Sharon M. Dudley

Making a presumptive diagnosis of urinary tract infection by using a urinalysis performed in an on-site laboratory

The purpose of our study was to characterize the utility of certain elements of urinalysis, singly or in combination, in identifying children with urinary tract infections (i.e., positive findings on urine culture). Laboratory results for urine specimens subjected to both urinalysis and culture in an on-site outpatient clinic (office) laboratory during a 36-month period were reviewed. All specimens were collected by one of three methods (the midstream void technique, urethral catheterization, or suprapubic aspiration of urine) from children with symptoms to assist in documenting a possible urinary tract infection. Specimen processing by certified technologists was initiated within 10 minutes of collection. Sensitivity, specificity, and positive and negative predictive values were determined for each test or combination of tests. Of 689 specimens, 102 (14.8%) had positive culture results. The combination of dipstick analysis (leukocyte esterase and nitrite tests) and of microscopic examination for bacteria had a sensitivity of 100% and a negative predictive value of 100%. The nitrite test had a specificity of 100% and a positive predictive value of 100%. We conclude that, when properly collected specimens are evaluated promptly by certified technologists, the rate of accuracy in detecting or ruling out a urinary tract infection (i.e., positive findings on urine culture) with certain elements of the urinalysis is high.

Hospital-acquired urinary tract infections in the pediatric patient: A prospective study

To determine through a prospective study the characteristics of hospital-acquired urinary tract infections (HAUTI) in children, 525 children subjected to bladder catheterization during a hospital admission were identified through surveillance of 12,316 admissions during a 24-month period. Urine culture results were available for 296 (56.4%) of the catheterized patients. In addition 12 noncatheterized children with a documented HAUTI were identified. The clinical courses of all patients with a HAUTI were followed for at least 6 months after their last HAUTI during the study period. Forty-four patients, 1 week to 17 years of age, with 1 or more HAUTI during a hospital unit admission were identified. A total of 51 HAUTI occurred. Thirty-nine (76.5%) of the infections occurred in patients subjected to catheterization. Thirty-two (10.8%) of 296 catheterized patients developed a HAUTI. Forty-three (84.3%) of the 51 infections were single organism infections. One HAUTI was associated with a wound infection with the same organism and one with a concurrent bacteremia with the same organism. Relapses were seen after 4 HAUTI. One reinfection was identified. There were no deaths directly associated with a HAUTI. Hospitalized children subjected to urinary tract catheterization are at significant risk for HAUTI. Complications are infrequent and not life-threatening.

Explanation for false-positive urine cultures obtained by bag technique.

OBJECTIVE To test whether a urine bag technique, previously shown in circumcised male infants 1 month to 1 year of age to yield no false-positive cultures, would give similar results in newborns (females and circumcised and uncircumcised males). DESIGN Prospective study in which periurethral and urine specimens were obtained from healthy newborns. After the periurethral specimen was obtained, the perineum was washed and a urine bag applied. The urine bag was removed immediately after voiding and the urine was cultured. SETTING Normal newborn nursery and pediatric hospital. SUBJECTS Ninety-eight healthy full-term newborns (49 female and 49 male) admitted to the normal nursery during a 4-month period. MAIN RESULTS Isolation of a pathogen from the bag urine reflected periurethral flora. In 20 (95%) of the 21 urine specimens from which a pathogen was isolated, the same pathogen was detected on the periurethra. Sixteen of the 21 urine cultures were falsely positive (> 10(4) colony-forming units of pathogen per milliliter). In 50 (98%) of the 52 urine samples that yielded no growth, the periurethral culture was also negative. In the remaining 25 urine samples in which nonpathogens were detected, the periurethra yielded nonpathogens or no growth. Thus, if a pathogen was isolated from a bag urine sample, the same pathogen was detected on the periurethra 95% of the time. Conversely, if the bag urine sample was negative for a pathogen, the periurethral culture was negative 100% of the time. The presence of a pathogen on the periurethra was more common in female than male neonates (16 of 49 vs four of 49; P = .004), and none of the 14 circumcised male neonates had a pathogen detected on their periurethra or in their urine. CONCLUSION This study explains the finding of false-positive cultures with the bag technique. Pathogens detected in bag urine samples reflected pathogens on the periurethra. Until a bag collection technique that avoids contamination by periurethral flora can be developed, urethral catheterization and suprapubic aspiration remain the methods of choice for obtaining a urine specimen in female and uncircumcised male neonates.

Comparison of three topical antimicrobials for acute bacterial conjunctivitis

One hundred fifty-eight patients, 21 years of age or less, presenting with culture-positive (Haemophilus influenzae or Streptococcus pneumoniae) conjunctivitis were treated with trimethoprim-polymyxin B (TP), gentamicin sulfate (GS) or sodium sulfacetamide (SS) ophthalmic solution for 10 days. Clinical response at 3 to 6 days after start of therapy was similar for all test agents: 26 of 55 (47%) patients cured, 25 of 55 (45%) improved for TP; 28 of 57 (49%) cured, 26 of 57 (46%) improved for GS; and 19 of 46 (41%) cured, 22 of 46 (48%) improved for SS. Clinical response at 2 to 7 days after completion of therapy was also similar: 46 of 55 (84%) patients cured, 5 of 55 (9%) improved for TP; 50 of 57 (88%) cured, 5 of 57 (9%) improved for GS; and 41 of 46 (89%) cured, 2 of 46 (4%) improved for SS. Bacteriologic response at 2 to 7 days after completion of therapy was similar for all antimicrobials: 44 of 55 (83%) patients for TP; 39 of 57 (68%) for GS; and 33 of 46 (72%) for SS.

Use of an Anaerobic Culture Jar in Processing Pediatric Throat Cultures

Two hundred consecutive throat cultures from a Pediatric Walk-in Clinic were processed, using both aerobic and anaerobic culture techniques. The 35 aerobic isolates of group A beta-hemolytic streptococci (BHS) were all confirmed anaerobically as well, and there were two additional isolates detected only by the anaerobic technique. Of these 37 bacitracin-sensitive isolates, only 24 (65%) could be identified at 24 hours using the aerobic technique, compared to 29 (78%) using the anaerobic technique. In contrast to this relatively small effect upon the isolation of group A BHS, the yield of BHS from groups B, C, F, and G was more than doubled by the anaerobic technique. The confusion engendered by the improved detection of these bacitracin-resistant BHS using the anaerobic tech nique offset the small advantage in thoroughness and speed of detection of group A organisms. On this account, until more is known about the possible signaficance of isolating nongroup A BHS in the pharynx, the advisability of using an anaerobic culture jar to process pediatric throat cultures remains uncertain.