Efficacy of ceftaroline versus vancomycin in an experimental foreign-body and systemic infection model caused by biofilm-producing methicillin-resistant Staphylococcus epidermidis

Antibiofilm approaches as a new paradigm for treating infections

The lack of effective antibiotics for drug-resistant infections has led the World Health Organization to declare antibiotic resistance a global priority. Most bacterial infections are caused by microbes growing in structured communities called biofilms. Bacteria growing in biofilms are less susceptible to antibiotics than their planktonic counterparts. Despite their significant clinical implications, bacterial biofilms have not received the attention they warrant, with no approved antibiotics specifically designed for their eradication. In this paper, we aim to shed light on recent advancements in antibiofilm strategies that offer compelling alternatives to traditional antibiotics. Additionally, we will briefly explore the potential synergy between computational approaches, including the emerging field of artificial intelligence, and the accelerated design and discovery of novel antibiofilm molecules in the years ahead.

Efficacy of ceftaroline and rifampin, alone or combined, in a rat model of methicillin-resistant Staphylococcus epidermidis osteomyelitis without implant

IMPORTANCE

Methicillin-resistant Staphylococcus epidermidis (MRSE) contributes to a high percentage of orthopedic infections, and their treatment represents a huge challenge. The present study aimed to evaluate the efficacy of ceftaroline alone or combined with rifampin in a rat MRSE osteomyelitis model and the bone penetration of ceftaroline. A ceftaroline monotherapy showed a significant bacterial reduction in infected bones after a 7-day period of treatment. The combination ceftaroline plus rifampin leveraged rifampin's bactericidal activity, shortening the duration of positive culture in infected animals. These results suggest that ceftaroline and rifampin combination therapy could represent a valuable therapeutic option for human MRSE osteomyelitis and deserves further preclinical and clinical evaluation.

Identifying a therapeutic target for vancomycin against staphylococci in young infants

OBJECTIVES

To determine the therapeutic target of vancomycin in young infants with staphylococcal infections.

METHODS

Retrospective data were collected for infants aged 0 to 90 days with CoNS or MRSA bacteraemia over a 4 year period at the Royal Children's Hospital Melbourne, Australia. Vancomycin broth microdilution MICs were determined. A published pharmacokinetic model was externally validated using the study dataset and a time-to-event (TTE) pharmacodynamic model developed to link the AUC of vancomycin with the event being the first negative blood culture. Simulations were performed to determine the trough vancomycin concentration that correlates with a 90% PTA of the target AUC24.

RESULTS

Thirty infants, 28 with CoNS and 2 with MRSA bacteraemia, who had 165 vancomycin concentrations determined were included. The vancomycin broth microdilution MIC was determined for 24 CoNS and 1 MRSA isolate, both with a median MIC of 1 mg/L (CoNS range = 0.5-4.0). An AUC0-24 target of ≥300 mg/L·h or AUC24-48 of ≥424 mg/L·h. increased the chance of bacteriological cure by 7.8- and 7.3-fold, respectively. However, AUC0-24 performed best in the pharmacokinetic-pharmacodynamic model. This correlates with 24 to 48 h trough concentrations of >15-18 mg/L and >10-15 mg/L for 6- and 12-hourly dosing, respectively, and can be used to guide vancomycin therapy in this population.

CONCLUSIONS

An AUC0-24 ≥300 mg/L·h or AUC24-48 ≥424 mg/L·h was associated with an increase in bacteriological cure in young infants with staphylococcal bloodstream infections.

Activity of Different Antistaphylococcal Therapies, Alone or Combined, in a Rat Model of Methicillin-Resistant Staphylococcus epidermidis Osteitis without Implant

We developed a rat model of methicillin-resistant Staphylococcus epidermidis (MRSE) osteitis without implant to compare the efficacy of vancomycin, linezolid, daptomycin, ceftaroline, and rifampin either alone or in association with rifampin. A clinical strain of MRSE was inoculated into the proximal tibia. Following a 1-week infection period, rats received either no treatment or 3, 7, or 14 days of human-equivalent antibiotic regimen. Quantitative bone cultures were performed throughout the 14-day period. The mean ± SD quantity of staphylococci in the bone after a 1-week infection period was 4.5 ± 1.0 log10 CFU/g bone, with this bacterial load remaining stable after 3 weeks of infection (4.9 ± 1.4 log10 CFU/g bone). Vancomycin monotherapy was the most slowly bactericidal treatment, whereas ceftaroline monotherapy was the most rapidly bactericidal treatment. The addition of rifampin significantly increased the bacterial reduction for vancomycin, linezolid, and daptomycin. All tibias were sterilized after 2 weeks of treatment except for animals receiving vancomycin or daptomycin alone (66.6% and 50% of sterilization, respectively). These results show that ceftaroline and linezolid alone remain good options in the treatment of MRSE osteitis without implant. The combination with rifampin increases the antibiotic effect of vancomycin and daptomycin lines.

Antibacterial Activity of Colloidal Silver against Gram-Negative and Gram-Positive Bacteria

Due to the emergence of antimicrobial resistance, new alternative therapies are needed. Silver was used to treat bacterial infections since antiquity due to its known antimicrobial properties. Here, we aimed to evaluate the in vitro activity of colloidal silver (CS) against multidrug-resistant (MDR) Gram-negative and Gram-positive bacteria. A total of 270 strains (Acinetobacter baumannii (n = 45), Pseudomonas aeruginosa (n = 25), Escherichia coli (n = 79), Klebsiella pneumoniae (n = 58)], Staphylococcus aureus (n = 34), Staphylococcus epidermidis (n = 14), and Enterococcus species (n = 15)) were used. The minimal inhibitory concentration (MIC) of CS was determined for all strains by using microdilution assay, and time-kill curve assays of representative reference and MDR strains of these bacteria were performed. Membrane permeation and bacterial reactive oxygen species (ROS) production were determined in presence of CS. CS MIC₉₀ was 4-8 mg/L for all strains. CS was bactericidal, during 24 h, at 1× and 2× MIC against Gram-negative bacteria, and at 2× MIC against Gram-positive bacteria, and it did not affect their membrane permeabilization. Furthermore, we found that CS significantly increased the ROS production in Gram-negative with respect to Gram-positive bacteria at 24 h of incubation. Altogether, these results suggest that CS could be an effective treatment for infections caused by MDR Gram-negative and Gram-positive bacteria.

Evaluation of the clinical relevance of vancomycin for the treatment of Lyme disease

Vancomycin is active in vitro and in vivo in mouse systems against Lyme disease borrelia; however, there are no published data on the efficacy of vancomycin in patients with Lyme disease and no convincing theoretical advantages of vancomycin over the currently used and highly effective orally administered antimicrobial agents, including doxycycline, amoxicillin and cefuroxime axetil. In addition, vancomycin may cause a wide variety of potentially serious adverse effects and requires the placement of an intravenous catheter. It is concluded that vancomycin is a much less attractive option for the treatment of patients with early Lyme disease (or any other manifestation of Lyme disease), compared with the antimicrobials currently being used. Based on available evidence, clinical studies to evaluate the safety and efficacy of vancomycin for Lyme disease cannot be recommended.