Phosphorylcholine on the lipopolysaccharide of Haemophilus influenzae contributes to persistence in the respiratory tract and sensitivity to serum killing mediated by C-reactive protein.

Haemophilus influenzae undergoes phase variation in expression of the phosphorylcholine (ChoP) epitope, a structure present on several invasive pathogens residing in the human respiratory tract. In this study, structural analysis comparing organisms with and without this epitope confirmed that variants differ in the presence of ChoP on the cell surface-exposed outer core of the lipopolysaccharide. During nasopharyngeal carriage in infant rats, there was a gradual selection for H. influenzae variants that express ChoP. In addition, genotypic analysis of the molecular switch that controls phase variation predicted that the ChoP+ phenotype was predominant in H. influenzae in human respiratory tract secretions. However, ChoP+ variants of nontypable H. influenzae were more sensitive to the bactericidal activity of human serum unrelated to the presence of naturally acquired antibody to ChoP. Serum bactericidal activity required the binding of C-reactive protein (CRP) with subsequent activation of complement through the classical pathway. Results of this study suggested that the ability of H. influenzae to vary expression of this unusual bacterial structure may correlate with its ability both to persist on the mucosal surface (ChoP+ phenotype) and to cause invasive infection by evading innate immunity mediated by CRP (ChoP- phenotype).

Mycobacterium avium intracellulare complex infection in HIV-infected children.

OBJECTIVE: To describe the incidence of, and risk factors for, Mycobacterium avium intracellulare complex (MAC) infection in HIV-infected children. SETTING: University-affiliated children's hospital. DESIGN AND METHODS: The medical records of 70 HIV-infected infants and children were reviewed retrospectively. RESULTS: Seven children (10% of the HIV-infected patients; 18% of those with AIDS) developed disseminated MAC (dMAC). An additional seven children had gastrointestinal colonization with MAC. Risk of dMAC was associated with increasing age, decreasing CD4 cell count, and (possibly) long-term steroid therapy. CONCLUSIONS: HIV-infected children are at risk of developing dMAC. Children older than 60 months and those with a CD4 cell count < 100 x 10(6)/l are most at risk.

Outpatient pediatric blood cultures: time to positivity.

OBJECTIVE: Using a continuously monitoring blood culture system, we determined the time to positivity of blood cultures performed on immunocompetent infants and children who were not receiving antibiotics at the time of culture. STUDY DESIGN: This study was conducted prospectively using blood cultures taken in the emergency department and outpatient clinics of an urban pediatric teaching hospital from February 1, 1993, through December 31, 1996. Cultures were excluded if obtained from patients receiving antibiotics, patients with a central line, patients with prosthetic devices, or those being followed by the oncology division. Our measures included: 1) recording the time to positive culture obtained by using a continuously monitoring blood culture instrument, 2) patient information derived from the hospital computer system concerning antibiotic use and the presence of indwelling central venous catheters and prosthetic devices, and 3) a chart review of 10% of patients from whom positive cultures were obtained. RESULTS: During the 47-month study period, 10 200 single bottle blood cultures were obtained, 711 (6.97%) of which became positive. Patients ranged in age from <1 week to 24 years (mean: 2.00 years). Two hundred fifty-eight cultures (36.3%) contained only pathogens, 370 (52%) contained only skin contaminants, and 83 (11.7%) contained a mixture of contaminant and pathogen. Of the 258 cultures containing only pathogens, 14% were positive by 12 hours, 87% by 24 hours, 92% by 36 hours, 95% by 48 hours, 98% by 60 hours, and 99.7% by 72 hours. Ninety-five percent of critical pediatric pathogens including Streptococcus pneumoniae, Salmonella and other Enterobacteriaceae, Neisseria meningitidis, and groups A and B streptococci were detected in <24 hours. CONCLUSION: Because 87% of all cultures containing pathogens were detected within the first 24 hours of incubation, this study can assist emergency department, clinic, and primary care clinicians when making critical decisions concerning patients on whom blood cultures were obtained. Data on time to positivity of blood cultures can be used in conjunction with clinical status to support clinicians in making patient management decisions. Use of short stay (

Evaluation of a rapid screening filter test for urinary tract infection in children.

OBJECTIVE: Clinical evaluation of a rapid screening filter test for urinary tract infection (UTI), FiltraCheck-UTI, comparison to the urine dipstick and conventional urinalysis for test performance and cost effectiveness in children. SETTING: Pediatric emergency department at an urban children's hospital. METHODS: Cross-sectional concordance study of 1298 children age 2 days to 19 years (50% < or = 2 years) for whom a urine culture was ordered; screening tests run by trained laboratory personnel; cost per case detected calculated; retrospective chart review for clinical information. RESULTS: Prevalence of UTI was 7.1%. Urine obtained from children < or = 2 years by catheter (97%) as part of an evaluation of fever or sepsis (82%). FiltraCheck-UTI was comparable with microscopy for bacteriuria (P = 0.11), sensitivity of 85% (95% confidence interval, 76 to 91) and specificity of 72% (95% confidence interval, 70 to 75%) but it was difficult detect Gram-positive organisms by this method (P < 0.001). Its performance varied by definition of UTI. The urine dipstick had the best specificity and was the most cost-effective rapid test. CONCLUSIONS: FiltraCheck-UTI is more expensive and has more false positives than the urine dipstick in detecting UTI in children. The dipstick continues to be the best inexpensive alternative to microscopy, but it is probably not an adequate screen for when to send a urine culture in young children.

Use of a rapid latex agglutination test to detect Salmonella and Shigella antigens from gram-negative enrichment broth.

The Wampole Bactigen Salmonella-Shigella is a latex agglutination test for rapid detection of Salmonella and Shigella from enteric enrichment broths. It is designed to identify those enrichment broths that require subculturing and eliminate further workup of negative broths. The authors compared the results of latex testing of gram-negative enrichment broths with culture results of the same broths. Primary culture plates were also inoculated with each specimen. A total of 2,481 rectal and stool specimens were used in the study. All specimens were inoculated onto a selection of primary culture media, and the specimen was placed into gram-negative broth. After incubation, the broths were tested with the latex and then subcultured to enteric agars. A total of 99 Salmonella and 29 Shigella were cultured from the specimens, with the latex test detecting 85 of 99 (85.5%) of the Salmonella and 26 of 29 (89.6%) of the Shigella. The overall specificity of the test was 96.4%, and the percentage agreement between latex and culture results was 95.9%.

Infections with Rhodococcus equi in children.

Three cases of serious infection in children, including the first two reports of bacteremia, due to Rhodococcus equi are described. Only seven pediatric cases have been reported to date. In the laboratory, R. equi can easily be misidentified as a nonpathogenic Corynebacterium spp. (diphtheroid) or a Mycobacterium spp. Despite an overall mortality rate of 25% in adults, no pediatric deaths have occurred due to R. equi. The organism is generally susceptible to vancomycin, aminoglycosides, chloramphenicol, and erythromycin, but, optimal duration of antibiotic therapy is unknown. Treatment with multiple antibiotics was successful in all three cases reported here. Although only a small number of cases have been reported in children, R. equi appears to be an important pediatric pathogen.

Laboratory diagnosis of fetal infections.

In utero infections of the fetus can lead to significant morbidity and mortality in the newborn child. The signs and symptoms of clinical disease, however, do not always suggest a given pathogen. The laboratory must be able to provide an early and accurate diagnosis of the causative agent so that prompt and appropriate antimicrobial therapy and medical care can be initiated. The scope of this article includes the methods employed by the laboratory to assist in the diagnosis of bacterial, fungal, parasitic, and viral infections of the fetus. Where appropriate, detection methods were addressed for the diagnosis of the major pathogens responsible for infection during the birth process.

Microbiology of the tonsils and adenoids in a pediatric population.

To investigate the microbial flora of the tonsils and adenoids, the core tissue from the tonsils and adenoids of 50 children undergoing tonsillectomy and adenoidectomy for either recurrent infection or airway obstruction was cultured aerobically and anaerobically, and the number of bacterial colonies was quantitated. The most common organisms isolated were alpha-hemolytic streptococci, nonpathogenic Neisseria species, Haemophilus species, Staphylococcus aureus, and Corynebacterium species. No anaerobes were identified. Bacterial isolates from the tonsils and adenoids were similar in number and frequency of occurrence. Potential pathogenic bacteria (Haemophilus species, S aureus, beta-hemolytic streptococci, and Streptococcus pneumoniae) were identified in 40 patients. Seventy-three percent of these patients shared a common pathogen in tonsil and adenoid tissue. Haemophilus species were recovered in 54% of patients and S aureus in 46%. No significant difference exists between the type and number of pathogens in patients undergoing adenotonsillectomy for recurrent infection or obstruction.

Bacterial translocation in mesenteric ischemia-reperfusion injury: is dysfunctional motility the link?

The authors previously reported that mesenteric ischemia and reperfusion (I/R) in a chronic newborn piglet model creates dysfunctional intestinal motility. Whether this leads to inadequate bacterial clearance and translocation (BT) through the gastrointestinal tract remains unclear. To test this hypothesis the authors used their chronic piglet model (weight, 3.5 +/- 0.3 kg; age, 18 +/- 4 days; on formula feeding); nonocclusive mesenteric ischemia was induced via reversible pericardial tamponade. Mesenteric flow (SMA Doppler measurement via the retroperitoneal approach) was decreased to 25% +/- 5% of baseline for 300 minutes in the ischemia group (n = 7) and followed by 14 hours of reperfusion in the I/R group (n = 6). Control subjects had a sham operation (n = 7). Mesenteric lymph nodes (MLN), liver (L), spleen (S), ileum, peritoneum, and blood were harvested for blind quantitative microbial analysis. Subjects in the control group had no cultures positive for growth. Eighty-five percent of animals in the ischemia group had positive MLN cultures only (P < .05 v control). All piglets in the I/R group had positive MLN cultures (P < .05 v control), and one third of them manifested bacteremia. Histological examination did not show mucosal disruption in any group. The validity of this model is confirmed by the negative cultures in the control group and by the presence of normal ileal flora in all animals. In the ischemia and I/R groups, MLN cultures were consistently positive with gram-negative bacilli (Escherichia coli and/or Klebsiella pneumoniae). When subjects of the I/R group had more than 1,000 colonies in the MLN, bacteremia with the translocating organisms was also identified.(ABSTRACT TRUNCATED AT 250 WORDS)

Octreotide does not prevent bacterial translocation in an infant piglet model of intestinal ischemia-reperfusion.

The process of bacterial translocation (BT) after ischemia/reperfusion (I/R) injury is reported to be mediated by local mucosal factors, the effects of pancreatic enzymes, epithelial disruption, and by dysfunctional intestinal motility. Octreotide (OCT), a somatostatin analog, has been postulated to protect against BT by influencing one or more of these factors. Twenty-two formula-fed piglets (weight, 3.5 +/- 0.5 kg; age, 20 +/- 5 days) were divided into four groups: control (no drug given; no I/R; n = 6), I/R (no drug given; n = 5), I/R plus low-dose OCT (LD OCT, 0.08 microgram/kg; n = 6), and I/R plus high-dose OCT (HD OCT, 8 micrograms/kg; n = 5). All experimental subjects had nonocclusive mesenteric ischemia induced by reversible pericardial tamponade with mesenteric flow decreased to 25 +/- 5% of baseline for 5 hours followed by 15 +/- 5 hours of reperfusion. Mesenteric lymph nodes (MLN), liver, spleen, blood, and peritoneum were harvested for blind microbial analysis. None of the animals in the control group experienced translocation to the tissues tested. All of the animals in the I/R group experienced BT to the MLN. The subjects in the LD OCT and HD OCT groups experienced BT to the MLN 66% and 80% of the time, respectively. Despite the reported clinical evidence that OCT can protect the intestinal mucosa from injury and increase the clearance of bacteria from the gastrointestinal tract, in this study in which variables other than I/R known to promote bacterial translocation were eliminated, OCT failed to modify or prevent the occurrence of translocation to the MLN after I/R injury.

The management of prepubertal children with gonorrhea.

To determine whether test-of-cure cultures are necessary for prepubertal children diagnosed with Neisseria gonorrhoeae, we examined the records of all 66 patients < 10 years old seen at Children's Hospital of Philadelphia over a 7.5-year period (1987-1994) diagnosed with gonorrhea. Ninety-eight percent had genital discharge on examination. All children with genital gonorrhea were symptomatic, but only 10% of children with rectal gonorrhea and 20% with pharyngeal infection were symptomatic. Seventy-seven percent of children were treated with ceftriaxone. Of these, 72% returned for test-of-cure cultures. Ninety-three percent of children had complete resolution of physical symptoms at test-of-cure, and all follow-up cultures were negative for N. gonorrhoeae. Our data suggest that most prepubertal children with gonorrhea are symptomatic at initial presentation and are cured after recommended treatment with ceftriaxone. The Centers for Disease Control and Prevention recommendations for obtaining test-of-cure cultures in young children with gonorrhea are unnecessary, potentially harmful, and should be revised.

Antifungal susceptibility against yeasts isolated from pediatric oncology patients.

Yeast infections cause morbidity in children with cancer and we evaluated species distribution and antifungal susceptibilities of the etiologic agents in this group. Specimens from 58 children yielded 64 cultures positive for yeasts. Central venous catheters were present in 56 (97%) of the children and neutrophil counts were <500 cells/ml3 in 34% of the patients. Twenty-two (38%) had received recent antifungal treatment, with 15 (25%) receiving fluconazole (FLU) prophylaxis. The Candida isolates recovered from four (27%) of the children on FLU prophylaxis, were resistant to this drug. Candida albicans isolates were susceptible to 100% of antifungals tested, whereas non-C. albicans Candida spp. were variable in their susceptibility patterns. FLU prophylaxis minimally affected susceptibility.

Preparation and use of cytoplasmic antigens for the serodiagnosis of paracoccidioidomycosis.

A cytoplasmic antigen of Paracoccidioides brasiliensis (strain MTC) prepared from the yeast phase grown in the chemically defined medium of McVeigh and Morton is described. This antigen can be easily prepared, does not vary from lot to lot, and can be lyophilized without loss of activity or potency. In the immunodiffusion test, the cytoplasmic antigen demonstrated a sensitivity of 97% and a specificity of 100% when tested against 218 sera from 139 cases of paracoccidioidomycosis. When 177 sera from patients with fungal diseases other than paracoccidioidomycosis were tested by immunodiffusion, there were no false-positive reactions. In an enzyme-linked immunosorbent assay, the antigen was equally effective in identifying cases, giving a sensitivity of 100% and a specificity of 99% when a 1:640 titer was considered the threshold for clinical significance. Antigenic components in the cytoplasmic extract of P. brasiliensis were examined after fractionation by concanavalin A-Sepharose 4B column chromatography. The fraction of the cytoplasmic antigen that binds to the concanavalin A column is material identical to the specific b1 (antigen 1) precipitin band described by A. Restrepo and L. H. Moncada (Appl. Microbiol. 28:138-144, 1974).

Growth characteristics of the yeast phase of Paracoccidioides brasiliensis in a chemically defined medium.

The growth of four clinical strains of Paracoccidioides brasiliensis was investigated using the chemically defined medium of McVeigh and Morton. Emphasis was placed upon controlling conditions of inoculum preparation, age of inoculum used, and the homogeneity of samples used for analysis. The medium was evaluated for its ability to support growth of the yeast phase of P. brasiliensis at 37 degrees C. Cultures were followed for 240 h and growth patterns were determined by measuring optical density, dry weight, nucleic acids and protein. The medium is excellent for growing the yeast phase of P. brasiliensis. The exponential phase lasted an average of 135 h and the stationary phase 72 h; a decline began after 207 h. This defined medium supports abundant growth of the yeast phase of P. brasiliensis and may thus prove useful in the preparation of yeast-phase antigens.

Identification of clinical yeast isolates by using the Microring YT.

The Microring YT (MYT; Medical Wire & Equipment Co., Victory Gardens, N.J.) is a system for the rapid (24 to 48 h) identification of yeasts. The MYT system was evaluated and compared with the API20C (Analytab Products, Plainview, N.Y.) system for its ability to identify 677 clinical yeast isolates. Only 458 isolates (68%) were correctly identified by the MYT system, and the accuracy of the system varied considerably (0 to 96%), depending on the species. While MYT was less expensive and convenient to use and results were available 24 h sooner, it is inadequate for identification of many commonly isolated yeasts and is not designed for the identification of Cryptococcus species.