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

Microbiological Monitoring in the System of Epidemiological Surveillance of Purulent-Septic Infections in a Multidisciplinary Hospital

The purpose of the research was to study epidemiological manifestations and etiological structure of sepsis in a multidisciplinary hospital for children.Materials and methods. An analysis of cases of 85 patients with a diagnosis of sepsis hospitalized in a multidisciplinary hospital at the regional level (Irkutsk) for the period 2013–2018 was carried out.Results and discussion. The most affected age groups are children under one year old (23.5 %) and from one year to two years (29.4 %). During the study period, 572 bacterial and fungal cultures, represented by 19 types of microorganisms, playing a leading role in the formation of the microbial ecology of the hospital, were isolated from patients with GPSI. In the structure of the GPSI microflora, gram-negative microorganisms are found in 49.8 % of cases, grampositive microbiota – in 30.1 %, fungi account for one fifth of all positive findings. A. baumannii and P. aeruginosa were sown more often from blood, sputum and abdominal cavity, and S. aureus and A. baumannii were the most frequent pathogens from wounds. The largest number of enterococci is isolated from urine.Conclusions. The etiological factor in the development of nosocomial GPSI in most cases is gram-negative microorganisms – A. baumanii (39.9 %), P. aeruginosa (20.7 %), K. pneumoniae (23.1 %). At the same time, in recent years, fungi have become increasingly important in the etiology of septic conditions.

Molecular epidemiology of methicillin-resistant Staphylococcus aureus in the Brazilian primary health care system

OBJECTIVE

To evaluate the molecular epidemiology and to georeference Staphylococcus aureus isolated from wounds and nares of patients seen at Basic Health Units (BHUs) of a Brazilian city.

METHODS

Observational, cross-sectional study conducted from 2010 to 2013. A total of 119 S. aureus strains isolated from the wounds and nares of 88 patients were studied. The isolates were characterised by identifying virulence genes encoding enterotoxins A-E, haemolysins α, β and δ, exfoliatins A, B and D, biofilm production, Panton-Valentine Leukocidin and toxic shock syndrome toxin 1, and by pulsed-field gel electrophoresis (PFGE), multilocus sequence and spa typing.

RESULTS

Eighteen methicillin-resistant Staphylococcus aureus (MRSA) (6 SCCmec type II and 12 SCCmec type IV) and 101 (85%) MSSA were identified. PFGE typing resulted in the formation of eight clusters, with STs 1, 5, 8, 30, 188, 1176 and 1635 and spa type t002 being the predominant types among MSSA. The 18 MRSA belonged to STs 5, 8 and 1176 and spa types t002 and t062.

CONCLUSION

The results demonstrate widespread dissemination of MSSA and MRSA clones carrying haemolysin, biofilm and toxin genes. Kernel density estimation revealed the highest density of S. aureus in the 4, 5 and 8 BHUs.

First report on MRSA CC398 recovered from wild boars in the north of Portugal. Are we facing a problem?

The aim of the present study was to evaluate the resistance of Staphylococcus aureus recovered from wild boars, to analyze their genetic lineages, and to investigate the susceptibility to oxacillin. Samples from mouth and nose of 45 wild boars (Sus scrofa) were collected during hunt activity from November 2012 to January 2013 in the North of Portugal. S. aureus isolates were recovered from 30 of these samples (33%); one isolate/sample was further studied. The susceptibility of the isolates was tested by disk-diffusion test against 14 antimicrobial agents and minimal inhibitory concentration was used to test oxacillin according to EUCAST guidelines. The genetic lineages of S. aureus were characterized by agr-typing, spa-typing and MLST. From the 30 isolates, 18 S. aureus were susceptible to all antibiotics tested and 7 presented resistance to one or more of the following antibiotics: penicillin (n=3), oxacillin (n=4), cefoxitin (n=1), clindamycin (n=2), gentamicin (n=1), fusidic acid (n=1), ciprofloxacin (n=2), tetracycline (n=1) and linezolid (n=1). One MRSA CC398 (spa-type t899) isolate was detected (oxacillin MIC=32mg/L and mecA-positive), which presented resistance to penicillin, tetracycline, and ciprofloxacin and contained the genes of immune evasion cluster (IEC) system (type B). The 29 methicillin-susceptible isolates were typed as ST1 (t1533), ST133 (t3583), ST1643 (t10712), ST2328 (t3750) and the new STs (3220, 3222, 3223, 3224) associated to new spa-types t14311 and t14312. The agr-types I, II, III and IV were identified. It is a matter of concern when MRSA and some specific lineages of S. aureus are taken as commensal habitants of the skin and nose of wild animals and are characterized with resistance to various antimicrobial agents in clinical use.

Epidemiology of Oral and Maxillofacial Infections

Dental caries and periodontal disease are the most common dental infections and are constantly increasing worldwide. Distribution, occurrence of dental caries, gingivitis, periodontitis, odontogenic infections, antibiotic resistance, oral mucosal infections, and microbe-related oral cancer are important to understand the public impact and methods of controlling such disease. Distribution of human papilloma virus and human immunodeficiency virus -related oral cancers in the US population is presented.

Genotyping of Methicillin Resistant Staphylococcus aureus Strains Isolated from Hospitalized Children

Community associated methicillin resistant Staphylococcus aureus (CA-MRSA) is an emerging pathogen increasingly reported to cause skin and soft tissue infections for children. The emergence of highly virulencet CA-MRSA strains in the immunodeficiency of young children seemed to be the basic explanation of the increased incidence of CA-MRSA infections among this population. The subjects of this study were 8 patients hospitalized in the Pediatric Department at the University Hospital of Monastir. The patients were young children (aged from 12 days to 18 months) who were suffering from MRSA skin infections; two of them had the infections within 72 h of their admission. The isolates were classified as community isolates as they all carried the staphylococcal cassette chromosome mec (SCCmec) IV and pvl genes. Epidemiological techniques, pulsed-field gel electrophoresis (PFGE) and multilocus sequence typing (MLST), were applied to investigate CA-MRSA strains. Analysis of molecular data revealed that MRSA strains were related according to PFGE patterns and they belonged to a single clone ST80. Antimicrobial susceptibility tests showed that all strains were resistant to kanamycin and 2 strains were resistant to erythromycin.

Antimicrobial resistance determinants in Staphylococcus spp. recovered from birds of prey in Portugal

Antibiotic resistance among wild animals represent an emerging public health concern. The objective of this study was to analyze the staphylococcal nasal microbiota in birds of prey and their content in antimicrobial resistance determinants. Nasal samples from 16 birds of prey were collected, swabs were dipped and incubated into BHI broth [6.5% NaCl] and later seeded on manitol salt agar and oxacillin-resistance screening agar base media. Staphylococcal colonies were isolated from both media and were identified by biochemical and molecular methods. Susceptibility testing to 18 antimicrobial agents was performed by disk-diffusion method. Six of the 16 tested animals carried staphylococci (37.5%) and 7 isolates of the following species were recovered: Staphylococcus aureus, Staphylococcus epidermidis, Staphylococcus saprophyticus, Staphylococcus sciuri rodentium, Staphylococcus cohnii urealitycum, and Staphylococcus gallinarum. The S. aureus isolate was penicillin-resistant (with blaZ gene) but methicillin-susceptible and was ascribed to spa-type t012, sequence-type ST30 and agr-type III. The S. epidermidis isolate carried blaZ, mecA, mrs(A/B), mphC, tet(K), drfA, and fusC genes, ica operon, and was typed as ST35. The genes ant6'-Ia, tet(K), tet(L), dfrG, cat221, cat194, and cat223 were detected in S. saprophyticus or S. gallinarum isolates. Birds of prey seem to be a natural reservoir of S. aureus and coagulase-negative staphylococci resistant to multiple antibiotics. Due to the convergence between habitats, the contact between wildlife, other animals and humans is now more common and this involves an increased possibility of interchange of these microorganisms in the different ecosystems.

Skin and soft tissue infections

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

Enlarged neck lymph nodes in children

Pediatric cervical lymphadenopathy is a challenging medical condition for the patient, family, and physician. There are a wide variety of causes for cervical lymphadenopathy and an understanding of these causes is paramount in determining the most appropriate workup and management. A thorough history and physical examination are important in narrowing the differential diagnosis. Diagnostic studies and imaging studies play an important role as well. This article reviews the common causes of lymphadenopathy, and presents a methodical approach to a patient with cervical lymphadenopathy.

Methicillin-Resistant Staphylococcus aureus Infections in Human Immunodeficiency Virus-Infected Children and Adolescents

Background. Methicillin-resistant Staphylococcus aureus (MRSA) infection incidence has increased in healthy US children. Our objective was to evaluate MRSA incidence and correlates in HIV-infected youth. Methods. The CDC-sponsored LEGACY study is a US multicenter chart abstraction study of HIV-infected youth. We identified MRSA infections among participants with ≥1 visit during 2006. We used bivariate and multivariable analyses to compare sociodemographic and HIV clinical factors between MRSA cases and noncases. Results. Fourteen MRSA infections (1 invasive, 12 soft tissue, 1 indeterminate) occurred among 1,813 subjects (11.1 infections/1,000 patient-years (PY), 95% CI: 11.06–11.14). Most (86%) isolates were clindamycin susceptible. Compared with noncases, MRSA cases were more likely older (17 versus 14 years), black (100% versus 69%), behaviorally HIV infected (43% versus 17%), and in Maryland (43% versus 7%) and had viral loads (VL) >1000 copies/mL (86% versus 51%) and lower mean CD4% (18% versus 27%) (all P < 0.05). In multivariate analysis, independent risk factors were Maryland care site (adjusted odds ratio (aOR) = 9.0), VL >1000 copies/mL (aOR = 5.9), and black race (aOR undefined). Conclusions. MRSA occurred at a rate of 11.1 infections/1,000 PY in HIV-infected youth but invasive disease was uncommon. Geographic location, black race, and increased VL, but not immunosuppression, were independently associated with MRSA risk.

Spread of epidemic MRSA-ST5-IV clone encoding PVL as a major cause of community onset staphylococcal infections in Argentinean children

BACKGROUND

Community-associated methicillin-resistant Staphylococcus aureus-(CA-MRSA) strains have emerged in Argentina. We investigated the clinical and molecular evolution of community-onset MRSA infections (CO-MRSA) in children of Córdoba, Argentina, 2005-2008. Additionally, data from 2007 were compared with the epidemiology of these infections in other regions of the country.

METHODOLOGY/PRINCIPAL FINDINGS

Two datasets were used: i) lab-based prospective surveillance of CA-MRSA isolates from 3 Córdoba pediatric hospitals-(CBAH1-H3) in 2007-2008 (compared to previously published data of 2005) and ii) a sampling of CO-MRSA from a study involving both, healthcare-associated community-onset-(HACO) infections in children with risk-factors for healthcare-associated infections-(HRFs), and CA-MRSA infections in patients without HRFs detected in multiple centers of Argentina in 2007. Molecular typing was performed on the CA-MRSA-(n: 99) isolates from the CBAH1-H3-dataset and on the HACO-MRSA-(n: 51) and CA-MRSA-(n: 213) isolates from other regions. Between 2005-2008, the annual proportion of CA-MRSA/CA-S. aureus in Córdoba hospitals increased from 25% to 49%, P<0.01. Total CA-MRSA infections increased 3.6 fold-(5.1 to 18.6 cases/100,000 annual-visits, P<0.0001), associated with an important increase of invasive CA-MRSA infections-(8.5 fold). In all regions analyzed, a single genotype prevailed in both CA-MRSA (82%) and HACO-MRSA(57%), which showed pulsed-field-gel electrophoresis-(PFGE)-type-"I", sequence-type-5-(ST5), SCCmec-type-IVa, spa-t311, and was positive for PVL. The second clone, pulsotype-N/ST30/CC30/SCCmecIVc/t019/PVL(+), accounted for 11.5% of total CA-MRSA infections. Importantly, the first 4 isolates of Argentina belonging to South American-USA300 clone-(USA300/ST8/CC8/SCCmecIVc/t008/PVL(+)/ACME(-)) were detected. We also demonstrated that a HA-MRSA clone-(pulsotype-C/ST100/CC5) caused 2% and 10% of CA-MRSA and HACO-MRSA infections respectively and was associated with a SCCmec type closely related to SCCmecIV(2B&5).

CONCLUSIONS/SIGNIFICANCE

The dissemination of epidemic MRSA clone, ST5-IV-PVL(+) was the main cause of increasing staphylococcal community-onset infections in Argentinean children (2003-2008), conversely to other countries. The predominance of this clone, which has capacity to express the h-VISA phenotype, in healthcare-associated community-onset cases suggests that it has infiltrated into hospital-settings.

Usefulness of the restriction-modification test plus staphylococcal cassette chromosome mec types and Panton-Valentine leukocidin encoding phages to identify Staphylococcus aureus methicillin-resistant clones

We studied the usefulness of the restriction-modification (RM) test, staphylococcal cassette chromosome (SCC) mec types, and Panton-Valentine leukocidin (PVL)-encoding phages to identify Staphylococcus aureus methicillin-resistant lineages and to differentiate clones that belong to the same lineage. A total of 108 methicillin-resistant S. aureus (MRSA) strains were characterized by pulsed-field gel electrophoresis (PFGE)--multi-locus sequence typing (MLST)--spa-typing. The RM correctly identified the lineages CC5, CC8, CC30, and CC398, but not CC25 and CC72. The SCCmec and RM combined analysis allowed differentiation between MLST types within the same lineage. Only 5 MRSA strains were PVL-positive. Four PVL-positive USA300 isolates carried elongated-head type PVL-encoding phages, while the sequence type (ST)-30 strain carried an icosahedral-head phage. The combination of the RM test method, SCCmec types, and PVL phage identification could be useful for MRSA typing purposes.

Antibiotic therapy in neonatal and pediatric septic shock

Severe sepsis accounts for nearly 4,500 deaths (mortality rate 10%), and is responsible for nearly $2 billion annual healthcare expenditure in the United States. Early and speedy treatment of critically ill septic patients can halt or reduce the likelihood of physiologic progression to multi-system organ failure. A cornerstone of this therapeutic strategy is antibiotic administration. In this review, we discuss the empirical treatment strategies for the treatment of early and late neonatal sepsis, along with pediatric sepsis. Furthermore, we discuss the rationale that underlies the adoption of such treatment strategies. The present article also discusses the emergence of multi-drug organisms as the causative agents for sepsis, i.e. methicillin-resistant Staphylococcus aureus (MRSA), resistant enterococci and Klebsiella pneumoniae carbapenemases (KPC).

Methicillin-resistant Staphylococcus aureus colonization and risk of subsequent infection in critically ill children: importance of preventing nosocomial methicillin-resistant Staphylococcus aureus transmission

BACKGROUND

Methicillin-resistant Staphylococcus aureus (MRSA) colonization is a predictor of subsequent infection in hospitalized adults. The risk of subsequent MRSA infections in hospitalized children colonized with MRSA is unknown.

METHODS

Children admitted to an academic medical center's pediatric intensive care unit between March 2007 and March 2010 were included in the study. Anterior naris swabs were cultured to identify children with MRSA colonization at admission. Laboratory databases were queried and National Healthcare Safety Network definitions applied to identify patients with MRSA infections during their hospitalization or after discharge.

RESULTS

The MRSA admission prevalence among 3140 children was 4.9%. Overall, 56 children (1.8%) developed an MRSA infection, including 13 (8.5%) colonized on admission and 43 (1.4%) not colonized on admission (relative risk [RR], 5.9; 95% confidence interval [CI], 3.4-10.1). Of those, 10 children (0.3%) developed an MRSA infection during their hospitalization, including 3 of 153 children (1.9%) colonized on admission and 7 of 2987 children (0.2%) not colonized on admission (RR, 8.4; 95% CI, 2.7-25.8). African-Americans and those with public health insurance were more likely to get a subsequent infection (P < .01 and P = .03, respectively). We found that 15 children acquired MRSA colonization in the pediatric intensive care unit, and 7 (47%) developed a subsequent MRSA infection.

CONCLUSIONS

MRSA colonization is a risk factor for subsequent MRSA infection in children. Although MRSA colonized children may have lower risks of subsequent infection than adults, children who acquire MRSA in the hospital have similarly high rates of infection. Preventing transmission of MRSA in hospitalized children should remain a priority.

Emergency department treatment failures for skin infections in the era of community-acquired methicillin-resistant Staphylococcus aureus

BACKGROUND

Despite rapidly increasing incidence of skin and soft tissue infections (SSTIs) presenting to emergency departments (EDs), outcome data for these infections are limited.

METHODS

This is a retrospective cohort study of children with culture-positive SSTI, managed as outpatients from a large pediatric ED in the year 2006. The primary outcome was treatment failure, defined as presence of 1 or more of the following: (1) change in antibiotic owing to poor clinical response, (2) subsequent incision and drainage, or (3) hospitalization. Demographics, isolated pathogens, and therapeutics were also assessed. To accurately capture the outcome of interest, only children who are observed in the hospital-based primary care network were included.

RESULTS

Among 148 eligible subjects, there were 158 SSTIs including 131 abscesses, 19 folliculitis, and 8 cellulitis. Mean age was 9.1 ± 6.2 years, 41.2% were male, and 94.6% were African American. Methicillin-resistant Staphylococcus aureus (MRSA) was isolated in 66%, methicillin-sensitive S. aureus (MSSA) in 21%, and others in 13%. Outcome data were available for 144 subjects (97.2%). Emergency department treatment failure rate was 7.6% (95% confidence interval, 3.3%-12.0%); 10 of 11 failures were abscesses. Only S. aureus produced treatment failure and occurred in 13.3% of MSSA and 6.4% MRSA infections (odds ratio, 1.9; 95% CI, 0.5-7.1). An antibiotic to which the organism was sensitive was prescribed for 9 (81.8%) of 11 treatment failures and did not differ between MRSA and MSSA; appropriate antibiotics were used in 91.5% of treatment successes.

CONCLUSIONS

The rate of ED treatment failure for SSTI is low and is more likely to occur with S. aureus infection, irrespective of methicillin resistance or appropriate antibiotic therapy.

Antibiotic susceptibility patterns of Staphylococcus aureus isolates from Australian children

AIM

Staphylococcus aureus is an important cause of serious illness in children. Antibiotic resistance is an international problem and affects initial antibiotic choice. We aimed to describe susceptibility patterns of S. aureus isolates from Australian children to inform optimal empiric treatment of staphylococcal infections in this population.

METHODS

We analysed susceptibility data for all S. aureus isolates from children at Australian tertiary paediatric hospitals in 2006. Susceptibility rates were compared between hospitals and states, and with published studies of S. aureus isolates from Australian adults.

RESULTS

Overall, the proportion of methicillin-resistant S. aureus (MRSA) in Australian children was low (9.8%), and in each state it was less than for the comparable adult population. There were significant differences in susceptibility patterns between different states. Most MRSA isolates were susceptible to clindamycin (73%) and all isolates were reported as susceptible to vancomycin. Susceptibility patterns for isolates from bacteraemic patients were similar to those for isolates from all patients.

CONCLUSIONS

These data support current Australian recommendations for the use of flucloxacillin or a first-generation cephalosporin as initial treatment of non-life-threatening staphylococcal infections. However, broad spectrum antibiotic therapy including agents that are effective against MRSA should be considered for more serious infections. Appropriate specimens should be collected for susceptibility testing to enable directed treatment for MRSA and other resistant organisms. This study highlights the importance of using local, age-specific data in planning antibiotic treatment guidelines, as results vary substantially from city to city and between adults and children.

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

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

Diagnosis and management of community-associated MRSA infections in children

The history of antibiotic resistance in Staphylococcus aureus spans more than half a century. Methicillin-resistant S. aureus (MRSA) has emerged as an almost ubiquitous pathogen in both the community and hospital settings. The predominant clone responsible for community-associated MRSA, USA300, is a highly successful pathogen, as demonstrated by its rapid global spread and associated morbidity and mortality. The management of MRSA infections in pediatric patients is complicated by the limited number of effective antibiotics that have been well-studied in children. The gold standard antimicrobial, vancomycin, has several shortcomings that have prompted the development of newer agents for the treatment of MRSA disease. Moreover, the emergence of vancomycin-intermediate or -resistant S. aureus, while uncommon, portends a potential new era of resistance that will require research and development of the next generation of antibiotics that act by novel mechanisms.

Community-associated methicillin-resistant Staphylococcus aureus strains in pediatric intensive care unit

Virulent community-associated methicillin-resistant Staphylococcus-aureus (CA-MRSA) strains have spread rapidly in the United States. To characterize the degree to which CA-MRSA strains are imported into and transmitted in pediatric intensive care units (PICU), we performed a retrospective study of children admitted to The Johns Hopkins Hospital PICU, March 1, 2007-May 31, 2008. We found that 72 (6%) of 1,674 PICU patients were colonized with MRSA. MRSA-colonized patients were more likely to be younger (median age 3 years vs. 5 years; p = 0.02) and African American (p<0.001) and to have been hospitalized within 12 months (p<0.001) than were noncolonized patients. MRSA isolates from 66 (92%) colonized patients were fingerprinted; 40 (61%) were genotypically CA-MRSA strains. CA-MRSA strains were isolated from 50% of patients who became colonized with MRSA and caused the only hospital-acquired MRSA catheter-associated bloodstream infection in the cohort. Epidemic CA-MRSA strains are becoming endemic to PICUs, can be transmitted to hospitalized children, and can cause invasive hospital-acquired infections. Further appraisal of MRSA control is needed.

Emergency management of pediatric skin and soft tissue infections in the community-associated methicillin-resistant Staphylococcus aureus era

OBJECTIVES

Skin and soft tissue infections (SSTIs) are increasing in incidence, yet there is no consensus regarding management of these infections in the era of community-associated methicillin-resistant Staphylococcus aureus (CA-MRSA). This study sought to describe current pediatric emergency physician (PEP) management of commonly presenting skin infections.

METHODS

This was a cross-sectional survey of subscribers to the American Academy of Pediatrics Section on Emergency Medicine (AAP SoEM) list-serv. Enrollment occurred via the list-serv over a 3-month period. Vignettes of equivocal SSTI, cellulitis, and skin abscess were presented to participants, and knowledge, diagnostic, and therapeutic approaches were assessed.

RESULTS

In total, 366 of 606 (60.3%) list-serv members responded. The mean (+/- standard deviation [SD]) duration of practice was 13.6 (+/-7.9) years, and 88.6% practiced in a pediatric emergency department. Most respondents (72.7%) preferred clinical diagnosis alone for equivocal SSTI, as opposed to invasive or imaging modalities. For outpatient cellulitis, PEPs selected clindamycin (30.6%), trimethoprim-sulfa (27.0%), and first-generation cephalosporins (22.7%); methicillin-sensitive S. aureus (MSSA) was routinely covered, but many regimens failed to cover CA-MRSA (32.5%) or group A streptococcus (27.0%). For skin abscesses, spontaneous discharge (67.5%) was rated the most important factor in electing to perform a drainage procedure; fever (19.9%) and patient age (13.1%) were the lowest. PEPs elected to prescribe trimethoprim-sulfamethoxazole (TMP-Sx; 50.0%) or clindamycin (32.7%) after drainage; only 5% selected CA-MRSA-inactive agents. All PEPs suspected CA-MRSA as the etiology of skin abscesses, and many attributed sepsis (22.1%) and invasive pneumonia (20.5%) to CA-MRSA, as opposed to MSSA. However, 23.9% remained unaware of local CA-MRSA prevalence for even common infections.

CONCLUSIONS

Practice variation exists among PEPs for management of SSTI. These results can be used to measure changes in SSTI practices as standardized approaches are delineated.

Incidence of invasive community-onset Staphylococcus aureus infections in children in Central New York

We determined the incidence of invasive community-onset Staphylococcus aureus infections, clinical characteristics, and antibiotic susceptibilities in 128 hospitalized children in central New York. The prevalence of invasive S aureus infections in our institution remained <1% between 1996 and 2006, although the proportion of methicillin-resistant S aureus infections significantly increased.

Pediatric and neonatal Staphylococcus aureus bacteremia: epidemiology, risk factors, and outcome

OBJECTIVE

To evaluate the impact of methicillin-resistant Staphylococcus aureus on the prevalence of S. aureus bloodstream infection among children.

METHODS

Retrospective analysis of demographic data, risk factors for infection, and clinical outcomes for children (age, less than 18 years) with S. aureus bacteremia hospitalized at a children's hospital during 2001-2006.

RESULTS

We identified 164 episodes of S. aureus bacteremia among 151 children. The prevalence of bacteremia due to methicillin-susceptible S. aureus during 2001-2003 was approximately the same as that during 2004-2006 (29 and 30 cases, respectively, per 10,000 hospitalized children [hereafter, "per 10,000 hospitalizations"]), but the prevalence of bacteremia due to methicillin-resistant S. aureus increased from 4 to 11 cases, respectively, per 10,000 hospitalizations (P=.015). A total of 48% of infections involved children who had S. aureus-positive blood cultures less than 3 days after hospital admission. Seventy-four percent of these children had a preexisting comorbidity. When the prevalence of S. aureus bacteremia was stratified by race, sex, or age, neonates hospitalized at birth and Hispanic children had significantly reduced risks of infection. Children younger than 1 year of age (excluding neonates hospitalized at birth) had an increased prevalence of hospital-onset S. aureus bacteremia. There was a disproportionate increase in the risk of S. aureus bacteremia for each additional week of hospitalization among children with hospital-onset S. aureus bacteremia. Children with methicillin-resistant S. aureus bacteremia had a longer hospital stay, were transferred to another facility at a greater rate than they were discharged home, and had a greater mortality rate, compared with children with methicillin-susceptible S. aureus bacteremia.

CONCLUSION

This study documents the prevalence of S. aureus bacteremia among children with a high risk for acquiring this infection, and it describes populations of children who are at higher risk for bacteremia due to either methicillin-susceptible or methicillin-resistant S. aureus. Methods to improve prevention of S. aureus bacteremia are needed for children with healthcare-associated risk factors for S. aureus bacteremia.

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

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

Trimethoprim-sulfamethoxazole for methicillin-resistant Staphylococcus aureus: a forgotten alternative?

Methicillin-resistant Staphylococcus aureus (MRSA) is a growing infectious concern, mainly in the context of its rapid adaptation to novel antibiotic options for its treatment and the growing morbidity, mortality, and healthcare costs associated with its emergence. the authors sought to investigate whether an older antibiotic, such as trimethoprim-sulfamethoxazole (SXT), may have a role in treating MRSA-related infections, according to the available literature on the subject. The authors reviewed literature data on: resistance of MRSA to SXT worldwide in recent years, efficacy of SXT for MRSA decolonization or prophylaxis from MRSA infections, and clinical therapeutic efficacy of SXT in treating mild or severe community-acquired or hospital-acquired MRSA infections. Resistance varies worldwide, in general being low in the industrialized world and higher in developing countries. SXT is one of the numerous understudied options for MRSA decolonization and is growingly recognized as potentially effective in preventing MRSA infections in certain settings. Limited data on its therapeutic efficacy are encouraging, at least for mild, community-acquired infections. SXT may represent a cost-effective alternative weapon against MRSA. Its utility against this increasingly threatening pathogen need clarification through further clinical trials.

Cutaneous methicillin-resistant Staphylococcus aureus in a suburban community hospital pediatric emergency department

BACKGROUND

Studies on methicillin-resistant Staphylococcus aureus (MRSA) infections have typically focused on pediatric and adult populations at urban tertiary care hospitals. Limited data exist on MRSA rates in skin and soft tissue infections (SSTI) in suburban community hospital pediatric emergency departments (PED).

OBJECTIVES

To describe the prevalence of MRSA in SSTIs in a contemporary suburban community hospital PED population.

METHODS

Patients 0-21 years old with SSTI wound cultures who were seen at our PED from 2003-2007 were studied. Data analyzed included type of infection (abscess vs. non-abscess), site of infection, and culture results. Chi-squared and t-tests were used as appropriate; p < 0.05 was considered significant.

RESULTS

During the study period, 204 cultures were obtained for SSTIs, 11 of which were contaminants. The subjects had a mean age of 12.9 years (SD 6.8 years); 60% were male. The prevalence of MRSA was 27%; MRSA was present in 30% of abscesses vs. 2.2% of non-abscess SSTI (p < 0.005). By year, the prevalence of MRSA was 10% in 2003, 31% in 2004, 33% in 2005, 31% in 2006, and 29% in 2007. No differences between MRSA and non-MRSA infections were present for gender, age, or site of infection.

CONCLUSIONS

At our suburban community hospital pediatric ED, MRSA was present in 30% of all SSTI wound cultures; MRSA was unlikely with non-abscess SSTI. Our overall MRSA prevalence data among SSTIs are consistent with previously published reports in pediatric ED populations but may be less than those reported in the adult literature.

Empiric antimicrobial therapy for pediatric skin and soft-tissue infections in the era of methicillin-resistant Staphylococcus aureus

OBJECTIVE

The goal was to compare the clinical effectiveness of monotherapy with beta-lactams, clindamycin, or trimethoprim-sulfamethoxazole in the outpatient management of nondrained noncultured skin and soft-tissue infections (SSTIs), in a methicillin-resistant Staphylococcus aureus (MRSA)-endemic region.

METHODS

A retrospective, nested, case-control trial was conducted with a cohort of patients from 5 urban pediatric practices in a community-acquired MRSA-endemic region. All subjects were treated as outpatients with oral monotherapy for nondrained noncultured SSTIs between January 2004 and March 2007. The primary outcome was treatment failure, defined as a drainage procedure, hospitalization, change in antibiotic, or second antibiotic prescription within 28 days.

RESULTS

Of 2096 children with nondrained noncultured SSTIs, 104 (5.0%) were identified as experiencing treatment failure and were matched to 480 control subjects. Compared with beta-lactam therapy, clindamycin was equally effective but trimethoprim-sulfamethoxazole was associated with an increased risk of failure. Other factors independently associated with failure included initial treatment in the emergency department, presence or history of fever, and presence of either induration or a small abscess.

CONCLUSIONS

Compared with beta-lactams, clindamycin monotherapy conferred no benefit, whereas trimethoprim-sulfamethoxazole was associated with an increased risk of treatment failure in a cohort of children with nondrained noncultured SSTIs who were treated as outpatients. Even in regions with endemic community-acquired MRSA, beta-lactams may still be appropriate, first-line, empiric therapy for children presenting with these infections.

Staphylococcus epidermidis strains isolated from breast milk of women suffering infectious mastitis: potential virulence traits and resistance to antibiotics

Background

Although Staphylococcus aureus is considered the main etiological agent of infectious mastitis, recent studies have suggested that coagulase-negative staphylococci (CNS) may also play an important role in such infections. The aims of this work were to isolate staphylococci from milk of women with lactational mastitis, to select and characterize the CNS isolates, and to compare such properties with those displayed by CNS strains isolated from milk of healthy women.

Results

The milk of 30 women was collected and bacterial growth was noted in 27 of them, of which Staphylococcus epidermidis was isolated from 26 patients and S. aureus from 8. Among the 270 staphylococcal isolates recovered from milk of women with mastitis, 200 were identified as Staphylococcus epidermidis by phenotypic assays, species-specific PCR and PCR sequencing. They were typified by pulsed field gel electrophoresis (PFGE) genotyping. The PFGE profiles of the S. epidermidis strains were compared with those of 105 isolates from milk of healthy women. A representative of the 76 different PFGE profiles was selected to study the incidence of virulence factors and antibiotic resistance. The number of strains that contained the biofilm-related icaD gene and that showed resistance to oxacillin, erythromycin, clindamycin and mupirocin was significantly higher among the strains isolated from mastitic milk.

Conclusion

S. epidermidis may be a frequent but largely underrated cause of infectious mastitis in lactating women. The resistance to diverse antibiotics and a higher ability to form biofilms found among the strains isolated from milk of women suffering mastitis may explain the chronic and/or recurrent nature of this infectious condition.

Current knowledge of methicillin-resistant Staphylococcus aureus and community-associated methicillin-resistant Staphylococcus aureus

BACKGROUND

Bacterial strains that are oxacillin and methicillin-resistant, historically termed methicillin-resistant Staphylococcus aureus (MRSA) are resistant to all beta-lactam agents, including cephalosporins and carbapenems. MRSA are pathogenic and have a number of virulence factors that enable them to result in disease. They are transmissible and important causes of nosocomial infections worldwide. An MRSA outbreak can occur when one strain is transmitted to other patients or through close contacts of infected persons in the community. Hospital-associated MRSA (HA-MRSA) isolates are also frequent causes of healthcare-associated bloodstream and catheter-related infections. Community-associated MRSA (CA-MRSA) isolates are often only resistant to beta-lactam agents and erythromycin but they are an emerging cause of community-associated infections, especially skin and soft tissue infections (SSTI) and necrotizing pneumonia.

METHODS

Current possibilities for detecting MRSA strains in the laboratory are reviewed and discussed in the context of the recent literature.

RESULTS AND CONCLUSION

The active surveillance and prevention of MRSA occurrence and spreading in hospitals are discussed in the context of recent literature.

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.

Antibiotic selection for purulent skin and soft-tissue infections in ambulatory care: a decision-analytic approach

OBJECTIVE

Community-associated methicillin-resistant Staphylococcus aureus (CA-MRSA) has caused a nationwide epidemic of skin and soft-tissue infections in ambulatory pediatrics. Antibiotic treatment recommendations suggest incorporating local epidemiology for the prevalence of CA-MRSA. We sought to identify the antibiotic strategy with the highest probability of activity and to identify threshold values for epidemiologic variables including bacterial prevalence and antibiotic resistance.

METHODS

We used decision analysis to evaluate 3 empiric antibiotic strategies: clindamycin, trimethoprim/sulfamethoxazole (T/S), and cephalexin. We calculated the probability of activity against the bacteria causing the infection (CA-MRSA, methicillin-sensitive S. aureus and group A Streptococcus [GAS]) by incorporating estimates of prevalence and antibiotic resistance to determine the optimal strategy. Sensitivity analysis was used to identify thresholds for prevalence and antibiotic resistance where 2 strategies were equal.

RESULTS

Clindamycin (0.95) and T/S (0.89) had substantially higher probability of activity than cephalexin (0.28) using baseline estimates for bacterial prevalence and antibiotic resistance. Cephalexin was the optimal antibiotic only when CA-MRSA prevalence was <10%. The probability of activity for clindamycin and T/S was highly sensitive to changes in the values for bacterial prevalence (both CA-MRSA and GAS) and CA-MRSA resistance to clindamycin.

CONCLUSIONS

Empiric treatment of skin and soft-tissue infections with either clindamycin or T/S maximizes the probability that the antibiotic will be active when CA-MRSA prevalence is >10%. Deciding between T/S and clindamycin requires consideration of antibiotic resistance and prevalence of GAS. This model can be customized to local communities and illustrates the importance of ongoing epidemiologic surveillance in primary care settings.

The role of molecular methods in the prevention of nosocomial methicillin-resistant Staphylococcus aureus clusters in cancer patients

In 2002, an increased incidence of nosocomial methicillin-resistant Staphylococcus aureus (MRSA) in our institution triggered a conventional investigation that failed to identify a common source. Molecular typing of the 70 nosocomial MRSA isolates obtained identified a predominant health care-associated clone A in the first trimester. Aggressive infection control measures led to a significant decrease in the number of isolates per 10,000 hospital days between the first trimester and the last 2 trimesters of 2003 (6.4 vs 3.8; P = .04). This was attributed to a decrease in clone A: SCCmec II, USA100, PVL gene-negative (2.3 per 10.000 patient-days vs 0.1 per 10,000 patient-days; P = .004). However, in 2003, 23% of the nosocomial isolates were SCCmec IV, USA300, PVL gene-positive. At that time, molecular methods allowed the detection and prevention of a nosocomial MRSA outbreak caused by a health care-associated clone; however, the community strains (SCCmec IV) have become a frequent cause of nosocomial infection in our institution.

Community-associated Staphylococcus aureus infections and nasal carriage among children: molecular microbial data and clinical characteristics

An increasing number of infections caused by community-associated methicillin-resistant Staphylococcus aureus (CA-MRSA) carrying the Panton-Valentine leukocidin (PVL) genes was recently identified in Greece. In the present study, 170 patients with S. aureus infections and 123 uninfected children (<15 years old) who had been tested for nasal carriage were evaluated during a 2-year period. The MecA, PVL and superantigen family genes, and MRSA clones, were investigated by molecular methods. Sites of infection and laboratory findings for patients were recorded. The results were compared and statistically analysed. Among 123 uninfected children 73 (59%) carried S. aureus, including four MRSA strains. Of these, three MRSA and three methicillin-sensitive S. aureus (MSSA) strains were PVL-positive (p <0.0001). Ninety-six patients (96/170) exhibited skin and soft-tissue infections (SSTIs), and 74 exhibited invasive infections. The incidence of staphylococcal infections increased during July to September each year. In total, 110 S. aureus isolates were PVL-positive (81 from SSTIs and 29 from invasive infections, p <0.0001). Ninety-nine out of 106 MRSA (93%) isolates from 170 patients carried the PVL genes (p <0.0001); 97 belonged to the clonal complex CC80. Leukocyte and polymorphonuclear cell counts were higher among children with MRSA infections (p <0.005). MSSA predominated among patients with invasive infections (43/74), and carried mainly genes of the superantigen family. Children <5 years of age showed a higher risk of MRSA infection. The present study demonstrates that infections due to PVL-positive CA-MRSA spread easily among children, and SSTIs can lead to invasive infections. Nasal colonization may be an additional factor contributing to the emergence of CA-MRSA.

Methicillin-resistant Staphylococcus aureus colonization in children with atopic dermatitis

Children with atopic dermatitis are more frequently colonized with Staphylococcus aureus than children without atopic dermatitis. However, little epidemiological data exist regarding the prevalence of methicillin-resistant S. aureus among children with atopic dermatitis. Recent studies have revealed an increasing prevalence of community-associated methicillin-resistant S. aureus among patients presenting to hospitals with serious bacterial infections, particularly those with cutaneous and soft tissue infections. As many atopic dermatitis patients are treated empirically with antibiotics for secondary skin infections, an understanding of the epidemiology of bacterial colonization and superinfection is essential for directing proper treatment in the atopic patient population. This study investigates the prevalence of risk factors for community-associated, methicillin-resistant S. aureus colonization among pediatric atopic dermatitis patients encountered at an academic pediatric dermatology clinic. An observational cross-sectional study was conducted at the Children's Hospital of Philadelphia in which 54 patients previously diagnosed with atopic dermatitis were enrolled. A detailed patient questionnaire, a complete cutaneous examination, and an evaluation of eczema severity according to the Eczema Area and Severity Index were completed at the time of enrollment. Bacterial cultures from the skin and nares were obtained to determine the frequency of colonization with either methicillin-sensitive S. aureus or methicillin-resistant S. aureus. Although most atopic dermatitis patients studied were colonized with S. aureus (43/54 [80%]), methicillin-resistant S. aureus was isolated from only seven atopic dermatitis patients (7/43 [16%]). Patients colonized with S. aureus were more likely to be male, to have been previously hospitalized, to have used a topical calcineurin inhibitor in combination with a topical steroid, and less likely to have used topical antibiotics. Bivariable analysis, however, revealed that only previous hospitalization was independently associated with an increased risk of methicillin-resistant S. aureus colonization. We observed that 80% of atopic dermatitis patients were colonized with S. aureus, and that of these patients, 16% of colonized patients were colonized with a methicillin-resistant strain. Methicillin-resistant S. aureus colonization was found to be significantly associated with previous hospitalization. Evidence also indicates that topical calcineurin inhibitors used in conjunction with topical steroids is associated with increased S. aureus colonization, while topical antibiotic use appears to decrease S. aureus colonization.

MRSA with progression from otitis media and sphenoid sinusitis to clival osteomyelitis, pachymeningitis and abducens nerve palsy in an immunocompetent 10-year-old patient

A previously healthy 10-year-old patient with headache, otalgia, and hearing loss was diagnosed with pachymeningitis and methicillin-resistant Staphylococcus aureus otitis media and bacteremia. Despite antimicrobial therapy, intracranial extension progressed, including clival osteomyelitis, sphenoid sinusitis, cavernous sinus inflammation and cranial nerve palsies, until the sphenoid sinus was drained. This case exemplifies an aggressive MRSA intracranial infection that advanced despite antibiotic therapy.

Community-associated CMRSA-10 (USA-300) is the predominant strain among methicillin-resistant Staphylococcus aureus strains causing skin and soft tissue infections in patients presenting to the emergency department of a Canadian tertiary care hospital

Community-associated methicillin-resistant Staphylococcus aureus (CA-MRSA) is an emerging pathogen first described among individuals with no contact with health care facilities. The purpose of this study was to determine the proportion of CA-MRSA, defined by pulsed field gel electrophoresis (PFGE), in MRSA skin and soft tissue infections presenting to the Emergency Department (ED). We also aimed to describe the laboratory and clinical characteristics of CA-MRSA infections. From June 1, 2001 to May 30, 2005, MRSA isolates from skin and soft tissue infections presenting to the ED were reviewed. They were characterized by antibiotic susceptibilities and PFGE, and the presence of staphylococcal cassette chromosome (SCC) mec type IVa and Panton-Valentine leukocidin (PVL) genes was assessed on representative isolates. The medical records were reviewed to define risk factors. There were 95 isolates available for analysis, of which 58 (61%) were CMRSA-10 (USA-300), the predominant clone from 2003 onward. All representative isolates (24%) tested in this group had PVL genes and SCCmec type IVa. Their antibiogram showed 100% susceptibility to trimethoprim-sulfamethoxazole, rifampin, and fusidic acid, and 79% to clindamycin. Clinical comparison of CMRSA-10 vs. hospital PFGE type strains showed 22% vs. 60%, respectively, for recent antibiotic use (p < 0.0001), 26% vs. 6%, respectively, for intravenous drug use (p < 0.05), and 57% vs. 6%, respectively, for soft tissue abscess (p < 0.001). CMRSA-10 is a major pathogen in skin and soft tissue abscesses in our ED. It has a characteristic susceptibility, and was associated with intravenous drug use, but not with recent antibiotic usage.

Update on the epidemiology and management of Staphylococcus aureus, including methicillin-resistant Staphylococcus aureus, in patients with cystic fibrosis

PURPOSE OF REVIEW

Staphylococcus aureus is one of the first and most common pathogens to be isolated from the respiratory tract of patients with cystic fibrosis. The prevalence of respiratory tract colonization/infection with both methicillin-susceptible and methicillin-resistant S. aureus has increased over the past decade. The clinical significance of colonization/infection with these pathogens is variable, leading to numerous therapeutic strategies: primary prophylaxis, eradication, treatment of cystic fiboris pulmonary exacerbations, and treatment of methicillin-resistant S. aureus.

RECENT FINDINGS

Studies have demonstrated increased prevalence of S. aureus in clinical laboratories that use selective media. Additionally, small colony variant S. aureus has been associated with persistent infection, co-infection with Pseudomonas aeruginosa, and frequent courses of antibiotics, but this phenotype may be difficult to identify in clinical laboratories. Increased prevalence of methicillin-resistant S. aureus has led to use of oral and inhaled antibiotics in attempts to eradicate this pathogen; these studies have yielded variable results.

SUMMARY

The epidemiology of S. aureus in cystic fibrosis has changed. Studies are needed to assess the clinical significance of the increased prevalence of both methicillin-susceptible and methicillin-resistant S. aureus, and whether primary prophylaxis or new treatment/eradication protocols are effective.

Prevalence of nasal colonization with methicillin-resistant Staphylococcus aureus (MRSA) in children a multicenter cross-sectional study

In this cross-sectional multicenter study, we determined the rate of nasal carriage of methicillin-resistant Staphylococcus aureus (MRSA) in children admitted to 9 training hospitals in Switzerland during 1 month. From 1337 patients, 1363 nasal swabs were obtained (mean age 6.1 years, median 4.7 years, interquartile range 1.3-10.4 years) and 562 (41.3%) grew S. aureus. Only one isolate was MRSA (0.18%) which encoded mecA and femA genes as well as SCCmec type IV, whereas Panton-Valentine leukocidin (PVL) was absent.

Pediatric community-acquired methicillin-resistant Staphylococcus aureus infection and colonization: trends and management

PURPOSE OF REVIEW

The scourge of community-acquired methicillin-resistant Staphylococcus aureus in pediatrics continues unabated. This review provides information on changes in epidemiology, therapeutic considerations, and measures to control the epidemic.

RECENT FINDINGS

The epidemiology and clinical manifestations of methicillin-resistant S. aureus have undergone important changes that pose challenges in recognition, diagnosis, and treatment for the pediatrician. Community-acquired methicillin-resistant S. aureus used to be predominantly associated with localized disease among previously healthy children; however, there are recent reports of more invasive and severe diseases with some fatalities. The antibiotic susceptibility pattern is also changing with some community-acquired methicillin-resistant S. aureus having resistance patterns indistinguishable from that of hospital-acquired methicillin-resistant S. aureus. Thus the choice of antibiotics is becoming even more challenging in pediatrics, with an already-limited armamentarium of antibiotics. The management of common skin diseases such as furunculosis and boils now requires close collaboration between the general pediatrician and the infectious diseases specialist.

SUMMARY

As the burden of community-acquired methicillin-resistant S. aureus disease continues to increase, pediatricians must have a high index of suspicion and must institute appropriate antimicrobial therapy based on community or regional antibiotic susceptibility of community-acquired methicillin-resistant S. aureus. There is an urgent need for effective infection control programs, including active surveillance components, to help curb the epidemic.

Emerging Options for Treatment of Invasive, Multidrug-ResistantStaphylococcus aureusInfections

Limited established treatment options exist for the treatment of serious, invasive infections caused by multidrug-resistant Staphylococcus aureus, most notably nosocomially acquired methicillin-resistant S. aureus (MRSA). Although vancomycin represents the gold standard for therapy of such invasive infections, reports of increasing in vitro resistance to vancomycin, combined with reports of clinical failures (with this and other antistaphylococcal agents), underscore the need for alternative therapies. Older agents with favorable in vitro activity available in both oral and intravenous dose forms include trimethoprim-sulfamethoxazole and clindamycin. Limited clinical data exist to support their routine use as initial therapy in the treatment of invasive disease. However, these and other options (e.g., tetracyclines) are being reexplored in the setting of increasing concern over MRSA acquired in the community setting. Newer treatment options for MRSA include linezolid, quinupristin-dalfopristin, daptomycin, and tigecycline. With the exception of linezolid, these newer agents require intravenous administration. Combination therapy may be considered in select invasive diseases refractory to standard monotherapies. These diseases include infections such as endocarditis, meningitis, and prosthetic device infections. Additional alternatives to vancomycin are under clinical investigation. Those in later stages of development include oritavancin, dalbavancin, telavancin, and ceftobiprole.