Top Infectious Disease News Stories Week of July 5- July 11

Susceptible…but Not Responding: When Lab Results Don’t Match the Patient

A patient with Staphylococcus aureus bacteremia is found to have infective endocarditis. Susceptibility testing results demonstrate a methicillin-susceptible isolate, and appropriate therapy is initiated with first-generation cephalosporin. Despite this, results from repeat blood cultures remain persistently positive over several days. The antibiotic selection appears appropriate based on laboratory data, yet the infection is not clearing as expected.

Most clinicians have encountered a similar clinical scenario. Susceptibility results are often treated as definitive, but they are generated under standardized laboratory conditions that do not fully reflect what is happening in the patient. Understanding where those results can mislead us is especially important in bacteremia, where small missteps can have meaningful consequences.

At its core, susceptibility testing is about standardization. The minimum inhibitory concentration (MIC) represents the lowest concentration of an antibiotic that inhibits visible bacterial growth under controlled conditions. Those conditions include a standardized bacterial inoculum, stable drug exposure, and an optimized environment. That consistency is necessary but may not reflect what is happening in a real-life patient. A patient with Staphylococcus aureus bacteremia is found to have infective endocarditis. Susceptibility testing results demonstrate a methicillin-susceptible isolate, and appropriate therapy is initiated with first-generation cephalosporin. Despite this, results from repeat blood cultures remain persistently positive over several days. The antibiotic selection appears appropriate based on laboratory data, yet the infection is not clearing as expected.

During Current Outbreak, bioMérieux Delivers its Ebola Rapid Diagnostics Testing in Central Africa

As public health officials work to contain the ongoing Bundibugyo Ebola outbreak in Central Africa, rapid and highly accurate diagnostics are critical to identifying cases, guiding patient care, and supporting outbreak control measures.

During a recent Contagion podcast, Chuck Cooper, MD, chief medical officer at bioMérieux, discussed the unique challenges posed by different Ebola virus species and how the company's molecular diagnostic platform is helping frontline healthcare workers respond more effectively.

Important Clinical Practice Takeaways From the DOTs and PETERPEN Trials

According to Megan Klatt, PharmD, BCIDP, DPLA, infectious diseases and antimicrobial stewardship clinical pharmacist at the University of Kansas Health System, 2 studies from the past year stand out for antimicrobial stewardship teams. The DOTS trial (NCT04775953) evaluated dalbavancin (Dalvance; AbbVie) as an alternative to prolonged intravenous therapy for complicated Staphylococcus aureus bacteremia.¹

Complicated S aureus bacteremia typically requires 4 to 6 weeks of intravenous antibiotic therapy, carrying risks of catheter complications and added nursing and laboratory costs. Carbapenem-sparing options for extended-spectrum β-lactamase (ESβL)–producing Enterobacterales remain a stewardship priority as carbapenem use drives further resistance. Both questions have persisted since findings from the original MERINO trial linked piperacillin-tazobactam to a mortality disadvantage against meropenem in 2018.²

FDA Grants Priority Review for Dolutegravir in Newborns With HIV

According to a new announcement from ViiV Healthcare, the FDA has accepted a supplemental New Drug Application (sNDA) for dolutegravir (Tivicay PD, ViiV Healthcare) to extend its use to newborns from birth, granting Priority Review with a PDUFA action date of August 25, 2026.¹ The European Medicines Agency (EMA) simultaneously validated a separate marketing application for dolutegravir (Tivicay, ViiV Healthcare) in the same neonatal population.¹

The regulatory milestones mark a significant step in closing one of the most persistent gaps in HIV treatment: access to modern antiretroviral therapy for the youngest patients. Dolutegravir is a second-generation integrase strand transfer inhibitor (INSTI) with a higher barrier to resistance than previous-generation agents; if approved, it would be the first second-generation INSTI available for newborns.

SNAP Trial Findings Favor Penicillin Over Antistaphylococcal Penicillins for Susceptible Staph Bacteremia

Benzylpenicillin is as effective as, and safer than, the antistaphylococcal penicillins cloxacillin or flucloxacillin in treating penicillin-susceptible Staphylococcus aureus (PSSA), according to findings of the global Staphylococcus aureus Network Adaptive Platform (SNAP) trial.¹

Although the rise of penicillinase-producing S aureus prompted development and widespread use of the antistaphylococcal semisynthetic penicillins, the investigators point out that PSSA is reemerging internationally—responsible for up to 25% of all clinical S aureus isolates in some areas—and that treatment with penicillin has fewer associated adverse effects such as phlebitis, hepatotoxicity, and nephrotoxicity.