Addition of a macrolide to a ss-lactam in bacteremic pneumococcal pneumonia.

In the study presented here, data collected prospectively from 340 adult patients hospitalised in five countries with bacteremic pneumococcal CAP and treated with a ss-lactam +/- a macrolide were analysed retrospectively to evaluate the efficacy of this antimicrobial combination. Univariate and multivariate analyses revealed no significant effect on case fatality rate when a macrolide/ss-lactam regimen was used as initial therapy. Results were not affected by severity of illness, or by excluding patients who died within 2 days of admission. Identified predictors of death in a multivariate regression model were age >65 years (OR=2.6), two or more lung lobes affected (OR=2.2), and severity of disease as estimated using the acute physiology score (APS)>8.

Surveillance of penicillin-resistant Streptococcus pneumoniae in one American metropolitan area, 1989-1998.

The emergence of invasive penicillin-resistant (PRSP) and multidrug-resistant (MDRP) Streptococcus pneumoniae was tracked from 1989 to 1998 in one medium-sized metropolitan area in the USA, encompassing western West Virginia, including Huntington, the only major city, and neighboring sections of Kentucky and Ohio. Capsular serotyping and antibiotic sensitivity tests were performed on 350 community-acquired isolates comprising 93.1% of all pneumococcal isolates identified. The incidence of PRSP increased from 3 to 10% during the 10 years of the study. Twenty-nine (22.1%) of 131 isolates of serotypes 6, 9, 14, 19, and 23 were PRSP (one-fourth were MDRP) and 1 (0.5%) of 219 other serotypes was PRSP (serotype 35). Invasive PRSP occurred most frequently in young children and in adults aged 80 years and older, 8.9 and 10.9 cases per 100,000 persons, respectively.

Molecular epidemiology of Streptococcus pneumoniae causing invasive disease in 5 countries.

A multicenter study was done during 1993-1995 to investigate prospectively the influence of several prognostic factors for predicting the risk of death among patients with pneumococcal bacteremia. Five centers located in Canada, the United Kingdom, Spain, Sweden, and the United States participated. Clinical parameters were correlated to antibiotic susceptibility and serotyping of the 354 invasive pneumococcal isolates collected and to molecular typing of 173 isolates belonging to the 5 most common serotypes (14, 9V, 23F, 3, and 7F). Serotype 14 was the most common among all isolates, but serotype 3 dominated in fatal cases and in isolates from Spain and the United States, the countries with the highest case-fatality rates. Fewer different patterns were found among the type 3 isolates, which suggests a closer clonal relationship than that among isolates belonging to other serotypes. Of type 3 isolates from fatal cases, 1 clone predominated. Other penicillin-susceptible invasive clones were also shown to spread in and between countries.

Prospective study of prognostic factors in community-acquired bacteremic pneumococcal disease in 5 countries.

To define the influence of prognostic factors in patients with community-acquired pneumococcal bacteremia, a 2-year prospective study was performed in 5 centers in Canada, the United States, the United Kingdom, Spain, and Sweden. By multivariate analysis, the independent predictors of death among the 460 patients were age >65 years (odds ratio [OR], 2.2), living in a nursing home (OR, 2.8), presence of chronic pulmonary disease (OR, 2.5), high acute physiology score (OR for scores 9-14, 7.6; for scores 15-17, 22; and for scores >17, 41), and need for mechanical ventilation (OR, 4.4). Of patients with meningitis, 26% died. Of patients with pneumonia without meningitis, 19% of those with >/=2 lobes and 7% of those with only 1 lobe involved (P=.0016) died. The case-fatality rate differed significantly among the centers: 20% in the United States and Spain, 13% in the United Kingdom, 8% in Sweden, and 6% in Canada. Differences of disease severity and of frequencies and impact of underlying chronic conditions were factors of probable importance for different outcomes.

Antibody response of pneumococcal vaccine: need for booster dosing?

The approved pneumococcal vaccine comprises purified capsular polysaccharide of 23 stereotypes that account for more than 90% of the invasive pneumococcal infections in the USA. It induces adequate anti-polysaccharide IgG antibody levels to most or all of the component polysaccharide antigens in immunocompetent adults. Elderly adults respond about equally well to vaccination as do younger adults. Pneumococcal antibody declines over time, often below 1 month post-vaccination levels, and sometimes about to pre-primary vaccination levels. Second doses of vaccine satisfactorily boost antibody levels in healthy adults, but not in immunocompromised adults or children. The rate of antibody decline differs for the differing capsular stereotypes. In time, pneumococcal antibody wanes in all healthy persons perhaps increasing their risk of serious pneumococcal disease. Elderly and high risk persons face the highest risk of death from invasive pneumococcal disease, supporting the proposition that for these groups revaccination with pneumococcal vaccine at regular intervals may provide the needed increased measure of protection.

A 20-year epidemiological study of pneumococcal meningitis.

We conducted a retrospective analysis of 55 community-acquired Streptococcus pneumoniae meningitis illnesses in Huntington, West Virginia, from 1978 to 1997. Fourteen (36.8%) of 38 adults and 2 (11.8%) of 17 children died. Serotypes 6, 23, 3, and 18 accounted for 20 (41.7%) of 48 strains available for serotyping. Of 40 strains available for antimicrobial susceptibility testing, 1 serotype 19 and 1 serotype 23 strain showed intermediate resistance and a second serotype 23 strain showed high resistance to penicillin; all three patients survived. The case-fatality rates among adults who received penicillin alone, gentamicin in combination, or vancomycin and cephalosporin together were 57.1%, 55.5%, and 60%, respectively, and among those who received chloramphenicol or a third-generation cephalosporin, they were 11.1% or nil, respectively. No child died who received chloramphenicol or vancomycin. Two (33%) of 6 children died who received a third-generation cephalosporin; both were critically ill when initially treated. No child and one adult had received pneumococcal vaccine prior to becoming ill.

Bacteremic pneumococcal pneumonia in one American City: a 20-year longitudinal study, 1978-1997.

A surveillance of bacteremic pneumococcal pneumonia was conducted in Huntington, West Virginia, from 1978 to 1997 to investigate case-fatality rates, incidence of disease, capsular types, and antibiotic usage. Our study population comprised consecutive inpatients admitted to the hospitals in Huntington, West Virginia, and included 45 children younger than 15 years and 328 adults. All blood isolates were serotyped by capsular swelling procedures; clinical characteristics, treatment, and outcome for all patients were abstracted from hospital charts. The overall case-fatality rate was 20.3%, with most deaths occurring among adults older than 50 years. Case-fatality rates peaked at 37.7% among patients 80 years of age and older. Only 1 of 45 (2.2%) children died. Case-fatality rates declined in each successive 5-year period, from 30.2% in 1978-1982 to 15.6% in 1993-1997. In that same period, incidence rates increased severalfold among children younger than 4 years to 44.5 cases per 100,000 population and among adults 70 years and 80 years of age and older to 38.5 and 76.2 cases per 100,000, respectively. Of the 34 serotypes isolated, 10 accounted for two thirds of the cases of pneumonia: 1, 4, 9, 14, 3, 6, 12, 5, 23, and 19 (in rank order). Chronic renal disease and arteriosclerotic heart disease increased the risk of death. Treatment regimens that included a macrolide and a penicillin or cephalosporin resulted in the lowest case-fatality rate in adults older than 50 years: 6% in 1993-1997. In conclusion, as bacteremic pneumococcal pneumonia evolved over time, the case-fatality rate decreased, its incidence increased, predominant capsular types changed, and treatment regimens that included a macrolide resulted in the lowest fatality rates.

Antigenic and genetic diversity among the attachment proteins of group A respiratory syncytial viruses that have caused repeat infections in children.

Antigenic differences between the two major groups of respiratory syncytial (RS) virus may contribute to reinfections with these viruses. Additional variability occurs within the two major groups; the importance of intra-group variability in reinfections with RS virus has not been defined. Two pairs of group A viruses that had caused sequential infections in children showed G protein amino acid differences of up to 15%. Vaccinia viruses were constructed that expressed the G proteins from 2 of the paired group A isolates. Immunization of cotton rats with the recombinant vaccinia viruses provided equal protection against intranasal challenge by either of the RS viruses. Despite the amino acid differences between the two group A RS virus G proteins, these animal studies did not reveal differences in protection after immunization with the two G proteins. Precise definition of the role of RS virus antigenic variability in the establishment of reinfections in humans will require further investigations in humans.

Phosphoprotein profile analysis of ruminant respiratory syncytial virus isolates.

OBJECTIVE: To determine the apparent molecular weight for 24 ruminant respiratory syncytial viruses (RSV) on the basis of differences in the electrophoretic mobility of the phosphoprotein (P protein). PROCEDURE: 29 bovine RSV (BRSV), 20 of which were not previously tested, 3 ovine RSV, and 1 caprine RSV isolates were selected for determination of electrophoretic mobility of the P protein. Virus radiolabeled with [35S]methionine was immunoprecipitated with polyclonal antiserum to BRSV and analyzed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. RESULTS: On the basis of apparent molecular size of the P protein, all isolates could be categorized into 2 electropherotypes, low molecular size of 36 kd and high molecular size of 38 kd. Twenty-three BRSV, the 3 ovine RSV, and 1 caprine RSV isolates had a high molecular size P protein; 6 BRSV isolates had a low molecular size P protein. CONCLUSIONS: The apparent molecular size of the P protein of the ruminant RSV strains is greater than that of the human RSV subgroups, providing further evidence of their distinctiveness. Whether categorization of electrophoretic mobility of the P protein of BRSV underlies distinct antigenic subgroups, as it does in human RSV, requires further antigenic and genetic analysis. CLINICAL RELEVANCE: Antigenic subgroups of ruminant RSV may have relevance in the development of new vaccines for control of the disease.

Identification of a variant subgroup A strain of respiratory syncytial virus.

During epidemiologic surveillance of children with respiratory syncytial virus (RSV) disease in Huntington, W.Va., we identified seven strains of a new variant subgroup A RSV (subgroup A-Var) by their reactions in an enzyme immunoassay with two anti-F monoclonal antibodies (MAbs) specific for two epitopes, F1 and F4, generated against the subgroup B RSV. The prototype strain of subgroup A and all other subgroup A field strains from that epidemiologic year failed to react with these two subgroup B MAbs. Additional enzyme immunoassays with 18 subgroup B anti-F MAbs specific for 14 epitopes showed that subgroup A-Var strains also reacted with a MAb specific for the subgroup B F2 epitope. In a radioimmune precipitation assay, the molecular size of the subgroup A-Var F2 subunit of the fusion (F) protein clearly differed from those of both prototype strains of subgroup A and subgroup B RSV. The molecular size of the F2 subunit of subgroup A-Var (24 kDa) was intermediate between the size of the F2 subunit of subgroup A (25 kDa) and that of subgroup B (23 kDa). However, the molecular sizes of the F1 subunits of both subgroup A and subgroup A-Var were identical (54 kDa) and slightly larger than those of the F1 subunits of both subgroups B1 and B2 (53 kDa). These data suggest that subgroup A-Var may represent a distinct RSV A subgroup, analogous to subgroup B1 and B2 RSV, and it is the first-identified naturally occurring subgroup A RSV with an F protein different from that of the prototype A RSV.

Emergence of penicillin-resistant invasive pneumococci in a single American community.

Three decades ago, penicillin-resistant strains of Streptococcus pneumoniae were first reported. Since then, myriad penicillin resistant strains of S. pneumoniae have been identified worldwide and in the United States. No resistant or intermediate resistant strains have been reported in West Virginia because testing has not been done. Between 1983 and 1994, the authors' surveillance of invasive pneumococcal disease in metropolitan Huntington, West Virginia, identified 356 pneumococcal strains from blood and other usually sterile sites, including 110 strains belonging to serotypes 6, 9, 14, 19, and 23, the main serotypes exhibiting penicillin resistance. The authors tested these serotypes for penicillin susceptibility by the E-test. Sixteen (14.5%) strains of types 6, 9, 14, 19, and 23 exhibited intermediate resistance to penicillin. No highly resistant strains were identified. Most of the intermediate resistant strains of types 9, 14, and 23 were detected in epidemiologic years 1992-1994. The increasing number of intermediate resistant penicillin strains signals the need for routine testing of invasive pneumococcal strains for penicillin susceptibility and necessitates appropriate antibiotic usage.

Evaluation of subgroup-specific peptides of the G protein of respiratory syncytial virus for characterization of the immune response.

Two synthetic peptides, designated peptides 12G(A) and 12G(B), representing amino acids 174-188 of the G glycoprotein of respiratory syncytial virus (RSV) subgroup A (strain A2) and subgroup B (strain CH18537) were evaluated for their properties as subgroup-specific antigens for enzyme immunoassay (ELISA). These peptides were used to characterize the immune response of children with naturally occurring RSV infection during six annual epidemics in the Huntington area, West Virginia, USA; viz. 1978-1979, 1979-1980, 1980-1981, 1983-1984, 1989-1990, and 1990-1991. The study group comprised 43 paired sera from 42 infants and children, who ranged in age between 1 month and 5.5 years of age (median age 16 months). The inclusion criteria were subgroup identification of RSV, respiratory tract illness requiring admission to hospital, and the availability of paired sera. Five of 30 children with subgroup A and 3 of 13 children with subgroup B infections developed homologous or dual fourfold or greater antibody responses to peptides 12G(A) and 12G(B) during convalescence; six of these eight children also developed antibody rises to whole virus antigens. Twenty children (14 subgroup A and 6 subgroup B) developed such responses in antibody only to whole virus (not to the peptides), and 15 children (11 subgroup A and 4 subgroup B) failed to develop a rise in antibody. Children who developed rises in antibody to the peptides were usually less than 9 months of age, suggesting that a response to peptides was more likely to occur during primary infection. Peptides 12G(A) and 12G(B) of RSV G protein lacked sufficient sensitivity and specificity to serve as antigens for ELISA for characterizing the subgroup-specific immune responses to RSV infection in infants and children.

Production and characterization of monoclonal antibodies to bovine respiratory syncytial virus.

Monoclonal antibodies to the SmithKline Beecham Animal Health BRSVR vaccine strain (375 isolate of Bovine Respiratory Syncytial Virus) were produced and then characterized by radioimmunoprecipitation followed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis, virus neutralization, inhibition of viral-induced fusion and isotype. Nineteen hybridomas produced antibodies that were reactive with the F0, F1, N or P viral proteins of bovine respiratory syncytial virus. One hybridoma (1E72C4) produced antibodies that immunoprecipitated the F0 glycoprotein, neutralized virus (1:8) in the presence of complement, but did not inhibit fusion. Another hybridoma (8B21E7) produced antibodies that immunoprecipitated the F0, F1 and F2 glycoproteins, neutralized virus (1:4) with and without complement and inhibited fusion. Antibodies from 11 hybridomas immunoprecipitated N and F1 proteins, one hybridoma immunoprecipitated the N and P protein, and 5 hybridomas immunoprecipitated the N protein. All monoclonal antibodies were of the IgG2b subtype with either kappa or lambda light chains.

Antibody to capsular polysaccharides of Streptococcus pneumoniae: prevalence, persistence, and response to revaccination.

The prevalence of immunity to Streptococcus pneumoniae in the adult population of the United States is unknown. In the study described herein, military recruits had anticapsular IgG antibody to only 15% of common pneumococcal serotypes, whereas working men and elderly men had IgG antibody to 33% and 34% of the common serotypes, respectively (P < .001). Among eight elderly subjects, the prevalence of IgG antibody to capsular polysaccharides increased from 30% to 78% after pneumococcal vaccination; 6 years thereafter, the rate of positive reactions had declined to 58% and IgG levels had declined substantially. With revaccination, IgG levels returned to within (+/-) 40% of the original postvaccination levels. IgM and IgG antibody appeared or began to increase in titer 6 days after vaccination; the rate and degree of response were the same after the first and second exposures. Since most individuals rapidly develop IgG antibody after colonization by S. pneumoniae and since IgG confers immunity, these data suggest that pneumonia is infrequent among healthy adults not because preexisting immunity is widespread but because--with colonization--an immune response develops rapidly, preceding specific events that might lead to infection. Our findings support recommended vaccination procedures and suggest that wider application in subsets of healthy younger adults should be considered.

Antibody responses of children to the C-terminal peptide of the SH protein of respiratory syncytial virus and the immunological characterization of this protein.

The SH protein of RSV, a small integrated hydrophobic membrane protein, consists of 64 amino acid residues in the polypeptide of subgroup A and 65 amino acid residues in the polypeptide of subgroup B. We synthesized five peptides, representing the SH protein of each RSV subgroup comprised of the following amino acid residues: 2-16, 12-26, 35-49, 45-60, and for subgroup A, 51-64 and for subgroup B, 51-65. Peptides 2-16 and 51-64/65 represented the N-terminal and C-terminal ends of the protein, respectively. In RIPA, under reducing conditions with mercaptoethanol, hyperimmune guinea pig (GP) serum against C-terminal peptide of the two subgroups precipitated the homologous 7.5 kDa and 21-30 kDa SH proteins. Under nonreducing conditions, the GP antipeptide sera precipitated all three SH proteins, suggesting that the 13-15 kDa protein exists as a dimer. The subgroup A 7.5 and 13-15 kDa proteins had apparent molecular weights about 1-2 kDa higher than the corresponding subgroup B proteins. The C-terminal peptides of subgroups A and B were used to characterize the immune response of 11 children, age 1 month to 1 year, with presumed primary RSV infection. Three of 4 children with subgroup A infection and 4 of 7 children with subgroup B infection developed homologous 4-fold rises in antibody to C-terminal peptide (aa 51-64/65) during convalescence. Except for one child with subgroup A and one child with subgroup B infection, the other 5 children developed heterologous rises also.(ABSTRACT TRUNCATED AT 250 WORDS)