Surveillance of pneumococcal colonization and invasive pneumococcal disease reveals shift in prevalent carriage serotypes in Massachusetts' children to relatively low invasiveness

BACKGROUND

Following the introduction of pneumococcal conjugate vaccines (PCV), overall nasopharyngeal colonization rates have not changed significantly, however a dramatic and sustained decline in invasive pneumococcal disease (IPD) in children was observed in every setting where the PCVs were implemented. We aimed to describe the differences in invasive disease potential of serotypes that are common colonizers in pre- and post-vaccine eras in order to provide further insight in our understanding of dynamic epidemiology of pneumococcal diseases.

METHODS

Using data from surveillance of nasopharyngeal carriage and enhanced surveillance for IPD, a serotype specific "invasive capacity (IC)" was computed by dividing the incidence of IPD due to serotype x by the carriage prevalence of that same serotype in children <7years of age in Massachusetts. We have evaluated the serotype specific invasive capacity in two periods; pre-PCV13 (2001/02, 2003/04, 2006/07, 2008/09) and post-PCV13 (2010/11 and 2013/14), and by age groups; <24monthsvs. ≥24months.

RESULTS

An approximate 50-fold variation in the point estimate was observed between the serotypes having the highest (7F, 38, 19A, 3, 33F) and the lowest (6C, 35B, 21, 11A, 23B and 23A) computed serotype specific invasive disease potential. In the post-PCV13 era (6C, 35B, 11A, 23B and 23A), 5 of the 7 most common serotypes colonizing the nasopharynx were serotypes with the lowest invasive capacity. Serotype specific invasive capacity trended down in older children for majority of the serotypes, and serotypes 3, 10A and 19A had significantly lower invasive capacity in children older than 24months of age compared to younger children.

CONCLUSION

Invasive capacity differs among serotypes and likely by age. Point estimates of IC for most of the common serotypes colonizing children in Massachusetts in post-PCV13 era were low and likely explain the continued reduction in IPD from the pre-PCV era in the absence of specific protection against these serotypes.

Clonal replacement among 19A Streptococcus pneumoniae in Massachusetts, prior to 13 valent conjugate vaccination

As part of an ongoing study of the response of the Streptococcus pneumoniae population to conjugate vaccination, we applied multi-locus sequence typing (MLST) to 291 isolates sampled from nasopharyngeal carriage in Massachusetts children. We found 94 distinct sequence types (STs), including 19 that had not been previously recorded, and a xpt allele containing a large insertion. Comparison with a similar sample collected in 2007 revealed no significant overall difference in the ST composition (p=0.51) suggesting that the population has reached a new equilibrium following the introduction of 7 valent vaccination in 2000. Within serotypes, a large and statistically significant increase (p=0.014 Fisher's Exact test) was noted in the prevalence of the major multiresistant clone ST 320, which is apparently outcompeting ST 199 among serotype 19A strains. This sample will be used as a baseline to study the future evolution of the pneumococcal population in Massachusetts following introduction of vaccines with higher valency.

Otitis media across nine countries: disease burden and management

OBJECTIVE

To assess the perceived disease burden and management of otitis media (OM) among an international cohort of experienced physicians.

METHODS

A cross-sectional survey conducted in France, Germany, Spain, Poland, Argentina, Mexico, South Korea, Thailand and Saudi Arabia. Face-to-face interviews conducted with 1800 physicians (95% paediatricians, 5% family practitioners).Main outcome measures were the perceived burden on clinical practice (number of cases, complications and referrals) and first- and second-line management strategies for OM. Results are expressed as mean and range across the nine countries over three continents.

RESULTS

Respondents estimated an average annual caseload of 375 (range 128-1003) children under 5 years of age with OM; 54% (range 44-71%) with an initial episode and 38% (range 27-54%) with recurrent OM (ROM). OM with complications was estimated to be approximately 20 (range 7-49) cases per year and an estimated 15% (8-41%) of children with OM was recalled as needing specialist referral. There was high awareness of Streptococcus pneumoniae and Haemophilus influenzae as causative bacterial pathogens: 77% (range 65-91%) and 74% (range 68-83%), respectively, but less recognition of non-typeable H. influenzae (NTHi); 59% (range 45-67%). Although concern over antimicrobial resistance was widespread, empirical treatment with antibiotics was the most common first-line treatment (mean 81%, range 40-96%). The burden of disease is substantial enough that many physicians would consider vaccination to prevent OM (mean score 5.1, range 4.3-6.2 on 1-7 scale).

CONCLUSIONS

This large, multinational survey shows that OM remains a significant burden for clinical practice. Despite awareness of shortcomings, antimicrobial therapy remains the most frequent treatment for OM.

Serotype specific invasive capacity and persistent reduction in invasive pneumococcal disease

Defining the propensity of Streptococcus pneumoniae (SP) serotypes to invade sterile body sites following nasopharyngeal (NP) acquisition has the potential to inform about how much invasive pneumococcal disease (IPD) may occur in a typical population with a given distribution of carriage serotypes. Data from enhanced surveillance for IPD in Massachusetts children ≤7 years in 2003/04, 2006/07 and 2008/09 seasons and surveillance of SP NP carriage during the corresponding respiratory seasons in 16 Massachusetts communities in 2003/04 and 8 of the 16 communities in both 2006/07 and 2008/09 were used to compute a serotype specific "invasive capacity (IC)" by dividing the incidence of IPD due to serotype x by the carriage prevalence of that same serotype in children of the same age. A total of 206 IPD and 806 NP isolates of SP were collected during the study period. An approximate 50-fold variation in the point estimates between the serotypes having the highest (18C, 33F, 7F, 19A, 3 and 22F) and lowest (6C, 23A, 35F, 11A, 35B, 19F, 15A, and 15BC) IC was observed. Point estimates of IC for most of the common serotypes currently colonizing children in Massachusetts were low and likely explain the continued reduction in IPD from the pre-PCV era in the absence of specific protection against these serotypes. Invasive capacity differs among serotypes and as new pneumococcal conjugate vaccines are introduced, ongoing surveillance will be essential to monitor whether serotypes with high invasive capacity emerge (e.g. 33F, 22F) as successful colonizers resulting in increased IPD incidence due to replacement serotypes.

Evolution and transmission of stable CTL escape mutations in HIV infection

Increasing evidence indicates that potent anti-HIV-1 activity is mediated by cytotoxic T lymphocytes (CTLs); however, the effects of this immune pressure on viral transmission and evolution have not been determined. Here we investigate mother-child transmission in the setting of human leukocyte antigen (HLA)-B27 expression, selected for analysis because it is associated with prolonged immune containment in adult infection. In adults, mutations in a dominant and highly conserved B27-restricted Gag CTL epitope lead to loss of recognition and disease progression. In mothers expressing HLA-B27 who transmit HIV-1 perinatally, we document transmission of viruses encoding CTL escape variants in this dominant Gag epitope that no longer bind to B27. Their infected infants target an otherwise subdominant B27-restricted epitope and fail to contain HIV replication. These CTL escape variants remain stable without reversion in the absence of the evolutionary pressure that originally selected the mutation. These data suggest that CTL escape mutations in epitopes associated with suppression of viraemia will accumulate as the epidemic progresses, and therefore have important implications for vaccine design.

Constancy of distribution of serogroups of invasive pneumococcal isolates among children: experience during 4 decades

Serogroups of pneumococci that caused bacteremia or meningitis in children were examined from 1981 through 1998 at Boston City Hospital/Boston Medical Center. There were 410 episodes of pneumococcal bacteremia (13--36 cases per year), of which 14 occurred in human immunodeficiency virus (HIV)--infected children and 9 occurred in children with sickle-cell disease. The 7 most common serogroups were 14 (30.7% of isolates), 19 (11.7%), 6 (11%), 18 (10.7%), 9 (7.6%), 23 (7.3%), and 4 (5.6%). The rate of episodes due to serogroups 4, 6, 9, 14, 18, 19, and 23 ranged from 80% to 91.9% during the study period. The rate of episodes due to serogroups 4, 6, 14, 18, 19, and 23 was 84.6% among patients with HIV infection, 100% among patients with sickle-cell disease, and 94.1% among the 18 patients for whom cultures of CSF specimens revealed pneumococcal meningitis. The results demonstrate that type 14 was the dominant pneumococcal serogroup responsible for invasive disease throughout the 18-year study period and that serogroup distribution overall remained constant. A comparison of these findings with historical pediatric data from our institution showed serogroup stability dating back to 1957.

Radiographic resolution of lymphocytic interstitial pneumonitis (LIP) in children with human immunodeficiency virus (HIV): not a sign of clinical deterioration

BACKGROUND

The literature and anecdotal evidence associate the resolution of radiographic findings of lymphocytic interstitial pneumonitis (LIP) with a decline in immune and clinical status of human immunodeficiency virus (HIV) infected children.

OBJECTIVE

As our clinical impression was the opposite, we sought to elucidate this contradiction.

MATERIALS AND METHODS

Of 52 pediatric patients infected with the HIV currently being followed at our institution, 20 (38.5%) carried the diagnosis of LIP and 13 (65%) of these have had complete resolution of radiographic findings of LIP. We retrospectively reviewed the chest radiographs, CD4 counts, and clinical history of these 13 patients.

RESULTS

Of the 13 patients who had resolution of radiographic findings, 11 (84.6%) had no significant change in CD4 count at the time of resolution and remained clinically stable during a mean follow-up period of 32 months. Two patients (15.3%) developed severe CD4 lymphocytopenia at the time of resolution of LIP, but clinically remained stable. None of these 13 patients had a recurrence of LIP, even with subsequent increases in CD4 count.

CONCLUSION

We suggest that in contradiction to previously published data, resolution of LIP on chest radiographs is not an indicator for poor prognosis for the HIV-infected pediatric patient.

Functionally inert HIV-specific cytotoxic T lymphocytes do not play a major role in chronically infected adults and children

The highly sensitive quantitation of virus-specific CD8(+) T cells using major histocompatibility complex-peptide tetramer assays has revealed higher levels of cytotoxic T lymphocytes (CTLs) in acute and chronic virus infections than were recognized previously. However, studies in lymphocytic choriomeningitis virus infection have shown that tetramer assays may include measurement of a substantial number of tetramer-binding cells that are functionally inert. Such phenotypically silent CTLs, which lack cytolytic function and do not produce interferon (IFN)-gamma, have been hypothesized to explain the persistence of virus in the face of a quantitatively large immune response, particularly when CD4 help is impaired. In this study, we examined the role of functionally inert CTLs in chronic HIV infection. Subjects studied included children and adults (n = 42) whose viral loads ranged from <50 to >100,000 RNA copies/ml plasma. Tetramer assays were compared with three functional assays: enzyme-linked immunospot (Elispot), intracellular cytokine staining, and precursor frequency (limiting dilution assay [LDA]) cytotoxicity assays. Strong positive associations were observed between cell numbers derived by the Elispot and the tetramer assay (r = 0.90). An even stronger association between tetramer-derived numbers and intracellular cytokine staining for IFN-gamma was present (r = 0.97). The majority (median 76%) of tetramer-binding cells were consistently detectable via intracellular IFN-gamma cytokine staining. Furthermore, modifications to the LDA, using a low input cell number into each well, enabled LDAs to reach equivalence with the other methods of CTL enumeration. These data together show that functionally inert CTLs do not play a significant role in chronic pediatric or adult HIV infection.

Acute otitis media in the era of effective pneumococcal conjugate vaccine: will new pathogens emerge?

The immunogenicity of pneumococcal conjugate vaccine (PCV) in young infants and its serotype-specific efficacy in otitis media (OM) results in a modest reduction in total episodes of OM and a more substantial reduction in disease due to the most frequent pneumococcal serotypes. Since PCV will only prevent disease due to the most common serotypes, concerns about potential changes in the microbiology of OM have emerged. Insight into potential changes can be obtained from reviewing middle ear and nasopharyngeal isolates from studies of antimicrobial prophylaxis and bacterial polysaccharide immune globulin for prevention of OM and PCV for prevention of invasive pneumococcal disease, respectively. In children receiving PCV, a shift in serotypes of SP colonizing the nasopharynx has been observed. Since non-vaccine serotypes are already present in the community as the etiology of acute purulent OM, it is predictable that these non-vaccine serotypes will become more common especially in children less than two years of age.

Variability of outer membrane protein P1 and its evaluation as a vaccine candidate against experimental otitis media due to nontypeable Haemophilus influenzae: an unambiguous, multifaceted approach

Candidate vaccine antigens for preventing otitis media caused by nontypeable Haemophilus influenzae (NTHI) should possess one or more conserved epitopes. We sought to evaluate the candidacy of P1, a surface-expressed outer membrane protein knowing that this antigen is subject to diversifying selection. Therefore, we selected NTHI strains from among >500 phylogenically variant isolates representative of the diversity found in natural populations of H. influenzae. Twenty-three variants of P1 (</=95% similarity) were identified among 42 strains. When chinchillas were immunized with recombinant P1 (rP1) obtained from one of these isolates (BCH-3), all animals developed antibodies specific for rP1. Immunized animals were protected against disease when challenged with BCH-3, but not with an ompP1 mutant of BCH-3 or a strain (BCH-2) possessing a heterologous P1 (91% identity). We conclude that (i) while P1 induces protection against NTHI-mediated otitis media, development of a polyvalent vaccine reflecting the variability of P1 would be necessary to construct an efficacious vaccine and (ii) use of a phylogenically characterized collection of representative isolates in concert with gene sequencing, cloning, gene inactivation, and animal testing offers an efficient, rational, and rigorous strategy for evaluating the potential problems associated with variability of vaccine targets and specificity of related immune responses.

HLA-B57-restricted cytotoxic T-lymphocyte activity in a single infected subject toward two optimal epitopes, one of which is entirely contained within the other

Viral peptides are recognized by cytotoxic T lymphocytes (CTL) as a complex with major histocompatibility complex (MHC) class I molecules, but the extent to which a single HLA allele can accommodate epitope peptides of different length and sequence is not well characterized. Here we report the identification of clonal CTL responses from the same donor that independently recognize one of two HLA-B57-restricted epitopes, KAFSPEVIPMF (KF11; p24(Gag) residues 30 to 40) and KAFSPEVI (KF8; p24(Gag) residues 30 to 37). Although lysis studies indicated that the KF11 peptide stabilized the HLA-B57-peptide complex more efficiently than the KI8 peptide, strong clonal responses were directed at each epitope. In samples from a second donor, the same phenomenon was observed, in which distinct CTL clones recognized peptide epitopes presented by the same HLA class I allele (in this case, HLA-A3) which were entirely overlapping. These data are relevant to the accurate characterization of CTL responses, which is fundamental to a detailed understanding of MHC class I-restricted immunity. In addition, these studies demonstrate marked differences in the length of peptides presented by HLA-B57, an allele which is associated with nonprogressive human immunodeficiency virus infection.

Differential narrow focusing of immunodominant human immunodeficiency virus gag-specific cytotoxic T-lymphocyte responses in infected African and caucasoid adults and children

Cytotoxic T-lymphocyte (CTL) activity plays a central role in control of viral replication and in determining outcome in cases of human immunodeficiency virus type 1 (HIV-1) infection. Incorporation of important CTL epitope sequences into candidate vaccines is, therefore, vital. Most CTL studies have focused upon small numbers of adult Caucasoid subjects infected with clade-B virus, whereas the global epidemic is most severe in sub-Saharan African populations and predominantly involves clade-C infection in both adults and children. In this study, sensitive enzyme-linked immunospot (elispot) assays have been utilized to identify the dominant Gag-specific CTL epitopes targeted by adults and children infected with clade-B or -C virus. Cohorts evaluated included 44 B-clade-infected Caucasoid American and African American adults and children and 37 C-clade-infected African adults and children from Durban, South Africa. The results show that 3 out of 46 peptides spanning p17(Gag) and p24(Gag) sequences tested contain two-thirds of the dominant Gag-specific epitopes, irrespective of the clade, ethnicity, or age group studied. However, there were distinctive differences between the dominant responses made by Caucasoids and Africans. Dominant responses in Caucasoids were more often within p17(Gag) peptide residues 16 to 30 (38 versus 12%; P < 0.01), while p24(Gag) peptide residues 41 to 60 contained the dominant Gag epitope more often in the African subjects tested (39 versus 4%; P < 0.005). Within this 20-mer p24(Gag), an epitope presented by both B42 and B81 is defined which represents the dominant Gag response in >30% of the total infected population in Durban. This epitope is closely homologous with dominant HIV-2 and simian immunodeficiency virus Gag-specific CTL epitopes. The fine focusing of dominant CTL responses to these few regions of high immunogenicity is of significance to vaccine design.

Efficacy of linezolid in experimental otitis media

Therapy for otitis media (OM) due to resistant Streptococcus pneumoniae (MIC of penicillin, >/=2.0 microgram/ml) is challenging. Linezolid, an oxazolidinone, represent a new class of antimicrobial agents with excellent in vitro activity against penicillin-resistant S. pneumoniae; however, in vitro activity against nontypeable Haemophilus influenzae (NTHI) is limited. We evaluated its efficacy against experimental acute OM due to a multidrug-resistant S. pneumoniae isolate and two isolates of NTHI. The chinchilla model was utilized to evaluate the efficacy of linezolid against experimental infection due to S. pneumoniae or NTHI. Serum and middle ear antibiotic concentrations were determined, and sterilization of experimental OM was evaluated. Chinchillas were inoculated directly with S. pneumoniae into the superior bulla. Twenty-four hours after inoculation, all animals had positive middle ear and nasopharyngeal cultures. Animals were given linezolid at 25 mg/kg/dose twice a day (b.i.d.) by orogastric feeding tube or amoxicillin at 40 mg/kg/dose b.i.d. intramuscularly for 5 days. By day 5, all animals in the linezolid group had sterile middle ear cultures and eradication of S. pneumoniae from the nasopharynx. In the amoxicillin group, all nine animals remained middle ear and nasopharynx positive (P < 0.01). In animals inoculated with NTHI, 25 and 37.5 mg/kg b.i.d. failed to sterilize middle ear infection or eradicate colonization. Mean levels in middle ear fluid measured during experimental infection were 12.8 microgram/ml at 2 to 6 h and 4. 1 mirogram/ml at 16 to 17 h after orogastric dosing at 25 mg/kg. Linezolid achieved a high concentration in the middle ear during experimental OM. Linezolid eradicated multidrug-resistant S. pneumoniae from the middle ear and nasopharynx. Experimental infection and nasopharyngeal colonization due to NTHI persisted despite achievement of concentrations in the middle ear that were above the MIC (for NTHI).

Immune response to pneumococcal conjugate and polysaccharide vaccines in otitis-prone and otitis-free children

We compared responses to pneumococcal conjugate and polysaccharide vaccines in 48 otitis-free and 64 otitis-prone children. Pre- and postimmunization concentrations of antibodies to pneumococcal serotypes 6B, 14, 19F, and 23F were measured by enzyme-linked immunosorbent assay. Postimmunization mean concentrations of antibodies to all four serotypes were significantly higher for children receiving conjugate vaccine than for those receiving polysaccharide vaccine; the difference in responses was primarily due to a better response to conjugate vaccine in the otitis-prone group. Significantly higher postimmunization concentrations of antibodies to all four serotypes and to one of the four serotypes were found in otitis-prone children and otitis-free children who received conjugate vaccine, respectively. Pneumococcal conjugate vaccine has the potential to reduce the incidence of disease due to vaccine serotypes, even among children with recurrent otitis media.

Randomised trial of intradermal Mycobacterium vaccae or intradermal hepatitis B immunisation in children with HIV infection

This study assessed the safety of inactivated Mycobacterium vaccae as a candidate vaccine to prevent disseminated mycobacterial disease in children with HIV infection. 35 children ages 1-8 with CD4 counts > or =300/mm3 in New Hampshire, Boston and Chicago were randomised in a 2:1 schedule to receive a 3-dose series of intradermal M. vaccae vaccine (MV) or hepatitis B vaccine (HBV) at 2-month intervals. Immunisation was safe and well tolerated; 2-day median vaccine site in duration was 5 mm in MV recipients and 0 mm in HBV recipients (p < 0.001). There were no significantly different changes in viral load or CD4 count between the two vaccine groups. No PPD skin test conversions occurred after immunisation. MV is safe and well tolerated and deserves further evaluation as a vaccine to prevent mycobacterial disease in HIV-infected children.

Parents, physicians, and antibiotic use

BACKGROUND

Emergence of resistant bacterial pathogens has increased concerns about antibiotic prescribing patterns. Parent expectations and pressure may influence these patterns.

OBJECTIVE

To understand how parents influence the prescribing patterns of physicians and what strategies physicians believe are important if we are going to reduce inappropriate use of oral antimicrobial agents.

DESIGNS AND METHODS

One thousand pediatricians who are members of the American Academy of Pediatrics were asked to complete a semi-structured questionnaire. The physicians were chosen randomly by the American Academy of Pediatrics.

RESULTS

Nine hundred fifteen pediatricians were eligible and 610 surveys were analyzable, for a response rate of 67%. The majority of respondents were male (56%), worked in a group practice (51%), saw an average of 114 patients per week and were in practice for 14 years. Forty percent of the pediatricians indicated that 10 or more times in the past month a parent had requested an antibiotic when the physician did not feel it was indicated. Forty-eight percent reported that parents always, most of the time, or often pressure them to prescribe antibiotics when their children are ill but antibiotics are not indicated. In follow-up questions, approximately one-third of physicians reported they occasionally or more frequently comply with these requests. Seventy-eight percent felt that educating parents would be the single most important program for reducing inappropriate oral antibiotic use and 54% indicated that parental pressure, in contrast to concerns about legal liability (12%) or need to be efficient in practice (19%), contributed most to inappropriate use of oral antibiotics.

CONCLUSIONS

Pediatricians acknowledge prescribing antimicrobial agents when they are not indicated. Pediatricians believe educating parents is necessary to promote the judicious use of antimicrobial agents.

The immunogenicity of Haemophilus influenzae type b conjugate vaccines in children born to human immunodeficiency virus-infected women. Women and Infants Transmission Study Group

BACKGROUND

Immunocompromise caused by HIV-1 infection increases the importance of receipt of routine childhood vaccines to prevent infections such as invasive Haemophilus influenzae type B (Hib) disease. The objectives of the study were to evaluate the immunogenicity of Hib conjugate vaccines among HIV-infected children according to clinical and immunologic disease progression as well as viral load.

METHODS

The concentration of antibody to polyribosylribitol phosphate (PRP) was measured at approximately 9 and 24 months of age in plasma specimens from children of HIV-infected women enrolled in the Women and Infants Transmission Study.

RESULTS

Among 227 children (35 HIV-infected, 192 uninfected) at the 9-month study visit who were known to have received age-appropriate immunization with CRM197 mutant Corynebacterium diphtheriae protein-conjugated Hib vaccine, geometric mean antibody concentrations were lower among HIV-infected children (1.64 microg/ml) than among uninfected children (2.70 microg/ml), although the difference was not statistically significant. Anti-PRP antibody concentrations did not vary significantly among these HIV-infected children with predominantly mild-moderate disease progression according to clinical category, immunologic stage or viral load (P > or = 0.48). The proportion of children with antibody concentrations > or = 1.0 microg/ml did not vary significantly according to HIV infection status (73% uninfected, 74% infected) or, if infected, clinical or immunologic disease progression or viral load. Similar results were obtained among 127 children (17 HIV-infected, 110 uninfected) eligible for analysis at the 24-month study visit. Changes in antibody concentrations over time (between 9 and 24 months of age) did not differ significantly among 10 HIV-infected as compared with 72 uninfected children (P=0.81).

CONCLUSIONS

These results suggest that HIV-infected children with predominantly mild-moderate disease progression respond reasonably well in terms of a quantitative antibody response to Hib conjugate vaccines during the first 2 years of life. Research to further characterize the immune response to Hib conjugate vaccines and to further delineate the "durability" of anti-PRP antibody concentrations beyond 2 years of life should be pursued.

Defining resistance: breakpoints and beyond implications for pediatric respiratory infection

The emergence of isolates of Streptococcus pneumoniae with reduced susceptibility to penicillins, cephalosporins, trimethoprim-sulfamethoxazole, and macrolide antibiotics requires a re-evaluation of strategies for the treatment of community-acquired respiratory disease. One response has been the consideration of withholding initial antimicrobial therapy for children with acute otitis media (AOM). Review of clinical studies supports a reduction in suppurative complications, and a more rapid resolution of signs and symptoms as well as the course of middle ear disease in children treated with antimicrobial agents. Breakpoints established by the NCCLS for in vitro susceptibility reporting may not reflect clinical efficacy at all sites of disease. Clinical studies of AOM due to penicillin-resistant S. pneumoniae report success with both cefuroxime and amoxicillin-clavulanic acid, however, microbiologic studies suggest an increase in persistent infection in children with disease due to isolates with reduced susceptibility. Successful therapy for AOM due to highly resistant isolates (MIC > or = 2.0 micrograms/ml for penicillin) has been reported with clindamycin, ceftriaxone, and high-dose amoxicillin. The current risk of AOM due to a resistant S. pneumoniae remains low in most U.S. communities. Amoxicillin remains appropriate for most children, ongoing surveillance for resistance and close monitoring of response to therapy is necessary.

New concepts in the pathophysiology and management of middle ear disease in childhood

Middle ear disease encompasses acute otitis media, recurrent otitis media, and otitis media with effusion. For many children, middle ear disease occurs early in life, is chronic and recurrent and can impair language development and/or school performance. Risk factors for recurrent otitis media include early disease onset, bottle feeding, daycare attendance, exposure to cigarette smoke and immunological defects or immaturity. Antimicrobial therapy in acute otitis media is associated with earlier resolution and a reduction in the frequency of persistent disease and suppurative complications. An antimicrobial agent should be selected according to its activity, tolerability and concentrations achieved in the middle ear. At present, amoxicillin remains the drug of choice for acute otitis media. Antimicrobial prophylaxis is also effective, but only for the duration of therapy. Future challenges for the management of middle ear disease include the treatment of penicillin-resistant Streptococcus pneumoniae, effective prevention of relapses, and the development of a vaccine for S. pneumoniae that has the appropriate serotypes and is immunogenic in young children.

Career choice in one general pediatric Title VII--supported residency

The concern that there are too few generalist physicians and too many specialists is part of the ongoing health care debate. Medical educators have been challenged at the graduate and undergraduate levels to educate more generalists. While some question the actual effect of medical education on the choice of a generalist career, others strongly express the view that a generalist curriculum influences graduates to pursue a career in primary care. Residency training programs are largely based in hospitals, and pediatric practice is largely community based. The terms educational malpractice, educational mismatch, and, most recently, educational dysjunction have been used to describe the difference between the educational and practice experience.

Early neurodevelopmental growth in children with vertically transmitted human immunodeficiency virus infection

OBJECTIVE

To examine mental and motor development in children with vertically transmitted human immunodeficiency virus (HIV) infection in the first 30 months of life.

DESIGN

Prospective longitudinal study comparing two groups: children with HIV infection and HIV-exposed but uninfected children.

SETTING

Pediatric Immunodeficiency Clinic at Boston (Mass) City Hospital, Boston University Medical Center.

STUDY PARTICIPANTS

Twenty-four children with vertically transmitted HIV infection and 27 children who were born to HIV-infected mothers and became HIV negative served as controls. Socioeconomic status, gestational age, and prenatal drug exposure were comparable in the two groups.

MEASUREMENTS/RESULTS

Using the Bayley Scales of Infant Development, all children were assessed at least once between 4 and 16 months and again between 17 and 30 months of age. Individual mean mental and motor scores were calculated for the early and later age span. Motor development in the infected group was delayed in comparison to the seroreverter group in both age spans and remained stable in both groups over time. Mental development was comparable in the two groups at 4 to 17 months, but HIV infection was associated with delay in mental development at 17 to 30 months of age.

CONCLUSION

Early and persistent delay in motor development and deceleration in mental development in late infancy distinguishes many children who are HIV infected from exposed but uninfected children, but there is significant variability in early neurodevelopmental outcome among children with HIV infection.

Seroreversion in human immunodeficiency virus-exposed but uninfected infants

The goal of this study was to describe seroreversion (SR) in a cohort of human immunodeficiency virus-exposed but uninfected infants. Groups of patients who seroreverted very early or late were examined for salient clinical and immunologic characteristics of the mother or infant. The mean time (+/- s.d.) to seroreversion by enzyme-linked immunoabsorbent assay (ELISA) was 50.1 +/- 14.8 weeks, or 11.6 months (n = 84); the range of times to antibody loss by ELISA was 17.9 to 82.0 weeks. The mean time to seroreversion by Western blot was 68.3 +/- 12.6 weeks, or 15.8 months (n = 51), with a range of 44.9 to 94.1 weeks. Initial anti-human immunodeficiency virus titer as measured by cord blood ELISA optical density (OD) was found to relate significantly to mean time to seroreversion. No relationship to time to seroreversion was demonstrated for gestational age, maternal or neonatal serum immunoglobulin concentrations, maternal CD4 cell counts, maternal alcohol consumption, infantile diarrhea or failure to thrive. The lengthy time to seroreversion seen here demonstrates the 1994 revised Centers for Disease Control and Prevention definition of human immunodeficiency virus infection (based on seropositivity by both ELISA and confirmatory tests persisting beyond 18 months of age) to be accurate in our population. We recommend Western blot testing be used as confirmation for positive ELISAs only after 18 months of age.

The incidence of prenatal syphilis at the Boston City Hospital: a comparison across four decades

OBJECTIVE

To examine the incidence and epidemiologic correlates of congenital syphilis at an inner-city Boston hospital, and draw comparisons with the situation at the same hospital 40 years ago.

DESIGN

Chart review and comparison with data collected in 1951.

SETTING

Maternity and pediatric services at Boston City Hospital.

METHODS

A study conducted in 1951 on the maternity service of Boston City Hospital in which demographic data were collected on all women admitted in labor over a 5-month period was replicated. Serologic testing for syphilis was carried out on these women, and the demographic and medical correlates of positive maternal syphilis serology were examined. This study was repeated exactly 40 years later, using the cord blood screening for syphilis done routinely at delivery and a review of prenatal records.

RESULTS

From a group made up largely of married white women in 1951, the study population shifted in 1991 to a group made up mostly of minority women, with 75% unmarried. In 1951, 24 patients were diagnosed with syphilis either before or during the pregnancy, giving a prevalence rate of 2.4%. In 1991, 25 of 647 women were diagnosed with syphilis, for a prevalence rate of 3.9%. The women with positive cord blood serologies had a higher rate of other sexually transmitted diseases and substance abuse. No symptomatic cases of congenital syphilis were seen in 1951 or in 1991, although at least 11 of the 26 infants born to mothers with positive serologies in 1991 received intravenous penicillin therapy.

CONCLUSIONS

The continued prevalence of diagnosed syphilis in women at delivery reflects an inner-city epidemic of congenital syphilis that is tied to substance abuse, human immunodeficiency virus, and changing social patterns, as well to older problems of serologic screening, prenatal care, treatment failures, and maternal reinfection. It is essential that screening programs be maintained and improved in this high-risk population, and that infants born to mothers with positive serologies receive full and adequate treatment if there is any doubt at all about their infection status.

Antibody response to measles and rubella vaccine by children with HIV infection

To determine the immunogenicity of the measles and rubella components of the measles, mumps, and rubella virus (MMR) vaccine in human immunodeficiency virus (HIV)-infected children, we compared their response to that of uninfected controls. Sera were collected from HIV-infected patients and HIV seroreverters followed in our clinic and tested as close to 2 months post-MMR vaccination as possible. Specific IgG to both rubella and measles were measured by enzyme-linked immunosorbent assay. Of 20 children with HIV, 11 responded with adequate levels of antibody to measles. In the seroreverters, 12 of 13 responded. Of the measles responders, the median antibody level was significantly lower in the HIV-infected group than in the seroreverter group. In addition, HIV-infected responders tested at 9-15 months after vaccination demonstrated a significant decline in measles antibody levels. Although there was not a difference between the two cohorts in the proportion of patients who responded to the rubella component of the vaccine, there was a significant difference in the median antibody level of the responders of the two groups. We did not find a statistical difference in CD4 counts between responders and nonresponders. Alternate strategies will need to be established to prevent measles in HIV-infected children.

Otitis media in children born to human immunodeficiency virus-infected mothers

Acute otitis media (AOM) is thought to occur frequently in children infected with human immunodeficiency virus (HIV). We compared experience with AOM of 28 HIV-infected children with that of 33 children who seroreverted to HIV antibody negative status by age 18 months. The mean number of episodes/year of AOM for children who seroreverted decreased from 1.33 in the first year of life to 0.13 in the third year, whereas the mean number of episodes/year in HIV-infected children increased from 1.89 to 2.40. By age 3 years, all HIV-infected children had experienced 1 or more episodes of AOM, and 80% had experienced 6 or more, whereas 75% of children who seroreverted had experienced 1 or more episodes, and none had had 6 or more. HIV-infected children with normal T4 lymphocyte counts had a mean of 1.18 episodes of AOM in the first year of life compared with 2.35 episodes in HIV-infected children with decreased counts (P = 0.023). HIV-infected children with low counts had a nearly 3-fold increased risk of recurrent AOM (47% vs. 18%).

Early diagnosis of HIV infection in infants by detection of IgA HIV antibodies

With the aim of achieving earlier diagnosis of human, immunodeficiency virus (HIV) infection in infants, IgA and IgM HIV antibodies in serum samples from babies born to seropositive mothers were assayed by immunoblot and enzyme-linked immunosorbent assay after removal of IgG with recombinant protein G. 64 samples were from 38 HIV-infected babies with Centers for Disease Control classifications of P1 or P2. Among these infected children IgA HIV antibodies were present in all 23 samples from those older than 12 months, in 12 of 18 samples from babies aged 6-12 months, in 5 of 10 samples from babies aged 3-5 months, and in 2 of 13 from babies under 3 months old. The 6 IgA-negative samples from infants over 6 months were all from infants with severe AIDS and/or hypogammaglobulinaemia. IgA HIV antibodies were present in twice as many samples as IgM HIV antibodies (66% vs 33%). No IgM or IgA HIV antibodies were detected in infants who subsequently seroreverted or in infants born to seronegative mothers. The correlation of the serological results with clinical information on each child suggests that detection of IgA HIV antibodies is an effective method for early diagnosis of HIV-infected infants without signs of infection.

Acquired immunodeficiency syndrome: a new population of children at risk

Cases of AIDS in children have been described since 1982. Diagnosis is more complex in children than in adults owing to the more varied clinical presentations and the difficulty in interpretation of laboratory tests. Our current understanding of HIV infection in children is reviewed, as well as the controversies regarding medical, psychosocial, and public health issues.

The draining ear. Otitis media and externa

Otorrhea, or discharge from the ear, may be associated with otitis media or otitis externa. Each episode of otorrhea requires examination of the external ear canal and middle ear to determine the origin and extent of disease, a complete understanding of the pathogenesis, and a therapeutic approach that considers the microbiology and the extent of tissue invasion. This review focuses on infections of the middle ear and external ear commonly associated with otorrhea. The pathogenesis, clinical manifestations, methods of diagnosis, and medical and surgical therapies are presented.

Characterization of antigens from nontypable Haemophilus influenzae recognized by human bactericidal antibodies. Role of Haemophilus outer membrane proteins

Major outer membrane antigens, proteins, and lipopolysaccharides (LPSs), from nontypable Haemophilus influenzae were characterized and examined as targets for complement-dependent human bactericidal antibodies. Outer membranes from two nontypable H. influenzae isolates that caused otitis media and pneumonia (middle ear and transtracheal aspirates) were prepared by shearing organisms in EDTA. These membranes were compared with membranes prepared independently by spheroplasting and lysozyme treatment of whole cells and found to have: similar sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) patterns of the proteins; identical densities (rho = 1.22 g/cm3); and minimal d-lactose dehydrogenase activity indicating purity from cytoplasmic membranes. Outer membranes were solubilized in an LPS-disaggregating buffer and proteins were separated from LPS by molecular sieve chromatography. The SDS-PAGE patterns of outer membrane proteins (OMPs) from the two strains differed in the major band although other prominent bands appeared similar in molecular weight. LPS prepared by hot phenol water extraction of each of the strains contained 45% (pneumonia isolate) and 60% (otitis isolate) lipid (wt/wt), 49% and 50% carbohydrate (wt/wt), respectively, and less than 1%, 3-deoxy-manno octulosonic acid. Immunoglobulin M (IgM) purified from normal human serum (NHS) plus complement was bactericidal for both strains. Purified immunoglobulin G (IgG) from NHS killed the middle ear isolate and immune convalescent IgM from the serum of the patient with pneumonia killed his isolate. NHS or convalescent serum were absorbed with OMPs and LPS (0.6-110 micrograms) from each of the strains and immune specific inhibition of bactericidal antibody activity by each antigen was determined. OMPs from the pulmonary isolate inhibited bactericidal antibody activity directed against the isolate in both NHS (1.5 microgram of antigen) and immune serum (0.75 microgram of antigen). OMPs (60 micrograms) from the ear isolate also inhibited bactericidal activity in the respective immune serum. LPSs exhibited minimal inhibition (greater than 110 micrograms). Three human sera (two normal, one immune) were selectively depleted of 80% of antibody activity against OMPs (measured by enzyme-linked immunosorbent assay) by affinity chromatography using OMPs from the pulmonary isolate coupled to a solid phase. These OMP antibody-depleted sera also showed an 88% reduction of bactericidal activity against this strain. Immunopurified antibody against OMPs eluted from the solid phase was bactericidal.

Modification of otitis media in chinchillas rechallenged with nontypable Haemophilus influenzae and serological response to outer membrane antigens

Otitis media was produced in chinchillas by right-sided intrabullar inoculation with nontypable Haemophilus influenzae, and susceptibility to reinfection was investigated. After resolution of initial right-sided infection, animals underwent ipsilateral or contralateral intrabullar rechallenge with the same strain. After ipsilateral rechallenge right ears were completely protected against reinfection; previously uninfected left ears were similarly protected on contralateral rechallenge. Previously infected ears remained fully susceptible to infection with a heterologous strain of nontypable H. influenzae. Using an enzyme-linked immunosorbent assay, we measured the serological response to outer membrane protein and lipopolysaccharide antigens during initial infection. A greater than or equal to 10-fold rise in titer of antibody to homologous outer membrane proteins was observed in all 11 animals tested. Most animals exhibited a minimal serological response to lipopolysaccharide. Thus experimental otitis media due to nontypable H. influenzae induces strain-specific protective immunity and a concomitant serological response to outer membrane proteins.

Do children with recurrent Haemophilus influenzae otitis media become infected with a new organism or reacquire the original strain?

Using the techniques of outer membrane protein gel analysis and biotyping, we characterized nontypable Haemophilus influenzae isolates from middle ear aspirates of 30 children with recurrent nontypable H, influenzae (NTHI) otitis media. Nine of the 13 children with early recurrence of NTHI otitis (less than 30-day intervals) had respective first and second isolates that were identical. In contrast, 14 of 18 children with late recurrences of NTHI otitis (greater than 30-day intervals) had respective first and second isolates that were different, whereas four children had late recurrences with organisms that appeared to be identical with their respective initial infecting strains. These results suggest that early recurrent NTHI otitis usually is a result of relapse with the initial infecting NTHI strain. In contrast, late recurrent disease is usually the result of infection with a new organism. However, the observation that four children had late recurrences with the original strains suggests that strain-specific protective immunity may not uniformly develop after recovery from NTHI otitis.

Bacteriology of acute otitis media unresponsive to initial antimicrobial therapy

To determine the microbiology of acute otitis media unresponsive to initial antimicrobial therapy, we performed tympanocentesis on 43 children. All had failed to improve after at least 36 hours of therapy. Initial therapy was ampicillin or amoxicillin (31), trimethoprim-sulfamethoxazole (5), erythromycin and sulfisoxazole (5), erythromycin (1), and ampicillin and gentamicin (1). Among these children, 19% had isolates from middle ear fluid resistant to initial therapy. Bacteria sensitive to initial therapy were isolated from ten children (24%). The majority of children (57%) had bacteriologically negative middle ear fluid. Resistant isolates from children initially treated with ampicillin or amoxicillin were sensitive to trimethoprim-sulfamethoxazole or to erythromycin and sulfisoxazole, and vice versa. Critically ill children should have tympanocentesis to guide therapy; other children who fail to respond to antimicrobial therapy may receive alternative therapy as indicated by the results of this study.

Disparate cultures of middle ear fluids. Results from children with bilateral otitis media

Cultures of middle ear fluids (MEFs) are needed to determine both efficacy of antibiotics and vaccines, and microbiologic outcome of otitis media (OM). We reviewed data on 221 children, aged 2 months to 12 years; 122 had acute otitis media (AOM), 99 had asymptomatic MEF. We included only Streptococcus pneumoniae, Haemophilus influenzae, Branhamella catarrhalis, and Staphylococcus aureus as pathogens. Of children with AOM, MEF was sterile or contained nonpathogens in both ears in 51, and one or more pathogens in 71. Of these 71, 40 had the same pathogen or pathogens in both ears; 25 patients had a pathogen in one ear and sterile fluid or only nonpathogens in the other; four patients had a different pathogen in each ear; and two patients had two pathogens in one ear and only one in the other. Of those with asymptomatic MEFs, in 80 the effusion was sterile or contained only nonpathogens in both ears, and in 19 contained one or more pathogens. Of these 19, ten had the same pathogen isolated from both ears; nine had a pathogen in one ear and sterile fluid or only nonpathogens in the other. Thus, in 31 children with AOM and nine with asymptomatic MEFs, results of cultures of MEF were different.

Bactericidal antibody and susceptibility to otitis media caused by nontypable strains of Haemophilus influenzae

We have developed a bactericidal antibody assay to determine the role of circulating antibody to nontypable strains of Haemophilus influenzae in children with otitis media. Antibody infecting strain was present in the acute sera of 2/20 children with otitis media caused by H. influenzae NT; 15/18 of these patients had covalescent specimens with titers greater than or equal to 1:2 (X2 = 13.0, P < 0.001). The acute sera of 95 children with otitis media caused by various organisms were screened for bactericidal activity against a randomly selected H. influenzae NT stain. Antibody was present in 0/28 acute sera of patients whose infection was caused by H. influenzae NT and in 18/67 (26.9% of those whose middleear exudates were sterile or contained other bacterial species (X2 = 9.95, P < 0.01). A bactericidal antibody response generally follows infection of the middlw ear with H. influenzae NT. The absence of antibody to a single strain in the sera of some children appears to be associated with susceptibility to this infection.