Escherichia coli Pyomyositis: an emerging infectious disease among patients with hematologic malignancies.
BACKGROUND
Pyomyositis is typically caused by gram-positive bacteria, especially Staphylococcus aureus. Few cases of Escherichia coli pyomyositis have been reported, including only 1 involving a patient with a hematologic malignancy.


METHODS
The clinical microbiology database at The M. D. Anderson Cancer Center (Houston, TX) was reviewed for the period January 2003 through December 2007 to identify cases of E. coli pyomyositis. Clinical characteristics, laboratory and radiologic findings, treatment, and outcomes were recorded. Available isolates underwent phylogenetic group determination, virulence genotyping, multilocus sequence typing, repetitive-element polymerase chain reaction, and pulsed-field gel electrophoresis.


RESULTS
Six cases of E. coli pyomyositis were identified. All patients were receiving chemotherapy for a hematologic malignancy; 5 were severely neutropenic. Three patients became hypotensive, 2 required intensive care, and 2 (33%) died, despite receiving carbapenem therapy. All E. coli isolates were fluoroquinolone resistant; 55% produced an extended-spectrum beta-lactamase (ESBL). Five of 6 available isolates belonged to phylogenetic group B2, had similar virulence factor profiles, exhibited > 95% similar repetitive-element polymerase chain reaction profiles, and represented sequence type ST131; however, all had unique pulsed-field gel electrophoresis profiles.


CONCLUSIONS
E. coli pyomyositis has emerged as a serious problem among our patients with hematologic malignancy. It usually is caused by members of E. coli ST131, a recently identified cause of fluoroquinolone-resistant, ESBL-positive E. coli infection worldwide. Awareness of this emerging syndrome and the usual causative agent is important to ensure appropriate management when febrile, neutropenic patients with hematologic malignancy exhibit signs of localized muscle infection.
Vigil
Karen J
KJ
The University of Texas-M. D. Anderson Cancer Center, 1515 Holcombe Blvd, Unit 1460, Houston, TX 77030, USA.
Johnson
James R
JR
Johnston
Brian D
BD
Kontoyiannis
Dimitrios P
DP
Mulanovich
Victor E
VE
Raad
Issam I
II
Dupont
Herbert L
HL
Adachi
Javier A
JA
D000328:Adult; D000368:Aged; D000900:Anti-Bacterial Agents / Q000494:pharmacology; D015373:Bacterial Typing Techniques; D016000:Cluster Analysis; D021821:Communicable Diseases, Emerging / Q000188:drug therapy / Q000453:epidemiology* / Q000382:microbiology / Q000473:pathology; D016172:DNA Fingerprinting; D024881:Drug Resistance, Bacterial; D016521:Electrophoresis, Gel, Pulsed-Field; D004926:Escherichia coli / Q000145:classification / Q000302:isolation & purification; D004927:Escherichia coli Infections / Q000175:diagnosis / Q000188:drug therapy / Q000453:epidemiology* / Q000473:pathology; D029968:Escherichia coli Proteins / Q000235:genetics; D005260:Female; D024841:Fluoroquinolones / Q000494:pharmacology; D005838:Genotype; D019337:Hematologic Neoplasms / Q000150:complications*; D006801:Humans; D020071:Interspersed Repetitive Sequences; D008297:Male; D008875:Middle Aged; D017720:Molecular Epidemiology; D016133:Polymerase Chain Reaction; D052880:Pyomyositis / Q000188:drug therapy / Q000453:epidemiology* / Q000382:microbiology / Q000473:pathology; D012189:Retrospective Studies; D017422:Sequence Analysis, DNA; D037521:Virulence Factors / Q000235:genetics
D000900:Anti-Bacterial Agents; D029968:Escherichia coli Proteins; D024841:Fluoroquinolones; D037521:Virulence Factors