Respiratory Tract Infections Bacterial

1. Respiratory Tract InfectionsBacterial Dr. Ross Davidson Rm 309, MacKenzie Building QE II HSC ph: 473-5520 ross.davidson@cdha.nshealth.ca

2. Respiratory Tract Infections • Pneumonia - community-acquired - hospital • AECB (AE-COPD) • Sinusitis • Otitis media

3. RTIs • 1st lecture – Common bacterial causes • 2nd lecture – Mycobacteria & atypical pathogens

4. RTI - specimens • Sputum • BAL / bronch washing • Naso-pharyngeal aspirates • Endotracheal aspirates • Sinus aspirates • Tympanocentesis

5. Respiratory Tract InfectionsCommon Pathogens • Streptococcus pneumoniae • Haemophilus influenzae • Moraxella catarrhalis • Mycoplasma pneumoniae • Chlamydophyla pneumoniae • Legionella pneumophila • S.aureus • B.pertussis • Gram-negatives / anaerobes Atypical Pathogens

6. Community Acquired Pneumoniaetiology S.pneumoniae H.influenzae Other Anaerobes L.pneumophilia M.pneumoniae C.pneumoniae

7. Respiratory Tract Infections • S.pneumoniae • Most common bacterial cause of RTIssmall gram positive diplococcialpha haemolytic, bile soluble, optochin Sgrowth often enhanced in CO2 atmospheremost are encapsulated (> 80 distinct types) • Colonizes the nasopharynx in 5-10% of adults and 20-40% of children • Incidence increases in winter months

8. Respiratory Tract Infections • Pathogenicity-adherence essential for colonization-capsule is important virulence factor - aids in escape from phagocytic cells • Predisposition to pneumococcal infection-defective Ab formation-insufficient numbers of PMNs-day-cares, military, prisons, shelters-chronic respiratory disease-infancy and aging-diabetes, alcoholism, liver disease

9. Pneumococcal Capsule

10. Respiratory Tract Infections • Pneumococcal vaccine23 different serotypesaccount for 90% of invasive strainsprotection wanes with time and age • Indications for vaccineadvanced age myelomasplenectomy alcoholismHIV / AIDs diabeteslymphoma • PREVNAR- conjugate vaccine - indicated for use in infants < 2 years of age

11. S.pneumoniae • Treatment- penicillins, cephalosporins, macrolides, fluoroquinolones • Choice of antibiotic - site of infection - co-morbidities - degree of illness - ambulatory / inpatient

12. Respiratory Tract Infections • Antibiotic resistance in S.pneumoniae- penicillin resistance is major concern - due to remodeling of the PBP- multi-drug resistance

13. oral / viridans Streptococci 0.03 g/ml S.pneumoniae 0.06 g/ml 0.12 g/ml 0.5 g/ml Penicillin Resistance inS.pneumoniae Minimum Inhibitory Concentration

14. Percentage of Penicillin Non-Susceptible S. pneumoniae in Canada: 1988-2005 16 % Intermediate Resistance 14 % High-level Resistance 12 10 8 6 4 2 0 1988 1993 1995 1997 1999 2001 2003 2005 Low, D: Canadian Bacterial Surveillance Network, Nov , 2005

15. % Resistance 25 High Res Intermediate Res 20 15 10 5 0 Pen-I Cefprozil TMP/SMX Amoxicillin Ceftriaxone Cefuroxime Gatifloxacin Tetracycline Moxifloxacin Levofloxacin Gemifloxacin Erythromycin Telithromycin Resistance in S.pneumoniae

16. Relationship Between Patient Types, Pulmonary Function, and Likely Pathogens Viral, allergens, pollutants, cigarette smoke M.pneumoniae, C.pneumoniae H.influenzae, S.pneumoniae FEV1 % Predicted Enterobacteriaceae Pseudomonas spp Gram-negatives Resistant organisms Acute Bronchitis Chronic Bronchitis Simple Complicated Complicated PLUS Risks

17. Respiratory Tract Infections • H.influenzae • Most common cause of AE-COPD-small gram negative bacilli-requires X and V factors for growth-will grow on “chocolate” agar (5% CO2)-may be encapsulated • Historically, type b (Hib) responsible for majority of invasive disease • Introduction of Hib vaccine >> very little Hib seen today • majority of mucosal disease due to non-encapsulated strains

18. Respiratory Tract Infections • Approx 20% produce -lactamase • < 2% have altered PBP • 2nd / 3rd generation cephalosporins effective • newer macrolides have some activity • fluoroquinolones very active, but contraindicated in children

19. Respiratory Tract Infections • Moraxella catarrhalissmall gram negative cocco-bacilliassociated with otitis media, sinusitis, AECBcarriage rate probably approaches 50% • 90% strains resistant to ampicillinwith exception of trimethoprim, predictably susceptible to most oral antibiotics

20. Respiratory Tract Infections • Bordetella pertussis • Causitive agent of pertussis • Small gram negative cocci-bacilli • Strictly aerobic, fastidious • Requires growth on media containing charcoal, blood, or starch • Bordet-Gengou(BG) or RL medium

21. Respiratory Tract Infections • Incubation period generally 7-10 days (range 4-21) • Classical course of disease:1. Catarrhal stage 1-2 weeks - symptoms non specific - low grade fever, mild cough, etc 2. Paroxysmal stage 1-6 weeks - paroxysmal cough, whoop, posttussive vomiting 3. convalescent stage 2-4 weeks - symptoms gradually decrease

22. Respiratory Tract Infections • Laboratory diagnosis • Naso-pharyngeal specimens best yield • - culture - PCR - DFA • Treatment - macrolides 1st choice

23. RTIs • Nosocomial pneumonia - ventilated patients at increased risk - gram negative bacteria / S.aureus • Nursing home pneumonia - similar etiology to CAP - greater incidence of anaerobes