Martha L. Lepow

Clinical evaluation of group A and group C meningococcal polysaccharide vaccines in infants.

Group A and group C meningoccal polysaccharide vaccines were evaluated in infants. No significant local or systemic reactions were observed with 908 doses of vaccine given to 396 infants between 3 and 12 mo of age. The antibody response varied with the age of the infant, vaccine dose, molecular weight of vaccine, prior immunization with vaccine, and prior exposure to naturally occurring cross-reactive antigens. Only 7% of 3-mo-old infants had detectable antibody responses to primary immunization with 5-200 mug of A vaccine, presumably because of suppressive effects of high concentrations of maternal anti-A. More than 90% of 7- and 12-mo-old infants responded to A vaccine, achieving geometric mean anti-A concentrations of 0.38 and 0.98 mug/ml, respectively. The dose-response curve was flat between 10 and 200 mug of A vaccine. Geometric mean anti-A concentrations of 2.51 and 4.00 mug/ml were induced in 7- and 12-mo-old infants by booster injections of A vaccine. Approximately 90% of 3-mo-old infants had detectable antibody responses to primary immunization with C vaccine. The 100-mug dose appeared to be optimal, resulting in geometric mean anti-C concentrations of 0.49, 1.55, and 2.64 mug/ml in 3-, 7-, and 12-mo-old infants, respectively. Significant booster responses were not observed with C vaccine. Indeed, except for the 10-mug dose, booster injections of C vaccine in 7- and 12-mo-old infants resulted in lower anti-C concentrations than did primary immunizations.

Deep Sequencing Reveals Mixed Infection with 2009 Pandemic Influenza A (H1N1) Virus Strains and the Emergence of Oseltamivir Resistance

Mixed infections with seasonal influenza A virus strains are a common occurrence and an important source of genetic diversity. Prolonged viral shedding, as observed in immunocompromised individuals, can lead to mutational accumulation over extended periods. Recently, drug resistance was reported in immunosuppressed patients infected with the 2009 pandemic influenza A (H1N1) virus within a few days after oseltamivir treatment was initiated. To better understand the evolution and emergence of drug resistance in these circumstances, we used a deep sequencing approach to survey the viral population from an immunosuppressed patient infected with H1N1/2009 influenza and treated with neuraminidase inhibitors. This patient harbored 3 genetic variants from 2 phylogenetically distinct viral clades of pandemic H1N1/2009, strongly suggestive of mixed infection. Strikingly, one of these variants also developed drug resistance de novo in response to oseltamivir treatment. Immunocompromised individuals may, therefore, constitute an important source of genetic and phenotypic diversity, both through mixed infection and de novo mutation.

Double blind placebo-controlled trial of pleconaril in infants with enterovirus meningitis

Background. Enterovirus (EV) meningitis is common in infants and may have neurologic complications. Treatment of older children and adults with pleconaril has been associated with reduced severity and duration of symptoms. This study evaluated the pharmacokinetics, safety and efficacy of pleconaril in infants with EV meningitis. Methods. Infants ≤12 months old with suspected EV meningitis were randomized 2:1 to receive pleconaril, 5 mg/kg/dose orally three times a day or placebo for 7 days. Evaluations included pharmacokinetic determinations, safety laboratory testing, serial culture and PCR assays and clinical evaluations. Results. Of 21 evaluable subjects 20 were confirmed with EV infection (12 pleconaril, 8 placebo). Among pleconaril-treated subjects 26 of 29 peak and trough pleconaril levels exceeded the 90% inhibitory concentration for EVs. A median 3.5-fold drug accumulation occurred between Days 2 and 7. Pleconaril was well-tolerated, although twice as many adverse events occurred per subject in the pleconaril group. Serial cultures from the oropharynx, rectum and serum had low yield (≤50%) and positivity generally persisted for <4 days in both groups. Serial PCR assays of culture-negative oropharyngeal and rectal specimens had high positivity rates (generally ≥50%) persisting through Day 14. No significant differences in duration of positivity by culture or PCR, hospitalization or symptoms were detected between groups. Conclusions. The dose of pleconaril studied provided sufficient plasma levels and was well-tolerated; however, drug accumulation was evident. The low yields of serial viral cultures, relatively short and benign clinical courses and the small number of subjects enrolled precluded demonstration of efficacy. If this medication is to be prescribed in infants, surveillance for toxicity related to drug accumulation will be necessary.

Prevention of gram-positive sepsis in neonates weighing less than 1500 grams

A prospective, randomized study to evaluate the effectiveness of a continuous low-dose vancomycin infusion to prevent nosocomial gram-positive bacteremia was initiated within the first 2 weeks of life in neonates weighing < 1500 gm. Seventy-one infants received constant infusion of vancomycin (25 micrograms/ml) mixed with their total parenteral nutrition solution; 70 infants served as control subjects. The groups were clinically similar in birth weight, estimated gestational age, and severity of illness. Administration of vancomycin was begun at a mean age of 5.4 +/- 2.9 days. Infants had mean serum vancomycin concentrations of 2.4 micrograms/ml, and received vancomycin for a mean of 11 +/- 7 days. No vancomycin-resistant organisms were detected in surveillance cultures during the 2-year study period. Twenty-four of seventy control infants, in comparison with 1 of 71 infants receiving vancomycin, had gram-positive bacteremia (p < 0.001). The addition of a low dose of vancomycin to alimentation fluids virtually eliminated the incidence of gram-positive bacteremia in an at-risk population of very low birth weight infants. However, the widespread use of vancomycin in total parenteral nutrition solution is not recommended until better data on the emergence of vancomycin-resistant organisms are available.

The impact of an enteroviral RT-PCR assay on the diagnosis of aseptic meningitis and patient management

BACKGROUND Enterovirus (EV) is a major cause of aseptic meningitis and non-specific febrile illness in children. Since the majority of patients are hospitalized for possible bacterial infection, a rapid test for the diagnosis of enteroviral meningitis (EVM) may reduce hospitalizations and unnecessary treatments. OBJECTIVE To review the impact of an EV reverse transcriptase-polymerase chain reaction (RT-PCR) assay for the diagnosis of EVM on patient management. STUDY DESIGN CSF from 1056 patients admitted to the hospital between 1998 and 2001 was tested using EV RT-PCR. The results were correlated with CSF counts, diagnosis, test turnaround time (TAT) and length of hospital stay (LOS). RESULTS EV RT-PCR was positive for 113 patients (11%). Of these cases, 92% occurred during the summer months and 77% were in children <19 years of age. Children <3 years old with EVM frequently had non-specific clinical findings and lacked pleocytosis. There was a significant correlation between decreasing LOS and TAT (r(2)=0.97, P<0.001). CONCLUSION RT-PCR testing for EVM is an important tool to aid in the diagnosis of children with non-specific febrile illness. This test impacted patient management as measured by shortened patient stays, which should translate into significant health care savings.

Potential Mechanisms for Failure to Eradicate Group A Streptococci From the Pharynx

Objective. To investigate the relative efficacy of orally administered cefadroxil and penicillin V in the treatment of group A streptococcal (GABHS) pharyngitis and the mechanism(s) responsible for failure of antimicrobial therapy to eradicate GABHS from the pharynx. Study Design. A prospective, randomized clinical trial was conducted in four pediatric offices in which 462 patients with acute pharyngitis and positive culture for GABHS were randomly assigned to receive cefadroxil (n = 232) or penicillin V (n = 230). Results. Bacteriologic treatment success rates for patients in cefadroxil and penicillin groups were 94% and 86%, respectively. However, among patients classified clinically as likely to have bona fide GABHS pharyngitis, there was no difference in bacteriologic treatment success rates in cefadroxil and penicillin groups (95% and 94%, respectively). Among patients classified clinically as likely to be streptococcal carriers, bacteriologic treatment success rates in cefadroxil and penicillin groups were 92% and 73%, respectively. The presence of β-lactamase and/or bacteriocin-producing pharyngeal flora had no consistent effect on bacteriologic eradication rates among patients in either penicillin or cefadroxil treatment groups or among patients classified as having either GABHS pharyngitis or streptococcal carriage. Conclusions. Neither β-lactamase nor bacteriocin produced by normal pharyngeal flora are related to bacteriologic treatment failures in GABHS pharyngitis. Cefadroxil seems to be more effective than penicillin V in eradicating GABHS from patients classified as more likely to be streptococcal carriers. However, among patients we classified as more likely to have bona fide GABHS pharyngitis, the effectiveness of cefadroxil and penicillin V seems to be comparable.

Safety and immunogenicity of haemophilus influenzae type b-polysaccharide diphtheria toxoid conjugate vaccine in infants 9 to 15 months of age†

Sixty 9- to 15-month-old infants were randomly assigned to receive two doses, 1 month apart, of a Haemophilus influenzae type b capsular polysaccharide-diphtheria toxoid conjugate vaccine (PRP-D) or PRP vaccine, each containing 20 micrograms PRP. There were no significant local or systemic reactions. After one dose of PRP-D, 93% of the subjects attained levels of greater than or equal to 0.15 microgram/ml and 59% achieved greater than or equal to 1 microgram/ml antibody protein. These percentages rose to 100% and 86%, respectively, after the second dose, at which time the geometric mean titer of anti-PRP antibody was 4.8 micrograms/ml. IgG anti-PRP levels were 4.3 times higher than IgM. The proportion of IgG to IgM antibody induced by PRP-D increased with age. After two doses, 33% of the PRP recipients responded with a level of greater than or equal to 0.15 microgram/ml and only 19% responded to a level of greater than or equal to 1.0 microgram/ml. One year later, all of the PRP-D recipients tested still had greater than or equal to 0.15 microgram/ml and more than half had greater than or equal to 1.0 microgram/ml antibody protein.

Candida albicans arthritis one year after successful treatment of fungemia in a healthy infant

Fungal arthritis in pediatric patients is rare and is most often associated with hematogenous spread to the affected joint. It is generally seen concomitant with, or shortly after, fungemia. We report a case of an immunocompetent patient in whom candidal arthritis developed 1 year after initial fungemia. The initial candidiasis was considered to be adequately treated with amphotericin B. The Candida isolates from the neonatal fungemia and subsequent arthritis were the some as identified by electrophoretic karyotype, restriction fragment length polymorphism analysis, and antifungal susceptibility testing. Pediatric candidal fungemia, arthritis, and their treatments are discussed.

Normal Fibronectin Levels as a Function of Age in the Pediatric Population

Summary: Fibronectin is an important non-immune opsonic protein influencing phagocytic clearance of blood-borne nonbacterial particulates which may arise in association with septic shock, tissue injury, and intravascular coagulation. In the present study, serum fibronectin was measured by both electroimmunoassay as well as rapid immunoturbidimetric assay in healthy children (n = 114) ranging in age from 1 month to 15 years in order to delineate the temporal alterations in fibronectin with age. Normal adult serum fibronectin concentrations are typically 220 μg/ml ± 20 μg/ml. Serum concentration is 35–40% lower than normal plasma concentration due to the binding of fibronectin to fibrin during clot formation. Children between 1–12 months of age bad significantly (P < 0.05) lower serum fibronectin levels than children between the ages of 1–15 years. Progressive elevation in fibronectin levels was observed within the last 8 months of the first year of age. Fibronectin levels in children older than 1 year of age remained constant up to 15 years and were within the lower limit of the normal adult concentration. No significant (P > 0.05) difference in serum fibronectin was observed between male and female children at all age groups. Fibronectin levels thus, increase during the first year of age and normal levels of this blood protein in the infant are less than the normal range for adults.

Persistence of antibody and response to booster dose of Haemophilus influenzae type b polysaccharide diphtheria toxoid conjugate vaccine in infants immunized at 9 to 15 months of age

At approximately 2 years of age, 27 infants previously immunized at 9 to 15 months of age with two doses of polyribosylribitol phosphate-diphtheria toxoid conjugate vaccine (PRP-D) and 23 infants immunized with polyribosylribitol phosphate (PRP) vaccine were given a single injection of PRP-D. Pre- and post-immunization sera were obtained. No serious local or systemic reactions were observed. The PRP-D recipients had a geometric mean anti-PRP antibody level of 4.8 micrograms/ml 1 month after the second primary injection, retained 1.2 microgram/ml 1 year later, and had a level of 71 micrograms/ml after the booster immunization. In contrast, PRP recipients had a geometric mean level of 0.083 microgram/ml 1 month after the second primary injection, retained 0.042 microgram/ml 1 year later, and after a single dose of PRP-D at approximately 2 years of age had a geometric mean level of 8.6 micrograms/ml. The significantly higher antibody response in the prior PRP-D recipients suggests the recall of immunologic memory induced by the PRP-D vaccine.