Performance of a BACTEC nonradiometric medium for pediatric blood cultures.

A BACTEC aerobic nonradiometric medium, PEDS Plus, designed for diagnosis of pediatric bacteremia was evaluated in three hospital centers. Equivalent blood volumes (up to 5 ml) were inoculated into and incubated in BACTEC NR-6A (6A) and PEDS Plus broths. Among 4,581 compliant sets, 289 clinically significant organisms, representing more than 20 bacterial and two Candida species, were isolated. One hundred eighty-one isolates were recovered in both bottles, 75 in PEDS Plus only, and 33 in 6A only (P less than 0.001). Time to detection when both bottles were positive was the same for 129 isolates, detection with PEDS Plus was earlier for 39, and detection with 6A was earlier for 13 (P less than 0.005). Staphylococcus aureus was recovered significantly more often in PEDS Plus than in 6A (P less than 0.01), and more coagulase-negative staphylococci and pediatric pathogens (pneumococci, Haemophilus influenzae, and Streptococcus agalactiae) were recovered in PEDS Plus than in 6A. Coagulase-negative staphylococci and H. influenzae were detected significantly earlier in PEDS Plus (P less than 0.05 and less than 0.01, respectively). When the eight species of the family Enterobacteriaceae isolated were considered together, recovery in PEDS Plus was better than in 6A (P less than 0.05). For 66 of the 143 isolates from patients known to be on antimicrobial therapy at the time blood was drawn, PEDS Plus was superior to 6A. In 45 cases, organisms were isolated from PEDS Plus only (P less than 0.001) and in 21 cases they were isolated from PEDS Plus before 6A (P less than 0.01). PEDS Plus broth aids diagnosis of pediatric bacteremia by increasing recovery of etiologic agents and decreasing the time required for detection.

Haemophilus organisms: urinary tract pathogens in children?

The incidence and significance of isolation of Haemophilus species from urine specimens was determined at a pediatric referral center. The incidence was 0.27%, and half the isolates were pathogens. Evaluation of incidence and a cost analysis led to the conclusion that routine efforts to isolate Haemophilus from urine are not cost-effective.

Serotype and ampicillin susceptibility of Haemophilus influenzae causing systemic infections in children: 3 years of experience.

Over a 3-year period, 96% of systemic infections in children caused by Haemophilus influenzae were of serotype b. Of 346 invasive infections, 15 (4%) were caused by non-type b H. influenzae. The monthly prevalence of ampicillin resistance in all isolates was highly variable (0 to 63%). Ampicillin resistance in H. influenzae causing invasive disease occurred in 13% of non-type b and 21.8% of type b isolates. There was no significant difference (x2 - 0.21; p greater than 0.10) in the rate of ampicillin resistance between type b and non-type b H. influenzae causing systemic illness in children over a 3-year period.

In vitro susceptibility of 104 clinical isolates of Haemophilus influenzae to moxalactam (LY127935), ampicillin, chloramphenicol, and ticarcillin.

A total of 104 strains of Haemophilus influenzae isolated from pediatric patients over a 1-year period were tested for susceptibility to moxalactam (LY127935), ampicillin, chloramphenicol, and ticarcillin. Of these strains, 30 produced beta-lactamase. LY127935 inhibited 99% of the strains at a concentration of 0.125 microgram/ml; the remaining strain was inhibited by this antibiotic at 0.25 microgram/ml. beta-Lactamase-producing strains were inhibited by ampicillin at greater than or equal to 2 microgram/ml. beta-Lactamase-negative strains were all inhibited by ampicillin at less than or equal to 1 microgram/ml, except for one nontypable strain which required 2 microgram of ampicillin per ml for inhibition. All strains were susceptible to chloramphenicol at less than or equal to 4 microgram/ml. beta-Lactamase-producing strains were less susceptible (geometric mean = 4.702 microgram/ml) to ticarcillin than were strains which did not produce beta-lactamase (geometric mean = 0.331 microgram/ml). LY127935 susceptibility was not influenced by increasing inoculum size, as ws ampicillin susceptibility. Combinations of LY127935 and chloramphenicol or ampicillin were not antagonistic in vitro.

Modification of Tergitol-7 agar for differentiation of hydrogen sulfide-producing colonies.

The indication of H(2)S production by a modified Tergitol-7 agar combines the advantages of both selective and differential enteric media to provide a medium with broader coverage.