Nestor T. Hilvano, M.D., M.P.H.
Images Copyright by Bauman, Robert. 2009. Microbiology, With
Diseases by Taxonomy , 3rd edition, Pearson Benjamin Cummings

You should be able to:
1.
State the mode of transmission for mycoses.
2.
Identify the laboratory techniques used to distinguish pathogenic fungi.
3.
Discuss briefly the clinical manifestations of common systemic fungal infections and its causative agents.
4.
Describe pityriasis caused by Malassezia furfur.
5.
Identify several emerging fungal pathogens seen among AIDS patients.
6.
Compare and contrast protozoan infections caused by
Giardia, Amoeba, Trypanosoma, Trichomonas,
Plasmodium, and Toxoplasma.
7.
Compare and contrast the three most common roundworm infections of humans.

• Mycology – study of fungi
• Mycoses – fungal infection classified as superficial, cutaneous, subcutaneous, or systemic infections
• Generally spread via inhalation, trauma, or ingestion; also by contact (candida & pneumocystis)
• Most are dimorphic - below 30˚C
(mycelia composed of hyphae); at 37˚C
(as yeast)
• Diagnosis – sabouraud dextrose agar culture;
KOH preparation ; GMS (Gomori methenamine silver) stain; direct immunofluorescent probes
• Rx – antifungal agents (amphotericin B; toxic); alternative drugs (ketoconazole, itraconazole, fluconazole)

A. Pathogenic systemic fungi
• Blastomycosis – Blastomyces dermatitidis
• Coccidiomycosis – Coccidioides immitis
• Histoplasmosis – Histoplasma capsulatum
B. Opportunistic systemic fungi
• Aspergillosis – Aspergillus fumigatus,
Aspergullus flavus
• Candidiasis – Candida albicans
• Cryptococcosis – Cryptococcus neoformans
• Pneumocystosis – Pneumocystis carinii
C. Superficial, Cutaneous, and Subcutaneous fungi – by contact or environmental exposure

• Blastomycosis dermatitidis
• Prevalent in Mississippi –
Ohio river basin
• 9X more common in male
• Inhaled dust →lung →blood
→skin and bones
• Pulmonary blastomycosis – most common
• Granuloma (cutaneous blastomycosis 60-70%)
• Osteoarticular blastomycosis
(30%)
• Spores convert to yeast forms

• Valley fever
(San Joaquin Valley
Fever)
• Coccidioides immitis
• Prevalent in Southwestern US
• Inhaled in lungs→ spores germinate into spherule
( parasitic form ) →enlarges and generate more spores
• 60% - no or mild symptoms
• Fever, chest pain, rash, and pneumonia
• Subcutaneous les ion (granular material)
• Dx – identification of spherules in KOH ; culture

• Most common fungal pathogen in humans
• Histoplasma capsulatum
• Prevalent in Ohio- Mississippi valley
• Inhaled from bird droppings
• usually asymptomatic and resolve (95%)
• Chronic pulmonary histoplasmosis, chronic cutaneous histoplasmosis, systemic or ocular histoplasmosis (5%)
* Spiny spores of H. capsulatum
Granuloma in lung
(resembles TB)

• Aspergillus flavus
• Inhalation of spores
• aflatoxin→ liver CA
• Cause pulmonary diseases (noninvasive; manifest as allergy or asthma)
• In immunocompromised
• Raised red papules and necrotic
(IV drugs users, AIDS)
- non-pulmonary (cutaneous)
- systemic (often fatal)

• Candida albicans
• Infection from superficial to systemic
- superficial → deep invasion ( low immunity )→ blood stream
(catheter, surgery, etc.)
oral thrush
- perianal in infants
• Dx - clusters of yeast and pseudohyphae
• Rx – antifungal drugs; reestablish normal flora

• Crptococcus neoformans
• Worldwide
• Affects immunocompromised
• Capsule; india ink as negative stain
• From inhaled spores or birds droppings
• Lung infection (self-limiting to chronic pneumonia)
• Meningitis (most common clinical form)
• Rx – amphotericin B

• Pneumocystis jiroveci (P. carinii)
• Common opportunistic in
AIDS
• Inhalation of droplets
• Form cysts in lungs
(pneumonia)
• Fever, dyspnea, hypoxia, sometimes cough
• Dx - shadow on Chest X ray
• Rx – trimethoprim and
Sulfanilamide

• Malassezia furfur – normal inhabitant of skin ; various superficial infections
• Pityriasis (tinea versicolor ) – depigmentation or hyperpigmentation
• Folliculitis, seborrheic dermatitis, and dandruffs
• Dx – UV illumination (pale green); KOH (budding yeast and hyphae)
• Rx – ketoconazole shampoos or topical zinc pyrithione, selenium sulfide, or propylene glycol

• Amoebiasis – Entamoeba histolytica
• Trypanosomiasis – African sleeping sickness (T. gambiense, T. brucei);
Chaga
s disease (T. cruzi)
• Giardiasis – Giardia lamblia
• Trichomoniasis – Trichomonas vaginalis
• Malaria – Plasmodium vivax, P. falciparum, P. malariae
• Toxoplasmosis – Toxoplasma gondii

• Entamoeba histolytica – phagocytic; cysts with 4 nuclei; trophozoites with pseudopodia
• MOT Fecal contamination containing cysts; travellers, refugees, immigrants
• Mild to severe diarrhea ; amebic dysentery ( bloody diarrhea )
• Form abscess in liver, spleen, lung, kidney, meninges, or brain.
• Dx – identification of cyst or trophozoites in stool or intestinal biopsy
• Rx – antiamoebic drugs (metronidazole)
• Prev – discontinue use of human waste as fertilizer; effective water Rx; good personal hygiene

• Flagellates
• African sleeping sickness –
T. gambiense, T. rhodesiense,
T. brucei
• MOT – bite from tsetse fly
(trypanosoma reproduce in gut and migrate to salivary gland)
→ to lymph and blood (parasitemia)
• Acute febrile attack
• Episodic fever with lymphadenitis
• DIC
• Progressive brain dysfunction ; fatal
• Rx – early Rx is effective
* Glossina

• Trypanosoma cruzi
• MOT – bite from blood sucking kissing bug
(kiss people on lips while asleep)
→ lymph and blood → multiplies in tissues ( pseudocysts )
• Fever, lymphadenitis
• Acute form – unnoticed
• Chronic form – up to 20 yrs. Later; myocarditis, meningitis, chronic heart disease (5% mortality)

• Giardia intestinalis (G. lamblia) – with many flagella; looks like a
“ head with face ”
• One of most common waterborne gastroenteritis in US
• Cysts form in duodenum, shed in feces → mild indigestion for days/weeks → diarrhea → chronic giardiasis (bloating, nausea, vomiting, malabsorption, weight loss )
• Rx – metronidazole

• Trichomonas vaginalis –
3-4 flagella; trophozoites, no cyst form
• Common sexually transmitted parasitic infection
• Both sexes – burning, itching sensation of genitalia, some discharge
• Vaginitis in women
• Urethritis or cystitis in men, but often asymptomatic
(ping-pong disease)
• Dx – identify trophozoites in vaginal and urethral secretions
• Rx – metronidazole
• Prev – abstinence, monogamy, condoms

• Toxplasma gondii
• Wild/ domestic mammals and birds
– major reservoirs
• Cat – definitive hosts
(protozoan reproduce sexually)
• Human infected by ingesting undercooked meat with parasites; ingestion or inhalation with contaminated soil ; can cross placental to fetus
• Fever to pneumonia, CNS damage, blindness
• Pregnant women – stillbirth, jaundice, pneumonia, myocarditis, encephalitis; death
• Lymphadenitis in healthy person
• Prev – thoroughly cooking meat; avoid contact with contaminated soil

• Plasmodium vivax
(clinical relapse) ,
P. falciparum (most deadly) , P. malariae
• Vector – Anopheles mosquitoes
• Life cycle has 3 stages
1. exoerythrocytic – sporozoites (infective stage to human) travel to liver, then rupture to release merozoites (pathogenic to human)
2. erythrocytic – merozoites infect RBC; become trophozoites and undergo schizogony to produce merozoites, some develop to gametocytes
3. sporogonic – mosquitoe ingest gametocytes (infective stage to mosquito), develop into gametes, become oocyst, divides into sporozoites, completing the cycle.
• RBC lyse to release merozoites and waste → shaking chills, high fever (104˚F), sweating
• Rx – chloroquine, pyrimethamine with sulfadoxine
• Prev – prophylactic quinine for travel to endemic places; vector control; personal protection

1. Cestodes (tapeworms) a) Taenia saginata (beef tapeworm) b) Taenia solium (pork tapeworm)
2. Trematodes (flukes) a) blood flukes – Schistosoma
(schistosomiasis) b) liver flukes – Fasciola
(liver atrophy and cirrhosis)
3. Nematodes (round worms) a) Ascaris lumbricoides
– ascariasis
(worldwide; longest/largest) b) Enterobius vermicularis
- pinworm (most common in US) c) Wuchereria bancrofti
- filaria (South America, Caribbean,
Trophics)

• Wuchereria bancrofti – threadlike ( filarial) nematode
• Infect the lymphatic system and subcutaneous tissues
• Transmitted by mosquitoes (culex, aedes, and anopheles)- ingest microfilariae from infected host, then develop into larvae in gut and migrate to salivary glands, passed to human and develops into adults
• Asymptomatics for yrs.
• Elephantiasis
(tissue enlarge and harden)
• Dx – identify microfilariae or immunoassays
• Rx – diethylcarbamazine citrate
• Prev – avoidance of mosquitoes

1. Identify the fungal agent and most common clinical manifestation/s (lesion/s) of the following: candidiasis, aspergillosis, cryptococcosis, blastomycosis, coccidiodomycosis, tinea versicolor; and histoplasmosis.
2. What fungal infection is commonly associated with AIDS
(HIV)?
3. Compare and contrast amoebiasis and giardiasis.
4. Identify the risk factors and preventative measures for
Trichomonas vaginalis infection.
5. Describes the types of helminthic worms.
6. Discuss African sleeping sickness and Chaga ’s disease.
7. Discuss malarial infection as to manner of transmission, clinical manifestations, and preventions.