Approach to Selecting the Appropriate Antibiotic

1. Approach to Selecting the Appropriate Antibiotic Teresa Lianne Beck, MD Assistant Professor Family Medicine Residency Program Adapted from Eddie Needham, MD with permission Emory University Physician Assistant Program

2. Objectives • Identify the appropriate 1st and 2nd line antibiotic for empiric treatment of common bacterial infections in the community and hospital settings • Tailor the choice of antibiotic based on unique patient risk factors • Identify EBM electronic resources for information on safe, effective treatment Emory University Physician Assistant Program

3. Basic Assumptions • Everyone knows who Jay Sanford was…as in Sanford’s Guide to treating infections • Everyone has an ID reference they carry with them • Epocrates ID, Griffith’s 5 minute consult… Emory University Physician Assistant Program

4. Basic Assumptions • Everyone will attempt to use when possible: • The least costly effective drug • Use Epocrates or a similar tool to check costs • A once or twice daily drug • The most safe drug with the least side effects and interactions • Use Epocrates drug interaction tool Emory University Physician Assistant Program

5. Basic Assumptions • Drug dosages are readily available • Sanford, Epocrates, Griffith’s 5MCC, etc… • Drug dosages change based on renal function and recent literature • New drugs are produced often • As such, I will not mention specific dosages unless appropriate for the discussion Emory University Physician Assistant Program

6. Principles on choosing an antibiotic for empiric therapy • As best possible, attempt to localize the site of infection • Do a good exam!!! • Occam’s razor • “Plurality must not be posited without necessity” • Use only one diagnosis whenever possible Emory University Physician Assistant Program

7. Classes • Bacteriostatic vs Bactericidal • Narrow vs Broad spectrum Emory University Physician Assistant Program

8. Classes • Bacteriostatic • Aminoglycosides (Streptomycin, Amikacin, Gentamicin, Tobramycin) • Lincosamides (Clindamycin) • Macrolides (Azithromycin) • Tetracyclines (Doxycycline) Emory University Physician Assistant Program

9. Bactericidal • Penicillins • Cephalosporins • Monobactams (Aztreonam) • Carbapenems (Meropenem) • Quinolones • Sulfonamides • Aminoglycosides • Glycopeptides (Vancomycin) • Lipopeptides (Daptomycin) • Nitrofurans • Metronidazole Emory University Physician Assistant Program

10. Broad Spectrum • Amoxicillin/clavulanate (Augmentin) • Ampicillin/sulbactam (Unasyn) • Piperacillin/tazobactam (Zosyn) • Ticarcillin/clavulanate (Timentin) Emory University Physician Assistant Program

11. Newer Classes • Cyclic lipopeptides (daptomycin) • Bactericidal against Gram-positive, including MRSA • Glycylcyclines (tigecycline) • Bacteriostatic against Gram-pos, Gram-neg and MRSA • Oxazolidinones (linezolid) • Bacteriostatic and bactericidal against Gram-positive, including MRSA, VRE Emory University Physician Assistant Program

12. Case 1 • 35 year old female presents to your clinic with c/o: • Dry cough x 7 days • Intermittent fevers, measured to 100.8 • Few URI sx • PMHx: Healthy, ran Peachtree 2 months ago, no meds Emory University Physician Assistant Program

13. Case 1 • PSHx – C-section for second child • Social – nonsmoker, 1-2 glasses wine per month, married 10 yrs – faithful, works as an accountant • FamHx – HTN, T2DM • Travel – none recent outside Georgia Emory University Physician Assistant Program

14. Case 1 What could this be? DDx? Emory University Physician Assistant Program

15. Case 1 • Exam • VS – temp 100.3, P 92, RR 18, Pulse Ox 96% on room air, BP 123/75 • HEENT – normal • Neck – normal w/o palpable LAD or TMG • Lungs – scattered inspiratory crackles in midlung fields, R>L, clear at bases, no EA changes (egophony) • CV – normal • Legs – no edema Emory University Physician Assistant Program

16. Case 1: Chest X-ray Emory University Physician Assistant Program

17. Emory University Physician Assistant Program

18. Case 1 – Diagnosis? • Community –acquired Pneumonia (CAP) • Can use the Pneumonia severity index calculator to help determine inpatient vs outpatient treatment • See List at end of presentation Emory University Physician Assistant Program

19. CAP • Common Outpatient Bacterial Etiologies • Streptococcus pneumonia • Mycoplasma pneumonia • Chlamydophila pneumonia • New and improved name Emory University Physician Assistant Program

20. The pneumococcus Emory University Physician Assistant Program

21. CAP – Outpatient Treatment • Antibiotics • Oral macrolide • Erythromycin • Azithromycin • Clarithromycin • Doxycycline • Be careful with potentially pregnant moms or fair-skinned patients who work in the sun. Emory University Physician Assistant Program

22. CAP – Outpatient Treatment • In patients who are older, have comorbid illnesses, or in communities with high pneumococcal resistance to penicillin, consider antipneumococcal fluoroquinolones: • Levofloxacin • Moxifloxacin • In patients previously treated with antibiotics within the previous 90 days, consider a fluoroquinolone. Emory University Physician Assistant Program

23. Streptococcal resistance • Nationally, <1% of isolates are resistant to fluoroquinolones. • This number can be higher is some urban centers, especially ICU settings. Emory University Physician Assistant Program

24. CAP – Inpatient Treatment Emory University Physician Assistant Program

25. CAP – Inpatient Setting • Common Inpatient Bacterial Etiologies • Streptococcus pneumonia • Hemophilis influenza • Klebsiella pneumonia • Staphlococcus aureus • Other gram-negative bacilli (GNRs) • Anaerobic mouth organisms Emory University Physician Assistant Program

26. CAP – Inpatient Treatment • Beta-lactam + macrolide • Ceftriaxone or cefotaxime + • Erythromycin, azithromycin, or clarithromycin or • Fluoroquinolone with antistreptococcal activity • Levofloxacin or moxifloxacin Emory University Physician Assistant Program

27. CAP – aspiration risk Emory University Physician Assistant Program

28. CAP – aspiration risk • Consider adding one of the following: • Metronidazole • Clindamycin • Reasonable alternatives include: • Moxifloxacin • Ampicillin-sulbactam Emory University Physician Assistant Program

29. CAP – ICU setting • Consult Infectious Diseases Emory University Physician Assistant Program

30. Tuberculosis • Don’t forget about TB, especially in the HIV and immigrant populations. • This is a whole talk in itself. • Guidelines for treatment in the back. Emory University Physician Assistant Program

31. Case 2 • 23 year old female presents with symptoms of dysuria and frequency. • Recently married – returned from honeymoon two weeks ago. • Previously healthy with no significant FamHx. • Uses no medications and has NKDA. Emory University Physician Assistant Program

32. Case 2 Diagnosis? Emory University Physician Assistant Program

33. Case 2 • The urinalysis confirms a UTI. • What else do you want to know? • No fevers • No CVAT – to r/o pyelonephritis. Emory University Physician Assistant Program

34. UTI • Common bacteria (is there more than one?): • E. coli • Second most common bacteria is… • Staphylococcus saprophyticus • Others are: • Proteus spp. • GNRs Emory University Physician Assistant Program

35. UTI - Treatment • Trimethoprim/sulfamethoxizole x 3 days • With high resistance or in women with risk factors, consider: • Fluoroquinolone x 3 days: • Ciprofloxacin • Norfloxacin • Ofloxacin, or • Nitrofurantoin x 7 days Emory University Physician Assistant Program

36. Pyelonephritis • Initial drug selections: • Fluoroquinolones • Ciprofloxacin • Levofloxacin • Beta-lactam • Ceftriaxone • Cefotaxime • Ampicillin-sulbactam Emory University Physician Assistant Program

37. Case 3 • 57 yo male went fishing five days ago and slipped on a rock, cutting his leg. Leg is now red and moderately painful. Slight subjective fevers at home, per his wife. • PMHx – COPD, high cholesterol • Social – stopped tobacco two years ago, works in retail business – men’s clothing Emory University Physician Assistant Program

38. Case 3 • Exam • Temp 101.2 otherwise stable • Exam unremarkable except for: • Lungs – few inspiratory rales, at his baseline per your previous exams • Right leg … Emory University Physician Assistant Program

39. Case 3 – Leg Exam Emory University Physician Assistant Program

40. Case 3 – Admit or not Admit? Audience poll now ensues  Emory University Physician Assistant Program

41. Cellulitis – reasons to admit • Failed outpatient therapy • Toxic appearing • High fevers • Low BP • This was a common cause of “blood poisoning” • Potential abscess formation in “difficult” location • Poor social situation/follow up lacking • Consideration of bad bacteria, eg. Pseudomonas Emory University Physician Assistant Program

42. Cellulitis • Common bacterial organisms • Streptococcus spp. • S. pyogenes (group A) or S. agalactiae (group B) • Staphylococcus aureus • Complicated skin infections • Think polymicrobial, in addition to above: • GNRs – E. coli, P. aeruginosa • Clostridium spp. Emory University Physician Assistant Program

43. Cellulitis - uncomplicated • Outpatient Treatment: non-MRSA • Antistaphylococcal penicillins: • Dicloxacillin • First-generation cephalosporin • Cephalexin • Inpatient Treatment: non-MRSA • Nafcillin • Cefazolin • Clindamycin is a good alternate with penicillin allergy Emory University Physician Assistant Program

44. Bad cellulitis, A.K.A…? Emory University Physician Assistant Program

45. Another version of …? Emory University Physician Assistant Program

46. Necrotizing cellulitis or fasciitis • Increasing causes include: • Group A streptococcus • Methicillin resistant Staph. aureus Emory University Physician Assistant Program

47. Cellulitis – complicated, non-MRSA • Drug choices include: • Piperacillin/tazobactam • Ticarcillin/clavulanate • Imipenem • Meropenem • Consider surgical debridement Emory University Physician Assistant Program

48. MRSA • Most predominant cause of suppurative skin infections in many parts of the USA • Consider if: • Patient recently treated with antibiotics • Patient known to be colonized • Patient recently hospitalized • Geographic area of high prevalence • In areas of high rates of Community-acquired MRSA (CA-MRSA), risk factors do not need to be present Emory University Physician Assistant Program

49. MRSA Emory University Physician Assistant Program

50. MRSA - Treatment • Outpatient • Trimethoprim/sulfamethoxizole • Clindamycin • Doxycycline • Not fluoroquinolines – increasing resistance • Local debridement Emory University Physician Assistant Program