Evaluation of Chemstrip LN in a male geriatric population

A dipstick method for bacteriologic screening of urine using a combination of leukocyte esterase and nitrite indicators, Chemstrip LN, was evaluated in a male inpatient geriatric population. Three hundred seventy-five urine samples from 198 symptomatic patients (age range, 45 to 98 years; mean, 69.6) were tested by LN and cultured using standard methods. LN showed 169 negatives, but in 7 of these cases, the culture was positive (greater than or equal to 5 X 10(4) col/mL). Organisms recovered from these cultures were Candida (not albicans), Group B Streptococcus, Staphylococcus aureus, and in four cases, Pseudomonas aeruginosa. In the four cases of missed Pseudomonas the patients were receiving aminoglycoside therapy for 2 to 6 days and/or drugs that dye the urine. Despite the fact that many patients were on medications known to interfere with the test strips, the negative predictive value was still 96.0% showing that the strips may be suitable for use with this population given the understanding that certain antibiotics and/or substances that dye the urine may give false negative results.