We performed a 15-year retrospective study regarding children admitted to our Paediatric Emergency Department due to AM. This study provides updated information on demographics data, clinical presentation and management of AM in children from 2002 to 2016.
There are many controversies regarding the incidence of AM in the last decades. Some authors found an increase of AM incidence in the last decades [2, 8, 20, 22, 23]. They referred this event both to the selection of bacterial strains resistant to antibiotics [2, 8] and to the implementation of guidelines restricting the use of antibiotics in AOM [22]. On the contrary, other authors reported no changes in the overall number of cases of AM, despite the decrease in the antibiotic use for AOM [17, 18]. Groth et al. collected 577 AM cases from 34 Swedish Hospital during 1993–2007 and they didn’t find an increase in AM incidence [19]. According to these results, Anthonsen and colleagues performed a 10–year retrospective multicentre study in Denmark and found a stable incidence of AM [18]. We found an increasing number of subjects affected by AM during the last three years, albeit this tendency doesn’t result statistically significant. Moreover it is possible that our finding does not reflect the real pediatric AM incidence in Italy, even if it is consistent with another Italian multicentre trial including 25 hospitals [5].
There aren’t universally accepted guidelines for AM approach, but local algorithmic management. Many authors consider intravenous antibiotics sufficient to successfully treat most children with AM [3, 15], while others support the importance of routine miringotomy in order to relief from pain and prevent complications [7, 22]. In our population, we used to treat uncomplicated AM only with systemic antibiotics, in agreement with the ENT specialist, while miringotomy or mastoidectomy were reserved to patients who didn’t improve to antibiotic treatment within 48 h.
There is not a standard medical treatment for pediatric AM, however empiric antimicrobial therapy should provide coverage for the principal pathogens: S. pnuemoniae[3, 16], S. pyogenes and S. aureus (including methicillin resistant S. aureus in high prevalence areas). Therefore intravenous beta lactamase antibiotics are usually used as first line treatment, mostly as monotherapy [5, 15, 20, 24, 25], but also associated to amino glycosides [3, 26], clindamycin [7], fosfomycin [27]. According to literature [5], we used parenteral Ceftriaxone considering the low prevalence of MRSA in our population.
The positive outcome in our population supports this choice even if we have not meaningful microbiological data. In fact we isolated Streptococcus Pneumoniae in middle ear fluid only in 1/21 cultural exam and we found pneumococcal antigen in only 3/30 urine samples. Regarding other pathogens isolated, Candida species and Pseudomonas aeruginosa, we supposed that they could represent a contamination from the ear canal. In particular, Pseudomonas aeuriginosas was isolated in 3 patients from spontaneous ear discharge. Since it represents the most common pathogen for chronic suppurative AOM and the most common cause of external otitis, we suppose that it could represent a contamination from the ear canal.
As there is a better coverage in PCV immunization in our population over this 15 years period, we speculate that the rise in AM incidence could be due to the infection by pneumococcal serotypes not included in current vaccines or to pathogen other than Streptococcus Pneumoniae. A recent study showed that, since introduction of PCV7, serotype 19A emerged as principal pathogen within children with pneumococcal mastoiditis. This serotype resulted highly resistant to penicillin and macrolides and its domain remained stable even after introduction of PCV13 despite it was encompassed in this vaccine [1]. In Italy 7-valent pneumococcal conjugate vaccine (PCV7) was available since 2002 and it was added to National Immunization Program in 2006 in 21 regions. From 2010 PCV7 has been replaced by 13-valent vaccine (PCV13), which was finally inserted in the National Immunization Program 2012–2014.
In our population we knew the PCV immunization status of only 103/143 enrolled children with AM. Therefore we haven’t enough data to draw conclusions about the correlation between the rise in AM incidence and the PCV coverage. Another reason that may justify this finding is the possible increase of antibiotic resistance. We can stand that outdoor patients weren’t treated accordingly to AOM guidelines in the majority of cases; in fact amoxicillin plus clavulanic acid was the first choice for AOM therapy, instead of amoxicillin alone. The abuse of amoxicillin plus clavulanic acid might have influenced the rise of resistant pathogens, however we don’t have enough microbiological data to correctly interpret changes in pathogens and antibiotic resistance. Finally in most children with AM the disease arose after an initial AOM episode, thus the “watchful waiting strategy” recommended by the latest AOM national and regional guidelines [5, 13] may have influenced trends in paediatrics mastoiditis.
The increasing trend of AM evidenced in our population in the last decade should be cautiously taken in consideration, in fact our data are limited to a single medical center and we don’t have enough information regarding microbiological isolation or AOM episode, to identify the real reason for this variation.
Many authors reported a higher incidence of AM and its complications in younger children [19, 25, 28]. Our experience did not confirm these findings. We reported that patients older than 2 years were more frequently treated for AOM than the younger ones; moreover they referred more often AM symptoms than pre-verbal patients, due to the low ability of the toddlers to express earache or retroauricular pain. Therefore we expected that younger children may have presented a faster progression from AOM to mastoiditis or that AOM may have been misunderstood due to low ability to report symptoms. Nevertheless, we found no differences in incidence of AM and its complications between patients younger and older than 2 years. One possible explanation of our results is the variation in antibiotic dosage in AM emerged from our study. Children younger than 2 years were treated at higher dosage for mastoiditis, probably because they were more frequently feverish and they had higher levels of CRP and WBC. Since we considered fever and age < 2 years as risk factors for AM complications, we hypothesize that these risk factors had not impacted on complications’ rate due to higher antibiotics dosage in this group.
Complications’ rate reported in literature ranges from 1.9 to 35% [17, 18]. According to this data, we reported 9.5% of complicated cases, mainly represented by subperiosteal abscess. We performed radiological imaging only in case of complications’ suspicion to reduce radiation exposure and anaesthetic risk. In literature the use of radiological imaging is controversial in pediatric AM. Some authors recommend diagnostic imaging at presentation in order to confirm diagnosis and to rule out complications [24, 29]. However, as reported in literature, the outcome of treatment in series using imaging doesn’t seem to be better than series avoiding these exams. Therefore imaging could be employed only in case of prolonged or complicated course of AM [14, 18, 30].
We didn’t identify any risk factors for AM complications however we found a significant inverse relationship between retroauricular erythema and complications. We speculate that this sign may have permitted a more precocious diagnosis of AM and, therefore, a more immediate treatment.
Our study has some limitations due to its retrospective nature; in fact there was no standardization in medical charts and some findings were missing, in particular regarding historic data. Moreover we cannot locate those patients with AOM in which “watchful waiting strategy” was practiced.