Topical versus systemic antibiotics for chronic suppurative otitis media

Chronic suppurative otitis media (CSOM), sometimes referred to as chronic otitis media (COM), is a chronic inflammation and often polymicrobial infection (involving more than one micro-organism) of the middle ear and mastoid cavity, characterised by ear discharge (otorrhoea) through a perforated tympanic membrane. The predominant symptoms of CSOM are ear discharge and hearing loss. Antibiotics are the most common treatment for CSOM, which act to kill or inhibit the growth of micro-organisms that may be responsible for the infection. Antibiotics can be administered both topically and systemically, and can be used alone or in addition to other treatments for CSOM such as ear cleaning (aural toileting).

To assess the effects of topical versus systemic antibiotics for people with CSOM.

The Cochrane ENT Information Specialist searched the Cochrane ENT Register; Central Register of Controlled Trials (CENTRAL via the Cochrane Register of Studies); Ovid MEDLINE; Ovid Embase; CINAHL; Web of Science; ClinicalTrials.gov; ICTRP and additional sources for published and unpublished trials. The date of the search was 16 March 2020.

We included randomised controlled trials (RCTs) with at least a one-week follow-up involving patients (adults and children) who had chronic ear discharge of unknown cause or CSOM, where the ear discharge had continued for more than two weeks. The studies compared topical antibiotics against systemic (oral, injection) antibiotics. We separated studies according to whether they compared the same type of antibiotic in both treatment groups, or different types of antibiotics. For each comparison we considered whether there was background treatment for both treatment groups, for example aural toileting (ear cleaning).

We used the standard Cochrane methodological procedures. We used GRADE to assess the certainty of the evidence for each outcome. Our primary outcomes were: resolution of ear discharge or 'dry ear' (whether otoscopically confirmed or not, measured at between one week and up to two weeks, two weeks up to four weeks, and after four weeks), health-related quality of life using a validated instrument, ear pain (otalgia) or discomfort or local irritation. Secondary outcomes included hearing, serious complications and ototoxicity measured in several ways.

Six studies (445 participants), all with high risk of bias, were included. All but two studies included patients with confirmed CSOM, where perforation of the ear drum was clearly documented. None of the studies reported results for resolution of ear discharge after four weeks or health-related quality of life. 1. Topical versus systemic administration of the same type of antibiotics (quinolones) Four studies (325 participants) compared topical versus systemic (oral) administration of ciprofloxacin. Three studies reported resolution of ear discharge at one to two weeks and found that the topical administration may slightly increase resolution (risk ratio (RR) 1.48, 95% confidence interval (CI) 1.24 to 1.76; 285 participants; 3 studies; I² = 0%; low-certainty evidence). In these studies, aural toileting was either not mentioned, or limited to the first visit. Three studies (265 participants) reported that they did not suspect ototoxicity in any participants, but it is unclear how this was measured (very low-certainty evidence). No studies reported the outcomes of ear pain or serious complications. No studies reported results for hearing, despite it being measured in three studies. 2. Topical versus systemic administration of different types of antibiotics (quinolones versus aminoglycosides) One study (60 participants) compared topical ciprofloxacin versus gentamicin injected intramuscularly. No aural toileting was reported. Resolution of ear discharge was not measured at one to two weeks. The study did not report any 'side effects' from which we assumed that no ear pain, suspected ototoxicity or serious complications occurred (very low-certainty evidence). The study stated that "no worsening of the audiometric function related to local or parenteral therapy was observed". 3. Topical versus systemic administration of different types of antibiotics (quinolones versus amoxicillin-clavulanic acid) One study compared topical ofloxacin with amoxicillin-clavulanic acid with all participants receiving suction ear cleaning at the first visit. It is uncertain if there is a difference between the two groups in resolution of ear discharge at one to two weeks due to study limitations and the very small sample size (RR 2.93, 95% CI 1.50 to 5.72; 56 participants; very low-certainty evidence). It is unclear if there is a difference between topical quinolone compared with oral amoxicillin-clavulanic acid with regards to ear pain, hearing or suspected ototoxicity (very low-certainty evidence). No studies reported the outcome of serious complications.

There was a limited amount of low-quality evidence available, from studies completed over 15 years ago, to examine whether topical or systemic antibiotics are more effective in achieving resolution of ear discharge for people with CSOM. However, amongst this uncertainty there is some evidence to suggest that the topical administration of antibiotics may be more effective than systemic administration of antibiotics in achieving resolution of ear discharge (dry ear). There is limited evidence available regarding different types of antibiotics. It is not possible to determine with any certainty whether or not topical quinolones are better or worse than systemic aminoglycosides. These two groups of compounds have different adverse effect profiles, but there is insufficient evidence from the included studies to make any comment about these. In general, adverse effects were poorly reported.