Arsanis Study Finds Antibiotics Ineffective Against Staphylococcus aureus Pneumonia

Arsanis Study Finds Antibiotics Ineffective Against Staphylococcus aureus Pneumonia

Arsanis recently presented prospective epidemiological findings showing that antibiotics to fight infections caused by Staphylococcus aureus bacteria did not significantly prevent or reduce their colonization, and did not halt progression to pneumonia.

Those are the results of a study that assessed the progression of Staphylococcus aureus airway colonization to pneumonia, and the impact of antibiotics in mechanically ventilated patients. The findings were shown at IDWeek 2016 in New Orleans, in a presentation titled “Staphylococcus aureus colonized patients receiving mechanical ventilation progress to pneumonia despite antibiotic treatment“.

“Arsanis is driven by a sense of urgency to advance novel approaches for the prevention and treatment of serious infections,” Rene Russo, chief executive officer of Arsanis, said in a press release. “This study shines a bright light on the unmet need in S. aureus pneumonia in high-risk, mechanically ventilated patients, and has informed the design of our Phase 2 trial of ASN100,” she said.

ASN100 is a monoclonal antibody in development for the treatment of S. aureus infection that targets multiple virulence factors simultaneously, an approach the company believes necessary to have a robust treatment response. ASN100 will be evaluated soon in a Phase 2 clinical trial (NCT02940626), that is not yet recruiting participants.

S. aureus is the most common species of staphylococcus bacteria causing infections in humans. Colonization of the airways by these bacteria is a risk factor for ventilator-associated pneumonia (VAP), a type of lung infection that occurs in people who are on breathing machines in hospitals. The infection typically affects critically ill persons who are in intensive care units.

The prospective, observational cohort study followed the progression of upper and lower airway S. aureus colonization to VAP, and examined the impact of S. aureus-active antibiotics in 238 patients who had been mechanically ventilated for more than 48 hours.

Researchers found that 37 patients had heavy tracheal S. aureus colonization. Of these patients, 29.7% (11 patients) developed S. aureus pneumonia while on mechanical ventilation (VAP). This rate of VAP diagnosis was found despite the fact that 90.9% of these patients were administered with S. aureus active antibiotics.

Results of this study support previous results in which the researchers found that of 231 mechanically ventilated patients, 21.2% (49 patients) had heavy tracheal S. aureus colonization, and 38.5% of these patients (15 patients) progressed to S. aureus pneumonia despite having received antibiotic treatment.

“The progression to S. aureus pneumonia observed in approximately one-third of heavily colonized patients, despite the vast majority receiving relevant antibiotic treatment, highlights the unmet need for novel preventative and therapeutic approaches for these critically ill patients,” said Chris Stevens, MD, executive vice president and chief medical officer of Arsanis. “We look forward to beginning our Phase 2 study of ASN100 in heavily colonized, mechanically ventilated patients and expect to dose the first patient in this study in coming weeks.”

“The practice of administering antibiotics to patients presenting with positive respiratory cultures is common, yet not supported by current guidelines,” added Eszter Nagy, MD, PhD, co-founder and chief scientific officer of Arsanis. “Considering the virulence-enhancing effect of antibiotics on S. aureus due to increased toxin production, and the potentially negative impact on the microbiome and resistance development, these data support antibiotic-sparing strategies and antimicrobial stewardship,” said Nagy.

Arsanis is planning to publish the full results of its study, including data from additional patients, in a peer-reviewed medical journal.

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