A 76 year old man finally improved after a prolonged and complicated course in the ICU and was transferred to an intermediate care unit.  Two days later he developed pneumonia and became septic.  Empiric therapy with piperacillin/tazobactam was initiated but without improvement.  Sputum and blood cultures yielded Klebsiella pneumoniae.  The following is a portion of his antibiotic susceptibility results:

            Piperacillin/tazobactam          Resistant

            Ceftriaxone                             Resistant

            Ceftazidime                             Susceptible

            Cefepime                                 Susceptible

            Ertapenem                              Resistant

            Imipenem                                Resistant

            Meropenem                            Resistant

Which of the following carbapenemases is most likely to produce this pattern?

A.      KPC – Class A serine carbapenemase

B.      NDM-1 – A Class B metallo-beta lactamase

C.      AmpC – A Class C serine carbapenemase

D.     OXA-48-like – A Class D serine carbapenemase

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A 65 year old man returns from a visit to family in India where he, unfortunately, had been hospitalized because of injuries suffered in a motor vehicle accident.  Shortly after arriving in the U.S. he was admitted to hospital with sepsis and failed to improve while receiving empiric therapy with ertapenem.  Cultures of blood and urine each yielded Escherichia coli.  The following is a portion of his antibiotic susceptibility results:

            Piperacillin/tazobactam          Resistant

            Ceftriaxone                             Resistant

            Ceftazidime                             Resistant

            Cefepime                                 Resistant

            Ertapenem                              Resistant

            Imipenem                                Resistant

            Meropenem                            Resistant

Further testing demonstrates the presence of an NDM metallo-carbapenemase.  Which of the following is a reasonable choice of empiric antibiotic therapy while awaiting further phenotypic susceptibility testing?  More than one answer may be correct.

A.      Ceftazidime/avibactam

B.      Meropenem/vaborbactam

C.      Ceftazidime/avibactam + aztreonam

D.     Cefiderocol

E.      Ceftolozane/tazobactam 

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