Antibiotic sensitivity and resistance patterns in pediatric staphylococcal scalded skin syndrome.

Historical resistance patterns often guide empiric antibiotic choices in staphylococcal scalded skin syndrome (SSSS), but little is known about the difference in susceptibility between SSSS and other childhood staphylococcal infections. A retrospective chart review of culture-confirmed cases of SSSS seen in the inpatient dermatology consultation service at the Children's Hospital of Philadelphia between 2005 and 2011 was performed. Most cases of SSSS at our institution are due to oxacillin-susceptible Staphylococcus aureus, and approximately half of the cases are due to clindamycin-resistant strains. Clindamycin and a penicillinase-resistant penicillin are suggested as empiric treatment for SSSS until culture susceptibility data are available to guide therapy.

Emergency department epidemiology of pneumococcal bacteremia in children since the institution of widespread PCV7 vaccination.

BACKGROUND: The heptavalent pneumococcal conjugate vaccine (PCV7) has produced a shift in the epidemiology of invasive infections from Streptoccoccus pneumoniae. OBJECTIVE: Our aim was to determine the temporal changes in pneumococcal bacteremia (Streptococcus pneumoniae bacteremia [SPB]) in the emergency department (ED) since the introduction of PCV7. METHODS: This was a retrospective cohort study of children 0-18 years with SPB evaluated from 1998-2009 in a tertiary-care pediatric ED. The primary outcome was annual proportion of children with SPB from PCV7 serotypes (ie, 4, 6B, 9V, 14, 18C, 19F, and 23F) and nonvaccine serotypes (NVT). Rates of SPB (per 10,000 ED visits) were calculated. SPB was analyzed by time period: before October 2000 was considered "pre-PCV7," November 2000 to October 2003 was considered "peri-PCV7," and after November 2003 was "post-PCV7." Febrile young children (FYC) were defined as children age <36 months and fever without source. RESULTS: A total of 201 episodes of SPB occurred during the study, with a median age of 20.3 months (interquartile range 10.7-49.5 months; range 1.6-215.4 months); 56.7% were male and 69.7% were African American. SPB from PCV7 serotypes decreased more than fourfold, from 82.2% pre-PCV7 to 19.5% peri- and post-PCV7. Most SPB was from NVT serotype 19A (31.3%) peri- and post-PCV7. Annual rates of SPB were 4.01/10,000 ED visits pre-PCV7, decreasing to 2.10 peri-PCV7, and 1.75 post-PCV7. Among the 56 (27.8%) FYC with SPB, NVT were responsible for 11.5% of SPB pre-PCV7, and increased to 80.0% peri- and post-PCV7 (p < 0.001). CONCLUSIONS: Rates of SPB have decreased since the introduction of PCV7, yet SPB still occurs among children in the ED. NVT are increasing in prevalence, and SPB from PCV7-serotypes have decreased.

Declining incidence of candidemia in a tertiary inpatient pediatric population.

We examined the incidence of candidemia, Candida species distribution, and antifungal susceptibility patterns in a pediatric institution. We identified 301 episodes of candidemia from 2001 to 2010 inclusive. Annual incidence decreased from 0.68 to 0.12 cases/1,000 patient days between 2004 and 2010. Candida albicans was the most common species, followed by C. parapsilosis. All isolates tested were susceptible to amphotericin B and caspofungin, but 11% were resistant or dose-dependently susceptible to fluconazole.

Clostridium difficile testing algorithms using glutamate dehydrogenase antigen and C. difficile toxin enzyme immunoassays with C. difficile nucleic acid amplification testing increase diagnostic yield in a tertiary pediatric population.

We evaluated the performance of the rapid C. diff Quik Chek Complete's glutamate dehydrogenase antigen (GDH) and toxin A/B (CDT) tests in two algorithmic approaches for a tertiary pediatric population: algorithm 1 entailed initial testing with GDH/CDT followed by loop-mediated isothermal amplification (LAMP), and algorithm 2 entailed GDH/CDT followed by cytotoxicity neutralization assay (CCNA) for adjudication of discrepant GDH-positive/CDT-negative results. A true positive (TP) was defined as positivity by CCNA or positivity by LAMP plus another test (GDH, CDT, or the Premier C. difficile toxin A and B enzyme immunoassay [P-EIA]). A total of 141 specimens from 141 patients yielded 27 TPs and 19% prevalence. Sensitivity, specificity, positive predictive value, and negative predictive value were 56%, 100%, 100%, and 90% for P-EIA and 81%, 100%, 100%, and 96% for both algorithm 1 and algorithm 2. In summary, GDH-based algorithms detected C. difficile infections with superior sensitivity compared to P-EIA. The algorithms allowed immediate reporting of half of all TPs, but LAMP or CCNA was required to confirm the presence or absence of toxigenic C. difficile in GDH-positive/CDT-negative specimens.

Comparison of the Idaho Technology FilmArray system to real-time PCR for detection of respiratory pathogens in children.

The FilmArray Respiratory Panel (RP) multiplexed nucleic acid amplification test (Idaho Technology, Inc., Salt Lake City, UT) was compared to laboratory-developed real-time PCR assays for the detection of various respiratory viruses and certain bacterial pathogens. A total of 215 frozen archived pediatric respiratory specimens previously characterized as either negative or positive for one or more pathogens by real-time PCR were examined using the FilmArray RP system. Overall agreement between the FilmArray RP and corresponding real-time PCR assays for shared analytes was 98.6% (kappa = 0.92 [95% confidence interval (CI), 0.89 to 0.94]). The combined positive percent agreement was 89.4% (95% CI, 85.4 to 92.6); the negative percent agreement was 99.6% (95% CI, 99.2 to 99.8). The mean real-time PCR threshold cycle (C(T)) value for specimens with discordant results was 36.46 ± 4.54. Detection of coinfections and correct identification of influenza A virus subtypes were comparable to those of real-time PCR when using the FilmArray RP. The greatest comparative difference in sensitivity was observed for adenovirus; only 11 of 24 (45.8%; 95% CI, 27.9 to 64.9) clinical specimens positive for adenovirus by real-time PCR were also positive by the FilmArray RP. In addition, upon testing 20 characterized adenovirus serotypes prepared at high and low viral loads, the FilmArray RP did not detect serotypes 6 and 41 at either level and failed to detect serotypes 2, 20, 35, and 37 when viral loads were low. The FilmArray RP system is rapid and extremely user-friendly, with results available in just over 1 h with almost no labor involved. Its low throughput is a significant drawback for laboratories receiving large numbers of specimens, as only a single sample can be processed at a time with one instrument.

Cerebrospinal fluid reference ranges in term and preterm infants in the neonatal intensive care unit.

OBJECTIVE: To determine reference ranges of cerebrospinal fluid (CSF) laboratory findings in term and preterm infants in the neonatal intensive care unit. STUDY DESIGN: Data were collected prospectively as part of a multisite study of infants aged <6 months undergoing lumbar puncture for evaluation of suspected sepsis. Infants with a red blood cell count >500 cells/µL or a known cause of CSF pleocytosis were excluded from the analysis. RESULTS: A total of 318 infants met the inclusion criteria. Of these, 148 infants (47%) were preterm, and 229 (72%) received antibiotics before undergoing lumbar puncture. The upper reference limit of the CSF white blood cell (WBC) count was 12 cells/µL in preterm infants and 14 cells/µL in term infants. CSF protein levels were significantly higher in preterm infants (upper reference limit, 209 mg/dL vs 159 mg/dL in term infants; P < .001), and declined with advancing postnatal age in both groups (preterm, P = .008; term, P < .001). CSF glucose levels did not differ in term and preterm infants. Antibiotic exposure did not significantly affect CSF WBC, protein, or glucose values. CONCLUSIONS: CSF WBC counts are not significantly different in preterm and term infants. CSF protein levels are higher and decline more slowly with postnatal age in preterm infants compared with term infants. This study provides CSF reference ranges for hospitalized preterm and term infants, particularly in the first month of life.

Mycobacterium chelonae-abscessus complex associated with sinopulmonary disease, Northeastern USA.

Members of the Mycobacterium chelonae-abscessus complex represent Mycobacterium species that cause invasive infections in immunocompetent and immunocompromised hosts. We report the detection of a new pathogen that had been misidentified as M. chelonae with an atypical antimicrobial drug susceptibility profile. The discovery prompted a multicenter investigation of 26 patients. Almost all patients were from the northeastern United States, and most had underlying sinus or pulmonary disease. Infected patients had clinical features similar to those with M. abscessus infections. Taxonomically, the new pathogen shared molecular identity with members of the M. chelonae-abscessus complex. Multilocus DNA target sequencing, DNA-DNA hybridization, and deep multilocus sequencing (43 full-length genes) support a new taxon for these microorganisms. Because most isolates originated in Pennsylvania, we propose the name M. franklinii sp. nov. This investigation underscores the need for accurate identification of Mycobacterium spp. to detect new pathogens implicated in human disease.

Ulceroglandular tularemia.

A 14-year-old boy presented with fevers and nonspecific flu-like symptoms, as well as an enlarging ulcerated plaque involving the upper back, lymphadenopathy, and bilateral pulmonary nodules. Bacterial cultures of ulcer tissue grew Francisella tularensis on enriched chocolate agar plates. Making the diagnosis requires a high index of suspicion, and communication with the laboratory to successfully and safely culture these highly pathogenic bacteria is imperative.

A writing group for female assistant professors.

INTRODUCTION: The number of female medical school faculty being promoted and the speed at which they are promoted have not kept pace with their male counterparts at many institutions. One of the reasons is that these women are not publishing peer reviewed manuscripts at an equivalent rate. This study evaluates the impact of a women's writing group on faculty publication rates. MATERIALS AND METHODS: The writing group was conducted by 2 senior faculty members at the University of Pennsylvania School of Medicine and targeted female junior faculty. The writing group consisted of a didactic skills curriculum, question sessions, and both faculty and peer support to improve publishing rates. Curriculum vitae were collected, and PubMed and Ovid searches were used to establish the publishing productivity of the writing group participants both before and after participation in the writing group. RESULTS: On average, women who completed the writing group showed a nearly 3-fold increase in average publishing rate from 1.5 papers per year preceding the course to 4.5 per year following completion of the writing group (p<.001). CONCLUSIONS: The results from our program suggest that a women's writing group is an effective intervention for increasing publishing rates of female junior faculty. In addition to the documented improvement in publication rates, we watched participants develop clearer writing styles, lose many of their inhibitions about writing, respond to group affiliation and collaboration, and gain tremendous self-confidence.

The brief CV review session: one component of a mosaic of mentorship for women in academic medicine.

BACKGROUND: In the current climate of increasing demands on a disproportionately small number of senior female faculty, we implemented a brief curriculum vitae (CV) review session as an opportunity to expand the professional network of junior women faculty and provide them with additional formal career advice. METHODS: For 3 years, junior (mentees) and senior (mentors) faculty from different departments were paired in half-hour CV review sessions, as part of an annual conference focused on professional development for faculty women. Participating faculty received questionnaires to assess their experience with the sessions, and their feedback was combined over all 3 years and compared using chi2 and Fisher's tests. RESULTS: During the 3 years, there were 93 CV review sessions. Although 84% of the mentees reported having a mentor, only 62% of mentees reported that any previous mentoring experience was helpful. Most (90%) participated in the CV review to determine if their career was "on track." The mentees reported that the CV review session was helpful (93%), provided new information (87%), and identified that they were "on track" for promotion (75%). The mentors felt that their mentees were progressing appropriately in their career (78%) and provided specific recommendations for the mentees (100%). The majority (78%) of mentors felt comfortable mentoring junior faculty outside their department. CONCLUSIONS: Brief interventions, such as a CV review session, can provide additional counsel to junior faculty, helping them assess their career progress as part of a mosaic of mentorship.

Polymicrobial bloodstream infections among children and adolescents with central venous catheters evaluated in ambulatory care.

BACKGROUND: Bloodstream infections (BSIs) are an ever-present concern for clinicians evaluating ill-appearing pediatric patients with central venous catheters (CVCs) in the ambulatory care setting. METHODS: We performed a case-control study of a cohort of 200 pediatric patients who were evaluated in the ambulatory care setting and who were found to have laboratory-confirmed BSI in the context of a CVC. This study sought to compare patients with polymicrobial versus monomicrobial BSIs to identify potential risk factors for polymicrobial BSI. RESULTS: Of the 200 patients enrolled in the study, 73 (37%) had a polymicrobial BSI. Patients with polymicrobial BSI were more likely than those with monomicrobial BSI to be younger (P=.002) and less likely to have been recently discharged from the hospital (P=.01). The odds of a polymicrobial BSI were >4 times greater for patients aged <3 years than for those aged >or=3 years (odds ratio, 4.54; 95% confidence interval, 1.68-12.29), and the odds were 50% lower for those discharged from the hospital in the prior 7 days than for those without recent hospitalization (odds ratio, 0.46; 95% confidence interval, 0.22-0.95) after controlling for an underlying cancer diagnosis and the time of year during which a patient presented. Recent antibiotic use, recent BSI, duration that the CVC had been in place, and underlying gastrointestinal dysfunction were not associated with a risk of polymicrobial BSI. CONCLUSIONS: Younger children and those who had not recently been discharged from the hospital had an increased risk of developing catheter-related polymicrobial BSI. Special consideration should be given to the increased likelihood of polymicrobial BSIs in these pediatric patients when initiating empirical antimicrobial therapy.

Isolation and characterization of a novel Francisella sp. from human cerebrospinal fluid and blood.

We describe the isolation of a Francisella sp. from normally sterile sites in acutely ill patients in two different states within 2 years. Microbiologic and molecular analyses indicate that this organism represents a novel Francisella sp. Clinicians and microbiologists should be aware of this new potential pathogen, as infection may be more common than recognized.

Invasive pneumococcal disease among human immunodeficiency virus-infected children, 1989-2006.

OBJECTIVE: The heptavalent pneumococcal conjugate vaccine (PCV7) has decreased the incidence of pediatric invasive pneumococcal disease (IPD) in the United States. Few data exist on the changing IPD incidence in HIV-infected children. METHODS: Diagnostic codes and clinical microbiology laboratory records identified cases of IPD from 1989 to 2006 in perinatally-infected children <18 years of age followed at an urban HIV clinic. IPD incidence was calculated and serotype distribution and antibiotic resistance were recorded. RESULTS: Two-hundred fifty-six patients were followed for 1756 person-years (PY). The sample was 59% female, 76% black, 14% white, and 8% Hispanic. Of 21 episodes of IPD (1200/100,000 PY), 17 (81%) were female. IPD cases had a median age of 6.3 years (interquartile range [IQR]: 2.3-9.9 years), median CD4% of 17% (IQR: 11-28%), and median CD4 count of 415 cells/mm (range, 2-1699 cells/mm). Bacteremia was the commonest form of IPD (19 episodes; 1080/100,000 PY). After HAART introduction in 1996, the incidence of IPD decreased 84% from 1862/100,000 PY in 1989-1995 to 292/100,000 PY in 1997-1999 (incidence rate ratio [IRR]: 0.16, P = 0.03). After PCV7 introduction in 2000, IPD incidence showed a nonsignificant increase from 292 of 100,000 PY in 1997-1999 to 860 of 100,000 PY in 2001-2006 (IRR: 2.94; P = 0.16). The percentages of IPD isolates nonsusceptible to penicillin and trimethoprim-sulfamethoxazole were 19% and 33%, respectively. Vaccine serotypes accounted for 38% of isolates, vaccine-related 14%, nonvaccine 33%, and the serotype was unknown in 14%. CONCLUSIONS: The incidence of IPD among perinatally HIV-infected children decreased after the introduction of HAART. Ongoing monitoring is required to determine the effect of PCV7 on IPD in this vulnerable population.

Bloodstream infection caused by Stenotrophomonas maltophilia in children.

BACKGROUND: Stenotrophomonas maltophilia, a multidrug resistant Gram-negative pathogen, has become a more frequent cause of bloodstream infections (BSI). Little is known about development of S. maltophilia bacteremia in children. The objective of this study was to define risk factors and outcomes associated with S. maltophilia BSI in children. METHODS: This was a retrospective case-control study conducted at The Children's Hospital of Philadelphia between January 1, 2000 and July 31, 2005. All patients with S. maltophilia BSI were compared with a random sample of patients with non-Stenotrophomonas Gram-negative rod BSI. RESULTS: Fifty-one cases and 103 control subjects were included in the study. The median patient age was 2 years (interquartile range: 1 day-8.5 years). Patients with S. maltophilia BSI were significantly more likely to have a malignancy and be coinfected with other organisms than those with other Gram-negative rod infections. On multivariate analysis, patients with S. maltophilia BSI were more likely to develop their infection in the home setting (adjusted OR, 4.18; 95% CI: 1.44-12.16; P = 0.009). Additionally, prior exposure to trimethoprim-sulfamethoxazole, receipt of steroids or other immunosuppressive medication in the 30 days preceding infection and black race were associated with the development of S. maltophilia BSI. CONCLUSIONS: Patients with Stenotrophomonas maltophilia BSI are more likely to have a polymicrobial infection and develop their infection in the home setting compared with patients with BSI caused by other Gram-negative rods.

Emergence of vaccine-related pneumococcal serotypes as a cause of bacteremia.

BACKGROUND: The heptavalent pneumococcal conjugate vaccine (PCV7) has decreased the incidence of invasive pneumococcal disease among children in the United States. In the postlicensure period, the impact of non-PCV7 serotypes against pediatric pneumococcal bacteremia is unknown. METHODS: Episodes of bacteremia due to Streptococcus pneumoniae and other respiratory pathogens (ORP), namely Neisseria meningitidis, Haemophilus influenzae, and Moraxella catarrhalis, were identified in children <18 years old at the Children's Hospital of Philadelphia from January 1999 to May 2005. For pneumococci, serotype distribution and antibiotic resistance were compared. RESULTS: A total of 188 episodes of pneumococcal bacteremia and 55 episodes of ORP bacteremia were identified. By comparing data from 1999-2000 with data from 2001 to May 2005, we found that the incidence of pneumococcal bacteremia decreased by 57%. The incidence of bacteremia caused by ORPs was unchanged; 1.43 episodes (95% confidence interval [CI], 0.84-2.29 episodes) to 1.25 (95% CI, 0.88-1.71) per 10,000 emergency department visits. Vaccine serotypes caused 85% of episodes of bacteremia in 1999-2000, compared with 34% of episodes of bacteremia in 2001 to May 2005 (P<.01). The percentage of isolates nonsusceptible to penicillin increased from 25% to 39% (P<.05). The percentage of episodes of pneumococcal bacteremia caused by vaccine-related serotypes--those of the same serogroup but not of the same serotype as PCV7--increased from 6% of episodes in the prelicensure period to 35% of episodes in the postlicensure period (P<.01). Rates of serotype pneumococcal bacteremia caused by nonvaccine serotypes were not statistically different between the 2 periods. CONCLUSIONS: The overall incidence of pneumococcal bacteremia decreased by 57% after the introduction of PCV7. During the postlicensure period, there were significant decreases in the incidence of pneumococcal bacteremia caused by vaccine serotypes; however, rates of penicillin resistance and bacteremia due to vaccine-related serotypes increased.

Clinical and molecular epidemiology of community-acquired methicillin-resistant Staphylococcus aureus infections among children with risk factors for health care-associated infection: 2001-2003.

BACKGROUND: Methicillin-resistant Staphylococcus aureus (MRSA) has recently emerged as a common cause of infection in children in many parts of the world. The epidemiology of community-acquired MRSA (CA-MRSA) among healthy children has been recently described. However, little is known about CA-MRSA in children with underlying medical conditions. OBJECTIVE: To compare the clinical and molecular epidemiology of CA-MRSA in children with and without risk factors for health care-associated infections (RF-HAI). METHODS: We conducted a 3-year retrospective cohort study of children with CA-MRSA infection. RF-HAI, including hospitalization within the past year, indwelling medical devices or chronic medical condition, were identified by chart review. Genetic relatedness of CA-MRSA strains was assessed by pulsed field gel electrophoresis. Polymerase chain reaction was used to detect Panton-Valentine leukocidin and determine staphylococcal chromosomal cassette carrying the mecA methicillin-resistant gene (SCCmec) type. RESULTS: We identified 446 episodes of community-acquired S. aureus infections, of which 134 (30%) were caused by MRSA. During the 3-year study period, the proportion of S. aureus infections caused by MRSA rose from 15% (12 of 80) to 40% (93 of 235) (P < 0.001) with the increase noted predominately in children with skin and soft tissue infections. RF-HAI were identified in 56 (42%) patients with CA-MRSA. Among subjects with CA-MRSA, children with RF-HAI were more likely to have had an invasive infection than healthy children (32% versus 5%; P < 0.001). CA-MRSA isolates from children with RF-HAI were similar to those without RF-HAI; all laboratory-retained CA-MRSA isolates harbored the SCCmec type IV cassette, and almost all isolates were susceptible to trimethoprim-sulfamethoxazole and clindamycin. However, pulsed field gel electrophoresis revealed greater molecular diversity among CA-MRSA isolates recovered from children with RF-HAI compared with those from otherwise healthy children (P = 0.001). Additionally CA-MRSA isolates from children with RF-HAI were less likely to contain sequences for Panton-Valentine leukocidin (P < 0.001) and more likely to be resistant to 3 or more classes of antibiotics (P = 0.033). CONCLUSION: CA-MRSA strains recovered from children with RF-HAI were phenotypically similar to those recovered from healthy children The absence of SCCmec type II or III MRSA among children with RF-HAI suggests that CA-MRSA strains might have become endemic within pediatric health care facilities.

Antifungal susceptibility of Candida spp. isolated from pediatric patients: a survey of 4 children's hospitals.

Candida species are the most common cause of fungal infections in hospitalized patients. Recent studies have reported a relative reduction in the rates of infection caused by Candida albicans and a shift toward non-albicans Candida spp. Data on the distribution and susceptibility of Candida spp. from children's hospitals are limited. Clinical isolates of Candida were collected from 4 US children's hospitals in 2003. Broth dilution MICs for amphotericin B, fluconazole, voriconazole, caspofungin, posaconazole, and ravuconazole were performed according to National Committee for Clinical Laboratory Standards-approved methodology. A total of 179 clinical isolates were identified and included. Of 179, 77 (43%) were C. albicans. Candida parapsilosis isolates were the second most frequently identified (57/175, 32%), followed by Candida glabrata, Candida tropicalis, and Candida lusitaniae (approximately 8% each). Caspofungin was the most active agent in vitro against all Candida spp. Fluconazole resistance was seen among C. glabrata, C. tropicalis, and Candida krusei isolates. Newer azoles had improved activity against fluconazole-resistant isolates of Candida. Among isolates of C. parapsilosis, nearly 20% were resistant to amphotericin B. The current study highlights the emergence of C. parapsilosis as a distinct pediatric pathogen with clinical and therapeutic implications. Furthermore, our current susceptibility data include newer antifungal agents that appear to be quite active in vitro and may provide new therapeutic options for the treatment of serious yeast infections in children.

An outbreak of Serratia marcescens bacteremia after general anesthesia.

OBJECTIVE: To investigate an outbreak of Serratia marcescens bacteremia among patients after general anesthesia. DESIGN: A case-control study. SETTING: A 304-bed, pediatric teaching hospital. PATIENTS: Twenty-three pediatric patients who developed S. marcescens bacteremia within 2 weeks after general anesthesia between June 15 and September 22, 1999, were compared with 46 age-matched control-patients who had undergone procedures on the same clinical services of the hospital during the same period. RESULTS: Cases were distributed over a wide range of surgical services and were not correlated with exposure to any of the surgical, anesthesia, or nursing staff. Case-patients were significantly more likely than control-patients to have received cefazolin (odds ratio [OR], 11.1; 90% confidence interval [CI90], 1.9 to 24.3) or to have had perioperative placement of a central vascular catheter (OR, 4.2; CI90, 1.2 to 18.8). The timing of the procedures of patients who subsequently developed S. marcescens bacteremia was significantly associated with the shifts of one or more of five operating room technicians (OR, 2.9 to 6.8) who were responsible for preparing intravenous fluids used both to reconstitute perioperatively administered antibiotics and to prime central vascular catheter assemblies. CONCLUSIONS: Our findings are consistent with a pattern of intermittent contamination due to periodic breaches in sterile technique, rather than a point-source of contamination. The unique challenges that such a procedural breakdown presents to an epidemiologic investigation are discussed. This outbreak stresses the importance of providing comprehensive training in antisepsis when multifunctional personnel are incorporated into an operating room work environment.

Immunohistochemical detection of Aspergillus species in pediatric tissue samples.

Definitive diagnosis of invasive aspergillosis often requires tissue samples for histologic evidence of fungal infection and culture confirmation of Aspergillus species. However, the culture frequently fails to isolate Aspergillus species. Alternative approaches to confirm Aspergillus infection use polymerase chain reaction, in situ hybridization, and immunohistochemical analysis on paraffin-embedded sections. These approaches are well characterized in animals and adult patients but not pediatric patients. We studied the immunoreactivity of a commercially available monoclonal antibody, Mab-WF-AF-1 (DAKO, Carpinteria, CA), on paraffin-embedded sections from 16 pediatric cases with invasive aspergillosis, of which 12 were proven by culture. Optimal immunoreactivity required microwave antigen retrieval using high pH; 5 other antigen retrieval approaches were unsuccessful. With optimization, the monoclonal antibody was strongly immunoreactive in all cases with staining of the Aspergillus cell wall, septa, and cytoplasm. Background was minimal with no cross-reactivity to Candida albicans. These findings demonstrate the usefulness of the Mab-WF-AF-1 antibody in pediatric tissues suspected of invasive aspergillosis.

Risk of bacteremia in young children with pneumonia treated as outpatients.

BACKGROUND: Blood cultures are often obtained as part of the evaluation of children with pneumonia. There are few data regarding the risk of bacteremia with pneumonia in children since introduction of the Haemophilus influenzae type b vaccine. OBJECTIVE: To evaluate the risk of bacteremia in young children with pneumonia who were treated as outpatients. METHODS: A retrospective cohort study of 580 children aged 2 to 24 months who were evaluated by blood culture in a tertiary care children's hospital emergency department between February 1, 1993, and May 31, 1996, and discharged with the diagnosis of pneumonia. RESULTS: The mean patient age was 14.1 months; 339 patients (58.4%) were boys. Thirty-eight patients (6.6%) reported the use of oral antibiotics before initial emergency department evaluation. The prevalence of bacteremia was 1.6% (95% confidence interval, 0.7%-2.9%). Streptococcus pneumoniae was the causative organism in all 9 cases. The serotype was available for 8 of 9 cases. Six (75%) of 8 cases of S pneumoniae bacteremia were caused by serotypes included in the current heptavalent pneumococcal conjugate vaccine, which was not available at the time of this study. The contamination rate was 1.9% (95% confidence interval, 1.0%-3.4%). The mean +/- SD time to blood culture positive for organisms in a continuously monitored system was significantly shorter for pathogens (13.9 +/- 1.3 hours) than for contaminants (21.2 +/- 6.1 hours; P =.01). CONCLUSIONS: Children aged 2 to 24 months with pneumonia who are treated as outpatients are at low risk of bacteremia. Widespread use of the pneumococcal conjugate vaccine may further decrease the incidence of bacteremia in this population.