infectious disease

INFECTIOUS DISEASE ANTIMICROBIAL REVIEW Michelle Aguirre Janel - PowerPoint PPT Presentation

INFECTIOUS DISEASE ANTIMICROBIAL REVIEW Michelle Aguirre Janel Liane Cala PGY1 Pharmacy Practice Residents Medical Center Hospital Objectives Review basic microbiology of organisms Implement MCH Antibiogram utilization Define

  1. INFECTIOUS DISEASE ANTIMICROBIAL REVIEW Michelle Aguirre Janel Liane Cala PGY1 Pharmacy Practice Residents Medical Center Hospital

  2. Objectives • Review basic microbiology of organisms • Implement MCH Antibiogram utilization • Define minimum inhibitory concentration (MIC) • Discuss resistant drug organisms and treatment • Identify risk factors for common multi-drug resistant pathogens


  4. Bacterial Morphology

  5. Gram Staining organisms/gram-staining.html


  7. MCH Antibiogram • Printed each year based on previous year’s laboratory data for critical care and medical floors • Provided by pharmacy department and the antimicrobial stewardship program • Should be reviewed and used to determine proper empiric therapy based on most common organisms seen in different types of infections

  8. MIC Interpretation • MIC: minimum inhibitory concentration • Lowest concentration of an antibiotic that inhibits the growth of a given strain of bacteria • Susceptibility Interpretation • S (sensitive): organism is inhibited by the serum concentration of the drug that is achieved using recommended dosage • I (intermediate): isolates with MICs that approach usually attainable blood and tissue levels and for which response rates may be lower than for susceptible strains • R (resistant): resistant to the usually achievable serum drug levels

  9. Case Question • VE is a 44-year-old man who was admitted for an abscess. He was started on empiric therapy with pipercillin/tazobactam and vancomycin. Which de-escalation is appropriate based on the following susceptibilities?


  11. Pop Quiz • Is it MSSA or MRSA?

  12. Methicillin Sensitive Staph Aureus (MSSA) • Coagulase (+) • Catalase (+) • Oxacillin sensitive • SSTI, PNA, Meningitis, Endocarditis, Osteomyelitis • 1 st Line: • Penicillinase-resistant Penicillin (Nafcillin, Oxacillin) • 1 st Generation Cephalosporins (Cefadroxil, Cefazolin, Cephalexin) • Alternatives: • Clindamycin, Vancomycin, Tetracycline, Sulfamethoxazole-trimethoprim

  13. Methicillin Resistant Staph Aureus (MRSA) • Coagulase (+) • Catalase (+) • Oxacillin resistant • SSTI, PNA, Meningitis, Endocarditis, Osteomyelitis • 1 st line: Vancomycin (MIC ≥2  switch agent) • Alternatives • Daptomycin (not for PNA) • Linezolid (for SSTI, PNA) • Tigecycline (not for bacteremia) • Ceftaroline

  14. Methicillin Resistant Staph Aureus (MRSA) Table 1. MRSA Treatment Options Oral Treatment IV Treatment TMP-SMX* Vancomycin Clindamycin* Linezolid Doxycycline, minocycline* Daptomycin Linezolid Ceftaroline Tigecycline ᵃ Quinupristin-dalfopristin ᵃ Dalbavancin, oritavancin *for Community Acquired MRSA (CA-MRSA) ᵃSalvage therapy

  15. Vancomycin, Daptomycin, and Linezolid • All active against gram-positive cocci, including MRSA Table 2. Gram-Positive Drug Class Overview Agent Adverse reactions Pearls Vancomycin Infusion reactions, renal MIC ≥ 2 associated with toxicity (not contraindicated treatment failure in AKI), ototoxicity (rare) Do not use in MSSA infections (unless penicillin allergy) Daptomycin CPK elevation (obtain Inactivated by pulmonary surfactant  do not use for baseline and monitor weekly) pneumonia Linezolid Bone marrow suppression, Long-term therapy increases risk peripheral neuropathy, optic of AE’s neuritis, lactic acidosis Not ideal in UTIs (~30% excreted in urine)

  16. Case Question • A 33-year-old obese man with a history of recurrent skin abscesses due to MRSA presents to the emergency department with a productive cough, pleuritic chest pain, and dyspnea. One week ago he had influenza. Chest radiography shows multilobar infiltrates and early cavitation. A sputum Gram stain shows numerous gram-positive cocci in clusters. • The sputum culture grows S. aureus, which is resistant to oxacillin, has MIC of 6 to vancomycin, and greater than 4 to clindamycin and which are susceptible to daptomycin, linezolid, and quinupristin/dalfopristin.

  17. Case Question (continued) • Which one of the following antimicrobial regimens would be the best treatment for this patient’s infection? Daptomycin 6 mg/kg intravenously once daily a) b) Linezolid 600 mg intravenously twice daily Vancomycin 1 g intravenously twice daily c) d) Ceftriaxone (1 g/d intravenously) plus azithromycin (500 mg/d intravenously) Vancomycin (15-20 mg/kg intravenously twice daily) to e) achieve a trough concentration of 10 to 15 µg/mL plus clindamycin (600 mg intravenously every 8 hours)

  18. Enterococcus • Gram-positive bacteria in short chains (may appear as streptococcus in pairs/chains in gram-stain report) • Present in normal colonic flora, oropharyngeal and vaginal secretions • Usually a nosocomial, opportunistic pathogen E. faecalis E. faecium More common Less common Highly virulent Less virulence More resistance  VRE Less resistance • Vancomycin is the drug of choice for empiric coverage • Ampicillin is the drug of choice for enterococcus if susceptible

  19. Vancomycin-Resistant Enterococcus Table 4. Usual treatment options based on species VRE (E. Faecalis) VRE (E. Faecium) Pen G or ampicillin Daptomycin Linezolid Linezolid Daptomycin Quinipristin/dalfopristin* Tigecycline Tigecycline Fluoroquinolones Cyctitis only: fosfomycin, Cystitis only: nitrofurantoin, doxycycline fosfomycin, doxycycline *Active against E. faecium but not E. faecalis; salvage therapy

  20. Pseudomonas aeruginosa • Gram-negative, non-fermenting rod • Usually a nosocomial, opportunistic pathogen • Usual infections • Respiratory: pneumonia • GU: UTI/pyelonephritis • CV: endocarditis, bacteremia, sepsis • Skin/bone: cellulitis, osteomyelitis • Risk factors: • Immunosuppression, diabetes mellitus, cystic fibrosis, neutropenia, AIDS

  21. Treatment Options for Pseudomonas Betalactams Aminoglycosides Fluoroquinolones Polymyxin PCN Amikacin Ciprofloxacin 400 mg Colistin -Piperacillin/ Tazobactam 8 mg/kg THEN q8h 5mg/kg x1 7.5 mg/kg q12h Levofloxacin 750 mg THEN Cephalosporins q24 2.5mg/kg q12 Ceftazidime 2g q8 Gentamicin/ Cefepime 1-2g q8 Tobramycin Polymyxin B Ceftazidime/Avibactam 2.5g 3 mg/kg THEN 1.25 mg/kg q12 q8h 2 mg/kg q8h Ceftolozane/tazobactam 1.5g q8h Carbapenems Imipenem/Cilastatin 1g q8h OTHER: Meropenem 1g q8h Fosfomycin 3g Doripenem 500mg q8h PO x 1 Monobactam Aztreonam 2g IV q8h

  22. Pop Quiz Patient on piperacillin/tazobactam for 4 days treating HAP and WBC 25, febrile, requiring pressors. Which intravenous antimicrobial agents would be appropriate for a patient with this susceptibility report? A. Piperacillin/tazobactam Aztreonam B. Cefepime C. D. Meropenem

  23. Acinetobacter • Gram negative, strictly aerobic, nonmotile, coccobacilli • Commonly found in: soil, water, catheters, ventilation equipment • Usual types of infection: PNA, Septicemia, Burn Wounds • Risk factors: • Immunosuppression • Burns • Medical devices (central line, catheter, ventilator, endoscopes, feeding tubes) • Previous antibiotic exposure

  24. Acinetobacter treatment • Imipenem 0.5-1gm IV q6h • Meropenem 0.5-2 gm IV q 8h • Ampicillin/ Sulbactam 3g (2:1) q6h • Tigecycline 100 mg IV, then 50 mg IV q 12 h • Pan-resistant isolates: • Colistin + any of the above • Variable activity  AMG, Cephalosporins, Minocycline, Rifampin, TMP/SMX

  25. STENOTROPHOMONAS MALTOPHILIA • Aerobic, gram negative bacillus with polar flagella • Found mostly in aquatic environment, plants, soil; frequent colonizer of body fluids • Nosocomial sources: dH2O, nebulizers, dialysates, contaminated disinfectants • Low virulence  mostly affects immunocompromised • Risk factors: • Foreign bodies (catheters) • Neutropenia • Broad spectrum abx • CF

  26. STENOTROPHOMONAS MALTOPHILIA Trimethoprim/sulfamethoxazole 15mg/kg/day divided in 2 to 3 doses Ticarcillin/clavulanate 3.1 g q6h IV Ampicillin/ sulbactam 3 g q6h IV Ceftazidime 2 g q8h IV Ciprofloxacin 400 mg q8-12h IV Levofloxacin 500-750 mg q24h IV Moxifloxacin 400mg/day Doxycycline 100 mg q12h IV Colistin (MDR) + COMBI 2.5 mg/kg q12

  27. ESBL (Extended Spectrum Betalactamase)

  28. ESBL (Extended Spectrum Betalactamase)

  29. • Carbapenems- similar outcomes and mortality within class • Ceftolozane- Tazobactam** RENAL IAI  1.5g q8h 4-14d + Metronidazole  • cUTI  1.5g q8h x 7days (at least**) • • Ceftazidime-avibactam** RENAL IAI  2.5g q8h 5-14d + Metronidazole • cUTI  2.5g q8h x 7days (at least**)- 14d • • Cefepime 2g q8h – variable; not suggested; inferior to carbapenem • Piperacillin- Tazobactam- variable; not recommended • Fluoroquinolones- Cipro  • Uncomplicated UTI- Fosfomycin, Nitrofurantoin, Bactrim

  30. Pop Quiz • JW is a patient who is being seen for an intra-abdominal ESBL infection. In addition, he has a history of poorly controlled seizures for which he takes several antiepileptic drugs. Which of the following carbapenems would you avoid the most in this patient? Ertapenem a) b) Meropenem Imipenem/cilastin c) d) Doripenem


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