Int. Med J Vol. 6 No 2 December 2007
PROTEUS MIRABILIS IN STERNOMASTOID ABSCESS: A DOUBLE RARITY
Irfan Mohamad , M Khairi M Daud
Department of Otorhinolaryngology-Head& Neck Surgery, School of Medical Sciences Universiti Sains Malaysia, Kota Bharu, Kelantan, Malaysia
ABSTRACT
Neck abscess is still common in developing countries. Often the presentation is late especially when the pain becomes intolerable or the airway is compromised. Intramuscular abscess in the neck is very rarely encountered. We report a case of an abscess of the right sternocleidomastoid. The culture grew Proteus mirabilis. The outline of management is discussed.
KEYWORDS: abscess, sternocleidomastoid
A 40 year old Malay gentleman was referred from a district hospital with a right neck swelling of one week duration. This was the third episode of similar problem over the previous 10 years.
The swelling started at the right upper neck region with a small painless lump. This grew progressively with accompanying fever and pain over the lump. This was followed by odynophagia and dysphagia.
In the previous two occasions, he underwent incision and drainage, and pus was drained from the lesion.
At admission he was febrile with a temperature of 39 oC. There was a swelling on the right anterolateral aspect of the neck, measuring 6 x 9 cm, firm, tender and warm. The surface was smooth, with no skin changes. There was a healed scar at the most prominent part of the swelling. No area of fluctuation was detected. Intraorally, the right tonsil was pushed medially.
He was started on intravenous cefuraxime and metronidazole and his progress was closely monitored. A sot tissue X-ray of the neck showed a patent upper respiratory tract. Aspiration was done but no pus was aspirated from the swelling.
A CT Scan was done the following day which revealed a ring enhancing hypodense collection within the right sternocleidomastoid, extending from level of styloid process down to the C5 vertebra (Figure 1). The parapharyngeal space was intact. The carotid sheath was compressed but the vessels were patent. A diagnosis of right sternocleidomastoid abscess was made.
Figure 1
An emergency incision and drainage was done and fifty cc of thick foul smelling pus was aspirated from the right sternocleidomastoid. The pus was sent for Acid Fast Bacilli stain, culture and sensitivity. The abscess wall was also sent for histological examination.
Daily dressings were done and the patient was discharged well on day 4 post incision and draining. Proteus mirabilis was isolated from the pus specimen and it was sensitive to cefuroxime. The AFB smear was negative.
DISCUSSION
Neck abscess is a common presentation in ORL clinic. Patients range from a few months old with unknown source of infection to adults with dental caries and the elderly especially those with systemic illness, the commonest being diabetes. In most of the cases, the foci of infection arise from the mucosal surface of the upper aerodigestive tract or carious tooth1.
The site of infection or abscess also varies. It can be in the midline interiorly placed or anterolaterally, superficial or deep. Intramuscularly located abscess is extremely rare.
This patient, presented with a typical history and symptoms of a lateral neck abscess. Fever and neck pain for few days, and odynophagia accompanying the increasing neck lump. In deep neck abscess, dysphagia, drooling of saliva, muffled voice and airway distress are common2.
A CT scan would be able to demonstrate parapharyngeal abscess when there is medialization of the tonsil. This was not present in this case instead there was a right intramuscular sternomastoid abscess.
Computed tomography scan has been the most widely used imaging modality in both children and adult neck infection. It is 90 % sensitive in detecting both deep and lateral neck abscess in children2. However, it is less reliable in differentiating an abscess from cellulitis. CT scan can be misleading especially in the transition stages from cellulitis to abscess3.
The sternomastoid muscle is an extremely rare location for an abscess to be. The source of infection may be from direct spread or haematogenous. The history of multiple incision was done at almost the same site 10 years earlier might explain the possibility of altering the normal architecture of the sternomastoid and the sorrounding anatomy. Intraoperative findings also supported this where upon incision of the skin where there is a thin-walled muscle-like layer through which the pus was pouring out. Previous manipulation and the healing process could have also caused fibrosis and alter the normal anatomy.
Culture of the pus grew Proteus mirabilis. It is rare to isolate Proteus sp in neck infection. Proteus, together with Pseudomonas sp and Escherichia coli only contribute less than 4 % in bacterial isolates of deep neck abscess4. It is part of normal human flora predominantly in the intestinal tract, together with E. coli and Klebsiella sp. Proteus is a gram negative organism and the infection is considered as a community acquired infection.
Conclusion
Sternocleidomastoid muscle is an extremely rare site for an abscess. Previous incision and drainage done to the lateral neck area is most probably the reason for its occurrence. Modern antibiotics and availability of radiological imaging have improved our ability to reduce morbidity and mortality. This case revealed involvement of a rare organism as a cause of an abscess in a rare location.
REFERENCES
1. Annette O Nusbaum, Peter M Som, Micheal A Rothschild, Joel M A Shugar (1999). Recurrence of a deep neck infection. Archives of Otolaryngology- Head & Neck Surgery. 125 (12 ); 1379-1382
2. Lisa M Elden, Kenneth M Grundfast, Gilbert Vezina (2001); The accuracy and usefulness of radiographic assesment in cervical neck infection in children. The Journal of Otolaryngology. 80 (2); 82
3. Welsh LW, Welsh JJ, Gregor FA (1992); Radiographic analysis of deep cervical abscesses. Ann Otol Rhinol Laryngol; 101:854-860
4. Afshin Parhiscar, Gady Har-El (2001); Deep neck abscess :Retrospective review of 210 cases. The Annals of Rhinology, Otology Laryngology.110 ;1051
Correspondence
Irfan Mohamad
Department of Otorhinolaryngology-Head& Neck Surgery,
School of Medical Sciences
Universiti Sains Malaysia,
Kota Bharu, Kelantan,
Malaysia