Predicting Oral Beta-lactam susceptibilities against Streptococcus pneumoniae

Towards pharmacokinetic boosting of phenoxymethylpenicillin (penicillin-V) using probenecid for the treatment of bacterial infections

In the face of increasing antimicrobial tolerance and resistance there is a global obligation to optimise oral antimicrobial dosing strategies including narrow spectrum penicillins, such as penicillin-V. We conducted a randomised, crossover study in healthy volunteers to characterise the influence of probenecid on penicillin-V pharmacokinetics and estimate the pharmacodynamics against Streptococcus pneumoniae. Twenty participants took six doses of penicillin-V (250 mg, 500 mg or 750 mg four times daily) with and without probenecid. Total and free concentrations of penicillin-V and probenecid were measured at two timepoints. A pharmacokinetic model was developed, and the probability of target attainment (PTA) calculated. The mean difference (95% CI) between penicillin-V alone and in combination with probenecid for serum total and free penicillin-V concentrations was significantly different at both timepoints (total: 45 min 4.32 (3.20-5.32) mg/L p < 0.001, 180 min 2.2 (1.58-3.25) mg/L p < 0.001; free: 45 min 1.15 (0.88-1.42) mg/L p < 0.001, 180 min 0.5 (0.35-0.76) mg/L p < 0.001). There was no difference between the timepoints in probenecid concentrations. PTA analysis shows probenecid allows a fourfold increase in MIC cover. Addition of probenecid was safe and well tolerated. The data support further research into improved dosing structures for complex outpatient therapy and might also be used to address penicillin supply shortages.

Community-acquired bacterial pneumonia in children: an update on antibiotic duration and immunization strategies

PURPOSE OF REVIEW

This review is structured to update clinicians on the epidemiology, antibiotic treatment, and prevention of pediatric bacterial pneumonia. The review provides information regarding the current research on antibiotic management for bacterial pneumonia and the newest immunization recommendations to prevent pneumococcal pneumonia and other respiratory infections.

RECENT FINDINGS

The recommended length of antibiotic therapy for bacterial pneumonia has been discrepant between low-income and high-income countries. Recently, randomized controlled trials conducted in high-income countries provided evidence to support a short antibiotic course (3-5 days) for uncomplicated bacterial pneumonia in otherwise healthy children. The negative impact of inaccurate penicillin allergy labels in children with pneumonia has emphasized the importance of prompt allergy de-labeling. Newer pneumococcal vaccines are recommended for children and are expected to have a significant impact on bacterial pneumonia rates.

SUMMARY

Pediatric bacterial pneumonia is an important contributor to childhood morbidity and mortality. A short antibiotic course seems to be sufficient for the outpatient management of uncomplicated bacterial pneumonia; however, more studies are required in the inpatient setting. Future studies will inform the impact of recently introduced pneumococcal and respiratory syncytial virus vaccines on the epidemiology of bacterial pneumonia.

Changes in Streptococcus pneumoniae Susceptibility in Wisconsin: Implications for Clinical Treatment Decisions for Respiratory Infections

Objective: In 2019, the American Thoracic Society and Infectious Diseases Society of America updated clinical practice guidelines for community-acquired pneumonia (CAP). In contrast to guidelines published in 2007, macrolide monotherapy for outpatients was made a conditional recommendation based on resistance levels. Local knowledge of current antimicrobial susceptibility is needed to guide management of CAP and other bacterial respiratory pathogens. The purpose of this study was to investigate antimicrobial susceptibility profiles and trending for Wisconsin Streptococcus pneumoniae isolates.Design: Multi-center laboratory surveillance, with testing at a central location utilizing standardized susceptibility testing protocols.Methods: Data published by the Wisconsin Department of Health Services (DHS) were augmented with data from the Surveillance of Wisconsin Organisms for Trends in Antimicrobial Resistance and Epidemiology (SWOTARE) program. Data were stratified by invasive or non-invasive sources, as well as DHS region and compared to data compiled from 2006-2010.Results: Susceptibility rates for ≥ 916 invasive S. pneumoniae assessed from 2016-2020 were greater than 91% for ceftriaxone, tetracycline, and fluoroquinolone agents and were generally higher than those from 354 non-invasive isolates. Low susceptibility rates were observed for invasive isolates of penicillin (78.7%) and erythromycin (64.8%) and were even lower for non-invasive isolates (73.8% and 59.9%, respectively). This erythromycin susceptibility rate was a significant reduction from that observed in 2006-2010 (80.4; P < 0.0002). 24.8% of isolates generated an erythromycin MIC ≥ 8 μg/mL. Statewide geographic variability was noted.Conclusions: Rates of S. pneumoniae susceptibility to parenteral penicillins and cephems, and oral tetracycline and fluoroquinolone agents, remain high throughout Wisconsin. However, low oral penicillin susceptibility rates, taken together with declining macrolide susceptibility rates, should cause clinicians to consider alternative treatment options for respiratory tract infections, especially with macrolides.