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The Dynamic Epidemiology of Streptococcus pneumoniae
1. The Dynamic Epidemiology of
Streptococcus pneumoniae.
Joshua P. Metlay, MD, PhD
Division of General Internal Medicine
University of Pennsylvania
Presented at the 41st Annual Symposium
“Global Movement of Infectious Pathogens and Improved Laboratory Detection”
Eastern PA Branch-American Society for Microbiology
November 17, 2011
Thomas Jefferson University, Philadelphia
2. Outline
• Introduction to pneumococcal disease
• Secular trends
–Antimicrobial drug resistance
(macrolides)
–Serotype replacement
• Geographic patterns
5. Penicillin Resistance in S. pneumoniae
United States 1979-2000
Sentinel ABCs
1979-1994: CDC Sentinel Surveillance Network
1995-2002: CDC Active Bacterial Core Surveillance (ABCs) /Emerging Infections Program
6.
7. The Delaware Valley Hospital Network
• Hospital based reporting of cases of
pneumococcal bacteremia
• Established in 2001
• Centralized susceptibility testing
• 48 hospitals in the 5 county region of
Southeastern Pennsylvania
• 3.7 million population
• 400 annual cases
14. What is Herd Immunity?
Picture courtesy of Dr. C. Whitney
15. Early Successes with Vaccination
Rate of VT IPD per 100,000 population
Direct effect:
94% decrease
Indirect effect:
65% decrease
CDC. MMWR 2005; 54: 893-7.
16. Vaccination of children reduces risk of
disease in adults
100 Cases
Controls
80
60
%
40
20
0
Any child vaccinated Youngest child
vaccinated
Vaccine. 2006
18. CLSI Breakpoints 2011
Drug MIC (ug/mL)
Interpretive Standard
S I R
Penicillin (Meningitis) ≤ 0.06 0.12-1 ≥2
Penicillin (Non-meningitis) ≤2 4 ≥8
Erythromycin ≤0.25 0.5 ≥1
31. Why are there clusters of disease?
• Small area outbreaks from highly virulent
clones
– Pathogen Hypothesis
• Neighborhood level exposures influence risk
of transmission
– Vector Hypothesis
• Heterogenous population distribution
– Host Hypothesis
40. Child Exposure is Associated with
Reduced Risk of Disease
Characteristic Cases per 100,000 95% CI
# of children in
home
0 21.5 20.3 – 22.8
1 8.3 6.8 – 9.9
2+ 3.3 2.6 – 4.2
Archives of Internal Med 2010
41. Key Points
• Overall risk of pneumococcal disease has
declined but new serotypes are emerging
• Emerging serotypes are primarily multidrug
resistance, reflecting selection of MDR clones
and expansion of previously low prevalence
serotypes
• Variation in disease risk likely reflects host
factors, but vector and pathogen factors are
rapidly changing in pneumococcal disease.
42. Thanks
• Robert Austrian • Marshall Joffe
• Lou Bell • Ebb Lautenbach
• Catherine Berjohn • Yimei Li
• Charlie Branas • Zhenying Liu
• Linda Crossette • Russell Localio
• Chris Czaja • Mat Macdonald
• Paul Edelstein • Irv Nachamkin
• Kristen Feemster • Samir Shah
• Neil Fishman • Justine Shults
• James Flory • Tony Smith