Case of Gentamicin ototoxicity due to over dose? the case from Thinadhoo Regional Hospital

A 3 year old girl from G. Dh Thinadhoo has turned deaf following treatment for a middle ear infection at Thinadhoo Regional Hospital. The child was seen by Pediatrician stationed at TRH Dr Pavel and diagnosed as a case of Otitis Media (infection of the middle ear cavity).

Family member reported to MMW that child was prescribed antibiotics including Gentamicin. Gentamicin is a drug that is commonly used for significant infections caused by Gram Negative Bacteria (a special group of infection causing bacteria that are known to cause middle ear infections). Child also reportedly had 2 surgeries performed on her ear in 3 days.

During treatment parents reported noticing that the child was not responding to sounds as she used to. Initially they discounted this to be due to the ear infection. Dr Pavel had assured the family that the hearing would improve following treatment.

With the infection completely cleared child continued to have difficulty hearing. Parents were worried and had the child taken to Male' for further medical care. ENT specialist Dr Mauroof from IGMH reportedly told parents that the deafness was permanent and that it was caused by Gentamicin (which is known to have ototoxic side effects) being used in inappropriately high doses. The child has since then been taken abroad and deafness (sensorineural hearing loss due to ototoxic injury from Gentamicin overdose) confirmed.

We consulted a Maldivian pediatrician, who wished not to be named, at his clinic who confirmed that Gentamicin is known to cause ototoxic deafness in a few patients who are prescribed it. The senior pediatrician also told us that he believed that the dose used was too high. [We counter checked the dose from BNF and found that the dose was in fact unusually high. She was prescribed 80mg three times a day. This is significantly higher than the recommended dose for the 16 kg girl. The recommended total daily dose is 7.5mg/kg/day, this would be a total daily dose of 120 mg not 240mg that was given].

The pediatrician said to us that he thought that the medicine could have been an acceptable choice, but was used inappropriately. He also noted that warning signs of ototoxicity were ignored and treatment continued while the child was having significant warning signs. He also suspects that the double surgery could also have contributed to the deafness.

We at MMW understand that Gentamicin is a commonly used and useful antibiotic that has probably saved millions of lives worldwide. The ototoxic deafness caused by it is not very common, but is described even in the most basic pharmacology texts. We believe that ototoxicity may have been caused even if the correct dose was used (this is described in Gentamicin prescribing information sheets) but fail to understand why such a large dose was used and why the treatment was continued even when toxicity was noted. Did the doctor not know the dosage? Was this an error in calculating or writing? If an error, why was it not detected by nursing staff? Why were the warning signs ignored?

A useful medicine has been brought to disrepute in this case. It is however, not the medicine that is to blame. Caution is advised in using the medicine in patients with kidney diseases and hearing impairment AND warnings issued about its continued use when toxic signs are noted.

We at MMW feel that the responsibility lies with the prescribing doctor and the institution and hope that the child is compensated appropriately. She has been prescribed treatment that could help bring back hearing, the cost of such treatment should be borne by the state or the institution or doctor that was at fault.