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Case of the Month - November 2011

Dr Andrew Whitelaw, Principal Specialist, National Health Laboratory Service

An 86 year old male patient was admitted to an orthopedic ward with a right hip fracture and a right sided pleural effusion. Co-morbidity included diabetes mellitus and hypertension and he was in chronic renal failure on hemodialysis. The patient underwent open reduction and internal fixation of the right hip and had a right sided thoracostomy for the pleural effusion and was subsequently admitted to a high care unit (HCU). Two weeks later the patient was discharged to a renal ward for ongoing hemodialysis. A few days later the patient became delirious with fever and had an increased C-reactive protein and white cell count. Blood cultures and urine cultures taken at the same time revealed no growth. Ten days later whilst on empiric meropenem and linezolid he became hypotensive and obtunded; one day later a urine MC&S grew a Klebsiella pneumoniae that, according to automated susceptibility testing (Vitek 2), was resistant to all commonly used antibiotics (i.e. amino-penicillin’s, β-lactam/β-lactamase inhibitors, aminoglycosides, fluoroquinolones, cephalosporins, tigecycline and carbapenems). Subsequent disc susceptibility testing, showed that fosfomycin and colistin were the only active agents. Based on MIC testing, colistin was the only agent active against this pathogen. The isolate was genotypically analyzed by the Ampath molecular laboratory in Pretoria, to detect the presence of carbapenemase genes and sequencing confirmed the presence of the NDM (blaNDM-1 ) gene. The patient demised however without having received colistin and prior to all the tests being completed.

During his prolonged hospitalization of 40 days the patient received multiple courses of antibiotics which included:

  • Ciprofloxacin
  • Vancomycin
  • Metronidazole (for PCR- confirmed Clostridium difficile diarrhea)
  • Meropenem
  • Linezolid

Question 1: How does carbapenem resistance spread?

Continue to Answer 1