MRSA infection of masticatory spaces in a paediatric patient

Background

Fascial space infections are the common sequelae of the infections arising from teeth or the periodontium or the pericoronal tissues.1 Once these infections breach the confines of the cortical bone of the jaws, it results in the involvement of superficial and deep fascial spaces, commonly manifesting as facial swelling. If left untreated, these fascial infections can have serious complications like airway compromise due to Ludwig’s angina, descending necrotising mediastinitis, cavernous sinus thrombosis or brain abscess.2

In children, the diagnosis of the source of infection is challenging due to variable presentation, difficulty in eliciting a thorough history and multiple potential non-odontogenic source of infections. The involvement of masticatory spaces like pterygomandibular space does not manifest as significant facial swelling. Rather, it has a classic presentation of severely restricted mouth opening, which can further complicate the diagnosis. This delay in diagnosis and treatment in a paediatric patient leads to dehydration and early onset of systemic sepsis.3

Additionally, there have been increasing reports of methicillin-resistant Staphylococcus aureus (MRSA) infection in the oral cavity. Recent studies have shown that MRSA infection is not limited to hospital-acquired settings, and there have been cases of community-acquired MRSA infections of the skin and soft tissues. Owing to the high degree of morbidity and mortality associated with MRSA infection, it is essential to have an early diagnosis and start prompt treatment.

Herein, the authors report a clinical case that is unique in a few aspects, including the involvement of masticatory space, primarily a paediatric patient and isolation of MRSA microorganism from the site of infection. With this case, the authors want to emphasise the methods to form an early diagnosis so that appropriate treatment is started at the earliest, minimising the risk of complications.

Case presentation

An otherwise healthy 9-year-old girl reported to our hospital with swelling on the right side of the face for 2 weeks. History revealed that the patient resented with pain with respect to lower right deciduous molars and reported to a local hospital for the same. The patient was diagnosed with decayed deciduous molars and subsequently underwent extraction of the involved teeth 1 week ago and was discharged with oral antibiotics and analgesics. However, the patient noticed an increase in the swelling and pain over a period next 1 week. The patient then reported to our centre for further investigation and definitive management.

On extraoral examination, facial asymmetry was noted due to diffuse swelling of the right side of mid-face, which was tender on palpation with a local rise of temperature. The swelling extended from angle of the mandible to 1 cm posterior to the angle of mouth; however, the lower mandibular border was palpable (figure 1). Besides, the right submandibular lymph nodes were palpable and tender. Mouth opening was severely restricted to 6 mm, so a thorough intraoral examination could not be carried out. However, there was no swelling in the floor of the mouth with minimal obliteration of the right lower buccal vestibule.

Figure 1

Extraoral photograph depicting diffuse oedema of the right of face extending from angle of mouth to approximately 1 cm posterior to the right corner of mouth.

Investigations

At the time of presentation, the patient’s primary complaint was pain and severely restricted mouth opening. In the first examination, patient was afebrile, normotensive, but with mild tachycardia. A paediatric consultation was sought for an opinion regarding empiric antibiotherapy and fluid resuscitation. Initial laboratory workup showed mild leucocytosis to 14.8×10³/mL with a left shift of neutrophil count.

Based on the history and clinical examination, a provisional diagnosis of right masticatory space infection was made. An orthopantomogram was advised as a screening X-ray, which did not reveal any significant finding. Developing right lower premolars with open apices were noted with no remnant root piece of the extracted deciduous molars (figure 2). A contrast-based CT scan was done to define the extent of swelling and localise the collection, if any. On evaluation of the CT scan by the radiologist, ill-defined lytic areas were noted involving the right ramus of mandible with few breaches in medial and lateral cortices. An adjacent hypodense collection measuring approximately 3.8×3.1×4.1 cm was noted along the medial and lateral aspect of the ramus with involvement of masticator spaces (figures 3 and 4).

Figure 2

Orthopantamogram did not reveal any significant sign of infection of the right mandibular region. They were developing succedaneous tooth in the relation of lower right second premolar underlying the extracted lower right deciduous first molar.

Figure 3

Coronal view of contrast-enhanced CT of the face shows hypodense collection on medial and lateral aspect of right ramus, suggestive of masticator space infection.

Figure 4

Axial view of contrast-enhanced CT of the face shows similar findings of right masticatory space infection. Adjacent inflammatory changes in the form of fat stranding can also be appreciated.

Differential diagnosis

Based on the clinical findings and correlation with the results of CT scan, diagnosis of right masticatory space infection with involvement of right submasseteric space and right pterygomandibular space was made. The space infection was attributed to being of odontogenic origin based on the history of teeth decay and extraction of the same.

Treatment

The patient was taken up for incision and drainage of the right submasseteric and right pterygomandibular space under general anaesthesia. Initially, a mouth gag was used to open the mouth forcefully. A vertical incision was given along the ascending ramus and blunt dissection done to reach the lateral ramus. The submasseteric space was reached using moult periosteal elevator and sinus forceps, which resulted in a spontaneous release of pus (figure 5). The pus samples were taken in swabs and sent for culture and sensitivity.

Figure 5

Intraoperative view shows oozing of pus from the right pterygomandibular space after it was approached via an incision placed along the anterior border of ascending ramus.

Similarly, the pterygomandibular space was explored through the same incision, while staying medial to the ramus. Minimal pus collection was noted in the pterygomandibular space. After thorough debridement, corrugated rubber drains were secured to both the spaces. Intraoperatively, maximal mouth opening of 28 mm was observed.

After the surgery, the patient was started on empirical antibiotic therapy of amoxicillin–clavulanic acid, metronidazole and gentamycin. After 48 hours, the culture and sensitivity report showed the presence of MRSA. Based on the sensitivity report, the patient was started on intravenous clindamycin (300 mg bd) for a total duration of 5 days. Regular debridement of the surgical site was done through the drains for 4 days. Also, a rigorous mouth opening exercise was done regularly.

With the regular debridement, physiotherapy and antibiotic therapy as per the culture-sensitivity report, there was significant improvement in the mouth opening along with resolution of infection symptoms. Once the drain site did not show any collection for the 24-hour period, the drains were removed, and the site closed.

Outcome and follow-up

The patient was discharged after 7 days and was continued on oral antibiotics (clindamycin) for another 3 days and was advised regarding mouth opening exercises. On 10-day follow-up, the patient showed significant improvement in mouth opening (maximal mouth opening of 25 mm) and complete resolution of the infection (figure 6)

Figure 6

One-week postoperative follow-up picture shows an acceptable mouth opening of 25 mm with the resolution of infection.