Increased oxacillin resistance in thigh pyomyositis in diabetic patients

Pyomyositis and Infectious Myositis: A Comprehensive, Single-Center Retrospective Study

Background

Pyomyositis is a bacterial infection of skeletal muscle that classically leads to abscess formation. A related, but distinct, entity is infectious myositis. The epidemiology of these infections has changed in recent years.

Methods

To better characterize both pyomyositis and infectious myositis, we conducted a retrospective study at our tertiary care institution. We identified 43 cases of pyomyositis and 18 cases of infectious myositis treated between January 2012 and May 2020.

Results

The mean age of patients was 48 years, and 66% were male. Diabetes mellitus affected one third of patients, and 16% had other immunocompromising comorbidities. Staphylococcal species accounted for 46% of all infections, and common symptoms included muscle pain (95%) and subjective fever (49%). Altered mental status was a presenting symptom in 16% of cases. Approximately half of all patients received >1 class of antibiotic, and the median length of antimicrobial therapy was 18 days. Open and percutaneous drainage procedures figured prominently in the management of these infections, with 28% of patients requiring multiple procedures. Pathology specimens were available for 12 of 61 cases. Overall, the treatment success rate was 84%.

Conclusions

Gram-positive bacteria accounted for most infections at our institution, and management commonly involved open or percutaneous drainage procedures. Future studies that prospectively evaluate treatment strategies for pyomyositis and infectious myositis are warranted.

Purulent infectious myositis (formerly tropical pyomyositis)

Purulent infectious myositis (PIM), formerly known as tropical pyomyositis, is a pyogenic infection of skeletal muscles. Staphylococcus aureus, a normal human skin inhabitant, is the main pathogen involved, but multiple other microorganisms have been implicated. Although usually a progressive febrile disease with pain in the affected muscle(s), severe, life-threatening forms have been described, especially in immunosuppressed patients and children. PIM may elude early diagnosis given the lack of overlying skin changes. Hence, high index of suspicion followed by imaging modalities (ultrasonography when superficial and computed tomography or magnetic resonance imaging with contrast when deep) help confirm the diagnosis. Treatment requires combination of percutaneous or open surgical drainage along with antimicrobial therapy guided by culture results. The rising incidence of cases due to methicillin-resistant Staphylococcus aureus (MRSA) strains, makes the inclusion of vancomycin be recommended. This paper reviews PIM highlighting its global distribution, causative agents, predisposing factors, management, and potential complications.

Primary pyomyositis in North India: a clinical, microbiological, and outcome study

BACKGROUND/AIMS

Pyomyositis is an infective condition with primary involvement of the skeletal muscles. There is sparse recent literature on patients with pyomyositis.

METHODS

This study was carried out at emergency services of a tertiary care center located in subtropical area of Indian subcontinent.

RESULTS

Sixty-two patients of primary pyomyositis formed the study cohort. Mean age of occurrence was 29.9 ± 14.8 years. There were 54 men. Twelve patients had underlying medical diseases. Muscle pain was seen in all 62 patients. Forty-eight patients (77.4%) had the fever. Most common site of involvement was thigh muscles (n = 29, 46.8%). Forty-nine patients (79%) presented in the suppurative stage of illness. Patients with comorbidities were older (age: median 36 years [interquartile range (IQR), 25 to 47] vs. 24 years [IQR, 16 to 35], p = 0.024), had higher culture positivity with gram-negative organisms (8/9 [88.89%] vs. 6/29 [20.69%], p = 0.001). Importantly, higher number of these patients received inappropriate antibiotics initially. Patients with positive pus culture result had higher complication rate (32/38 [84.21%] vs. 10/18 [55.56%], p = 0.044). Six patients (9.7%) had in-hospital mortality. Lower first-day serum albumin, initial inappropriate antibiotic therapy, and advanced form of the disease at presentation were associated with increased in-hospital mortality.

CONCLUSIONS

Primary pyomyositis is not an uncommon disease entity. Patients with comorbidities were more likely to receive initial inappropriate antibiotic therapy. Patients with positive pus culture report had the higher rate of complications. Lower first-day serum albumin, initial inappropriate antibiotic therapy and advanced form of the disease at presentation were associated with increased in-hospital mortality.

Point-of-care ultrasound in diagnosing pyomyositis: a report of three cases

BACKGROUND

Pyomyositis is a bacterial infection of skeletal muscle that often results in deep intramuscular abscesses. The absence of external dermatologic manifestations in the early stages of pyomyositis makes this a challenging diagnosis. In addition, physical examination findings can be difficult to distinguish from more common processes, such as soft-tissue cellulitis. Clinicians can fail to diagnose this serious disease in a timely manner, resulting in delayed treatment and potential clinical deterioration from sepsis. Although advanced imaging modalities, such as computed tomography (CT) and magnetic resonance imaging (MRI) provide excellent detail, ultrasound (US) can also be used to detect this disease. US can be performed expeditiously at the bedside and is less expensive than CT or MRI. It allows the clinician to examine the deeper tissue planes of muscle, in which purulent fluid collections will develop as pyomyositis advances.

CASE REPORT

Three patients presenting with leg pain were evaluated with point-of-care (POC) US and diagnosed with pyomyositis. The early diagnosis of this condition prompted rapid treatment with administration of appropriate antibiotics and involvement of orthopedic surgery. Aspiration of fluid allowed for detailed fluid analysis and bacterial cultures. Additional diagnostic imaging was performed, confirming the initial US diagnosis. WHY SHOULD AN EMERGENCY PHYSICIAN BE AWARE OF THIS?: POC US can be helpful in identifying and further delineating intramuscular abscesses and can subsequently lead to expedited and appropriate care in patients who present with extremity pain, but lack significant dermatologic changes.

Primary pyomyositis: an unusual presentation in an older patient with no recognised risk factors

Primary pyomyositis is a subacute deep bacterial infection of skeletal muscle. It is typically seen in tropical countries with Staphylococcus aureus being the commonest pathogen. Immunocompromised states and trauma are associated with cases in temperate climates where there is an increasing incidence, typically in children and young adults. However, the authors present a case of primary pyomyositis in a previously healthy 80-year-old female. The authors highlight the potential difficulties in early diagnosis of this rare condition in the UK indicating the need for early MRI imaging and the low sensitivity of blood cultures and serum creatine kinase measurements. Treatment, including early surgical drainage and appropriate antibiotic therapy, is discussed.

Pyomyositis

Pyomyositis is the primary infection of the skeletal muscle. It is common in the tropics, but is increasingly being reported worldwide. It can affect immunocompromised and immunocompetent individuals. Staphylococcus aureus is the most common causative organism. Muscle histology and its culture remain the gold standard for diagnosis. However, among noninvasive methods, MR imaging is highly sensitive and can image large areas of the body and detect subclinical involvement. Early diagnosis, institution of appropriate antibiotic therapy, and drainage of pus lead to favorable outcome.