Tropical pyomyositis refers to bacterial infection that affects skeletal muscles causing single or multiple abscesses filled with pus mainly caused by Staphylococcus aureus. This condition is quite common in the tropics and referred to as myositis tropicans, tropical skeletal muscle abscess and tropical myositis; in temperate countries it is referred to as non-tropical myositis, infectious myositis or spontaneous bacterial myositis [1] -[4] . Group B, C and G Streptococcus, pneumococcus, Haemophilus spp., and Gram negative bacilli also cause the condition less commonly compared to Staphylococcus aureus occurring in 90% in tropical and 75% in temperate region. Muscles mostly affected include abdominal, spinal and gluteal muscles, quadriceps, pectoralis major, serratus anterior, biceps, iliopsoas and gastrocnemius [5] [6] . Diagnostic tools such as magnetic resonance imaging, computed tomography and ultrasound are useful. Confirmatory diagnosis is by biopsy or aspiration of pus from affected muscle [7] . Several disadvantages such as pains experienced during regular dressing and delay healing time are associated with incision and drainage technique developed in the treatment of acute abscesses [8] . Later, a technique known as primary closure was also introduced which offers advantage such as preventing secondary infection which is associated with open drains [9] . In the current study, authors seek to find out various parameters in the incision and primary closure with vacuum drainage in the treatment of pyomyositis.

Seventy-seven subjects with pyomyositis were treated using incision, primary closure and drainage under negative pressure wound therapy (NPWT). Of the 77 subjects treated, 58 (75.32%) were males and 19 (24.68%) were females. Ages of patients ranged from 15 to 68 years (Table 1). The length of admission ranged from 5 to 9 days.

Muscles mostly affected included abdominal, spinal and gluteal muscles, quadriceps, pectoralis major, serratus anterior, biceps, iliopsoas and gastrocnemius (Table 2).

Satisfaction rate of wound healing was assessed by patients on a scale of 1 - 5: 1: bad; 2: fair; 3: satisfactory; 4: good, and 5: excellent as shown in Table 3.

Severe wound infection was seen in 3 (3.9%) patients hence therapy was discontinued for them. Table 4 shows the complications during the treatment.

A sample of the patients treated is shown in Figure 1.

This method of incision, drainage, primary closure and the connection of the drainage tube to the negative pressure

wound therapy (NPWT) device (Variant I) provides suitable and preferable cosmetic outcome unlike unsatisfactory cosmetic outcome from the implementation of the incision and wound gauze package only (Variant II). Reduction in the number of dressing changes for Variant I benefits both the nurse who takes care of the wound and the patient with the condition in terms of decrease time as well as the pain experienced during dressing is reduced producing a better outcome for the patient. The primary closure system provides better satisfaction compared to the traditional incision and gauze package technique. Better outcome as a result of patient satisfaction provides relief to patient [11] . Also as has been reported by some authors, the primary closure system with subsequent connection to the NWPT prevents the patient from acquiring any secondary infection. Improved recovery rate implies reduction in hospitalisation and hospital cost. Administration of antibiotics only in the treatment of some abscesses is sometimes inadequate, hence the need for incision and drainage [12] . Incision and drainage often seen as an out-patient procedure is usually carried out in management of abscess or boil to release pus. This procedure may require treatment of the area with antibiotics and aseptically making an incision to allow the pus to drain through the incision. However, because of the possibility of infection, the patient should be treated with antibiotics. The use of the primary closure has been recommended to be beneficial due to its cost effectiveness and not associated with further wound complication. Thus basically this method utilizes negative pressure that promotes wound granulation similar to that obtained from the use of VAC developed by Argenta and Morykwas [13] . The primary wound closure and drainage has been reported to promote faster wound healing and reducing hospital stay. It is also reported to be a safe procedure. A study by Vosa et al. (2012) revealed the implementation of the primary wound closure system is safe and feasible and most importantly does not compromise on mortality thus, giving high survival rates for patients [12] .

In all the patients in our series we used this Variant I procedure only. We did no comparison with the Variant II in our series.

The use of the primary wound closure and vacuum drainage in treating pyomyositis provides patients with much satisfaction, reduction in cost and hospital stay as well as more improved rate of healing and recovery than the former. It is thus more gratifying to the patient and the attendant health professional to use this method.

The authors sincerely thank the numerous nurses and doctors who helped to manage these patients.

No conflict of interests is declared by any of the authors.

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