Serotypes of Streptococcus pneumoniae blood culture isolates from adults in Franklin County, Ohio

Temporal Variations among Invasive Pneumococcal Disease Serotypes in Children and Adults in Germany (1992-2008)

Nationwide surveillance of invasive pneumococcal disease has been conducted in Germany since 1992. From 1992 to 2008, a total of 12,137 isolates from invasive pneumococcal disease were collected. Data on serotypes were available for 9,394 invasive isolates. The leading serotypes were serotypes 14 (16.5%), 3 (8.0%), 7F (7.6%), 1 (7.3%), and 23F (6.0%). Variations in serotype distribution over the years are particularly extensive, especially concerning serotype 14 (min 7.4%, max 33.5%) with the highest percentages among the isolates serotyped from around 1997 to 2006. Serotypes 1 and 7F increased over the last decade. No increase was observed concerning serotype 19A. Higher pneumococcal conjugate vaccine coverages were observed among children (7v, 57.3%; 10v, 72.8%; 13v, 83.5%) than among adults (7v, 39.9%; 10v, 55.5%; 13v, 73.5%). The temporal variations in serotype distribution have to be kept in mind when interpreting vaccine coverages reported in epidemiological studies.

Association of serotypes of Streptococcus pneumoniae with age in invasive pneumococcal disease

A total of 7,764 isolates from patients with invasive pneumococcal disease (IPD) were collected from 1992 to June 2006. Data on serotypes were available for 5,022 isolates (64.7% of all invasive isolates). Some 54.0% of the isolates originated from adults >or=16 years of age, and 46.0% were from children <16 years of age. The leading serotypes were 14, 23F, 1, 6B, 7F, 3, and 4. The serotypes significantly more common in children were 14, 6B, 19F, and 18C, while among adults, serotypes 3 and 4 were predominant. Serotype 7F was statistically more prevalent among children <4 months old than among the other age groups. Among children aged >or=4 months and <1 year, serotype 19F occurred statistically more frequently; and among children aged >or=1 year to <5 years, serotypes 14, 6B, and 18C were overrepresented. The serotypes predominantly affecting patients younger than the remaining collective of patients were 14, 6B, 19F, and 18C, while patients with IPD caused by serotypes 3, 4, and 9V were older than the collective, on average.

Impact of pneumococcal conjugate vaccine and the severity of winter influenza-like illnesses on invasive pneumococcal infections in children and adults

BACKGROUND

Pneumococcal conjugate vaccine (PCV7), recommended in July 2000 for routine use in infants, has resulted in a reduction in the rate of invasive pneumococcal disease (IPD) in young children. We studied the impact of PCV7 and the possible contribution of the severity of influenza-like respiratory infection season on the rate of IPD on children and adults.

METHODS

In 7 hospitals of a health system, episodes of IPD were identified by the microbiology laboratories during the 2-year period before July 2000 and the 4-year period after July 2000 during routine use of PCV7, and patient records were reviewed. Episodes of influenza-like illnesses during each winter in a local county were prospectively measured by reports from all acute care hospitals and episodes of absenteeism resulting from influenza-like illnesses from all schools.

RESULTS

There were 720 patients with blood and/or cerebrospinal fluid isolates of Streptococcus pneumoniae. There were significant reductions in cases of IPD in children younger than 2 years, 68% reduction; children 2-4 years of age, 70%; adults 18-49 years of age, 42%; and adults older than 64 years, 30%. Annually, during the PCV7 period, there were significantly fewer episodes of influenza-like illnesses than during the pre-PCV7 years.

CONCLUSIONS

PCV7 efficacy and resultant herd-type immunity resulted in a reduction in the rate of IPD not only in young children but also in young and elderly adults. Milder winter respiratory viral seasons may possibly have contributed to the observed reduction in the rate of IPD.

Historical changes in pneumococcal serogroup distribution: implications for the era of pneumococcal conjugate vaccines

Of the 90 pneumococcal serotypes, the 7 in the licensed pneumococcal conjugate vaccine (Prevnar) currently account for >80% of invasive pneumococcal infections among children in the United States. Our objective was to document and explain the changes in pneumococcal serogroup distribution in the United States during the last century. We evaluated temporal trends in the serogroup distribution, using linear regression. Between 1928 and 1998, the proportion of pneumococcal infections caused by the 7 serogroups in the conjugate vaccine increased significantly, from 15% to 59%, in 13 adult studies, and from 53% to 87%, in 19 pediatric studies. The proportion of infections caused by the "epidemic" serogroups (1-3 and 5) decreased significantly, from 71% to 7%, in the adult studies, and from 18% to 2%, in the studies of children. These historical trends in serogroup distribution may be explained by changes in antibiotic use, socioeconomic conditions, the immunocompromised status of populations, and blood-culturing practices.

The contribution of specific pneumococcal serogroups to different disease manifestations: implications for conjugate vaccine formulation and use, part II

To assess whether certain serogroups of Streptococcus pneumoniae are preferentially associated with specific disease manifestations, we analyzed all recent pneumococcal disease studies and assessed the relative frequency of isolation of each serogroup by clinical site (as a proxy for different disease states). In all age groups, serogroups 1 and 14 were more often isolated from blood, and serogroups 6, 10, and 23 were more often isolated from cerebrospinal fluid (CSF); in young children, serogroups 3, 19, and 23 were more often isolated from middle ear fluid (MEF). Serogroups represented in conjugate vaccines were isolated slightly less frequently from CSF than from blood or MEF. Nonetheless, serogroups in the 9-valent conjugate vaccine formulation still comprised approximately 75% of pneumococcal isolates from the CSF of young children in Europe and in the United States and Canada. These analyses indicate that pneumococcal conjugate vaccines could potentially prevent a substantial proportion of episodes of bacteremic disease, pneumonia, meningitis, and otitis media, especially in young children.

Which pneumococcal serogroups cause the most invasive disease: implications for conjugate vaccine formulation and use, part I

We analyzed >70 recent data sets to compare the serogroups causing invasive pneumococcal disease (IPD) with those represented in conjugate vaccine formulations. Five to 8 and 10-11 serogroups comprise at least 75% of pneumococcal isolates from young children and older children/adults, respectively, in each geographic region. Serogroups in the 7-valent formulation (4, 6, 9, 14, 18, 19, and 23) cause 70%-88% of IPD in young children in the United States and Canada, Oceania, Africa, and Europe, and <65% in Latin America and Asia. Serogroups in the 9-valent formulation (7-valent+1, 5) cause 80%-90% of IPD in each region except Asia (66%). Serogroup 1 accounts for >6% of IPD in each region, including Europe, except the United States and Canada and Oceania. In contrast, several serogroups not found in 7-, 9-, and 11-valent conjugate formulations are significant causes of disease in older children/adults. Nevertheless, each conjugate formulation could prevent a substantial IPD burden in each region and age group.

Determination of antibody responses of elderly adults to all 23 capsular polysaccharides after pneumococcal vaccination

The 23-valent pneumococcal polysaccharide vaccine was formulated to prevent invasive infection in the elderly and other high-risk populations from the most prevalent Streptococcus pneumoniae serotypes. However, the immunogenicity of all 23 vaccine polysaccharides has not been fully characterized in elderly adults. We previously reported that whereas the majority of elderly subjects had vigorous immune responses to selected pneumococcal vaccine polysaccharides, a subset of elderly individuals responded to fewer than two of seven vaccine serotypes after immunization. To determine whether these elderly low responders have a general inability to respond to pneumococcal vaccine and to determine whether elderly low responders might be identified by their responses to a few polysaccharides, we measured antibody responses of elderly adults to all 23 vaccine polysaccharides after pneumococcal immunization. As a group, elderly subjects showed a significant rise after immunization in geometric mean antibody levels to all 23 vaccine serotypes. However, when individual rather than group immune responses were assessed, the 23-valent vaccine did not appear to be uniformly immunogenic in these elderly subjects. Eleven elderly subjects (20%) had twofold increases in specific antibody after vaccination to only 5 or fewer of the 23 vaccine polysaccharides, and they did not respond to the most prevalent serotypes causing invasive disease. Antibody responses to serotype 9N were found to reliably distinguish low vaccine responders from other elderly subjects. However, no particular group of vaccine polysaccharides could be used as a marker for adequate immune responses if only postvaccination sera were analyzed.

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.

An emergency department-based pneumococcal vaccination program could save money and lives

STUDY OBJECTIVE

Pneumococcal vaccination (PV) rates for eligible emergency department patients are less than 25%. This study determines the potential effect of an ED-based pneumococcal vaccination program in preventing pneumococcal bacteremia (PB) in high-risk patients.

METHODS

In a retrospective observational study, hospital records of 188 consecutive adults (>/=18 years old) with PB were reviewed to determine how many were treated in the ED from 1 to 72 months before their admission for bacteremia. Potential cost savings and mortality reductions from an ED-based PV program were calculated assuming PV prevents 65% of bacteremic episodes. A retrospective review of 10,650 ED charts determined the percentage of patients with PV indications and the relative frequency of indications.

RESULTS

One hundred four (55%) of the 188 patients with PB were seen in the ED less than or equal to 72 months before their admission for PB, and 91 (88%) of the 104 had indications for PV. These 91 patients had been evaluated in the ED an average of 3.4 times per patient during this 72-month period. Nine patients (10%) died before discharge. Mean hospital stay for the 82 survivors was 11.2 days. Of 10,650 ED charts reviewed, 2,011 (19%) had documented PV indications. Most prevalent PV indications were age 65 years or older (851 patients, 42%), diabetes mellitus (697, 35%), malignancy (248, 12%), chronic renal failure (228, 11%), and immunosuppression (221, 11%). Estimated cost savings ranged from $168,940 to $427,380.

CONCLUSION

ED-based PV programs would result in considerable cost savings and decreased mortality.

Complicated parapneumonic effusions in children caused by penicillin-nonsusceptible Streptococcus pneumoniae

OBJECTIVE

To describe the clinical characteristics of complicated parapneumonic effusions (CPE) in children caused by Streptococcus pneumoniae nonsusceptible to penicillin (PCN-N) and compare their clinical outcome with CPE caused by penicillin-susceptible (PCN-S) organisms.

DESIGN

Children with parapneumonic effusions were identified retrospectively between July 1992 and June 1996. Charts of patients with CPE were reviewed for data obtained at the time of hospital admission. In addition, outpatient charts and/or the families of children with CPE caused by PCN-N S pneumoniae were reviewed to identify specific risk factors associated with PCN-N organisms.

RESULTS

Sixty-four cases of CPE were identified during the 4-year period. In 26 cases a bacterial pathogen was recovered, with S pneumoniae accounting for 23 of these isolates (88%). Of the 23 S pneumoniae cases, 17 were PCN-S and 6 cases were nonsusceptible. Complicated parapneumonic effusions caused by PCN-N S pneumoniae occurred in significantly younger patients than CPE that were PCN-S (2.1 years vs 7.9 years). Nonsusceptible effusions also had a higher incidence of bacteremia than PCN-S effusions (100% vs 29%). There were no significant differences between the two groups for duration of chest tube drainage, febrile days, oxygen use, and hospital stay.

CONCLUSION

CPE caused by PCN-N S pneumoniae is associated with a younger age and higher rate of bacteremia than CPE caused by PCN-S strains. However, there were no significant differences in outcome measures between patients infected with susceptible or nonsusceptible organisms.

Levofloxacin in vitro activity against bacteremic isolates of Streptococcus pneumoniae. Franklin County Pneumonia Study Group

Levofloxacin had excellent activity in vitro against bacteremic isolates of Streptococcus pneumoniae with 495 (99.2%) of 499 isolates being susceptible. A total of 38 (97.4%) of 39 isolates with minimal inhibitory concentrations > or = 0.12 micrograms/ml of penicillin were susceptible to levofloxacin. There was excellent correlation between the disk diffusion and broth microdilution methods for determining susceptibility. Resistant isolates belonged to four different serotypes. There was no increase in proportion of isolates of S. pneumoniae resistant between 1991 and 1994.

Pneumococcal bacteremia in two tertiary care hospitals in Winnipeg, Canada. Pneumococcal Bacteremia Study Group

STUDY OBJECTIVE

To review experience with pneumococcal bacteremia at two Canadian tertiary care centers.

DESIGN

Retrospective record review.

SETTING

Two tertiary acute care teaching hospitals in Winnipeg, Manitoba.

PATIENTS

Patients identified with pneumococcal bacteremia during an 8-year period.

RESULTS

Hospital records were reviewed for 534 of 617 patients with pneumococcal bacteremia. The overall case fatality ratio was 70 (13%), varying from 3.2% in children to 43% in those older than 80 years. Twenty-seven (18%) hospitalized children and 68 (23%) adults required ICU admission. Duration of hospitalization was 14.9 +/- 24.9 and 11.0 +/- 19.1 days for children at the two institutions and 22.5 +/- 37.6 days and 38 +/- 93 days for adults. For the 217 viable pneumococcal strains studied, 89% were serotypes included in the present 23-valent vaccine. Documentation of prior vaccination was present for only 9 (1.7%) patients, although 281 (89%) adults and 99 (45%) children met criteria for vaccination.

CONCLUSIONS

Mortality in our population is similar to previous reports. More widespread pneumococcal vaccination in eligible populations may not only decrease mortality, but may also provide savings through decreased hospital admission and need for intensive care.