Performance and impact of rapid multiplex PCR on diagnosis and treatment of ventilated hospital-acquired pneumonia in patients with extended-spectrum ß-lactamase-producing Enterobacterales rectal carriage.

BACKGROUND: Antimicrobial stewardship (AMS) for ventilator-associated pneumonia (VAP) or ventilated hospital-acquired pneumonia (vHAP) in extended-spectrum ß-lactamase-producing Enterobacterales (ESBL-E) carriers is challenging. BioFire® FilmArray® Pneumonia plus Panel (mPCR) can detect bacteria and antibiotic resistance genes, including blaCTX-M, the most common ESBL-encoding gene. METHODS: This monocentric, prospective study was conducted on a group of ESBL-E carriers from March 2020 to August 2022. The primary objective was to evaluate the concordance between the results of mPCR and conventional culture performed on respiratory samples of ESBL-E carriers to investigate suspected VAP/vHAP. The secondary objective was to appraise the impact of performing or not mPCR on initial antibiotic therapy adequacy in ESBL-E carriers with confirmed VAP/vHAP. RESULTS: Over the study period, 294 patients with ESBL-E carriage were admitted to the ICU, of who 168 (57%) were mechanically ventilated. (i) Diagnostic performance of mPCR was evaluated in suspected 41 episodes of VAP/vHAP: blaCTX-M gene was detected in 15/41 (37%) episodes, where 9/15 (60%) were confirmed ESBL-E-induced pneumonia. The culture and blaCTX-M were concordant in 35/41 (85%) episodes, and in all episodes where blaCTX-M was negative (n = 26), the culture never detected ESBL-E. (ii) The impact of mPCR on initial antibiotic therapy adequacy was assessed in 95 episodes of confirmed VAP/vHAP (22 episodes were tested with mPCR and 73 without); 47 (49%) episodes were ESBL-E-induced, and 24 (25%) were carbapenem-resistant bacteria-induced. The use of mPCR was significantly associated with higher prescription of adequate empirical antibiotic therapy in the multivariable logistic regression (adjusted odds ratio (aOR) (95% CI) of 7.5 (2.1-35.9), p = 0.004), propensity-weighting (aOR of 5.9 (1.6-22.1), p = 0.008), and matching-cohort models (aOR of 5.8 (1.5-22.1), p = 0.01). CONCLUSION: mPCR blaCTX-M showed an excellent diagnostic value to rule out the diagnosis of ESBL-E related pneumonia in ESBL-E carriers with suspected VAP/vHAP. In addition, in patients with confirmed VAP/vHAP, a mPCR-based antibiotic therapy was associated with an increased prescription of adequate empirical antibiotic therapy. Performing mPCR on respiratory samples seems to be a promising tool in ESBL-E carriers with suspected vHAP/VAP. However, if mPCR is used in very low pre-test clinical probability of pneumonia, due to the high sensitivity and the rate of overdiagnosed pneumonia, the risk of overconsumption of carbapenem may prevail. Further studies are warranted.

Chest Computed Tomography Characteristics of Critically Ill COVID-19 Patients with Auto-antibodies Against Type I Interferons.

PURPOSE: Patients with auto-antibodies neutralizing type I interferons (anti-IFN auto-Abs) are at risk of severe forms of coronavirus disease 19 (COVID-19). The chest computed tomography (CT) scan characteristics of critically ill COVID-19 patients harboring these auto-Abs have never been reported. METHODS: Bicentric ancillary study of the ANTICOV study (observational prospective cohort of severe COVID-19 patients admitted to the intensive care unit (ICU) for hypoxemic acute respiratory failure between March 2020 and May 2021) on chest CT scan characteristics (severity score, parenchymal, pleural, vascular patterns). Anti-IFN auto-Abs were detected using a luciferase neutralization reporting assay. Imaging data were collected through independent blinded reading of two thoracic radiologists of chest CT studies performed at ICU admission (± 72 h). The primary outcome measure was the evaluation of severity by the total severity score (TSS) and the CT severity score (CTSS) according to the presence or absence of anti-IFN auto-Abs. RESULTS: Two hundred thirty-one critically ill COVID-19 patients were included in the study (mean age 59.5 ± 12.7 years; males 74.6%). Day 90 mortality was 29.5% (n = 72/244). There was a trend towards more severe radiological lesions in patients with anti-IFN auto-Abs than in others, not reaching statistical significance (median CTSS 27.5 (21.0-34.8) versus 24.0 (19.0-30.0), p = 0.052; median TSS 14.5 (10.2-17.0) versus 12.0 (9.0-15.0), p = 0.070). The extra-parenchymal evaluation found no difference in the proportion of patients with pleural effusion, mediastinal lymphadenopathy, or thymal abnormalities in the two populations. The prevalence of pulmonary embolism was not significantly different between groups (8.7% versus 5.3%, p = 0.623, n = 175). CONCLUSION: There was no significant difference in disease severity as evaluated by chest CT in severe COVID-19 patients admitted to the ICU for hypoxemic acute respiratory failure with or without anti-IFN auto-Abs.