Infectious Myositis Secondary to Multidrug-Resistant Gram Negative Rods in Cancer Patients
Severe infections caused by multidrug-resistant gram negative rods (MDR-GNRs) are increasing healthcare problem worldwide, especially in immunocompromised patients. Infectious myositis is a primary infection of skeletal muscles, usually secondary to gram-positive bacteria, especially Staphylococcus aureus. Although myositis secondary to GNRs are uncommon, several cases secondary to Escherichia coli have been reported in cancer patients. The objective of our study is to describe the microbiological and clinical characteristics of infectious myositis secondary to MDR-GNRs in cancer patients.
From January 2009 to December 2013 we retrospectively reviewed clinical isolates to identify cases of myositis secondary to MDR-GNRs. The diagnosis of infectious myositis was based on clinical presentation (fever and/or pain in the involved muscle), confirmed by compatible radiologic findings and/or muscle biopsy. MDR-GNRs were defined by presence of ESBL or resistance to ≥ 3 of 4 groups (3rd-4th generation cephalosporins, carbapenems, piperacillin/tazobactam and/or quinolones). Resistance to carbapenems alone was also criteria for Carbapenem-Resistant Enterobacteriaceae (CRE) and MDR-Pseudomonas.
17 cases of MDR-GNRs myositis were identified. Median age was 56 (10 - 83), with 14:3 male to female ratio. All patients had hematological malignancies (65% AML) and severe neutropenia, with 59% involvement of lower extremities. E. coli (47%) was the leading cause, followed by Klebsiella pneumonia (24%), Enterobacter species (18%), Pseudomonas aeruginosa (6%) and Stenotrophomonas maltophilia (6%). Among 15 Enterobacteriacea isolates, 27% were CRE and 74% produced ESBL. 88% were diagnosed based on positive blood culture and imaging studies, and the remaining 12% were based on muscle biopsy. 82% received active combination antimicrobial therapy, whereas 18% had active single therapy. None of the patients expired.
Myositis secondary to MDR-GNRs has emerged as a serious problem among neutropenic patients with hematologic malignancy. Awareness of this emerging infection and causative organisms are essential to ensure early and appropriate therapy, to achieve the best possible clinical outcome.
J. Tarrand, None
Z. D. Jiang, None
H. Dupont, None
J. Adachi, None