Presented by Dr. Jenkins at the 40th Annual Symposium "Diagnostic and Clinical Challenges of 20th Century Microbes", held on Nov 18, 2010 in Philadelphia.

1. Recent Changes in Gram-negative Resistance: Algorithms for Detection and Reporting of ESBL, AmpC, and KPC – producing Organisms Stephen G. Jenkins, Ph.D. Director, Clinical Microbiology Laboratories New York/Presbyterian Hospital Weill Cornell Medical Center Professor of Pathology and Laboratory Medicine Professor of Medicine in Infectious Diseases Weill Cornell Medical College New York, NY

5. Class A, Chromosomal/Plasmid Encoded  -Lactam Hydrolyzing Enzymes  Class A, 2be (TEM-1  TEM-178+, SHV-1  SHV-117+), CTX-M-1  94+), 2f zinc-independent carbapenemases (KPC-1  11), ESBLs, etc.  Many inhibited by clavulanic acid and tazobactam (IRTs)  TEM, SHV, CTX-M: located on plasmids.  First group 2f enzymes were identified on the chromosome and reported in Enterobacter cloacae and Serratia marcescens ( Sme-1,-2, IMI-1, NMC-A)  More recently, KPC  -lactamases were identified and are plasmid associated

10. CLSI Enterobacteriaceae Interpretive Criteria MIC Breakpoints Published by CLSI SAST (  g/mL) Drug Susceptible Intermediate Resistant Cefazolin ≤ 1 (≤ 8)** 2 (16) ≥4 (≥32) Cefotaxime ≤ 1 (≤ 8) 2 (16-32) ≥4 (≥64) Ceftizoxime ≤ 1 (≤ 8) 2 (16-32) ≥4 (≥64) Ceftriaxone ≤ 1 (≤ 8) 2 (16-32) ≥4 (≥64) Ceftazidime ≤ 4 (≤ 8) 8 (16) ≥16 (≥32) Aztreonam ≤ 4 (≤ 8) 8 (16) ≥16 (≥32) Disc Breakpoints Published by CLSI (mm) Drug Susceptible Intermediate Resistant Cefazolin * Not available; unacceptable correlation with MICs Cefotaxime ≥26 23-25 ≤22 Ceftizoxime ≥25 22-24 ≤21 Ceftriaxone ≥23 20-22 ≤19 Ceftazidime ≥21 18-20 ≤17 Aztreonam ≥21 18-20 ≤17 *Problematic for UTI isolates. Consider testing and reporting cephalothin with applicable disclaimer. ** Previous breakpoints are in parentheses

16. EXPOSURE & RESPONSE IN MICE ESBL Versus Non-ESBL Producing Strains Ambrose PG, Bhavnani SM, Jones RN, Craig WA, Dudley MN. Use of PK-PD and Monte Carlo Simulation as Decision Support for the Re-Evaluation of NCCLS Cephem Susceptibility Breakpoints for Enterobacteriaceae [abstract A-138]. 44th ICAAC; Washington; 2004 Oct 30-Nov 2. Washington. Key message: When adequate concentrations of drug are provided, ESBL and non-ESBL producing strains look the same. There is no hidden, “mystery” behind ESBL-producing strains (i.e., “it’s all about the MIC”)

17. Clinical outcome with cephalosporin mono-therapy in 35 patients with bacteremia due to cephalosporin-susceptible, ESBL-producing Klebsiella spp . or E. coli “susceptible” by current breakpoints Craig WA, Bhavnani SM, Ambrose PG, Dudley MN, Jones RN. Evaluation of clinical outcome among patients with ESBL-producing Enterobacteriaceae treated with cephalosporin mono-therapy. ICAAC 2005, Abstract K-1291 CLINICAL DATA in Bacteremia Outcome in Cephalosporin Treatment Correlates with MICs and NOT ESBL Production MIC (mg/L) Cures/Total Percentage ≤ 1 8/11 73 2 6/8 75 4 3/9 33 8 1/7 14

27. Class C, Chromosomally or Plasmid Encoded AMP-C Enzymes  Bush et. al. class 1, (molecular class C) AMP-C type β -lactamases  Chromosomally or plasmid mediated  Hydrolyze oxyiminocephalosporins (ceftriaxone, ceftazidime, cefotaxime, cefpodoxime) and 7-  - methoxy-cephalosporins (cefoxitin, cefotetan, moxalactam).  Also hydrolyze carbapenems at very low rates. They are not significantly inhibited by β -lactamase inhibitors.

34. What gram-negative was recovered from BAL, an empyema collection, urine, and blood?

35. Klebsiella pneumo niae

36. Klebsiella pneumoniae  Polymyxin B MIC = 2  g/mL (Susceptible?)  Patient treated with tigecycline and polymyxin B - responded  Reports in the literature of successful treatment of this organism with polymyxin B plus rifampin and combinations of agents that include imipenem and/or an aminoglycoside

37. The Patient Developed a Second Pneumonia Related to:

38. Follow-up Hyperinfestation with Strongyloides stercoralis

39. Follow-up Treated with ivermectin and recovered, only to develop a new pneumonia with:

42. Follow-up  Aspergillus fumigatus  Again responded to therapy (voriconazole), but developed bilateral CMV pneumonia

43. Follow-up Controlled with high-dose gancyclovir, but became septic with:

45. Multi-drug Resistant Strain of Acinetobacter baumannii   -lactam (including imipenem), aminoglycoside, and fluoroquinolone resistant  Expired 13 months after initial surgery

48. Class B Plasmid-Mediated Metallo-  -Lactamases  IMP-1-first identified and reported in Pseudomonas aeruginosa in 1991 and later in Serratia marcescens  Variants (IMP-2  26) identified predominantly in Pseudomonas aeruginosa , Klebsiella pneumoniae, and Acinetobacter baumannii

51. New CLSI Carbapenem Breakpoints MIC Breakpoints Recently Approved by CLSI SAST (  g/mL) Drug Susceptible Intermediate Resistant Imipenem ≤ 1 (4) 2 (8) ≥4 (16) Meropenem ≤ 1 (4) 2 (8) ≥4 (16) Doripenem ≤ 1 (NA) 2 (NA) ≥4 (NA) Ertapenem ≤ 0.25 (2) 0.5 (4) ≥1 (8) Disc Breakpoints Recently Approved by CLSI SAST (mm) Drug Susceptible Intermediate Resistant Imipenem ≥23 20-22 ≤19 Meropenem ≥23 20-22 ≤19 Doripenem ≥22 20-21 ≤19 Ertapenem ≥23 20-22 ≤19

56. Modified Hodge Test (Carbapenem Inactivation Test) 1 2 3 The MHT performed on a small MHA plate. (1) K. pneumoniae D-05 , positive result; (2) K. pneumoniae 6179, negative result; and (3) a clinical isolate, positive result E. coli ATCC  25922 Inhibition of E. coli ATCC  25922 by ertapenem Enhanced growth of E. coli ATCC  25922. Carbapenemase produced by K. pneumoniae D-05 destroyed ertapenem that diffused into the media. Thus, there is no longer sufficient ertapenem to inhibit E. coli ATCC  25922 and an indentation of the zone is noted.

57. Detection of KPC-mediated Resistance

59. Susceptibility Testing Frequency of Very Major, Major, and Minor Errors Testing Method Number (%) of Isolates with Indicated Result Very Major Major Minor 2010 CLSI Meropenem Interpretive Criteria Etest 1 (2.2) 0 (0) 1 (2.2) Vitek 2 11 (23.9) 0 (0) 18 (39.1) Sensititre 3 (6.5) 0 (0) 12 (26.1) Microscan 0 (0) 0 (0) 1 (2.2) FDA Meropenem Interpretive Criteria__ Etest 1 (2.2) 0 (0) 7 (15.2) Vitek 2 27 (58.7) 0 (0) 8 (17.4) Sensititre 27 (58.7) 0 (0) 12 (26.1) Microscan 0 (0) 0 (0) 2 (4.3) Bulik CC, Fauntleroy KA, Jenkins SG, Abuali M, LaBombardi VJ, Nicolau DP, Kuti JL. 2010. J Clin Microbiol. 48: 2402–2406.

60. imipenem Surgical ICU