Infective endocarditis due to Providencia stuartii.

To the Editor: Infective endocarditis (IE) is a common and, if untreated, a uniformly fatal disease. The incidence of IE continues to rise, with a yearly incidence of about 15,000 to 20,000 new cases. (1) Moreover, the incidence of IE is about 1 per 1,000 hospital admissions, with infected patients having a mean age of 50 years. (2) The main pathogens are Staphylococcus aureus, Viridans streptococci, and Enterococcus. (2-4) We describe a case of IE in a nursing home resident due to an uncommonly encountered agent, Providencia stuartii.

The patient was a 69-year-old male with a chronic indwelling Foley catheter who complained of subjective fever, chills, anorexia, and severe fatigue. He was acutely ill, appearing emaciated, with a blood pressure of 78/40 mm Hg, heart rate of 90 bpm, respiration rate of 20 per minute and a temperature of 94.7[degrees]F. Heart and lung examinations were normal. Stage IV decubital ulceration was present on the left hip. White blood cell count was 18.6 X [10.sup.9]/L (94.6% segmented neutrophils). Urinalysis was positive for leukocyte esterase, nitrates, and for leukocytes. Multiple and repeated sets of blood and urine cultures subsequently returned positive for Providencia stuartii. Transthoracic echocardiogram demonstrated an obvious, chaotic, oscillating mass on the mitral valve.

The diagnosis of endocarditis caused by P stuartii was based upon the presence of two of the Duke major criteria (5) of persistent bacteremia separated by greater than twelve hours and an oscillating mass on the mitral valve. Although the presence of P stuartii is well documented in urine samples of patients with chronic indwelling catheters, and in surgical wounds, feces, blood cultures in nursing home patients, water samples, burn units, and even in pediatric sepsis cases, the occurrence of endocarditis due to this pathogen has not been reported to our knowledge.

According to the current classification, there are five species in the genus Providencia (5), namely P alcalifaciens, P heimbachae, P rettgeri, P rustigianii, and P stuartii. The medical significance of P stuartii has usually been confined to nursing home patients with a chronic indwelling bladder catheter. Bacteria seldom considered to be uropathogens in noncatheterized patients are found commonly in the urine of long-term-catheterized patients. P stuartii is a classic unfamiliar pathogen that occurs frequently in the urine of patients with a chronic indwelling catheter.

In summary, while the endocarditis-associated classic Gram negative bacteria, HACEK (an acronym that refers to Haemophilus species, Actinobacillus actinomycetemcomitans, Cardiobacterium hominis, Eikenella corrodens, and Kingella species) and Pseudomonas aeruginosa have been well documented, the emergence of Providencia stuartii as a source of endocarditis has not been established. Given the frequency of its appearance in the urine samples of nursing home patients, particularly those with chronic indwelling catheters, perhaps the incidence of this pathogen causing endocarditis is higher than otherwise thought. The endocarditis could be easily missed in elderly patients due to their inability to mount a febrile reaction, difficulty obtaining a history, and perhaps the attribution of a murmur to a chronic cardiac condition. Moreover, the overall constellation of signs and symptoms could easily be assigned to urosepsis.

References

1. Bayer AS, Bolger AF, Taubert KA, et al. Diagnosis and management of infective endocarditis and its complications. Circulation 1998;98:2936-2948.

2. Hoesley CJ, Cobbs CG. Endocarditis at the millennium. Journal Infect Dis 1999;179(Suppl 2):S360-365.

3. Eykyn SJ. Endocarditis: basics. Heart 2001;86:476-480.

4. Alestig K, Hogevik H, Olaison L. Infective endocarditis: a diagnostic and therapeutic challenge for the new millennium. Scand J Infect Dis. 2000;32:343-356.

5. Durack DT, Lukes AS, Bright DK. New criteria for diagnosis of infective endocarditis: utilization of specific echocardiographic findings. Am J Med 1994;96:200-209.

Patrick R. Krake, MD

Neeraj Tandon, MD

Department of Medicine, Section of Cardiology, Louisiana State University Health Sciences Center-Shreveport, Shreveport, LA