Otitis by Vibrio Alginolyticus: An Emerging Entity without a Defined Seasonal Pattern: Contaminated Water Exposure or Persistent Colonization?

Abstract

A significant change in the seasonal patterns of ear infections has been observed due to the modification of aquatic leisure habits, also altering the etiology of the most frequently causing otitis in its various forms of presentation. This work aims to become the largest series documenting ear infections by this bacterium, carrying out a characterization and considering the possibility that the mechanism of action occurs both through contact with contaminated waters and colonization of the middle ear.

Introduction

With the increase in migratory flows and environmental changes, a significant change in aquatic and underwater leisure habits and routines has been observed, particularly during the winter season. This phenomenon has led to a higher frequency of bathing during the colder months, breaking the traditional paradigm of associating external otitis mainly with summer. Prolonged exposure to water and humidity in this new habit dynamic, combined with winter climatic conditions, has created a favorable environment for the development of ear infections during this time of the year. This change in the seasonal pattern of external otitis presents new challenges in terms of prevention and treatment, requiring greater awareness and adaptation from health professionals and the general population.

So far, it was believed that the species Vibrio alginolyticus was not part of the usual saprophytic microbiota of the upper respiratory tract, so its acquisition generally occurred through direct contact with seawater or its derivatives. However, it was usually associated with an incubation period from aquatic immersion to the onset of symptoms, which could involve a latency between exposure and otological manifestations of up to seven months.

Case Report

We present a series of six cases diagnosed and treated in our tertiary center for ear infections over the last 10 years (2014–2024), with different forms of presentation by Vibrio alginolyticus. The demographic and diagnostic-therapeutic characteristics are collected in Table 1. This resulted in the growth of a Gram-negative bacterium with a positive oxidase test. After 24 h of incubation, it grew on thiosulfate-citrate-bile salts-sucrose (TCBS) agar. For confirmation, identification was also verified by conventional biochemical tests. Finally, the antibiotic susceptibility of the isolate was tested using the Kirby-Bauer disk diffusion method. Zone diameters were interpreted according to CLSI guidelines.

Table 1.

Summary of the demographic, diagnostic, and therapeutic data of the patients included in our study. EO: External Otitis; AMO: Acute Media Otitis; TVT: Transtympanic Ventilation Tube

PATIENT	SEX	AGE	DATE OF CONSULTATION	PRESENTATION FORM	SIDE	PREVIOUS SURGERY	ANTIBIOTIC	RESISTANCES
PATIENT 1	MALE	17	February 2024	Granulomatous EO	Left	Myringoplasty + TVT	Ciprofloxacin (otic)	Amoxicilin + Ampicilin
PATIENT 2	FEMALE	9	September 2022	Suppurative AMO	Right	Myringoplasty	Levofloxacin (oral)	Ampicilin
PATIENT 3	MALE	12	March 2019	Chronic Media Otitis	Left	Myringoplasty	Neomycin + Polimixin B (otic)	Ampicilin
PAIENT 4	MALE	16	July 2018	Granulomatous EO	Right	Myringoplasty + TVT	Neomycin + Polimixin B (otic)	Ampicilin
PATIENT 5	MALE	5	January 2015	Suppurative AMO	Right	No	Levofloxacin (oral)	Amoxicilin + Ampicilin + Cefazolin
PATIENT 6	MALE	3	September 2014	Granulomatous EO	Right	No	Ciprofloxacine (otic)	Ampicilin

Fig. 1.

Presence of granuloma in the posterior hemitympanum in the acute phase of granulomatous external otitis in one of the patients in our cohort (Fig. 1A). One week later, after completing the otic treatment, the disappearance of the granuloma can be observed, revealing the normal position of the cartilage in the anterior hemitympanum as a remnant of the myringoplasty (yellow arrow), as well as a small residual perforation in the anterosuperior quadrant (blue arrow). At one month, as shown in Fig. 3C, there is a complete closure of the tympanic perforation, maintaining an optimal state of the cartilage from the previously used myringoplasty

Of the 6 cases presented, the most frequent cause of ear manifestation was granulomatous external otitis in 50% of the cases, followed by acute otitis media in 30% and chronic otitis media in one patient. In other words, half of the patients presented middle ear involvement. Only two of them had a history of swimming before their otitic process in the 12 months before the infection. Likewise, although all presented a good response to the treatment described for 7 days, in 50% of the cases of patients who had undergone myringoplasty, patients had to be reoperated due to the failure of the previously placed graft, resulting in a new residual tympanic perforation due to Vibrio alginolyticus infection.

Discussion

Among non-cholera Vibrio species, Vibrio alginolyticus stands out as one of the less pathogenic entities, especially described in infectious processes occurring in warm countries and the Mediterranean area. To date, only 4 cases of this bacterium causing otitis in the pediatric age have been described, three of which were on the American coast and the remaining one in the Netherlands, with none reported in the Mediterranean area or in countries bathed by the Indian Ocean [1], making our work the largest series of ear infections by this bacterium in the literature. This agent, unlike other Vibrio species, rarely causes gastrointestinal tract infections and has generally been documented in episodes of conjunctivitis, bacteremia, and necrotizing fasciitis. All of them had a history of recent marine aquatic activity, which reaffirms the tendency of this bacterium to settle in oceanic waters. This is related to its ease of settling in environments with saline concentrations greater than 10%, with virulent activity based on producing hemagglutination and hemolysis [2].

However, it is striking to observe that in up to 70% of cases, patients did not report bathing in a period of at least 12 months before the onset of symptoms, judging by the month of consultation and what they explained in the anamnesis. Likewise, it can be observed that five of the six patients at some point presented an accompanying tympanic perforation, with consequent surgical repair with a retroauricular myringoplasty in four of them. However, it is of interest to highlight that, in half of the intervened cases, the ear infection manifested an average of 1.12 years after the surgical act. This opens the hypothesis of whether this bacterium is only found in a marine habitat or if it can act as a reservoir in the middle ear and produce active infections [3]. Recent studies [4] show that in tympanoplasty procedures, where the skin is worked to raise flaps, it is known that epithelial migration and self-cleaning capacity can be compromised. In addition, contact with the tympanic bone could also favor the secretion of tissue fluid, facilitating bacterial growth. In short, the manipulation of the external auditory canal, with its consequent morphological modification, can favor bacterial proliferation in patients with prior colonization of this germ and a history of surgery.

In this line, Feingold et al. [3]. hypothesized about the possibility that the middle ear could act as a reservoir for this bacterium, following an ear infection by this bacterium in a patient with transtympanic ventilation tubes (TVT) 7 months after aquatic activity in freshwater. They also reaffirmed that patients with TVT or tympanic perforations suffer more infections due to swimming in freshwater rather than in pools or the ocean, questioning the possible advantage of using earplugs in these environments.

Ear infections caused by V. alginolyticus have a clinical presentation similar to more frequently isolated pyogenic agents such as Pseudomonas aeruginosa, Staphylococcus aureus, Haemophilus influenzae, and Streptococcus pneumoniae, presenting with otalgia, a sensation of ear fullness, hearing loss, and occasionally, otorrhea and otorrhagia. Our experience is consistent with the literature in that a favorable response to antibiotic treatment based on quinolones or aminoglycosides is obtained. Likewise, it is consistent with a high rate of resistance to ampicillin, as occurs in our sample in 100% of cases, with an acceptable response profile to other antibiotics by the systemic route [5], except for two cases, which presented multiple resistances.

Conclusion

In conclusion, this study of six cases diagnosed with ear infections by Vibrio alginolyticus highlights the need to reconsider preventive practices and appropriate treatments for these unusual but clinically relevant cases. The recurrence of infection in patients previously subjected to surgical procedures, such as myringoplasty, underscores the importance of close follow-up and additional preventive measures in patients with a history of ear surgery, both in the short and medium term, even after swimming. There is a possibility that the infection may manifest even months after prolonged water exposure due to potential colonization of the middle ear.

Data Availability

The datasets used and/or analyzed during the current study are available upon reasonable request from the corresponding author.

Declarations

Ethics Approval and Consent to Participate

Only approval from the respective local ethics committee for the involved institutions was required for the researchers, as this observational study did not involve novel, invasive, or exceptional interventions. This study was designed and conducted in accordance with the ethical guidelines of the 1975 Declaration of Helsinki.

Financial Disclosure

The authors declare there are no financial conflicts of interest to disclose.

Competing Interests

The authors declare they have no competing interests.