Answer: Rickettsia rickettsii, tick bite, doxycycline
Answer: The patient here has pelvic inflammatory disease (PID). The causal organism is C. trachomatis, an intracellular parasite that is unable to make adenosine triphosphate (ATP). PID includes endometritis, salpingitis, tubo-ovarian abscess, and pelvic peritonitis. PID increases the risk of infertility as well as ectopic pregnancies.
Answer: Most likely nongonococcal urethritis caused by C. tmchomatis serotypes D-K. However, treat for all likely causes of urethritis—either doxycycline or azithromycin for C. trachomatis and Ureaplasma urealyticum, and ceftriaxone for N. gonorrhoeae.
Answer: It is transmitted by aerosols rather than an arthropod vector, is not associated with a rash, and the Weil-Felix reaction is negative.
Answer: Self-limited flu-like illness, soaking sweats, pneumonia, and can cause hepatitis and endocarditis. Note that there is no rash
Answer: Q fever. Spreads by inhalation of endospores from placental products of animals
Answer: Tetracyclines (eg, doxycycline)
Answer: Rickettsia akari carried by mites that causes an initial red papule at the bite site, and eventually chickenpox-like vesicles over the body
Answer: Fever, headache, rash from Rickettsia typhi (less severe than epidemic typhus) spread by rodent-fleas from a rodent reservoir.
Note that found in urban areas in the United States
Answer: Fever, headache, rash due to Rickettsia prowazekii. Transmitted at times of overcrowding (poverty, war) by human body lice. Characteristic rash consists of pink macules; starts centrally and spreads outward sparing the palms and soles.
Answer: On the ankles and wrists and palms and soles and then spreads to the trunk, and face (centripetal spread)
Answer: Fever, headache, conjunctival redness, and petechial rash on palms and soles due to Rickettsia rickettsii. RMSF is transmitted by wood tick bites and is actually more common in the eastern United States.
Answer: A test for antibodies to Proteus vulgaris antigens used to diagnose rickettsial infection based on the coincidental cross-reactivity with Rickettsia (except C. burnetii)
Answer: Rash (vasculitis), high fever, severe headache
Answer: Through arthropod vectors (except Q fever, Coxiella burnetii was previously classified as a Rickettsia)
Answer: Erythromycin eye drops
Answer: Tetracycline, doxycycline, erythromycin, azithromycin, or a fluoroquinolone
Answer: Aerosol transmission
Answer: Intimal changes with deposition of lipid-laden macrophages, resulting in a fatty streak.
Note that the significance of C. pneumoniae in the pathogenesis of atherosclerosis remains unclear.
Answer: Atypical pneumonia (gradual onset of fever and nonproductive cough, eosinophilia, history of conjunctivitis)
Answer: Psittacosis, an atypical pneumonia occurring after exposure to infected birds
Answer: Serology and PCR. In the past, a skin test using antigen, prepared from Chlamydia and known as the Frei test, was used.
Answer:
Primary: painless, self-limited genital ulcer
Secondary: acute inguinal adenitis (Buboes) due to lymphatic spread of infection
Chronic disease may develop resulting in further ulceration, proctocolitis, rectal strictures, rectovaginal fistulas, and elephantiasis.
Answer: Reactive arthritis
Answer: A sequela of cervicitis due to C. trachomatis (or Neisseria gonorrhoeae) infection. Spread of the infection to the fallopian tubes and ovaries leads to fallopian tube scarring, and risk of infertility and ectopic pregnancy.
Answer: Urethritis and cervicitis caused by C. trachomatis
Answer: Because of the existence of multiple serotypes, there is no lifelong immunity to Chlamydia as reinfection with another serotype is a frequent occurrence.
Answer: Nongonococcal urethritis (men) and cervicitis/PID (women), both sexually transmitted. Inclusion conjunctivitis (newborns) and infant pneumonia, both transmitted during delivery through infected birth canals
Answer: Trachoma, a chronic conjunctivitis that can lead to corneal scarring (most common cause of preventable blindness worldwide)
Answer: Chlamydia Gram stains quite poorly because it is an intracellular pathogen.
Answer: Basophilic intracytoplasmic inclusion bodies within epithelial cells are visualized with Giemsa stain or fluorescent antibodies. Also with PCR and serology
Answer: It lacks muramic acid, therefore, all β-lactam antibiotics are ineffective against Chlamydia.
Answer:
Elementary body is extracellular and infectious
Reticulate body is intracellular and dividing (replicating)
Answer: In living cell S. Rickettsia and Chlamydia cannot be cultured on nonliving media because they need to steal adenosine triphosphate (ATP) from living cells to survive.
Mnemonic:
Rob Cells of ATP (Rickettsia, Chlamydia)
Answer: Chlamydia and Rickettsia
Answer: Lyme disease caused by B. burgdorferi. Treat with doxycycline.
Answer: The patient has tertiary syphilis with injury to the dorsal columns of the spinal cord caused by T. pallidum.
Answer: Treponema pallidum is still exquisitely sensitive to benzathine penicillin.
Answer: Penicillin or doxycycline
Answer: Water contaminated with infected urine of dogs, rats, livestock, and wild animals
Answer: Severe leptospirosis with renal failure, hepatitis, jaundice, mental status changes, and multiorgan hemorrhage
Mnemonic:
Organs in alphabetical order KLM (Kidneys, Liver, Mind)
Answer:
First (leptospiremic) phase: high spiking temperatures, headache, and severe muscle aches
Second (immune) phase: recurrence of leptospiremic symptoms with meningismus
Answer: Antigenic variation: B. recurrentis changes its surface proteins to evade the immune system.
Answer: Doxycycline or erythromycin
Answer: 3- to 6-day episodes of high fever, headaches, myalgias, followed by approximately 8 afebrile days, and then 3- to 6-day relapses of fever. Relapses progressively shorten with longer afebrile periods.
Answer: Relapsing fever
Answer: Doxycycline, amoxicillin (for children <8 for whom Doxy is contraindicated), or a third-generation cephalosporin
Mnemonic:
GEt a BAD LIMP W/Borrelia (Giemsa stain, EM, Bell palsy, AV block, Doxycycline, Lyme disease, Ixodes, Migratory arthritis/Meningitis, Penicillin, Wright stain)
Answer: Encephalopathy (impaired memory, somnolence) and migratory autoimmune arthritis
Answer:
Systemic: fever, malaise
Neurologic: aseptic meningitis, Bell palsy, peripheral neuropathy
Cardiac: transient AV block, myocarditis Large joints: brief attacks of arthritis (eg, the knee)
Dermatologic: multiple disseminated EM lesions
Answer: A red, circular, macular rash that spreads with a red advancing border and a clear central region, giving a bull's-eye or target appearance
Answer: Erythema migrans (EM) and nonspecific flu-like symptoms
Like syphilis, there are three stages:
1. Primary localized stage (erythema migrans)
2. Disseminated stage
3. Late chronic stage
Answer: Summer
Answer: In the northeastern, midwestern, and northwestern United States (also endemic in Europe). Named after Lyme, Connecticut, where it was first reported
Answer: By insect vector, the Ixodes tick, from a mouse reservoir
Answer: Borrelia burgdorferi is seen by light microscope with Giemsa or Wright stain S. Borrelia are much bigger than other spirochetes and do not require dark-field microscopy.
Mnemonic:
Borrelia are Big
Answer: Lyme disease
1. Primary: a painless papule develops into a yaw (a large wart-like lesion).
2. Secondary: disseminated yaws of varying appearance that frequently ulcerate and may involve palms and soles.
3. Tertiary: widespread bone and soft tissue destruction.
Answer: Treponema pertenue causes yaws.
Answer: Fever, malaise/headache, and myalgias that can occur at the onset of syphilis treatment due to pyrogens released from killed organisms
Answer: Viral infections (Epstein-Barr virus [EBV], hepatitides), Drugs, pregnancy, Rheumatic fever, Rheumatoid arthritis, Lupus, and Leprosy
Answer: VDRL and RPR are highly sensitive but have low specificity.
Answer: Specific: FTA-ABS and MHA-TP test for antibodies against T. pallidum. These are the first serologic tests to become positive and remain positive after treatment.
Nonspecific: VDRL and RPR tests for antibodies are associated with the infection and become negative with treatment.
Answer: Venereal Disease Research Laboratory (VDRL), rapid plasma reagin (RPR), the fluorescent treponemal antibody-absorbed (FTA-ABS), and the Microhemagglutination Assay-Treponema Pallidum (MHA-TP)
Answer: Penicillin (The particular type and dosing of the penicillin depends on the stage of the disease.)
Answer: Snuffles (bloody nasal discharge), saddle nose, saber shins (bowing of the tibia), Hutchinson teeth (widely spaced, notched upper incisors), rash, neurosyphilis with eighth nerve deafness
Mnemonic:
Syphilis RASH (Snuffles, Saddle nose, Rash, Auditory [deafness], Saber shins, Hutchinson teeth)
Answer: A feature of tertiary syphilis, it is a pupil that constricts during accommodation but not in response to light (ie, prostitute's pupil)
Mnemonic:
GeT A SCAR w/Treponema (Gummas, Tabes dorsalis, Aortic aneurysm, Syphilis, Chancre, Argyll Robinson, Rash)
Answer: A form of neurosyphilis presenting with insidious psychiatric symptoms (irritability, apathy) and progressing to a severe dementia
Answer: Syphilitic damage to the posterior columns and dorsal roots of the spinal cord with impairment of position and vibration sense. May result in broad-based gait ataxia and a positive Romberg test
Answer: Stroke without hypertension in an individual with a history of sexually transmitted diseases (STDs)
Answer: Aseptic meningitis (predominantly lymphocytes in cerebrospinal fluid [CSF]), meningovascular syphilis (vascular damage leading to cerebrovascular occlusion or infarction), tabes dorsalis, and general paresis
Answer: Classically a thoracic aneurysm forms in the ascending aorta or aortic arch leading to aortic insufficiency or dissection.
Answer: Soft, non-cancerous granulomatous growths of tertiary syphilis
Answer: After 6 to 40 years
Answer: Gummatous syphilis, cardiovascular syphilis, and neurosyphilis
Answer: In the first 2 years (early latent), 25% may relapse to secondary syphilis. Over many years, 30% may progress to tertiary syphilis.
Answer: Latent syphilis occurs after secondary syphilis has resolved. All patients are asymptomatic with a positive blood test for syphilis without any signs or symptoms of disease.
Answer: The bacteremic/disseminated stage with systemic symptoms (fever, weight loss, etc), a classic maculopapular rash often involving the palms and soles, and condyloma latum (warty lesion) in warm moist areas (groin, skin folds)
Answer: Ulcerating, painless lesion that is highly infectious
Answer: A painless chancre that may be accompanied by nontender swelling of regional inguinal lymph nodes (groin adenitis)
Answer: Primary (3-6 weeks after initial infection), secondary (~6 weeks after resolution of primary chancre), latent (after resolution of secondary), tertiary (6-40 years after infection)
Answer: Sexually or transplacentally
Answer: Syphilis
Answer: On dark-field microscopy
Answer: Mnemonic: Borrelia, Leptospira, Treponema BLT
Answer: Nocardia. Remember to keep Nocardia in the differential for a cavitary lung lesion in an immunocompromised patient.
Answer: Nocardia asteroides, trimethoprim-sulfamethoxazole (TMP-SMX)
Answer: Actinomyces, penicillin
Answer: Actinomyces israelii, penicillin
Answer: Ureaplasma has urease, and can split urea to ammonia and CO2.
Answer: Urethritis with dysuria and clear mucoid discharge. Treat with tetracycline macrolide or a tetracycline.
Answer: In the normal flora of the lower urinary tract of 60% of sexually active women
Answer: Pneumonia is self-limiting, but macrolides or tetracyclines can shorten the course.
Answer: On Eaton agar
Answer: Infection leads to production of antibodies against M. pneumoniae antigens, resulting in a positive cold agglutinin test.
Answer: Inhalation of respiratory droplets
Answer: A community-acquired pneumonia usually caused by M. pneumoniae in which the radiologic findings appear much worse than the patient's symptoms
Answer: "Walking pneumonia" in teenagers and young adults
1. Mycoplasma pneumoniae (Eaton agent)
2. Ureaplasma urealyticum
Answer: They are the smallest free-living organisms capable of self-replication.
