Management of Community-Associated Methicillin-ResistantStaphylococcus aureusInfections in Children

Methicillin-resistant Staphylococcus aureus-associated empyema necessitans in a child: A case report and a literature review

Introduction

Empyema is a known complication of severe pleuropneumonia. In rare cases, if poorly treated, it could result in dissemination and fistulization and transformation into empyema necessitans. The manifestation may appear as a superficial abscess. However, as management highly differs, the recognition of potentially severe phenomenon is required.

Case Presentation

We describe a case of empyema necessitans on a 4-year-old girl secondary to methicillin-resistant Staphylococcus aureus. It represents the sixth pediatric case reported in the literature. It was managed by open drainage and prolonged antibiotherapy. The outcome was favorable as guidelines were extracted from similar reported cases.

Conclusion

Empyema necessitans remains a rare complication with significant morbidity. Prompt diagnosis and adapted management have relied on limited literature. As such, further reports are necessary to establish proper guidelines.

Methicillin-resistant Staphylococcus aureus-associated empyema necessitans in a child: A case report and a literature review

Introduction

Empyema is a known complication of severe pleuropneumonia. In rare cases, if poorly treated, it could result in dissemination and fistulization and transformation into empyema necessitans. The manifestation may appear as a superficial abscess. However, as management highly differs, the recognition of potentially severe phenomenon is required.

Case Presentation

We describe a case of empyema necessitans on a 4-year-old girl secondary to methicillin-resistant Staphylococcus aureus. It represents the sixth pediatric case reported in the literature. It was managed by open drainage and prolonged antibiotherapy. The outcome was favorable as guidelines were extracted from similar reported cases.

Conclusion

Empyema necessitans remains a rare complication with significant morbidity. Prompt diagnosis and adapted management have relied on limited literature. As such, further reports are necessary to establish proper guidelines.

Is community-associated methicillin-resistant Staphylococcus aureus (CA-MRSA) an emerging pathogen among children in Brazil?

Background

Community-associated methicillin-resistant Staphylococcus aureus (CA-MRSA) is spreading worldwide, but little is known about the epidemiology of this pathogen in Brazil.

Objective

To evaluate clinical and microbiological features of children with S. aureus infections admitted to a university hospital.

Methods

This was a cross-sectional study evaluating the potential risk factors for CA-MRSA, and a retrospective cohort evaluating in-hospital clinical outcomes. To include patients with both community and hospital-associated infections, we screened the results of the microbiological laboratory tests from January 1, 2012, to December 31, 2016. According to the phenotype, we classified the isolates in Methicillin-Susceptible S. aureus (MSSA), Hospital-Associated Methicillin-Resistant S. aureus (HA-MRSA), and CA-MRSA. Clinical data were collected from the patients’ medical records.

Results

We identified 279 cases of S. aureus infections (MSSA = 163, CA-MRSA = 69, HA-MRSA = 41). Overall, the incidence density of CA-MRSA and MSSA infections increased while the HA-MRSA incidence density decreased over the study period. CA-MRSA infected patients were more likely to present with skin and soft tissue infections (OR: 2.83, 95%CI: 1.54–5.33, p < 0.001) and osteomyelitis (OR: 4.76; 95%CI: 1.16–22.71, p = 0.014) when compared to MSSA and HA-MRSA infections. Unadjusted case fatality rates were similar between MSSA-infected patients (3.14%, 5/159) and CA-MRSA infected patients (3.80%, 3/79, p = 0.792), while HA-MRSA infected patients were more likely to die in the hospital (12.20%, 5/41, p = 0.013).

Conclusions

CA-MRSA is an emergent pediatric pathogen in Brazil. Our results highlight the relevance of choosing an appropriate initial antimicrobial drug for treating children with severe S. aureus infections.

Necrotizing pneumonia: an emerging problem in children?

BACKGROUND

In children, necrotizing pneumonia (NP) is an uncommon, severe complication of pneumonia. It is characterized by destruction of the underlying lung parenchyma resulting in multiple small, thin-walled cavities and is often accompanied by empyema and bronchopleural fistulae.

REVIEW

NP in children was first reported in children in 1994, and since then there has been a gradual increase in cases, which is partially explained by greater physician awareness and use of contrast computed tomography (CT) scans, and by temporal changes in circulating respiratory pathogens and antibiotic prescribing. The most common pathogens detected in children with NP are pneumococci and Staphylococcus aureus. The underlying disease mechanisms are poorly understood, but likely relate to multiple host susceptibility and bacterial virulence factors, with viral-bacterial interactions also possibly having a role. Most cases are in previously healthy young children who, despite adequate antibiotic therapy for bacterial pneumonia, remain febrile and unwell. Many also have evidence of pleural effusion, empyema, or pyopneumothorax, which has undergone drainage or surgical intervention without clinical improvement. The diagnosis is generally made by chest imaging, with CT scans being the most sensitive, showing loss of normal pulmonary architecture, decreased parenchymal enhancement and multiple thin-walled cavities. Blood culture and culture and molecular testing of pleural fluid provide a microbiologic diagnosis in as many as 50% of cases. Prolonged antibiotics, draining pleural fluid and gas that causes mass effects, and maintaining ventilation, circulation, nutrition, fluid, and electrolyte balance are critical components of therapy. Despite its serious nature, death is uncommon, with good clinical, radiographic and functional recovery achieved in the 5-6 months following diagnosis. Increased knowledge of NP's pathogenesis will assist more rapid diagnosis and improve treatment and, ultimately, prevention.

CONCLUSION

It is important to consider that our understanding of NP is limited to individual case reports or small case series, and treatment data from randomized-controlled trials are lacking. Furthermore, case series are retrospective and usually confined to single centers. Consequently, these studies may not be representative of patients in other locations, especially when allowing for temporal changes in pathogen behaviour and differences in immunization schedules and antibiotic prescribing practices.

Charged Nonclassical Antifolates with Activity Against Gram-Positive and Gram-Negative Pathogens

Although classical, negatively charged antifolates such as methotrexate possess high affinity for the dihydrofolate reductase (DHFR) enzyme, they are unable to penetrate the bacterial cell wall, rendering them poor antibacterial agents. Herein, we report a new class of charged propargyl-linked antifolates that capture some of the key contacts common to the classical antifolates while maintaining the ability to passively diffuse across the bacterial cell wall. Eight synthesized compounds exhibit extraordinary potency against Gram-positive S. aureus with limited toxicity against mammalian cells and good metabolic profile. High resolution crystal structures of two of the compounds reveal extensive interactions between the carboxylate and active site residues through a highly organized water network.

Linezolid is Associated with Improved Early Outcomes of Childhood Tuberculous Meningitis

BACKGROUND

Linezolid serves as an important component for the treatment of drug-resistant tuberculosis although there is little published data about linezolid use in children, especially in childhood tuberculous meningitis (TBM).

METHODS

In this study, we retrospectively reviewed records of childhood TBM patients who started treatment between January 2012 and August 2014. A total of 86 childhood TBM patients younger than 15 years old were enrolled. Out of 86 children, 36 (41.9%) received the regimen containing linezolid.

RESULTS

Thirty-two (88.9%) of 36 linezolid-treated cases had favorable outcomes, and 35 (70.0%) cases were successfully treated in the control group. The frequency of favorable outcome of linezolid group was significantly higher than that of control group (P = 0.037). In addition, compared with cases with fever clearance time of <1 week, the control group had more cases with fever clearance time of 1-4 weeks (P = 0.010) and >4 weeks (P = 0.000) than linezolid group. Furthermore, there was no significant difference in the frequency of adverse events between the two regimens (P = 0.896). In addition, the patients with adverse events were more likely to have treatment failure, the P value of which was 0.008.

CONCLUSIONS

Our data demonstrate that linezolid improves early outcome of childhood TBM. The low frequency of linezolid-associated adverse effects highlights the promising prospects of its use for treatment of childhood TBM.

Outpatient management of community-associated methicillin-resistant Staphylococcus aureus skin and soft tissue infection

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

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

The incidence of complicated pneumonias in children is increasing with a concurrent increase in the incidence of community-associated methicillin-resistant Staphylococcus aureus (CA-MRSA) infections. CA-MRSA is distinct from hospital associated MRSA [HA-MRSA] in regards to its genotype, epidemiology, and clinical course. Unlike HA-MRSA, CA-MRSA often strikes young, previously healthy children. Pneumonias caused by CA-MRSA have a rather distinct presentation. Because of its pore-forming toxins, namely Panton-Valentine leukocidin (PVL) and alpha-hemolysin, extensive necrotizing disease with corresponding hypoxaemia and hypercarbia is common. Other features include multilobar disease, leucopenia, haemoptysis, and high mortality rates. A previous influenza-like illness or skin and soft tissue infection [SSTI] often precede the development of pneumonia due to CA-MRSA. Vancomycin is recommended as first-line empiric therapy for suspected CA-MRSA infections. However, vancomycin is not an ideal agent for the treatment of pneumonia given its poor concentrating ability in alveolar fluid. Linezolid and clindamycin have also been used in the treatment of CA-MRSA pneumonia and ongoing research is looking for alternative antimicrobials. Recent studies have continued to report a lack of correlation between nasal colonization and active infections due to CA-MRSA. Given that the role of nasal colonization in CA-MRSA infection is not clear, the utility of decolonization treatment has been a point of debate. Finally, patients with cystic fibrosis are becoming increasingly colonized with MRSA as opposed to MSSA. There is some accumulating evidence that patients with MRSA show a more rapid deterioration in their degree of obstructive disease as measured by forced expiratory volume in one second (FEV(1)). However, it still is not clear whether MRSA is a marker for worsening disease or whether it actually is a cause of disease progression in cystic fibrosis. More longitudinal data is needed to understand how MRSA colonization impacts the course of disease in cystic fibrosis.

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.

High prevalence of ST121 in community-associated methicillin-susceptible Staphylococcus aureus lineages responsible for skin and soft tissue infections in Portuguese children

In order to evaluate the incidence of community-associated methicillin-resistant Staphylococcus aureus (CA-MRSA) in Portugal, we analyzed a collection of 38 S. aureus isolates recovered from 30 children attending the pediatric emergency department of a central hospital in Lisbon due to skin and soft tissue infections. Molecular characterization identified seven clonal lineages among the 35 methicillin-susceptible S. aureus (MSSA) isolates, of which the major lineage PFGE A/t159/ST121 included 63% of the isolates. The three MRSA isolates belonged to the Pediatric clone PFGE D/t535/ST5-IV (n = 2) and to the European CA-MRSA clone PFGE G/t044/ST80-IVc (n = 1). All isolates harbored several virulence factors, namely, leukocidins. Panton-Valentine leukocidin (PVL) was produced by isolates from five MSSA lineages and by the ST80 MRSA. Of interest, this is the first reported isolation of CA-MRSA ST80 in Portugal.

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.

Severe invasive community-associated methicillin-resistant Staphylococcus aureus infections in previously healthy children

OBJECTIVE

An increase in community-associated methicillin-resistant Staphylococcus aureus (CA-MRSA) infections has been reported in the literature. Most severe, life-threatening infections were previously thought to be associated with chronically ill or frail patients. Our pediatric intensive care unit (PICU) has seen a recent dramatic increase in primary, severe invasive CA-MRSA infections in healthy children.

DESIGN/SETTING

A retrospective chart review of all previously healthy patients admitted to our 19-bed combined medical-surgical PICU with a primary diagnosis of severe invasive, culture-proven CA-MRSA disease during the past 6 years.

RESULTS

Eleven previously healthy patients were admitted to our PICU with severe, primary, invasive CA-MRSA infections from March 2006 through September 2007, in contrast to no patients meeting these criteria in the preceding 5 years. The mortality rate was 27%, compared with an overall PICU mortality rate during the study period of <7%. The mean PICU length of stay of these patients was 14.9 days, compared with an average PICU length of stay of 2.4 days. Despite initiation of treatment with vancomycin at admission to the PICU in all but one case, patients took a mean of 5.7 days to convert to negative blood cultures. Eight patients had bacteremia longer than 4 days. Six of the patients developed bilateral necrotizing pneumonia requiring prolonged mechanical ventilation.

CONCLUSIONS

Severe CA-MRSA infections in healthy children are increasing at an alarming rate in our institution. This acute rise in incidence, coupled with an alarmingly high associated mortality rate, raises important questions about the initial empirical antibiotic therapy we use in caring for patients presenting with suspected life-threatening CA-MRSA disease. Vancomycin monotherapy may not be adequate treatment for severe CA-MRSA infections.

Inhibition of methionyl-tRNA synthetase by REP8839 and effects of resistance mutations on enzyme activity

REP8839 is a selective inhibitor of methionyl-tRNA synthetase (MetRS) with antibacterial activity against a variety of gram-positive organisms. We determined REP8839 potency against Staphylococcus aureus MetRS and assessed its selectivity for bacterial versus human orthologs of MetRS. The inhibition constant (K(i)) of REP8839 was 10 pM for Staphylococcus aureus MetRS. Inhibition of MetRS by REP8839 was competitive with methionine and uncompetitive with ATP. Thus, high physiological ATP levels would actually facilitate optimal binding of the inhibitor. While many gram-positive bacteria, such as Staphylococcus aureus, express exclusively the MetRS1 subtype, many gram-negative bacteria express an alternative homolog called MetRS2. Some gram-positive bacteria, such as Streptococcus pneumoniae and Bacillus anthracis, express both MetRS1 and MetRS2. MetRS2 orthologs were considerably less susceptible to REP8839 inhibition. REP8839 inhibition of human mitochondrial MetRS was 1,000-fold weaker than inhibition of Staphylococcus aureus MetRS; inhibition of human cytoplasmic MetRS was not detectable, corresponding to >1,000,000-fold selectivity for the bacterial target relative to its cytoplasmic counterpart. Mutations in MetRS that confer reduced susceptibility to REP8839 were examined. The mutant MetRS enzymes generally exhibited substantially impaired catalytic activity, particularly in aminoacylation turnover rates. REP8839 K(i) values ranged from 4- to 190,000-fold higher for the mutant enzymes than for wild-type MetRS. These observations provide a potential mechanistic explanation for the reduced growth fitness observed with MetRS mutant strains relative to that with wild-type Staphylococcus aureus.

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

PURPOSE

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

DATA

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

DATA SYNTHESIS

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

CONCLUSIONS

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

Retapamulin: a review of its use in the management of impetigo and other uncomplicated superficial skin infections

Topical retapamulin (Altabax, Altargo) is the first pleuromutilin antibacterial approved for the treatment of uncomplicated superficial skin infections caused by Staphylococcus aureus (excluding meticillin-resistant S. aureus [MRSA]) and Streptococcus pyogenes in patients aged > or = 9 months. In the EU, retapamulin is indicated for use in patients with impetigo or with infected small lacerations, abrasions or sutured wounds (without abscesses); in the US, it is indicated for use in patients with impetigo. Retapamulin has a novel site of action on bacterial ribosomes. In clinical trials in patients with impetigo, topical retapamulin 1% ointment twice daily for 5 days (the approved regimen) was superior to placebo; treatment with retapamulin was noninferior to that with topical fusidic acid. In patients with secondarily infected traumatic lesions, treatment with retapamulin was noninferior to that with oral cefalexin, although the efficacy of retapamulin was reduced in patients with MRSA infections or superficial abscesses. Retapamulin was well tolerated in both paediatric and adult patients, and the majority of adverse events were of mild to moderate severity. Thus, the introduction of topical retapamulin 1% ointment extends the treatment options available in the management of impetigo and uncomplicated secondarily infected traumatic lesions.

Epidemiology, clinical manifestations, and treatment options for skin and soft tissue infection caused by community-acquired methicillin-resistant Staphylococcus aureus

PURPOSE

This article reviews the evolving epidemiology of community-acquired methicillin-resistant Staphylococcus aureus (CA-MRSA) and the appropriate outpatient management of CA-MRSA skin and soft tissue infection. Further, the paper will provide the basis upon which an individualized patient educational plan may be developed.

DATA SOURCES

To complete this review, a search of English language publications was conducted through Medline and CINAHL databases (1966-2006).

CONCLUSIONS

The epidemiology of CA-MRSA is becoming increasingly complex. Research that addresses the impact of this organism in high-risk populations and within families is urgently needed.

IMPLICATIONS FOR PRACTICE

Nurse practitioners must remain informed of the epidemiology of common and emerging drug-resistant organisms in their patient populations.

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

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