The Effect of Antibiotic Eye Drops on the Nasal Microbiome in Healthy Subjects
Status:
Recruiting
Trial end date:
2024-07-01
Target enrollment:
Participant gender:
Summary
Ophthalmic topical antibiotics are commonly prescribed in clinical practice for several
indications such as bacterial conjunctivitis, keratitis, blepharitis, dacryocystitis and also
as prophylaxis. Aminoglycosides (i.e. gentamicin) and fluoroquinolones (i.e. ciprofloxacin)
are among the most frequently used substance classes.
There is evidence that topical non-antibiotic eye drops might have an effect on the
nasopharyngeal mucosal flora. This seems logical due to the anatomical connection through the
nasolacrimal duct and the fact that up to 80% of topically administered drug diffuse into the
systemic circulation through the highly vascularized nasopharyngeal mucosa. However, in the
literature no data on the effect of antibiotic eye drops on the nasal or pharyngeal
microbiome are currently available.
Recently, new, non-culture based techniques for assessment of the bacterial microbiome have
been developed, so-called "next-generation sequencing" (NGS). NGS utilizes universal primers
targeting the 16S rRNA gene, which is ubiquitous across most bacteria. With this technique,
it is possible to gain information about a wide range of the bacterial microbiome and not
only on pre-selected species.
In the present study, NGS will be used to investigate the effect of antibiotic eye drops on
the nasal and pharyngeal microbiome. For this purpose, healthy subjects will be randomized to
either receive eye drops containing gentamicin, ciprofloxacin or topical lubricants as
control. As secondary outcome, prevalence of bacterial resistance genes, as well as signs and
symptoms of ocular surface damage will be assessed.
The study will be carried out in 2 parts. Since both formulations of topical antibiotics
contain benzalkonium chloride which also has a potential effect on the nasal and pharyngeal
mucosal flora, it is unknown how much benzalkonium chloride would contribute to changes in
the nasal microbiome after administration of topical antibiotics. To overcome this problem,
first a pilot study in 20 subjects will be performed in which subjects will be randomized to
receive either eye drops containing gentamicin, ciprofloxacin, preservative-containing
topical lubricants or preservative-free topical lubricants. Based on the results of this
pilot study, the control for the main part of the study will be chosen, depending on the
effect on the bacterial microbiome. The results of the pilot study could also provide useful
data to adjust the sample size for the main study part. In the main study, 60 subjects will
be randomized to receive gentamicin, ciprofloxacin or lubricant eye drops. The same
examinations as described above will be performed after 1 week treatment as well as 1 week
and 3 months after treatment.