Basis for nebulized antibiotics: droplet characterization and in vitro antimicrobial activity versus Staphylococcus aureus, Escherichia coli, and Pseudomonas aeruginosa

Comparison of two-drug combinations, amikacin/tigecycline/imipenem and amikacin/tigecycline/clarithromycin against Mycobacteroides abscessus subsp. abscessus using the in vitro time-kill assay

Nontuberculous mycobacteria include 198 mycobacterial species. Among these, Mycobacteroides abscessus is a rapidly growing mycobacteria that causes lung and skin infections. M. abscessus lung infections are difficult to treat due to the high levels of resistance to several classes of antibiotics. The current treatment is based on combining at least two or three antibiotics. However, treatment outcomes remain very poor. The objective was to compare the in vitro activity of amikacin, tigecycline, imipenem, and clarithromycin, alone and in two different three-drug combinations (amikacin/tigecycline/imipenem and amikacin/tigecycline/clarithromycin) against seven M. abscessus subsp. abscessus clinical isolates using the time-kill assay. The two combinations showed greater activity than the antibiotics tested individually. Even though both combinations showed similar activity as well as no antagonistic activity, the combination including imipenem could not be an alternative treatment against M. abscessus subsp. abscessus lung infections caused by clarithromycin susceptible isolates. However, this combination could be considered against clarithromycin resistant isolates. Future studies are necessary to confirm this hypothesis.

Aerosol Route to Administer Teicoplanin in Mechanical Ventilation: In Vitro Study, Lung Deposition and Pharmacokinetic Analyses in Pigs

BACKROUND

Glycopeptides given intravenously achieve low airway concentrations. Nebulization of teicoplanin may be an efficient way of delivering a high concentration of this antibiotic to the lung. This multistep study assessed the feasibility of teicoplanin nebulization during mechanical ventilation by evaluating: the stability of its antibiotic effect; epithelial tolerance; lung deposition and systemic absorption in ventilated pigs.

METHODS

Nebulized and non-nebulized teicoplanin activity was tested on Staphylococcus aureus cultures. The cytotoxic effect of teicoplanin on human respiratory epithelial cells was assessed by measuring lactate dehydrogenase activity released, cell viability, and transepithelial electrical resistance. Volume median diameter of particles of nebulized teicoplanin was measured by laser diffraction during mechanical ventilation. The deposited mass of teicoplanin nebulized with a vibrating mesh nebulizer in ventilated piglets was assessed by scintigraphy. Blood pharmacokinetics of teicoplanin administered either intravenously or by nebulization was compared.

RESULTS

No decrease of antibiotic activity was observed after nebulization. In vitro cytotoxicity of teicoplanin was only observed with 1000 times the dose recommended for intravenous administration. Volume median diameter of particles was 2.5±0.1 μm. Of the initial nebulizer charge of teicoplanin, 24±7% was present in the lungs of ventilated pigs after the nebulization. Amount absorbed in blood was low (3.4%±0.9%) after nebulization, and blood stream elimination half-life value was 25.4 h.

CONCLUSIONS

Teicoplanin was administered efficiently by nebulization during mechanical ventilation, without any effect on its pharmacological properties or any cytotoxicity. The pharmacokinetic parameters are promising in view of its time-dependent killing process. All the results of our multi-step study highlighted the potential of teicoplanin to be nebulized during mechanical ventilation.

Delivering antibiotics to the lungs of patients with ventilator-associated pneumonia: an update

Ventilator-associated pneumonia is a serious hospital-acquired infection, with 20-70% crude mortality and 10-40% estimated attributable mortality. Insufficient antibiotic concentrations at the infection site when these drugs are given intravenously may lead to poor outcomes, particularly when difficult-to-treat pathogens are responsible; for example, Pseudomonas aeruginosa, extended spectrum beta lactamase-producing Gram-negative bacilli, Acinetobacter spp. and/or methicillin-resistant Staphylococcus aureus. Direct drug delivery to the infection site via aerosolization combined with intravenous administration achieves concentrations exceeding MICs of the pathogens, even those with impaired susceptibility. Experimental and recent clinical results demonstrated our markedly improved ability to deliver aerosolized antibiotics to the lung with new-generation devices, for example, vibrating-mesh nebulizers. Convincing clinical data from a large randomized trial are still lacking to support the routine administration of aerosolized antibiotics to treat ventilator-associated pneumonia, even though some small-randomized trials' observations are encouraging.

Clinical experimentation with aerosol antibiotics: current and future methods of administration

Currently almost all antibiotics are administered by the intravenous route. Since several systems and situations require more efficient methods of administration, investigation and experimentation in drug design has produced local treatment modalities. Administration of antibiotics in aerosol form is one of the treatment methods of increasing interest. As the field of drug nanotechnology grows, new molecules have been produced and combined with aerosol production systems. In the current review, we discuss the efficiency of aerosol antibiotic studies along with aerosol production systems. The different parts of the aerosol antibiotic methodology are presented. Additionally, information regarding the drug molecules used is presented and future applications of this method are discussed.