A patient from the Himalayas. Ocular trauma. Negative KOH. Sterile bacterial cultures. Growth detected on day 10 — only because someone didn't throw the plate away.
01Why should you care about a mould you've probably never seen?
Fungal keratitis accounts for 20–60% of all culture-positive corneal infections in South and Southeast Asia. Most of the time it's Fusarium or Aspergillus — they grow fast, they're recognisable, and you've seen them before. You know what to do.
Scopulariopsis brevicaulis? You probably haven't encountered it. The global case literature for keratitis due to this organism runs to a handful of papers. It grows slowly, looks like a contaminant, and resists most of what you'd reach for empirically.
That's precisely why it matters. The cases that trip us up aren't the common ones — they're the rare ones where laboratory behaviour breaks our assumptions. Let's walk through exactly what happens when this organism lands on your bench.
02Meet the organism
Scopulariopsis lives in soil. It is a saprophyte — ecologically useful and clinically irrelevant, until trauma happens. Its primary clinical territory is onychomycosis, where it accounts for a subset of cases that don't respond to azoles. Keratitis is vanishingly rare. When it shows up in an eye, it's almost always after injury: agricultural, industrial, construction.
Colony morphology
On Sabouraud dextrose agar, it comes up as cream to buff, powdery, granular colonies with feathery margins. Growth is moderate — typically between 7 and 14 days. While Fusarium and Aspergillus flag at days 3–5, Scopulariopsis is turning up at day 10 — exactly the window when plates in a busy lab might be discarded.
Microscopic morphology
Under LPCB (lactophenol cotton blue) mount at ×40, the defining feature is the annellide — a specialised conidiogenous cell that releases conidia sequentially, leaving ring scars at its tip. Conidia are broadly pyriform to globose, with a truncated (flat) base and a roughened, echinulate wall that becomes more pronounced with maturity.
Under LPCB at ×40, look for conidia with a rough, echinulate wall and a truncated (flat) base — like a tiny peg. The conidiogenous cell is an annellide: it releases conidia sequentially, leaving ring scars (annulations) at the tip. This is not a phialide.
Why it matters: annellide ≠ phialide. If you stop at "hyphae and conidia" and report this as Fusarium, the patient gets natamycin monotherapy — and may not recover.
Table 1 — Morphological comparison of common keratitis moulds
| Feature | Scopulariopsis brevicaulis |
Fusarium spp. | Aspergillus spp. |
|---|---|---|---|
| Colony colour | Cream to buff, powdery | White/cream, cottony | Species-dependent (green, black, yellow) |
| Growth rate on SDA | Moderate — 10–14 days | Rapid — 3–5 days | Rapid — 3–5 days |
| Conidiogenous cell | Annellide (ring scars) | Phialide (collarette) | Phialide (chains from metulae) |
| Conidia shape | Globose, rough-walled, truncated base | Banana-shaped macroconidia | Round to oval, smooth |
| KOH in keratitis | Often negative | Usually positive | Usually positive |
03The diagnostic traps — and how to avoid them
Trap 1: the negative KOH
Initial KOH was negative in the Kamboj et al. case — consistent with the broader Scopulariopsis keratitis literature. Slow-growing moulds produce fewer hyphal elements in corneal tissue at early stages, and a single scraping may not capture them.
A negative KOH does not exclude fungal keratitis. It is a signal to hold your cultures longer — not to close the case. In the correct context (ocular trauma + hypopyon + sterile bacterial cultures), continue antifungal empiric therapy and keep the plates.
Trap 2: discarding plates too early
Standard protocols require a minimum of 4 weeks before a fungal culture is signed out as negative. In practice, plates sometimes go at 5–7 days if nothing has grown. For Fusarium, this is usually fine. For Scopulariopsis, day 10 is when the colonies first appear.
The diagnosis in this case was entirely contingent on the plate being held. Discarded at day 7 — this patient would have had "culture-negative keratitis" and suboptimal empiric treatment.
Trap 3: the contaminant dismissal
Scopulariopsis is everywhere — soil, plants, construction dust. When it grows on a corneal scraping plate, the immediate reflex is often: contaminant. That reflex is wrong in the right clinical context. Before dismissing it, ask:
- Ocular trauma present?
- Hypopyon on examination?
- Bacterial cultures sterile?
- Growth on multiple plates or at the inoculation site?
All four arrows pointing the same way — it's not a contaminant.
Don't just report the organism and walk away. Call the ophthalmologist. Explain that this is not a routine mould, that standard natamycin monotherapy is insufficient, and what the MIC data mean for prescribing. This is where microbiology becomes clinical.
04Treatment: why your usual antifungals won't cut it
Scopulariopsis is intrinsically resistant to most antifungal agents that work well in other fungal keratitis. Sandoval-Denis et al. (JCM, 2013) — the most comprehensive in vitro susceptibility dataset for this genus — found high MICs for amphotericin B, itraconazole, and most echinocandins across clinical isolates.
Table 2 — Antifungal susceptibility against Scopulariopsis brevicaulis
| Agent | MIC range | Activity | Clinical note |
|---|---|---|---|
| Voriconazole | 0.5 – >16 mg/L | Variable; best available | Preferred agent for topical therapy |
| Natamycin 5% | Not standardised | Limited | Excellent for Fusarium; insufficient as monotherapy here |
| Amphotericin B | >4 – >16 mg/L | Poor | High MICs; multiple case failures documented |
| Itraconazole | >4 mg/L | Poor | Adjunct use reported; limited evidence |
| Terbinafine | 0.03 – 0.5 mg/L | Promising in vitro | Almost no keratitis clinical data |
Voriconazole as the agent of choice
Among available agents, voriconazole 1% topical demonstrates the lowest and most consistent MICs against Scopulariopsis in vitro, and its ocular pharmacokinetics are well established for fungal keratitis.
In the Kamboj et al. case, the treatment sequence was:
- Empiric phase: natamycin 5% + voriconazole 1% topical, six times daily
- After species identification: voriconazole 1% monotherapy continued
- Duration: 45 days after identification — with clinical improvement
- Outcome: mild residual visual impairment; no recurrence at follow-up
Resolution of hypopyon and apparent stabilisation are not mycological cure. Extended therapy — weeks to months — is the norm for Scopulariopsis keratitis. Surveillance for relapse should continue beyond the point of apparent clinical resolution.
A note on natamycin
Natamycin 5% remains the correct empiric first-line for fungal keratitis in South Asian settings. There is nothing wrong with starting it while cultures are pending — it covers Fusarium, the dominant pathogen. The problem arises if it is continued as monotherapy after Scopulariopsis is identified. At that point, the susceptibility data should drive a change. The identification is not academic.
05What the literature tells us
The global case literature for Scopulariopsis keratitis is small enough that individual cases matter:
| Authors & year | Key finding |
|---|---|
| Lotery et al. (1994) | Treated successfully with topical amphotericin B after molten lead injury |
| Ragge et al. (1990) | Failed both amphotericin B and itraconazole — required penetrating keratoplasty |
| Malecha (2004) | Farmer, wire injury — responded to natamycin, illustrating strain-level susceptibility variability |
| Ghosh et al. (2016) | Identified Scopulariopsis in a North Indian keratitis series |
| Roy et al. (2017) | Two cases over six years at a northern Indian tertiary centre |
| Kamboj et al. (2026) | Northern Himalayan case; incidental dacryoadenitis on CT (causal link unconfirmed) |
Taken together, these cases confirm one thing: there is no single reliable treatment for this organism. Susceptibility varies strain to strain. The in vitro data guide — but they do not guarantee. Voriconazole is the best starting point, but close clinical monitoring is essential.
06Five things to walk away with
⚠️ Educational content only — not clinical advice. All case details are from Kamboj et al., Cureus 2026;18(4):e106303. For individual patient management, apply content in the context of your local guidelines and clinical microbiologist consultation.