Local antibiotics or antibiotics that target the whole body: which works better to treat chronic suppurative otitis media (persistent or recurring ear infection with discharge)?

Why is this question important?

Chronic suppurative otitis media (CSOM), also known as chronic otitis media (COM), is an inflammation and infection of the middle ear that lasts for two weeks or more. People with CSOM usually experience recurrent or persistent discharge – fluid that leaks out from a hole or tear in the eardrum – and hearing loss.

Antibiotics (medicines that fight bacterial infections) are the most common treatment for CSOM. Antibiotics can:

- be applied to part of the body (locally) in the form of drops, sprays, ointments or creams (topical antibiotics); or
- treat the whole body (systemic antibiotics) when injected, or taken orally (by mouth).

To find out whether topical or systemic antibiotics are better for treating CSOM, and whether they have different adverse (unwanted) effects, we reviewed the evidence from research studies.

How did we identify and evaluate the evidence?

First, we searched the medical literature for studies that followed adults or children with CSOM for at least one week and compared:

- the topical and systemic forms of the same antibiotic; or
- a topical antibiotic against a different, systemic antibiotic.

We then compared the results and summarised the evidence from all the studies. Finally, we rated our confidence in the evidence, based on factors such as study methods and sizes, and the consistency of findings across studies.

What did we find?

We found six studies that involved a total of 445 people. People were treated with antibiotics for between five days and two weeks, and were followed for up to 21 days. Studies were conducted in Spain (three studies), Italy (two studies) and Hong Kong (one study). Three studies provided information about how they were funded or who supplied medicines: one study received funding from a university, and medicines were provided by pharmaceutical companies in two studies.

Studies compared:

- quinolone ear drops against oral quinolone (four studies);
- quinolone ear drops against injected aminoglycosides (one study);
- ofloxacin ear drops against oral amoxicillin-clavulanic acid (one study).

Quinolone ear drops compared to quinolone taken orally

Compared to oral quinolone, quinolone ear drops may slightly increase the chances of ear discharge resolving after one to two weeks. We do not know if there is a difference between the two treatments for:

- hearing;
- ear pain;
- serious complications such as facial palsy (weakness of the muscles in the face);
- meningitis (an inflammation of fluid and membranes in the brain); or
- ototoxicity (when a person develops hearing or balance problems due to a medicine).

This is because either no studies reported information about these effects, or we have too little confidence in the evidence available.

Quinolone ear drops compared to injected aminoglycosides

We do not know if quinolone ear drops are better or worse than injected aminoglycosides for treating CSOM. Only one study investigated this and it provided insufficient robust evidence.

Ofloxacin ear drops against oral amoxicillin-clavulanic acid

We do not know if ofloxacin ear drops are better or worse than oral amoxicillin-clavulanic acid for treating CSOM. Only one study investigated this and it provided insufficient robust evidence.

No study reported information about the effects of different treatments on ear discharge after four weeks or health-related quality of life.

What does this mean?

Topical antibiotics may be more effective than systemic antibiotics at resolving ear discharge. We do not know whether systemic or topical antibiotics are better for improving hearing. We need more evidence from robust studies to be able to compare the effects of topical and systemic antibiotics on aspects such as health-related quality of life or ear pain. We also need more information about adverse effects.

How up-to-date is this review?

The evidence in this Cochrane Review is current to March 2020.

Authors' conclusions: 

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.

Read the full abstract...
Background: 

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).

Objectives: 

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

Search strategy: 

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.

Selection criteria: 

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).

Data collection and analysis: 

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.

Main results: 

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.

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