare systems the regulatory procedures do not seem exhaustive, and it is probably necessary to define an ad hoc technical standard of quality before their commercialization and to perform adequate clinical trials regarding efficacy and safety of the "equivalent molecule", especially for drugs used in critically ill patients.