Comparison of throat culture methods for the recovery of group A streptococci in a pediatric office setting.

OBJECTIVE: To compare a single-plate method for the recovery of group A streptococci with other methods that have recently been reported as being significantly more sensitive. DESIGN: Throat swabs were allowed to dry for 2 to 6 hours before inoculating 5% sheep blood agar plates. Stabs were made into the agar, bacitracin disks were placed on the primary plates, and the cultures were incubated aerobically. Using duplicate throat swabs, the recovery rates of the above method were compared with the following ones: a carbon dioxide-enhanced incubation atmosphere, an anaerobic atmosphere with a selective blood agar medium, and a Todd-Hewitt broth medium. SETTING: A five-pediatrician office. PATIENTS: A total of 301 pediatric patients with pharyngitis were evaluated using all comparative methods. In addition, duplicate swabs from 590 pediatric patients were compared with each other using the same single-plate method. RESULTS: There were no significant differences between any of the methods. The sensitivity of the single-plate method compared with selective plates incubated anaerobically was 96%. CONCLUSIONS: In a pediatric office setting, a single-plate method using aerobic incubation was adequately sensitive for the recovery of group A beta-hemolytic streptococci. Transport medium, selective medium, carbon dioxide enhancement, and anaerobic incubation did not significantly improve recovery. The present federal regulations that restrict the use of nonselective media and bacitracin disks on primary plates should be reevaluated.

Comparison of an optical immunoassay technique with two culture methods for the detection of group A streptococci in a pediatric office.

For detecting group A beta-hemolytic streptococci in an office setting, an optical immunoassay method was compared with two culture methods. The sensitivity and specificity of OIA as compared with 5% sheep blood agar cultures were 91.4% and 95.6%, and as compared with a Todd-Hewitt broth method were 90.4% and 94.1%, respectively.

Tetrasomy 9p: tissue-limited idic(9p) in a child with mild manifestations and a normal CVS result. Report and review.

Supernumerary isochromosomes resulting in autosomal tetrasomy are rare and have been described only for 12p, 18p, and 9p. Nineteen previous cases of tetrasomy 9p have been reported, and in 6 cases, tissue-specific mosaicism was implied with the i(9p) cell line present exclusively or predominantly in blood. We report on an infant who had apparently normal chromosomes (46,XY) on CVS. He was referred for genetic evaluation because of mild developmental delay and minor anomalies. In 75% of blood cells he had an extra isodicentric 9p chromosome (pter-->q12-->pter). The interpretation of tetrasomy 9p was confirmed by elevated GALT activity. No tetrasomy 9p cells were seen in 100 skin fibroblasts. This case demonstrates the tissue specific mosaicism in tetrasomy 9p which rendered the anomaly undetectable by CVS. It also demonstrates the mild end of the clinical spectrum associated with tetrasomy 9p.

Comparison of immediate and delayed culture methods for isolation of group A streptococci.

Recovery rates of Group A beta-hemolytic streptococci in throat cultures from 300 children were studied using three different methods. The swabs were streaked onto plates immediately, streaked from the same dry swabs held at room temperature for 3 to 6 hours and streaked from swabs held in transport media at room temperature for 3 to 6 hours. The cultures were processed in a pediatric office and interpreted by a microbiologist. The recovery rates were similar for the three methods, but the cultures were easier to interpret when the swabs had been allowed to dry before streaking as a result of a decrease in the normal flora on these plates. In a separate study the recovery of Group A beta-hemolytic streptococci from 187 swabs was identical whether the swabs were streaked at 3 to 6 hours or at 18 to 24 hours.

Comparison of a latex agglutination test and four culture methods for identification of group A streptococci in a pediatric office laboratory.

A latex agglutination test and four culture methods for the detection of group A hemolytic streptococci were compared in a pediatric office laboratory. The anaerobic (GasPak) and Detekta-Kit methods produced the highest recovery rates, but aerobic incubation of 5% blood agar plates gave very acceptable results (sensitivity 92%, or 98% if the 1+ positive cultures were eliminated; specificity 100%), and had fewer disadvantages. Delaying inoculation of plates for 2 to 6 hours resulted in significantly greater numbers of strongly positive (3+ and 4+) cultures. The group A selective sheep blood agar media as used in this study offered no advantage. The Culturette test had a sensitivity of 72% and specificity of 98%, compared with the GasPak method, and 77% and 97%, respectively, compared with standard aerobic cultures. Thus it appears too insensitive to be used alone, but might complement culture methods in selected patients.

Critical weight loss and malnutrition in breast-fed infants.

In four infants of primiparous mothers, critical dehydration, hypothermia, and azotemia developed while they were being breast-fed exclusively. Three had significant hypernatremia, one had a perforated duodenal ulcer, and one had transient renal failure. Although the causes of the inadequate nutrition are unclear, these cases emphasize the necessity of close follow-up for breast-fed babies, especially those of primiparous mothers and those in whom there has been excessive weight loss while in the hospital.