Usefulness of pneumococcal antigen detection in pleural effusion for the rapid diagnosis of infection by Streptococcus pneumoniae.

Pleural effusion is increasingly reported in children. Standard culture of blood or pleural fluid is frequently negative and molecular diagnosis by polymerase chain reaction is not available in all hospitals. The Binax NOW Streptococcus pneumoniae Antigen test (Binax, Portland, USA) is a rapid immunochromatographic test (ICT) for the detection of the C polysaccharide antigen. We evaluated the Binax NOW test on the pleural fluid of 73 children hospitalized with pleural effusion over a period of 4 years. In our sample, the sensitivity and specificity of ICT were high (88% and 71%, respectively), with a positive predictive value of 96%. Detection of the pneumococcal antigen in pleural fluid by ICT is easy and quick, and enables us to identify the pneumococcal origin of the effusion, thus, making the treatment of complicated pneumonia suitably and early.

Analysis of the genetic structure of nontypeable pneumococcal strains isolated from conjunctiva.

More than 50% of the nontypeable (NT) pneumococcal strains received in our laboratory for reference purposes are isolated in sporadic cases of conjunctivitis. To determine the genetic structure of the population of these NT conjunctival strains, we analyzed 75 pneumococci (40 NT and 35 typeable) isolated from conjunctivas and 30 (15 NT and 15 typeable) isolated from other sources. The NT and typeable conjunctival strains grouped in separate clusters, whereas NT and typeable pneumococci isolated from other sources were similarly distributed. NT conjunctival strains belonged to two well-differentiated clonal lineages. The first, represented by three newly described sequence types, featured fully antibiotic susceptible strains and appeared to be characteristic of conjunctival tissue; the second, represented by the previously described ST344, had a pattern of multiresistance to penicillin, tetracycline, and erythromycin and shared a genetic background with some NT strains isolated from other sources.

Effectiveness of pneumococcal vaccination for elderly people in Catalonia, Spain: a case-control study.

BACKGROUND: Observational studies offer an approach to evaluating the effectiveness of vaccination programs. We evaluated the effectiveness of a 23-valent pneumococcal vaccination program for elderly people in Catalonia, Spain, in a matched-set case-control study. METHODS: We identified 149 cases of invasive pneumococcal disease among patients aged > or =65 years who were hospitalized in 12 large hospitals in Catalonia during the period of 1 January 2001 through 31 March 2002. We selected 2 hospital control patients and 1 outpatient control subject for each case patient, matching on the basis of age and underlying medical conditions. We obtained their pneumococcal vaccination histories and used conditional logistic regression to determine effectiveness of vaccination. RESULTS: Among all 149 cases of invasive pneumococcal disease, 131 (87.9%) were caused by vaccine or vaccine-related serotypes. In the adjusted analysis, overall effectiveness of vaccination against infections due to all serotypes was 70% (95% confidence interval [CI], 48%-82%). Among immunocompetent subjects with or without high-risk conditions, effectiveness of vaccination was 76% (95% CI, 51%-88%), but among immunocompromised subjects it was 50% (95% CI, -44% to 82%). Among subjects with infections due to vaccine or vaccine-related serotypes, effectiveness of vaccination was 72% (95% CI, 50%-85%) overall and 78% (95% CI, 50%-90%) in those who were immunocompetent, but it was only 46% (95% CI, -54% to 81%) in those who were immunocompromised. Overall effectiveness of vaccination was 65% (95% CI, 35%-81%) during the noninfluenza period. CONCLUSIONS: Pneumococcal vaccination was effective in preventing invasive pneumococcal disease among all elderly persons in Catalonia. Effectiveness was greater in immunocompetent persons, most of whom had underlying high-risk conditions. The number of subjects was too small to determine whether vaccination was effective in those who were immunocompromised.

Effect of opsonophagocytosis mediated by specific antibodies on the co-amoxiclav serum bactericidal activity against Streptococcus pneumoniae after administration of a single oral dose of pharmacokinetically enhanced 2000/125 mg co-amoxiclav to healthy volunteers.

OBJECTIVES: To measure the effect of opsonophagocytosis mediated by complement activated by specific antibodies on the co-amoxiclav serum bactericidal activity against Streptococcus pneumoniae strains with reduced susceptibility to beta-lactams (amoxicillin MICs of 2, 4, 8 and 16 mg/L). METHODS: An open Phase I study measuring ex vivo bactericidal activity after anti-pneumococcal vaccination and an oral dose of 2000/125 mg sustained-release co-amoxiclav was carried out. The ex vivo bactericidal activity was investigated through killing curves over 3 h [assuring polymorphonuclear neutrophil (PMN) viability] with serum samples collected 1.5 h and 5 h after dosing. Global killing was measured as the area under the killing curve (AUKC; log cfu x h/mL). The AUKC of the control growth curve of S. pneumoniae in Hanks' balanced salt solution (AUKC(K)) was used as control. The effect of the presence of complement and/or PMN was evaluated by the difference in the AUKC(K) and the different AUKCs obtained in the presence of inactivated serum (AUKC(IS)), active serum (AUKC(S)), inactivated serum plus PMN (AUKC(IS+PMN)) and active serum plus PMN (AUKC(S+PMN)). RESULTS: Significant differences were found in all cases between the bactericidal activity of active serum+PMN (AUKC(K) - AUKC(S+PMN)) and that of inactivated serum (AUKC(K) - AUKC(IS)) with therapeutic indexes ranging from 0.56 to 3.04. At 1.5 h after dosing, a significantly higher bactericidal activity of co-amoxiclav was obtained when opsonophagocytosis occurred (samples with active serum and PMN) than when not occurring (killing curves with inactivated serum and without PMN), for all amoxicillin non-susceptible strains. CONCLUSIONS: The results of this ex vivo study suggest that the collaboration of co-amoxiclav and complement-mediated opsonophagocytosis activated by specific antibodies may lay new approaches to overcome in vivo amoxicillin non-susceptibility.

Assessment of antibody response elicited by a 7-valent pneumococcal conjugate vaccine in pediatric human immunodeficiency virus infection.

We investigated antibody responses against pneumococci of serotypes 6B, 14, and 23F in 56 children and adolescents with perinatal human immunodeficiency virus (HIV) infection who were vaccinated with 7-valent pneumococcal conjugate vaccine. Overall immune responses differed greatly between serotypes. Correlation coefficients between immunoglobulin G (IgG) measured by enzyme-linked immunosorbent assay (ELISA) and functional antibodies measured by a flow cytometry opsonophagocytosis assay (OPA) varied with serotype and time points studied. After 3 months of administering a second PCV7 dose we got the highest correlation (with significant r values of 0.754, 0.414, and 0.593 for serotypes 6B, 14, and 23F, respectively) but no significant increase in IgG concentration and OPA titers compared to the first dose. We defined a responder to a serotype included in the vaccine with two criteria: frequency of at least twofold OPA and ELISA increases for each serotype and frequency of conversion from negative to positive OPA levels. Responders varied from 43.9% to 46.3%, 28.5% to 50.0%, and 38.0% to 50.0% for serotypes 6B, 14, and 23F, respectively, depending on the response criterion. The present research highlights the importance of demonstrating vaccine immunogenicity with suitable immunological endpoints in immunocompromised patients and also the need to define how much antibody is required for protection from different serotypes, since immunogenicity differed significantly between serotypes.

Effect of social and climatological factors on antimicrobial use and Streptococcus pneumoniae resistance in different provinces in Spain.

OBJECTIVES: To investigate the association between geographical differences in antibiotic consumption and resistance of Streptococcus pneumoniae to penicillin and erythromycin in 15 provinces of Spain, taking into account the potential influence of a series of social and climatological factors. METHODS: Possible correlations between prevalence of resistance to penicillin and erythromycin of S. pneumoniae, as determined in the national reference laboratory, and antibiotic consumption, and socio-economic and climatological variables were investigated. Partial correlations and multivariate linear regression were performed to assess the relative importance of variables predicting resistance and to investigate explicative factors for antibiotic consumption, respectively. RESULTS: A correlation was found between resistance and educational level, the proportion of young people in the population and climate, but was explained by their effects on differences in antibiotic use, which appeared to be the basic and only force behind resistance patterns in different geographical areas. Antibiotic use was found to be determined by the interplay of adult illiteracy, rainfall and GDP per capita. CONCLUSIONS: Interventions aimed at improving educational level and economic growth might therefore be followed by a noticeable reduction in overall antibiotic consumption, which might in turn be followed by a reduction in penicillin and erythromycin resistance in clinical isolates of S. pneumoniae.

Phage lytic enzymes as therapy for antibiotic-resistant Streptococcus pneumoniae infection in a murine sepsis model.

OBJECTIVES: Phage-coded lysins, i.e. murein hydrolases, are enzymes that destroy the cell wall of bacteria. A rapid killing of Streptococcus pneumoniae in the nasopharynx of mice has been described recently using a phage-coded murein hydrolase (enzybiotic). The in vivo effects of a dose-ranging treatment, using either of the phage-coded lytic enzymes Cpl-1 lysozyme or the Pal amidase, have been investigated here in a murine sepsis model. METHODS: Purified Pal amidase and/or Cpl-1 lysozyme were used alone or in combination. These enzymes were injected intraperitoneally at different times after challenge with 5 x 10(7) cfu of a type 6B, antibiotic-resistant S. pneumoniae clinical isolate. RESULTS: Animals challenged with 5 x 10(7) cfu of this strain alone died within 72 h, whereas a single intraperitoneal injection of Cpl-1 or Pal (200 microg; 1100 U) administered 1 h after the bacterial challenge was sufficient to effectively protect the mice, according to unpaired t-test (P<0.0001). Bacteraemia in unprotected mice reached colony counts >10(7) cfu/mL, whereas the mean colony count in lysin-protected animals was <10(6) cfu/mL over time and ultimately became undetectable. Interestingly, a synergic effect in vivo was observed with the combined use of 2.5 microg each of Cpl-1 and Pal. CONCLUSIONS: Our findings suggest strongly that phage lysins protect animals from bacteraemia and death. Moreover, the simultaneous attack of the pneumococcal peptidoglycan by a lysozyme and an amidase leads to a remarkable effect through enhanced destruction of the bacterial cell wall. The benefits of therapy with enzybiotics against pneumococcus reported here might warrant the examination of alternative strategies for the treatment of diseases caused by clinically relevant pathogens.

Immunity to Streptococcus pneumoniae: Factors affecting production and efficacy.

Streptococcus pneumoniae is a complex human pathogen and a major cause of morbidity and mortality. The genetic background of pneumococci and the chemical structure of their capsules is largely unraveled as well as the basic role of anticapsular antibodies and other opsonins interacting to enhance phagocytosis. Many experimental studies are improving our knowledge on the complex molecular mechanisms underlying those events. Pneumococcal optimal clearance requires the cooperation of a plethora of reactions from both innate and adaptive immunity. The last advances in the complexity of the immune response and protection are reviewed: phagocyte-pneumococcus interactions mediated by opsonins; the role of complement, reactive C protein and natural antibodies; details of novel immune evasion mechanisms; the complex role of the inflammatory mediators in the susceptibility to pneumococcal infections; why capsular polysaccharides do not yield an anamnestic response after primary immunization; the central question of whether T cells regulate in-vivo anti-polysaccharide immunoglobulin responses to intact pathogens. All of these are topics where new data and some answers are offered. The state of the art on the research of pneumococcal protein vaccines as an alternative to plain polysaccharide or conjugated vaccine and the establishment of immunologic correlates of protection to facilitate efficacy trial assessment are also reviewed.

Importance of local variations in antibiotic consumption and geographical differences of erythromycin and penicillin resistance in Streptococcus pneumoniae.

A geographical analysis of how commonly prescribed oral antibiotics are quantitatively and qualitatively responsible for the different local rates of erythromycin and penicillin resistance in Streptococcus pneumoniae in Spain is presented. From 1998 to 1999 a multicenter surveillance study yielded 1,684 consecutive S. pneumoniae isolates from community-acquired respiratory infections. Data on antibiotic sales in the retail market for the same period were gathered, and the corresponding defined doses per 1,000 inhabitants per day were calculated. Macrolides and beta-lactams were considered separately. Macrolides were subdivided into thrice-, twice-, and once-a-day macrolides, and beta-lactams were split into aminopenicillins and cephalosporins. Univariate Spearman nonparametric coefficients (R) were calculated, and variables proving to be significantly associated (P < 0.1) were entered into several multiple lineal regression models. Ample variation in both resistance rates and antibiotic consumption was seen. Multivariate analyses showed that integrated consumption of both macrolides and beta-lactams accounted well for erythromycin (R(2) = 0.722; P = 0.002) and penicillin (R(2) = 0.706; P = 0.002) resistance. Macrolides were more important drivers for local differences in both erythromycin and penicillin resistance than beta-lactams were. Consumption of once-a-day macrolides was key for local erythromycin resistance variations. Cephalosporins were slightly more important penicillin resistance drivers than aminopenicillins were.