A patient presented with complaints of dysphagia. On UGI Endoscopy a diagnosis of esophageal candidiasis was made. The organism obtained from the sample was cultured on a specialized media and the below findings were visible on microscopy of the culture. What phenomenon is shown below?
Correct Answer: Germ tube formation
Description: (a) Germ tube formationCandidiasis* Candidiasis MC fungal infection in humans both in HIV and non-HIV infected people.* Caused by Candida, a yeast like fungus that produces pseudohyphae.Various species of Candida include:* Candida albicans: The most common and most pathogenic species* Other rare species are C. tropicalis, C. Glabrata, C. Krusei, C. parapsilosis, C. dubliniensis, C. kejyr, and C. viswanathii.Predisposing factors that are associated with increased risk of infection with Candida include-* Physiological state: Extremes of age (infancy, old age), pregnancy* Low immunity: Patients on steroid or immunosuppressive drugs, post transplantation, malignancy, HIV* Patients on broad spectrum antibiotics suppresses the normal flora* Diabetes mellitus, febrile neutropenia and zinc or iron deficiency.Clinical ManifestationsCandida species are a part of normal flora of the skin and mucosa including gut flora. In presence of opportunistic conditions, they can cause various infections.1. Mucosal candidiasis:* Oropharyngeal candidiasis (oral thrush) presents as white, adherent, painless patches in the mouth* Candidal vulvovaginitis thin whitish curd like vaginal discharge* Balanitis and balanoposthitis (occurring in uncircumcised males)* Esophageal candidiasis* Angular stomatitis and denture stomatitis* Chronic mucocutaneous candidiasis: Seen in infants with deficient CMI, resistant to treatment.2. Cutaneous candidiasis:* Intertrigo, Paronychia and onychomycosis (fungal infection of nail)* Diaper candidiasis in infants, Perianal candidiasis* Erosio interdigitalis blastomycetica, an infection between the digits of the hands or toes* Generalized disseminated cutaneous candidiasis, seen in infants.3. Invasive candidiasis: Results from hematogenous or local spread of the fungi. Various forms are:* UTI, Pulmonary candidiasis, meningitis, osteomyelitis and Hepatosplenic and disseminated candidiasis* Septicemia (C.albicans and C.glabrate).* Ocular: Keratoconjunctivitis and endophthalmitis* Nosocomial candidiasis (mainly by C. glabrata)4. Allergic candidiasis include:* Candida Vesicular lesions in the web space of hands, similar to that of dermatophytid reaction (both conditions are together called 7D' reaction)* Other allergic reactions include: Gastritis, irritable bowel syndrome and eczema.Laboratory Diagnosis* Direct microscopy: Gram-positive oval budding yeast cells (4-6 pm size) with pseudohyphae.* Culture on SDA: Colonies are described as creamy white, smooth, and pasty with typical yeasty odor.Tests for species identification:* Germ tube test: It is also called Reynolds Braude phenomenon, specific test for C. albicans.* It is differentiated from pseudohyphae as there is no constriction at the origin.* Though the test is specific for C.albicans, it may also be positive for C. dubliniensis.Note from Author: "The germ tube formation of Candida albicans was shown in the AIIMS Question PseudohyphaeTrue hyphaeSeptaConstrictedNo constrictionOrigin of branchesConstricted and SeptateNo constriction, No septum presentGrows byBuddingApical elongationTreatment* Cutaneous candidiasis or oral thrush- DOC is topical azole* Esophageal and vulvovaginal candidiasis- DOC is oral flucconazole* Disseminated candidiasis- DOC is Amphotericin B* C.glabrata and C.krusei exhibit intrinsic resistance to azoles and are refractory to treatment with azoles.
Category:
Microbiology
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