A case report and review on sternal osteomyelitis

Vijayakumari. D1, Shalini H S2, Varunkumar3, Muralidhar T R4

1Nurse Educator, Kauvery Hospital, Electronic City, Bangalore

2CNO, Kauvery Hospital, Electronic City, Bangalore

3Asst Operation Manager, Kauvery Hospital, Electronic City, Bangalore

4Head of Department – Critical Care & ICU, Kauvery Hospital, Electronic City, Bangalore

Abstract

Introduction

Sternal osteomyelitis usually presents with chest pain, fever, tenderness, and swelling. However, some of these signs and symptoms might not be present and sternal osteomyelitis may be confused with other cardiac and pulmonary conditions. Since sternal osteomyelitis is not common, it can be initially misdiagnosed, thus delaying its management. Radiological imaging, microbiology testing and other laboratory modules help diagnose suspected cases of osteomyelitis. CT and MRI are currently considered the standard for diagnosing osteomyelitis. The most common bacterial cause of sternal osteomyelitis is Staphylococcus aureus, meanwhile Pseudomonas aeruginosa is common in IV drug users. Treatment of sternal osteomyelitis can be initiated after identifying the causative microorganism, which is determined by blood culture or direct bone biopsy. Antibiotics are the primary treatment of sternal osteomyelitis, but with the addition of surgical debridement, antibiotic treatment has been proven to be more efficacious. Surgical intervention is necessary in cases where antibiotic treatment alone has failed or when abscesses and extensive bone necrosis are present.

Introduction

Sternal osteomyelitis remains a rare but morbid and challenging condition. Due to the limited reports of Sternal Osteomyelitis in the literature, management of this disease continues to lack consensus.

We present a case report highlighting how SO remained, in our experience, refractory to medical management, and how operative intervention provided resolution, and a review of the literature.

Most cases of sternal osteomyelitis are secondary, related to median sternotomy.

Risk factors include intravenous drug use, diabetes, and obesity but our cases with no apparent risk factors have been documented. This presents a challenge for both the diagnosis and treatment of this condition. Most cases are treated with either antibiotic therapy alone or antibiotics with debridement and closure or soft tissue reconstruction with vascularized flap coverage.

The aim of this report is to highlight a unique case of SO, treatment strategy, and overview of current state of this condition in the literature.

Case Presentation

A 63 years-old male patient presented to emergency department with the history of fever, decreased urine output generalized weakness& altered sensorium in the last 2 days. Patient had comorbidities of Diabetes Mellitus & Hypertension.

Patient had undergone CABG+ AVR.

On assessment patient was drowsy, not obeying commands & GCS Score is E4M5V2, Pupils reacting to 2mm. Additionally patient had metabolic acidosis, increased lactate level & hypotension.

Clinical Examination

GRBS – 132 mg/dl

Pulse – 107/Bpm, BP- 150/ 130 mm of Hg, later 100/60, RR- 24/Bpm, Temp-99, SpO2-96 % on RA

RS – Bilateral Air entry +, CVS- S1, S2 + No murmur, Abdomen- Soft & Non-tender, No Organomegaly

CNS – E4V2M5, Pupils- 2mm bilaterally reactive to light, Power- 5/5 all four limbs

Diagnosis & Clinical Evaluation

In ER, IV line secured & prescribed medication, iv fluids were given. ER consultant advised for ICU admission & attenders were counselled on the same. Blood culture & Blood sample collected & send to lab for report and patient shifted to ICU for further Management. On admission a parenteral antibiotic was started empirically

He was evaluated with CT brain which showed wedge shaped hypo densities in the cortical and subcortical white matter of left frontal, parietal lobes with effaced sulcus spaces looks like acute infract (CVA -Cardio Embolic Stroke). Patient was managed with IV Fluids, antibiotics, anticoagulants, anti-epileptics, glycaemic agents, nebulization, antihypertensive & supportive medicines.

Sent Blood culture to rule out Infective Endocarditis & HRCT was done. HRCT showed ground glass attenuation in the dependent segments of bilateral lower lobes with small interstitial thickening

Cardiologist Reference was obtained.  Echo showed No RWMA, EF-50%.

In view of deranged renal parameters Nephrologist reference was obtained and advised followed.

CTVS reference was obtained in view of post CABG+ AVR status. Serial monitoring of CBC was done.

Gradually total count increased to 25860 and patient developed post CABG wound dehiscence. Plastic surgeon reference was obtained for the sternal osteomyelitis.

Laboratory Investigation Details

Early investigations revealed leucocytosis with white blood cell count of 21400 (Normal range: 4000-11000)

Date 09/0610/0611/0612/0613/0616/0619/0620/0621/06
Total Count214001376013300131601083017060251502336025860
Haemoglobin10.49.38.68.69.19.98.48.27.8
Platelet Count323k291k320k288k246k332k298k320k329k
Creatinine2.21.51.10.90.60.50.50.5-
Date22/0623/0624/0625/0626/0627/0702/0704/07
Total Count22720153501076075607080700076908390
Haemoglobin8.48.19.39.69.59.210.610.3
Platelet Count285k262k197k185k177k167k254k275k
Creatinine0.6-0.5-0.5-0.5

Graphical representation shows the variations of white blood cell count been monitored from admission to discharge of the patient.

Culture Details

DateName of the CultureOrganismsSensitivity ReportAntibioticsChange of Antibiotics
09-JunBlood CultureStaphylococcus Aureus (MRSA)Inj. Meropenem 500 mg
Urine CultureNo Growth
10-JunUrine CultureNo GrowthGentamicin 4.0; Tetracycline <=1.0; Erythromycin <=0.25; Linezolid 2.0; Cotrimoxazole 2.0Inj. Teicoplanin 400 mgInj. Meropenem 500 mg – 1 g; Inj. Fluconazole 200 mg
Blood CultureStaphylococcus Aureus (MRSA)
14-JunUrine CultureNo Growth Inj. Vancomycin 1 g
Blood Culture Right HandNo Growth
Blood Culture Left HandNo Growth
18-JunPus CultureAcinetobacter Baumannii (MDR)Colistin <=0.5 (Intermediate)
19-JunUrine CultureTrichosporon Asahii
21-JunPus CultureNo Growth
23-JunTissue CulturePseudomonas AeruginosaImipenem 2.0; Meropenem 0.5; Aztreonam 0.5; Piptaz <=4.0; Ceftazidime 2.0; Cefoperazone-Sulbactam <=8.0; Cefepime 8.0; Amikacin 4.0; Ciprofloxacin 0.5; Levofloxacin 1.0 Tab. Levofloxacin 400 mg
27-JunBlood CultureNo Growth
04-JulBlood CultureNo Growth
Urine CultureNo Growth

Patient was initially started on intravenous empirical antibiotic therapy with inj. Meropenem 500mg & Inj. Teicoplanin 400 mg. Following the confirmation of both blood & pus cultures, the antibiotic regimen was adjusted based on the sensitivity report. The patient was transitioned to Inj. Flucan 200 mg & continued with inj. Meropenem 1 gm to ensure the adequate course of treatment.

Radiology Investigations Reports

Chest X-ray Reports

A chest Xray was performed Initially & showed mild cardiomegaly. A follow up Xray was performed after the initial treatment showed normal.

X Ray on follow up

  • Xray showed  normal cardiac contours
  • Bilateral lung fields clear
  • Sternotomy sutures in situ

X Ray after procedure

  • Sternotomy sutures noted in situ
  • Both CP Angles appear free

X Ray before Discharge

  • X-ray was done before discharge.
  • X-ray showed No radiological significant abnormality

CT Reports

In view of the diagnostic uncertainty, a computed tomography (CT scan) was quickly performed to find the exact causes of the condition.

The Scan showed that ground glass attenuations in the dependent segments of bilateral lower lobes with interstitial thickening. Cardiac Contour: Status sternotomy. Cardiac prosthetic valve.

Report at after the procedure

CT showed that dehiscence across the mid & lower sternum (predominantly at the xiphisternal level) with peripherally enehancing fluid in the intersternal/presternal spaces all along its length with cortical irregularity- Likely Osteomyelitis changes.

Soft tissue thickening in the retrosternal space abuts the anterior pericardium at the atrioventricular junction.

CT Report at before discharge

CT Showed that small subpleural interstitial thickening in bilateral posterior basal segments.

Permeative osteolysis along manubrium and sternal bones -? Osteomyelitis. The inner cortex appears intact.

Loculated collection in the outer margin of the left pectoralis major, minor along the muscular plane

Post op Care

In view of sternal osteomyelitis patient underwent Wound Debridement with VAC dressing under General Anaesthesia. Large amount of seropurulent fluid was drained, debridement of all necrotic area was done. A vacuum dressing applied. Wound culture sample sent to lab for the report. Post operatively patient shifted to ICU care with ventilator support. Patient was managed conservatively, and he was extubated & slowly weaned off from the ventilator. Patient was stabilized in the ICU & patient shifted to ward for further treatment.

Wound culture showed growth of Pseudomonas sensitive to levofloxacin. Levofloxacin regimen started accordingly. Patient had a fluid collection on the debridement site. Plastic Surgeon was seen the patient & patient taken for wound debridement.

Procedure 1: Wound Debridement under GA

Findings & Procedures

Under GA sternotomy wound visualized

The sternotomy necrotic wound debridement done & SS wire loss

All 3 ss wire removed

Bone edges freshened & VAC reapplied

Plan for flap cover in 5-6 days

Procedure 2: Debridement left pectoralis major mass flap with skin & advanced flap cover under GA

Findings and Procedures

Under GA Sternal wound debrided

Diligence vivo edge Rissler the defect between sternal edge filling Willi pectoralis major flap for left side and wound covered with skin advanced flap equal side.

Endocrinology, Neurology, cardiology Nephrology & CTVS review was taken for follow up care & medicines optimized accordingly. Patient was managed with compression dressing, antibiotics, analgesics and other supportive management.

Presently patient neurological status GCS E4V3M6 right hemiparesis persist power 2/5. He is haemodynamically stable, ambulated to bed to chair. Patient is discharged with subcutaneous drain in the sternal site.

Surgery Images

Discussion

Sternal osteomyelitis usually happens after external bacterium seeds sternum bone where it begins to grow and thrive, leading to destruction and pus accumulation under periosteum. Identifying the causative agent is critical for choosing IV antibiotics. In 2022 a review by Cha, Y. K., Et al. found that Staphylococcus was the most common organism in sternal wound cultures. Our patient’s sternum was infected with Staphylococcus aureus despite treatment with antibiotics.

The diagnosis of sternal osteomyelitis is based on clinical presentation, radiologic imaging, laboratory, and microbiological findings. However, the diagnosis is usually delayed due to few reported cases and nonspecific clinical presentation

There is no consensus on the standards of care for sternal osteomyelitis because of the limited literature discussing this topic. Management differs depending on the clinical presentation, whether the sternal infection is superficial or deep, and culture results. However, the basic principles of treatment usually include antibiotics, drainage of pus, surgical debridement of necrotic tissue, and different closure techniques. Antibiotics, specifically that cover Staphylococcus aureus, are usually enough to treat sternal osteomyelitis. However, surgical intervention is necessary in cases where antibiotic treatment alone has failed or when abscesses and extensive bone necrosis are present. Early surgical intervention usually ensures definitive treatment, decreases morbidity, and is more cost-effective. The surgical management usually include complete debridement of the infected bone and the anterior periosteum. The anterior bone defect is generally covered with a vascularized muscle flap while the posterior periosteum is kept facilitating osteogenesis and sternal healing. Vacuum-associated dressing is applied to remove exudate, accelerate wound healing and is associated with better outcomes. Treatment failure can cause mediastinitis, abscess collection, chronic infection, fistulae, and sinus tracts formation. In our case, the patient was treated with surgical drainage of chest wall abscess, was put on Meropenem – Vancomycin, Fluconazole & Levofloxacin, underwent multiple debridement procedures, and was put on vacuum dressing.

We emphasize the importance of early detection and optimum treatment of patients with sternal osteomyelitis to avoid complications. Broad spectrum empirical antibiotic regimen should be used, covering both gram-negative and gram-positive organisms, in order to avoid reinfection of the wound with other organisms.

Conclusion

Sternal osteomyelitis can have a nonspecific clinical presentation like fever, chills, chest pain, a painful chest mass. Tenderness, swelling, decreased urine output & altered sensorium. Several imaging modalities can be instrumental in diagnosing sternal osteomyelitis.  Chest Xray is typically the initial imaging modality. However, it may reveal only the soft tissue swelling. Both Computed tomography & Magnetic Resonance Imaging offer higher sensitivity & specificity for diagnosing this case. These imaging modalities provided the accurate & detailed characterization of the affected area. Blood culture & pus culture was sent to identify the causative organisms & Empirical antibiotic therapy was stared. The patient was closely monitored & clinical improvement was observed with gradual resolution of symptoms.

This case highlights the importance of early recognition and a comprehensive approach to treatment, which includes targeted antibiotic therapy, inotropes, surgical drainage & Supportive Management. Early Laboratory investigations and radiological findings are crucial for a prompt diagnosis. To prevent the progression of the disease and complications, early intervention is vital to ensure a good prognosis.

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