Antimicrobial susceptibility testing of bone and joint pathogens using isothermal microcalorimetry.

The rise in osteomyelitis and periprosthetic joint infections, in combination with increasing life expectancy and the prevalence of diabetes, underscores the urgent need for rapid and accurate diagnostic tools. Conventional culture-based methods are often time-consuming and prone to false-negatives, leading to prolonged and inappropriate antibiotic treatments. This study aims to improve osteomyelitis diagnostics by decreasing the time to detection and the time to an antibiotic susceptibility result to enable a targeted treatment using isothermal microcalorimetry (IMC). IMC measures heat flow in real-time, providing insights into bacterial metabolism without the need for labeling. Using clinical isolates from bone infections, assessing their response to antibiotics through IMC, we demonstrated that IMC could detect bacteria within 4 h and determine antimicrobial susceptibility profiles within 2-22 h (median 4.85, range 1.28-21.78). This is significantly faster than traditional methods. A decision tree, based on antibiotic susceptibility, accurately categorized pathogens, achieving high accuracy (74-100%), sensitivity (100%), and specificity (65-100%). These findings suggest that IMC could redefine diagnostics of bone and joint infections and potentially infections in general, offering timely and precise treatment guidance, thereby improving patient outcomes and reducing health care burdens. Further optimization and clinical validation are needed to fully integrate IMC into routine diagnostics.

Hit-to-Lead Identification and Validation of a Triaromatic Pleuromutilin Antibiotic Candidate.

Herein, we report the hit-to-lead identification of a drug-like pleuromutilin conjugate 16, based on a triaromatic hit reported in 2020. The lead arose as the clear candidate from a hit-optimization campaign in which Gram-positive antibacterial activity, solubility, and P-gp affinity were optimized. Conjugate 16 was extensively evaluated for its in vitro ADMET performance which, apart from solubility, was overall on par with lefamulin. This evaluation included Caco-2 cell permeability, plasma protein binding, hERG inhibition, cytotoxicity, metabolism in microsomes and CYP3A4, resistance induction, and time-kill kinetics. Intravenous pharmacokinetics of 16 proved satisfactory in both mice and pigs; however, oral bioavailability was limited likely due to insufficient solubility. The in vivo efficacy was evaluated in mice, systemically infected with Staphylococcus aureus, where 16 showed rapid reduction in blood bacteriaemia. Through our comprehensive studies, lead 16 has emerged as a highly promising and safe antibiotic candidate for the treatment of Gram-positive bacterial infections.

Persistence and genetic adaptation of Pseudomonas aeruginosa in patients with chronic obstructive pulmonary disease.

OBJECTIVES: It is unclear whether recurrent sputum culture with Pseudomonas aeruginosa from patients with chronic obstructive pulmonary disease (COPD) is caused by intermittent airway carriage by different P. aeruginosa lineages or persistent carriage by the same lineage, and whether lineages genetically adapt during carriage. METHODS: Whole-genome sequencing was performed for P. aeruginosa isolates sampled longitudinally from sputum cultures in patients with COPD who were enrolled in an ongoing randomized controlled trial (clinicaltrials.gov: NCT03262142). RESULTS: A total of 153 P. aeruginosa isolates were sequenced for 23 patients during 365 days of follow-up. Recurrent presence of P. aeruginosa was seen in 19 patients (83%) and was caused by persistence of the same clonal lineage in all but one patient. We identified 38 genes mutated in parallel in two or more lineages, suggesting positive selection for adaptive mutations. Mutational enrichment analysis revealed genes important in antibiotic resistance and chronic infections to be more frequently mutated. DISCUSSION: Recurrent P. aeruginosa was common and carried for a prolonged time after initial detection in the airways of patients with COPD. Recurrence was caused by persistence of the same clonal lineage and was associated with genetic adaptation. Trial data on possible clinical benefits of attempting antibiotic eradication of P. aeruginosa in COPD are warranted.

ESBL-production in Escherichia coli and Klebsiella pneumoniae isolates from Nigeria.

The worldwide increase in infections caused by extended-spectrum beta-lactamase- (ESBL) and AmpC-producing Enterobacteriaceae (ESBL-E) is a concern. Surveillance is extensive in Europe, North America, and Asia. Yet, there is no summarizing surveillance in Africa. This study aimed to perform a preliminary investigation on the prevalence of ESBL-E in the northeastern part of Nigeria. However, of the 60 samples collected, we were able to culture 15 Escherichia coli and 7 Klebsiella spp. only. In the collection of clinical hospital samples, we found eight of 15 E. coli isolates to be ESBL (53%) and two out of seven Klebsiella spp. to be ESBL/AmpC (29%). Due to the limitations of this study, our findings cannot take a broad view on the prevalence of ESBL-E, in Nigeria and other parts of Africa. Yet, to know which genes encode ESBL in Nigeria, and to know exact prevalence of every ESBL gene would be of importance.