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A novel swine-origin influenza A subtype H1N1 virus, designated 2009 H1N1 influenza A, was identified as the cause of pandemic febrile respiratory illnesses [1–4]. Although individuals of all ages were affected, the greatest increase in severe morbidity and mortality occurred in young children, pregnant women, and the morbidly obese [5]. In human immunodeficiency virus type 1 (HIV-1)–infected patients, influenza infection is more severe than that typical of age-matched uninfected people [6, 7]. HIV-1–nfected patients also may shed virus for greater periods of time, prolonging the need for isolation in the clinic or hospital [8]. Because of the increased severity of this pandemic in children and young adults, knowledge of the safety and immunogenicity of the pandemic influenza A (pH1N1) 2009 monovalent vaccine in this population is critically important. Antibody responses to seasonal trivalent influenza vaccine (TIV) are blunted in HIV-1–infected children and adults who are not receiving antiretroviral therapy (ART) [9–11] but improved in patients who do not have progressive HIV-1 disease and/or are receiving combination ART (cART) [12–16]. Still, the immunological response is poorer compared to that of HIV-uninfected cohorts [15, 16]. Studies evaluating the effect of antigen dosage on the immune responses to TIV performed over the past 35 years demonstrate dose-related increases in serum and mucosal antibody responses [17–25]. Higher vaccine dosages are also associated with the development of higher levels of serum antibodies that recognize antigenically distinct drift variants [23] and can overcome suboptimal responses in immunologically impaired vaccinees, such as elderly patients [22, 24, 25]. However, higher dosages of hemagglutinin are also associated with more frequent adverse events. We hypothesized that 2 doses of influenza vaccine would be necessary to achieve protection in perinatally HIV-1–infected children and youth who had no prior exposure to pH1N1. In addition, because of blunted response to TIV in HIV-1–infected persons, we investigated a 30-μg dose of antigen, double the 15-μg dose proposed for healthy children.

The safety, toxicity, and pharmacokinetics of intrapartum and early newborn nevirapine were evaluated in 17 human immunodeficiency virus type 1-infected women in labor and their newborns. No adverse effects of nevirapine were noted in any study mothers or infants. Following maternal dosing with 200 mg during labor, concentrations exceeding 100 ng/mL (10 times the in vitro IC 50 ) were achieved in the newborns. Nevirapine elimination was prolonged in both mothers and infants, with median half-lives ranging from 36.8 to 65.7 h. Administration of 200 mg orally to the mothers in labor and of a single 2-mg/kg oral dose to the infants at 48-72 h after birth maintained serum concentrations in the infants >100 ng/mL through 7 days of life.

The current dosage of zidovudine for children is 180 mg/m2 every 6 h. To investigate whether a lower dosage was equally effective, human immunodeficiency virus (HIV)-infected children (3 months to 12 years) with mild to moderate symptoms were randomly assigned to receive either high-dose (180 mg/m2/dose) or low-dose (90 mg/m2/dose) zidovudine (double-blind). Treatments were compared with respect to neuropsychologic function, survival, clinical and laboratory evidence of disease progression, and safety and tolerance. Four hundred twenty-six HIV-infected children were enrolled; median time for receipt of study drug was 35 months. Zidovudine in either dose was well tolerated, with no difference in efficacy or tolerance by treatment group using any clinical or laboratory parameter. In children with mild to moderate disease, a reduction of zidovudine to 90 mg/m2/dose will result in substantial cost savings and should be the recommended dose.

The safety, tolerability, and pharmacokinetics of zalcitabine (ddC) in a single oral dose (0.02 mg/kg) was evaluated in 23 mildly symptomatic human immunodeficiency virus-infected children (mean age, 4.2 years). After administration of ddC, blood samples were obtained at 0.5, 1, 1.5, 2, 4, 6, and 8 h for analysis. The drug was well tolerated and no side effects were noted. Plasma ddC levels were determined by ion spray liquid chromatography/tandem mass spectrometry. ddC was rapidly absorbed, with a mean maximum plasma concentration of 9.3 ng/mL (range, 3.2-14.1) attained within a mean of 1 h (range, 0.5-2.0). Mean elimination half-life was 1.4 h (range, 1.0-3.5), mean area under the plasma concentration-time curve was 25 ng.h/mL (range, 11-37), and mean total body clearance was 14.6 mL/min/kg (range, 8.9-30.6). Plasma concentrations were lower and the half-life shorter in these children than in adults given comparable doses, suggesting that ddC may be cleared more rapidly in children than adults.

In prospective studies, tumor necrosis factor (TNF alpha) was detected in cerebrospinal fluid (CSF) of 33 of 38 children with bacterial meningitis (BM) but in none of 15 with viral meningitis/encephalitis (P less than .001). BM CSF TNF alpha (less than 35 to greater than 25,500 pg/ml) correlated with CSF bacterial density (P less than .01), CSF protein (P less than .001), endotoxin (LPS) in gram-negative disease (P less than .01), and consecutive febrile hospital days (P less than .001); initial CSF TNF alpha greater than 1000 pg/ml was associated with seizures (P less than .05). Only 5 children with BM (13%) had detectable plasma TNF alpha activity on admission. A higher proportion who died had detectable plasma TNF alpha activity compared with survivors (3/4 vs. 2/34, P less than .005). Platelet-activating factor (PAF) in CSF was higher in 19 children with Haemophilus influenzae meningitis than in 17 controls (P less than .01) and correlated with bacterial density (P less than .01), CSF LPS (P less than .01), CSF TNF alpha levels (P less than .01), and the Herson-Todd severity score (P less than .01). Elevated CSF TNF alpha and PAF are often present in children with BM and are associated with seizures and severity of disease. Detectable CSF TNF alpha appears to distinguish BM from viral meningitis.

Total, cell-free, and cell-bound endotoxin and bacterial density were measured in cerebrospinal fluid (CSF) of 22 children with Hemophilus influenzae meningitis. Also the effect of ceftriaxone on CSF endotoxin levels was investigated in eight patients by reexamining their CSF 2-6 h after the initial dose. Initial CSF bacterial density correlated with initial CSF endotoxin levels (P less than .001). Ceftriaxone induced a marked increase of free endotoxin in CSF, from an initial (mean +/- SE) 0.75 +/- 0.21 to 1.29 +/- 0.23 log10 ng/ml (P less than .01). This increase correlated positively with the number of bacteria killed in the CSF (P less than .01). The increase in free endotoxin was associated with an increase in mean CSF lactate levels from 8.5 to 9.7 units/l (P less than .05) and mean lactate dehydrogenase levels from 102 to 180 mmol/l (P less than .02) and a decrease in mean CSF glucose from 1.17 to 0.46 mmol/l (P less than .05). Initial CSF total endotoxin concentrations correlated both with the Herson-Todd clinical severity score (P less than .001) and with the number of febrile hospital days (P less than .001). These findings suggest that highly bactericidal agents initially lead to release of free endotoxin from gram-negative organisms into CSF, with associated enhanced inflammatory response by the host.

The presence of the human immunodeficiency virus type 1 (HIV) provirus was assessed in peripheral blood mononuclear cells (PBMCs) from 27 offspring of HIV-infected mothers, 12 of these mothers, and 4 HIV-uninfected mother-infant control pairs. Enzymatic amplification of specific conserved regions of the gag and env genes was performed directly in PBMC lysates using the polymerase chain reaction (PCR) technique. The enzymatically amplified gene products were evaluated using the oligomer hybridization detection procedure. PBMCs from infected infants (as determined by Centers for Disease Control clinical criteria) and from HIV-infected mothers manifested a characteristic HIV oligomer hybridization product. Clinically uninfected seropositive infants with declining HIV antibody titers and infants who became seronegative lacked an enzymatically amplified HIV gene product. These preliminary data indicate that PCR is a valuable diagnostic technique to detect or exclude HIV infection in young infants and children.

The predictive value of in vitro studies of antibiotic interaction for clinical drug interactions is unclear. Five clinical isolates (two Klebsiella, two Pseudomonas aeruginosa, and one Serratia marcescens) were evaluated by the time-kill curve method for in vitro synergy between amikacin and imipenem. When we used the stringent definition of synergy of Hallander et al., no synergy was present for any study strain; however, when we used a more-conventional definition of synergy, these drugs interacted synergistically against all study strains. The results of these in vitro studies were correlated with in vivo interactions by using neutropenic infant rats injected ip with study organisms and given various treatment regimens. For 80% of the study strains, treatment of rats with amikacin and imipenem resulted in significantly greater survival than did therapy with either drug alone or than could be predicted by addition of survival rates achieved with either agent alone (P less than .005). In vitro studies predicted this in vivo synergy in 80% of the cases when the more-conventional definition of synergy was used, whereas they were not predictive when the more-stringent definition of synergy was used. This rat model of neutropenia and gram-negative sepsis may provide more insight into in vivo drug interactions than do current methods.