Microbiology and Parasitology: Zoonoses, Mycobacteria, Spirochetes, and Intracellular Bacteria

Comprehensive vocabulary flashcards covering zoonotic bacteria, mycobacterial infections, spirochetes, Chlamydia, and Rickettsiae based on microbiology lecture materials.

Brucella abortus

A zoonotic bacterium whose natural reservoir is cows, causing undulating fever and secondary manifestations such as community-acquired pneumonia, sinusitis, otitis media, and meningitis.

Undulating Fever

An unstable, fluctuating (up-and-down) fever pattern characteristically associated with Brucella abortus infection.

Brucella abortus Transmission

Acquired primarily through the ingestion of contaminated dairy products or direct contact with infected animals.

Brucella abortus Secondary Complications

Serves as the second most common cause for community-acquired pneumonia (CAP), sinusitis, otitis media, and meningitis.

Brucella abortus Treatment

A combination antibiotic regimen consisting of Streptomycin and Tetracycline.

Francisella tularensis

A zoonotic bacterium maintained in small wild animals that causes tularemia in humans through vector bites, direct contact, ingestion, or inhalation.

Francisella tularensis Reservoirs

Rabbits, deer, and rodents.

Ulceroglandular Tularemia

The clinical form of tularemia acquired from handling contaminated carcasses or arthropod bites, marked by an ulcer at the site of infection followed by swollen, painful regional lymph glands.

Glandular Tularemia

A form of tularemia contracted through infected arthropod bites or carcass handling, characterized by swollen and painful lymph glands without the development of cutaneous ulcers.

Oculoglandular Tularemia

A localized form of tularemia resulting from direct contamination of the eye, producing pain, redness, swelling, discharge, and occasionally an ulcer on the inside of the eyelid.

Oropharyngeal Tularemia

A clinical form acquired through eating or drinking contaminated food or water, or inhaling aerosols, causing sore throat or tonsillitis, vomiting, diarrhea, and cervical lymphadenopathy.

Pneumonic Tularemia

A respiratory form caused by inhaling aerosolized F. tularensis or secondary hematogenous spread to the lungs, presenting with sore throat, lung lymph node swelling, fever, chills, dry cough, and progressive weakness.

Typhoidal Tularemia

A form of tularemia with an unspecified route of infection characterized by systemic illness (fever, chills, headache) without localized symptoms or designated primary infection sites.

Septic Tularemia

The most severe and potentially fatal form of tularemia with an unspecified route, wherein the patient appears toxic and can develop confusion, sepsis, and coma.

Francisella tularensis Pharmacotherapy

Antimicrobial therapy consisting primarily of Streptomycin or Gentamicin.

Yersinia pestis

The Gram-negative bacterium responsible for plague, maintained within wild rodent reservoirs and transmitted via rat fleas or respiratory droplets.

Yersinia pestis Reservoirs

Wild rodents, particularly raccoons and skunks.

Yersinia pestis Transmission

Transmitted to humans through the bite of an infected rat flea or via inhalation of infectious respiratory droplets.

Buboes

Markedly inflamed, painful, and enlarged lymph nodes characteristic of bubonic plague, typically located in the inguinal region.

Hemoptysis in Pneumonic Plague

Coughing up blood resulting from severe pulmonary hemorrhage caused by Yersinia pestis infection of the lungs.

Yersinia pestis Treatment

Standard antimicrobial regimen utilizing Streptomycin or Tetracycline.

Mycobacterium tuberculosis

An obligate aerobic, acid-fast bacillus with a high-lipid waxy cell wall that causes pulmonary and extrapulmonary tuberculosis in humans.

Mycolic Acid

Lipid components present in the cell wall of Mycobacterium tuberculosis responsible for acid-fastness and resistance to chemical disinfectants.

Wax D

A lipophilic, lipid-rich component of the Mycobacterium tuberculosis cell wall that contributes to its virulence and resistance properties.

Lowenstein-Jensen Medium

An egg-based selective culture medium used specifically for cultivating Mycobacterium tuberculosis.

Acid-Fast Stains for M. tuberculosis

Staining methods, specifically Ziehl-Neelsen and Kinyoun acid-fast bacillus (AFB) stains, that identify mycobacteria based on their retention of carbolfuchsin.

M. tuberculosis Tissue Tropism

The upper lobes of the lungs, preferred because of the high oxygen content required by this strictly aerobic bacterium.

Pulmonary Tuberculosis Cardinal Symptoms

A chronic cough lasting $\ge 2$ weeks, low-grade fever, night sweats, chills, abrupt weight loss, malaise, fatigue, anorexia, and hemoptysis.

Miliary Tuberculosis

A disseminated hematogenous form of extrapulmonary tuberculosis characterized by tiny millet-seed lesions throughout organs, notably the spleen.

Scrofula

Extrapulmonary tuberculosis infection presenting as chronic tuberculous lymphadenitis of the cervical lymph nodes.

Pott's Disease

Extrapulmonary tuberculosis involving the spine, causing vertebral destruction and deformity.

Tuberculous Meningitis

A severe extrapulmonary manifestation of tuberculosis characterized by infection and inflammation of the meninges.

2HRZE / 4HR Regimen

The standard first-line treatment regimen for drug-susceptible tuberculosis consisting of a 2-month intensive phase (HRZE) and a 4-month continuation phase (HR).

Intensive Phase TB Regimen

A 2-month induction therapy consisting of Isoniazid (H), Rifampicin (R), Pyrazinamide (Z), and Ethambutol (E).

Continuation Phase TB Regimen

A 4-month maintenance therapy following the intensive phase, consisting of Isoniazid (H) and Rifampicin (R).

Bacillus Calmette-Guérin (BCG) Vaccine

An attenuated vaccine that mainly protects children against severe, disseminated forms of tuberculosis, such as TB meningitis and miliary TB.

AFB Sputum Smear Microscopy

A screening diagnostic test for tuberculosis requiring the microscopic examination of 3 consecutive early-morning sputum specimens.

Xpert MTB/RIF

A rapid molecular diagnostic test that identifies Mycobacterium tuberculosis DNA and detects mutations conferring rifampicin resistance.

Mantoux Tuberculin Skin Test (PPD)

An intradermal screening test measuring delayed-type hypersensitivity induration following the injection of Purified Protein Derivative.

Positive PPD Cutoff: Low-Risk Individuals

An induration diameter measurement of $> 15\text{ mm}$.

Positive PPD Cutoff: High-Risk Individuals

An induration diameter measurement of $> 10\text{ mm}$.

Positive PPD Cutoff: Immunocompromised Individuals

An induration diameter measurement of $> 5\text{ mm}$.

Mycobacterium leprae

An aerobic, acid-fast bacillus with tropism for cooler body tissues and peripheral nerves that causes leprosy (Hansen's disease).

Mycobacterium leprae Natural Reservoirs

Humans and nine-banded armadillos.

Paucibacillary (PB) Leprosy Regimen

Multidrug therapy for patients with few bacteria (tuberculoid form), consisting of Rifampicin and Dapsone administered for 6 months.

Multibacillary (MB) Leprosy Regimen

Multidrug therapy for patients with abundant bacteria (lepromatous form), consisting of Rifampicin, Dapsone, and Clofazimine administered for 12 months.

Tuberculoid Leprosy (TT)

A benign, localized form of leprosy seen in patients with strong cell-mediated immunity, characterized by few well-demarcated dry patches, little tissue destruction, and low transmission.

Lepromatous Leprosy (LL)

A severe, multibacillary form of leprosy seen in patients with suppressed cell-mediated immunity, presenting with diffuse skin nodules, significant tissue destruction, and high transmission.

Lepromin Test

An intradermal skin test that is positive (reactive) in tuberculoid leprosy due to intact cellular immunity and negative (nonreactive) in lepromatous leprosy.

Leonine Facies

A characteristic lion-like facial appearance with thick, nodular dermal infiltration seen in lepromatous leprosy.

Claw-Shaped Hands

A physical disfigurement resulting from peripheral nerve infiltration and destruction in lepromatous leprosy.

Pendulous Ear Lobes

Gross elongation and nodular thickening of the earlobes characteristic of advanced lepromatous leprosy.

Saddle Nose in Leprosy

Depression or collapse of the nasal bridge resulting from bacterial destruction of nasal cartilage and bone in lepromatous leprosy.

Mycoplasma pneumoniae

The smallest self-replicating bacterium ($\approx 0.1\text{--}0.3\,\mu\text{m}$) that lacks a peptidoglycan cell wall and incorporates sterols into its cell membrane.

Sterol-Containing Bacterial Cell Membrane

A unique structural characteristic of Mycoplasma species that provides osmotic stability in the absence of a peptidoglycan cell wall.

PPLO / Eaton's Medium

An enriched culture medium supporting the growth of Mycoplasma pneumoniae, which forms characteristic 'fried egg' colonies.

Atypical (Walking) Pneumonia

An insidious pulmonary infection characterized by a dry cough, low-grade fever, and mild systemic symptoms, commonly caused by Mycoplasma pneumoniae.

Cold-Agglutinin Hemolytic Anemia

An autoimmune extrapulmonary complication of Mycoplasma pneumoniae infection caused by IgM antibodies directed against erythrocyte I antigens.

Mycoplasma pneumoniae Treatment

Macrolide antibiotics such as Azithromycin, Clarithromycin, or Erythromycin.

Treponema pallidum

A thin, coiled microaerophilic spirochete transmitted sexually or transplacentally that causes syphilis.

Warthin-Starry Stain

A silver-impregnation histology stain used to visualize thin spirochetes such as Treponema pallidum in tissue specimens.

Hutchinson's Teeth

Notched, peg-shaped central incisors characteristically observed as a manifestation of congenital (neonatal) syphilis.

Chancre

A painless, non-tender indurated ulcer that develops at the site of inoculation approximately 2 to 10 weeks following primary Treponema pallidum infection.

Secondary Syphilis

The disseminated systemic stage of syphilis appearing 1 to 3 months post-infection, characterized by condyloma lata and a generalized maculopapular rash.

Condyloma Lata

Moist, wart-like, flat papular lesions teeming with spirochetes, found in the genital and perianal regions during secondary syphilis.

Syphilitic Maculopapular Rash

A generalized secondary syphilis eruption that distinctly involves the trunk, palms of the hands, and soles of the feet.

Gumma

A chronic, destructive granulomatous lesion of tertiary syphilis that causes necrosis in skin, bone, and visceral organs.

Neurosyphilis

Central nervous system involvement by Treponema pallidum in tertiary syphilis, presenting as meningitis, tabes dorsalis, or general paresis.

Argyll Robertson Pupil

A neurosyphilitic pupillary sign; defined in the notes as pupils that do not react to accommodation (near focus) but may still react to light.

Jarisch-Herxheimer Reaction

An acute, self-limited febrile reaction with chills and myalgia occurring shortly after starting penicillin therapy due to the massive lysis of Treponema pallidum and release of inflammatory cytokines (TNF-$\alpha$, IL-6, IL-8).

RPR and VDRL

Nontreponemal serologic screening tests (Rapid Plasma Reagin and Venereal Disease Research Laboratory) used to assess disease activity and treatment response in syphilis.

FTA-Abs Test

The Fluorescent Treponemal Antibody Absorption test, a specific confirmatory serologic test that detects direct antibodies against Treponema pallidum.

Borrelia burgdorferi

A large, medically important microaerophilic spirochete that causes Lyme disease following transmission by Ixodes ticks.

Ixodes scapularis

The blacklegged deer tick that serves as the biological vector transmitting Borrelia burgdorferi to humans.

Lyme Disease Clinical Manifestations

A multisystem illness presenting with clinical features including myocarditis, meningitis, Bell's palsy, and polyarthritis.

Borrelia recurrentis

A spirochete transmitted by the human body louse (Pediculus humanus) that causes relapsing fever.

Pediculus humanus

The human body louse that transmits Borrelia recurrentis (relapsing fever) and Rickettsia prowazekii (epidemic typhus).

Leptospira interrogans

An obligate aerobic spirochete characterized by thin coils and hooked ends, excreted in animal urine and cultured on Fletcher's medium.

Fletcher's Medium

A specialized enriched semisolid culture medium used for the laboratory isolation and growth of Leptospira interrogans.

Calf Tenderness in Leptospirosis

A characteristic clinical sign of leptospirosis accompanied by fever, chills, intense headache, and risk of acute renal failure.

Weil Syndrome

The most severe form of leptospirosis, characterized by the clinical triad of jaundice, acute kidney injury, and hemorrhagic manifestations (bleeding).

Leptospirosis Mild Case Treatment

Oral Doxycycline administered at a dose of 100 mg orally twice daily for 7 days.

Leptospirosis Severe Case Treatment

Intravenous antimicrobial therapy with Penicillin G (IV) or Ceftriaxone (IV).

Chlamydia trachomatis

An obligate intracellular parasitic bacterium categorized into multiple serovars causing ocular, urogenital, and lymph node infections.

Trachoma (Serovars A-C)

A chronic keratoconjunctivitis infection of the eye caused by Chlamydia trachomatis types A through C, treated with Erythromycin.

C. trachomatis Serovars D-K Manifestations

Urogenital infections (urethritis), as well as neonatal conjunctivitis and neonatal pneumonia acquired during passage through the birth canal.

Lymphogranuloma Venereum (Serovars L1-L3)

A sexually transmitted invasive infection caused by Chlamydia trachomatis types L1 through L3, presenting with painful swollen buboes in the inguinal area.

C. trachomatis Urethritis Treatment

Standard antimicrobial therapy with Doxycycline or Azithromycin.

Chlamydia pneumoniae

An obligate intracellular organism that causes atypical walking pneumonia and is clinically associated with the development of atherosclerosis.

Chlamydophila psittaci

An obligate intracellular bacterium ($\approx 0.2\text{--}1.0\,\mu\text{m}$) with a biphasic life cycle that naturally infects the respiratory and intestinal tracts of birds.

Psittacosis (Bird Fancier's Disease)

A zoonotic infection caused by Chlamydophila psittaci transmitted through contact with infected birds, producing fever, chills, headache, and a nonproductive cough.

Elementary Body vs. Reticulate Body

The biphasic developmental forms of Chlamydiaceae, where the elementary body is the small infectious extracellular form and the reticulate body is the intracellular replicative form.

Rickettsia rickettsii

An obligate intracellular bacterium transmitted by ticks that causes Rocky Mountain spotted fever, treated with Doxycycline.

Rickettsia akari

An obligate intracellular bacterium transmitted by mites that causes rickettsialpox, treated with Doxycycline.

Rickettsia prowazekii

An intracellular bacterium transmitted by the human body louse that causes epidemic typhus, presenting with high fever ($> 102.2^\circ\text{F} / > 39^\circ\text{C}$), trunk-originating rash, confusion, stupor, and severe myalgia.

Rickettsia typhi

An intracellular bacterium transmitted by rat fleas that causes endemic (murine) typhus, presenting with dry cough, fatigue, lymphadenopathy, nausea, and vomiting lasting 10 to 12 days.

Orientia tsutsugamushi

An obligate intracellular bacterium transmitted by mites (chiggers) that causes scrub typhus, characterized by cough, rash, and an eschar at the bite site.

Coxiella burnetii

An intracellular bacterium that causes Q fever without requiring an arthropod vector for transmission, treated with Doxycycline.

Ehrlichia chaffeensis

An obligate intracellular bacterium transmitted by ticks that causes human monocytic ehrlichiosis, treated with Doxycycline.

Eschar

A characteristic red lesion or sore with a dark crusted center appearing on the skin at the arthropod bite site in scrub typhus.