Stability and antibacterial potency of ceftazidime and vancomycin eyedrops reconstituted in BSS against Pseudomonas aeruginosa and Staphylococcus aureus

Machine perfusion combined with antibiotics prevents donor-derived infections caused by multidrug-resistant bacteria

Donor infection affects organ utilization, especially the infections by multidrug-resistant bacteria, which may have disastrous outcomes. We established a rat model, inoculated with Escherichia coli or carbapenem-resistant Klebsiella pneumoniae (CRKP), to investigate whether hypothermic machine perfusion (HMP), normothermic machine perfusion (NMP), or static cold storage (SCS) combined with antibiotic (AB) could eliminate the bacteria. E. coli or CRKP-infected kidneys were treated with cefoperazone-sulbactam and tigecycline, respectively. The HMP+AB and NMP+AB treatments had significant therapeutic effects on E. coli or CRKP infection compared with the SCS+AB treatment. The bacterial load of CRKP-infected kidneys in the HMP+AB (22 050 ± 2884 CFU/g vs. 1900 ± 400 CFU/g, p = .007) and NMP+AB groups (25 433 ± 2059 CFU/g vs. 500 ± 458 CFU/g, p = .002) were significantly reduced, with no statistically significant difference between both groups. Subsequently, the CRKP-infected kidneys of the HMP+AB and SCS+AB groups were transplanted. The rats in the SCS+AB group were severe infected and euthanized on day 4 post-transplant. By contrast, the rats in the HMP+AB group were in good condition. In conclusion, HMP and NMP combined with AB seems to be efficient approaches to decrease bacterial load of infected kidneys. This might lead to higher utilization rates of donors with active infection.

An Exploratory Study of a New Vancomycin Eye Drops Formulation for Extemporaneous Compounding

Purpose

Compounded eye drop solutions of vancomycin hydrochloride have important clinical applications, such as postoperative antimicrobial prophylaxis and bacterial keratitis. There exists a plethora of data to support the use of various liquid vehicles to compound vancomycin hydrochloride eye drops. However, there are a number of limitations for implementation, especially the frequent shortage or discontinuation of the vehicle products. This study was designed to investigate the use of an OTC eye wash product as the evergreen vehicle and to evaluate the physical and chemical stability of the new formulation.

Methods

The Advance Eye Relief^® eye wash and vancomycin hydrochloride for injection vials were used to prepare 10 and 50 mg/mL vancomycin eye drop solutions. The solutions were packaged in Steri-Droppers^® bottles and stored in a freezer for 14 days followed by 28 days in refrigeration. The 14-day period of freezing was included to allow time for sterility testing. At pre-determined stability time points, samples were taken for visual inspection, pH and osmolality measurement, and analysis by a stability-indicating high performance liquid chromatography (HPLC) method.

Results

Freshly prepared vancomycin eye drops were clear, colorless, and free of particulates. The pH readings were 7.03 and 6.28 for the 10 and 50 mg/mL solutions, respectively. The osmolality of both solutions were within the range of 300-330 mOsmol/kg and considered isotonic. Initial drug concentrations of all samples were confirmed by HPLC to be within 100%-103% of the label claims. Throughout the stability study period, there were no significant changes in the appearance, pH, or osmolality of any samples. The HPLC results also confirmed that the drug concentrations in all stability samples were within 98%-101% of the initial time zero values and no significant degradation product peaks were observed.

Conclusion

A new compounded vancomycin eye drop formulation was developed to mitigate vehicle sourcing issues. This eye drop formulation was easy to prepare, exhibited satisfactory properties for ophthalmic applications, and remained stable chemically and physically when stored for 14 days in freezer followed by 28 days in refrigerator.

Stability of 5% vancomycin ophthalmic solution prepared using balanced salt solution after freezing for 90 days

PURPOSE

To evaluate the stability of 5% vancomycin ophthalmic solution prepared using balanced salt solution (BSS) and stored at -20°C in polypropylene containers.

METHODS

Six batches of vancomycin 50 mg/mL eyedrops were aseptically prepared. One bottle of each batch was analyzed immediately after preparation, and the rest were stored at -20°C and analyzed using high-performance liquid chromatography (HPLC) at 30, 60, and 90 days to test their physicochemical stability and sterility. Thereafter, bottles were removed from the freezer and stored at 5°C for 30 days, with HPLC and other analyses repeated 105 and 120 days after preparation. All samples were analyzed in triplicate. Stability was defined as the absence of particles, color variation, or changes in pH and a remaining vancomycin concentration of 90% to 110% of the initial concentration. The sterility of the ophthalmic solution was evaluated by using soybean-casein digest broth with resins; samples were incubated for 7 days and checked daily for signs of microbial growth.

RESULTS

There was no particle formation or sign of precipitation in any of the solutions throughout the duration of the study, regardless of the storage conditions. No change in color or turbidity was observed. The pH and osmolarity remained unchanged during storage at -20°C and after thawing. The vancomycin concentration remained within 10% of the initial concentration during the 90-day period of storage at -20°C and the subsequent 30 days after thawing. Sterility was preserved in all samples.

CONCLUSION

A 5% solution of vancomycin prepared using BSS was physicochemically and microbiologically stable when stored at -20°C for 90 days. After thawing, this extemporaneous formulation remained stable when refrigerated at 5°C for 30 days.

Stability and Sterility of Extemporaneously Prepared Nonpreserved Cefazolin, Ceftazidime, Vancomycin, Amphotericin B, and Methylprednisolone Eye Drops

PURPOSE

To determine in-use stability and sterility of fortified cefazolin, ceftazidime, vancomycin, amphotericin B, and methylprednisolone eye drops in a simulated inpatient setting with and without a mobile refrigerated container (MR).

METHODS

Each drug was prepared and divided into 4 groups: 1) simulated patient use with the MR group: stored at 4°C and kept in the MR during drug administration, 2) simulated patient use without the MR (NoMR) group: stored at 4°C and no MR, 3) refrigerated control group: stored at 4°C, and 4) room temperature control group: stored at room temperature. Stability and sterility data were evaluated at days 0, 4, 7, 14, 21, and 28. Linear mixed-effects model and survival analysis were performed.

RESULTS

Median time to 10% loss of concentration for in-use medications (MR/NoMR groups) was >28/27.9, 22.2/22.2, 19.4/19.4, 10.18/<4, and >28/>28 days for cefazolin, ceftazidime, vancomycin, amphotericin B, and methylprednisolone, respectively. There was no significant difference in the predicted concentration loss per day among all groups for vancomycin and methylprednisolone (all P > 0.05). For the other study medications, all room temperature control groups, the cefazolin NoMR group, and the ceftazidime NoMR group had significantly greater predicted concentration loss per day compared with the refrigerated control groups (all P ≤ 0.02). Culture results were negative for all drugs throughout the study.

CONCLUSIONS

The NoMR group showed that the drug significantly degraded rapidly for cefazolin, ceftazidime, and amphotericin B. Implementation of MR could decrease the predicted loss of concentration per day for cefazolin and ceftazidime. In vitro antimicrobial activity and sterility were retained for 28 days.

Effects of the antimicrobial peptide L12 against multidrug‑resistant Staphylococcus aureus

Methicillin‑resistant Staphylococcus aureus (S. aureus; MRSA) is one of the most common bacterial pathogens and MRSA infections are characterized by high mortality rates. Antimicrobial peptides are considered one of the most promising drugs for the treatment of resistant strains of S. aureus. The present study aimed to examine the antimicrobial activity of L12 against numerous bacterial species using the broth microdilution method. Furthermore, the synergistic effect of L12 combined with various antibacterial drugs was tested, and its antibacterial mechanism was investigated by a checkerboard assay. The alterations in bacterial morphology were detected by electron microscopy, and biofilm formation and removal were tested by crystal violet staining. The present results suggested that L12 affected the growth of gram‑positive strains, particularly S. aureus. Electron microscopy analysis suggested that L12 may target the cell membrane, and L12 increased the antibacterial activity of vancomycin and levofloxacin, exerting a synergistic effect. However, the minimal inhibitory concentrations (MICs) of L12 were not correlated with antibiotic resistance, the strains resistant to more antibiotics were not more resistant to L12. A sub‑MIC of L12 was able to inhibit biofilm formation in a dose‑dependent manner; however, concentrations of L12 ≤10 times the MIC were not sufficient to degrade previously formed biofilm. Collectively, the present study suggested that L12 may represent a novel potential therapeutic molecule for the treatment of S. aureus infections.

Stability of a 50 mg/mL Ceftazidime Eye-Drops Formulation

Background

Microbial keratitis are severe infectionsgenerally linked to risk factors. High-doses antibiotic eye-drops could be required to avoid severe complications. In such cases, hospital pharmacists are in charge of their production given the lack of such formulations on the market. The stability of these antibiotic eye-drops is generally limited to a couple of days and publications generally do not describe addition of microbial preservatives even though it is a European Pharmacopeia requirement. The aim of this study was to describe a new ceftazidime eye-drops formulation at 50 mg/mL with a antimicrobial additive, benzalkonium chloride at 0.04 mg/mL.

Methods

Physico-chemical studies of this new formulation were performed by a stability indicating HPLC-UV method validated according to ICH standards, osmolality measurements, pH monitoring and visual examinations. Antimicrobial preservative efficacy was evaluated according to the method from the European Pharmacopeia.

Results

After 75 days at −20 °C followed by 7 days at 4 °C, or after 7 days at 4 °C, the eye-drops were stable. A degradation trend was finally observed at day 14 at 4 °C.

Conclusions

A new ceftazidime eye-drops formulation is proposed with a stability of 7 days. Outpatients do not need to return to the hospital pharmacy for repeat dispensing, thus possibly improving treatment compliance.

Clinical and microbiological profile of infectious keratitis in an area of Madrid, Spain

INTRODUCTION

To study antibiotic susceptibility in bacterial keratitis (BK), its profile over 10 years and its influence on ophthalmological practice.

METHODS

Retrospective review of BK with positive corneal scraping over a 10-year period. Risk factors for keratitis, visual acuity (VA), empirical topical treatment, corneal infection characteristics and outcomes were analyzed for BK due to Staphylococcus aureus, Staphylococcus epidermidis, Streptococcus pneumoniae, Pseudomonas aeruginosa and Propionibacterium acnes.

RESULTS

389 positive corneal scrapings were collected. All Gram-positive bacteria were susceptible to vancomycin. P. aeruginosa demonstrated >90% sensitivity to the most-commonly-used topical antibiotics. Susceptibility to methicillin was 90.2% for S. aureus and 66.3% for S. epidermidis. The results of 215 patients were available. 1.9% required enucleation and 2.8% required surgical treatments. Final VA improved after treatment in keratitis due to S. aureus (p=0.026) and S. epidermidis (p=0.005). There was a correlation between S. aureus resistance to methicillin (p=0.002) and levofloxacin (p=0.043) and enucleation (20% and 10%, respectively) compared with a 0% rate of enucleation in S. aureus-susceptible keratitis.

CONCLUSIONS

BK due to S. pneumoniae is very aggressive irrespective of antibiotic sensitivity. S. aureus was frequently isolated in patients with systemic diseases. It causes severe keratitis and remains moderately resistant to methicillin and levofloxacin. For this reason, keeping vancomycin in empirical regimens is believed to be necessary.

Potency and Sterility of Fortified Tobramycin, Fortified Vancomycin, and Moxifloxacin at 4, 24, and 35°C for 14 Days

PURPOSE

To assess the potency and sterility of ophthalmic antibiotic drops commonly used in the treatment of bacterial keratitis.

METHODS

This was a basic investigation. Three drugs were tested: fortified vancomycin 25 mg/mL, fortified tobramycin 14 mg/mL, and moxifloxacin 5 mg/mL. A bottle of each was stored separately at 4, 24, and 35°C, with the potency determined by microbiological assay at 0, 7, and 14 days. Differences in potency were assessed by 2-way analysis of variance followed by a 1-way repeated-measures analysis of variance with Bonferroni post hoc testing as warranted. Sterility of drugs when handled by patients for varying periods was confirmed by culturing samples on MacConkey and sheep blood agars.

RESULTS

The concentration of fortified tobramycin and moxifloxacin remained constant over 14 days at the 3 tested temperatures. The concentration of fortified vancomycin remained constant at 4°C, but it declined by 38% ± 1% (P = 0.001) at 24°C on day 14 and by 48% ± 1% (P = 0.001) and 78% ± 3% (P = 0.0009) at 35°C on days 7 and 14, respectively. A total of 49 drops (mean, 7.3 days; range, 1-18 days) were tested for sterility, and all were negative for microbial contamination.

CONCLUSIONS

All 3 drugs remained potent at 4°C for up to 14 days. Fortified tobramycin and moxifloxacin also maintained potency for 14 days at 24 and 35°C. In contrast, fortified vancomycin lost its potency by day 14 at 24°C and by day 7 at 35°C. All in-use antibiotic drops tested were sterile. The results indicate that patients should be cautioned to store vancomycin under refrigerator or at least under cool conditions.