Controlling invasive pneumococcal disease: is vaccination of at-risk groups sufficient?

National recommendations for adult pneumococcal vaccination in countries of the WHO regions of Americas, Africa, Eastern Mediterranean, South East Asia, and Western Pacific

BACKGROUND

Adults who are elderly or who have underlying health conditions are at particular risk of Streptococcus pneumoniae infections, and pneumococcal vaccines are available. Nonetheless, only national recommendations from countries of North America and Europe have been previously reviewed in the literature.

METHODS

Consequently, we aimed to collate national guidelines for adult pneumococcal immunization across the 161 countries within the World Health Organization (WHO) regions-the Americas (except Canada and the United States of America), Africa, Eastern Mediterranean, South East Asia, and Western Pacific-from country-level official websites and documents, from the WHO portal, and from direct contact with public health officials, pertinent governmental sources, or local vaccination experts.

RESULTS

For 40.4 % (65/161) of these countries, adult pneumococcal vaccination information was available. Among these 65 with available information, 63.1 % (41/65) include adult pneumococcal vaccination in the national vaccination schedule: 58.5 % (24/41) recommend vaccination both for older adults and for risk groups, while 9.8 % (4/41) recommend it only for older adults, and 31.7 % (13/41) only for risk groups. Of note, among the 13 national risk based-only recommendations, 30.8 % (4/13) are age-dependent and strictly reserved for older adults. The regions where age-based adult pneumococcal vaccination recommendations seem to predominate are South East Asia, Western Pacific, and the Americas. The threshold for age-based pneumococcal vaccination recommendations varies between 50 and 70 years of age. The Americas has the highest proportion of countries with risk-based recommendations. Three-quarters of these countries include PCV and PPV23 in the recommendations, most often given in sequence.

CONCLUSIONS

Less than half of countries of the five WHO regions analyzed have accessible information on adult pneumococcal vaccination, and only 25.5 % (41/161) of all countries reviewed recommend adult pneumococcal immunization within the national vaccination schedule. Policymakers should consider extending pneumococcal vaccination guidelines-adapted to national priorities for adult healthcare-as based on local age demographics and risk factor predominance.

The Burden of Streptococcus pneumoniae-Related Admissions and In-Hospital Mortality: A Retrospective Observational Study between the Years 2015 and 2022 from a Southern Italian Province

Streptococcus pneumoniae (SP) has high worldwide incidence and related morbidity and mortality, particularly among children and geriatric patients. SP infection could manifest with pneumonia, bacteremia, sepsis, meningitis, and osteomyelitis. This was a retrospective study aimed at evaluating the incidence, comorbidities, and factors associated with in-hospital mortality of pneumococcal disease-related hospitalization in a province in southern Italy from the years 2015 to 2022. This study was performed in the Local Health Authority (LHA) of Pescara. Data were collected from hospital discharge records (HDRs): this database is composed of 288,110 discharge records from LHA Pescara's hospitals from 2015 to 2022. Streptococcus Pneumoniae-related hospitalizations were about 5% of the hospitalizations; 67% of these were without comorbidities; 21% were with one comorbidity; and 13% were with two or more comorbidities. Regarding mortality of SP infection, the most affected age group was older people, with the percentage of cases among the over-65s being more than 50% compared to the other age groups. HDRs represent a valid and useful epidemiological tool for evaluating the direct impact of pneumococcal disease on the population and also indirectly for evaluating the effectiveness of vaccination strategies and directing them.

Dissemination of Tn916-Related Integrative and Conjugative Elements in Streptococcus pneumoniae Occurs by Transformation and Homologous Recombination in Nasopharyngeal Biofilms

Multidrug resistance in Streptococcus pneumoniae (or pneumococcus) continues to be a global challenge. An important class of antibiotic resistance determinants disseminating in S. pneumoniae are >20-kb Tn916-related integrative and conjugative elements (ICEs), such as Tn2009, Tn6002, and Tn2010. Although conjugation has been implicated as the transfer mechanism for ICEs in several bacteria, including S. pneumoniae, the molecular basis for widespread dissemination of pneumococcal Tn916-related ICEs remains to be fully elucidated. We found that Tn2009 acquisition was not detectable via in vitro transformation nor conjugative mating with donor GA16833, yielding a transfer frequency of <10-7. GA16833 Tn2009 conjugative gene expression was not significantly induced, and ICE circular intermediate formation was not detected in biofilms. Consistently, Tn2009 transfer efficiency in biofilms was not affected by deletion of the ICE conjugative gene ftsK. However, GA16833 Tn2009 transfer occurred efficiently at a recombination frequency (rF) of 10-4 in dual-strain biofilms formed in a human nasopharyngeal cell bioreactor. DNase I addition and deletions of the early competence gene comE or transformation apparatus genes comEA and comEC in the D39 recipient strain prevented Tn2009 acquisition (rF of <10-7). Genome sequencing and single nucleotide polymorphism analyses of independent recombinants of recipient genotype identified ~33- to ~55-kb donor DNAs containing intact Tn2009, supporting homologous recombination. Additional pneumococcal donor and recipient combinations were demonstrated to efficiently transfer Tn916-related ICEs at a rF of 10-4 in the biofilms. Tn916-related ICEs horizontally disseminate at high frequency in human nasopharyngeal S. pneumoniae biofilms by transformation and homologous recombination of >30-kb DNA fragments into the pneumococcal genome. IMPORTANCE The World Health Organization has designated Streptococcus pneumoniae as a priority pathogen for research and development of new drug treatments due to extensive multidrug resistance. Multiple strains of S. pneumoniae colonize and form mixed biofilms in the human nasopharynx, which could enable exchange of antibiotic resistance determinants. Tn916-related integrative and conjugative elements (ICEs) are largely responsible for the widespread presence of macrolide and tetracycline resistance in S. pneumoniae. Utilizing a system that simulates colonization of donor and recipient S. pneumoniae strains in the human nasopharynx, efficient transfer of Tn916-related ICEs occurred in human nasopharyngeal biofilms, in contrast to in vitro conditions of planktonic cells with exogenous DNA. This high-frequency Tn916-related ICE transfer between S. pneumoniae strains in biofilms was due to transformation and homologous recombination, not conjugation. Understanding the molecular mechanism for dissemination of Tn916-related ICEs can facilitate the design of new strategies to combat antibiotic resistance.

Isolation and identification of Streptococcus pneumoniae serotype 6B from a patient with bacterial meningitis infection in Jakarta, Indonesia

CNS infection is a life-threatening condition in developing countries and Streptococcus pneumoniae has been reported as the most common cause of bacterial meningitis; however, there is limited data on pneumococcal meningitis in Indonesia. This cross-sectional study aimed to isolate and identity S. pneumoniae strains from cerebrospinal fluid (CSF) specimens collected as part of routine testing from patients with clinically diagnosed central nervous system infection at a national referral hospital in Jakarta, Indonesia in 2017. S. pneumoniae isolation and identification were performed using conventional culture and molecular tools. Antibiotic susceptibility patterns were monitored through minimum inhibitory concentration testing. From 147 CSF specimens, one S. pneumoniae strain was identified from a patient with bacterial meningitis symptoms. The isolate was serotype 6B (ST5661) and susceptible to 18 antimicrobial agents tested, including penicillin, tetracycline, and the macrolide group. Our data provide insights into the epidemiology of invasive pneumococcal disease in Indonesia.

Rates of Vaccination against Streptococcus Pneumoniae in Cochlear Implant Patients

BACKGROUND Streptococcus pneumoniae can cause life-threatening illness, with invasive pneumococcal diseases (IPD) like meningitis, sepsis, bacteremic pneumonia, and bacteremia being major causes of morbidity and mortality. Studies have shown that patients who have had a cochlear implant, particularly children, have an increased risk of bacterial (pneumococcal) meningitis. Vaccination in patients with cochlear implants is important and recommended universally. The World Health Organization recommends the use of pneumococcal conjugate vaccines in all countries and considers their use to be a priority in all national immunization programs. The objective of this study was to assess rates of vaccination against Streptococcus pneumoniae in patients with cochlear implants who were implanted at the Institute of Physiology and Pathology of Hearing, Poland. MATERIAL AND METHODS We analyzed data from questionnaires administered to 2,628 patients who visited the Implants and Auditory Perception Department (IAPD) of the Institute of Physiology and Pathology of Hearing between January 2014 and March 2016. RESULTS The percentage of vaccinated patients in the study group was 28.2%, most of whom (90.7%) were children. Among the children, 49.3% were vaccinated against S. pneumoniae, but the corresponding rate for adults was only 5.5%. CONCLUSIONS The percentage of patients with cochlear implants who received vaccination against S. pneumoniae was low, both in children and adults, but especially in adults comparing to available reports.

Molecular characterization of non-vaccine Streptococcus pneumoniae serotypes 11A, 15 B/C and 23A recovered from invasive isolates in Colombia

Introducción. En Colombia se recolectaron 192 aislamientos invasivos de Streptococcus pneumoniae de los serotipos 11A, 15B/C y 23A (no incluidos en las vacunas conjugadas) entre 1994 y 2014, como parte de las actividades del Sistema de Redes de Vigilancia de los Agentes Responsables de Neumonías y Meningitis Bacterianas (SIREVA II).Objetivo. Determinar las características moleculares de aislamientos invasivos de los serotipos 11A, 15B/C y 23A de S. pneumoniae recolectados en Colombia entre 1994 y 2014. Materiales y métodos. La caracterización molecular de los aislamientos se hizo mediante electroforesis en gel de campo pulsado (Pulse-Field Gel Electrophoresis, PFGE) y por tipificación de secuencias multilocus (Multilocus Sequence Typing, MLST).Resultados. El serotipo 11A mostró un grupo clonal representado por el ST62, en tanto que el serotipo 15B/C se distribuyó en tres grupos asociados con los clones Netherlands15B-37 ST199 (28,75 %), ST8495 (18,75 %) y SLV (variante en un solo locus) de ST193 (21,25 %). Los aislamientos con serotipo 23A se agruparon en tres grupos clonales; 70,21 % de ellos estaban estrechamente relacionados con el ST42, 17,02 % con el Colombia23F-ST338, y 6,38 % con el Netherlands15B-37 ST199.Conclusión. Los clones Colombia23F-ST338 y Netherlands15B-ST199 encontrados en este estudio abarcaron más serotipos de los reportados previamente por otros autores, incluido el serotipo 23A. Estos análisis revelan la importancia de la conmutación (switching) capsular en la expansión de clones exitosos entre los serotipos no vacunales como causa de enfermedad invasiva neumocócica.

Role of pneumococcal vaccination in prevention of pneumococcal disease among adults in Singapore

The burden of disease associated with Streptococcus pneumoniae infection in adults can be considerable but is largely preventable through routine vaccination. Although substantial progress has been made with the recent licensure of the new vaccines for prevention of pneumonia in adults, vaccine uptake rates need to be improved significantly to tackle adult pneumococcal disease effectively. Increased education regarding pneumococcal disease and improved vaccine availability may contribute to a reduction in pneumococcal disease through increased vaccination rates. The increase in the elderly population in Singapore as well as globally makes intervention in reducing pneumococcal disease an important priority. Globally, all adult vaccines remain underused and family physicians give little priority to pneumococcal vaccination for adults in daily practice. Family physicians are specialists in preventive care and can be leaders in ensuring that adult patients get the full benefit of protection against vaccine-preventable diseases. They can play a key role in the immunization delivery of new and routine vaccines by educating the public on the risks and benefits associated with vaccines. Local recommendations by advisory groups on vaccination in adults will also help to tackle vaccine preventable diseases in adults.

Serotyping of Streptococcus pneumoniae isolated from Tehran by Multiplex PCR: Are serotypes of clinical and carrier isolates identical?

BACKGROUND AND OBJECTIVES

Streptococcus pneumoniae is the most common cause of invasive infections among both young children and elderly people. Common serotypes causing invasive diseases and the emergence of carriers of Streptococcus pneumoniae in Iran is not yet known. Past-vaccine surveillance studies of serotype prevalence patterns in Iran are necessary to monitor the epidemiology of Streptococcus pneumoniae. Because of variation of pneumococcal serotypes in different geographical regions, in this study we evaluated common serotypes causing pneumococcal infections and healthy carrier children in Tehran by Multiplex PCR.

MATERIALS AND METHODS

A total of 150 nasopharyngeal swabs were collected from healthy children in Tehran between December 2011 and August a2012, and 100 clinical samples were collected. Identification was performed by biochemical and molecular tests. Serotyping was done by multiplex PCR. We designed primers based on the sequences available for the routine capsular types and combined them into six multiplex PCR.

RESULTS

From 150 nasopharyngeal swabs, 40 isolates of Streptococcus pneumoniae were identified after identification tests. Thirty six clinical isolates were also detected among clinical samples. Four serotypes (19A, 6, 3, 23F) of S. pneumoniae accounted for 55.7% of both sets of strains isolated from nasal carriage and clinical samples. Serotype 19A was the most common serotype among both groups.

CONCLUSION

The multiplex PCR approach was successfully adapted to identify serotypes from more than 91% of the isolates tested. Among S. pneumoniae isolates in Tehran, the most prevalent serotypes were similar among carriage and invasive isolates. Continued monitoring of common serotypes of Streptococcus pneumoniae is essential for future vaccine formulation in Iran.

Antimicrobial resistance of Streptococcus pneumoniae in Southeast Austria, 1997-2008

Antibiotic resistance in Streptococcus pneumoniae has increased worldwide but varies within geographical regions. We conducted a retrospective analysis of resistance in S. pneumoniae over a 12-year period to assess local and temporal trends in antibacterial resistance. From 1997 to 2008, a total of 1814 non-duplicate S. pneumoniae isolates were identified at the Institute of Hygiene, Microbiology and Environmental Medicine, Medical University of Graz, Austria. Antibiotic resistance was determined by the Clinical and Laboratory Standards Institute (CLSI) disk diffusion test. For penicillin, the minimum inhibitory concentration was determined by Etest. Susceptibility was defined according to CLSI interpretive criteria. For penicillin, resistance rates were consistently low at 0.2% over the 12-year study period. An increase in resistance was remarkable for erythromycin (3.5% in 1997; 14.7% in 2008), clindamycin (1.8% in 1997; 10.6% in 2008) and tetracycline (1.8% in 2000; 11.0% in 2008). For trimethoprim/sulfamethoxazole, resistance increased slightly to 9.2% in 2008. Quinolones showed a low resistance rate of 0.2% that persisted over the whole study period. In contrast to previously published national data, resistance to penicillin was observed to remain at a remarkably low and constant level. Although international surveillance programmes have set up sustainable and interlinked data networks, our results suggest that regional surveillance may still be needed as decision support for appropriate empirical antibiotic therapy in the local health setting.

Identification of new risk factors for pneumonia: population-based case-control study

BACKGROUND

Certain conditions are established as risk factors for community-acquired pneumonia. There are a number of other conditions that may also be risk factors, but information on these is limited.

AIM

To determine new independent risk factors for community-acquired pneumonia using a very large primary care database.

DESIGN OF STUDY

Nested case-control study.

SETTING

Four hundred and forty-three general practices in the UK contributing to the QRESEARCH database.

METHOD

A total of 17 172 incident cases of all ages diagnosed with pneumonia between 1996 and 2005 were matched with up to five controls by age, sex, general practice, and calendar year. Associations between pneumonia and each established condition and potential risk factors were determined with odds ratios (ORs), using multiple conditional logistic regression analysis adjusted for smoking, socioeconomic status, and use of influenza and pneumococcal vaccines.

RESULTS

The analysis confirmed the higher risk of pneumonia among patients with at least one of the established risk factors; the adjusted OR was 2.29 (95% confidence interval [CI]=2.20 to 2.39). In addition, patients with the following conditions had a higher risk of pneumonia despite adjustment for known risk factors and confounders: stroke or transient ischaemic attack, rheumatoid arthritis, Parkinson's disease, cancers, multiple sclerosis, dementia, and osteoporosis. The adjusted OR for pneumonia among patients without an established risk factor but with at least one of the new conditions was 2.44 (95% CI=2.24 to 2.65).

CONCLUSION

As well as confirming some established risk factors, this study has determined seven new independent risk factors for community-acquired pneumonia.

National paediatric immunization program of high risk groups: no effect on the incidence of invasive pneumococcal diseases

This study monitors the epidemiology of invasive pneumococcal diseases (IPD) in hospitalized children up to 60 months of age before (February 2001-October 2004) and after (November 2004-January 2007) the introduction of a national risk group immunization program with "Prevenar" in Austria. The IPD incidence rates, per 100,000, for IPD were 7.6 before and 6.4 after the risk group immunization program, while there was a significant reduction (p<0.05) for meningitis, 3.1 before and 1.6 after. Overall, the most commonly observed serotypes were 14 (34.2%), 6B (11.7%), and 23F (6.7%). 71.7% of the identified strains were vaccine types; 12.5% were vaccine-related serotypes. No clinically relevant changes in the incidence rate of IPDs or shift/replacement of serotypes was documented. Antimicrobial resistance predominated against erythromycin (32.5%) and clarithromycin (26.7%). Our data show that this risk group vaccination program had no impact on the incidence of IPD in young children.

Herd immunity: recent uses in vaccine assessment

Human communities defend themselves against specific infectious agents in a way that extends beyond the simple sum of the immune status of its individuals. By analogy with individual immunity to specific agents, the community level of immunity may vary from complete susceptibility to full protection. Herd immunity has been used to name this community property, which is the result of evolution through natural selection, leading to relationships between two species, typical of prey-predator systems. Varying uses of the term herd immunity led to the use of other expressions, such as herd protection, herd effect and community immunity. Knowledge derived from observational studies and models on herd immunity has supported decisions on the choice of vaccines and vaccination strategies for the benefit of populations. This knowledge is most likely to be extended in the future, with far-reaching effects.

Protection from Streptococcus pneumoniae keratitis by passive immunization with pneumolysin antiserum

PURPOSE

To determine whether passive immunization with pneumolysin antiserum can reduce corneal damage associated with pneumococcal keratitis.

METHODS

New Zealand White rabbits were intrastromally injected with Streptococcus pneumoniae and then passively immunized with control serum, antiserum against heat-inactivated pneumolysin (HI-PLY), or antiserum against cytotoxin-negative pneumolysin (psiPLY). Slit lamp examinations (SLEs) were performed at 24, 36, and 48 hours after infection. An additional four corneas from rabbits passively immunized with antiserum against psiPLY were examined up to 14 days after infection. Colony forming units (CFUs) were quantitated from corneas extracted at 20 and 48 hours after infection. Histopathology of rabbit eyes was performed at 48 hours after infection.

RESULTS

SLE scores at 36 and 48 hours after infection were significantly lower in rabbits passively immunized with HI-PLY antiserum than in control rabbits (P < or = 0.043). SLE scores at 24, 36, and 48 hours after infection were significantly lower in rabbits passively immunized with psiPLY antiserum than in control rabbits (P < or = 0.010). The corneas of passively immunized rabbits that were examined up to 14 days after infection exhibited a sequential decrease in keratitis, with an SLE score average of 2.000 +/- 1.586 at 14 days. CFUs recovered from infected corneas were not significantly different between each experimental group and the respective control group at 20 or 48 hours after infection (P > or = 0.335). Histologic sections showed more corneal edema and polymorphonuclear leukocyte (PMN) infiltration in control rabbits compared with passively immunized rabbits.

CONCLUSIONS

HI-PLY and psiPLY both elicit antibodies that provide passive protection against S. pneumoniae keratitis.

Burden of paediatric invasive pneumococcal disease in Europe, 2005

Within the European Union (EU), documenting the burden of invasive pneumococcal disease (IPD) in infants and children is important for coordinating effective pneumococcal immunization policies. Our objective was to document the burden of IPD in countries of the EU plus Switzerland and Norway. European affiliates of Wyeth Vaccines made available recent epidemiological data on IPD from local disease surveillance programmes, including unpublished sources. Recent literature and websites were also searched to provide as wide a representation as possible. This included OVID and abstracts from a number of international meetings, dating from the year 2000. The reported rates of paediatric IPD per 100000 (age) ranged from a low of 1.7 (<2 years) to 4.2 (2-15 years) in Sweden to a high of 93.5 to 174 (<2 years) to 56.2 (<5 years) in Spain. The percentage of circulating serotypes causing IPD that are covered by 7-valent pneumococcal conjugate vaccine (PCV) IPD serotype coverage ranged from 60% to 80% for European children aged <2 years. Under reporting, differences in reporting methods, antibiotic prescribing and disparities in blood-culturing practices may explain the differences in reported disease incidence. Because of the excellent clinical efficacy of the PCV against IPD, national pneumococcal vaccination programmes in Europe have the potential to prevent much morbidity and mortality.