Carbapenem-Resistant Organism on a Surgical Unit
A 52-year-old woman is on postoperative day 6 after an open abdominal procedure. She has a temporary ileostomy, a midline wound, and a central line. Surveillance rectal culture on admission was negative for carbapenemase-producing organisms (CPO). On day 5 she develops fever, hypotension, and increasing abdominal pain. Blood cultures grow a carbapenem-resistant Klebsiella pneumoniae (meropenem MIC 16 mg/L). The laboratory confirms carbapenemase production by a phenotypic test and reports it as a carbapenemase-producing organism. She is in a semi-private room; her roommate is a 74-year-old man recovering from a hip fracture. The unit has two isolation-capable rooms, both currently occupied by patients with contact precautions for other reasons. Infection prevention is called.
1. Outline the immediate infection prevention actions and justify the priority order.
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Immediate actions, in priority order: (1) Place the patient in contact precautions now, ideally a single room; if none is available, cohort with another CPO patient rather than with a susceptible roommate, and move the hip-fracture patient out of the shared room first. (2) Perform hand hygiene with soap and water or an alcohol-based rub per policy; for CPO, alcohol rub is acceptable, but soap and water is preferred when caring for patients with C. difficile-not the issue here-so alcohol rub is fine. (3) Use gown and gloves for all room entry. (4) Dedicate equipment (stethoscope, thermometer, blood pressure cuff) to the room. (5) Notify receiving departments (OR, imaging) before transport. (6) Notify the clinical team and pharmacy for antimicrobial stewardship review. Justification: CPO spreads by contact, and the roommate is the highest-risk exposed patient; separating them and cohorting the CPO patient limits transmission. Single room is preferred but not always possible; cohorting with another CPO patient is the accepted fallback.
2. The laboratory asks whether to screen the roommate and other unit patients. What is your recommendation?
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Screen the roommate and any patient who shared equipment or a bathroom with the index patient, and consider broader point-prevalence screening on the unit if transmission is suspected. Screening should use a rectal or perirectal swab (or stool) cultured on selective media with carbapenem disks, or a molecular carbapenemase assay if available. The roommate should be screened because of direct exposure; other unit patients should be screened if there is evidence of shared equipment or staff cohorting lapses. Screening results guide cohorting and room assignment. Because the index patient was negative on admission surveillance, the new positivity suggests acquisition during this stay, which raises the possibility of an environmental or staff-mediated source; a targeted environmental culture of shared equipment may be warranted if a second case appears.
3. The patient's blood isolate is reported as carbapenemase-producing. What does this mean for therapy, and what should the laboratory communicate?
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Carbapenemase production means the organism can hydrolyze carbapenems and often other beta-lactams, so standard beta-lactam therapy is unreliable. The laboratory should report the specific carbapenemase type if determined (e.g., KPC, NDM, OXA-48), because it predicts which newer agents are active: KPC is generally susceptible to ceftazidime-avibactam and meropenem-vaborbactam, while metallo-beta-lactamases such as NDM are not inhibited by avibactam and may require aztreonam-avibactam or cefiderocol. The laboratory should ensure susceptibility testing includes these agents or refer to a reference laboratory. Communication should state the resistance mechanism, not just the MIC, and should flag that the result is not a routine carbapenem-resistant Enterobacterales isolate. The care team should involve infectious disease and pharmacy promptly.