Trop Doct 2008;38:254-256
doi:10.1258/td.2008.070425
© 2008 Royal Society of Medicine Press
Case Series and Case Reports |
Pyomyositis mimicking leptospirosis: two cases in a Brazilian tertiary care hospital in a non-tropical area
Letícia Perondi Luz MD
José Miguel Dora MD
Luciano Zubaran Goldani MD
Section of Infectious Diseases and Internal Medicine, Hospital de Clínicas de Porto Alegre, Universidade Federal do Rio Grande do Sul, Ramiro Barcelos 2350, Porto Alegre, RS 90035-002, Brazil
Correspondence to: Luciano Zubaran Goldani, Section of Infectious Diseases and Internal Medicine, Hospital de Clínicas de Porto Alegre, Universidade Federal do Rio Grande do Sul, Ramiro Barcelos 2350, Porto Alegre, RS 90035-002, Brazil Email: Lgoldani{at}ufrgs.br
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SUMMARY
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Pyomyositis is a subacute, deep suppurative bacterial infection
of skeletal muscle not arising from contiguous infection. It
is presumably haematogenous in origin, and characterized by
muscle pain and swelling. We report on two patients who presented
with pyomyositis in a tertiary care hospital in temperate region
located in southern Brazil with a clinical presentation, which
was initially suggestive of leptospirosis. This report discusses
the pathogenesis, clinical presentation, diagnosis and management
of pyomyositis. Physicians living in non-tropical areas should
note that pyomyositis might occur in those areas, and its initial
clinical presentation may be similar to leptospirosis
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Introduction
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Classically, pyomyositis is an infection of the tropics, occurring
in previously active and healthy young men.
1 With increasing
recognition from temperate regions, it is also referred to as
non-tropical myositis, infectious myositis or spontaneous bacterial
myositis.
2,3 Pyomyositis in temperate countries is often regarded
as an infection that occurs in hosts who are immunocompromised
or otherwise debilitated.
We report on two patients who presented with pyomyositis in a tertiary care hospital in a temperate region located in southern Brazil. Their clinical presentation was initially suggestive of leptospirosis. This report discusses the pathogenesis, clinical presentation, diagnosis and management of pyomyositis. Physicians living in non-tropical areas should be aware that pyomyositis might occur in such areas and its initial clinical presentation could be similar to leptospirosis.
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Case history
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Case 1
A 21-year-old white woman presented to the emergency room with
a four-day history of flu-like symptoms, including generalized
myalgias and fever. Examination of the extremities revealed
very painful thighs, calves and the right arm, initially without
oedema, fluctuation, erythema or warmth. Laboratory findings
included a mild anaemia, leucocytes of 11,600 cells/mm
3 (N 84%;
L 11.5%; E 1.1%), aspartate aminotransferase (AST) of 56 IU/L,
alanine aminotransferase of 78 IU/L. As there was the clinical
possibility of leptospirosis, due to the epidemiology and clinical
findings, empiric treatment with intravenous penicillin was
started. A computerized tomography (CT) of the lower extremities
showed several muscle fluid collections on the right and left
thighs, and in the right and left calf muscles. Ultrasound-guided
aspiration of the biggest thigh lesion revealed purulent material.
A culture was positive for oxacillin-sensitive
Staphylococcus aureus. Blood cultures were positive for oxacillin-sensitive
S. aureus. Leptospira testing (microscopic agglutination test)
and HIV antibodies were negative.
The patient improved clinically after antibiotic treatment with oxacillin and ultrasound-guided aspiration of the lesions.
Case 2
A 46-year-old white, previously healthy man presented with a five-day history of fever, myalgias, right back pain, dysuria and dark urine. The patient denied any recent trauma but revealed exposure to rats in his house. Physical examination revealed fever (38°C), mild jaundice, a pulse rate of 102 and blood pressure of 120/70 mmHg. Examination of the extremities revealed tenderness on palpation of the thighs, calves and the right infrascapular area. Laboratory findings included a leukocyte count of 8250 cells/mm3 with 28% bands, serum creatinine of 1.5 mg/dL, serum bilirubin of 4.3 mg/dL, AST of 235 IU/L of 141 IU/L, alkaline phosphatase of 399 IU/L and creatine phosphokinase of 4035 IU/L. Urinalysis revealed 3+ proteins, >100 leucocytes, >50 red blood count. Urine culture grew S. aureus (100,000 colonies/mL) and blood cultures were negative. The patient was started on penicillin for presumptive leptospirosis. Serologies for leptospira, hepatitis A virus and HIV were negative. On day 6, the patient continued to have daily low-grade fever and worsening of right back and thigh pain. On physical examination he presented right infrascapular tenderness and oedema and also thigh tenderness with oedema and induration on palpation. A CT scan showed several muscle fluid collections including the right posterior thoracic wall, gluteal region bilaterally, right anterior thigh and posterior thighs bilaterally. Aspiration of the thoracic collection revealed purulent material and a culture was positive for oxacillin-sensitive S. aureus. The patient improved clinically after antibiotic treatment with intravenous oxacillin and ultrasound-guided aspiration of the muscle abscesses.
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Discussion
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The pathogenesis of pyomyositis is not clearly understood. Diminished
local resistance in the setting of transient bacteraemia is
usually invoked. In a review by Gibson
et al.,
2 predisposing
trauma, including strenuous exercise in healthy persons, occurred
in 50% of cases in the USA and less than 30% of cases in the
tropics. The permissive role of minor muscle damage is suggested
by the numerous reports of pyomyositis after vigorous exercise
and athletic activity in previously healthy individuals in temperate
regions.
4 As observed in our two patients, pyomyositis is most
commonly caused by
S. aureus.
5 Group A streptococci are probably
next in frequency. In addition, multifocal infection affecting
more than one muscle group may be present in 10–20% cases.
6 Pyomyositis is often heralded by local, crampy muscle pain.
Within a few days of onset, the affected muscles become oedematous
and is often described a woody rubbery quality.
7
At this early point, suppuration of the muscle is not yet seen, but mild leukocytosis and low-grade fever may be present. Considering its rarity in non-tropical areas and vague and non-specific clinical presentation, it is unlikely to be considered during an initial diagnosis.8 Despite the fact that our patients complained of severe muscle pain, neither had an initial history of vigorous exercise or predisposing trauma, in addition to the clinical signs of muscle inflammation, oedema, erythema and tenderness. Moreover, the clinical findings - fever, myalgias, mild elevation liver enzymes and creatine kinase serum levels - in both patients were highly suggestive of leptospirosis. It would, therefore, be expected that physicians in this area would begin treatment with penicillin. Although serology testing for leptospirosis was negative for both patients, the diagnosis of leptospirosis cannot be ruled out considering that delayed seroconversions are common, with up to 10% of patients failing to serocovert within 30 days of the clinical onset.
Imaging is the most useful method for diagnosing pyomyositis. Plain radiographs are not sensitive, but in a few cases may suggest muscle enlargement, loss of muscle definition, obliteration of deep fat planes, gas in soft tissues and reactive changes in adjacent bone. CT will often detect muscle swelling and well-delineated areas of fluid attenuation (Figure 1) that display rim enhancement with contrast.9
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Figure 1 Computerized tomography scan of the lower extremities showing several muscle fluid collections on the right and left thighs (a), and the right and left calf muscles (b)
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Physicians living in non-tropical areas should be aware of the
diagnosis of pyomyositis, which could sometimes be initially
confused with other prevalent infectious diseases such as leptospirosis.
Besides antimicrobial therapy, aspiration or surgical drainage
of muscle abscesses are important therapeutic approaches for
the eradication of the infection.
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References
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- Chauhan S, Jain S, Varma S, Chauhan SS. Tropical pyomyositis (myositis tropicans): current perspective. Postgrad Med J 2004;80:267–70[Abstract/Free Full Text]
- Gibson RK, Rosenthal SJ, Lukert BP. Pyomyositis. Increasing recognition in temperate climates. Am J Med 1984;77:788–72
- Harbarth SJ, Lew DP. Pyomyositis as a nontropical disease. Curr Clin Top Infect Dis 1997;17:37–50[Medline]
- Burkhart BG, Hanson KR. Pyomyositis in a 69-year old tennis player. Am J Orthop 2003;32:562–3[Medline]
- Levin MJ, Gardner P, Wldvogel FA. Tropical pyomyositis: an unusual infection due to Staphylococcus aureus. N Engl J Med 1971;284:196–8[Medline]
- Crum NF. Bacterial pyomyositis in the United States. Am J Med 2004;117:420–8[Medline]
- Chiedozi LC. Pyomyositis. Review of 205 cases in 112 patients. Am J Surg 1979;137:255–9[Medline]
- Patel SR, Olenginski TP, Perryquet JL. Pyomyositis: clinical features and predisposing conditions. J Rheumatol 1997;24:1734–8[Medline]
- Struk DW, Munk PL, Lee MJ, Ho SG, Worsley DF. Imaging of soft tissue infections. Radiol Clin North Am 2001;39:277–303[Medline]
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SUMMARY
Introduction
