Micro 8

Question 1

Chlamydiaeo 🤷🏻‍♀️🤷🏻‍♀️

Answer 1

.🔷 Chlamydiae cannot make their own ATP. They are obligate intracellular organisms that cause mucosal infections. 2 forms:
🔸 Elementary body (small, dense)is “Enfectious” and Enters cell via Endocytosis; transforms into reticulate body. ƒ
🔸Reticulate body Replicates in cell by fission;Reorganizes into elementary bodies.

Question 2

Chlamydia trachomatis causes and tx

Answer 2

reactive arthritis (Reiter syndrome), neonatal and follicular adult conjunctivitis A , nongonococcal urethritis, and PID.

Chlamydophila pneumoniae and Chlamydophila psittaci cause atypical pneumonia; transmitted by aerosol.

Treatment: azithromycin (favored because onetime treatment) or doxycycline (+ ceftriaxone for possible concomitant gonorrhea).

Question 3

Rocky Mountain spotted fever

Answer 3

Rickettsia rickettsii, vector is tick. Despite its

name, disease occurs primarily in the South Atlantic states, especially North Carolina. Rash typically starts at wrists A and ankles and then spreads to trunk, palms, and soles.
🔸 Classic triad—headache, fever, rash (vasculitis). Palms and soles rash is seen in Coxsackievirus

A infection (hand, foot, and mouth disease), Rocky Mountain spotted fever, and 2° Syphilis (you drive CARS using your palms and soles).

Question 4

Typhus

Answer 4

Endemic (fleas)—R typhi.

Epidemic (human body louse)—R prowazekii. Rash starts centrally and spreads out, sparing palms and soles.
Rickettsii on the wRists, Typhus on the Trunk.
And this not typhoid fever 🤒 Salmonella typhi

Question 5

Mycoplasma pneumoniae

Answer 5

🍀Classic cause of atypical “walking” pneumonia (insidious onset, headache, nonproductive cough, patchy or diffuse interstitial infiltrate).
🍀X-ray looks worse than patient. High titer of cold agglutinins (IgM), which can agglutinate RBCs. Grown on Eaton agar.

🍀Treatment: macrolides, doxycycline, or fluoroquinolone (penicillin ineffective since Mycoplasma have no cell wall).

🍀No cell wall. Not seen on Gram stain. Pleomorphic A .

🌼🌼Bacterial membrane contains sterols for stability. Mycoplasmal pneumonia is more common in patients < 30 years old.

Frequent outbreaks in military recruits and prisons.

Mycoplasma gets cold without a coat (cell wall).

Question 6

Systemic mycoses

Answer 6

All of the following can cause pneumonia and can disseminate.

All are caused by dimorphic fungi: cold (20°C) = mold; heat (37°C) = yeast. Only exception is Coccidioides, which is a spherule (not yeast) in tissue.

Systemic mycoses can form granulomas (like TB); cannot be transmitted person-to-person (unlike TB).

Treatment: fluconazole or itraconazole for local infection; amphotericin B for systemic infection.

Question 7

Histoplasmosis

Answer 7

. 🍄Macrophage filled

with Histoplasma (smaller than RBC) A
🍄Palatal/tongue ulcers, splenomegaly
🍄Histo hides (within macrophages) Bird (eg, starlings) or bat droppings Diagnosis via urine/ serum antigen

Question 8

Blastomycosis

Answer 8

🌾 Broad-based budding

of Blastomyces (same size as RBC) B
🌾 Inflammatory lung disease, can disseminate to skin/ bone Verrucous skin lesions can simulate SCC Forms granulomatous nodules
🌾 Blasto buds broadly

Question 9

Coccidioidomycosis

Answer 9

🌞 Spherule (much larger than RBC) filled with endospores of Coccidioides C
🌞 Disseminates to skin/ bone Erythema nodosum (desert bumps) or multiforme Arthralgias (desert rheumatism) Can cause meningitis
🌞

Question 10

Para-coccidioidomycosis

Answer 10

Budding yeast of

Paracoccidioides with “captain’s wheel” formation (much larger than RBC) D
Paracoccidio parasails with the captain’s wheel all the way to Latin America

Question 11

Tinea (dermatophytes)

Answer 11

Clinical name for dermatophyte (cutaneous fungal) infections. Dermatophytes include

Microsporum, Trichophyton, and Epidermophyton. Branching septate hyphae visible on KOH preparation with blue fungal stain A . Associated with pruritus.

Question 12

Tinea capitis

Answer 12

Occurs on head, scalp. Associated with lymphadenopathy, alopecia, scaling

Question 13

Tinea corporis

Answer 13

Occurs on torso. Characterized by erythematous scaling rings (“ringworm”) and central clearing C . Can be acquired from contact with an infected cat or dog.

Question 14

Tinea cruris

Answer 14

Occurs in inguinal area Often does not show the central clearing seen in tinea corporis.

Question 15

Tinea pedis

Answer 15

Three varieties:

ƒ 🍁Interdigital E ; most common ƒ 🍁Moccasin distribution F ƒ 🍁Vesicular type

Question 16

Tinea unguium

Answer 16

Onychomycosis; occurs on nails.

Question 17

Tinea (pityriasis) versicolor

Answer 17

Caused by Malassezia spp. (Pityrosporum spp.), a yeast-like fungus (not a dermatophyte despite being called tinea). Degradation of lipids produces acids that damage melanocytes and cause hypopigmented G , hyperpigmented, and/or pink patches. Less pruritic than dermatophytes. Can occur any time of year, but more common in summer (hot, humid weather). “Spaghetti and meatballs” appearance on microscopy H .

Treatment: selenium sulfide, topical and/or oral antifungal medications