(Cohn) Schipper & Stalpers, 1984
Macroscopic morphology
Colonies on potato dextrose agar at 25°C are woolly and initially white, quickly becoming gray to bray brown and then developing small black dots in the mycelium which are mature sporangia. Growth is very rapid, filling the tube or Petri wish within 2 to 3 days, however the nap or height of the colony rarely exceeds 10 mm. Growth occurs at 40 °C but fails to grow at 45 °C [2202], [531].
Microscopic morphology
Hyphae are hyaline, broad (5-15 µm), ribbon-like, irregularly branched, and aseptate to sparsely septate. Sporangiophores and rhizoids are borne from creeping aerial hyphae known as stolons. Sporangiophores (200 – 1000 µm in length) are mostly unbranched, yellowish-brown to dark brown, are produced singly or in small groups, and bear globose sporangia (40-130 µm in diameter) with slightly elongated to pyriform (pear-shaped) columellae. Sporangiospores are subglobose to slightly rhomboidal, quite uniform in size (4-6 µm in length) and smooth to slightly striated. Rhizoids (100 – 120 µm) are intensely ramified, hyaline to dark brown, and occur at the junctions of the stolons and sporangiophores (nodal). The species is heterothallic, requiring compatible mating strains for the production of zygospores [2202], [2049], [531].
Special notes
In the late 1970s and early 1980s Rhizopus microsporus var. rhizopodiformis was found contaminating adhesive bandages and several post-surgical wounds were infected with this organism [812], [300], [2398]. It has subsequently been isolated from an ulcer in human gastric carcinoma [1191], was found to be the etiologic agent in an abrupt pulmonary infection during treatment of a patient for bronchial asthma [1427], and was found in wooden sticks that were the source of a pseudoepidemic among immunocompromised patients [2318]. In 2004 Maravi-Poma et al. reported an outbreak of gastric mucormycosis in 5 ICU patients associated with the use of wooden tongue depressors in critically ill patients [1431].
FTL* in vitro susceptibility data
| AMB | ITRA | VORI | POSA |
|---|---|---|---|
| 0.25 µg/ml=4 | 1.0 µg/ml=1 | >8 µg/ml=2 | 0.5 µg/ml=2 |
| 0.5 µg/ml=4 | 2.0 µg/ml=1 | 1.0 µg/ml=3 | |
| 4.0 µg/ml=2 | 4.0 µg/ml=2 | ||
| >8.0 µg/ml=1 |
| Drug/N | AMB/8 | ITRA/5 | VORI/2 | POSA/7 |
|---|---|---|---|---|
| MIC Range | 0.25-0.5 | 1.0-8.0 | >8.0 | 0.5-4.0 |
| MIC50 | * | * | * | * |
| MIC90 | * | * | * | * |
* Fungus Testing Laboratory unpublished data (NCCLS M38-A)