Pediatric blood cultures.

The clinical and laboratory issues important in pediatric blood cultures are similar to those in adult blood cultures with a few noteworthy exceptions. The collection of an uncontaminated specimen and an ample volume of blood is more difficult, especially in neonates. In addition, children often have previously received oral antibiotics or a broad-spectrum parenteral antibiotic. The relative frequencies of the pathogens causing bacteremia in children are different in important ways from in adults. Haemophilus influenzae b, although much less common than in the past, is still an important pediatric pathogen. Meningococcemia is relatively more common in children than in adults, and enterobacteriaceae and anaerobes are relatively less common. Group B streptococci, E. coli, coagulase-negative staphylococci, and Candida sp. are the principal pathogens in neonates. More changes in the distribution of blood-borne pathogens can be expected in the future with the introduction of new or more effective vaccines against the pneumococcus, meningococcus, and, possibly, group B streptococcus. In suspected community-acquired bacteremia in otherwise normal children, a single aerobic blood culture of adequate volume is sufficient. Sick neonates, hospitalized children with indwelling intravascular devices, and immunocompromised children may need multiple blood cultures, paired cultures from an indwelling vascular catheter and a peripheral vein, or use of special media. There is no single optimal system for pediatric blood cultures. The BACTEC systems have been adopted as a single system in many hospitals serving both children and adults because of the favorable results reported in children and the preference of using a single automated system. To maximize the detection of bacteremia and fungemia, some laboratories may wish to combine a BACTEC system with a second complementary system, such as the Isolator. Anaerobic, mycobacterial, and other special blood culture media should be reserved for selected patients.

Immunogenicity and safety of Haemophilus influenzae type b-tetanus protein conjugate vaccine alone or mixed with diphtheria-tetanus-pertussis vaccine in infants.

Haemophilus capsular polysaccharide-tetanus toxoid conjugate (PRP-T) and diphtheria-tetanus-pertussis (DTP) vaccines were administered in a single syringe (group 1) or separate syringes (group 2) to 284 infants at 2, 4, and 6 months of age. Group 1 infants had a slightly greater incidence of local reactions. Systemic reactions were similar. The geometric mean titers of polyribosylribitol phosphate (PRP) serum antibody concentrations after the third dose of PRP-T vaccine were 4.8 and 4.3 micrograms/ml for groups 1 and 2, respectively. Antibody responses to DTP antigens were also similar. The immunogenicity and safety of the PRP-T and DTP vaccines are equivalent when the vaccines are administered in separate syringes or the same syringe to infants.

Use of intravenous gamma globulin to passively immunize high-risk children against respiratory syncytial virus: safety and pharmacokinetics. The RSVIG Study Group.

Infants with cardiopulmonary disease develop severe illness from respiratory syncytial virus (RSV) infection. Safety, feasibility, and pharmacokinetics of intravenous gamma globulin (IVIG) to prevent RSV illness were studied in 23 high-risk infants in a phase I trial. IVIG with an RSV neutralizing antibody titer of 1:1,100 in 5% solution was given monthly over a 2- to 4-h period in a clinical setting during the RSV season. The first group (n = 7) received 500 mg/kg of body weight, the second group (n = 9) received 600 mg/kg, and the third group (n =7) received 750 mg/kg. Serum was drawn prior to infusion and 2, 14, and 30 days after infusion. Total immunoglobulin G and RSV A2 and RSV B neutralizing antibody levels were obtained after the first IVIG infusion. Two children developed mild reversible pulmonary edema (group receiving 600 mg/kg per dose), and one developed hives and wheezing during one infusion (group receiving 500 mg/kg per dose). Twelve children developed subsequent RSV infection during two RSV seasons (November to April) over a 2-year follow-up period; 9 of 12 developed infection during the infusion year. Eleven illnesses were mild; one child died of progressive RSV illness (group receiving 500 mg/kg per dose). A cumulative infusion effect was not observed. IVIG appears safe and feasible in an outpatient setting, and at 750 mg/kg per dose, a target RSV antibody level of greater than or equal to 1:100 was achieved.

Immunization of high-risk infants younger than 18 months of age with split-product influenza vaccine.

Influenza is an important cause of serious illness in very young children with cardiopulmonary disease. A 4-year study was conducted at two centers to assess immunogenicity and safety of influenza split-product vaccine in children aged 3 to 18 months with bronchopulmonary dysplasia and congenital heart disease. A total of 113 children were studied: 62 children 3 to 5 months of age and 51 children 6 to 18 months of age. Sera were drawn prior to first and second immunization and 3 weeks after second immunization and were tested by hemagglutination inhibition; protection was defined as greater than 1:32. Ninety-five children were surveyed for adverse reactions. Seroresponses were age and antigen specific. Best responses for all ages were to A/Mississippi (H3N2) (97%). Children older than 6 months of age had better seroresponses to A/Leningrad (H3N2) (73%, P less than .03) and B/Victoria (62%, P less than .02) than did children younger than 6 months of age. Seroconversion rates to the remaining antigens were low. Only 9% of children experienced adverse reactions; all but one were mild. The immunologic mechanisms responsible for preventing serious influenzal disease and more effective immunization strategies need to be defined for very young high-risk children.

Early ribavirin treatment of respiratory syncytial viral infection in high-risk children.

A 3-year prospective, blinded, multicenter study was done to assess the efficacy of early ribavirin intervention in mild respiratory syncytial virus illness in children with bronchopulmonary dysplasia or with congenital heart disease. A cohort of 178 children younger than 36 months of age with bronchopulmonary dysplasia or congenital heart disease were followed. Forty-seven infants whose respiratory syncytial virus infection resulted in mild symptoms of less than or equal to 72 hours' duration received ribavirin (n = 20) or water placebo aerosol (n = 27) either in a hospital or at home. Outcome measures included respiratory and analog score, room air oxygen, saturation, and oxygen flow needed to maintain saturation at greater than or equal to 91%. No difference in age, gender, family size, passive smoking, baseline oxygen saturations in room air, or duration of symptoms before treatment was found between groups. After 3 days of therapy, ribavirin produced a greater rate of improvement of analog scores (p = less than or equal to 0.001), lower oxygen requirements (p = 0.01), and higher oxygen saturation (p = 0.01). Respiratory scores and total hospital days did not differ significantly between the groups. Treatment failure occurred in 2 of 20 children (10%) in the ribavirin group versus 5 of 27 children (18%) in the placebo group, a nonsignificant difference. No child required assisted ventilation or had an adverse reaction. We conclude that early ribavirin therapy may help to reduce morbidity from respiratory syncytial virus infection in high-risk young children.

Detection of respiratory syncytial virus antigen in nasal washings by Abbott TestPack enzyme immunoassay.

We compared the new Abbott TestPack (TP) respiratory syncytial virus (RSV) enzyme immunoassay (EIA) with cell culture and two commercial RSV EIAs (from Abbott Diagnostics and Kallestad Laboratories) by using split samples of fresh nasal washings from children with suspected RSV disease. Two tubes of HEp-2 cells were inoculated and observed for cytopathic effect for 14 days, and isolates were confirmed by immunofluorescence. The TP EIA was performed by following the manufacturer's instructions. Specimens positive by TP EIA but negative by culture were examined in a competitive inhibition (blocking) assay using the TP EIA, and rabbit anti-RSV serum. Of 218 specimens, 93 were positive by culture, 105 were positive by TP EIA, 80 were positive by the Abbott Diagnostics EIA, and 87 were positive by the Kallestad Laboratories EIA. The sensitivity, specificity, positive predictive value, and negative predictive value of the TP EIA were 92, 86, 81, and 93%, respectively. Of 20 apparently false-positive TP EIAs, 10 of 14 that were positive when retested were neutralized in the blocking assay, indicating that they were truly positive. The recalculated sensitivity, specificity, positive predictive value, and negative predictive value of the TP EIA were 92, 91, 90, and 93%, respectively. We conclude that the TP EIA is easy to perform, rapid (less than 0.5 h), and accurate.

Severe respiratory syncytial virus infection in older children.

Serious respiratory syncytial virus (RSV) disease requiring hospitalization occurs primarily in infants younger than 12 months. The incidence, risk factors, and clinical features in older children have not been studied extensively. Of 282 children hospitalized at our institution with severe RSV disease during a 3-year period, 62 (22%) were older than 12 months. These 62 older children were matched for sex, onset of illness, and hospital location with 62 hospitalized children younger than 12 months with proved RSV infection. Older children had underlying chronic disease more commonly than younger children (47 of 62 vs 24 of 62). Chronic illnesses in older children included bronchopulmonary dysplasia and/or reactive airway disease (34 of 47), congenital heart disease (9 of 47), gastrointestinal disease (7 of 47), and genetic disorders (7 of 47). Three of the four deaths from RSV infection occurred in older children; all four had underlying disease (three with congenital heart disease and one with biliary atresia). We conclude that children older than 12 months with underlying disease are at increased risk for serious or fatal RSV infection and are not always protected by previous RSV disease. Such older children should be considered candidates for passive or active immunoprophylaxis against RSV infection as such agents become available.

Comparative evaluation of radiometric tryptic soy broth versus radiometric tryptic soy broth with 10% sucrose for detection of bacteremia and fungemia in pediatric patients.

We compared BACTEC radiometric blood culture media with (8B) and without (6B) 10% sucrose for the detection of bacteremia and fungemia in pediatric patients at four university teaching hospitals that used identical methods for obtaining and processing specimens. Overall, the yields of microorganisms from 5,714 blood culture sets were no different in the two media, although a trend was noted favoring 6B for the detection of pneumococci. Speed of detection of positive results was faster in the 6B than in the 8B medium (P less than 0.05), largely due to the faster detection of Staphylococcus aureus in the 6B medium. We conclude that, overall, with pediatric patients the hypertonic 8B radiometric medium has no advantage and that it possibly has a modest disadvantage, compared with isotonic 6B radiometric medium.

Chlamydial pneumonia of infancy in siblings.

We describe two brothers born 16 months apart who were hospitalized with culture-proved chlamydial pneumonia of infancy due to the same immunotype of Chlamydia trachomatis. Presumably the mother had either been chronically infected or had been reinfected. Chlamydial pneumonia of infancy is a preventable disease if genital infection in pregnant women is diagnosed and treated. However, if pregnant women at high risk are not screened for C. trachomatis, multiple offspring may acquire the infection and develop serious perinatal chlamydial disease.

Respiratory syncytial virus infection in children with bronchopulmonary dysplasia.

Little is known about the risk of severe illness from respiratory syncytial virus infection in children with bronchopulmonary dysplasia. A prospective study was done of the natural history of respiratory syncytial virus infection in 30 children less than 2 years of age with bronchopulmonary dysplasia who were in a home oxygen program. Surveillance to identify children with acute respiratory symptoms was done by weekly telephone interview. Symptomatic children were examined, oxygen saturation was determined by oximetry, and nasopharyngeal lavage fluid was collected for virus cultures and rapid respiratory syncytial virus antigen tests. During the 4-month study period (December to April), 27 children had one or more acute respiratory illnesses, and respiratory syncytial virus developed in 16/27 (59%). Passive smoking and greater than or equal to four members in the home increased the risk of symptomatic respiratory syncytial virus (P less than .01 and P less than .03, respectively). Of 16 children, 11 (69%) required hospitalization. Of the 11 hospitalized children with respiratory syncytial virus, nine were either still receiving oxygen at home or required oxygen therapy within the previous 3 months v none of five nonhospitalized children (P less than .005). Five of the hospitalized children were greater than 12 months of age and five had respiratory syncytial virus infection previously that had been confirmed by culture results. Hospitalizations were prolonged and complicated. Seven of 11 children were hospitalized for greater than 1 week; four were admitted to the intensive care unit; four were treated with ribavirin aerosol, and two needed mechanical ventilation. There were no deaths.(ABSTRACT TRUNCATED AT 250 WORDS)

Detection of respiratory syncytial virus antigen in nasopharyngeal secretions by Abbott Diagnostics enzyme immunoassay.

We compared a rapid respiratory syncytial virus (RSV) antigen enzyme immunoassay (EIA) (Abbott Diagnostics, North Chicago, Ill.) with virus culture and with the indirect fluorescent-antibody test (FAT) by using nasopharyngeal washings from children with suspected RSV pneumonia or bronchiolitis. Fresh washings were used in all three tests. Specimens were inoculated into HEp-2 cells and human embryonic lung fibroblasts and observed for cytopathic effect. Cells in the centrifuged sediments of the nasal washes were examined for typical cytoplasmic fluorescence of RSV by FAT. The EIA cutoff was an optical density (OD) at 492 nm that was greater than the mean OD of the negative controls plus 0.1. An OD within +20% of the cutoff was considered borderline, and these specimens were retested. Of 289 specimens, 118 (41%) were positive by culture, 150 (52%) were positive by FAT, and 154 (53%) were positive by EIA. Eight borderline EIAs were all negative when the specimens were retested after storage at -70 degrees C. Of 17 specimens positive by EIA but negative by culture and FAT, 9 were blocked in a competitive EIA, indicating that they were true-positives and that the culture and FAT were falsely negative. The sensitivity, specificity, and predictive value (positive) of the EIA versus culture, FAT, or blocking assay were 90, 94, and 95%, respectively. We conclude that the Abbott RSV antigen EIA is highly sensitive and specific.

Controlled evaluation of blood culture medium containing gelatin and V-factor-analog for detection of septicemia in children.

Both Neisseria meningitidis and Haemophilus influenzae are important isolates recovered in blood cultures from septicemic children. Sodium polyanetholsulfonate is present in most blood culture media and can inhibit the growth of certain bacteria, including N. meningitidis. The addition of gelatin to blood culture media neutralizes this inhibition. The growth of H. influenzae is enhanced by specific growth factors such as hemin and NAD. The addition of gelatin and V-factor-analog (a proprietary supplement for enhancing the growth of H. influenzae) might have a positive effect on the yield and on the speed of detection of septicemia in children. To evaluate this possibility, we did 4,565 paired comparisons of blood cultured in BACTEC 6B (aerobic) medium with and without the addition of both 1.2% gelatin and V-factor-analog. More aerobic and facultative bacteria grew in the 6B than in the 6B-gelatin-V-factor-analog medium (P less than 0.01). Only seven isolates of Neisseria spp. were recovered during this study period, with the 6B medium performing as well as the supplemented medium. When microorganisms grew in both bottles, they did so at the same time except for H. influenzae and Candida albicans. H. influenzae was recovered earlier from the 6B-gelatin-V-factor-analog bottle (P less than 0.01), with a mean time to detection of 8.5 h compared with 15.9 h for the 6B bottle. C. albicans was recovered earlier from the 6B bottle (P less than 0.02), with a mean time to detection of 34.9 h compared with 71.6 h for the 6B-gelatin-V-factor-analog bottle. We conclude that the 6B medium in its present formulation is superior to bB supplemented with gelatin and V-factor-analog.

Severe facial injuries to infants due to unprovoked attacks by pet ferrets.

Three infants were attacked by pet ferrets and sustained severe facial injuries. Two of the children had their ears bitten off and required reconstructive surgery. The attacks were unprovoked. Two of the children were asleep in their cribs when they were bitten. Although ferrets are increasingly popular pets, we believe that they are not suitable pets for families with small children. Physicians should be aware that ferrets may unpredictably injure infants and that no effective rabies vaccine for ferrets is yet available.

Toxic effect of calcium alginate swabs on Neisseria gonorrhoeae.

Calcium alginate (CA)-tipped swabs have been reported to interfere with the recovery of herpes simplex virus, Chlamydia trachomatis, and Ureaplasma urealyticum and may cause cytotoxicity in cell culture. To determine whether CA swabs also inhibit the growth of Neisseria gonorrhoeae, we carried out a series of experiments using either CA swabs that were toxic or nontoxic in a cell culture cytotoxicity assay or nontoxic rayon or cotton swabs. Leaving a toxic CA swab in 3 ml of Mueller-Hinton broth inoculated with 10(4) CFU/ml caused rapid killing within 6 h at 37 degrees C; colony counts of five strains were less than 1% of those of Mueller-Hinton broth controls. When the tips of toxic CA swabs were inoculated directly and kept at 37 degrees C without holding medium, the swabs were sterile at 6 h. If the same swabs were placed in Amies medium with charcoal, organisms could still be recovered at 6 h. Toxicity was less at room temperature than at 37 degrees C. Inhibition of growth of N. gonorrhoeae was not seen with rayon or cotton swabs. The toxic component was neither the CA fiber nor the aluminum wire but probably the glue used to attach the fibers. We concluded that some lots of CA swabs kill N. gonorrhoeae in vitro. Survival of N. gonorrhoeae is improved with nontoxic swabs, particularly cotton swabs, and Amies medium with charcoal regardless of swab type.

Syringe preparation technique and minor adverse reactions to diphtheria-tetanus-pertussis immunization.

Minor local reactions and subcutaneous abscesses following diphtheria, tetanus and pertussis immunization have been attributed to vaccine left in the subcutaneous needle path from vaccine coating the needle. Various syringe preparation techniques have therefore been advocated to prevent reactions. To evaluate these recommendations we compared rates of minor reactions in 200 children randomly assigned to one of three groups that differed only in the handling of the filled syringe: in Group 1 the needle was changed before injection; in Group 2 the needle was wiped with sterile gauze before injection; in Group 3 the same needle was used to draw up and to inject the dose and was not wiped. Overall 27% of children had febrile (greater than 38 degrees C) reactions, 62% became fussy and 79% had a local reaction. Rates of reactions were nearly identical in the three groups, except that children in group 2 receiving their second dose or more of diphtheria-tetanus toxoid-pertussis vaccine were more likely to become febrile at greater than 38 degrees C (32%) or fussy (78%) (P less than 0.05 and P less than 0.02, respectively). We conclude that changing needles does not reduce the rate of minor local and systemic reactions. Wiping needles may increase the rate of reactions.

Comparison of nasopharyngeal washings and swab specimens for diagnosis of respiratory syncytial virus by EIA, FAT, and cell culture.

Respiratory secretions for viral diagnosis are often collected with nasopharyngeal (NP) swabs, although many laboratories recommend NP aspirates or washings. We compared results using NP washings and NP swabs in three diagnostic RSV tests, a rapid RSV EIA antigen test (Abbott Laboratories), an indirect fluorescent antibody test (FAT) with rabbit antiserum, and virus culture (HEp-2 cells). Paired samples were collected from 121 children with suspected RSV bronchiolitis or pneumonia. A minitip swap was passed into the nasopharynx for 10 sec, rotated and withdrawn. The opposite nares was irrigated with approximately 1 ml of saline and aspirated using a syringe and plastic feeding tube. Fifty-one children (42%) grew RSV in culture, 49 from NP washings versus 27 from NP swabs (p less than 0.001). Fifty-three (44%) were positive by FAT, 52 from NP washings versus 12 from NP swabs (p less than 0.001). Fifty-eight children (48%) had positive RSV EIA tests, 57 from NP washings versus 35 from NP swabs (p less than 0.001). Detection by EIA was more sensitive than culture regardless of the method of specimen collection. We conclude that NP washings are superior to NP swabs for RSV culture and rapid diagnosis by EIA or FAT.