A decade (1989-1998) of pediatric invasive pneumococcal disease in 2 populations residing in 1 geographic location: implications for vaccine choice

A Nationwide Outbreak of Invasive Pneumococcal Disease in Israel Caused by Streptococcus Pneumoniae Serotype 2

BACKGROUND

Invasive pneumococcal disease (IPD) caused by Streptococcus pneumoniae serotype 2 (Sp2) is infrequent. Large scale outbreaks have not been reported following pneumococcal conjugate vaccine (PCV) implementation. We describe a Sp2 IPD outbreak in Israel, in the 13-valent PCV (PCV13) era, with focus on Sp2 population structure and evolutionary dynamics.

METHODS

The data derived from a population-based, nationwide active surveillance of IPD since 2009. 7-valent PCV (PCV7)/PCV13 vaccines were introduced in July 2009 and November 2010, respectively. Sp2 isolates were tested for antimicrobial susceptibility, Multilocus Sequence Typing (MLST) and Whole Genome Sequencing (WGS) analysis.

RESULTS

Overall, 170 Sp2 IPD cases were identified during 2009-2019; Sp2 increased in 2015 and caused 6% of IPD during 2015-2019, a 7-fold increase compared with 2009-2014.The outbreak was caused by a previously unreported molecular type (ST-13578), initially observed in Israel in 2014. This clone caused 88% of Sp2 during 2015-2019. ST-13578 is a single-locus variant of ST-1504, previously reported globally, including in Israel. WGS analysis confirmed clonality among the ST-13578 population. Single-nucleotide polymorphisms-dense regions support a hypothesis that the ST-13578 outbreak clone evolved from ST-1504 by recombination.All tested strains were penicillin-susceptible (MIC <0.06 μg/mL). The ST-13578 clone was identified almost exclusively (99%) in the Jewish population and was mainly distributed in 3/7 Israeli districts. The outbreak is still ongoing, although declining since 2017.Conclusions: To the best of our knowledge, this is the first widespread Sp2 outbreak since PCV13 introduction worldwide, caused by the emerging ST-13578 clone.

Understanding the Evolution of Antibiotic-nonsusceptible Pneumococcal Nasopharyngeal Colonization Following Pneumococcal Conjugate Vaccine Implementation in Young Children

BACKGROUND

Four main processes determine pneumococcal conjugate vaccine (PCV) antibiotic-nonsusceptible Streptococcus pneumoniae (ANSP) carriage: reduction of PCV serotypes, increase of non-PCV serotypes, potential overall reduction in carriage, and within-serotype nonsusceptibility resulting from continuous antibiotic pressure. The post-PCV implementation dynamics of these components were examined in young children from 2 distinct ethnic populations: Jewish and Bedouin.

METHODS

We performed ongoing, prospective, population-based, active surveillance initiated at the time of 7- and 13-valent PCVs (PCV7; PCV13) implementation. Nasopharyngeal cultures for S. pneumoniae were obtained daily from children aged <5 years who visited the only pediatric emergency room in the district during a 6-year period (2009 to 2015).

RESULTS

Of 8446 nasopharyngeal samples, 48.3% were positive (42.0% and 52.8% for Jewish and Bedouin children, respectively; P < .001). Nonsusceptibility was significantly more frequent among PCV serotypes than among non-PCV serotypes and among Bedouin children than among Jewish children. PCV serotype carriage declined by 80%, while that of non-PCV serotypes increased by 140%. The overall (all serotypes) pneumococcal carriage significantly declined (33% and 11% in Bedouin and Jewish children, respectively). Among non-PCV isolates, the proportion of ANSP significantly increased with time in both populations. As a summation of all 4 processes, ANSP carriage significantly decreased among both Bedouin and Jewish children.

CONCLUSIONS

PCV impact on ANSP nasopharyngeal carriage is a dynamic, multicomponent process, highly dependent on antibiotic consumption in the community, which may result in a continuous increase in antibiotic resistance in the replacing serotypes.

Quantification and Characterization of Antimicrobial Resistance in Greywater Discharged to the Environment

In disenfranchised communities, untreated greywater (wastewater without sewage) is often environmentally discharged, resulting in potential human exposure to antimicrobial-resistant bacteria (ARB), including extended-spectrum beta-lactamase (ESBL) producers. We sought to examine the abundance of ARB, specifically ESBLs, and antimicrobial resistance genes (ARGs) in greywater from off-grid, pastoral Bedouin villages in Southern Israel. Greywater samples (n = 21) collected from five villages were analyzed to enumerate fecal coliforms and Escherichia coli. ESBL producers were recovered on CHROMagar ESBL and confirmed by VITEK®2 (bioMerieux, Marcy l’Etoile, France) for identification and antimicrobial susceptibility testing. Total genomic DNA was extracted from greywater samples and quantitative PCR (qPCR) was used to determine relative abundance (gene copies/16S rRNA gene) of class 1 integron-integrase intI1, blaTEM, blaCTX-M-32, sul1, and qnrS. The mean count of presumptive ESBL-producing isolates was 4.5 × 106 CFU/100 mL. Of 81 presumptive isolates, 15 ESBL producers were recovered. Phenotypically, 86.7% of ESBL producers were multi-drug resistant. Results from qPCR revealed a high abundance of intI1 (1.4 × 10−1 gene copies/16S rRNA), sul1 (5.2 × 10−2 gene copies/16S rRNA), and qnrS (1.7 × 10−2 gene copies/16S rRNA) followed by blaTEM (3.5 × 10−3 gene copies/16S rRNA) and blaCTX-M-32 (2.2 × 10−5 gene copies/16S rRNA). Results from our study indicate that greywater can be a source of ARB, including ESBL producers, in settings characterized by low sanitary conditions and inadequate wastewater management.

The Infectious and Noninfectious Etiology, Clinical Picture and Outcome of Neutropenia in Immunocompetent Hospitalized Children

BACKGROUND

Acquired neutropenia in immunocompetent children is common, and its differential diagnosis ranges from benign causes to life-threatening diseases. We described the etiology, clinical picture and outcome of new-onset neutropenia in immunocompetent children assessed in the emergency department and hospitalized at our medical center.

METHODS

Previously healthy children admitted with neutropenia (absolute neutrophil count <1.5 × 10(9)/L) were included. Serious bacterial infections were defined as culture-positive blood, urine, cerebrospinal fluid, articular fluid or stool infections, pneumonia, Brucellosis and Rickettsiosis.

RESULTS

A total of 601 patients (5 days-202 months old) were enrolled; 3 (0.5%), 48 (8%), 165 (27.5%) and 385 (64%) had absolute neutrophil counts <0.2, 0.2-0.5, 0.5-1.0 and 1.0-1.5 × 10(9)/L, respectively. Associated leukopenia and thrombocytopenia were diagnosed in 186 (39%) and 71 (11.8%) patients. Three hundred sixteen of 601 (52.6%) and 519 of 601 (86.4%) were <2 or 36 months of age, respectively. Fever at admission was present in 27.6% patients. Serious bacterial infections were diagnosed in 106 (17.6%) patients. Brucellosis and rickettsiosis were diagnosed in 8 of 52 (15.4%) and 9 of 39 (23.1%) tests obtained. Respiratory syncytial virus was diagnosed in 17 of 33 (51.5%) nasal washes. An infectious etiology was determined in 171 (28.5%) patients. Acute leukemia was diagnosed in 6 patients. A significant correlation was found between resolution of neutropenia and patient age, infectious etiology and severity of neutropenia.

CONCLUSIONS

(1) Severe neutropenia was rare; (2) More than half of patients were <2 months of age; (3) An infectious etiology was diagnosed in a high number of patients, and serious bacterial infections were frequent and (4) Brucella spp. and rickettsial infections were frequent etiologies associated with neutropenia in our setting.

Performance of risk stratification criteria in the management of febrile young infants younger than three months of age

AIM

We evaluated the diagnosis, risk stratification and management of febrile infants under three months of age who presented to an Israeli paediatric emergency room (ER).

METHODS

This retrospective study enrolled all febrile infants examined in the paediatric ER of Soroka Medical Center during 2010-2013. The patients were classified into low-risk and high-risk subgroups and compared by age and ethnicity.

RESULTS

Overall, 2251 febrile infants (60.5% of Bedouin and 34.4% of Jewish ethnicity) were enrolled. Hospitalisation rates were higher among Bedouin vs. Jewish infants (55 vs. 39.8%, p < 0.001). Fever without localising signs was diagnosed in 1028 (45.6%) infants and 499 (48.5%) were hospitalised; 26% were stratified as high-risk and 74% as low-risk. Bedouin infants rates were more likely to be at high-risk (p = 0.001) and hospitalised (p < 0.001) than Jewish infants. With regard to low-risk infants, the incidence rates were higher before two months than two to three months of age (73.3 vs. 59%, p < 0.001), as were the hospitalisation rates (46.3 vs. 20.1%, p < 0.001). No differences were recorded for the hospitalisation rates of Bedouin and Jewish infants between the three daily shifts.

CONCLUSION

Major differences were recorded in hospitalisation rates, risk stratification and management of Bedouin and Jewish infants with fever without localising signs.

What is Known About Health and Morbidity in the Pediatric Population of Muslim Bedouins in Southern Israel: A Descriptive Review of the Literature from the Past Two Decades

The Bedouins comprise one of the ethnic groups in Israeli society. They are Muslims, most of who live in the Negev desert region of southern Israel and live by their unique traditions and customs. At the present they are going through a period of "society in transition", a unique condition that has ramifications for health and morbidity. In recent years the number of publications on the health of Bedouins in the Negev has increased. Recognition of unique socio-economic features, characteristics of health and diseases can help the medical team treat various health problems in this population as well as other populations with similar characteristics. In the present paper we survey and discuss publications on the health of Bedouin children over the past 20 years.

Epidemiologic and Microbiologic Characteristics of Occult Bacteremia Among Febrile Children in Southern Israel, Before and After Initiation of the Routine Antipneumococcal Immunization (2005-2012)

BACKGROUND

Little is known about the incidence and dynamics of occult bacteremia (OB) among infants/young children following the introduction of pneumococcal conjugate vaccines (PCVs) into the national immunization program in Israel in 2009-2010. The aim of this study was to characterize the epidemiologic and microbiologic picture of OB among febrile infants/children aged 3-36 months in southern Israel, before and after PCVs introduction.

METHODS

Retrospective study enrolling all infants/young children attending the emergency room of a tertiary medical center in southern Israel with fever without source, discharged, and reported with a positive blood culture.

RESULTS

Of 453 true bacteremias, 89 (19.6%) were defined as OB. OB rate was 0.22%; a significant decrease was recorded in OB rates, with the highest rate during 2005 (0.34%) and the lowest during 2011 (0.15%). OB cases decreased in post-PCV (2010-2012) versus prevaccination period (2005-2009) from 66/22,256 cases (0.3%) to 23/13,213 cases (0.17%; p = 0.03). Most frequent single OB pathogens were Streptococcus pneumoniae, Streptococcus viridans spp., and Kingella kingae (39.3%, 10.1%, and 9.0%, respectively); Enterobacteriaceae spp. were isolated in 10 cases (11.2%). No changes were recorded in S. pneumoniae-OB cases; K. kingae-OB decreased significantly (p = 0.047). None of the S. pneumoniae serotypes isolated during 2011-2012 belonged to 13-valent PCV (PCV13). An increase in non PCV13 serotypes was recorded during 2011-2012 (3/3, 100% vs. 7/32, 21.9%, p = 0.01).

CONCLUSION

OB rates decreased significantly following the introduction of PCVs. S. pneumoniae was the most frequent isolated pathogen in OB, but in lower percentages compared with the medical literature. No PCV13 serotypes were detected as a cause of OB during 2011-2012.

The Epidemiologic, Microbiologic and Clinical Picture of Bacteremia among Febrile Infants and Young Children Managed as Outpatients at the Emergency Room, before and after Initiation of the Routine Anti-Pneumococcal Immunization

We described the occult bacteremia (OB) and bacteremia with diagnosed focus (BwF) picture among children managed as outpatients at the pediatric emergency room (PER) in southern Israel, before and after the introduction of pneumococcal conjugate vaccines (PCVs) introduction in a retrospective study enrolling all three- to 36-month-old patients with fever >38.0 °C during 2005–2014. Of 511 (0.82% of all febrile patients) true bacteremias, 230 (45%) were managed as outpatients; 96 of 230 (41.7%) had OB and 134 (3.59%) had BwF. OB and BwF rates were 0.22% and 3.02%, respectively. A significant decrease was noted in OB and BwF rates (p = 0.0008 and p = 0.02, respectively). S. pneumoniae (SP, 37.5%), K. kingae (11.4%) and Brucella spp. (8.7%) were the most common OB pathogens and SP (29.8%), S. viridans (13.4%), and Brucella spp. (12.7%) were the most common in BwF patients. PCV13 serotypes were not found among the serotypes isolated post-PCV13 introduction. During 2010–2014 there was an increase in non-PCV13 serotype isolation (p = 0.005). SP was the main pathogen isolated among patients with pneumonia, acute otitis media (AOM) and periorbital cellulitis (62.5%, 33.3% and 60%, respectively). OB and BwF decreased following the introduction of PCVs and SP was the main pathogen in both conditions. Vaccine-SP serotypes were not isolated in OB after PCV13 introduction and non-vaccine serotypes increased significantly.

Epidemiological, diagnostic, clinical, and therapeutic aspects of Brucella bacteremia in children in southern Israel: a 7-year retrospective study (2005-2011)

BACKGROUND

Data on the various aspects of brucellosis in children living in southern Israel are missing.

OBJECTIVES

Our aim was to study the epidemiological, microbiological, diagnostic, clinical, therapeutic and outcome features of brucellosis in children <19 years of age in southern Israel during 2005-2011.

PATIENTS AND METHODS

The study population included all patients hospitalized with a diagnosis of brucellosis, established according to a clinical presentation compatible with brucellosis+presence of Brucella bacteremia (BB).

RESULTS

A total of 128 (50.8%) of 252 patients admitted with a diagnosis of brucellosis had BB (all with Brucella melitensis). All patients were of Muslim Bedouin ethnicity. The mean incidence of BB in southern Israel was 16 cases/100,000 Bedouin, with no significant changes during the study period. Overall duration of symptoms before diagnosis was 10.1±10.9 days. Fever at diagnosis was recorded in <20% of the patients. The most frequent symptoms were arthralgia (61.7%), weakness (32.8%), gastrointestinal disturbances (27.3%), myalgia (25%), and headache (18.8%). The main clinical findings included monoarthritis (36.7%), hepatosplenomegaly (25%), lymphadenopathy (17.2%), heart murmur (11.7%), and skin rash (9.4%), respectively. Anemia, leukopenia, thrombocytopenia, and pancytopenia were reported in 17.6%, 29.6%, 12.8%, and 2.3% of the patients, respectively. Twenty-nine (30.5%) patients with BB had serum agglutinin titers ≤1/160 (13, 13.7%%, had titers <1/160). Twenty-seven (93%) of the 29 patients aged 0-4 years were treated with gentamicin and trimethoprim-sulfamethoxazole; a total of 77 (60.2%) patients received gentamicin and doxycycline.

CONCLUSIONS

Childhood brucellosis remains an important public health problem in southern Israel. BB was diagnosed in >50% of the children with brucellosis, and B. melitensis was identified in all cases. Arthralgia, weakness, and gastrointestinal complaints were the most common symptoms, and monoarthritis, hepatosplenomegaly, and lymphadenopathy were the most common clinical findings. A considerable number of patients with BB had undetectable/low serum agglutinin titers, suggesting insufficient reliability on serology alone in diagnosis of brucellosis.

Differential impact of pneumococcal conjugate vaccines on bacteremic pneumonia versus other invasive pneumococcal disease

BACKGROUND

Bacteremic pneumonia (BP) accounts for ~35% of invasive pneumococcal disease (IPD) in young children. Our aims were to compare age, seasonal and serotype distribution of BP versus non-BP IPD and to determine whether the impact of the sequential 7/13-valent pneumococcal conjugate vaccine (PCV7/PCV13) introduction on disease incidence differed between BP and non-BP IPD in children <5 years of age.

METHODS

A nationwide, prospective, population-based, active surveillance (July 2004-June 2013) was conducted. All IPD episodes were included. PCV7 was introduced to the Israeli National Immunization Plan in July 2009 and has been replaced by PCV13 since November 2010.

RESULTS

In all, 983 (36.8%) BP and 1687 (63.2%) non-BP IPD episodes were recorded. A higher proportion of BP than that of non-BP IPD episodes (42.0% vs. 20.7%; P < 0.001) occurred in children >24 months old. Seasonality differed between BP and non-BP IPD, with yearly earlier peaks of non-BP IPD. The proportion of the 5 additional PCV13 serotypes (1, 3, 5, 7F and 19A) was higher in children with BP versus non-BP IPD (39.6% vs. 23.6%; P < 0.01). Shortly after PCV7 introduction, non-BP IPD rate was significantly reduced but that of BP was not. However, PCV13 introduction resulted in rapid reduction of BP rate, with a further reduction of non-BP IPD.

CONCLUSION

The differences in age distribution, seasonality and serotype distribution between BP and non-BP IPD suggest that the pathogenesis of these 2 entities is not identical and resulted in different impact rate dynamics after PCV7 and PCV13 introduction.

Acute mastoiditis in children under 15 years of age in Southern Israel following the introduction of pneumococcal conjugate vaccines: a 4-year retrospective study (2009-2012)

OBJECTIVES

To describe the epidemiologic, microbiologic, clinical and therapeutic aspects of acute mastoiditis (AM) in children <15 years of age during the 4-year period (2009-2012) following the introduction of pneumococcal conjugate vaccines in Israel.

PATIENTS AND METHODS

The medical records of all children with a discharge diagnosis of AM were reviewed.

RESULTS

A total of 66 AM episodes occurred in 61 patients. Forty-four (66.6%) cases occurred among patients <4 years, recent acute otitis media (AOM) history was reported in 27.1% and 28.8% patients received previous antibiotics for AOM. Postauricular swelling, postauricular sensitivity, protrusion of auricle and postauricular edema (93.8%, 90.6%, 85.9% and 95.7%, respectively) were the most common signs of AM. Leukocytosis >15,000 WBC/mm(3) was found in 39 (59.1%) cases. Cultures were performed in 52/66 episodes (positive in 27, 51.92% episodes), with recovery of 32 pathogens. The most frequently isolated pathogens were Streptococcus pneumoniae (15/52, 28.85%), Streptococcus pyogenes (9, 17.3%) and nontypeable Haemophilus influenzae (5, 9.62%). Eight (53.3%) S. pneumoniae isolates were susceptible to penicillin. Mean incidence of overall and pneumococcal AM were 11.1 and 2.58 cases/100000, with no significant changes during the study years. Surgical intervention was required in 19 (28.8%) patients.

CONCLUSIONS

(1) AM occurs frequently in patients without previous AOM history and with no previous antibiotic treatment; (2) S. pneumoniae and S. pyogenes continued to be the main etiologic agents of AM during the postvaccination period; (3) No changes were recorded in overall AM incidence and in pneumococcal AM incidence during the postvaccination period.

Near-elimination of otitis media caused by 13-valent pneumococcal conjugate vaccine (PCV) serotypes in southern Israel shortly after sequential introduction of 7-valent/13-valent PCV

BACKGROUND

Otitis media (OM) is common in early childhood. Streptococcus pneumoniae caused approximately 30%-60% of episodes before the pneumococcal conjugate vaccine (PCV) era. The 7-valent PCV (PCV7) was introduced to the Israeli National Immunization Plan in July 2009, and was gradually replaced by the 13-valent PCV (PCV13) starting in November 2010. We aimed at assessing the impact of PCV7/PCV13 sequential introduction on pneumococcal and overall OM necessitating middle ear fluid culture in children aged <2 years in southern Israel.

METHODS

This was a prospective, population-based, active surveillance. Our medical center is the only one in the region, enabling incidence calculation. All pneumococcal episodes submitted for culture between July 2004 and June 2013 were included. Three subperiods were defined: pre-PCV, PCV7, and PCV13.

RESULTS

Overall, 6122 OM episodes were recorded, and 1893 were pneumococcal. Compared with the pre-PCV period, OM caused by PCV7 plus serotype 6A and the 5 additional PCV13 serotypes (5VT : 1, 3, 5, 7F, 19A) decreased by 96% and 85%, respectively (incidence rate ratios [IRRs], 0.04 [95% confidence interval {CI}, .02-.08] and 0.15 [95% CI, .07-.30], respectively) in a 2-step pattern: In the PCV7 period, only OM caused by PCV7 + 6A serotypes was decreased; in the PCV13 period, 5VT OM rates decreased, along with an additional PCV7 + 6A OM reduction. A nonsignificant increase in non-PCV13 serotype OM was observed (IRR, 1.07 [95% CI, .72-1.58]). In total, 77% and 60% reductions of all-pneumococcal and all-cause OM incidences, respectively, were observed.

CONCLUSIONS

A substantial 2-step reduction of pneumococcal OM rates, with near-elimination of PCV13 disease, was observed shortly after PCV7/PCV13 introduction.

Increased risk for respiratory syncytial virus-associated, community-acquired alveolar pneumonia in infants born at 31-36 weeks of gestation

BACKGROUND

We compared hospitalization and pediatric intensive care unit (PICU) admission rates for community-acquired alveolar pneumonia (CAAP) and respiratory syncytial virus (RSV)-associated CAAP (RSV-CAAP) in non-RSV-immunized children <24-month-old born at 31-36 weeks gestational age (GA) versus those born at term (>36 weeks GA).

METHODS

Nasopharyngeal samples for RSV were obtained prospectively (2004-2011) during RSV season, from hospitalized children with radiographic-diagnosed CAAP. Soroka University Medical Center is the only hospital in the region, enabling population-based rate calculation. Relative risks (RR) and 95% confidence intervals (95% CI) were calculated comparing RSV-CAAP incidence in 31-36 weeks GA with >36 weeks GA children.

RESULTS

CAAP hospitalization incidences (per 1000 population) were 23.6 and 9.4 (RR: 2.52; 95% CI: 2.13-2.68), respectively; the respective incidences of PICU admission for overall CAAP were 1.8 and 0.2 (RR: 7.88; 95% CI: 4.59-11.83). The RRs (and 95% CI) for RSV-CAAP hospitalizations and PICU admission rates were (after extrapolation) 15.2 and 5.8 (RR: 2.79; 95% CI: 2.31-3.06) and 1.1 and 0.1 (RR: 9.14; 95% CI: 4.93-16.96), respectively. In a multiregression analysis in patients with RSV-CAAP versus CAAP, 31-36 weeks GA was an independent risk factor for hospitalization (RR: 1.485; 95% CI: 1.03-2.14).

CONCLUSIONS

Children <24-month-old born at 31-36 weeks GA are at increased risk for hospitalization and PICU admission for both overall CAAP and RSV-associated CAAP compared with those born at >36 weeks GA. Moreover, in late premature children, RSV represented a 50% increased risk for CAAP compared with infants born at term.

Early impact of sequential introduction of 7-valent and 13-valent pneumococcal conjugate vaccine on IPD in Israeli children <5 years: an active prospective nationwide surveillance

BACKGROUND

The 7-valent pneumococcal conjugated vaccine (PCV7) was introduced to the Israeli national immunization plan (NIP) in July 2009 (administered at age 2, 4 and 12 months), with a fast reduction of invasive pneumococcal disease (IPD) caused by PCV7 serotypes. Starting in November 2010, PCV13 gradually replaced PCV7.

AIM

To report the impact of PCV7/PCV13 sequential introduction on IPD in Israeli children <5 years.

METHODS

An ongoing nationwide, prospective, population-based, active surveillance. All IPD episodes (Streptococcus pneumoniae isolated from blood and/or cerebrospinal fluid) from July 2004 through June 2013 were included.

RESULTS

Overall, 2670 IPD episodes were recorded. Incidence of IPD caused by PCV7+6A serotypes during the PCV13 period vs. pre-PCV period decreased by 95% (Incidence Rate Ratio [IRR]=0.05; 95% CI=0.03-0.09). This reduction was observed in a two-step manner: 90% in the PCV7-period and further 5% in the PCV13-period. The rates of IPD caused by the 5 additional PCV13-serotypes (1, 3, 5, 7F, 19A; 5VT) increased initially by 47%, but subsequently decreased by 79%, resulting in an overall 70% reduction during the entire study period (IRR=0.30; 0.21-0.44). A two-fold increase in non-PCV13 serotypes IPD was observed (IRR=2.43; 1.73-3.66). In total, a 63% reduction of all-serotype IPD episodes was observed in children <5 years (69% and 48% in children <2 and 2-4 years old, respectively).

CONCLUSIONS

After initiation of PCV NIP, a rapid and substantial 2-step IPD reduction was observed in children <5 years. The serotype-specific rate reduction reflected the sequential introduction of PCV7/PCV13.

Influence of pneumococcal vaccines and respiratory syncytial virus on alveolar pneumonia, Israel

Postlicensure surveillance of pneumonia incidence can be used to estimate whether pneumococcal conjugate vaccines (PCVs) affect incidence. We used Poisson regression models that control for baseline seasonality to determine the impact of PCVs and the possible effects of variations in virus activity in Israel on these surveillance estimates. PCV was associated with significant declines in radiologically confirmed alveolar pneumonia (RCAP) among patients <6 months, 6–17 months, and 18–35 months of age (–31% [95% CI –51% to –15%], –41% [95% CI –52 to –32%], and –34% [95% CI –42% to –25%], respectively). Respiratory syncytial virus (RSV) activity was associated with strong increases in RCAP incidence, with up to 44% of cases attributable to RSV among infants <6 months of age and lower but significant impacts in older children. Seasonal variations, particularly in RSV activity, masked the impact of 7-valent PCVs, especially for young children in the first 2 years after vaccine introduction.

Invasive pneumococcal disease in Jamaican children

A 5-year retrospective review of cases of invasive pneumococcal disease admitted to the Bustamante Hospital for Children, Jamaica was conducted. A total of 111 cases were identified. The estimated incidence of invasive pneumococcal disease in Kingston and St Andrew was 21/100,000 children under the age of 10 years. The majority of cases (76%) were in the under-2-years age group. All four deaths were of infants. Pre-existing medical conditions included sickle cell disease, HIV and undernutrition. The rate of resistance to penicillin was 13.8%. Meningitis accounted for three of the four deaths identified and poor outcome was identified in 28% of cases of meningitis. We conclude that invasive pneumococcal disease causes significant morbidity and mortality in young Jamaican children. Strategies directed at preventing HIV infection and malnutrition and improving the care of children with sickle cell disease and HIV infection would significantly reduce disease incidence.

Serotypeº1 [corrected] childhood invasive pneumococcal disease has unique characteristics compared to disease caused by other streptococcus pneumoniae serotypes

BACKGROUND

We aimed to determine whether serotype 1 (SP1) invasive pneumococcal disease (IPD) can be distinguished by demographic, clinical and laboratory characteristics from IPD caused by the other most common serotypes (MCS) in our region: 5, 14, 6A, 6B, 19A, 19F, 23F.

METHODS

Data for all IPD episodes in children <18 years old treated at the Soroka University Medical Center during 2000 to 2009 were retrospectively retrieved. Episodes caused by SP1-IPD were compared with those caused by MCS-IPD (both grouped and individual serotypes). Analyses were adjusted for age and ethnicity.

RESULTS

Ninety-four SP1-IPD and 250 MCS-IPD episodes were documented. SP1-IPD cases were older (68.3 ± 52.6 months versus 30.4 ± 39.2 months; P < 0.001) and more likely to be found in Bedouin children than MCS-IPD (87.5% versus 58.6%; P < 0.001). SP1 was less frequently isolated from patients with underlying disease than MCS (14.9% versus 31.6 %; P < 0.001; relative risk 0.15 [95% confidence interval: 0.07-0.32]). SP1 was more often associated with bacteremic pneumonia and primary peritonitis than MCS (66% versus 38.4% and 7.4% versus 0.8%, respectively; P < 0.001); the proportion of bacteremia without focus was higher in MCS-IPD (32.4% versus 12.5%; P < 0.001). There were no differences in hospitalization and mortality rates (70.2% versus 68.0% [P = 0.22] and 4.3% versus 5.6% [P = 0.26], respectively).

CONCLUSIONS

SP1 was found less frequently than MCS in children with underlying diseases, but it was more frequent in older and Bedouin children with IPD. SP1 was more frequently associated with bacteremic pneumonia and primary peritonitis than MCS grouped.

Population biology of Streptococcus pneumoniae in West Africa: multilocus sequence typing of serotypes that exhibit different predisposition to invasive disease and carriage

Background

Little is known about the population biology of Streptococcus pneumoniae in developing countries, although the majority of pneumococcal infections occur in this setting. The aim of the study was to apply MLST to investigate the population biology of S. pneumoniae in West Africa.

Methods

Seventy three invasive and carriage S. pneumoniae isolates from three West African countries including The Gambia, Nigeria and Ghana were investigated. The isolates covered seven serotypes (1, 3, 5, 6A, 11, 14, 23F) and were subjected to multilocus sequence typing and antibiotic susceptibility testing.

Results

Overall, 50 different sequence types (STs) were identified, of which 38% (29) were novel. The most common ST was a novel clone-ST 4012 (6.5%), and some clones including STs 913, 925, 1737, 2160 and 3310 appeared to be specific to the study region. Two STs including ST 63 and ST 4012 were associated with multiple serotypes indicating a history of serotype switching. ST 63 was associated with serotypes 3 and 23F, while ST 4012 was associated with serotypes 6A and 23. eBURST analyses using the stringent 6/7 identical loci definition grouped the 50 STs into 5 clonal complexes and 65 singletons, expressing a high level of genetic diversity among the isolates. Compared to the other serotypes, serotypes 1 and 5 isolates appeared to be more clonal. Internationally recognized antibiotic resistant clones of S. pneumoniae were generally absent in the population investigated and the only multidrug resistant isolate identified (1/66) belong to the Pneumocococcal Epidemiology Network clone ST 63.

Conclusions

The pneumococcal population in West Africa is quite divergent, and serotypes that are common in invasive disease (such as serotypes 1 and 5) are more likely to be clonal than serotypes that are common in carriage.

Rapid reduction in invasive pneumococcal disease after introduction of PCV7 into the National Immunization Plan in Israel

BACKGROUND

The 7-valent conjugated vaccine (PCV7) was introduced into the Israeli National Immunization Program (NIP) in July 2009 (2, 4, 12 months schedule; 2 dose catch-up in second year of life). Nationwide active prospective surveillance on invasive pneumococcal disease (IPD) has been conducted in children since 1989. In the current study, IPD epidemiology in children <5 years during the 20 years before and 18 months after PCV7 NIP initiation, is reported.

METHODS

All 27 centers performing blood/cerebrospinal fluid (CSF) cultures in children reported monthly IPD cases. Capture-recapture approach was used for completeness.

RESULTS

During 1989-2010, 6022 IPD cases were reported in children <5 years; PCV7 serotypes (7VST) caused ∼50% of all episodes. In 2009 and 2010, 7VST IPD incidences <5 years of age (per 100,000) were 15.9 and 5.4, respectively (a 43% and 81% decrease, respectively) compared to 2003-2007 (mean incidence 27.8). Serotype 6A dynamics resembled those of 7VST. The respective overall IPD incidence decreases were 23% and 42%. The incidence dynamics of serotypes 1, 3, 5, 7F and 19A IPD were characterized by considerable fluctuations over the study period without any upwards or downwards trend in any of the age groups. The overall incidence of serotypes not included in the 13-valent pneumococcal conjugate vaccine (PCV13) did not vary significantly during the study period. By the end of 2010, 72% of the remaining IPD was caused by pneumococcal serotypes included in PCV13.

CONCLUSIONS

An active prospective long-term surveillance, showed a rapid and sharp decline in IPD in children <5 years following initiation of NIP with PCV7. No serotype replacement has been observed so far. The transition from PCV7 to PCV13 initiated in October 2010 may lead to a further substantial decrease in IPD. Follow-up is needed to better determine the long-term PCV effects.

Epidemic of invasive pneumococcal disease, western Canada, 2005-2009

In Canada before 2005, large outbreaks of pneumococcal disease, including invasive pneumococcal disease caused by serotype 5, were rare. Since then, an epidemic of serotype 5 invasive pneumococcal disease was reported: 52 cases during 2005, 393 during 2006, 457 during 2007, 104 during 2008, and 42 during in 2009. Of these 1,048 cases, 1,043 (99.5%) occurred in the western provinces of Canada. Median patient age was 41 years, and most (659 [59.3%]) patients were male. Most frequently representing serotype 5 cases (compared with a subset of persons with non-serotype 5 cases) were persons who were of First Nations heritage or homeless. Restriction fragment-length polymorphism typing indicated that the epidemic was caused by a single clone, which multilocus sequence typing identified as sequence type 289. Large pneumococcal epidemics might go unrecognized without surveillance programs to document fluctuations in serotype prevalence.

Epidemiology of invasive Kingella kingae infections in 2 distinct pediatric populations cohabiting in one geographic area

The annual incidence of invasive Kingella kingae infection in children younger than 4 years of age was significantly higher in westernized Jews than in indigent Bedouins living side by side in southern Israel (12.21/100,000 and 5.83/100,000, respectively, (P < 0.05). One K. kingae clone was overrepresented among isolates from Jewish children, suggesting that differences in bacterial pathogenicity may contribute to the morbidity excess detected in this population group.

Dynamics of pneumococcal nasopharyngeal carriage in healthy children attending a day care center in northern Spain. Influence of detection techniques on the results

BACKGROUND

Pneumococcal nasopharyngeal carriage precedes invasive infection and is the source for dissemination of the disease. Differences in sampling methodology, isolation or identification techniques, as well as the period (pre -or post-vaccination) when the study was performed, can influence the reported rates of colonization and the distribution of serotypes carried.

OBJECTIVES

To evaluate the prevalence and dynamics of pneumococcal nasopharyngeal colonization in healthy children aged 6-34 months attending a day care center with a high level of hygiene and no overcrowding. The study was performed 3-4 years after the 7-valent pneumococcal vaccine was introduced, using multiple methodologies to detect and characterize the isolates.

METHODS

Over 12 months, 25 children were sampled three times, 53 children twice and 27 children once. Three Streptococcus pneumoniae typing techniques were used: Quellung, Pneumotest-Latex-kit and multiplex-polymerase chain reaction (PCR). The similarity of isolates of the same serotype was established by pulsed field gel electrophoresis (PFGE) and occasionally the multilocus sequence type (ST) was also determined.

RESULTS

Overall pneumococcal carriage and multiple colonization rates were 89.5% (94/105) and 39%, respectively. Among 218 pneumococci detected, 21 different serotypes and 13 non-typeable isolates were found. The most prevalent serotypes were 19A, 16F and 15B. Serotypes 15B, 19A and 21 were mainly found as single carriage; in contrast serotypes 6B, 11A and 20, as well as infrequent serotypes, were isolated mainly as part of multiple carriage. Most 19A isolates were ST193 but most serotypes showed high genetic heterogeneity. Changes in the pneumococci colonizing each child were frequent and the same serotype detected on two occasions frequently showed a different genotype. By multiplex-PCR, 100% of pneumococci could be detected and 94% could be serotyped versus 80.3% by the Quellung reaction and Pneumotest-Latex in combination (p < 0.001).

CONCLUSIONS

Rates of S. pneumoniae carriage and multiple colonization were very high. Prevalent serotypes differed from those found in similar studies in the pre-vaccination period. In the same child, clearance of a pneumococcal strain and acquisition of a new one was frequent in a short period of time. The most effective technique for detecting pneumococcal nasopharyngeal carriers was multiplex-PCR.

Epidemiologic, clinical, laboratory, and therapeutic characteristics of influenza A/H1N1 in Moslem Bedouin and Jewish children hospitalized in southern Israel during 2009

A total of 739 (225 H1N1(+)) children with a diagnosis of acute respiratory infection were hospitalized during July to December 2009. The H1N1(+) children were compared with 225 randomly enrolled H1N1(-) children with an influenza-like illness. As compared with influenza-like illness patients, patients with 2009 influenza A/H1N1 were characterized by older age, more vomiting, less hypoxemia and wheezing, lower white blood cell counts, less neutrophilia, and severe lymphopenia.

Serotype distribution and drug resistance in Streptococcus pneumoniae, Palestinian Territories

To determine antimicrobial drug resistance of Streptococcus pneumoniae serotypes, we analyzed isolates from blood cultures of sick children residing in the West Bank before initiation of pneumococcal vaccination. Of 120 serotypes isolated, 50.8%, 73.3%, and 80.8% of the bacteremia cases could have been prevented by pneumococcal conjugate vaccines. Serotype 14 was the most drug-resistant serotype isolated.

Distribution, dynamics and antibiotic resistance patterns of Streptococcus pneumoniae serotypes causing acute otitis media in children in southern Israel during the 10 year-period before the introduction of the 7-valent pneumococcal conjugate vaccine

OBJECTIVES

To determine the dynamics of serotype prevalence, potential coverage by pneumococcal conjugate vaccines (PCV) and antibiotic resistance patterns of Streptococcus pneumoniae causing acute otitis media (AOM) in children in southern Israel before PCV7 introduction in the routine immunization program in Israel.

METHODS

All S. pneumoniae isolates from middle ear fluid from children with AOM during 1999-2008 were included. Prospectively collected demographic data on S. pneumoniae serotypes and antibiotic resistance patterns were analyzed.

RESULTS

A total of 14,911 tympanocenteses yielded 5281 (35%) S. pneumoniae. Proportion of S. pneumoniae-AOM did not vary significantly (overall 35%; 33% in 2007; 38% in 2002 and 2003). The most frequent serotypes were 19F, 14, 23F and 19A; in both Jewish and Bedouin children; serotypes 6A and 19A contributed 6% and 10%, respectively, of all S. pneumoniae isolates. Serotypes included in PCV7, PCV10 and PCV13 represented 60%, 64%, 85% in Jewish children vs. 49%, 55% and 74%, respectively, in Bedouin children (P < 0.001). Nonsusceptibility to TMP/SMX decreased significantly, in parallel with a significant increase in the nonsusceptibility to erythromycin, clindamycin and in multidrug resistant (MDR) isolates. No changes were recorded in the proportion of S. pneumoniae isolates with penicillin MIC ≥ 1.0 μg/ml. The proportion of penicillin- and erythromycin-nonsusceptible and of MDR serotype 6A and 19A isolates increased significantly in Bedouin children.

CONCLUSIONS

(1) No significant changes were recorded in the yearly proportions of serotypes 23F, 19F, 19A, 14 and 6A in both ethnic populations; (2) Potential coverage of the 3 PCVs was higher in Jewish children than in Bedouin children; (3) The relatively high coverage of macrolides- and multidrug-resistant S. pneumoniae by PCV13 and lack of increase in penicillin, erythromycin and multidrug nonsusceptibility among non-PCV13 isolates is encouraging.

Nasopharyngeal carriage of individual Streptococcus pneumoniae serotypes during pediatric pneumonia as a means to estimate serotype disease potential

BACKGROUND

We aimed at estimating pneumococcal serotype-specific disease potential in pediatric community-acquired alveolar pneumonia (CAAP), by comparing nasopharyngeal pneumococcal carriage during disease to carriage in healthy children.

METHODS

Pneumococcal nasopharyngeal cultures were obtained from children < 5 years old admitted to the emergency room or hospitalized with radiologically diagnosed CAAP and from healthy controls. Disease potential was estimated by calculating serotype-specific odds ratios (OR) of a given serotype to be carried during disease compared with healthy children (after adjustment for age, ethnicity, previous antibiotic therapy, and season).

RESULTS

A total of 603 and 1504 isolates were obtained from CAAP and healthy children, respectively. A significant OR > 1.0 of a specific serotype being carried during disease (suggesting a higher disease potential) was observed with serotypes (by decreasing rank) 1, 5, 22F, 7F, 14, 9V, and 19A. A significant OR < 1.0 of being carried during disease (suggesting a lower disease potential) was observed with serotypes 6A, 6B, 23A, and 35B. Carriage of PCV7 serotypes (grouped) during CAAP was highest in age group 6 to 17 months. PCV10 and PCV13 provided significantly higher coverage for both 6 to 17 and 18 to 35 month age groups.

CONCLUSIONS

It is suggested that serotypes 1, 5, 7F, 9V, 14, 19A, and 22F have a higher disease potential for childhood pneumonia than do serotypes 6A, 6B, 23A, and 35B.

Community-acquired bloodstream infections in children > one month old in southern Israel (1992–2001): Epidemiological, clinical and microbiological aspects

We studied the epidemiology, microbiology, clinical picture and outcome of community-acquired bloodstream infections (CABI) in children in southern Israel during 1992-2001. Information was collected prospectively by daily surveillance. CABI was diagnosed when a positive blood culture was reported in a patient discharged from the emergency room or during <48 h since admission if hospitalized. There were 1439 CABI episodes in 1396 children aged 1 month to 14 y. CABI incidence was 100/100,000 children with no increase during the study period. Risk of CABI was 3.8 times higher in a Bedouin than in a Jewish child. 1561 bacteria (793, 50%, gram-positive and 768, 49% gram-negative organisms, respectively) and 13 fungi were recovered. Most frequent gram-positive organisms were Streptococcus pneumoniae (509 isolates, 32% of all isolates, 64% of all gram-positive), Staphylococcus aureus (137, 9%, 17%) and Streptococcus pyogenes (46, 3%, 6%). Enterobacteriaceae spp. were the most frequent gram-negative pathogens (279, 18%, 36%), followed by Brucella (205, 13%, 27%). S. pneumoniae was the most common pathogen in children <12 months and 1-5 y age; Brucella was the most frequent pathogen in children >5 y of age. Coverage of 7-valent pneumococcal conjugated vaccine for CABI was 38.5%. 38 (2.7%) patients died; 16 cases were caused by S. pneumoniae.

Complicated community acquired pneumonia in children prior to the introduction of the pneumococcal conjugated vaccine

Increasing prevalence of pleural empyema (PE) complicating community acquired pneumonia (CAP) is reported worldwide. We compared hospitalized children with PE or non-purulent pleural effusion (NP-PEF) prior to the inclusion of the pneumococcal conjugated vaccine (PCV7) in the Israeli immunization schedule. We conducted a retrospective analysis of medical files of all children <18 y of age hospitalized with either PE or NP-PEF and CAP during 1990-2002. 75 children with NP-PEF and 37 with PE were identified. PE annual incidence increased from 0.5 in 1990 to 4.2 per 100,000 children in 2002. Higher WBC and absolute neutrophils counts were found in sera and pleural fluid of PE. The leading pathogens included Streptococcus pneumoniae (42%, all penicillin-susceptible) and Staphylococcus aureus (23%, all methicillin-susceptible). Blood cultures were positive only in children with PE (12/37, 32.4%). Patients with PE presented with higher respiratory rate and required longer hospitalization, more PICU admission, and more patients needed mechanical ventilation. PE prevalence increased in southern Israel during the study period. Streptococcus pneumoniae (62.5% serotype 1) was the most common pathogen causing PE before the introduction of PCV7. Future introduction of PCV7 or equivalents in the immunization schedule may impact clinical presentation and epidemic trends and will require future consideration.

Serotype coverage of invasive and mucosal pneumococcal disease in Israeli children younger than 3 years by various pneumococcal conjugate vaccines

BACKGROUND

: Since the introduction of the 7-valent pneumococcal conjugate vaccine (PCV7) in the United States, the need for additional serotype coverage has become clear. Our objective was to assess the potential serotype coverage of PCV7 and of the 2 experimental conjugate vaccines, 10-valent (PCV10) and 13-valent (PCV13), against invasive pneumococcal disease (IPD), acute otitis media (AOM), acute conjunctivitis (AC), and pneumococcal carriage in southern Israel, where PCV7 had not yet been introduced at the time of the study.

METHODS

: Data on isolates were obtained prospectively from children <36 months during 2000-2004. The potential coverage of the PCVs was calculated and analyzed separately for antibiotic-resistant strains.

RESULTS

: A total of 5497 isolates were collected: 189 from blood or cerebrospinal fluid, 3197 from middle ear fluid, 348 from the conjunctiva, and 1763 from the nasopharynx of healthy children. The serotype coverage of PCV7 for IPD, AOM, AC, and carriage was 44%, 54%, 37%, and 46%, respectively. Serotypes included in PCV7 caused 47 IPD cases per 100,000 children <3 years (54 per 100,000 if serotype 6A is included). PCV10 extended mainly the coverage of IPD, while addition of serotypes 6A and 19A to PCV13 increased the coverage substantially in all entities (84%, 79%, 54%, and 67% in IPD, AOM, AC, and carriage, respectively). PCV13 could prevent >90% of penicillin-, macrolide-, and multidrug-resistant strains associated with IPD and AOM.

CONCLUSIONS

: PCV7 can substantially decrease pneumococcal disease and carriage in Israel, but PCV10 and PCV13 have a significant added benefit. Moreover, PCV13 has an important potential added benefit over PCV7 and PCV10 in reducing disease by drug-resistant Streptococcus pneumoniae.

The association between antibiotic use in the community and nasopharyngeal carriage of antibiotic-resistant Streptococcus pneumoniae in Bedouin children

BACKGROUND

The objective of the study was to evaluate whether the increase in antibiotic-resistant Streptococcus pneumoniae carriage was associated with antibiotic use in the community in children in Southern Israel.

METHODS

All the prescriptions given to Bedouin children <5 years old enlisted in 2 sentinel primary pediatric clinics treating approximately 20% of the Bedouin pediatric population of this age range were recorded, from 1998 to 2005. Nasopharyngeal pneumococcal isolates obtained during the same period from healthy children <5 years old were collected and antibiotic susceptibility was determined.

RESULTS

A total of 1488 of 1927 (77.7%) cultures were positive for S. pneumoniae. The proportion of S. pneumoniae with penicillin minimal inhibitory concentration > or = 1.0 microg/mL increased from 8% to 21% (P < 0.01); resistance to clindamycin from 9% to 22%; resistance to erythromycin from 13% to 30%; resistance to tetracycline from 13% to 31%; and multidrug resistance from 16% to 30%. The total annual antibiotic prescription rates decreased by 19%, from 3867 to 3191 prescriptions per 1000 children (P < 0.001). This was mainly the result of a reduction in amoxicillin +/- clavulanate prescriptions (from 3046 to 2582; P < 0.001). Oral cephalosporin, erythromycin and penicillin prescription rates decreased significantly as well (P < 0.001) whereas azithromycin prescription rates increased significantly (P < 0.001).

CONCLUSIONS

We suggest that the increased carriage of S. pneumoniae resistant to multiple antibiotics is possibly associated to the increased azithromycin consumption. Reduction of total antibiotic use may not be sufficient as long as antibiotics with high potential to promote multidrug resistance, given their pharmacokinetics and pharmacodynamics characteristics, are widely used.

International Circumpolar Surveillance System for invasive pneumococcal disease, 1999-2005

The International Circumpolar Surveillance System is a population-based surveillance network for invasive bacterial disease in the Arctic. The 7-valent pneumococcal conjugate vaccine (PCV7) was introduced for routine infant vaccination in Alaska (2001), northern Canada (2002-2006), and Norway (2006). Data for invasive pneumococcal disease (IPD) were analyzed to identify clinical findings, disease rates, serotype distribution, and antimicrobial drug susceptibility; 11,244 IPD cases were reported. Pneumonia and bacteremia were common clinical findings. Rates of IPD among indigenous persons in Alaska and northern Canada were 43 and 38 cases per 100,000 population, respectively. Rates in children <2 years of age ranged from 21 to 153 cases per 100,000 population. In Alaska and northern Canada, IPD rates in children <2 years of age caused by PCV7 serotypes decreased by >80% after routine vaccination. IPD rates are high among indigenous persons and children in Arctic countries. After vaccine introduction, IPD caused by non-PCV7 serotypes increased in Alaska.

Contributions of Native Americans to the global control of infectious diseases

For over a half of a century, Native American populations have participated in numerous studies regarding the epidemiology, prevention and treatment of infectious diseases. These studies have resulted in measures to prevent morbidity and mortality from many infectious diseases. The lessons learned from these studies and their resultant prevention or treatment interventions have been applied around the world, and have had a major impact in the reduction of global childhood morbidity and mortality.

Epidemiologic features of invasive pneumococcal disease in Belgian children: passive surveillance is not enough

BACKGROUND

Reliable epidemiologic surveillance of infectious diseases is important for making rational choices for public health issues such as vaccination strategies. In Belgium, as in most European countries, surveillance relies on voluntary passive reporting from microbiology laboratories; therefore, reported incidence rates are probably inaccurate.

METHODS

We conducted national, active, laboratory-based and clinically based surveillance of invasive pneumococcal disease in young children.

RESULTS

During the study period, the incidences of invasive pneumococcal disease in children < 2 years of age (104.4 cases per 10(5) person-years and 16.1 cases per 10(5) person-years for invasive pneumococcal disease and meningitis, respectively) and in children 0 to 59 months of age (59.5 cases per 10(5) person-years for invasive pneumococcal disease and 7.7 cases per 10(5) person-years for meningitis) were twice those reported previously through the passive surveillance system. Overall, 67% of the Streptococcus pneumoniae strains isolated from children < 5 years of age belonged to 7-valent pneumococcal conjugate vaccine serotypes and 18% to vaccine-related serotypes (mainly serotype 19A). Erythromycin resistance was frequent, especially among children < 2 years of age (59%).

CONCLUSIONS

Under-reporting can explain the reported low incidence of invasive pneumococcal disease in countries (such as Belgium) that depend on a passive epidemiologic surveillance system, which could lead to erroneous choices in vaccination policies. There is a need for an active system of epidemiologic surveillance for vaccine-preventable diseases such as invasive pneumococcal disease, at the national or European level.

Nutritional status and diarrheal illness as independent risk factors for alveolar pneumonia

Community-acquired alveolar pneumonia (CAAP) is typically associated with bacterial infections and is especially prevalent in vulnerable populations worldwide. The authors studied nutritional status and diarrheal history as risk factors for CAAP in Bedouin children <5 years of age living in Israel. In this prospective case-control study (2001-2002), 334 children with radiographically confirmed CAAP were compared with 529 controls without pneumonia with regard to nutritional status and diarrhea history. Controls were frequency matched to cases on age and enrollment month. Logistic regression models were used to evaluate associations of CAAP with nutritional status and recent diarrhea experience. Anemia (adjusted odds ratio (AOR) = 3.32, 95% confidence interval (CI): 2.24, 4.94; p < 0.001), low birth weight (AOR = 2.16, 95% CI: 1.32, 3.54; p = 0.002), stunting (AOR = 2.22, 95% CI: 1.31, 3.78; p = 0.004), serum retinol concentration (AOR = 1.03 per microg/dl, 95% CI: 1.02, 1.05; p < 0.001), and having > or =1 diarrhea episodes within 31 days prior to enrollment (AOR = 2.30, 95% CI: 1.26, 4.19; p = 0.007) were identified as risk factors for CAAP. Results suggest that improving antenatal care and the nutritional status of infants may reduce the risk of CAAP in Bedouin children. Furthermore, they suggest that vaccines developed to prevent diarrhea may also lower the risk of CAAP.

Temporal Trends of Invasive Disease Due to Streptococcus pneumoniae among Children in the Intermountain West: Emergence of Nonvaccine Serogroups

BACKGROUND

Use of the heptavalent pneumococcal conjugate vaccine (PCV-7 [Prevnar]) has been associated with decreased a incidence of invasive pneumococcal disease (IPD) among children in the United States.

METHODS

Cases of IPD in children < 18 years of age insured by or receiving health care from Intermountain Health Care during 1996-2003 were identified. Isolates of S. pneumoniae from children with IPD treated at Primary Children's Medical Center (PCMC; Salt Lake City, UT) during 1997-2003 were serogrouped. Temporal trends of IPD, serogroup distribution of pneumococci, and antibiotic resistance among pneumococci were analyzed.

RESULTS

A total of 1535 cases of IPD were identified. The rate of IPD decreased 27% after the introduction of PCV7. Among children with IPD who were cared for at PCMC, disease in 73% was caused by PCV7 serogroups in 1997-2000, compared with 50% in 2001-2003 (P < .001), and the percentage of isolates resistant to penicillin decreased from 34% in 1997-2000 to 22% in 2001-2003 (P = .04). The percentage of IPD cases that were empyema increased from 16% to 30% (P = .015), and the percentage of severe cases of IPD increased from 57% to 71% (P = .026). Children with IPD due to non-PCV7 serogroups were older, were more likely to have parapneumonic empyema, and had longer hospital stays.

CONCLUSIONS

The incidence of IPD in the IMW decreased by 27% after the introduction of the PCV7 vaccine. During the postvaccine period (2001-2003), there were significant decreases in the proportion of cases of IPD caused by PCV7 and antibiotic-resistant serogroups. These benefits were accompanied by a significant increase in the proportion of IPD cases due to non-PCV7 serogroups, with increases in the incidence of empyema and severe IPD.

Streptococcus pneumoniae serotypes/serogroups causing invasive disease in Riyadh, Saudi Arabia: extent of coverage by pneumococcal vaccines

BACKGROUND

Serogroup distribution of sterile site pneumococcal isolates varies between developing and developed countries as well as between different geographical regions. The potential efficacy of any pneumococcal vaccine depends on the degree of representation of the prevalent serogroups in the vaccine. We conducted this study to determine the prevalent pneumococcal serogroups causing invasive infections in Riyadh, Saudi Arabia and to estimate the coverage by the various pneumococcal conjugate vaccines.

METHODS

S. pneumoniae isolated between February 2000 and November 2001 from sterile sites of patients of all age groups were collected from 8 major hospitals in Riyadh and serogrouped using the latex agglutination method.

RESULTS

Isolates from 78 patients, 72% of whom were children, were studied. Eighty-eight percent of the isolates belonged to only 10 serogroups/serotypes, namely 6 and 19, 1 and 15, 14 and 23, 7, 18 and 22, in descending order of frequency. Potential coverage of the 7-valent, 9-valent, and 11-valent conjugate vaccines were 54%, 65% and 73%, respectively. The rate of reduced penicillin susceptibility in the serogroups represented in the 7-valent conjugate vaccine was significantly higher than in the non-vaccine serogroups (62% vs. 25%; P=0.0023).

CONCLUSION

The currently available 7-valent pneumococcal conjugate vaccine provides sub-optimal coverage to serogroups causing invasive diseases in our community. However, this vaccine would be a useful adjunct to penicillin prophylaxis in at-risk patients in the community. The effectiveness of the vaccine would be greater if serotype 15 could be included.

Advances in Pneumococcal Vaccines

The introduction of Haemophilus influenzae type b (Hib) vaccine into the universal immunisation schedules of many industrialised countries and the subsequent remarkable decline in the incidence of invasive Hib disease has further highlighted the impact of invasive pneumococcal diseases. Streptococcus pneumoniae is now the leading cause of bacterial meningitis in children in many settings and a leading cause of vaccine-preventable bacterial disease in children worldwide. The currently marketed 23-valent pneumococcal polysaccharide vaccine provides large serotype coverage at a relatively low cost. However, it is not efficacious in young children. Pneumococcal conjugate vaccines (PCVs) are highly effective in preventing invasive disease in infants and young children, with favourable safety and immunogenicity profiles. These vaccines have also shown efficacy in reducing cases of non-invasive disease (i.e. otitis media), nasopharyngeal acquisition of vaccine-specific serotypes of S. pneumoniae, and protection against pneumococcal disease caused by resistant strains. However, PCV contains a limited number of pneumococcal serotypes and, given adequate ecological pressure, replacement disease by non-vaccine serotypes remains a threat, particularly in areas with very high disease burden. Furthermore, although capsular-specific antibodies have been shown to be highly protective, it remains unclear what concentration of these serotype-specific antibodies protect against disease and, more recently, it has become clear that opsonic activity and avidity of these antibodies are more critical determinants of protection than concentration. Therefore, monitoring disease burden and defining immune correlates of protection after widespread use of conjugate vaccines are crucial for the evaluation of these new generation vaccines. Furthermore, a need exists to develop pneumococcal vaccines with lower cost and larger serotype coverage. Development of one or more protein vaccines that might be easier and, thus, less expensive to manufacture, and which might provide protection against multiple serotypes, is in progress. This article reviews the current state of pneumococcal disease and pneumococcal vaccines in clinical use.

Streptococcus pneumoniae in nasopharyngeal secretions of healthy children: comparison of real-time PCR and culture from STGG-transport medium

Precise methods for the detection of Streptococcus pneumoniae are needed for predicting the consequences of pneumococcal conjugate vaccines on nasopharyngeal carriage. In this study, 400 nasopharyngeal swab samples from children were analyzed using a real-time pneumolysin (ply)-PCR method. The specimens were originally collected into STGG-transport medium and cultured in 1999, after which they were stored at -80 degrees C until analyzed by real-time PCR in 2001. The sensitivities of real-time PCR and culture methods were also studied by analyzing 10-fold dilutions of a pneumococcal broth culture using both methods. Of the 400 nasopharyngeal swab samples, 158 (40%) were positive in culture and 276 (69%) by real-time PCR. A minor part (4%) of the culture-positive samples remained negative by PCR. There was a trend between the quantity of genome equivalents detected by PCR and the number of colonies found in culture. When analyzing 10-fold dilutions of a pneumococcal broth culture, a higher number of genome equivalents were detected using real-time PCR than the number of colonies detected by culture. Quantitative real-time PCR provides feasible means for quantifying pneumococcal carriage. Further studies are needed to confirm that positive PCR findings really indicate the presence of viable pneumococcus in nasopharyngeal specimens.

Twenty year surveillance of invasive pneumococcal disease in Nottingham: serogroups responsible and implications for immunisation

AIMS

To evaluate the incidence, spectrum of clinical manifestations, and outcome of invasive pneumococcal disease (IPD) in children. To determine the major serogroups of Streptococcus pneumoniae responsible for invasive disease and the potential coverage by the new pneumococcal conjugate vaccines.

METHODS

Analysis of prospectively recorded information of all children admitted to two teaching hospitals in Nottingham with IPD between January 1980 and December 1999.

RESULTS

A total of 266 episodes of IPD in children were identified; 103 (39%) were aged <1 year and 160 (60%) <2 years. Major clinical presentations were meningitis in 86 (32%), pneumonia in 82 (31%), and bacteraemia without an obvious focus in 80 (30%). The age specific mean annual incidence rates of IPD overall among children aged <1, <2, and <5 years were 47.1, 37.8, and 20 per 100 000 population, respectively. Mortality rates for children with meningitis and non-meningitic infection were 20% and 7%, respectively. Neurological sequelae following meningitis were documented in 16 (26%) of the 61 survivors assessed. The potential coverage rates in children between the ages of 6 months and 5 years are 84% by the 7-valent, 91% by the 9-valent, and 95% by the 11-valent conjugate vaccines.

CONCLUSION

This study indicates that inclusion of a pneumococcal conjugate vaccine in the primary immunisation programme in the UK would have a considerable effect on the mortality and morbidity associated with IPD.

Antibiotic-resistant invasive pediatric Streptococcus pneumoniae clones in Israel

Antibiotic-resistant international clones of Streptococcus pneumoniae are increasingly reported in different parts of the world. We investigated the spread of these clones through an active surveillance performed at the Israeli Streptococcal National Center during 1998 and 1999. Isolates were tested for antibiotic susceptibility, serotyped, and genotyped by random amplified polymorphic DNA analysis and pulsed-field gel electrophoresis. Of 437 isolates, 276 (63.4%) were antibiotic resistant and 156 (35%) were penicillin nonsusceptible (PNS). The PNS isolates were less frequently encountered in southern Israel (27 of 136 [20%]) than in other regions (127 of 301 [42%]). Among 276 antibiotic-resistant isolates, 43 fingerprint patterns were observed. The most common clones were 9V/14-a (19.2%), 5-a (17.8%), and 1-a (10%). The 9V/14-a clone was less common, while the 1-a clone was more frequent in the south than in other regions. The 5-a clone was more common in Jerusalem than in other regions. Among the Jewish and Arab populations the most frequent clones were 9V/14-a (20%) and 1-a (25%), respectively. Three international clones, 9V/14-a-Spain(9V)-3, 6B-a-Spain(6B)-2, and 5-a-Colombia(5)-19, comprised 40% of all antibiotic-resistant isolates and 56% of all PNS isolates. The seven-valent conjugate vaccine covers 58% of the most common clones, all highly PNS clones, and 94% of the multidrug-resistant clones in Israel, while the nine-valent vaccine covers all of them. The most common antibiotic-resistant invasive pediatric S. pneumoniae clones-mainly the three international ones-contribute significantly to increases in antibiotic resistance. Their geographic distribution varies within the country and between the different populations.

Tolerability and immunogenicity of an eleven valent mixed carrier Streptococcus pneumoniae capsular polysaccharide-diphtheria toxoid or tetanus protein conjugate vaccine in Finnish and Israeli infants

BACKGROUND

To have wide global coverage of pneumococcal serotypes, the number of serotypes covered by the current 7-valent pneumococcal conjugate vaccine must be increased. We have studied the safety and immunogenicity of an 11-valent mixed carrier vaccine (PncDT11) in infants.

METHODS

The study vaccine contained polysaccharide antigens of serotypes 1, 4, 5, 7F, 9V, 19F and 23F conjugated to tetanus protein and serotypes 3, 6B, 14 and 18C conjugated to diphtheria toxoid. The vaccine was administered to Finnish (n = 117) and Israeli (n = 135) infants at ages 2, 4, 6 and 12 months concomitantly with other vaccines used in national vaccination programs. IgG antibodies to polysaccharides were determined by enzyme immunoassay from serum samples taken at ages 2, 7, 12 and 13 months. After each injection the infants were followed for 30 min to detect any immediate adverse reactions, and parents were given a diary card to report any adverse events during the next 5 days.

RESULTS

No severe adverse reactions occurred, and immediate adverse reactions were rare. After each dose approximately 30% of the vaccinees experienced local reactions of which pain was the most common. Fever of >38 degrees C was reported in 33 to 53% of the vaccinees and high fever (>40 degrees C) was reported 6 times. The PncDT11 vaccine was immunogenic. The antibody concentrations after primary immunization series were higher in Israeli than in Finnish infants, but the differences were not significant for most serotypes. The difference was most marked at 13 months, a time point at which the difference was significant in 10 of 11 serotypes.

CONCLUSION

PncDT11 is safe and immunogenic in infants. The use of 11-valent pneumococcal vaccine would increase the serotype coverage beyond the currently available 7-valent vaccine.

Geographic distribution and clonal diversity of Streptococcus pneumoniae serotype 1 isolates

Serotype 1 pneumococci are a major cause of serious disease and have been associated with outbreaks but are rarely carried. The high attack rate and lack of coverage of this serotype by the heptavalent conjugate vaccine prompted the characterization of a geographically diverse collection of 166 serotype 1 isolates from recent cases of invasive disease. The isolates were resolved by multilocus sequence typing into 16 clones, which clustered into three major lineages with very different geographic distributions. Lineage A isolates were exclusively from Europe and North America, lineage B isolates were predominantly from Africa and Israel, and lineage C isolates were mainly from Chile. There was no clear association between the presence of individual clones within a country and the prevalence of serotype 1 disease.

Interleukin-12 receptor beta1 deficiency presenting as recurrent Salmonella infection

We describe a child with interleukin-12 receptor beta1 (IL-12Rbeta1) deficiency caused by a homozygous IL12RB1 large deletion who presented at the age of 1 year with recurrent, often asymptomatic episodes of bacteremia caused by group D Salmonella species. No mycobacterial disease or other unusual infection was present. The episodes of salmonellosis were caused by an identical serovar during a period of 18 months. This is the first case of inherited IL-12Rbeta1 deficiency diagnosed after isolated, recurrent salmonellosis.

Population-based surveillance for hospitalized and ambulatory pediatric invasive pneumococcal disease in Santiago, Chile

BACKGROUND

Nine- and 11-valent pneumococcal conjugate vaccines under development may control pediatric pneumococcal disease in nonindustrialized countries. Because these vaccines are expensive, population-based surveillance of pneumococcal disease in children <36 months of age was undertaken in Santiago, Chile to provide health authorities with reliable data on the burden of invasive pneumococcal disease and causative serotypes, including those in outpatients with high fever.

METHODS

Automated blood culture machines were introduced into 9 hospitals that admit 85% of all hospitalized children in Santiago. Acutely ill pediatric febrile ambulatory patients are attended at 8 emergency rooms (ERs) and 36 urgent primary care services. After a 12-month pilot study in 3 ERs, health authorities collected blood cultures from children <36 months of age with high fever seen in the ER as standard practice. isolates were serotyped.

RESULTS

Blood cultures of 18 (1.2%) of 1,503 outpatients 6 to 35 months of age with high fever in the pilot study yielded S. In the ensuing 24 months 236 children <36 months old were hospitalized with invasive pneumococcal disease (incidence, 33.9 cases/10(5) children), and 188 bacteremias were detected among ambulatory ER patients with high fever (incidence, 27.0 cases/10(5) children). Although serotypes were similar among hospitalized and ambulatory cases (except 18C, which was more common in the latter), case fatality was 9.5% in hospitalized (21 of 236) 0% in ambulatory cases (0 of 188) (P = <0.0001). High level resistance to penicillin (25.8% vs 10.1%) and cefotaxime (19.5% vs 6.2%) was observed more often among pneumococcal isolates from hospitalized than among ambulatory cases (P < 0.001).

CONCLUSIONS

ER surveillance detected approximately one case of pneumococcal bacteremia among febrile ambulatory patients for each hospitalized invasive case. Because 71% of cases were caused by vaccine serotypes (and 87% by vaccine serogroups), 9- and 11-valent pneumococcal conjugate vaccines could prevent most invasive pediatric pneumococcal disease in Chile.