Invasive pneumococcal disease in Australia, 2004

There were 2,375 cases of invasive pneumococcal disease (IPD) notified to the National Notifiable Diseases Surveillance System in Australia in 2004; a notification rate of 11.8 cases per 100,000 population. The rate varied between states and territories and by geographical region with the highest rates in the Northern Territory. Invasive pneumococcal disease was reported most frequently in children aged less than 5 years (55.4 cases per 100,000 population). Enhanced surveillance for IPD was carried out in all states and territories, in 2004, providing additional data on 2,023 (85%) cases. The overall rate of IPD in Indigenous Australians was 3.2 times the rate in non-Indigenous Australians. There were 154 deaths attributed to IPD resulting in an overall case fatality rate of 7.6 per cent. Rates of IPD in the Indigenous and non-Indigenous under 2-year-old population were similar in 2004 (91.5 and 93.6 cases per 100,000 population, respectively) following a targeted introduction of the 7-valent pneumococcal conjugate vaccine (7vPCV) in mid-2001 for Indigenous infants and children. Serotypes of isolates were identified from 80 per cent of all notified cases, with 72 per cent of isolates belonging to serotypes represented in the 7vPCV and 91 per cent in the 23-valent polysaccharide pneumococcal vaccine (23vPPV). Comparison of serotypes in the 7vPCV target population showed that the rate of IPD due to 7vPCV serotypes decreased by 74 per cent between 2001-02 and 2003-04. Of 216 isolates with reduced penicillin susceptibility, 83 per cent belonged to pneumococcal serotypes in the 7vPCV and 95 per cent in the 23vPPV.     

Invasive pneumococcal disease in Australia, 2003.

There were 2,174 cases of invasive pneumococcal disease (IPD) notified to the National Notifiable Diseases Surveillance System (NNDSS) in Australia in 2003; a rate of 10.9 per 100,000 population. The notification rate varied between states and territories and by geographical region with the highest rates in the north of the country. Invasive pneumococcal disease was reported most frequently in children aged less than two years (98.8 cases per 100,000 population). Enhanced surveillance for IPD in 2003 was carried out in all states and territories, providing additional data on 1,842 (85%) of all notified cases. Rates of IPD in Indigenous Australians were three times the rate in non-Indigenous Australians. There were 125 deaths attributed to IPD resulting in an overall case fatality rate of 6.8 per cent. Seventy-one percent of all pneumococcal isolates serotyped were serotypes in the seven-valent conjugate vaccine and 91 per cent were serotypes in the 23-valent polysaccharide pneumococcal vaccine. The clinical presentation and risk factors for IPD varied between Indigenous and non-Indigenous cases and non-vaccine serotypes occurred more frequently among Indigenous children and adults. Data from three years of surveillance indicate an early impact of the 7-valent vaccine in the target population.     

Invasive pneumococcal disease in Australia, 2002.

There were 2,271 cases of invasive pneumococcal disease (IPD) notified to the National Notifiable Diseases Surveillance System in Australia in 2002; a rate of 11.5 cases per 100,000 population. The notification rate varied between states and territories and by geographical region with the highest rates in the north of the country. Invasive pneumococcal disease was reported most frequently in children aged less than five years (57.3 per 100,000 population). Enhanced surveillance for IPD in 2002 was carried out in all states and territories, providing additional data on 1,929 (85%) of all notified cases. Rates of IPD in Indigenous Australians were 2.7 times the rate in non-Indigenous Australians. The clinical presentation of IPD was most commonly pneumonia (44%) and bacteraemia (35%). There were 175 deaths attributed to IPD resulting in an overall case fatality rate of 9.2 per cent. Forty-two per cent of all cases had a recognised risk factor for IPD. Seventy-five per cent of all pneumococcal isolates serotyped were serotypes in the seven-valent conjugate vaccine and 93 per cent were serotypes in the 23-valent polysaccharide pneumococcal vaccine. The clinical presentation and rates of risk factors varied between Indigenous and non-Indigenous cases and non-vaccine serotypes occurred more frequently among Indigenous children and adults.     

Invasive pneumococcal disease in Australia, 2005

Enhanced surveillance for invasive pneumococcal disease (IPD) was carried out in all Australian states and territories in 2005 with comparative data available since 2001. There were 1,680 cases of IPD notified to the National Notifiable Diseases Surveillance System in Australia in 2005; a notification rate of 8.3 cases per 100,000 population. The rates varied between states and territories and by geographical region with the highest rates in the Northern Territory, the jurisdiction with the largest proportion of Indigenous people. Invasive pneumococcal disease was reported most frequently in those aged 85 years or over (41 cases per 100,000 population) and in 1-year-old children (36.5 cases per 100,000 population). Enhanced data provided additional information on 1,015 (60%) of all notified cases. The overall rate of IPD in Indigenous Australians was 8.6 times the rate in non-Indigenous Australians. There were 126 deaths attributed to IPD resulting in an overall case fatality rate of 7.5%. While the rate of IPD in the Indigenous under 2-year-old population decreased from 219 cases per 100,000 population since targeted introduction of the 7-valent conjugate pneumococcal vaccine (7vPCV) in 2001, the rate in 2005 (94 cases per 100,000 population) was significantly greater than in non-Indigenous children (20.4 cases per 100,000 population). Rates of disease in all children aged less than 2 years, caused by serotypes in the 7vPCV decreased by 75% between 2004 and 2005 as a result of the introduction of a universal childhood 7vPCV immunisation program. Significant decreases in IPD caused by 7vPCV serotypes also occurred in the 2-14 years and 65 years or over age groups. There is no evidence of replacement disease with non-vaccine serotypes. Serotypes were identified in 90% of all notified cases, with 61% of disease caused by serotypes in the 7vPCV and 88% caused by serotypes in the 23-valent polysaccharide pneumococcal vaccine (23vPPV). Reduced penicillin susceptibility remains low and reduced susceptibility to 3rd generation cephalosporins is rare.     

Laboratory surveillance of invasive pneumococcal disease in Australia, 2003 predicting the future impact of the universal childhood conjugate vaccine program.

A comprehensive invasive pneumococcal disease (IPD) laboratory surveillance program was carried out in Australia in 2003. This program provided data on the prevalence of pneumococcal serotypes and antimicrobial resistance. There were 1,995 isolates tested with 34 per cent (683) from children aged less than five years and 27 per cent (535) from the elderly aged more than 65 years. One thousand eight hundred and sixty were isolates from blood, 79 from CSF and 56 from other sterile sites. In young children, 84 per cent of isolates were a serotype and 92 per cent a serogroup in the 7-valent pneumococcal conjugate vaccine (7vPCV). Of penicillin resistant isolates in children less than five years of age 85 per cent and 98 per cent were a serotype and serogroup in the 7vPCV respectively. When the universal 7vPCV vaccine program in young children is introduced in 2005, a proportion of cases of IPD should also be prevented in young adults (estimated reduction of 54 cases annually) and elderly Australians (an estimated reduction of 110 cases annually) as a result of improved herd immunity. Pneumococcal serotypes with higher rates of penicillin resistance (19F, 14 and 6B) were more prevalent in the elderly than in young children. In contrast, erythromycin resistance was more common in children less than five years of age (24%) compared to the elderly (15%). The predominant serotype with erythromycin resistance in Australia was serotype 14 and thus there is likely to be a major reduction in erythromycin resistance as a result of 7vPCV vaccination. Continued surveillance of pneumococcal serotype distribution and antibiotic susceptibility will be essential in order to identify serotype replacement by non-vaccine serotypes and to monitor the overall impact of current and future vaccine programs on invasive pneumococcal disease in Australia, not only in young children but also in other age groups.     

Invasive pneumococcal disease in Australia, 2006

Enhanced surveillance for invasive pneumococcal disease (IPD) was carried out in all Australian states and territories in 2006 with comprehensive comparative data available since 2002. There were 1,445 cases of IPD notified to the National Notifiable Diseases Surveillance System in Australia in 2006; a notification rate of 7 cases per 100,000 population. The rates varied between states and territories and by geographical region with the highest rates in the Northern Territory, the jurisdiction with the largest proportion of Indigenous people. Invasive pneumococcal disease was reported most frequently in those aged 85 years or over (30.8 cases per 100,000 population) and in children aged one year (26.5 cases per 100,000 population). There were 130 deaths attributed to IPD resulting in an overall case fatality rate of 9%. The overall rate of IPD in Indigenous Australians was 4.3 times the rate in non-indigenous Australians. The rate of IPD in the under two years population continued to fall in 2006, but the rate in Indigenous children (73 cases per 100,000 population) was significantly greater than in non-Indigenous children (21 cases per 100,000 population). The rates of disease caused by serotypes in the 7-valent pneumococcal conjugate vaccine (7vPCV) decreased between 2002 and 2006 by 78% in children aged under two years as a result of the introduction of a universal childhood 7vPCV immunisation program. Significant decreases in IPD caused by 7vPCV serotypes also occurred in the 2-14 years and 65 years or over age groups. Rates of disease caused by non-7vPCV in the same periods were little changed. Serotypes were identified in 94% of all notified cases, with 43% of disease caused by serotypes in the 7vPCV and 85% caused by serotypes in the 23-valent polysaccharide pneumococcal vaccine (23vPPV). The number of invasive pneumococcal isolates with reduced penicillin susceptibility remains low and reduced susceptibility to third generation cephalosporins is rare.     

The impact of the changing pneumococcal national immunisation program among older Australians

Australia has a universal infant pneumococcal conjugate vaccination program and until recently a universal pneumococcal polysaccharide vaccine program for non-Indigenous adults aged ≥65 years and Indigenous adults aged ≥50 years. We documented the impacts of infant and adult vaccination programs on the epidemiology of invasive pneumococcal disease (IPD) in Indigenous and non-Indigenous adults.IPD notifications from the National Notifiable Disease Surveillance System were analysed from 2002 to 2017, grouped by age, vaccine serotype group and Indigenous status. Since the universal funding of infant and elderly pneumococcal vaccination programs in January 2005, total IPD decreased by 19% in non-Indigenous adults aged ≥65 years but doubled in Indigenous adults aged ≥50 years. Vaccine uptake was suboptimal in both groups but lower in Indigenous adults. IPD due to the serotypes contained in the pneumococcal conjugate vaccines (PCV) except for serotype 3 declined markedly over the study period but were replaced by non-PCV serotypes. Serotype 3 is currently the most common in older adults. In the populations eligible for the adult 23-valent pneumococcal polysaccharide vaccine (23vPPV) program, IPD rates due to its exclusive serotypes increased to a lower extent than non-vaccine types. In 2017, non-vaccine serotypes accounted for most IPD in the older population eligible for the 23vPPV program, while it's eleven exclusive serotypes accounted for the majority of IPD in younger adults.Infant and adult pneumococcal vaccination programs in Australia have shaped the serotype-specific epidemiology of IPD in older adults. IPD remains a significant health burden for the Indigenous population. Herd immunity impact is clear for PCV serotypes excluding serotype 3 and serotype replacement is evident for non-PCV serotypes. The adult 23vPPV immunisation program appears to have partially curbed replacement with IPD due to its eleven exclusive serotypes, highlighting a potential benefit of increasing adult 23vPPV coverage in Australia.     

Invasive pneumococcal disease in Australia, 2001.

There were 1,681 cases of invasive pneumococcal disease (IPD) notified to the National Notifiable Diseases Surveillance System in Australia in 2001; a rate of 8.6 cases per 100,000 population. The notification rate varied between states and territories and by geographical region with the highest rates in the north of the country. Pneumococcal disease was reported most frequently in children aged less than 5 years (47.3 cases per 100,000 population). Enhanced surveillance for IPD was carried out in the Northern Territory, Western Australia, South Australia, Victoria, Tasmania and metropolitan areas of New South Wales, encompassing 72 per cent of the population and providing additional data on 86 per cent of all notified cases. Enhanced surveillance data revealed high rates of pneumococcal disease in Indigenous Australians. Rates of IPD in Indigenous children aged less than 5 years were as high as 483 cases per 100,000 population in the Northern Territory. The clinical presentation of IPD was most commonly pneumonia (56%) and bacteraemia (36%). There were 125 deaths attributed to IPD resulting in an overall case fatality rate of 8.6 per cent. More than half (54%) of all cases had a recognised risk factor for IPD. Eighty-six per cent of serotypes identified in non-indigenous children compared with only 55% of serotypes in Indigenous children were in the 7-valent vaccine. Antibiotic susceptibility testing showed reduced susceptibility to penicillin in 12 per cent, and to third generation cephalosporins in 5 per cent of isolates. These are the first national data available on IPD in Australia and will assist in evaluating the impact of the newly introduced conjugate vaccine and guide overall pneumococcal vaccine strategies.     

Serotype changes in adult invasive pneumococcal infections in Portugal did not reduce the high fraction of potentially vaccine preventable infections

We determined the serotype and antimicrobial susceptibility of 1100 isolates responsible for adult invasive pneumococcal infections (IPD) in Portugal between 2006 and 2008. Serotypes 3 (13%), 1 (12%), 7F (11%), 19A (10%) and 14 (7%) were the most frequent causes of IPD and the two later serotypes accounted for the majority of erythromycin and penicillin nonsusceptible isolates. Serotype 1 was associated with younger adults whereas serotype 3 was associated with older adults. Despite the availability of the 23-valent polysaccharide vaccine (PPV23) in Portugal since 1996, the proportion of PPV23 preventable IPD remained stable and above 80%. Comparing with previous data from Portugal, we showed a continued decline of the serotypes included in the 7-valent conjugate vaccine (PCV7) in adult IPD and a rise of serotypes included in the 13-valent conjugate vaccine, increasing its potential coverage of adult IPD to 70% in 2008. Penicillin non-susceptibility remained stable (17%) whereas erythromycin resistance (18%) has continued to rise in the post-PCV7 years.     

Evaluation of impact of 23 valent pneumococcal polysaccharide vaccine following 7 valent pneumococcal conjugate vaccine in Australian Indigenous children

BackgroundHigh incidence and serotype diversity of invasive pneumococcal disease (IPD) in Indigenous children in remote Australia led to rapid introduction of 7-valent conjugate pneumococcal vaccine (7vPCV) at 2, 4 and 6 months in 2001, followed by 23-valent polysaccharide pneumococcal vaccine (23vPPV) in the second year of life. All other Australian children were offered 3 doses of 7vPCV without a booster from 2005. This study evaluated the impact of the unique pneumococcal vaccine schedule of 7vPCV followed by the 23vPPV booster among Indigenous Australian children.MethodsChanges in IPD incidence derived from population-based passive laboratory surveillance in Indigenous children <5 years eligible for 23vPPV were compared to non-Indigenous eligible for 7vPCV only from the pre-vaccine introduction period (Indigenous 1994–2000; non-Indigenous 2002–2004) to the post-vaccine period (2008–2010 in both groups) using incidence rate ratios (IRRs) stratified by age into serotype groupings of vaccine (7v and 13vPCV and 23vPPV) and non-vaccine types. Vaccine coverage was assessed from the Australian Childhood Immunisation Register.ResultsAt baseline, total IPD incidence per 100,000 was 216 (n = 230) in Indigenous versus 55 (n = 1993) in non-Indigenous children. In 2008–2010, IRRs for 7vPCV type IPD were 0.03 in both groups, but for 23v-non7v type IPD 1.2 (95% CI 0.8–1.8) in Indigenous versus 3.1 (95% CI 2.5–3.7) in non-Indigenous, difference driven primarily by serotype 19A IPD (IRR 0.6 in Indigenous versus 4.3 in non-Indigenous). For non-7vPCV type IPD overall, IRR was significantly higher in those age-eligible for 23vPPV booster compared to those younger, but in both age groups was lower than for non-Indigenous children.ConclusionThese ecologic data suggest a possible “serotype replacement sparing” effect of 23vPPV following 7vPCV priming, especially for serotype 19A with supportive evidence from other immunogenicity and carriage studies. Applicability post 10vPCV or 13v PCV priming in similar settings would depend on local serotype distribution of IPD.     

Serotypes 1, 7F and 19A became the leading causes of pediatric invasive pneumococcal infections in Portugal after 7 years of heptavalent conjugate vaccine use

We characterized 353 isolates responsible for pediatric invasive pneumococcal infections (IPD) in Portugal between 2006 and 2008. Serotypes included in the seven-valent conjugate vaccine (PCV7) accounted for 17% of IPD. Serotypes 1, 7F and 19A were the most frequent causes of IPD and the later consolidated as the most frequent serotype among erythromycin and penicillin non-susceptible isolates. Serotype 1 was associated with older children and empyemas, while serotype 19A was associated with IPD in younger (<2 years) children. The higher valency vaccines PCV10 and PCV13 have a potentially superior coverage, 55% and 83% respectively, but non-vaccine serotypes are emerging as important causes of IPD. A decline of resistance with patient age was noted. Comparing with previous data from Portugal, this study showed a continued decline of PCV7 serotypes and that overall resistance has stabilized following the initial decline of the first post-PCV7 years.     

Invasive pneumococcal disease in New Zealand 1998-2005: capsular serotypes and antimicrobial resistance

Isolates from 3903 cases of invasive pneumococcal disease (IPD) were referred to the national reference laboratory over the 8 years, 1998-2005, as part of the laboratory-based surveillance of this disease in New Zealand. All isolates were serotyped and their antimicrobial susceptibility was tested. The incidence of IPD was highest in young children, with an average annual incidence of 100.8/100,000 in infants aged <2 years. There were changes in the prevalence of several of the serotypes during the 8-year period. Overall the seven serotypes included in the 7-valent pneumococcal conjugate vaccine, 4, 6B, 9V, 14, 18C, 19F and 23F, were the most common serotypes and accounted for 80.9% of the disease in infants aged <2 years. There was no overall change in penicillin resistance or non-susceptibility during the 8 years, and rates were 7.1% and 17.1%, respectively, in 2005. In contrast, cefotaxime and erythromycin resistance increased to reach 3.1% and 12.2%, respectively, by 2005.     

Systemic pneumococcal disease in Norway 1995-2001: capsular serotypes and antimicrobial resistance

A total of 4624 pneumococcal isolates from episodes of systemic pneumococcal disease were received at the Norwegian Institute of Public Health during the period 1995-2001. All isolates were serotyped and tested for susceptibility to benzylpenicillin, lincomycin, erythromycin, tetracycline and trimethroprim sulphamethoxazole. The proportion of strains resistant to these antimicrobial agents remained stable at a low level, ranging from 0.1% for benzylpenicillin to 2.5% for erythromycin. The distribution of serotypes was also stable over the 7 years: serotypes 1, 4, 9, 14, 7, 6 and 23 were the most frequent, representing 70.5% of isolates. Overall, 95.8% of the isolates were of serotypes/groups included in the current 23-valent polysaccharide vaccine, 52.2% were of serotypes/groups included in the 7-valent conjugated vaccine and 85.5% were of serotypes/groups included in the 11-valent conjugated vaccine.     

Summary of invasive pneumococcal disease burden among children in the Asia-Pacific region

Invasive pneumococcal disease (IPD) burden is significant in the Asia-Pacific region. This review describes the epidemiology and Streptococcus pneumoniae (SP) serotype distribution of IPD in children in the Asia-Pacific region from studies published from 1999 to 2010. IPD incidence varies widely in Asia-Pacific countries depending on the method of surveillance, the population studied, and the time period. Incidences are highest for younger children, with rates near 100–200 cases per 100,000 children aged <1 or 2 years. Incidences of preventable disease are estimated to be 6–200 cases per 100,000. Heptavalent pneumococcal conjugate vaccine (PCV7) serotype coverage shows a very wide range over the Asia-Pacific region. Ten countries have high vaccine serotype coverage (>70%), and six countries have low vaccine serotype coverage (<50%). The majority of SP serotypes in children with IPD in most countries in the Asia-Pacific region are susceptible to penicillin (intermediate and resistant <50%); a few countries have SP serotypes with high level resistance to penicillin (intermediate and resistant >50%). Japan, Taiwan, and Thailand have high PCV7 serotype coverage. Countries with low pneumococcal resistance to antimicrobials have shown increasingly higher nonsusceptibility with time. National vaccination programmes that include PCV7, 10-valent pneumococcal conjugate vaccine (PCV), or 13-valent PCV would significantly affect IPD burden in children aged <5 years in the Asia-Pacific region, as well as the burden of penicillin-nonsusceptible IPD.     

Streptococcus pneumoniae serotypes in Utah adults at the end of the PCV7 era

While heptavalent pneumococcal conjugate vaccine (PCV) has decreased vaccine type invasive pneumococcal disease (IPD) nationwide, rapid serotype replacement and increasing parapneumonic empyema, has been reported in Utah children. The effect of pediatric vaccination on adults in this population is unknown.We identified 117 adults with IPD from the Intermountain Healthcare Central Laboratory between November 2009 and October 2010. We serotyped 61 (52%) stored isolates. We compared the serotype distribution of adult IPD isolates with that of pediatric isolates collected in 2009-2010.PCV7 serotypes were rare in adults (3%) and children (3%). Emerging 13-valent PCV serotypes 3, 7F, and 19A caused the majority of IPD in adults (63%) and children (56%). Fifty-one (84%) adult isolates were serotypes included in 23-valent polysaccharide vaccine and 66% in PCV13.Adult and pediatric IPD serotypes are closely associated in Utah. PCV13 vaccination in Utah children is likely to significantly impact IPD in Utah adults.     

Has the seven-valent pneumococcal conjugate vaccine had an impact on invasive pneumococcal disease in Western Australia?

Enhanced surveillance for invasive pneumococcal disease (IPD) has been ongoing in Western Australia since 1996. We describe the epidemiology of invasive pneumococcal disease in children aged <2 years between 1996 and 2005. Pneumococcal conjugate vaccine has been offered to Aboriginal children and other high-risk children since July 2001 and to all Australian children since January 2005. A total of 1655 IPD cases were reported of whom 361 (55 Aboriginal) were aged <2 years. From 1996-2001 to 2002-2005, IPD incidence declined from 192 to 124/100,000/annum in Aboriginal children and from 70 to 56/100,000/annum in non-Aboriginal children. Incidence of IPD due to vaccine serotypes (VT) declined from 118 to 43/100,000/annum (p=0.05) in Aboriginal children and from 59 to 45/100,000/annum in non-Aboriginal children (p<0.001), with no increased incidence of disease due to non-vaccine serotypes. Continued surveillance is essential to measure the impact of the childhood pneumococcal conjugate vaccination program on IPD incidence and to identify the emergence of disease due to non-vaccine serotypes.     

Increasing non-susceptibility to antibiotics within carried pneumococcal serotypes — Alaska, 2008–2015

BackgroundIn Alaska, while introduction of 13-valent pneumococcal conjugate vaccine led to declines in invasive pneumococcal disease, carriage prevalence remained stable because of replacement with non-vaccine serotypes. We assessed antibiotic non-susceptibility of carried pneumococci during serotype redistribution, determined the contributions of within-serotype shifts, and assessed factors that could explain changes in non-susceptibility.MethodsEach year from 2008 to 2015, at multiple sites in Alaska, we collected nasopharyngeal swabs and completed surveys for a convenience sample of participants. Pneumococcal serotyping and antimicrobial susceptibility testing for penicillin and erythromycin were performed. We described changes in non-susceptibility of isolates from 2008–2011 to 2012–2015, and assessed the contributions of serotype redistribution and within-serotype changes in non-susceptibility by comparing observed data to modeled data removing either factor. We used weighted logistic regression to assess whether reported risk factors could explain changes over time in non-susceptibility within serotypes.ResultsFrom 2008–2011 to 2012–2015, the overall proportion of isolates non-susceptible to penicillin or erythromycin increased by 3%, from 23% (n = 1,183) to 26% (n = 1,589; P < 0.05). However, a decrease of 3% would be expected if serotype redistribution occurred without within-serotype changes in non-susceptibility. Standardization by either factor produced hypothetical data significantly different to observed data. Within serotypes, the average annual increase in odds of non-susceptibility to penicillin or erythromycin was 1.08 (95% CI 1.05–1.11). Recent antibiotic exposure, urban residence and increased household size of participants predicted isolate non-susceptibility but did not explain the increase over time.DiscussionAn overall increase in non-susceptibility of carried pneumococcal isolates to penicillin or erythromycin resulted from increases in non-susceptibility within serotypes, which outweighed a protective effect of serotype redistribution. Characterization of emerging resistant clones within carried non-vaccine serotypes, including risk factors for colonization and disease, would support disease prevention efforts and inform vaccine strategies.     

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.     

Fluoroquinolone and other antimicrobial resistance in invasive pneumococci, Hong Kong, 1995-2001

We determined the susceptibilities of 265 invasive isolates of pneumococci obtained during 1995 to 2001 in Hong Kong to 11 antimicrobial agents and their serotypes. Overall, 62.6% isolates were susceptible to penicillin, 20% were intermediately resistant, and 17.4% were resistant. The overall prevalence of levofloxacin resistance (MIC > or = 8 microg/mL) was 3.8% but increased to 15.2% among the penicillin-resistant isolates. All levofloxacin-resistant isolates were clonally related; had reduced susceptibility to penicillin, cefotaxime, and clarithromycin; and were derived from adults > or = 50 years of age. Of the penicillin-nonsusceptible pneumococci, 90% from children < or = 5 years of age and 54.8% from persons of all ages were of serotypes that are included in the 7-valent pneumococcal conjugate vaccine; 93.5% from children < or = 5 years of age and 93% from persons of all ages were of serotypes that are included in the 23-valent polysaccharide vaccine.     

Serotype distribution of invasive Streptococcus pneumoniae in adults 65 years of age and over after the introduction of childhood 13-valent pneumococcal conjugate vaccination programs in Canada, 2010–2016

The 13-valent conjugate vaccine (PCV13) was recommended for childhood immunization programs in 2010 in Canada and has decreased the incidence of invasive pneumococcal disease (IPD) in children and changed the epidemiology of IPD in adults. This study investigated the epidemiology of IPD in adults 65 years of age and older in Canada. A total of 7282 invasive S. pneumoniae isolated from adults ≥65 years old were serotyped from 2010 to 2016 and antimicrobial susceptibility was performed on 2527 isolates. Serotyping was performed by Quellung reaction using commercial antisera and antimicrobial susceptibilities were determined by broth microdilution. PCV7 serotypes decreased non-significantly from 2010 to 2016 from 9.1% (n = 96) to 6.7% (n = 72) while the additional six PCV13 serotypes declined significantly from 39.5% (n = 418) to 18.6% (n = 201) (p < 0.05). The 23-valent pneumococcal polysaccharide vaccine (PPV23) and non-vaccine (NVT) serotypes increased from 26.3% (n = 278) to 36.2% (n = 393) (p < 0.05), and from 25.1% (n = 266) to 38.4% (n = 416) (p < 0.05), respectively. There were no significant changes in antimicrobial resistance rates from 2011 to 2016: 24.1% of the IPD from adults ≥65 years were resistant to clarithromycin (n = 609), 10.0% to doxycycline (n = 254), 11.8% to penicillin (n = 299), 5.2% to cefuroxime (n = 131), 6.6% to clindamycin (n = 168), 6.0% to trimethoprim-sulfamethoxazole (n = 152), and 0.5% (n = 12) to ceftriaxone. Although overall incidence of IPD in adults ≥65 years has remained relatively constant from 2010 to 2016, childhood PCV13 vaccination programs have been successful in indirectly reducing IPD caused by PCV13 serotypes in adults through herd immunity effects.