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Non-dermatophyte mold onychomycosis in Sri Lanka

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Non-dermatophyte mold onychomycosis in Sri Lanka
Ranthilaka R Ranawaka MD1, Nelun de Silva MD2, Ramya W Ragunathan MD1
Dermatology Online Journal 18 (1): 7

1. Department of Dermatology, Teaching Hospital Karapitiya, Galle, Sri Lanka
2. Department of Microbiology, University of Ruhuna, Galle, Sri Lanka


Dermatophytic and non-dermatophytic onychomycosis (NDM) was indistinguishable clinically in our case series. Making a clinical diagnosis of onychomycosis without mycology is the routine practice in Sri Lanka. The prevalence of NDM (45.8%) was very high in our patient population, followed by yeasts (34.1%); dermatophyte infection made up only 20%. Therefore, the treatment of onychomycosis with griseofulvin seems futile. Close contact with soil, the habit of walking barefoot, frequent emersion of hands in water, and a hot, humid climate partly explain the variation in causative pathogens in this case series.

Clinical cases

Figure 1Figure 2

Figure 1. 28-year-old farmer complained of black discoloration and painful swollen posterior nail folds of the great toes for 5 years and of the fingers for 3 months. Mixed growth of A. niger and Penicillium sp were isolated. Frequent contact with mud on the bare feet and hands was identified as the predisposing factor.

Figure 2. 35-year-old woman exhibited second and third left toenail onycholysis, subungual hyperkeratosis, and discoloration without paronychia, that evolved over 2 years. Surgical nail avulsion had been performed twice without improvement. Cladosporium sp was isolated. Gardening barefoot and frequent contact with water during household work were identified as possible predisposing factors.

Figure 3Figure 4

Figure 3. A 24-year-old female medical student presented with bilateral great toenail involvement for 5 years. On examination yellow green discoloration, onycholysis, and subungual hyperkeratosis were noted without paronychia. Surgical nail avulsion had been performed twice without antifungal therapy. Paecilomycis sp was isolated. Except for the barefoot gardening no other predisposing factor was identified in this case.

Figure 4. A 32-year-old woman teacher presented with nail plate thickening, discoloration and painful paronychia on both hands for 2 years duration. Fusarium sp was isolated. Being a diabetic for 1 year and frequent contact with water during household work were identified as predisposing factors. Her diabetes was under control with oral hypoglycemics.

Figure 5Figure 6

Figure 5. The patient in Figure 4 had total dystrophy of bilateral thumb nails. All affected nails were associated with painful paronychia. Fusarium sp was isolated.

Figure 6. The patient in Figure 4 had DLSO on bilateral great toenails. All affected nails were associated with painful paronychia. Fusarium sp was isolated.

Eighty-four percent of our patients had involvement of their great toes (bilateral- 59, left great toe only-7 and right great toe only-3). Toenails only were involved in 37 percent whereas fingernails only in 12 percent; the thumb nail was the most common. Both toenails and fingernails were involved in 51 percent.

Figure 7Figure 8

Figure 7. A 57-year-old clerk presented with painful discoloration of the right middle fingernail and bilateral great toenails for 8 months duration. Fusarium sp was isolated. A predisposing factor was not apparent from his history.

Figure 8. The patient in Figure 7 with painful DLSO involving bilateral great toenails for 8 months. Fusarium sp was isolated. The main site of entry by invading organisms in our case series was the distal and lateral margins (DLSO) (76%).

Figure 9

Figure 9. Total dystrophic onychomycosis with paronychia in an immunocompetent patient. Candida albicans was isolated. This nail belonged to a 53-year-old staff nurse, and only the R thumb nail was affected.

In patients with only fingernail involvement, yeasts were the most common pathogens (2 Candida albicans, 5 other Candida sp, 2 A. niger, and 1 A. terreus). Total onychodystrophy was noted in 3.9 percent (n=5).


The specimens were collected as nail clippings and subungual debris. Nail samples were microscopically studied after clearing for 3-4 hours in 40 percent KOH. For cultures 3-4 nail fragments were inoculated in Sabouraud-Dextrose-agar chloramphenicol-gentamicin medium, with and without cycloheximide. They were incubated at 28-29°C for 3 weeks. Tease mount preparation of the colonies in lactophenol cotton blue were used for generic identification of the fungal isolates. Further testing with slide cultures were done for species identification. All NDM samples were done in duplicate.

Diagnosis of NDM onychomycosis was made on the basis of the following criteria:

  • Nail abnormalities consistent with the diagnosis
  • Positive KOH preparation with presence of hyphae in the nail keratin
  • Growth of the same mold in duplicate cultures
  • Failure to isolate a dermatophyte or yeast in culture
  • Colony morphology and sporulation pattern

Significant growth was considered when both microscopy of direct mounts in KOH and culture was positive for fungi.


One hundred twenty-eight patients, 97 women and 31 men (3:1 ratio), with clinical onychomycosis were studied. Women were significantly predominant (75.8%); it is possible that men were less likely to seek treatment.

Onychomycosis was uncommon in children; 3 percent in this case series, compared to 88 percent of adults (18-65 years), and 9 percent elderly. The duration of nail dystrophy before presentation ranged from 2 months to 25 years, with the average being 4 years.

The diagnosis of onychomycosis was established in 66.4 percent of the clinically suspected patients; 20 percent of the infections were dermatophytes, 45.8 percent NDM, and 34.1 percent were Candida sp (Table 1).


In routine practice we noticed that the prevalence of NDM onychomycosis was much higher in our setting than reported in the literature. This study was conducted in an outpatient skin clinic to assess the prevalence and clinical manifestations of NDM onychomycosis. Patients with nail involvement with some form of morbidity such as pain, embarrassment over fingernail involvement, foul odor with discharging pus, or limitation in work because of pain and burning sensation were the reasons that were stated for presenting for treatment.

There was no significant fungal growth in 33.6 percent of our patients; they may have had nail dystrophy related to frequent minor trauma or had fungi that did not grow in our culture. Repeated laboratory fungal tests could eventually produce positive results in some of these. The patients who were clinically suggestive of onychomycosis were started on antifungal therapy even though the fungal tests were negative in duplicate samples [1].

In our study population, 16.25 percent were farmers and 15 percent were manual laborers who worked in paddy fields (in mud and water) and tea plantations with bare feet or in open rubber slippers. Wearing rubber boots or closed shoes were a rare practice in this group due to hot humid climate and low economy More than half (63%) had a history of frequent contact with water; of these 43 percent were women engaged in household work. In fact, 18 percent denied any predisposing factor. The majority (83%) of our patients were considered to be from the middle socio-economic group .

A. niger, A. flavus, and Fusarium are saprophytic molds, which are widely distributed as soil and plant pathogens [2, 3, 4]. Although NDM and candida can invade healthy nails, secondary colonization of previously damaged nail is common. This explains the striking results we obtained and confirmed, in contrast to studies done in temperate countries. This variation may be explained by (1) geographic differences in mold distribution, (2) differences in the criteria used for diagnosing mold onychomycosis, and (3) use of mycological methods inappropriate for mold growth. High prevalence of NDM onychomycosis has been reported from India (22%) [5] Malaysia (35.5%) [6], Thailand (51.6%) [7] and Pakistan (68%) [8], too.

In temperate zones, the most frequently isolated molds were Aspergillus sp (4% in nails, 3% in skin) and Scopulariopsis brevicaulis (3% in nails, 0.4% in skin) [3]. Aspergillus niger was the most common pathogen (22%) isolated in our study, followed by Aspergillus flavus (6%) and Fusarium sp (6%). Other Candida sp were isolated in 23.5 percent, whereas Trichosporon yeasts (8.2%) and Candida albicans (2.3%) followed (Table 1). Aspergillus niger was the most common pathogen identified in diabetics in our case series (Table 2); increased incidence of Candida or dermatophyte nail infection was not seen among them [9].

Tosti et al [2] reported that the majority (76%) of onychomycosis caused by NDM presents with paronychia. Our data support this by showing concomitant paronychia in 61 percent in the NDM infections and 38 percent in the Candida infections (Table 3).

Dermatophytic and non-dermatophytic onychomycosis were indistinguishable clinically in our case series. The clinical diagnosis of onychomycosis without mycology is routine practice in Sri Lanka. Therefore, because the prevalence of NDM (45.8%) and yeasts (34.1%) were very much higher than dermatophyte infections (20%), treatment of onychomycosis with griseofulvin seems futile [10, 11].

NDM showed a poor response to current topical, oral, or device-related antifungal therapies [12]. In the study conducted by Ranawaka et al [11], with oral itraconazole pulse therapy, even though the mycological cure was 100 percent, Fusarium sp showed only 60-70 percent clinical cure after 12 months follow-up. Gupta AK et al [13] reported that terbinafine gave the highest reported cure rates for the treatment of Scopulariopsis brevicaulis and Aspergillus species infections. A meta-analysis conducted by Yin Z et al [14] showed that the combined risk ratio comparing terbinafine with itraconazole for mycological recurrence rate was 0.44 (95% CI 0.29-0.66), which suggests that itraconazole therapy was more likely to produce mycological recurrence compared with terbinafine therapy. Topical treatment such as ciclopirox nail lacquer may also be effective (data originating from Scopulariopsis brevicaulis and Acremonium species infections), especially when combined with chemical or surgical avulsion of the nail [13, 15]. Total nail avulsion followed by topical antifungal post-operatively was an effective management option (clinical cure rate 88% and mycological cure rate 100%) for patient with single or oligo-onychomycosis [16]. Posaconazole was effective in vitro against Scytalidium dimidiatum. But it showed only partial response in the treatment of superficial scytalidiosis in the clinical trial conducted by Dunad J et al [17]. Three sessions of photodynamic therapy (with methyl-aminolevulinate) separated by 15 days has been used effectively to treat onychomycosis caused by Acremonium sclerotigenum (one case report) [18].

Finally, Amichai B et al [1] showed that, of the 147 cases of clinical onychomycosis initially thought to be negative, 138 (94%) were later found to be positive after up to four consecutive sets of laboratory mycological investigations. Therefore, suggest starting systemic antifungal treatment in patients with suspected fungal infections, even if they have negative laboratory fungal examinations may be useful in some cases.

In conclusion, clinicians must appreciate that the NDM should no longer be disregarded as pure contaminants and choose optimal antifungal agents accordingly.

ACKNOWLEDGEMENT: We thank Mr H K T A Gunasekara, technical officer at the laboratory of the Department of Microbiology, Faculty of Medicine, University of Ruhuna for his hard work during our study.


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