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Antibiotic Monotherapy for Intraabdominal Infections IS BROAD SPECTRUM MONOTHERAPY ANTIBIOTIC TREATMENT ADEQUATE FOR INTRAABDOMINAL INFECTIONS ? Nicolas V. Christou Associate Professor of Surgery and Microbiology McGill University
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Antibiotic Monotherapy for Intraabdominal Infections DIAGNOSIS OF INTRA-ABDOMINAL INFECTION History & Physical Examination Laboratory Tests Imaging techniques
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Antibiotic Monotherapy for Intraabdominal Infections OUTLINE Basic principles Review of antibiotic choices Presentation of most recent data on monotherapy Conclusions
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Antibiotic Monotherapy for Intraabdominal Infections MORTALITY OF INTRA-ABDOMINAL INFECTIONS Localized Abscess Localized Peritonitis Diffuse Suppurative Peritonitis Combined Complicated Infection Mortality %
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Antibiotic Monotherapy for Intraabdominal Infections TREATMENT OF INTRA-ABDOMINAL INFECTIONS Surgical drainage and correction of pathology broad spectrum EMPIRIC antibiotic therapy
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Antibiotic Monotherapy for Intraabdominal Infections ANTIBIOTIC THERAPY OF SURGICAL INFECTIONS Empiric Antibiotic Therapy: A single antibiotic or a combination of antibiotics providing BROAD SPECTRUM coverage against all possible pathogens. Definitive Antibiotic Therapy: Antibiotic administration based on specific culture and sensitivity results.
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Antibiotic Monotherapy for Intraabdominal Infections HOW DOES ONE PICK APPROPRIATE EMPIRIC ANTIBIOTIC THERAPY ? Use an antibiotic or combination of antibiotics that provides broad spectrum activity to cover all suspected PATHOGENS.
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Antibiotic Monotherapy for Intraabdominal Infections SUSPECTED PATHOGENS IN INTRA-ABDOMINAL INFECTIONS E. coli (59%) K. pneumonia (11%) P. aeruginosa (5%) Enterobacter (5%) P. mirabilis (4%) Other (16%) Gm -ve AEROBES RVH Data
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Antibiotic Monotherapy for Intraabdominal Infections SUSPECTED PATHOGENS IN INTRA-ABDOMINAL INFECTIONS Gm +ve AEROBES Enterococcus (55%)S. aureus (25%) Corynebacteria (10%) S. epidermidis (6%) Others (4%) RVH Data
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Antibiotic Monotherapy for Intraabdominal Infections SUSPECTED PATHOGENS IN INTRA-ABDOMINAL INFECTIONS ANAEROBES Bacteroidis sp. (57%) B. fragilis (27%) Fusobacteria (6%) Others (9%) RVH Data
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Antibiotic Monotherapy for Intraabdominal Infections ANTIBIOTICS FOR SURGICAL INFECTIONS Penicillins Aminoglycosides Cephalosporins Metronidazole Carbapenems Clindamycin Quinolonnes Vancomycin
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Antibiotic Monotherapy for Intraabdominal Infections PENICILLINS Basic structure of Penicillins Penicillin G Methicillin Cloxacillin Carboxipenicillins Ureidopenicillins (Penem nucleus)
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Antibiotic Monotherapy for Intraabdominal Infections In vitro ACTIVITY of PIPERACILLIN Minimal Inhibitory Concentration (MIC in µg/ml) of Antibiotic 90
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Antibiotic Monotherapy for Intraabdominal Infections ANTIBIOTICS FOR SURGICAL INFECTIONS "More Recent" therapy UreidoPenicillin (Antianaerobic Agent) UreidoPenicillin (Antianaerobic Agent) eg Piperacillin 1-2 g q8h (eg Clindamycin 600 mg q8h)
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Antibiotic Monotherapy for Intraabdominal Infections AMINOGLYCOSIDES Gentamycin Tobramycin Netilmicin Amikacin Excellent Gm- activity (gentamycin)
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Antibiotic Monotherapy for Intraabdominal Infections In vitro Activity of Aminoglycosides - GENTAMYCIN Minimal Inhibitory Concentration (MIC in µg/ml) of Antibiotic 90
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Antibiotic Monotherapy for Intraabdominal Infections ANTIBIOTICS FOR SURGICAL INFECTIONS "Gold Standard" therapy Aminoglycoside + Antianaerobic Agent Aminoglycoside + Antianaerobic Agent eg Gentamycin 2-3 mg/kg q8h eg Clindamycin 600 mg q8h
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Antibiotic Monotherapy for Intraabdominal Infections Aminoglycoside Use - Caution Ototoxicity Nephrotoxicity Occurs in up to 30% of cases and often is not reversible. Occurs in up to 5% of cases and is often reversible.
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Antibiotic Monotherapy for Intraabdominal Infections CEPHALOSPORINS Penam nucleus Cephem nucleus R R1 First Generation Second Generation Third Generation eg. Cephazolin eg. Cefoxitin eg. Cefotaxime
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Antibiotic Monotherapy for Intraabdominal Infections In vitro ACTIVITY of 2nd GENERATION CEPHALOSPORINS - CEFOXITIN Minimal Inhibitory Concentration (MIC in µg/ml) of Antibiotic 90
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Antibiotic Monotherapy for Intraabdominal Infections In vitro ACTIVITY of 3rd GENERATION CEPHALOSPORINS - CEFOTAXIME Minimal Inhibitory Concentration (MIC in µg/ml) of Antibiotic 90
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Antibiotic Monotherapy for Intraabdominal Infections ANTIBIOTICS FOR SURGICAL INFECTIONS "More Recent" therapy 3 Generation Cephalosporin + Antianaerobic Agent 3 Generation Cephalosporin + Antianaerobic Agent eg Cefoperazone 1-2 g q12h eg Clindamycin 600 mg q8h rd
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Antibiotic Monotherapy for Intraabdominal Infections QUINOLONES Basic Structure of Quinolones Classified according to modifications at X2 and X8 positions. "True Quinolones" Norfloxacin Ciprofloxacin Enoxacin Perfloxacin Ofloxacin
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Antibiotic Monotherapy for Intraabdominal Infections In vitro activity of QUINOLONES Minimal Inhibitory Concentration (MIC in µg/ml) of Antibiotic 90
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Antibiotic Monotherapy for Intraabdominal Infections ANTIBIOTIC "EFFICACY" STUDIES: INTRAABDOMINAL INFECTIONS Cephalosporin based Rx Aminoglycoside based Rx Success Rate % 52-96% range 61-95% range
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Antibiotic Monotherapy for Intraabdominal Infections ANTIBIOTIC "EFFICACY" STUDIES: INTRAABDOMINAL INFECTIONS Problems in Study Design exclusion criteria not rigid lack of "illness stratification" results reporting
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Antibiotic Monotherapy for Intraabdominal Infections CARBAPENEMS Imipenem - approved for use Meropenem - phase III clinical trials
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Antibiotic Monotherapy for Intraabdominal Infections In vitro activity of IMIPENEM Minimal Inhibitory Concentration (MIC in µg/ml) of Antibiotic 90
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Antibiotic Monotherapy for Intraabdominal Infections COMPARATIVE ACTIVITIES OF VARIOUS ANTIBIOTICS MIC (90) µg/ml Enterobacter cloacae Acinetobacter calcoaceticus P. aeruginosa S. faecalis
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Antibiotic Monotherapy for Intraabdominal Infections A Multicenter Comparative Trial of Imipenem/Cilastatin vs Tobramycin/Clindamycin for Intraabdominal Infections 290 Patients Entered 143 - Tobra/Clinda 147 - Imipenem 81 Patients Evaluable Prospective, randomized, open design
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Antibiotic Monotherapy for Intraabdominal Infections Statistical Considerations Assumed failure rate = 25% Assumed nonevaluability rate = 30% Sample size to detect a 50% difference in outcome with =.05 and ß =.20 Adequate sample size: n=300 Logistic Regression Analysis, X, and Student's t-tests 2
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Antibiotic Monotherapy for Intraabdominal Infections Criteria for Eligibility > 18 years No drug hypersensitivity Normal renal function Suspected Intraabdominal Infection
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Antibiotic Monotherapy for Intraabdominal Infections Criteria for Exclusion Simple Appendicitis Simple Cholecystitis Traumatic bowel perforation < 12h Perforated peptic ulcer < 24 h Exploration with negative bacterial cultures
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Antibiotic Monotherapy for Intraabdominal Infections Reasons for Exclusion of 128 Patients Number of Patients
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Antibiotic Monotherapy for Intraabdominal Infections "ILLNESS" STRATIFICATION APACHE II % Mortality APACHE II Ranges A severity of disease classification system based on acute and chronic physiologic response variables such as : Pulse, Pressure etc Oxygenation, pH Glascow Coma Scale
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Antibiotic Monotherapy for Intraabdominal Infections Drug Therapy Imipenem/Cilastatin 500 mg i.v. q6h Tobramycin 1.5 mg/kg i.v. with interval adjusted for serum creatinine, Tobramycin levels aimed at : peak > 6 µg/ml and trough < 2 µg/ml Clindamycin 600 mg i.v. q8h +
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Antibiotic Monotherapy for Intraabdominal Infections Outcome Scoring Local Intra-abdominal Infection Hospitalization
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Antibiotic Monotherapy for Intraabdominal Infections Definition of Rx Success Initial study driven antibiotic therapy and an adequate operation cured the intraabdominal infection.
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Antibiotic Monotherapy for Intraabdominal Infections Definition of Rx Failure Survival of < 7 days Second intervention showed recurrence with initial organisms Wound Infection developed
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Antibiotic Monotherapy for Intraabdominal Infections Demographics of Evaluable Patients - I Tobra/ClindaImipenem Sex (M:F)49:3251:30 Age <502333 50-591016 60-692413 70-791713 >7976
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Antibiotic Monotherapy for Intraabdominal Infections Demographics of Evaluable Patients -II Number of Patients
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Antibiotic Monotherapy for Intraabdominal Infections Disease Processes Encountered at Initial Operation Number of Patients
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Antibiotic Monotherapy for Intraabdominal Infections Mean APACHE II Scores Encountered at Admission Mean APACHE II Score
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Antibiotic Monotherapy for Intraabdominal Infections Organisms Encountered in Intra-Abdominal Foci Number of Patients Gm -ve aerobes
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Antibiotic Monotherapy for Intraabdominal Infections Organisms Encountered in Intra-Abdominal Foci Number of Patients Gm +ve aerobes
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Antibiotic Monotherapy for Intraabdominal Infections Organisms Encountered in Intra-Abdominal Foci Number of Patients Anaerobes
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Antibiotic Monotherapy for Intraabdominal Infections Microbiologic Patterns of Encountered Infections Number of Patients
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Antibiotic Monotherapy for Intraabdominal Infections Activity of Study Agents: Gm-ve Bacteria MIC (µg/ml) of Antibiotic 90
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Antibiotic Monotherapy for Intraabdominal Infections Activity of Study Agents: Anaerobic Bacteria MIC (µg/ml) of Antibiotic 90
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Antibiotic Monotherapy for Intraabdominal Infections Overall Deaths, Failures and Predicted Deaths Failures Deaths Predicted APACHE II Range # Enrolled2439363618 # patients
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Antibiotic Monotherapy for Intraabdominal Infections Analysis of Deaths - I # Patients
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Antibiotic Monotherapy for Intraabdominal Infections Analysis of Deaths - II APACHE II Score
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Antibiotic Monotherapy for Intraabdominal Infections Analysis of Deaths - III Survival Time (days)
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Antibiotic Monotherapy for Intraabdominal Infections Failure as a Function of APACHE II and Antibiotic Regimen: All Patients Tobra/Clinda Imipenem X = 4.1 p=0.0429 Cumulative Failures APACHE II Score 2
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Antibiotic Monotherapy for Intraabdominal Infections Failure as a Function of APACHE II and Antibiotic Regimen: Gm-ve Organisms Tobra/Clinda Imipenem X = 5.65 p=0.0175 Cumulative Failures APACHE II Score 2
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Antibiotic Monotherapy for Intraabdominal Infections Reasons for Failure # Failures
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Antibiotic Monotherapy for Intraabdominal Infections Tobramycin Levels SuccessesFailures Peak Maximum6.4 + 1.96.1 + 1.7 Days to Max Peak3.8 + 2.64.6 + 5.2 (µg/ml + sd) (days + sd) - - - - - - Variable times to adequate Tobramycin levels
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Antibiotic Monotherapy for Intraabdominal Infections Data in support of MONOTHERAPY for surgical infections Results of a Multicenter Trial Comparing Imipenem/Cilastatin to Tobramycin/Clindamycin for Intra-abdominal Infections. Solomkin JS, Dellinger EP, Christou NV, Busuttil RW Ann. Surg 212:581-591, 1990. Imipenem vs Tobramycin-Antianaerobe Antibiotic therapy in Intra-abdominal Infections. Poenaru D, De Santis M, Christou NV Can. J. Surg. 33:415-422, 1990.
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Antibiotic Monotherapy for Intraabdominal Infections ANTIBIOTIC OF CHOICE FOR INTA-ABDOMINAL INFECTIONS Carbapenem MonoRx Carbapenem MonoRx eg Imipenem 500 mg q6h
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