From the Guidelines
A CT chest scan with IV contrast is strongly recommended for this patient with ESBL bacteremia who has worsening pneumonia on chest X-ray and increasing oxygen requirements despite meropenem therapy. The patient's clinical deterioration, as evidenced by the need for high-flow nasal cannula oxygen therapy, suggests a potential complication or alternative diagnosis that requires further investigation 1. A CT scan will provide more detailed imaging of the lung parenchyma to identify potential complications such as lung abscess, empyema, or necrotizing pneumonia that may not be visible on plain radiographs.
The use of CT chest with IV contrast is supported by recent guidelines, which recommend it for cases of suspected parapneumonic effusion or empyema 1. The CT findings may guide additional interventions such as drainage procedures, bronchoscopy, or modifications to the antibiotic regimen. While awaiting the CT, ensure adequate respiratory support is maintained and consider obtaining additional blood cultures to assess for persistent bacteremia.
Key considerations for the CT scan include:
- Pleural enhancement, which has the highest area under curve for the diagnosis of empyema 1
- Pleural thickening, loculation, extrapleural fat proliferation, and increased attenuation of the extrapleural fat, which are also commonly associated with empyema 1
- The presence of pleural enhancement with pleural gas/microbubbles or larger pleural effusion size, which can boost the accuracy for identifying parapneumonic effusions requiring thoracentesis 1
Overall, the CT chest scan with IV contrast is a crucial diagnostic tool in this scenario, and its findings will inform further management and potential interventions to improve patient outcomes.
From the Research
Patient Condition and Treatment
- The patient has ESBL (Extended-Spectrum Beta-Lactamase) bacteremia and worsening pneumonia on chest X-ray.
- The patient is currently on meropenem (Meropenem) and has been upgraded from an oxymask to high-flow nasal cannula (HFNC) oxygen therapy.
- Meropenem is a broad-spectrum antibacterial agent effective against Gram-positive and Gram-negative pathogens, including ESBL-producing Enterobacteriaceae 2.
Use of Meropenem in ESBL Infections
- Meropenem is considered a treatment of choice for ESBL-positive gram-negative bacteremia, along with imipenem 3.
- The use of meropenem in patients with suspected healthcare-associated pneumonia and risk factors for MDR/ESBL bacterial infections has been studied, with factors such as admission from a skilled nursing facility/long-term acute care or a history of positive culture for MDR/ESBL pathogens being associated with positive cultures of MDR/ESBL pathogens 4.
Need for CT Chest Scan
- There is no direct evidence in the provided studies to suggest that a CT chest scan is required for a patient with ESBL bacteremia and worsening pneumonia on chest X-ray who has been upgraded to HFNC oxygen therapy.
- The decision to perform a CT chest scan would depend on the patient's clinical condition and the presence of any other symptoms or signs that would warrant further imaging 2, 3, 5, 4, 6.
Clinical Considerations
- The patient's condition, including the presence of septic shock or mechanical ventilation, should be taken into account when deciding on the need for further imaging or adjustments to treatment 5, 6.
- The use of meropenem/vaborbactam for the treatment of infections caused by ESBL-producing Enterobacterales and carbapenem-resistant Klebsiella pneumoniae has shown promise, with clinical success rates of 77% and 30-day mortality rates of 15.4% 6.