Prevalence of Proteus species in urinary tract infections in a regional hospital in Trinidad.

BACKGROUND

Proteus bacteria are a well-known cause of urinary tract infections (UTIs). The prevalence of UTIs is high among catheterized patients and those undergoing manipulation of the urinary tract. This study assessed the prevalence of UTIs due to Proteus species, the predisposing factors, complications and extent of antimicrobial resistance at a regional teaching hospital.

METHODS

Urine samples in sterile containers from inpatients and outpatients were inoculated onto cysteine lactose electrolyte deficient agar and sheep blood agar plates with calibrated (0.001 ml) platinum loops and incubated aerobically at 35 degrees C to 37 degrees C for 18 to 24 hours. A colony count of 10(5) bacteria/ml or more was the criterion for significant bacteriuria. Proteus spp were identified and classified into four groups. Susceptibility testing was performed via the Kirby-Bauer disc diffusion technique on Müeller-Hinton agar using ampicillin (10 micrograms), tetracycline (30 micrograms), nalidixic acid (30 micrograms), gentamicin (10 micrograms), nitrofurantoin (30 micrograms), co-trimoxazole (30 micrograms) and cefuroxime (30 micrograms).

RESULTS

Of 1,397 urine specimens from hospital and community patients, 414 had one or more species of bacteria isolated, of which 74 (17.9%) were Proteus spp. Hospital-acquired UTIs accounted for more than two-thirds (51/74, 68.9%) of Proteus spp isolates, while community-acquired UTIs accounted for approximately one-third (23/74, 31.1%) of all Proteus isolates. The prevalence of Proteus UTIs in males was 34 of 184 (18.5%) and was slightly higher than in females (40/230, 17.4%). P mirabilis was the most frequently isolated Proteus sp (55/74, 74.3%), followed by P vulgaris (9/74. 12.2%), Morganella morganii, (7/74, 9.5%) and Providencia rettgeri (3/74, 4.0%). Forty-nine of 55 (89%) P mirabilis isolates were biotype 2. Catheterization was the most common predisposing factor in 32.4% of hospital-acquired Proteus UTIs. More than 92% of Proteus isolates were sensitive to gentamicin and nalidixic acid, whereas, ampicillin (35%) and tetracycline (18%) were the least effective drugs.

CONCLUSIONS

Proteus was isolated from about 18% of patients with significant bacteriuria. Most isolates occurred in hospitalized patients with indwelling urinary catheters and in patients with benign prostatic hypertrophy, diabetes and prostatectomy. Proper catheter care may improve infection control and reduce the morbidity of UTIs associated with Proteus spp.