4.3 External auditory canal mycosis
In addition, we also observed some patients may develop external
auditory meatus mycosis in our study. In fact, we didn‘t find any
reports about the mycosis of the external auditory canal after IT. The
possible reason is that our vertigo center admits a large number of
patients in southern China, including more than 250 meniere’s disease
patients every year. Due to the large number of patients, some rare
complications may be observed in our center.
In our study, the incidence of mycosis of the external auditory canal
after dexamethasone injection in the tympanum is higher than that of
lidocaine alone, and the most likely risk factor is dexamethasone due to
patients who were injected dexamethasone in the tympanic cavity may be
at risk for immunosuppression and opportunistic infection. Leav et
al.[13]reported a case of invasive pulmonary
aspergillosis in a patient with asthma who was treated with high-dose
inhaled fluticasone(1760mgdaily) which was significantly higher than the
standard dosage in clinical practice (440mg twice daily).This suggests
that steroid can lead to immunesuppression, and the higher the
concentration, the greater the chance of an opportunistic infection.
This is consistent with what we observed in our study, all the patients
who were infected by the fungal were treated with 5mg/ml of
dexamethasone, while patients treated with 2mg/ml showed no signs of
fungal infection. It may suggest that we should reduce the concentration
of dexamethasone as much as possible
on
the premise of ensuring the therapeutic effect.
In addition, the warm and humid environment in southern China
is one of the special factor of
fungal external auditory meatus. First of all, fungi can easily
reproduce in a warm environment. Our hospital is located in the south of
China where belongs to a subtropical region, with an average temperature
of over 22.5℃, while the appropriate growth temperature of fungi is
between 20-35℃.Secondly, Guangzhou is close to the ocean and there are
no big mountains to prevent the warm and humid air flow coming from the
ocean reaching Guangzhou. And this warm and humid environment is very
favorable for the growth of fungi[14].
The third factor may be the one that clinicians need to be urgently
concerned about is iatrogenic infections, which include the whole
treatment process is not standardized or the use of fungus-infected
drugs. If the syringe is not properly sterilized during drug extraction,
a small amount of fungal spores may be iatrogenic into the eardrum or
external auditory canal, which may cause local propagation and spread of
the fungus. Treatment with fungus-contaminated steroids is one of the
most direct causes of fungal infection. Kauffman
CA[15]found that 751 patients were reported with
fungal infection and 64died in 2012. In the end, they found that most
patients had undergone epidural injection and a few osteoarticular
injection with fungus-contaminated methylprednisolone acetate, resulting
in a significant number of intracranial and intra-articular infections.
Therefore, the government must carry out the most stringent quality
control requirements for the production of drugs.