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Temperate pyomyositis in an injecting drug misuser. A difficult diagnosis in a difficult patient
  1. M Crossley
  1. Correspondence to:
 Dr M Crossley, Accident and Emergency Department, Hull Royal Infirmary, Anlaby Road, Hull HU3 2JZ, UK

Abstract

The medical care of injecting drug misusers presents many challenges. Though they can be awkward and unreliable they are at risk of serious medical conditions not often seen in the general population. This case report illustrates some of the difficulties in the diagnosis and treatment of a patient with pyomyositis associated with heroin injection.

  • drug misuse
  • temperate pyomyositis

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A 32 year old man attended the emergency department on the advice of his general practitioner complaining of abdominal pain and vomiting, fresh rectal bleeding, haematuria, and low back pain. He had noticed a swelling on the left side of his lower back, which had become so painful he was barely mobile. He had been injecting heroin for about seven years and had been feeling unwell for two weeks after accidental extravascular injection into his left groin. On closer questioning he admitted to having back pain and requiring elbow crutches to walk for over a year.

On examination he had a temperature of 35.2°C, pulse of 105, respiratory rate of 20, and blood pressure of 100/50. He was dehydrated and looked unwell. He had a fluctuant swelling about 15 cm in diameter on the left side of his lower back, which extended across his sacrum. He was tender over both his greater trochanters. A clinical diagnosis of septicaemia secondary to an abscess was made. As it was not possible to arrange immediate computed tomography the patient was referred to the general surgeons.

The surgical registrar diagnosed septic arthritis involving both hips and sacroiliac joints and advised referral to the orthopaedic surgeons. Orthopaedic opinion was that there was no evidence of septic arthritis in his hips and referred him back to the care of the emergency department. Finally, four hours after arrival, he was admitted to the acute medical ward.

Computed tomography showed a large left sided gluteal abscess (fig 1) communicating through the left sacroiliac joint with the retroperitoneal space (fig 2) and tracking up to the lower pole of the left kidney. Under computed tomographic guidance on day two, two catheters were inserted into the retroperitoneal space and fresh pus drained freely. Blood cultures grew Staphylococcus aureus.

On day 10, repeat computed tomography showed that the abscess, though smaller, contained persistent locules, the left sacroiliac joint remained diastased by pus and there were further locules of pus in the rectospinal musculature. On day 14, he was transferred to the care of the orthopaedic department for open drainage of the abscess and the left sacroiliac joint. He required a further five general anaesthetics for changes of pack and drain removal. On day 64 he was discharged home.

MEDICAL HISTORY

On review of notes it was found that, in the 13 months before this admission, he had attended the emergency department three times and been admitted to hospital twice. He had also been seen in the orthopaedic outpatient department. His initial contact had been an admission, arranged by his general practitioner, when he had a left calf deep venous thrombosis and associated cellulitis. At that time, S aureus was isolated from blood cultures. He was treated with oral flucloxacillin and tinzaparine. He failed to attend for follow up.

Five months later he attended the emergency department with a temperature and low back pain. A diagnosis of psoas abscess was made and he was admitted to the acute medical ward. He absconded from the ward before being seen. The blood cultures that had been taken in the emergency department once again grew S aureus. Attempts made to contact the patient failed as he had lost touch with his family, his phone had been disconnected, and he was no longer registered with a general practitioner. It is interesting to note that the card from this attendance was missing from his emergency department notes, and the blood culture report was filed in the hospital notes only. This information was therefore not available to emergency department staff when he next attended.

Six weeks later he returned to the emergency department complaining of nausea, vomiting, and back pain. He was again admitted under the physicians with a provisional diagnosis of pyelonephritis with muscular back pain. At this stage his haemoglobin was 9.3 g/dl. He subsequently had a normal upper gastrointestinal endoscopy. Once again he developed a deep venous thrombosis. S aureus was again isolated on blood cultures. He was discharged prescribed trimethoprim, flucloxacillin, and warfarin.

After a further six weeks he re-presented to the emergency department with low back pain. His temperature was normal. A diagnosis of muscular pain was once again made. The following week he was seen in the orthopaedic outpatient department, having been referred by his general practitioner for investigation of the persistent low back pain. He was referred for physiotherapy and failed to attend for further follow up.

His next attendance five months later was the episode described initially.

DISCUSSION

Pyomyositis is a primary bacterial infection of skeletal muscle. It is common in the tropics (tropical pyomyositis), first being described by Scriba in 1885.1 It was first reported in the USA in 1971,2 when the term temperate pyomysitis was introduced. Between 1971 and 1986 fewer than 50 cases of temperate pyomyositis were reported.3 With the increasing prevalence of immunocompromised patients and injecting drug misusers it is becoming more widely recognised in temperate countries.4 It is commonly misdiagnosed in its initial stages.5 The most common muscle groups to be involved are iliopsoas (46%), gluteals (18%), and the thigh (18%).6S aureus is the most frequently isolated organism,3,4,6 occurring in over 90% of patients in some series.4 Other organisms implicated include S pyogenes, S freundii, and E coli.3,4,6 Recognised predisposing factors are trauma, HIV infection, diabetes mellitus, corticosteroid treatment, malignancy, and intramuscular injection.

Pyomyositis presents in three stages. Initially there is myositis and muscle oedema but no abscess formation. The patient presents with muscle pain and low grade fever. At this stage the condition may be cured by appropriate antibiotic therapy, but it is difficult to diagnose because of non-specific signs and symptoms.5 The most common stage at presentation is stage two, characterised by abscess formation, muscle pain, fever, tenderness, and leucocytosis. This picture is complicated in stage three disease by systemic toxicity. Treatment in the latter stages requires surgical drainage as well as appropriate antibiotics.6

This case highlights some of the difficulties posed in managing the health needs of drug misusers. It seems probable that the extensive abscesses seen in this patient had been developing over at least 13 months. In this time he had been seen in the hospital on no less than five separate occasions. A combination of factors contributed to the delay in diagnosis. As previously mentioned temperate pyomyositis is often misdiagnosed initially.5 Having been admitted, the patient absconded from the ward, failed to keep follow up appointments, had been removed from his GP’s list, and was at times uncontactable. However, some of the responsibility must rest with the medical teams involved in his care. Incomplete medical records and poor communication between medical specialties, surgical specialties, and the emergency department regarding inpatient investigations and blood cultures resulted in lost opportunities to reinstate appropriate inpatient care.

If the emergency department were to routinely receive and file copies of discharge letters for patients admitted through the department, we would have been aware that on his second admission a diagnosis of psoas abscess had been made, and S aureus had been isolated from blood cultures. This should have enabled him to be rapidly readmitted under the appropriate specialty.

Computer based records should reduce the incidence of notes “going missing” and enable all hospital and perhaps primary care staff to access investigations performed and treatment received by any patient.

It important for all medical staff who may come into contact with injecting drug misusers to be aware of the range of conditions with which they may present and receive adequate training in dealing with patients who refuse treatment. This should result in more timely and appropriate treatment, and ultimately reduce morbidity.

Acknowledgments

With thanks to Dr Richard Lynch for help with the preparation of this article, and to Mr Paul Grout for support with the original idea.

REFERENCES

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Footnotes

  • Funding: none.

  • Conflicts of interest: none.

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