Infective Pyomyositis and Myositis in Children in the Era of Community‐Acquired, Methicillin‐ResistantStaphylococcus aureusInfection

Tropical pyomyositis

Tropical pyomyositis is a serious infectious disease characterised by the formation of abscesses in the skeletal muscles and is primarily caused by Staphylococcus aureus, with an increasing incidence in non-tropical regions. The disease primarily affects men and young adults, often following minor trauma, with an increasing incidence in immunocompromised individuals. Immunocompromised hosts are more likely to be affected by Gram-negative organisms, Mycobacterium tuberculosis, opportunistic infections such as fungal pathogens, non-tuberculous mycobacteria, and Nocardia species. Diagnosis is complicated by non-specific symptoms and the low yield of blood cultures, so imaging studies such as Magnetic Resonance Imaging (MRI) are required for accurate identification. Treatment focuses on controlling the source through drainage, tailored antibiotic therapy, and supportive care, especially in patients with complications such as multi-organ dysfunction. Given the complex clinical manifestations, heightened awareness and a collaborative approach to education and resource provision are critical to improving outcomes in patients with tropical pyomyositis.

Molecular Epidemiology Clinical Manifestations, Decolonization Strategies, and Treatment Options of Methicillin-Resistant Staphylococcus aureus Infection in Neonates

Preterm and low-birth-weight neonates are particularly susceptible to methicillin-resistant Staphylococcus aureus (MRSA) colonization, whereas MRSA infection is associated with significant neonatal morbidity and mortality globally. The objective of our study was to examine the current body of knowledge about molecular traits, epidemiology, risk factors, clinical presentation, decolonization techniques, and available treatments for MRSA infection in neonates. MRSA strains that predominate in neonatal units, namely healthcare-associated (HA)-MRSA, differ from community-acquired (CA)-MRSA strains in molecular characteristics, toxin synthesis, including Panton-Valentine leukocidin, and resistance to antibiotics. Colonization with MRSA predisposes neonates to infection. The clinical impact of MRSA infection includes bacteremia, sepsis, pneumonia, endocarditis, osteomyelitis, septic arthritis, skin and soft tissue infections, and toxic shock syndrome. To reduce MRSA transmission, colonization, and infection, customized approaches are required, including continuous surveillance of MRSA epidemiology, new techniques for detecting MRSA resistance, and the application of basic preventive measures. Antimicrobial susceptibility monitoring is essential to identify the best empirical antimicrobial treatments. The growing antibiotic resistance of MRSA remains challenging, and vancomycin is still the best option. Further extensive research and surveillance are warranted to explore the genetic diversity and prevalence of MRSA.

Radiological Identification and Review of Lumbosacral Paraspinal Muscle Pyomyositis and Abscesses in a Young Male With Streptococcus Bacteremia: A Case Report

We present a case report of a 21-year-old male patient with lumbosacral pyomyositis and abscesses secondary to Streptococcus parasanguinis, along with a review of the literature. The patient was admitted with acute metabolic encephalopathy, rhabdomyolysis secondary to cannabinoid use, acute kidney injury, and right lower extremity weakness. T2-weighted magnetic resonance imaging (MRI) of the lumbar region demonstrated multiple ring-enhancing nodular lesions within the left multifidus muscles, left erector spinae muscle, and left quadratus lumborum muscle. He was successfully treated with ceftriaxone and discharged on cefadroxil with improved right lower extremity strength. This case highlights MRI as an integral modality for the detection and treatment guidance of pyomyositis, providing a relevant microbiological-radiological association for rare causes of pyomyositis, such as Streptococcus parasanguinis.

Dysphagia and Trismus After Tooth Extraction : Clinical Conondrum

Clinicians should consider disorders of masticatory muscle including lateral pterygoid muscle as a differential diagnosis in patients presenting with dysphagia and trismus after tooth extraction.

Clinical Characteristics and Management of Children and Adolescents Hospitalized With Pyomyositis

BACKGROUND

Pyomyositis, a bacterial muscle infection, is an important differential diagnosis in children and adolescents with musculoskeletal pain. In contrast to tropical regions, it is rarely recognized in temperate countries, but incidence is increasing and major studies are missing.

METHODS

This retrospective multicenter study included patients <18 years of age hospitalized with pyomyositis in 11 Swiss children's hospitals between January 2010 and December 2022. Cases were identified by ICD-10 code (Myositis; M60-M60.9), and data was extracted from electronic hospital records.

RESULTS

Of 331 patients identified, 102 fulfilled the case definition. Patient age at presentation ranged from 2 weeks to 17 years (median 8 years). The majority had no underlying illness and all presented with fever and localized pain. At the respective site of pyomyositis, 100 (98%) had impaired movement and 39 (38%) presented with local swelling. Pelvic (57%) and leg (28%) muscles were mostly affected. Blood or tissue cultures were obtained in 94 (92%) and 59 (57%) patients, respectively. Of those, 55 (58%) blood and 52 (88%) tissue cultures were positive, mainly for Staphylococcus aureus (35 and 19, respectively) and Streptococcus pyogene s (12 and 15, respectively). All patients received antibiotic treatment during hospitalization for a median of 10 days (interquartile range: 7-17), followed by outpatient treatment for a further median of 16 days (interquartile range: 11-22) in 95 (93%) patients. Fifty-nine (57%) patients required surgery.

CONCLUSIONS

Pyomyositis is a challenging diagnosis that requires a high level of awareness. Blood and/or tissue cultures revealed S. aureus and S. pyogenes as the predominant causative agents.

Arthritis or an Adjacent Fascial Response? A Case Report of Combined Pyomyositis and Aseptic Arthritis

Pyomyositis, accompanied by aseptic arthritis, has been previously documented in several publications. However, none of the authors in the mentioned case reports offered a pathophysiological explanation for this unusual phenomenon or proposed a treatment protocol. We present a case of a healthy, 70-year-old male who was presented to the emergency department 4 days after tripping over a pile of wooden planks and getting stabbed by a nail to his thigh. The right thigh was swollen. Unproportional pain was produced by a light touch to the thigh. A laboratory test and a CT scan were obtained. The working diagnosis was pyomyositis of the thigh and septic arthritis of the ipsilateral knee. The patient underwent urgent debridement and irrigation of his right thigh. An arthroscopic knee lavage was performed as well. Intraoperative cultures from the thigh revealed the growth of Streptococcus pyogenes and Staphylococcus aureus. Cultures from synovial fluid were sterile; thus, septic arthritis was very unlikely. The source of the knee effusion might have been an aseptic inflammatory response due to the proximity of the thigh infection. Anatomically, the quadriceps muscle inserts on the patella, and its tendon fuses with the knee capsule, creating a direct fascial track from the thigh to the knee. The inflammatory response surrounding the infection may have followed this track, creating a domino effect, affecting adjacent capillaries within the joint capsule, and causing plasma leakage into the synovial space, leading to joint effusion. Our suggested treatment is addressing the primary infection with antibiotics and considering adding anti-inflammatory therapy, given our suspicion that this process has an inflammatory component.

Infectious factors in myocarditis: a comprehensive review of common and rare pathogens

BACKGROUND

Myocarditis is a significant health threat today, with infectious agents being the most common cause. Accurate diagnosis of the etiology of infectious myocarditis is crucial for effective treatment.

MAIN BODY

Infectious myocarditis can be caused by viruses, prokaryotes, parasites, and fungi. Viral infections are typically the primary cause. However, some rare opportunistic pathogens can also damage heart muscle cells in patients with immunodeficiencies, neoplasms and those who have undergone heart surgery.

CONCLUSIONS

This article reviews research on common and rare pathogens of infectious myocarditis, emphasizing the complexity of its etiology, with the aim of helping clinicians make an accurate diagnosis of infectious myocarditis.

Changing spectrum of primary pyomyositis in North India

Recent data have demonstrated the changing epidemiology of primary pyomyositis worldwide. Our hospital-based retrospective study investigated the clinical and microbiological spectrum of primary pyomyositis between 2013 and 2021 in PGIMER (Chandigarh), India. Over a quarter had predisposing conditions, mainly diabetes mellitus and immunosuppressive therapy. Fever, muscle pain, local swelling and breathlessness were the usual presentations, with quadriceps, iliopsoas and gluteal muscles commonly affected. Staphylococcus aureus was the predominant cause, with c.50% methicillin-resistant strains. Almost two-thirds presented with metastatic infection (stage 3 pyomyositis), frequently with septic lung emboli. Patients with methicillin-sensitive and resistant Staphylococcus aureus had a similar incidence of metastatic infection. In-hospital mortality was c.10% and was strongly associated with a high international normalised ratio. Primary pyomyositis remains a significant problem, with a dramatic increase in community-associated methicillin-resistant Staphylococcus aureus.

Pediatric musculoskeletal infections

PURPOSE OF REVIEW

The aim of this article is to review the recent guidelines and literature regarding the diagnosis and the treatment of common pediatric musculoskeletal infections: septic arthritis, osteomyelitis, pyomyositis, and Lyme disease.

RECENT FINDINGS

In the last decade, a better understanding of the causative organisms of common bacterial infections, including Kingella , leads to prompt targeted antimicrobial coverage in all musculoskeletal infections. Prompt diagnosis and treatment continues to be the mainstay in the treatment of children with osteoarticular infections. Efforts to improve early detection have lead to improving rapid lab diagnostic testing; however, more advanced diagnostics such as arthrocentesis for septic arthritis and MRI for osteomyelitis and pyomyositis, remain the gold standard. Shorter and narrowed antibiotic courses, with appropriate transition to outpatient oral treatment provide effective infection clearance and reduction in complications of disease.

SUMMARY

Advances in diagnostics, including pathogen identification as well as imaging continues to improve our ability to diagnose and treat these infections, although still lack ability to provide definitive diagnosis without more invasive nor advanced techniques.

Primary MRSA Myositis Mimicking Septic Arthritis

As the incidence of bacterial myositis and pyomyositis in the United States is rising, we aim to highlight the presentation of bacterial myositis which is known as a great imitator in tropical regions. This is a case report of a 61-year-old female patient with poorly controlled diabetes who presented initially with lateral hip pain and tenderness. This was initially believed to be septic arthritis and warranted arthrocentesis. What makes this case interesting is that what was believed to be a primary community-acquired MRSA myositis, which progressed to a life-threatening septic shock, happened in a nontropical area (Northeastern USA) and in a patient with no underlying recent muscle injury. This case serves to remind clinicians that infectious myositis is gaining more incidence in nontropical regions and can masquerade as septic arthritis, requiring a high index of suspicion. Normal muscle enzymes like CK and aldolase do not rule out myositis.

Pelvic Pyomyositis in Childhood: Clinical and Radiological Findings in a Tertiary Pediatric Center

Pyomyositis (PM) is an infrequent but increasing bacterial infection of the skeletal muscle, with muscles of the pelvis and thigh frequently involved. The diagnosis is often challenging, especially when a deep muscle is affected. We present a single-center pediatric cohort affected by pelvic PM. A retrospective analysis was performed, including children admitted to Meyer Children’s Hospital between 2010 and 2020. Demographic, anamnestic, clinical, laboratory, radiological and management data were collected. Forty-seven patients (range 8 days–16.5 years, 66% males) were selected. Pain (64%), functional limitations (40%) and fever (38%) were the most common presenting symptoms; 11% developed sepsis. The median time to reach the diagnosis was 5 days (IQR 3–9). Staphylococcus aureus was the most common organism (30%), Methicillin-Resistant S aureus (MRSA) in 14%. PM was associated with osteomyelitis (17%), arthritis (19%) or both (45%). The infection was multifocal in 87% of children and determined abscesses in 44% (40% multiple). Pelvic MRI scan, including diffusion-weighted imaging (DWI), always showed abnormalities when performed. Clinical and laboratory findings in pelvic PM are unspecific, especially in infancy. Nevertheless, the infection may be severe, and the suspicion should be higher. MRI is the most useful radiological technique, and DWI sequence could reveal insidious infections.

Whole genome sequencing and molecular epidemiology of pediatric Staphylococcus aureus bacteremia

BACKGROUND

The role Staphylococcus aureus antimicrobial resistance genes and toxins play in disease severity, management and outcome in childhood is an emerging field requiring further exploration.

METHODS

A prospective multi-site study of Australian and New Zealand children hospitalized with S. aureus bacteremia (SAB), occurred over 24-months (2017-2018). Whole genome sequencing (WGS) data was paired with clinical information from the ISAIAH cohort.

RESULTS

353 SAB isolates were sequenced; 85% methicillin-susceptible S. aureus ([MSSA], 301/353); 15% methicillin-resistant S. aureus ([MRSA], 52/353). There were 92 sequence types (STs), most commonly; ST5 (18%) and ST30 (8%), grouped into 23 clonal complexes (CCs), most frequently CC5 (21%) and CC30 (12%). MSSA comprised the majority of healthcare-associated SAB (87%, 109/125), with principal clones CC15 (48%, 11/21) and CC8 (33%, 7/21). Panton Valentine Leukocidin (PVL)-positive SAB occurred in 22% (76/353); predominantly MSSA (59%, 45/76), community-onset (92%, 70/76) infections. For community-onset SAB, the only microbiological independent predictor of poor outcomes was PVL-positivity (aOR 2.6 [CI 1.0-6.2]).

CONCLUSION

From this WGS pediatric SAB data, we demonstrate the previously under-recognized role MSSA has in harboring genetic virulence and causing healthcare-associated infections. PVL-positivity was the only molecular independent predictor of poor outcomes in children. These findings underscore the need for further research to define the potential implications PVL-producing strains may have on approaches to S. aureus clinical management.

Evolutionary Divergence of the Novel Staphylococcal Species Staphylococcus argenteus

Currently, invasive infections caused by Staphylococcus argenteus, which is a recently named staphylococcal species, are increasingly reported worldwide. However, only a few genomic studies of S. argenteus have offered comprehensive information regarding its genetic diversity, epidemiological characteristics, antimicrobial resistance genes (ARGs), virulence genes and other profiles. Here, we describe a comparative genomic analysis by population structure, pangenome, panmobilome, region-specific accessory genes confer an adaptive advantage in 153 S. argenteus strains which comprised 24 strains sequenced in this study and 129 strains whose genome sequences were available from GenBank. As a result, the population of S. argenteus comprised seven genetically distinct clades, including two major clades (C1 and C2), with distinct isolation source patterns. Pangenome analysis revealed that S. argenteus has an open pangenome composed of 7,319 genes and a core genome composed of 1,508 genes. We further determined the distributions of 75 virulence factors (VFs) and 30 known ARGs and identified at least four types of plasmids and 93 complete or partial putative prophages. It indicate that S. argenteus may show a similar level of pathogenicity to that of S. aureus. This study also provides insights into the evolutionary divergence of this pathogen, indicating that the geographical distribution was a potential driving force behind the evolutionary divergence of S. argenteus. The preferential horizontal acquisition of particular elements, such as staphylococcal cassette chromosome mec elements and plasmids, was observed in specific regions, revealing potential gene exchange between S. argenteus strains and local S. aureus strains. Moreover, multiple specific genes related to environmental adaptation were identified in strains isolated from East Asia. However, these findings may help promote our understanding of the evolutionary divergence of this bacterium at a high genetic resolution by providing insights into the epidemiology of S. argenteus and may help combat its spread.

Primary pyomyositis in an infant following one-day afebrile upper limb monoplegia

Background : Pyomyositis is a subacute bacterial infection of the skeletal muscles. Its most common features are fever, muscle swelling, and focal pain. There have been insufficient data regarding pyomyositis in healthy infants. Case report : A one-month-old boy presented with an impairment of his left arm movement. He was well-nourished and not under any apparent distress. His vital signs were within the normal limits but neurological examination revealed left forearm paralysis. Physical examination showed no abnormal findings in the region from the left shoulder joint to the fingertips. Considering these factors, an intracranial pathology was initially suspected. However, he developed a fever, regular tachycardia, and swelling in the left forearm. Magnetic resonance imaging revealed inflammation in the left forearm muscles. He was diagnosed with bacterial myositis and started on intravenous antibiotics. On the 17th day, he was discharged with oral antibiotic treatment, which was completed over 25 days without any sequelae nor relapse. Conclusion : Here we report the case of Japanese primary pyomyositis following one-day afebrile upper limb monoplegia in an infant. Even when infants exhibit afebrile symptoms, a bacterial infection should be suspected. J. Med. Invest. 68 : 372-375, August, 2021.

An Unusual Presentation of Community-Acquired Methicillin-Resistant Staphylococcus aureus Infection in a Child Treated With Linezolid

Methicillin-resistant Staphylococcus aureus (MRSA) infection is a major public health concern. MRSA isolates are classified into community-acquired MRSA (CA-MRSA) and healthcare-associated MRSA based on their epidemiology, antibiotic susceptibility patterns, and molecular characteristics. CA-MRSA typically causes skin and soft tissue infections. However, the incidence of invasive infections has increased in recent years. This paper describes the case of a 12-year-old girl with an unusual presentation of CA-MRSA. The patient presented with right thigh pyomyositis complicated by deep vein thrombosis, septic pulmonary embolism, and necrotizing pneumonia. The MRSA isolate was susceptible to vancomycin but resistant to the other anti-MRSA antibiotics. The patient was successfully treated with linezolid after clinical deterioration with vancomycin. A literature review comparing vancomycin and linezolid in invasive MRSA infections among children indicated that linezolid has better lung and tissue penetration than vancomycin, and an early switch is warranted in the case of deterioration after vancomycin administration and the lack of other alternatives.

Primary Bacterial Pyomyositis in Children: A Systematic Review

BACKGROUND

Tropical pyomyositis has had a recent increase in the United States, Europe, and other nontropical areas. The purpose of this study was to provide an accurate description of the demographics, presenting features, sites of involvement, microbiology, imaging modalities, medical and surgical management, complications, and predictors of clinical course.

METHODS

We searched PubMed, Cochrane, Web of Science Collection, Scopus, and Embase databases yielding 156 studies. Of these, 23 articles were selected for statistical analysis.

RESULTS

The average age at presentation was 8.4±1.9 years with males more commonly affected. Fever, painful limp, and localized pain were the most common presenting symptoms. Pelvis, lower extremity, trunk and spine, in descending order, were the most commonly affected locations. Iliopsoas, obturator musculature, and gluteus musculature were the most commonly affected muscle groups. The mean time to diagnosis was 6.6±3.05 days. Staphylococcus aureus was the most common offending organism. The mean length of hospital stay was 12.0±4.6 days. Medical management alone was successful in 40% of cases (143/361) with an average duration of 9.5±4.0 and 22.7±7.2 days of intravenous and oral antibiotics, respectively. Surgical management consisted of open drainage in 91.3% (199/218) or percutaneous drainage in 8.7% (19/218) of cases. Painful limp, fever, and larger values of white cell count and erythrocyte sedimentation rate were associated with an increased need for surgery. Obturator and calf muscle involvement were strongly associated with multifocal involvement. There were 42 complications in 41 patients (11.3%). Methicillin-resistant S. aureus was associated with an increased risk of complications. The most common complications were osteomyelitis, septicemia, and septic arthritis.

CONCLUSIONS

Primary pyomyositis should be considered in cases suggesting pediatric infection. Magnetic resonance imaging is the most commonly used imaging modality; however, ultrasound is useful given its accessibility and low cost. Medical management alone can be successful, but surgical treatment is often needed. The prognosis is favorable. Early diagnosis, appropriate medical management, and potential surgical drainage are required for effective treatment.

LEVEL OF EVIDENCE

Level IV-systematic review.

Genome Sequences of Community Carriage Strains of Staphylococcus aureus from Yuma, Arizona

Staphylococcus aureus exists as a pathogen and commensal. Individuals with asymptomatic carriage serve as a reservoir for transmission and are at increased risk of infecting themselves. In order to characterize the genomic diversity of S. aureus circulating in the community, we sequenced 166 genomes collected from individuals in Yuma, AZ.

Intraperitoneal vancomycin treatment of multifocal methicillin-resistant Staphylococcus aureus osteomyelitis in a patient on peritoneal dialysis

PURPOSE

We report the case of a 2-year-old girl with end-stage renal disease managed by peritoneal dialysis (PD) who developed methicillin-resistant staphylococcal osteomyelitis of the left shoulder and was successfully treated with intraperitoneal (IP) administration of vancomycin for 2 weeks followed by oral clindamycin therapy.

SUMMARY

The patient was hospitalized with tactile fever and a 3-day history of worsening fussiness. Radiography of the left shoulder showed findings indicative of osteomyelitis. Vancomycin was administered via central venous line for 3 days, during which time the patient underwent PD 24 hours a day. After magnetic resonance imaging revealed proximal humeral osteomyelitis, septic arthritis of the shoulder joint, and osteomyelitis of the scapula, the patient underwent incision and drainage of the left shoulder joint. Both blood and joint drainage cultures grew methicillin-resistant Staphylococcus aureus that was sensitive to vancomycin. The patient's central venous catheter was removed on hospital day 4; due to difficulties with peripheral i.v. access and a desire to avoid placing a peripherally inserted central venous catheter, vancomycin administration was changed to the IP route, with vancomycin added to the PD fluid. During IP treatment, serum vancomycin levels were maintained at 13.5 to 18.5 mg/L, and the calculated ratio of vancomycin area under the curve to minimum inhibitory concentration was maintained above 400. After completing a 14-day course of IP vancomycin therapy, the patient was switched to oral clindamycin, with subsequent complete resolution of osteomyelitis.

CONCLUSION

IP vancomycin was effective for treatment of invasive S. aureus infection in this case. This approach should be considered in patients undergoing PD for whom peripheral i.v. access options are limited and/or not preferred.

Factors associated with pyomyositis: A systematic review and meta-analysis

OBJECTIVES

Pyomyositis, an acute bacterial infection of skeletal muscle usually resulting in abscess formation, is well recognised in tropical regions where it can account for up to 4% of adult surgical admissions. It is increasingly being reported from high-income temperate countries. Pyomyositis occurs across all ages and in both sexes. Mortality ranges from 1% to 23%. Many risk factors have been suggested. We aimed to identify factors associated with pyomyositis.

METHODS

We undertook a systematic review and meta-analysis, using PubMed, EMBASE, Scopus and the Cochran Library and hand-searching published papers. The random-effects model meta-analysis was used to calculate pooled estimated odd ratios with the corresponding 95% confidence interval.

RESULTS

All studies in the systematic review (n = 25) and the meta-analysis (n = 12) were hospital-based. Seven only included children. Relatively few studies have been published in the last decade, the majority of which are from high-income temperate settings. Staphylococcus aureus was the main organism isolated. Males under the age of 20 predominated, and mortality of up to 20% was reported. Factors associated with pyomyositis were HIV infection (OR = 4.82; 95% CI: 1.67-13.92) and fulfilling an AIDS surveillance definition (OR = 6.08; 95% CI: 2.79-13.23).

CONCLUSIONS

Our meta-analysis indicated significant associations between pyomyositis infection and HIV/AIDS. Major gaps in our understanding of the epidemiology, pathogenesis, clinical presentation, and outcome remain, highlighting the need for further research and more systematic studies. Pyomyositis merits consideration as a neglected tropical disease.

Infective myositis

Myositis is inflammation especially of the voluntary muscles, characterized by localized or diffuse pain, tenderness on movement or palpation, swelling, and/or weakness. The two main categories of myositis include non-infectious and infectious. Infective myositis may be due to a wide variety of pathogens, including bacteria, fungi, viruses, and parasites. A brief account of the various pathogens causing infective myositis is discussed.

Methicillin Resistant Staphylococcus Aureus Shoulder Pyomyositis with Multifocal Lung Infiltrations

Pyomyositis is a rare condition in temperate climates. We present a case of Methicillin Resistant Staphylococcus aureus pyomyositis of the shoulder complicated by multifocal lung infiltrations, treated successfully with antibiotic therapy. After excluding shoulder septic arthritis, a low threshold of suspicion for the diagnosis of shoulder pyomyositis should be applied to patients with persistent fever, pain, and decreased range of shoulder motion. A prompt diagnosis and a rapid rise in antibiotic therapy are important to avoid local and systemic complications.

Development of a vaccine against Staphylococcus aureus invasive infections: Evidence based on human immunity, genetics and bacterial evasion mechanisms

Invasive Staphylococcus aureus infections are a leading cause of morbidity and mortality in both hospital and community settings, especially with the widespread emergence of virulent and multi-drug resistant methicillin-resistant S. aureus strains. There is an urgent and unmet clinical need for non-antibiotic immune-based approaches to treat these infections as the increasing antibiotic resistance is creating a serious threat to public health. However, all vaccination attempts aimed at preventing S. aureus invasive infections have failed in human trials, especially all vaccines aimed at generating high titers of opsonic antibodies against S. aureus surface antigens to facilitate antibody-mediated bacterial clearance. In this review, we summarize the data from humans regarding the immune responses that protect against invasive S. aureus infections as well as host genetic factors and bacterial evasion mechanisms, which are important to consider for the future development of effective and successful vaccines and immunotherapies against invasive S. aureus infections in humans. The evidence presented form the basis for a hypothesis that staphylococcal toxins (including superantigens and pore-forming toxins) are important virulence factors, and targeting the neutralization of these toxins are more likely to provide a therapeutic benefit in contrast to prior vaccine attempts to generate antibodies to facilitate opsonophagocytosis.

Update on Acute Bone and Joint Infections in Paediatrics: A Narrative Review on the Most Recent Evidence-Based Recommendations and Appropriate Antinfective Therapy

Acute bone and joint infections (BJIs) in children may clinically occur as osteomyelitis (OM) or septic arthritis (SA). In clinical practice, one-third of cases present a combination of both conditions. BJIs are usually caused by the haematogenous dissemination of septic emboli carried to the terminal blood vessels of bone and joints from distant infectious processes during transient bacteraemia. Early diagnosis is the cornerstone for the successful management of BJI, but it is still a challenge for paediatricians, particularly due to its nonspecific clinical presentation and to the poor specificity of the laboratory and imaging first-line tests that are available in emergency departments. Moreover, microbiological diagnosis is often difficult to achieve with common blood cultures, and further investigations require invasive procedures. The aim of this narrative review is to provide the most recent evidence-based recommendations on appropriate antinfective therapy in BJI in children. We conducted a review of recent literature by examining the MEDLINE (Medical Literature Analysis and Retrieval System Online) database using the search engines PubMed and Google Scholar. The keywords used were “osteomyelitis”, OR “bone infection”, OR “septic arthritis”, AND “p(a)ediatric” OR “children”. When BJI diagnosis is clinically suspected or radiologically confirmed, empiric antibiotic therapy should be started as soon as possible. The choice of empiric antimicrobial therapy is based on the most likely causative pathogens according to patient age, immunisation status, underlying disease, and other clinical and epidemiological considerations, including the local prevalence of virulent pathogens, antibiotic bioavailability and bone penetration. Empiric antibiotic treatment consists of a short intravenous cycle based on anti-staphylococcal penicillin or a cephalosporin in children aged over 3 months with the addition of gentamicin in infants aged under 3 months. An oral regimen may be an option depending on the bioavailability of antibiotic chosen and clinical and laboratory data. Strict clinical and laboratory follow-up should be scheduled for the following 3–5 weeks. Further studies on the optimal therapeutic approach are needed in order to understand the best first-line regimen, the utility of biomarkers for the definition of therapy duration and treatment of complications.

Prevalence, clinical expression, invasiveness and outcome of Staphylococcus aureus containing Panton-Valentine leukocidin in children treated in a university hospital of Lithuania

Background: There is a high prevalence of Staphylococcus aureus virulence factor Panton-Valentine leukocidin (PVL) in North-East parts of Europe. The aim was to evaluate data regarding the PVL occurrences in Lithuania, determine the relationship with Methicillin resistant Staphylococcus aureus (MRSA), association with demographic and clinical conditions, invasiveness and severity of the disease in children treated in hospital Kauno klinikos (KK).Methods: We performed a prospective case-cohort single-center study on paediatric patients hospitalized from 2012 to 2015 to KK. We compared characteristics in PVL positive [SA-PVL(+)] and PVL negative [SA-PVL(-)] groups among non-invasive and invasive infections. Logistic regression was performed to detect PVL predicting factors and Cox regression was presented to define factors associated with admission to intensive care unit (ICU).Results: PVL was detected in 51.5%, MRSA in 7.0% and MRSA-PVL(+) in 4.8% of cases. In general, PVL was associated with older age comparing with SA-PVL(-) (median 8.5 vs. 4.0 years, p < .001). Skin and soft tissue infections were presented in 87.9% of all SA-PVL(+) cases. Invasive infections (44.7% vs. 12.1%, p < .001) and co-morbidities (20.5% vs. 2.9%, p < .001) were associated with SA-PVL(-) infections compared to SA-PVL(+), but ICU admission number was higher in invasive SA-PVL(+) cases comparing to invasive SA-PVL(-) cases (41.2% vs. 10.2%, p = .007).Conclusions: There was a high prevalence of pvl gene in patients treated in KK. SA-PVL(+) infections were associated with SSTI and were not common in invasive infections, but the invasive infections caused by SA-PVL(+) were related to severe disease progression and admission to ICU.

Pyomyositis in the United States 2002-2014

OBJECTIVES

Primary pyomyositis is a bacterial infection of skeletal muscle first recognized in tropical regions of the world but needing characterization in temperate climates.

METHODS

This population-based study used the Healthcare Utilization Project/Nationwide Inpatient Sample database to characterize the trends of pyomyositis admissions in the United States from 2002-2014 using ICD-9 diagnostic codes.

RESULTS

We found a concerning more than three-fold increase in the incident pyomyositis admissions over our study period. The median length of stay was over twice as long compared to other hospitalized patients. Patients with pyomyositis were younger and more likely to be male and Black. There were more cases in the West and South compared to Midwest and Northeast. Age-adjusted odds ratios revealed significant association of pyomyositis with HIV, types 1 and 2 diabetes mellitus, hematologic malignancy, organ transplant, malnutrition, chronic kidney disease, obesity, and rheumatoid arthritis. The most commonly identified bacterial diagnosis was Staphylococcus aureus. Pseudomonas species were the most commonly identified gram-negative bacteria.

CONCLUSION

This nationwide review of pyomyositis in the United States suggests a concerning increase in incidence and provides information on the trends, demographics, risk factors, and causative organisms for pyomyositis in the United States.

Antimicrobial hydrogels based on PVA and diphlorethohydroxycarmalol (DPHC) derived from brown alga Ishige okamurae: An in vitro and in vivo study for wound dressing application

In this study, we fabricated polyvinyl alcohol hydrogels containing diphlorethohydroxycarmalol (DPHC) from Ishige okamurae for its anti-bacterial effect in wound-dressing applications. First, the minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) of DPHC against Staphylococcus aureus and Pseudomonas aeruginosa were investigated, and these were found to be about 128 μg/mL and 512 μg/mL, respectively. Polyvinyl alcohol hydrogels loaded with different concentrations of DPHC were then produced for the dressing of wounds to assist in the healing process and to provide an antibacterial effect. To investigate the characteristics of the proposed PVA/DPHC hydrogels, we conducted SEM analysis, rheological analysis, thermogravimetric analysis, water swelling analysis, drug release testing, and gel fraction assessment. The antibacterial activity of the PVA/DPHC hydrogels was also tested against the gram-positive bacterium S. aureus and the gram-negative bacterium P. aeruginosa using ASTM E2149 tests. The biocompatibility of the PVA/DPHC hydrogels was assessed using in vitro indirect and direct contact tests and in vivo tests on ICR mice. The PVA/DPHC hydrogels exhibited the ability to reduce the viability of S. aureus and P. aeruginosa by about 99% in ASTM E2149 testing, while not producing any toxic effect on NHDF-Neo or HaCaT cells as shown in MTT assays and in vitro FDA fluorescence analysis. In addition, the PVA/DPHC hydrogels had a strong wound healing effect when compared to non-treated groups of ICR mice in vivo. Based on the characterization of the PVA/DPHC hydrogels in vitro and in vivo, this study suggests that the proposed hydrogel has significant potential for use in wound dressing.

Experience With a Care Process Model in the Evaluation of Pediatric Musculoskeletal Infections in a Pediatric Emergency Department

OBJECTIVES

Care process models (CPMs) for certain conditions have improved clinical outcomes in children. This study describes the implementation and impact of a CPM for the evaluation of musculoskeletal infections in a pediatric emergency department (ED).

METHODS

A retrospective pre-post intervention study was performed to analyze the impact of a musculoskeletal infection CPM. Patients were identified retrospectively through electronic order history for imaging of an extremity or joint and recommended laboratory tests. Clinical outcomes evaluated included hospital length of stay (LOS), time to magnetic resonance imaging (MRI), time to administration of antibiotics, hospital admission rate, and 30-day readmission rate.

RESULTS

Musculoskeletal infection evaluations completed in the ED were reviewed from 1 year before implementation (n = 383) and 2 years after implementation (n = 1219) of the CPM. A significant improvement in the time to antibiotic administration for all patients (4.3 vs 3.7 hours, P < 0.05) and for patients with confirmed musculoskeletal infections (9.5 vs 4.9 hours, P < 0.05) was observed after the implementation of the CPM. The overall time to MRI (13.2 vs 10.3 hours, P = 0.29) and hospital LOS (4.7 vs 3.7 days, P = 0.11) were improved for all patients but were not statistically significant. The admission rate and 30-day readmission were similar before and after the implementation of the CPM.

CONCLUSIONS

The implementation of a musculoskeletal infection CPM has standardized the approach to the evaluation and diagnosis of musculoskeletal infections resulting in a significant decrease in the time to administer antibiotics and a downward trend in time to MRI and hospital LOS.

Psoitis and multiple venous thromboses caused by Panton Valentine Leukocidin-positive methicillin-sensitive Staphylococcus aureus in a 12-year-old girl: A case report

Panton Valentine Leukocidin (PVL) is one of the many toxins produced by Staphylococcus aureus. In Japan, PVL-positive S. aureus strains are mainly methicillin-resistant S. aureus (MRSA). Data regarding PVL-positive methicillin-sensitive S. aureus (MSSA) are scarce. In this report, we describe a case of severe infection by PVL-positive MSSA. A 12-year-old healthy girl was admitted with high fever and pain in the lower back. Computed tomography revealed a diagnosis of psoitis and multiple venous thromboses. Blood cultures obtained after admission revealed infection with MSSA. Her fever continued despite adequate antibiotic therapy. On the fifth hospitalization day, she developed bladder dysfunction, and an abscess was noted near the third lumbar vertebra. She underwent an emergency operation and recovered. Bacterial analyses revealed that the causative MSSA was a PVL-producing single variant of ST8 (related to USA300clone), of sequence type 2149. PVL is known to cause platelet activation. This case demonstrates the need for detailed analyses of the causative strain of bacteria in cases of S. aureus infection with deep vein thrombosis, even in cases of known MSSA infection.

Panton-Valentine leucocidin is the key determinant of Staphylococcus aureus pyomyositis in a bacterial GWAS

Pyomyositis is a severe bacterial infection of skeletal muscle, commonly affecting children in tropical regions, predominantly caused by Staphylococcus aureus. To understand the contribution of bacterial genomic factors to pyomyositis, we conducted a genome-wide association study of S. aureus cultured from 101 children with pyomyositis and 417 children with asymptomatic nasal carriage attending the Angkor Hospital for Children, Cambodia. We found a strong relationship between bacterial genetic variation and pyomyositis, with estimated heritability 63.8% (95% CI 49.2–78.4%). The presence of the Panton–Valentine leucocidin (PVL) locus increased the odds of pyomyositis 130-fold (p=10^-17.9). The signal of association mapped both to the PVL-coding sequence and to the sequence immediately upstream. Together these regions explained over 99.9% of heritability (95% CI 93.5–100%). Our results establish staphylococcal pyomyositis, like tetanus and diphtheria, as critically dependent on a single toxin and demonstrate the potential for association studies to identify specific bacterial genes promoting severe human disease.

Certain bacteria that normally live on the skin or in the nose without causing problems can sometimes lead to diseases elsewhere in the body. For example, the bacterium Staphylococcus aureus can cause blood infections or a severe and painful infection of the muscle called pyomyositis, which is very common in children who live in the tropics.

Scientists believe that pyomyositis happens when S. aureus bacteria in the blood stream infect the muscles. Some strains of this bacteria are more likely to cause such infections, but why is unclear. One potential cause is a toxin produced by some S. aureus bacteria called Panton-Valentine leucocidin (PVL). So far, studies looking at whether PVL-producing bacteria are more likely to cause pyomyositis have had conflicting results.

Now, Young et al. show that the gene for PVL is always present in S. aureus strains that cause pyomyosistis in Cambodian children, but is rarely found in S. aureus taken from the noses of their healthy counterparts. In the experiments, bacteria were collected from 101 children with pyomyositis and from the noses of 417 healthy children at the Angkor Hospital for Children in Cambodia over a 5-year period. The DNA in these bacteria were compared using very sensitive genetic techniques. The comparisons showed having the gene for PVL increased the odds of having pyomyositis 130-fold, showing that this one toxin likely accounts for much of the risk of developing this disease.

If more studies confirm the link between PVL and pyomyositis, developing vaccines that block the gene for PVL might be one way to protect children in the tropics from developing this infection. Treating children with pyomyositis with antibiotics that reduce the production of the PVL toxin may also be helpful.

Can a Septic Hip Decision Rule Aid in the Evaluation of Suspected Pediatric Musculoskeletal Infections?

BACKGROUND

Musculoskeletal (MSK) infections can be difficult to diagnose in acute care settings. The utility of clinical decision tools for pediatric MSK infections in an emergency department has not been well studied.

OBJECTIVE

Our aim was to evaluate the performance of a septic hip clinical decision rule (CDR) in the evaluation of pediatric musculoskeletal infections.

METHODS

We performed a retrospective study of children evaluated for an MSK infection in our emergency department from 2014 to 2016. Data collection included demographics, discharge diagnoses, and clinical/laboratory predictors from the CDR. A χ² analysis and Wilcoxon rank-sum tests compared patients with and without MSK infections. Logistic regression analysis examined the predictors for MSK infections. A receiver operating characteristic (ROC) curve was calculated to evaluate the performance of the predictors.

RESULTS

Of 996 evaluations included in the final analysis, 109 (10.9%) had MSK infections. In a multivariable model, an adjusted odds ratio (OR) was significant for fever (OR 3.9, 95% confidence interval [CI] 2.4-6.4), refusal to bear weight/pseudoparalysis (OR 4.4, 95% CI 2.7-7.1), and C-reactive protein (CRP) > 2.0 mg/dL (OR 5.4, 95% CI 3.2-9.1). The probability of infection was 75.1% with five predictors present, 1.9% for zero predictors, and 5.1% if one predictor was present. An ROC curve showed an area under the curve of 0.82, indicating moderate accuracy.

CONCLUSIONS

A septic hip CDR demonstrates a low predicted probability of an MSK infection with zero or one clinical predictor present and moderate predictability with all five predictors. Fever, refusal to bear weight/pseudoparalysis, and CRP > 2.0 mg/dL performed best and should alert providers to consider other MSK infections in addition to septic arthritis.

Acute Hematogenous Osteomyelitis in Children

Background: The epidemiology of acute hematogenous osteomyelitis (AHO) in children has changed. Methods: We reviewed the current literature regarding the epidemiology, microbiology, pathogenesis, clinical presentation, diagnosis, and antimicrobial management of AHO in children. Results: Staphylococcus aureus is the most common microorganism causing pediatric AHO, followed by group A Streptococcus (GAS). AHO due to community-associated methicillin-resistant Staphylococcus aureus (MRSA) can cause severe and complicated disease. Pathogen isolation by culture is key for targeted antibiotic therapy. Polymerase chain reaction assay in tissue sample or joint fluid may enhance the yield of Kingella kingae. C-reactive protein is useful in diagnosis and monitoring the course of AHO. Magnetic resonance imaging is the preferred diagnostic imaging study for AHO. Clindamycin or vancomycin (for serious disease) is recommended for empiric therapy of suspected AHO due to MRSA depending on the geographic prevalence. Penicillinase-stable penicillins or first-generation cephalosporins are preferred antibiotics to treat methicillin-sensitive S aureus (MSSA) infection. Beta-lactam agents are the drugs of choice for treating AHO due to K kingae, GAS, or Streptococcus pneumoniae. For uncomplicated AHO due to MSSA, a short parenteral antibiotic course followed by oral therapy for a minimum total duration of 3-4 weeks is adequate. Complicated AHO due to MRSA may warrant prolonged therapy with surgical intervention. Conclusion: Given the evolution of pathogens, the variability in clinical presentations and course ranging from simple to complex disease, and response to treatment, the management of AHO continues to evolve and warrants an individualized, multidisciplinary approach.

Percutaneous transgluteal computed tomography-guided aspiration of obturator internus pyomyositis in adolescent athlete: A case report and literature review

Pyomyositis is an uncommon infection of muscle that is usually managed conservatively, but, can progress to abscess formation requiring open surgical drainage. We present the first reported case of a 14-year-old male with obturator internus pyomyositis requiring computed tomography-guided percutaneous transgluteal drainage for the management of a right obturator internus abscess. We present this case report to provide an alternative to the open surgical management of abscesses from pyomyositis by means of successful computed tomography-guided drainage.

Fever and Hip Pain: Not Always Due to a Septic Hip

Hip pain in febrile children always raises concern for septic arthritis. Pyomyositis is a rare cause of hip pain. Because it involves muscles around the joint, it may have a similar presentation as a septic hip. This entity therefore has the potential for posing a diagnostic dilemma when physicians face a limping child with fever. We report a child who presented with fever and hip pain and has pyomyositis of the obturator internus muscle. This case underscores the need to consider the possibility of alternative etiologies in a limping child.

Subscapular Abscess Caused by Panton-Valentine Leukocidin-Positive Staphylococcus aureus: An Atypical Presentation

Subscapular abscess is an uncommon condition which requires early recognition followed by prompt surgical intervention. We present a case of spontaneous subscapular abscess following blunt trauma to the shoulder in a patient with a history of recurrent superficial soft tissue infections, in which Panton-Valentine leukocidin-producing S. aureus was identified as the infectious agent. This strain due to its virulence can lead to fatal infections in otherwise healthy individuals; therefore, a high index of suspicion is needed to investigate with an MRI to rule out abscess formation in a patient with acute shoulder girdle pain and negative joint aspirate. Urgent surgical intervention and targeted antimicrobial therapy against PVL-positive S. aureus in accordance with microbiologist yield good outcomes.

Clinics in diagnostic imaging (179). Severe rhabdomyolysis complicated by myonecrosis

A 32-year-old man presented to the emergency department with severe right lower limb pain and swelling of three days' duration. He had multiple prior admissions for recurrent seizures and suicide attempts. Markedly elevated serum creatine kinase levels and urine myoglobinuria were consistent with a diagnosis of rhabdomyolysis. Initial magnetic resonance imaging of the right lower limb revealed diffuse muscle oedema and features of myositis in the gluteal muscles and the adductor, anterior and posterior compartments of the thigh. Follow-up magnetic resonance imaging performed 11 days later showed interval development of areas of myonecrosis and haemorrhage. The causes, clinical presentation and imaging features of rhabdomyolysis are discussed.

Lemierre's Syndrome Presenting as Multifocal Pyomyositis in a Young Child

Lemierre's syndrome is more common in young adults and the majority of patients present with pharyngitis. Multifocal pyomyositis is very rare in this setting and in young children. We present here a case of multifocal pyomyositis caused by Fusobacterium spp. in a young child. Fusobacterium should be considered in the differential diagnosis of multifocal pyomyositis of unclear etiology.

Osteoarticular Infections Caused by Streptococcus pneumoniae in Children in the Post-Pneumococcal Conjugate Vaccine Era

BACKGROUND

Pneumococcal osteoarticular infections (OAIs) are an uncommon manifestation of invasive pneumococcal disease (IPD). We describe the demographic characteristics, hospitalization rate, serotype distribution and antibiotic susceptibility of children with pneumococcal OAI over a 16-year period.

METHODS

We identified patients ≤18 years old with pneumococcal OAI at 8 children's hospitals in the United States (2000-2015). Pneumococcal isolates were collected prospectively. Serotyping and antibiotic susceptibility were performed in a central laboratory.

RESULTS

We identified 97 (3.3%) patients with pneumococcal OAI out of 2943 patients with IPD. Over 60% of the children were <2 years old. Septic arthritis (56.7%, 55/97) was the most common pneumococcal OAI, followed by osteomyelitis (25.8%, 25/97) and septic arthritis with concomitant osteomyelitis (17.5%, 17/97). Hospitalization for pneumococcal OAI overall decreased from 6.8 [95% confidence interval (CI): 5.2-8.6] to 4.4 (95% CI: 3.0-6.3) per 100,000 admissions from 2000-2009 to 2010-2015 (-35%, P = 0.05). Hospitalization for pneumococcal OAI caused by PCV13 serotypes decreased from 4.6 (95% CI: 3.4-6.2) to 0.9 (95% CI: 0.3-1.9) per 100,000 admissions from 2000-2009 to 2010-2015 (-87%, P < 0.0001). Overall, 12% of isolates had a penicillin minimal inhibitory concentration> 2 µg/mL, 3% a ceftriaxone minimal inhibitory concentration> 1 µg/mL and 15% were clindamycin resistant; these proportions remained unchanged after the introduction of PCV13. Serotypes 19A and 35B were responsible for penicillin and ceftriaxone nonsusceptible isolates in 2010-2015.

CONCLUSIONS

Pneumococcal OAI represents 3% of all IPD, affecting mainly healthy infants and young children. Hospitalization for pneumococcal OAI caused by PCV13 serotypes dramatically decreased (-87%) after the introduction of PCV13.

Extensive pyomyositis of vastus muscles

We report a case study on a patient who presented with low back and thigh pain of one month duration. He was eventually diagnosed with left thigh pyomyositis. Tissue from thigh grew Staphylococcus aureus. With commencement of antibiotics and surgical drainage, patient made recovery despite prolonged hospital stay. The underlying mechanism of the extensive abscess accompanied by lack of systemic symptoms; is related to relative immunocompromised state of having underlying diabetes mellitus.

Panton-Valentine Leukocidin Producing Staphylococcus Aureus Facial Pyomyositis Causing Partial Cavernous Sinus Thrombosis

We present a case of subtotal cavernous sinus thrombosis secondary to Panton-Valentine leukocidin-associated Staphylococcus aureus pyomyositis of the muscles of mastication in a previously healthy child, who was successfully managed with no residual disease. He was found to have a factor V Leiden heterozygous mutation. We highlight the propensity of Panton-Valentine leukocidin Staphylococcus aureus to induce venous thrombosis at any site but with potential for more severe consequences in the head. We highlight pyomyositis as a differential for periorbital cellulitis and discuss the significance of the factor V Leiden mutation.