Infection with Sin Nombre hantavirus: clinical presentation and outcome in children and adolescents.

OBJECTIVE: Sin Nombre hantavirus (SNV) is the leading causative agent of hantavirus cardiopulmonary syndrome (HCPS) in the United States and Canada. Relatively few cases of HCPS have involved children. This report describes the clinical characteristics of a series of pediatric cases of SNV infection in the United States and Canada from 1993 through March 2000. METHODS: We analyzed clinical and laboratory data on 13 patients who were 85% of patients had elevated levels of serum aspartate aminotransferase, alanine aminotransferase, and hypoalbuminemia. Leukocytosis and hemoconcentration were seen in less than one third of patients at admission. HCPS developed in 12 of the 13 patients (92%), and 4 of those 12 died (33% case-fatality ratio). The majority of HCPS patients (8 of 12 [67%]) were critically ill and required mechanical ventilation. Extracorporeal membrane oxygenation was used in 2 patients, 1 of whom survived. An elevated prothrombin time (>/=14 seconds) at admission was predictive of mortality. CONCLUSIONS: Infection with SNV in children and adolescents causes HCPS with a clinical course and mortality rate similar to that described in adults. We believe that early recognition of HCPS in children and adolescents and appropriate referral to tertiary care centers that are experienced with HCPS are important in reducing mortality.

American Academy of Pediatrics. Committee on Infectious Diseases. Technical report: prevention of pneumococcal infections, including the use of pneumococcal conjugate and polysaccharide vaccines and antibiotic prophylaxis.

Pneumococcal infections are the most common invasive bacterial infections in children in the United States. The incidence of invasive pneumococcal infections peaks in children younger than 2 years, reaching rates of 228/100,000 in children 6 to 12 months old. Children with functional or anatomic asplenia (including sickle cell disease [SCD]) and children with human immunodeficiency virus infection have pneumococcal infection rates 20- to 100-fold higher than those of healthy children during the first 5 years of life. Others at high risk of pneumococcal infections include children with congenital immunodeficiency; chronic cardiopulmonary disease; children receiving immunosuppressive chemotherapy; children with immunosuppressive neoplastic diseases; children with chronic renal insufficiency, including nephrotic syndrome; children with diabetes; and children with cerebrospinal fluid leaks. Children of Native American (American Indian and Alaska Native) or African American descent also have higher rates of invasive pneumococcal disease. Outbreaks of pneumococcal infection have occurred with increased frequency in children attending out-of-home care. Among these children, nasopharyngeal colonization rates of 60% have been observed, along with pneumococci resistant to multiple antibiotics. The administration of antibiotics to children involved in outbreaks of pneumococcal disease has had an inconsistent effect on nasopharyngeal carriage. In contrast, continuous penicillin prophylaxis in children younger than 5 years with SCD has been successful in reducing rates of pneumococcal disease by 84%. Pneumococcal polysaccharide vaccines have been recommended since 1985 for children older than 2 years who are at high risk of invasive disease, but these vaccines were not recommended for younger children and infants because of poor antibody response before 2 years of age. In contrast, pneumococcal conjugate vaccines (Prevnar) induce proposed protective antibody responses (>.15 microg/mL) in >90% of infants after 3 doses given at 2, 4, and 6 months of age. After priming doses, significant booster responses (ie, immunologic memory) are apparent when additional doses are given at 12 to 15 months of age. In efficacy trials, infant immunization with Prevnar decreased invasive infections by >93% and consolidative pneumonia by 73%, and it was associated with a 7% decrease in otitis media and a 20% decrease in tympanostomy tube placement. Adverse events after the administration of Prevnar have been limited to areas of local swelling or erythema of 1 to 2 cm and some increase in the incidence of postimmunization fever when it is given with other childhood vaccines. Based on data in phase 3 efficacy and safety trials, the US Food and Drug Administration has provided an indication for the use of Prevnar in children younger than 24 months.

Infections and immunizations of children with sickle cell disease.

Children with SCD are prone to invasive infections caused by S. pneumoniae and H. influenzae. Osteomyelitis is caused most often by Salmonella species and less often by S. aureus. The chest syndrome and its associated microvascular disease carry a risk of prolonged and severe infections for Mycoplasma, Chlamydia, and probably other lower respiratory pathogens, particularly in the group of children with SCD prone to pain or microvascular sequestration, such as those with SC hemoglobinopathy. Despite three decades of investigation, the immunopathologic mechanisms leading to these increased risks is not completely clear. Bone infarction and microvascular disease probably play a part in the predisposition to osteomyelitis. Dysfunctional IgG and IgM antibody response, a lack of splenic clearance, defects in alternative pathway fixation of complement, and opsonophagocytic dysfunction play a role in the predisposition to invasive infection from polysaccharide-encapsulated organisms. Immunization with the conjugate Haemophilus vaccines has largely controlled infections caused by this pathogen. Early recognition of SCD through neonatal screening allows early and vigorous antibiotic management of febrile episodes in children with SCD and has perhaps provided the greatest benefit. Treatment of acute febrile episodes should include antibiotics active against regional strains of S. pneumoniae and H. influenzae, whereas treatment of febrile lower respiratory infections should include macrolide antibiotics that are active against Chlamydia and Mycoplasma, as well as pneumococci and Haemophilus. To date, no convincing evidence exists for the efficacy of pneumococcal polysaccharide vaccines in children with SCD, but preliminary data with the conjugate pneumococcal vaccines in normal children and those with SCD suggest that they may be as successful as Haemophilus vaccines in controlling this infection once they are available. Prophylaxis with daily penicillin administration is recommended and is well founded on clinical trials. However, problems with pneumococcal penicillin resistance and the association of failure with a lack of compliance to antibiotic regimens will dictate continued reexamination of this modality for the prevention of pneumococcal infections.

Immunogenicity and safety of Haemophilus influenzae type b polysaccharide-Neisseria meningitidis conjugate vaccine in 7.5 micrograms liquid formulation: a comparison of three lots with the 15.0 micrograms lyophilized formulation. Study Group for 7.5 micrograms Liquid PedvaxHIB.

We conducted a multicenter, single-blind, randomized comparisons of the immunogenicity and safety of three manufacturing-scale lots of 7.5 micrograms liquid Haemophilus influenzae type b polysaccharide- Neisseria meningitidis conjugate vaccine (PRP-OMPC) and a single lot of 15.0 micrograms lyophilized PRP OMPC. A total of 908 infants were entered into the study. Each infant received two primary injections intramuscularly 2 months apart beginning at age 2-6 months and a booster injection at 12-15 months. Blood samples for serology were obtained before each injection and 1 month after the second and the booster dose. Immune responses were measured by radioimmunoassay. Approximately 80% of the infants achieved a titer > 1.0 micrograms ml-1 after the second primary dose of all four lots tested: the geometric mean titer (GMT) was ca 3 micrograms ml-1 for each vaccine group. After the booster dose, more than 90% of infants from each vaccine group had a titer > 1.0 microgram ml-1;GMTs ranged from 8 to 10 micrograms ml-1. No serious vaccine-associated adverse reactions were reported. Thus the 7.5 liquid PRP OMPC vaccine was at least as immunogenic and well tolerated as the 15.0 micrograms lyophilized vaccine.

Granulocyte colony-stimulating factor as a marker for bacterial infection in neonates.

OBJECTIVE: To evaluate granulocyte colony-stimulating factor (G-CSF) as an early marker of bacterial or fungal infection in neonates. STUDY DESIGN: We measured G-CSF levels in infants of varying gestational and postnatal ages. We separated the infants into three groups: group 1, positive bacterial or fungal blood culture result; group 2, negative blood culture result but evidence of clinical sepsis; and group 3, negative blood culture result and no or weak evidence of sepsis. Comparison of mean G-CSF levels by group was accomplished by an analysis of variance. RESULTS: One hundred seventy-six evaluations for sepsis were done for 156 infants with gestational ages ranging from 24 to 43 weeks; 50% of these infants were less than 35 weeks of gestational age. The mean G-CSF levels of groups 1 and 2 were significantly higher than those of group 3. The mean G-CSF level of each group was 2278 pg/ml (group 1), 1873 pg/ml (group 2), and 280 pg/ml (group 3) (p < 0.001). On the basis of a cutoff level of 200 pg/ml, the sensitivity of the test was 95%, specificity 73%, positive predictive value 40%, and negative predictive value 99%. CONCLUSION: G-CSF levels represent a sensitive marker of infection in neonates of all gestational ages.

Intramuscular versus oral antibiotic therapy for the prevention of meningitis and other bacterial sequelae in young, febrile children at risk for occult bacteremia.

Because studies of the treatment of children with occult bacteremia have yielded conflicting results, we compared ceftriaxone with amoxicillin for therapy. Inclusion criteria were age 3 to 36 months, temperature > or = 39 degrees C, an acute febrile illness with no focal findings or with otitis media (6/10 centers), and culture of blood. Subjects were randomly assigned to receive either ceftriaxone, 50 mg/kg intramuscularly, or amoxicillin, 20 mg/kg/dose orally for six doses. Of 6733 patients enrolled, 195 had bacteremia and 192 were evaluable: 164 Streptococcus pneumoniae, 9 Haemophilus influenzae type b, 7 Salmonella, 2 Neisseria meningitidis, and 10 other. After treatment, three patients receiving amoxicillin had the same organism isolated from their blood (two H. influenzae type b, one Salmonella) and two from the spinal fluid (two H. influenzae type b), compared with none given ceftriaxone. Probable or definite infections occurred in three children treated with ceftriaxone and six given amoxicillin (adjusted odds ratio 0.43, 95% confidence interval 0.08 to 1.82, p = 0.31). The five children with definite bacterial infections (three meningitis, one pneumonia, one sepsis) received amoxicillin (adjusted odds ratio 0.00, 95% confidence interval 0.00 to 0.52, p = 0.02). Fever persisted less often with ceftriaxone (adjusted odds ratio 0.52, 95% confidence interval 0.28 to 0.94, p = 0.04). Although the difference in total infections was not significant, ceftriaxone eradicated bacteremia, prevented significantly more definite focal bacterial complications, and was associated with less persistent fever.

Infection caused by Streptococcus pneumoniae in children with sickle cell disease: epidemiology, immunologic mechanisms, prophylaxis, and vaccination.

The incidence of invasive infection due to Streptococcus pneumoniae is 6.9 infections per 100 patient-years among children with sickle cell anemia (SS genotype) who are less than 5 years of age; this rate is 30-100 times that which would be expected in a healthy population of this age. Splenic dysfunction is the major contributor to the increased risk. Postulated abnormalities of immunologic defense mechanisms, including synthesis of polyclonal IgG and IgM, the alternative complement pathway, opsonic activity, and T and B cell interaction, may also enhance risk. Preceding or concomitant viral infection is suspected of predisposing to pneumococcal infection, but no definitive data are available. The most prevalent pneumococcal serotypes causing disease in this setting include types 6, 14, 18, 19, and 23; these same serotypes are most frequently involved in "vaccine failure." Current evidence demonstrates only modest protective efficacy for contemporary pneumococcal vaccines in young patients with sickle cell anemia; thus alternative vaccines are required. Convincing evidence for a protective effect of antibiotic prophylaxis has been obtained in limited time trials. However, presently used prophylactic regimens pose problems related to compliance and provide imperfect protection; moreover, their optimal duration remains unknown.

Polysaccharide encapsulated bacterial infection in sickle cell anemia: a thirty year epidemiologic experience.

Annual age-specific incidence rates of Streptococcus pneumoniae or Haemophilus influenzae bacterial septicemia in sickle cell anemia (SS) were determined for the years of 1957 through 1989. Forty-nine patients had 64 episodes of septicemia among a population of 786 SS patients observed for 8,138 person-years. Peak frequency of infection occurred between 1968-1971 and 1975-1981 with a conspicuous absence of episodes in 1972, 1973, 1982-1984, and 1986-1987, thus demonstrating cycles of high and low attack rates. The annual age-specific incidence rate of septicemia varied from 64.5 (1965) to 421.1 (1980) per 1,000 person-years for those under 2 years of age and never exceeded 10.2 per 1,000 in those over 4 years of age. Following the introduction of pneumococcal polyvalent vaccine in 1978, incidence of infection decreased in SS children greater than 2 years of age. No modification of the risk of infection was observed in immunized children less than 2 years of age. During these three decades, there has been a ten-fold increase in the number of SS adults over 20 years of age. The relative risk of chronic sickle complications comparing the survivors of septicemia to the non-infected patients was: subsequent death 1.76, retinopathy 4.06, avascular necrosis 1.95, symptomatic cholelithiasis 1.33, stroke 1.30, and priapism 1.26. These data suggest that prognosis for lifetime severe SS is initially manifested as an increased risk of septicemia during childhood.

Antibacterial activity of crotalid venoms against oral snake flora and other clinical bacteria.

Despite heavy oral and fang contamination of crotalid species with a wide variety of potentially pathogenic bacteria, crotalid envenomation is associated with a low incidence of bacterial infection. Minimal inhibitory and bactericidal concentrations of venoms from three crotalid species were determined against six aerobic and eight anaerobic reference and oral crotalid microorganisms. All anaerobic isolates were resistant to greater than 20,480 micrograms/ml, whereas variable activity (range, 5-20,480 micrograms/ml) was observed for aerobic strains. Further studies against other aerobic clinical isolates demonstrated that venom had the greatest activity (MIC, less than or equal to 80 micrograms/ml) against staphylococci, Pseudomonas aeruginosa, and Enterobacter, Citrobacter, Proteus, and Morganella species. Inhibitory activity was lost with prolonged incubation for many gram-negative species. Crotalid venoms are broadly active against aerobic gram-negative and -positive bacteria. This activity may play a role in the low incidence of infection after envenomation injuries.

Phage typing of Staphylococcus intermedius.

Staphylococcus intermedius, a coagulase-positive staphylococcal species, is a common canine pathogen and a rare human wound pathogen. A total of 145 strains of S. intermedius (ATCC 29663, 4 reference strains, 4 human isolates, 44 canine infection isolates, and 92 isolates from canine gingiva) were screened for lysogenic phage by a modified Fisk method. Nineteen phage preparations were prepared for preliminary typing experiments. Lytic activity was observed on 93 of 145 (64.1%) isolates, yielding 44 lytic patterns with individual strains susceptible to one or more phages. Five phages lysed only a single strain, but lytic patterns varied from 1 to 11 lytic phages per isolate. A distinct lytic pattern did not separate canine or human wound isolates from canine gingival isolates. All human wound isolates fell into the two most common canine gingival or wound patterns; the single human nasopharyngeal isolate was not lysed by any phage. Twenty-two of 44 (55%) canine wound isolates and 65 of 92 (71%) gingival isolates yielded lytic patterns. Lysogenic phages are common in S. intermedius. This preliminary study suggests that phage typing may be a useful tool in distinguishing epidemiologically related strains.

Antibiotic treatment of community acquired bacterial meningitis.

Community acquired meningitis is predominantly caused by three agents: Haemophilus influenzae, Streptococcus pneumoniae and Neisseria meningitidis Four physical properties of available drugs--molecular size, protein binding, lipid solubility and ionization--affect drug entry to the central nervous system (CNS). These factors, coupled with acute changes in blood-brain barriers and intrinsic bactericidal activity, have a bearing on the success of treatment with all agents. Third generation cephalosporins have largely supplanted older regimens due to their intrinsic qualities of greater bactericidal activity, optimal cerebrospinal fluid pharmacokinetics, and low toxicity. The pharmacological principles of treatment of CNS bacterial infections, pharmacology of available drugs, and current treatment recommendations are reviewed.

Cefuroxime treatment failure of nontypable Haemophilus influenzae meningitis associated with alteration of penicillin-binding proteins.

A 10-year-old boy presented with nuchal rigidity and cerebrospinal fluid (CSF) leukocytosis initially and again on day 6 of intravenous cefuroxime therapy (200 mg/kg/day). Both CSF specimens yielded nontypable beta-lactamase-negative Haemophilus influenzae that were susceptible by disk tests but relatively resistant to cefuroxime (MIC, 8- to 16-fold greater than that of control isolates). To define the mechanism of resistance, the cefuroxime resistance marker was transformed to a susceptible H. influenzae recipient; inactivation and permeability of beta-lactam substrate were tested and the penicillin-binding protein (PBP) profiles were examined. Inactivation of beta-lactam substrate was not detected and reduced permeability was not found. However, reduced beta-lactam binding to PBPs 4 and 5 was observed; 18- to 27-fold more penicillin and 2.5-to 4-fold more cefuroxime was required to saturate or block 50% of the binding sites of these PBPs, respectively. Thus, reduced affinity of PBPs 4 and 5 for beta-lactam substrate appears to be the mechanism of cefuroxime resistance in this strain. The reduced affinity of these targets appears to have contributed to the bacteriologic and clinical failure in this patient.