Outcome of febrile neutropenic patients treated for bacteriuria in hematology

INTRODUCTION

Positive urine sample is a frequent finding in post-chemotherapy febrile neutropenia (FN) and can lead to prolonged antibiotic therapy. The aim of this study was to assess the outcome of bacteriuria episodes in FN patients receiving targeted antibiotic therapy.

MATERIALS AND METHODS

A multi-centric retrospective study was conducted over a four-year period (2014-2019) on systematic urinalysis. All consecutive first bacteriuria episodes (≤ 2 bacteria with at least ≥ 10³ CFU/mL) during FN in hospitalized adult patients for hematological malignancies were included. Relapse and recurrence were defined by fever or urinary tract symptoms (UTS) with the same bacterial subspecies in urine occurring ≤ 7 days and ≤ 30 days, respectively, after antibiotic discontinuation. Mortality rate was determined at 30 days. Targeted antibiotic therapy ≤ 10 days for women and ≤ 14 for men was considered as short course.

RESULTS

Among 97 patients, 105 bacteriuria episodes on systematic urinalysis were analyzed; 67.6% occurred in women, 41.9% in AML patients, 17.1% were bacteremic, 14.2% presented with UTS, and 61.9% were treated with short-course antibiotic treatment. One death was reported. In men, no relapse/recurrence was noted, even in the short-course antibiotic group. In women, 2.8% of episodes treated with short-course antibiotic led to relapse or recurrence.

CONCLUSIONS

Relapse, recurrence, and mortality were uncommon events in FN patients experiencing bacteriuria episode, whatever the antibiotic duration. To distinguish asymptomatic bacteriuria from infection remained challenging in women. In men, systematic urinalysis at onset of FN could be useful.

Why Methodology Is Important: Coffee as a Candidate Treatment for COVID-19?

BACKGROUND

During this pandemic situation, some studies have led to hasty conclusions about Corona Virus Disease-19 (COVID-19) treatment, due to a lack of methodology. This pedagogic study aimed to highlight potential biases in research on COVID-19 treatment.

METHODS

We evaluate the effect of coffee's active part, 1,3,7-trimethylxanthine (TMX) on patients with COVID-19. A cohort of 93 patients, with a diagnosis of COVID-19 is analyzed.

RESULTS

TMX group and control group included, respectively, 26 and 67 patients. In the TMX group, patients had a median length of stay in hospital of 5.5 days shorter than in the control group (9.5 vs. 15 days, p < 0.05). Patients in the control group were more severe than patients in the TMX group with a significantly higher National Early Warning Score 2 (NEWS-2 score) (8 vs. 6, p = 0.002).

CONCLUSIONS

Multiple biases prevents us from concluding to an effect of coffee on COVID-19. Despite an important social pressure during this crisis, methodology and conscientiousness are the best way to avoid hasty conclusions that can be deleterious for patients. Identifier: NCT04395742.

2202. Validation of a Rabbit Model of Pseudomonas aeruginosa Acute Pneumonia

Background

Severity and antimicrobial resistance of P. aeruginosa (PA) hospital-acquired pneumonia led the FDA to encourage the development of animal models for preclinical evaluation of new therapeutic strategies. We present here the validation of a rabbit model of PA acute pneumonia.

Methods

Rabbits were infected by endotracheal instillation of 1.8 mL of a standardized inoculum containing 9 × 10⁷ CFU of PA clinical strain 6206 (predetermined 100% lethal dose). The natural history of the disease was described by the following parameters evaluated at 3, 4, 5, 6, 10 hours post-infection (hpi) and at the time of spontaneous death (6 rabbits/group): lung-to-body weight ratio (LW/BW), pulmonary, splenic and renal bacterial counts, pulmonary histology and blood markers (blood cell counts, blood gas and IL-8). Three groups of 12 rabbits were then treated with saline (controls), tobramycin or meropenem at doses determined by PK/PD analysis to confirm the efficacy of a human-equivalent dosing regimen.

Results

PA strain 6,206 caused fatal pneumonia in 13–23 hours by acute respiratory distress syndrome (pulmonary edema and necrosis with LW/BW > 10, pO₂ <40 mmHg) and/or sepsis (hyperlactatemia, hypoglycemia, cytopenias). LW/BW and pulmonary bacterial counts increased significantly over time. The splenic and renal bacterial spread was constant after 6 hpi. Hypoxemia <60 mmHg appeared at 5 hpi for 4/6 rabbits, associated with elevated plasma IL-8 concentration, massive neutrophilic influx into the airspace, lung necrosis, hemorrhage, and pulmonary edema formation. Consequently, 5 hpi appeared as the most appropriate time to trigger a therapeutic intervention. Meropenem (80 mg/kg/q2h) or tobramycin (1 injection of 2.5 mg/kg, then saline/q2h) showed superiority over saline, with a mortality rate of 33% and 17% vs. 100%, and an LW/BW ratio of 8.53 and 8.54 vs. 13.9, respectively. Tobramycin was less effective than meropenem in clearing bacteria, with, respectively, 1 and 9 out of 12 rabbits having sterile samples.

Conclusion

This rabbit model of PA acute pneumonia is a reliable evaluation tool for new therapeutic strategies. Our study also provides guidance for the development of animal models by describing the natural history of disease and therapeutic validation.

Disclosures

All authors: No reported disclosures.

713. Preventive Administration of MEDI6389, a Combination of Monoclonal Antibodies (mAbs) Targeting Alpha-Toxin (AT), Panton-Valentine Leukocidin (PVL), Leukocidin ED (LukED), Gamma-Hemolysin and Clumping Factor A (ClfA), in a Rabbit Model of USA300 MRSA Prosthetic Joint Infection (PJI)

Background

mAbs targeting staphylococcal virulence factors could represent an interesting preventive strategy in PJI. We evaluate here MEDI6389 compared with isotype-matched control IgG (c-IgG) in a rabbit model of USA300 MRSA PJI.

Methods

Rabbits were randomized for prophylaxis with either c-IgG (n = 13; 30 mg/kg; controls) or MEDI6389 (n = 13; 30 mg/kg of each mAb) administered intravenously 12h before infection. A cemented screw and ultrahigh-molecular-weight polyethylene washer were placed intraarticularly in the external femoral condyle. After suturing the joint capsule and musculocutaneous layers, 300 µL of a standardized bacterial inoculum containing 5 × 10⁵ CFU of a USA300 MRSA clinical isolate were injected intraarticularly. Animals were euthanized on day 8 and the knee joint was harvested for bacteriological analysis (synovial bacterial counts, and enumeration of screw-adherent bacteria after sonication) and histology (conventional pathology, and transmission electron microscopy [TEM] for neutrophils analysis). In vivo observations made on neutrophils were confirmed by TEM analysis of human neutrophils incubated in vitro with purified PVL, LukED, and gamma-hemolysin with or without the corresponding mAb.

Results

In comparison with the control group, the average amount of pus (1.7 ± 1.8 vs. 3.1 ± 1.2 g, P = 0.026) and the number of bacteria in the synovial pus (5.9±1.5 vs. 7.2±1.4 log10 CFU, P = 0.031) and on the screw (2.7 ± 1.5 vs. 4.1 ± 1.6 log10 CFU, P = 0.035) were decreased in animals pretreated by MEDI6389. Conventional pathological examination showed a marked reduction in synovitis of MEDI6389-pretreated animals. TEM of synovitis harvested from infected knee joints of control animals showed significant greater number of abnormal neutrophils that appeared rounded, with condensed nucleus and no granules, compared with those pretreated with MEDI6389 (P = 0.002). This classical leukocidin-induced neutrophilic killing phenotype could be neutralized with anti-leukocidin mAbs using ex vivo human neutrophils incubated with PVL, LukED, HlgAB, or HlgCB.

Conclusion

The preventive administration of MEDI6389 allows a reduction of local inflammation and bacterial burden in this USA300 MRSA rabbit PJI model.

Disclosures

All authors: No reported disclosures.

Combined measurement of carbon monoxide and nitric oxide lung transfer does not improve the identification of pulmonary hypertension in systemic sclerosis

Screening is important to determine whether patients with systemic sclerosis (SSc) have pulmonary hypertension because earlier pulmonary hypertension treatment can improve survival in these patients. Although decreased transfer factor of the lung for carbon monoxide (TLCO) is currently considered the best pulmonary function test for screening for pulmonary hypertension in SSc, small series have suggested that partitioning TLCO into membrane conductance (diffusing capacity) for carbon monoxide (DMCO) and alveolar capillary blood volume (VC) through combined measurement of TLCO and transfer factor of the lung for nitric oxide (TLNO) is more effective to identify pulmonary hypertension in SSc patients compared with TLCO alone. Here, the objective was to determine whether combined TLCO–TLNO partitioned with recently refined equations could more accurately detect pulmonary hypertension than TLCO alone in SSc.

For that purpose, 572 unselected consecutive SSc patients were retrospectively recruited in seven French centres.

Pulmonary hypertension was diagnosed with right heart catheterisation in 58 patients. TLCO, TLNO and VC were all lower in SSc patients with pulmonary hypertension than in SSc patients without pulmonary hypertension. The area under the receiver operating characteristic curve for the presence of pulmonary hypertension was equivalent for TLCO (0.82, 95% CI 0.79–0.85) and TLNO (0.80, 95% CI 0.76–0.83), but lower for VC (0.75, 95% CI 0.71–0.78) and DMCO (0.66, 95% CI 0.62–0.70).

Compared with TLCO alone, combined TLCO–TLNO does not add capability to detect pulmonary hypertension in unselected SSc patients.