7. Infectious disease

Question 1

Failure to thrive, lymphadenopathy, opportunistic infections (eg Pneumocystis pneumonia, thrush) in infancy suggests what? How do you confirm the dx?

Answer 1

HIV in infancy (dec CD4 T cells)

PCR reaction testing confirms dx.

Question 2

Group A strep pharyngitis (Fever, tonsillar exudate,s tender anterior cervical lymphadenopathy). Next step if suspected in a child vs adult?

Answer 2

Always confirm with rapid strep test or throat culture bf starting abx. Penicillin and amoxicillin is preferred tx.
Note: adults who meet all Centor criteria (fever, ant cervical lymphadenopathy, tonsillar exudates, no cough) can receive abx w/o testing.

Question 3

In HIV patients, when can patients receive a live attenuated vaccine and when can they not?

Answer 3

Can get vaccine: Immunocompetent (CD4 >200)

Cant get vaccine: immunocompromised (CD4 <200)

Question 4

Fever, hypotension, diffuse red macular rash involving palms and soles in a female a few days after period started? Tx?

Answer 4

TSS - staph aureus exotoxin release

Tx - fluid replacement and abx

Question 5

What is the most approp step in management if ventilator-assoc pneumonia is suspected?

Answer 5

Gram stain and culture of resp secretions

Usually VAP dev >48 after intubation

Question 6

HIV positive patient with MRI showing ring-enhancing mass in periventricular area. Serology positive for toxoplasma. PCR shows EBV DNA. Dx?

Answer 6

Primary CNS lymphoma

Note: positive toxoplasma is common in normal subjects - not specific for toxo.

Question 7

Infection with what organisms should you suspect in IV drug users presenting with pulm sx, and cavitary lesions in lungs?

Answer 7

Staph aureus - septic pulmonary embolism from infective endocarditis of tricuspid valve.

Question 8

Fever, toxicity, pharyngitis with possible grey-white exudate, sandpaper-like rash, in child is suspicious for what?

Answer 8

Scarlet fever - GAS

Tx - penicillin V

Question 9

Erysipelas (skin infx of the upper dermis and superficial lymphatics) is most commonly caused by what infection?

Answer 9

Group A strep.
Sx - fever, chills, regional lymphadenitis. Involvement of external ear is particularly suggestive of erysipelas (this skin lacks lower dermis level), making cellulitis (deeper skin infx) less likely.

Question 10

Acute febrile rxn <12 h after initial tx of early syphilis. Sx include fever, HA, myalgias, rigors, sweating, hypotension, and worsening syphilitic rash. Dx?

Answer 10

Jarish-Herxheimer rxn due to rapid lysis of spirochetes. Self-limited

Question 11

What are the 3 phases of bordetella pertussis?

Answer 11

1. catarrhal - mild cough/rhinitis (1-2wk)
2. paroxysmal - severe paroxysms of coughing and posttussive emesis (2-6wk)
3. convalescent - sx resolve gradually (wk-mo)

Question 12

A patient with CD4 count 30/mm3 and excruciating pain with swallowing is likely to have candida albicans or viral esophagitis?

Answer 12

Viral is more likely. HSV and CMV common. Dx with endoscopy with bx. Candida would have mild to moderate pain with swalling and oral thrush

Question 13

How else can pregnant women acquire toxoplasmosis aside from cat feces?

Answer 13

ingestion of raw or undercooked meat.
Infants are asymp at birth by experience chorioretinitis in adulthood. If symptomatic at birth they may have macrocephaly, diffuse intracerebral calcifications, and hydrocephalus.

Question 14

What are some extrahepatic manifestations of chronic hep C?

Answer 14

Derm: porphyria cutanea tarda (vesicles and bullae with trauma or sun exposure), lichen planus
Heme; mixed cryoglobulinemia syndrome (palpable purpura, arthralgias, low complement)
Glomerulonephritis

Question 15

When treating pneumocystis pneumonia in an HIV pos patient, in addition to TMP-SMX, why d you add corticosteroids?

Answer 15

Corticosteroids have been shown to dec mortality in severe PCP. Indications for corticosteroids include PaO2 <=70 or A-a gradient >=35 on room air.

Question 16

How often should the following vaccines be given in patients >=65yo?

1. PCV13
2. PPSV23
3. Influenza vaccine

Answer 16

1. PCV13 is rec for all adults >=65, folowed by the 23 at least 6-12mo later
2. Influenza annually to all adults
   Note: PPSV23 alone is recommended for adults <54 who are current smokers or have chronic medical conditions

Question 17

Patients with CF are prone to pneumonia caused by what organism in the following ages?

1. 0-20yo
2. 20->45yo

Answer 17

1. S aureus (more common in infants and young kids)

2. Pseudomonas aeruginosa (more common in adults)

Question 18

What organism is a common cause of food-borne illness related to shellfish and wound infections related to marine environments?

Answer 18

Vibrio vulnificus - marine bacterium. Infx can be mild or can develop necrotizing fasciitis with hemorrhagic bullous lesions and septic shock.

Question 19

Does croup present with inspiratory or expiratory stridor?

Answer 19

Inspiratory (barking)

Question 20

Differentiate rash seen on the palm of HSV vs syphilis

Answer 20

HSV: herpetic whitlow; focal, unilateral, vesicular
Syphilis: secondary syphilis, symmetric, macular/papular on palms and soles.

Question 21

If lyme disease is suspected from an erythema migrans rash, what is the best next step in management?

Answer 21

Oral doxycycline. Don’t need to do serology bc too insensitive and can be seronegative. Only perform if patient has signs of early disseminated or late disease

Question 22

What are the MCC of acute, UNIilateral lymphadenitis in children (enlarged, erythematous, tender, submandibular nodules most common)?

Answer 22

S aureus, and Strep pyogenes

Note: Prevotella sp can cause this in the setting of poor dentition and caries

Question 23

What is the MCC of meningitis/neonatal sepsis in young infants? Sx? Prophy?

Answer 23

Group B strep
hyper or hypothermia, resp distress, irritable, vomit, jaundice, bulging fontanelles, apnea, seizure
Prophy: maternal screening before delivery and with intrapartum abx. Note: only works for early onset GBS, not late onset (>7 days)

Question 24

Why shouldn’t you give ampicillin or amoxicillin to a patient with mono?

Answer 24

Development of polymorphous, maculopapular rash

Question 25

How is the CSF analysis of Guillain-Barre syndrome different than other bacterial, fungal, or viral CSF?

Answer 25

GBS: CSF shows high protein with normal WBC (albuminocytologic dissociation)
Bacterial/fungal: high protein, high WBC, low glucose
Viral: normal/high protein, high WBC, normal glucose

Question 26

Tetanus toxoid-containing vaccine only is given to all patients with possible tetanus exposure, except when the wound is ___ and the patient ____. In this case you give the vaccine PLUS tetanus immunoglobulin

Answer 26

Dirty/severe wound and pt is unimmunized, uncertain, or if they have not previously received at least 3 tetanus toxoid vaccine doses.

Question 27

What is the MC sequelae of bacterial meningitis in kids?

Answer 27

Hearing loss

Other: intellectual injury, cerebral palsy, learning disabilities, and seizure do.

Question 28

Major cause of diarrhea in patients with HIV who have CD4 counts:

1. <180
2. <100
3. <50

Answer 28

1. Cryptosporidium (low-grade fever)
2. Microsporidium/isosporidium (fever rare)
3. MAC (high fever)
4. CMV (low-grade fever, hematochezia)

Question 29

How do you evaluate for pneumocystis pneumonia if it is suspected?

Answer 29

Must ID the P jirovecii organism

1. induced sputum
2. bronchoscopy/bronchoalveolar lavage if induced sputum is inadequate

Question 30

Prolonged high fever (min response to antipyretics), irritable, systemic inflam, conjunctivitis, strawberry tongue, cerv LAD, asian. Tx? Complications?

Answer 30

Kawasaki - vasculitis
Tx: aspirin
Complications: Coronary artery aneurysms, MI, ischemia

Question 31

Are most deep, long-standing diabetic wounds polymicrobial or monomicrobial? If there is underlying osteomyelitis is it due to hematogenous or contiguous spread?

Answer 31

Polymicrobial

Contiguous spread

Question 32

Patients with new dx of HIV should be tested for latent TB.

In general, if PPD is positive in a nonsymptomatic patient, how do you treat the latent TB?

Answer 32

9 mo isoniazid and pryidoxine to prevent peripheral neuropathy

Question 33

In a vignette of a man who has sex with a man and oral thrush, this is a sign of CD4 count of what?

Answer 33

CD4 count <200

Question 34

What is the MC vaccine-preventable disease among travelers and should be considered if traveling to developing countries?

Answer 34

Hep A

Question 35

What should be considered in patients with a liver abscess who have lived or traveled in an endemic area (eg mexico).

Answer 35

Amebiasis (entamoeba histolytica)
Tx: metronidazole
Cyst drainage is not recommended routinely

Question 36

What organisms are responsible for most deep infx following puncture wounds?

Answer 36

S aureus and pseudomonas

Note: C tetani does not cause osteomyeltiis, but there can be risk of tetanus after puncture wounds

Question 37

Acute, unilateral cervical lymphadenitis in children is usually caused by what organism?

Answer 37

Bacteria: MC is S aureus. GAS is next.

Question 38

Meningitis in kids. In what age group does GBS occur in vs N meningitidis?

Answer 38

GBS is MC in neonates (<3mo)

N meningitidis >3mo. Assoc with meningeal sins and petechial/purpuric rash

Question 39

What’s the MC predisposing factor for acute bacterial sinusitis?

Answer 39

viral URI