Elevated complement C3 and increased CD8 and type 1 helper lymphocyte T populations in patients with post-COVID-19 condition.

BACKGROUND: Biological markers associated to post-COVID-19 condition (PCC) have not been clearly identified. METHODS: Eighty-two patients attending our post-COVID-19 outpatient clinic were recruited and classified as fully recovered (40.2%) or presenting with PCC (59.8%). Clinical and radiological data, laboratory markers, cytokines, and lymphocyte populations were analyzed. RESULTS: Median number of days after hospitalization was 78.5 [p25-p75: 60-93] days. PCC was significantly more frequent in women, in patients with a previously critical COVID-19, and in those with two or more comorbidities. No differences were found in lymphocyte counts, ferritin, C-reactive protein, D-dimer or sCD25, IL-1ß, IL-1Ra, IL-6, CXCL8, IL-17A, IL-18, IL-22, IFN-γ, TNF-α, and IL-10 cytokines levels. PCC patients showed significantly higher levels of complement factor C3 than fully recovered patients: median C3 128 mg/dL [p25-p75:107-135] vs 111 mg/dL [p25-p75: 100-125] (p =.005), respectively. In the flow cytometry assessment of peripheral blood lymphocyte subpopulations, PCC patients showed significantly increased CD8 populations compared to fully recovered patients: median CD8: 529 [p25-p75: 384-683] vs 370/mm3 [p25-p75:280-523], p =.007. When type 1, 2, 17/22, and 17.1 helper and follicular T lymphocyte subpopulations were analyzed, the frequency of Th1 was significantly higher in PCC patients compared to fully recovered patients (30% vs 38.5%, p =.028). CONCLUSION: Patients with a post-COVID-19 condition showed significantly increased immunological parameters of inflammation (complement factor C3 and CD8 and Th1 T lymphocyte populations) compared to fully recovered patients. These parameters could be used as biological markers of this condition.

Higher MICs (>2 mg/L) Predict 30-Day Mortality in Patients With Lower Respiratory Tract Infections Caused by Multidrug- and Extensively Drug-Resistant Pseudomonas aeruginosa Treated With Ceftolozane/Tazobactam.

BACKGROUND: Ceftolozane/tazobactam (C/T) efficacy and safety in ventilator-associated pneumonia (VAP) is being evaluated at a double dose by several trials. This dosing is based on a pharmacokinetic (PK) model that demonstrated that 3 g q8h achieved ≥90% probability of target attainment (50% ƒT > minimal inhibitory concentration [MIC]) in plasma and epithelial lining fluid against C/T-susceptible P. aeruginosa. The aim of this study was to evaluate the efficacy of different C/T doses in patients with lower respiratory infection (LRI) due to MDR- or XDR-P. aeruginosa considering the C/T MIC. METHODS: This was a multicenter retrospective study of 90 patients with LRI caused by resistant P. aeruginosa who received a standard or high dose (HDo) of C/T. Univariable and multivariable analyses were performed to identify independent predictors of 30-day mortality. RESULTS: The median age (interquartile range) was 65 (51-74) years. Sixty-three (70%) patients had pneumonia, and 27 (30%) had tracheobronchitis. Thirty-three (36.7%) were ventilator-associated respiratory infections. The median C/T MIC (range) was 2 (0.5-4) mg/L. Fifty-four (60%) patients received HDo. Thirty-day mortality was 27.8% (25/90). Mortality was significantly lower in patients with P. aeruginosa strains with MIC ≤2 mg/L and receiving HDo compared with the groups with the same or higher MIC and dosage (16.2% vs 35.8%; P = .041). Multivariate analysis identified septic shock (P < .001), C/T MIC >2 mg/L (P = .045), and increasing Charlson Comorbidity Index (P = .019) as independent predictors of mortality. CONCLUSIONS: The effectiveness of C/T in P. aeruginosa LRI was associated with an MIC ≤2 mg/L, and the lowest mortality was observed when HDo was administered for strains with C/T MIC ≤2 mg/L. HDo was not statistically associated with a better outcome.

Ceftolozane/tazobactam for the treatment of multidrug resistant Pseudomonas aeruginosa: experience from the Balearic Islands.

A prospective, descriptive observational study of consecutive patients treated with ceftolozane/tazobactam in the reference hospital of the Balearic Islands (Spain), between May 2016 and September 2017, was performed. Demographic, clinical, and microbiological variables were recorded. The later included resistance profile, molecular typing, and whole genome sequencing of isolates showing resistance development. Fifty-eight patients were treated with ceftolozane/tazobactam. Thirty-five (60.3%) showed respiratory tract infections, 21 (36.2%) received monotherapy, and 37 (63.8%) combined therapy for ≥ 72 h, mainly with colistin (45.9%). In 46.6% of the patients, a dose of 1/0.5 g/8 h was used, whereas 2/1 g/8 h was used in 41.4%. In 56 of the cases (96.6%), the initial Pseudomonas aeruginosa isolates recovered showed a multidrug resistant (MDR) phenotype, and 50 of them (86.2%) additionally met the extensively drug resistant (XDR) criteria and were only susceptible colistin and/or aminoglycosides (mostly amikacin). The epidemic high-risk clone ST175 was detected in 50% of the patients. Clinical cure was documented in 37 patients (63.8%) and resistance development in 8 (13.8%). Clinical failure was associated with disease severity (SOFA), ventilator-dependent respiratory failure, XDR profile, high-risk clone ST175, negative control culture, and resistance development. In 6 of the 8 cases, resistance development was caused by structural mutations in AmpC, including some mutations described for the first time in vivo, whereas in the other 2, by mutations in OXA-10 leading to the extended spectrum OXA-14. Although further clinical experience is still needed, our results suggest that ceftolozane/tazobactam is an attractive option for the treatment of MDR/XDR P. aeruginosa infections.

Mechanisms leading to in vivo ceftolozane/tazobactam resistance development during the treatment of infections caused by MDR Pseudomonas aeruginosa.

Objectives: Characterization of the mechanisms driving ceftolozane/tazobactam resistance development in 5 of 47 (10.6%) patients treated for MDR Pseudomonas aeruginosa infections in a Spanish hospital. Methods: Five pairs of ceftolozane/tazobactam-susceptible/resistant P. aeruginosa isolates were studied. MICs were determined by broth microdilution, clonal relatedness was assessed by MLST and resistance mechanisms were investigated by phenotypic and genotypic methods, including WGS. ampC variants were cloned to assess their impact on resistance. Results: In all five cases, the same clone was detected for the susceptible/resistant pairs; the widespread ST175 high-risk clone in four of the cases and ST179 in the remaining case. Genomic analysis of the four initial ST175 isolates revealed the characteristic OprD mutation (Q142X) responsible for carbapenem resistance and the AmpR mutation (G154R) responsible for AmpC overexpression and ß-lactam resistance. The final isolates had developed ceftolozane/tazobactam and ceftazidime/avibactam resistance, and each additionally showed a mutation in AmpC: E247K in one of the isolates, T96I in two isolates and a deletion of 19 amino acids (G229-E247) in the remaining isolate. The cloned AmpC variants showed greatly increased ceftolozane/tazobactam and ceftazidime/avibactam MICs compared with WT AmpC, but, in contrast, yielded lower MICs of imipenem, cefepime and particularly piperacillin/tazobactam. On the other hand, ceftolozane/tazobactam resistance development in ST179 was shown to be driven by the emergence of the extended-spectrum OXA ß-lactamase OXA-14, through the selection of an N146S mutation from OXA-10. Conclusions: Modification of intrinsic (AmpC) and horizontally acquired ß-lactamases appears to be the main mechanism leading to ceftolozane/tazobactam resistance in MDR P. aeruginosa.