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The ABC’s of Infections

The ABC’s of Infections. Eleana M. Zamora, MD Department of Internal Medicine Division of Pulmonary/Critical Care/Sleep. Objectives. Understand the difference between nosocomial and community-acquired Know where to find antibiogram data

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The ABC’s of Infections

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  1. The ABC’s of Infections Eleana M. Zamora, MD Department of Internal Medicine Division of Pulmonary/Critical Care/Sleep

  2. Objectives • Understand the difference between nosocomial and community-acquired • Know where to find antibiogram data • Have a basic understanding of how to approach common infections in the inpatient and outpatient setting

  3. Overview • Community vs. nosocomial • Upper/Lower respiratory infections • C.difficile-associated diarrhea • Intra-abdominal infections • Skin-soft tissue infections • Bacteremia • Osteomyelitis, septic joints

  4. Gram positives

  5. Gram negatives

  6. Urine Antibiogram

  7. Objectives: Crash Course • Commonly encountered infections in inpatient and outpatient settings • What bugs? • What drugs? • Common clinical syndromes

  8. Community vs. Nosocomial • Why important? • Atypicals • MDRO • MRSA • Pseudomonas • Broadened definition of “nosocomial” • SNF, OPAT, jail, community-living, homeless, etc.

  9. Common Outpatient Infections • Upper respiratory • Lower respiratory • Sinusitis • Pharyngitis • UTI • SST

  10. Upper Respiratory Infection • Def’n: • Acute infxn which is typically viral • Sinus, pharngeal, or lower airway symptoms may be present, but are not prominent • Abx are rarely indicated • Although most “colds” have sinus symptoms, less than 2% have complication of acute bacterial sinusitis • Presence of green mucus does not necessarily indicate bacterial infection

  11. Acute Pharyngitis • GAS causes 10% of adult pharyngitis • 90% are NOT GAS! • DDx: EBV, CMV (less likely), gonococcus, HSV, HIV, Syphilis • ABX are rarely indicated for routine pharyngitis • Use the Centor diagnostic criteria to decide who to test • Treat only positive GAS rapid screens or patients who have all 4 criteria

  12. Centor Criteria • History of fever • Tonsillar exudates • No cough • Tender anterior cervical LAD ≥2 of the above = treat

  13. Treatment of GAS Pharyngitis • Treatment of choice: Penicillin V 500mg BID or 250mg QID x 10 days • Alternatives • Benzathine PCN 1.2 MU IM x 1 dose (for noncompliant patients) • 2nd gen cephalosporin: cefuroxime or cefprozil 500 mg qday, etc. etc • Azithro 500mg x1, then 250mg po day x 4d • If macrolide failure or pcn-allergy: FQ • Bactrim does not cover GAS

  14. Acute Sinusitis • Most cases of sinusitis are viral • Bacterial rhinosinusitis • Sxlasting ≥7 d who have maxillary pain or tenderness in the face or teeth (esp. unilateral) and purulent nasal secretions • Severe dz: dramatic symptoms of severe unilateral maxillary pain, swelling, and fever.

  15. Sinusitis Guidelines: IDSA 2012

  16. IDSA: Treatment • First line = B-lactam (amox/clav) • Preferred over respiratory FQ • Doxycycline is equivalent to amox/clav • Not recommended to cover for MRSA • Not recommended for use: • Macrolides, Bactrim • Duration of tx: 5-7 days • Recommended over 10-14 days

  17. Acute Sinusitis • Etiology • Community-acquired from obstruction of ostia, allergens, post-viral infxn: • S.pneumo 31% • H.influenzae 21% • M.catarrhalis 10% • S.aureus 4% • Diabetic, neutropenic, IV iron therapy: • mucor/rhizopus, aspergillus

  18. Etiology of Acute Sinusitis • Nosocomial , NGT, or nasal intubation: • Gram neg (pseudomonas, acinetobacter) 47% • Staph aureus/gram pos 35% • Yeast 18% • Polymicrobial 80%

  19. Chronic Sinusitis • Pathogenesis is multifactorial • Smoking • Nasal polyps • Periodontitis • Antibiotics are rarely effective • Refer to ENT • STOP SMOKING! • Atypical pathogens • Prevotella, anaerobes, fusobacterium, Pseudomonas, fungi/molds

  20. URI

  21. Non-Specific URI • Resistant Strep pneumoniae • outpatient abx • Treating a viral URI with abx directly increases the risk of resistant bug transmission • Upper URI account for over 75% of outpatient RX each year

  22. For URI Syndromes: Very strongly consider NOabx: ABX should be used for: Documented GAS pharyngitis Severe sinusitis with fever, ptosis, etc. Pneumonia (LRI) • Adult uncomplicated acute bronchitis • Not acute exacerbations of chronic bronchitis) • Acute sinusitis • Pharyngitis • Nonspecific URI

  23. WHATUP! Lower Respiratory

  24. Lower Respiratory Infections • Tracheitis – biggest airways • Bronchitis –large airways • Bronchiolitis – smallest airways, wheezing • Pneumonia – air space infection • Basic concepts are the same for all

  25. Stepwise Approach • Decide viral, bacterial, atypical, other? • Not always so easy…sometimes more than one • Rule of thumb: cover the top 3 • Risk factors • Smoking, travel, immunosuppression, diabetes

  26. Pseudomonas? • Community-acquired vs. nosocomial +/- aspiration • Hospitalized vs. non-hospitalized • Remember new broader risk categories for MDRO • Pseudomonas and Acinetobacter longer duration of tx

  27. Powers of Pseudomonas Prediction

  28. Common CAP Etiologies IDSA CAP Guidelines 2007

  29. Outpatient CAP Tx

  30. To Hospitalize or not? • Pneumonia severity index (PSI) • CURB-65 • Your gut feeling counts • CURB-65 • Confusion, Uremia, RR, low BP, age>65 • Score > 2admit

  31. Severe CAP • IDSA Guidelines 2007

  32. Inpatient, non-ICU CAP Tx • UNMH Formulary • Ceftriaxone + azithromycin/doxy • If β-lactam allergy: moxifloxacin • Moxi not for UTI or Pseudomonas

  33. Inpatient CAP, ICU • UNMH Formulary • Ceftriaxone + azithromycin • Not doxy • If β-lactam allergy: moxifloxacin

  34. Pseudomonal Risk Factors • UNM: Know the antibiogram! • Available to you without ID consult: Zosyn (87%S), Cefepime (82%), Cipro (72%), Gent/Tobra (85%) • ID Consult only: Meropenem (95%), amikacin (89%), doripenem, colistin

  35. Infectious Diarrhea

  36. Clostridium difficile • SHEA/IDSA Guidelines 2010 • Who to test? • What to do? • How to treat? • When to take out of isolation?

  37. The New CDAD • 4 x’s increase in cases over 13 year period • Increase in disease severity • Major risk factors for NAP1 strain • Age > 65 • Recent use of FQs

  38. ≥2 points classified as severe 1 point given for each of the following: Age > 60 Temp >38.3 WBC > 15K Albumin < 2.5mg/dL 2 points for endoscopic evidence of CDAD (Alternate: AKI) (Alternate: sepsis, ICU) Severity assessment score

  39. Case Definition • Presence of diarrhea (>3 unformed stools in 24 hours) • Stool test positive for Cdiff or its toxins • Colonoscopic evidence of Cdifficile

  40. Who to test? • Anyone with diarrhea? • Do not test asymptomatic patients • Only patients with diarrhea, not formed • Unless toxic megacolon/ileus • High risk: • SNF, jail, group home • Recent (<90d) abx • Recent (<30d) hospitalization • Known contact (2-3 days avg) • Severe, ICU intraabdominal source suspected

  41. What test? • Previously used test for toxin • UNMH uses PCR confirmation • A single test per episode of diarrheal illness is recommended • No more than one test every 7 days • Do not need multiple tests to “rule-out” • Do not need test of cure

  42. Understanding the test • Stool tested for Antigen (Ag) and toxin (T) • Ag (+) T (+)  positive C.diff (red) • Ag (+) T (-)  reflex to PCR (red) • Ag (-) T (+)  reflex to PCR (red) • Ag (-) T (-) negative C.diff

  43. What to do? • If you think it, patient must be in isolation • NEVER EVER order the test without putting patient in isolation at same time • Never treat empirically without putting in isolation at same time • If patient is ill, empiric tx is ok

  44. Consider calling general surgery for severe disease! How to treat?

  45. Intra-Abdominal

  46. Complicated Intra-abdominal Infections • Examples: • Perfdiverticulum • Complicated GB infection • Abscess • Peritonitis • Location matters • Flora of upper small bowel vs. from beyond small bowel vs. from beyond ileum vs. rectum

  47. It’s All About Location! • Upper GI, duodenum, biliary system, proximal small bowel • Peritonitis common • Gram pos, gram neg aerobic and facultative organisms • Enterococcus is not a real concern • Distal small bowel • Less GPC, more GNR (aerobes, facultative) • Often evolve into abscesses (not peritonitis)

  48. Location, location, location • Colon • Facultative (E.coli) and obligate anaerobes (B.frag), Streptococci (S.bovis) • Abscesses • Abscesses, in general, should be drained • ABX have hard time getting into abscess • Exception? • ALWAYS send aspirate for anaerobic/aerobic culture

  49. So, Why So Complicated? • Location • Some drugs are inactive in abscesses • Some drugs are pH dependent • Bugs • Some bugs are resistant • B.frag vs. clinda/fq/cefotetan/cefoxitin • Community-Acquired vs. Nosocomial? • Pseudomonas is less common in abscesses

  50. Who to Treat? • Bowel trauma that get surgically repaired within 12 hours, upper GI perf in the absence of antacids, or acute appendicitis • Abx used for <24h • Acute uncomplicated cholecystitis = NO • Ascending cholangitis = YES • Acute pancreatitis = NO • Necrotizing pancreatitis = YES

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