Acute bacterial parotitis due to methicillin-resistant Staphylococcus aureus.

To The Editor: Acute bacterial parotitis (ABP) is an inflammation of the parotid gland that results from stasis of salivary flow and retrograde bacterial contamination of the Stenson duct. Despite some case reports of Gram-negative (1) and anaerobic bacteria, (2) Staphylococcus aureus remains the most common pathogen of ABP. (3) We report two cases in which methicillin-resistant S aureus (MRSA) was causing ABP, and that support the only two case reports (4,5) previously published in the literature.

A 79-year-old male was admitted to our hospital with right-sided cerebral hemorrhagic infarct. Three days later, the patient developed an extremely painful swelling of the right parotid gland. He had dry oral mucosa, poor dentition, and his oral temperature was 102.8[degrees]F. On examination, his right-sided parotid gland was extremely tender, warm, and swollen. Parotid massage fluid was sent for culture and sensitivity. He was started empirically on intravenous (IV) cefazolin. His parotid gland became more inflamed, and he was transferred to the intensive care unit due to significant inflammatory swelling in the neck, and to monitor his airways. He was treated with IV fluids and high-dose IV dexamethasone. Laboratory data showed a white blood cell count of 15,600 per m[m.sup.3], with 91% neutrophils. Cultures obtained from parotid massage fluid grew MRSA, while blood cultures were negative. Antibiotics were switched from IV cefazolin to IV vancomycin for effective coverage of MRSA.

A 73-year-old male underwent an emergent laparotomy due to acute cholecystitis. He was found to have a ruptured gallbladder intraoperatively, and was started on IV cefazolin postoperatively. On hospital day 10, the patient developed an acute painful swelling of the right parotid gland. His oral temperature was 102.6[degrees]F. The right parotid gland was warm, swollen, and extremely tender, with overlying erythema. Parotid massage fluid was sent for culture and sensitivity. White blood cell count was 24,300 per m[m.sup.3], with 93% neutrophils. Due to the previous case of ABP, he was started on IV vancomycin. A few days later, his parotitis resolved without any sequelae, while parotid massage fluid grew MRSA.

Acute bacterial parotitis is a disease that predominantly affects elderly people who are debilitated with systemic illness or previous surgical procedures. Predisposing factors are advanced age, dehydration, diabetes, human immunodeficiency virus infection, alcoholism, poor oral hygiene, and septic focus in oral cavity. (3) Saliva contains fibronectin, which promotes the adherence of Staphylococcal species to mucous membranes. (3)

In a review of the literature, only two case reports (4,5) including a recent report from Spain, have documented MRSA as a causative organism of ABP. There are few reports documenting Gram-negative, (1) anaerobic (2) and mixed bacteria. Unusual pathogens like salmonella, Pseudomonas pseudomallei, and Treponema pallidum have also been reported rarely, but S aureus remains a leading pathogen, cultured in 50 to 90% cases of ABP. (3)

We stress the importance of obtaining a culture and sensitivity of parotid massage fluid in all cases of ABP. Once the organism in parotid fluid is identified and susceptibility testing is performed, definitive antibiotic therapy should be directed to treat ABP. In view of the emergence of methicillin-resistant strains of S aureus, we emphasize that empirical treatment against MRSA should be considered while awaiting definitive laboratory diagnosis.

References

1. Pruett TL, Simmons RL. Nosocomial gramnegative bacillary parotitis. JAMA 1984;251:252-253.

2. Matlow A, Korentager R, Keystone E, et al. Parotitis due to anaerobic bacteria. Rev Infect Dis 1988;10:420-423.

3. McQuone SJ. Acute viral and bacterial infections of the salivary glands. Otolaryngol Clin North Am 1999;32:793-811.

4. Molina JC, Altes J, Vera R, et al. [Acute bacterial parotiditis due to methicillin-resistant Staphylococcus aureus in the institutionalized elderly]. Enferm Infecc Microbiol Clin 2003;21:325-326.

5. Rousseau P. Acute suppurative parotitis. J Am Geriatr Soc 1990;38:897-898.

Imran Mohammed MD, and Mark Hofstetter MD

Departments of Internal Medicine and Infectious Diseases, Mercy Hospital of Pittsburgh, Pittsburgh, PA