Vaccine-derived poliomyelitis 12 years after infection in Minnesota.

A 44-year-old woman with long-standing common variable immunodeficiency who was receiving intravenous immune globulin suddenly had paralysis of all four limbs and the respiratory muscles, resulting in death. Type 2 vaccine-derived poliovirus was isolated from stool. The viral capsid protein VP1 region had diverged from the vaccine strain at 12.3% of nucleotide positions, and the two attenuating substitutions had reverted to the wild-type sequence. Infection probably occurred 11.9 years earlier (95% confidence interval [CI], 10.9 to 13.2), when her child received the oral poliovirus vaccine. No secondary cases were identified among close contacts or 2038 screened health care workers. Patients with common variable immunodeficiency can be chronically infected with poliovirus, and poliomyelitis can develop despite treatment with intravenous immune globulin.

Effect of the 2009 influenza A(H1N1) pandemic on invasive pneumococcal pneumonia.

BACKGROUND: Because pneumococcal pneumonia was prevalent during previous influenza pandemics, we evaluated invasive pneumococcal pneumonia (IPP) rates during the 2009 influenza A(H1N1) pandemic. METHODS: We identified laboratory-confirmed, influenza-associated hospitalizations and IPP cases (pneumococcus isolated from normally sterile sites with discharge diagnoses of pneumonia) using active, population-based surveillance in the United States. We compared IPP rates during peak pandemic months (April 2009-March 2010) to mean IPP rates in nonpandemic years (April 2004-March 2009) and, using Poisson models, to 2006-2008 influenza seasons. RESULTS: Higher IPP rates occurred during the peak pandemic month compared to nonpandemic periods in 5-24 (IPP rate per 10 million: 48 vs 9 (95% confidence interval [CI], 5-13), 25-49 (74 vs 53 [CI, 41-65]), 50-64 (188 vs 114 [CI, 85-143]), and ≥65-year-olds (229 vs 187 [CI, 159-216]). In the models with seasonal influenza rates included, observed IPP rates during the pandemic peak were within the predicted 95% CIs, suggesting this increase was not greater than observed with seasonal influenza. CONCLUSIONS: The recent influenza pandemic likely resulted in an out-of-season IPP peak among persons ≥5 years. The IPP peak's magnitude was similar to that seen during seasonal influenza epidemics.

Epidemiology of invasive pneumococcal disease among high-risk adults since the introduction of pneumococcal conjugate vaccine for children.

BACKGROUND: Certain chronic diseases increase risk for invasive pneumococcal disease (IPD) and are indications for receipt of 23-valent pneumococcal polysaccharide vaccine (PPV23). Since the pediatric introduction of 7-valent pneumococcal conjugate vaccine (PCV7) in 2000, incidence of IPD among adults has declined. The relative magnitude of these indirect effects among persons with and without PPV23 indications is unknown. METHODS: We evaluated IPD incidence among adults with and without PPV23 indications using population- and laboratory-based data collected during 1998-2009 and estimates of the denominator populations with PPV23 indications from the National Health Interview Survey. We compared rates before and after PCV7 use by age, race, PPV23 indication, and serotype. RESULTS: The proportion of adult IPD cases with PPV23 indications increased from 51% before to 61% after PCV7 introduction (P < .0001). PCV7-serotype IPD declined among all race, age, and PPV23 indication strata, ranging from 82% to 97%. Overall IPD rates declined in most strata, by up to 65%. However, incidence remained highest among adults with PPV23 indications compared with those without (34.9 vs 8.8 cases per 100 000 population, respectively). Apart from age ≥65 years, diabetes is now the most common indication for PPV23 (20% of all cases vs 10% of cases in 1998-1999). CONCLUSIONS: Although IPD rates have declined among adults, adults with underlying conditions remain at increased risk of IPD and comprise a larger proportion of adult IPD cases in 2009 compared with 2000. A continued increase in the prevalence of diabetes among US adults could lead to increased burden of pneumococcal disease.

Effect of pneumococcal conjugate vaccine on pneumococcal meningitis.

BACKGROUND: Invasive pneumococcal disease declined among children and adults after the introduction of the pediatric heptavalent pneumococcal conjugate vaccine (PCV7) in 2000, but its effect on pneumococcal meningitis is unclear. METHODS: We examined trends in pneumococcal meningitis from 1998 through 2005 using active, population-based surveillance data from eight sites in the United States. Isolates were grouped into PCV7 serotypes (4, 6B, 9V, 14, 18C, 19F, and 23F), PCV7-related serotypes (6A, 9A, 9L, 9N, 18A, 18B, 18F, 19B, 19C, 23A, and 23B), and non-PCV7 serotypes (all others). Changes in the incidence of pneumococcal meningitis were assessed against baseline values from 1998-1999. RESULTS: We identified 1379 cases of pneumococcal meningitis. The incidence declined from 1.13 cases to 0.79 case per 100,000 persons between 1998-1999 and 2004-2005 (a 30.1% decline, P<0.001). Among persons younger than 2 years of age and those 65 years of age or older, the incidence decreased during the study period by 64.0% and 54.0%, respectively (P<0.001 for both groups). Rates of PCV7-serotype meningitis declined from 0.66 case to 0.18 case (a 73.3% decline, P<0.001) among patients of all ages. Although rates of PCV7-related-serotype disease decreased by 32.1% (P=0.08), rates of non-PCV7-serotype disease increased from 0.32 to 0.51 (an increase of 60.5%, P<0.001). The percentages of cases from non-PCV7 serotypes 19A, 22F, and 35B each increased significantly during the study period. On average, 27.8% of isolates were nonsusceptible to penicillin, but fewer isolates were nonsusceptible to chloramphenicol (5.7%), meropenem (16.6%), and cefotaxime (11.8%). The proportion of penicillin-nonsusceptible isolates decreased between 1998 and 2003 (from 32.0% to 19.4%, P=0.01) but increased between 2003 and 2005 (from 19.4% to 30.1%, P=0.03). CONCLUSIONS: Rates of pneumococcal meningitis have decreased among children and adults since PCV7 was introduced. Although the overall effect of the vaccine remains substantial, a recent increase in meningitis caused by non-PCV7 serotypes, including strains nonsusceptible to antibiotics, is a concern.

Geographic variation in invasive pneumococcal disease following pneumococcal conjugate vaccine introduction in the United States.

BACKGROUND: Rates of invasive pneumococcal disease (IPD) varied among the United States before pneumococcal conjugate vaccine (PCV7) introduction. We compared trends in IPD rates among diverse US sites over 10 years since PCV7 introduction. METHODS: Patients with IPD of all ages were identified through active population and laboratory-based surveillance in 8 geographic areas under continuous surveillance during 1998-2009. Isolates were serotyped. IPD incidence rates and percent changes were calculated by site, serotype group, age, and year. RESULTS: Reductions in rates of IPD ranged, by site, from 19 to 29.9 cases per 100,000 population during 1998-1999 to 11.2-18.0 cases per 100,000 population during 2009 (rate reduction, 5.1-15.3 cases per 100,000 population). Reductions in IPD rates among children aged <5 years ranged from 35.7 to 117.2 cases per 100,000 population across the sites. Reductions in rates of IPD due to PCV7 serotypes were seen in all age groups at all sites, ranging from 12 to 21.4 cases per 100,000 population during 1998-1999 to <2 cases per 100,000 population during 2009 (92%-98% reductions). Serotype 19A rates ranged from 0.4 to 1.5 cases per 100,000 population during 1998-1999 to 1.3 to 3.4 cases per 100,000 population during 2009 (rate difference, 0.9-2.8 cases per 100,000 population); modest increases were observed for most age groups across the sites. Rates of IPD due to all other serotypes ranged from 6.3 to 10.3 cases per 100,000 population during 1998-1999 to 8.3-13.6 cases per 100,000 population during 2009 (rate difference, -0.4 to 5.7 cases per 100,000 population). Across the sites, the greatest rate increases were seen in the 50-64 and >65 year age groups. CONCLUSIONS: Reductions in IPD due to vaccine serotypes were consistent across sites. Changes in serotype 19A and all other serotypes were variable. Although relative increases in non-vaccine type serotypes were large in some sites, absolute rate increases were small.

Sustained reductions in invasive pneumococcal disease in the era of conjugate vaccine.

BACKGROUND: Changes in invasive pneumococcal disease (IPD) incidence were evaluated after 7 years of 7-valent pneumococcal conjugate vaccine (PCV7) use in US children. METHODS: Laboratory-confirmed IPD cases were identified during 1998-2007 by 8 active population-based surveillance sites. We compared overall, age group-specific, syndrome-specific, and serotype group-specific IPD incidence in 2007 with that in 1998-1999 (before PCV7) and assessed potential serotype coverage of new conjugate vaccine formulations. RESULTS: Overall and PCV7-type IPD incidence declined by 45% (from 24.4 to 13.5 cases per 100,000 population) and 94% (from 15.5 to 1.0 cases per 100,000 population), respectively (P< .01 all age groups). The incidence of IPD caused by serotype 19A and other non-PCV7 types increased from 0.8 to 2.7 cases per 100,000 population and from 6.1 to 7.9 cases per 100,000 population, respectively (P< .01 for all age groups). The rates of meningitis and invasive pneumonia caused by non-PCV7 types increased for all age groups (P< .05), whereas the rates of primary bacteremia caused by these serotypes did not change. In 2006-2007, PCV7 types caused 2% of IPD cases, and the 6 additional serotypes included in an investigational 13-valent conjugate vaccine caused 63% of IPD cases among children <5 years-old. CONCLUSIONS: Dramatic reductions in IPD after PCV7 introduction in the United States remain evident 7 years later. IPD rates caused by serotype 19A and other non-PCV7 types have increased but remain low relative to decreases in PCV7-type IPD.

A community outbreak of conjunctivitis caused by nontypeable Streptococcus pneumoniae in Minnesota.

BACKGROUND: The Minnesota Department of Health (MDH) was notified of an outbreak of conjunctivitis in city A with cultures positive for Streptococcus pneumoniae. METHODS: MDH staff contacted clinics and schools in city A and city B regarding conjunctivitis cases, reviewed clinical findings of conjunctivitis cases in city A and collected isolates for subtyping. RESULTS: Between September 1 and December 12, 2003, cities A and B reported 735 conjunctivitis cases. Fifty-one percent of the cases were reported from schools, childcare centers and colleges. Adults were more likely to report itching, burning or swelling of the eye(s); children were more likely to report crusty eyes (P < 0.05). Forty-nine percent of conjunctival cultures (71 of 144) were positive for S. pneumoniae. All isolates were nontypeable by serotyping. Pulsed field gel electrophoresis identified 3 clonal groups with 84% of isolates belonging to one clonal group. Multilocus sequence typing revealed that isolates had the same multilocus sequence type as isolates from a 2002 outbreak at a New England college. CONCLUSIONS: This outbreak was widespread in the community and conjunctivitis clinical presentation varied by age. The predominant strains in this outbreak were related to a pneumococcal strain implicated in prior conjunctivitis outbreaks, suggesting these strains have a predilection for causing conjunctivitis.

Invasive pneumococcal disease among infants before and after introduction of pneumococcal conjugate vaccine.

CONTEXT: Streptococcus pneumoniae is a serious infection in young infants. A heptavalent pneumococcal conjugate vaccine (PCV7) was licensed in 2000 and recommended for all children aged 2 to 23 months. OBJECTIVE: To determine the rates of invasive pneumococcal disease (IPD) in young infants before and after PCV7 was incorporated into the childhood immunization schedule in June 2000. DESIGN, SETTING, AND PARTICIPANTS: A prospective, population-based study of infants aged 0 to 90 days who resided in areas in 8 US states with active laboratory surveillance for invasive S pneumoniae infections from July 1, 1997, to June 30, 2004. MAIN OUTCOME MEASURES: Rates of laboratory-confirmed IPD before (July 1, 1997-June 30, 2000) and after (July 1, 2001-June 30, 2004) PCV7 introduction, excluding a transition year (July 1, 2000-June 30, 2001). RESULTS: There were 146 cases of IPD, 89 before and 57 after PCV7 introduction. Isolated bacteremia occurred in 94 cases (64%), pneumonia in 27 (18%), meningitis in 22 (15%), and septic arthritis and/or osteomyelitis in 3 (2%). Mean rates of IPD for infants aged 0 to 90 days decreased 40% from 11.8 (95% confidence interval [CI], 9.6-14.5) to 7.2 (95% CI, 5.6-9.4; P = .004) per 100 000 live births following PCV7 introduction. Among black infants, mean rates of IPD decreased significantly from 17.1 (95% CI, 11.9-24.6) to 5.3 (95% CI, 2.8-10.1; P = .001) per 100,000 live births, with a nonsignificant decrease from 9.6 (95% CI, 7.3-12.7) to 6.8 (95% CI, 4.9-9.4) per 100,000 live births for white infants. Rates of PCV7-serotype isolates decreased significantly from 7.3 (95% CI, 5.3-10.1) to 2.4 (95% CI, 1.6-3.8; P<.001) per 100,000 live births, while rates of non-PCV7 serotypes remained stable (P = .55). CONCLUSIONS: Since PCV7 introduction, rates of IPD in young infants have decreased significantly, providing evidence that vaccinating children aged 2 to 23 months has led to changes in pneumococcal carriage in infants too young to receive PCV7. With a significant decrease in rates of IPD among black infants, the previous racial difference has been eliminated.

Changing epidemiology of invasive pneumococcal disease among older adults in the era of pediatric pneumococcal conjugate vaccine.

CONTEXT: A conjugate vaccine targeting 7 pneumococcal serotypes was licensed for young children in 2000. In contrast to the 23-valent polysaccharide vaccine used in adults, the 7-valent conjugate vaccine affects pneumococcal carriage and transmission. Early after its introduction, incidence of invasive pneumococcal disease declined among older adults, a group at high risk for pneumococcal disease. OBJECTIVE: To determine among adults aged 50 years or older whether incidence of invasive pneumococcal disease, disease characteristics, or the spectrum of patients acquiring these illnesses have changed over the 4 years since pneumococcal conjugate vaccine licensure. DESIGN, SETTING, AND POPULATION: Population-based surveillance of invasive pneumococcal disease in 8 US geographic areas (total population, 18,813,000), 1998-2003. MAIN OUTCOME MEASURES: Incidence of invasive pneumococcal disease by pneumococcal serotype and other characteristics; frequency among case patients of comorbid conditions and other factors influencing mortality. RESULTS: Incidence of invasive pneumococcal disease among adults aged 50 years or older declined 28% (95% confidence interval [CI], -31% to -24%), from 40.8 cases/100,000 in 1998-1999 to 29.4 in 2002-2003. Among those aged 65 years or older, the 2002-2003 rate (41.7 cases/100,000) was lower than the Healthy People 2010 goal (42 cases/100,000). Among adults aged 50 years or older, incidence of disease caused by the 7 conjugate vaccine serotypes declined 55% (95% CI, -58% to -51%) from 22.4 to 10.2 cases/100,000. In contrast, disease caused by any of the 16 serotypes only in polysaccharide vaccine did not change, and disease caused by serotypes not in either vaccine increased somewhat, from 6.0 to 6.8 cases/100,000 (13%; 95% CI, 1% to 27%). Between 1998-1999 and 2002-2003, the proportion of case-patients with human immunodeficiency virus infection increased from 1.7% (47/2737) to 5.6% (124/2231) (P<.001), and those with any comorbid condition that is an indication for pneumococcal polysaccharide vaccination increased from 62.3% (1842/2955) to 72.0% (1721/2390) (P<.001). CONCLUSIONS: Our findings indicate that use of conjugate vaccine in children has substantially benefited older adults. However, persons with certain comorbid conditions may benefit less than healthier persons from the indirect effects of the new vaccine.

Effect of use of 13-valent pneumococcal conjugate vaccine in children on invasive pneumococcal disease in children and adults in the USA: analysis of multisite, population-based surveillance.

BACKGROUND: In 2000, seven-valent pneumococcal conjugate vaccine (PCV7) was introduced in the USA and resulted in dramatic reductions in invasive pneumococcal disease (IPD) and moderate increases in non-PCV7 type IPD. In 2010, PCV13 replaced PCV7 in the US immunisation schedule. We aimed to assess the effect of use of PCV13 in children on IPD in children and adults in the USA. METHODS: We used laboratory-based and population-based data on incidence of IPD from the Active Bacterial Core surveillance (part of the Centers for Disease Control and Prevention's Emerging Infections Program) in a time-series model to compare rates of IPD before and after the introduction of PCV13. Cases of IPD between July 1, 2004, and June 30, 2013, were classified as being caused by the PCV13 serotypes against which PCV7 has no effect (PCV13 minus PCV7). In a time-series model, we used an expected outcomes approach to compare the reported incidence of IPD to that which would have been expected if PCV13 had not replaced PCV7. FINDINGS: Compared with incidence expected among children younger than 5 years if PCV7 alone had been continued, incidence of IPD overall declined by 64% (95% interval estimate [95% IE] 59-68) and IPD caused by PCV13 minus PCV7 serotypes declined by 93% (91-94), by July, 2012, to June, 2013. Among adults, incidence of IPD overall also declined by 12-32% and IPD caused by PCV13 minus PCV7 type IPD declined by 58-72%, depending on age. We estimated that over 30 000 cases of IPD and 3000 deaths were averted in the first 3 years after the introduction of PCV13. INTERPRETATION: PCV13 reduced IPD across all age groups when used routinely in children in the USA. These findings provide reassurance that, similar to PCV7, PCVs with additional serotypes can also prevent transmission to unvaccinated populations. FUNDING: Centers for Disease Control and Prevention.

Invasive Haemophilus influenzae Disease in Adults ≥65 Years, United States, 2011.

BACKGROUND: Since the introduction of the Haemophilus influenzae serotype b vaccine, H influenzae epidemiology has shifted. In the United States, the largest burden of disease is now in adults aged ≥65 years. However, few data exist on risk factors for disease severity and outcome in this age group. METHODS: A retrospective case-series review of invasive H influenzae infections in patients aged ≥65 years was conducted for hospitalized cases reported to Active Bacterial Core surveillance in 2011. RESULTS: There were 299 hospitalized cases included in the analysis. The majority of cases were caused by nontypeable H influenzae, and the overall case fatality ratio (CFR) was 19.5%. Three or more underlying conditions were present in 63% of cases; 94% of cases had at least 1. Patients with chronic heart conditions (congestive heart failure, coronary artery disease, and/or atrial fibrillation) (odds ratio [OR], 3.27; 95% confidence interval [CI], 1.65-6.46), patients from private residences (OR, 8.75; 95% CI, 2.13-35.95), and patients who were not resuscitate status (OR, 2.72; 95% CI, 1.31-5.66) were more likely to be admitted to the intensive care unit (ICU). Intensive care unit admission (OR, 3.75; 95% CI, 1.71-8.22) and do not resuscitate status (OR, 12.94; 95% CI, 4.84-34.55) were significantly associated with death. CONCLUSIONS: Within this age group, burden of disease and CFR both increased significantly as age increased. Using ICU admission as a proxy for disease severity, our findings suggest several conditions increased risk of disease severity and patients with severe disease were more likely to die. Further research is needed to determine the most effective approach to prevent H influenzae disease and mortality in older adults.

Cost of screening intensive care unit patients for methicillin-resistant Staphylococcus aureus in hospitals.

BACKGROUND: The objective of this study is to determine the costs per hospital admission of screening intensive care unit patients for methicillin-resistant Staphylococcus aureus (MRSA) and isolating those who are colonized. METHODS: Data on the costs of the intervention come from the Minneapolis Veterans Affairs Medical Center, a 279-bed teaching hospital and outpatient facility. A microcosting approach is used to determine the intervention costs for 3 different laboratory testing protocols. The costs of caring for MRSA-infected patients come from the experience of 241 Minneapolis Veterans Affairs Medical Center patients with MRSA infections in 2004 through 2006. The effectiveness of the intervention comes from the extant literature. To capture the effect of screening on reducing transmission of MRSA to other patients and its effect on costs, a Markov simulation model was employed. RESULTS: The intervention was cost saving compared with no intervention for all 3 laboratory processes evaluated and for all of the 1-way sensitivity analyses considered. CONCLUSION: Because of the high cost of caring for a MRSA patient, interventions that reduce the spread of infections-such as screening intensive care unit patients upon admission studied here-are likely to pay for themselves.

Excess costs and utilization associated with methicillin resistance for patients with Staphylococcus aureus infection.

OBJECTIVE: To determine differences in healthcare costs between cases of methicillin-susceptible Staphylococcus aureus (MSSA) infection and methicillin-resistant S. aureus (MRSA) infection in adults. DESIGN: Retrospective study of all cases of S. aureus infection. SETTING: Department of Veterans Affairs hospital and associated clinics. PATIENTS: There were 390 patients with MSSA infections and 335 patients with MRSA infections. METHODS: We used medical records, accounting systems, and interviews to identify services rendered and costs for Minneapolis Veterans Affairs Medical Center patients with S. aureus infection with onset during the period from January 1, 2004, through June 30, 2006. We used regression analysis to adjust for patient characteristics. RESULTS: Median 6-month unadjusted costs for patients infected with MRSA were $34,657, compared with $15,923 for patients infected with MSSA. Patients with MRSA infection had more comorbidities than patients with MSSA infection (mean Charlson index 4.3 vs 3.2; P < .001). For patients with Charlson indices of 3 or less, mean adjusted 6-month costs derived from multivariate analysis were $51,252 (95% CI, $46,041-$56,464) for MRSA infection and $30,158 (95% CI, $27,092-$33,225) for MSSA infection. For patients with Charlson indices of 4 or more, mean adjusted costs were $84,436 (95% CI, $79,843-$89,029) for MRSA infection and $59,245 (95% CI, $56,016-$62,473) for MSSA infection. Patients with MRSA infection were also more likely to die than were patients with MSSA infection (23.6% vs 11.5%; P < .001). MRSA infection was more likely to involve the lungs, bloodstream, and urinary tract, while MSSA infection was more likely to involve bones or joints; eyes, ears, nose, or throat; surgical sites; and skin or soft tissue (P < .001). CONCLUSIONS: Resistance to methicillin in S. aureus was independently associated with increased costs. Effective antimicrobial stewardship and infection prevention programs are needed to prevent these costly infections.

Epidemiologic investigation of immune-mediated polyradiculoneuropathy among abattoir workers exposed to porcine brain.

BACKGROUND: In October 2007, a cluster of patients experiencing a novel polyradiculoneuropathy was identified at a pork abattoir (Plant A). Patients worked in the primary carcass processing area (warm room); the majority processed severed heads (head-table). An investigation was initiated to determine risk factors for illness. METHODS AND RESULTS: Symptoms of the reported patients were unlike previously described occupational associated illnesses. A case-control study was conducted at Plant A. A case was defined as evidence of symptoms of peripheral neuropathy and compatible electrodiagnostic testing in a pork abattoir worker. Two control groups were used - randomly selected non-ill warm-room workers (n = 49), and all non-ill head-table workers (n = 56). Consenting cases and controls were interviewed and blood and throat swabs were collected. The 26 largest U.S. pork abattoirs were surveyed to identify additional cases. Fifteen cases were identified at Plant A; illness onsets occurred during May 2004-November 2007. Median age was 32 years (range, 21-55 years). Cases were more likely than warm-room controls to have ever worked at the head-table (adjusted odds ratio [AOR], 6.6; 95% confidence interval [CI], 1.6-26.7), removed brains or removed muscle from the backs of heads (AOR, 10.3; 95% CI, 1.5-68.5), and worked within 0-10 feet of the brain removal operation (AOR, 9.9; 95% CI, 1.2-80.0). Associations remained when comparing head-table cases and head-table controls. Workers removed brains by using compressed air that liquefied brain and generated aerosolized droplets, exposing themselves and nearby workers. Eight additional cases were identified in the only two other abattoirs using this technique. The three abattoirs that used this technique have stopped brain removal, and no new cases have been reported after 24 months of follow up. Cases compared to controls had higher median interferon-gamma (IFNgamma) levels (21.7 pg/ml; vs 14.8 pg/ml, P<0.001). DISCUSSION: This novel polyradiculoneuropathy was associated with removing porcine brains with compressed air. An autoimmune mechanism is supported by higher levels of IFNgamma in cases than in controls consistent with other immune mediated illnesses occurring in association with neural tissue exposure. Abattoirs should not use compressed air to remove brains and should avoid procedures that aerosolize CNS tissue. This outbreak highlights the potential for respiratory or mucosal exposure to cause an immune-mediated illness in an occupational setting.

The changing epidemiology of pneumococcal pulmonary disease in the era of the heptavalent vaccine.

Since the pediatric pneumococcal 7-valent conjugate vaccine was licensed in the United States, dramatic changes have taken place in the occurrence of pneumococcal disease among children and adults. Incidence of invasive pneumococcal disease including bacteremic pneumonia has declined, but changes in noninvasive pulmonary disease have been more difficult to assess. This paper reviews evidence of the epidemiologic features of invasive pneumococcal disease and community-acquired pneumonia among children and adults since 2000. Despite some increases in non-vaccine-type disease, its use has resulted in major reductions in incidence of invasive pneumococcal disease in all age groups, particularly that of antibiotic-resistant disease and of pediatric pneumococcal pneumonia. Several studies show that changes in circulating pneumococcal strains may be producing differential changes in disease incidence and disease presentation in several populations, including HIV-infected individuals and Alaska Natives.

Population snapshot of emergent Streptococcus pneumoniae serotype 19A in the United States, 2005.

BACKGROUND: Serotype 19A invasive pneumococcal disease (IPD) increased annually in the United States after the introduction of the 7-valent conjugate vaccine (PCV7). To understand this increase, we characterized serotype 19A isolates recovered during 2005. METHODS: IPD cases during 1998-2005 were identified through population-based surveillance. We performed susceptibility testing and multilocus sequence typing on 528 (95%) of 554 serotype 19A isolates reported in 2005. RESULTS: The incidence of IPD due to serotype 19A increased from 0.8 to 2.5 cases per 100,000 population between 1998 and 2005 (P < .05), whereas the overall incidence of IPD decreased from 24.4 to 13.8 cases per 100,000 population (P < .05). Simultaneously, the incidence of IPD due to penicillin-resistant 19A isolates increased from 6.7% to 35% (P < .0001). Of 151 penicillin-resistant 19A isolates, 111 (73.5%) belonged to the rapidly emerging clonal complex 320, which is related to multidrug-resistant Taiwan(19F)-14. The remaining penicillin-resistant strains were highly related to other clones of PCV7 serotypes or to isolates within major 19A clonal complex 199 (CC199). In 1999, only CC199 and 3 minor clones were apparent among serotype 19A isolates. During 2005, 11 multiple-isolate clonal sets were detected, including capsular switch variants of a serotype 4 clone. CONCLUSIONS: PCV7 ineffectiveness against serotype 19A, antibiotic resistance, clonal expansion and emergence, and capsular switching have contributed to the genetic diversity of 19A and to its emergence as the predominant invasive pneumococcal serotype in the United States.

Aggregated antibiograms and monitoring of drug-resistant Streptococcus pneumoniae.

Community-specific antimicrobial susceptibility data may help monitor trends among drug-resistant Streptococcus pneumoniae and guide empiric therapy. Because active, population-based surveillance for invasive pneumococcal disease is accurate but resource intensive, we compared the proportion of penicillin-nonsusceptible isolates obtained from existing antibiograms, a less expensive system, to that obtained from 1 year of active surveillance for Georgia, Tennessee, California, Minnesota, Oregon, Maryland, Connecticut, and New York. For all sites, proportions of penicillin-nonsusceptible isolates from antibiograms were within 10 percentage points (median 3.65) of those from invasive-only isolates obtained through active surveillance. Only 23% of antibiograms distinguished between isolates intermediate and resistant to penicillin; 63% and 57% included susceptibility results for erythromycin and extended-spectrum cephalosporins, respectively. Aggregating existing hospital antibiograms is a simple and relatively accurate way to estimate local prevalence of penicillin-nonsusceptible pneumococcus; however, antibiograms offer limited data on isolates with intermediate and high-level penicillin resistance and isolates resistant to other agents.