Infectious Disease Flashcards Preview

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Flashcards in Infectious Disease Deck (131):
1

Specify which bugs are associated with UTIs and what empirical antibiotic should be used while waiting for culture results

Escherichia coli

Treatment: TMP-SMX, nitrofurantoin, amoxicillin, quinolones

2

Specify which bugs are associated with bronchitis and what empirical antibiotic should be used while waiting for culture results

Virus, Haemophilus influenzae, Moraxella spp.

Treatment: Usually no benefit from antibiotics. May consider macrolides or doxycycline

3

Specify which bugs are associated with pneumonia (classic vs atypical) and what empirical antibiotic should be used while waiting for culture results

Classic: Streptococcus pneumoniae, H. influenzae

  • treatment: Third-generation cephalosporin, azithromycin

Atypical: Mycoplasma, Chlamydia spp.

  • treatment: Macrolide antibiotic, doxycycline

4

Specify which bugs are associated with osteomyelitis and what empirical antibiotic should be used while waiting for culture results

Staphylococcus aureus, Salmonella spp.

Treatment: Oxacillin, cefazolin, vancomycin

5

Specify which bugs are associated with cellulitis and what empirical antibiotic should be used while waiting for culture results

Streptococci, staphylococci

Treatment: Cephalexin or dicloxacillin. TMP-SMX, doxycycline, or clindamycin are often used as first-line agents because of the emergence of MRSA

6

Specify which bugs are associated with meningitis (child) and what empirical antibiotic should be used while waiting for culture results

Streptococci B, E. coli, Listeria spp.

Treatment: Ampicillin + aminoglycoside (usually gentamicin); an expanded spectrum third-generation cephalosporin (cefotaxime) should be added if a gram-negative organism is suspected

7

Specify which bugs are associated with meningitis (child/adult) and what empirical antibiotic should be used while waiting for culture results

S. pneumoniae, Neisseria meningitidis*

Treatment: Cefotaxime or ceftriaxone + vancomycin

8

Specify which bugs are associated with endocarditis (native vs prosthetic valve) and what empirical antibiotic should be used while waiting for culture results

Endocarditis (native valve) - Staphylococci, streptococci

  • Treatment: antistaphylococcal penicillin (ex: Oxacillin, nafcillin) or vancomycin if allergic to penicillin + aminoglycoside

Endocarditis (prosthetic valve) - Numerous different organisms

  • Treatment: Vancomycin + gentamicin + cefepime or a carbapenem

9

Specify which bugs are associated with sepsis and what empirical antibiotic should be used while waiting for culture results

Gram-negative organisms, streptococci, staphylococci

Treatment: Third-generation penicillin/cephalosporin + aminoglycoside, or imipenem

10

Specify which 3 bugs are associated with septic arthritis and what empirical antibiotics should be used while waiting for culture results

S. aureus -> Vancomycin

Gram negative bacilli -> Ceftazidime or ceftriaxone

Gonococci -> Ceftriaxone, ciprofloxacin, or spectinomycin

11

Specify which empirical antibiotic should be used for Streptococcus A or B while waiting for culture results

1st line: Penicillin, cefazolin

Alternative(s): Erythromycin

12

Specify which empirical antibiotic should be used for S. pneumoniae while waiting for culture results

1st line: Third-generation cephalosporin + vancomycin

Alternative(s): Fluoroquinolone

13

Specify which empirical antibiotic should be used for Enterococcus while waiting for culture results

1st line: Penicillin or ampicillin + aminoglycoside

Alternative(s): Vancomycin + aminoglycoside

14

Specify which empirical antibiotic should be used for Staphylococcus aureus while waiting for culture results

1st line: Anti-staphylococcus penicillin (e.g., methicillin)

Alternative(s): Vancomycin, TMP-SMX, doxycycline, clindamycin, or linezolid for MRSA

15

Specify which empirical antibiotic should be used for Gonococcus while waiting for culture results

1st line: Ceftriaxone

Alternative(s): Cefixime or high-dose azithromycin followed by test of cure in 1 week

16

Specify which empirical antibiotic should be used for Meningococcus while waiting for culture results

1st line: Cefotaxime or ceftriaxone

Alternative(s): Chloramphenicol or penicillin G if proven to be penicillin susceptible

17

Specify which empirical antibiotic should be used for Haemophilus while waiting for culture results

1st line: Second- or third-generation cephalosporin

Alternative(s): Amoxicillin

18

Specify which empirical antibiotic should be used for Pseudomonas while waiting for culture results

1st line: Antipseudomonal penicillin (ticarcillin, piperacillin) +/- ß lactamase inhibitor (clavulanate, tazobactam)

Alternative(s): Ceftazidime, cefepime, aztreonam, imipenem, ciprofloxacin

19

Specify which empirical antibiotic should be used for Bacteroides while waiting for culture results

1st line: Metronidazole Alternative(s): Clindamycin

20

Specify which empirical antibiotic should be used for Mycoplasma while waiting for culture results

1st line: Erythromycin, azithromycin

Alternative(s): Doxycycline

21

Specify which empirical antibiotic should be used for Treponema pallidum while waiting for culture results

1st line: Penicillin

Alternative(s): Doxycycline

22

Specify which empirical antibiotic should be used for Chlamydia while waiting for culture results

1st line: Doxycycline, azithromycin

Alternative(s): Erythromycin, ofloxacin

23

Specify which empirical antibiotic should be used for Lyme disease (Borrelia spp.) while waiting for culture results

1st line: Cefuroxime, doxycycline, amoxicillin

Alternative(s): Erythromycin

24

Specify what a Gram stain of Blue/purple color most likely represents.

Gram-positive organism

25

Specify what a Gram stain of Red color most likely represents.

Gram-negative organism

26

Specify what a Gram stain of Gram-positive cocci in chains most likely represents.

Streptococci

27

Specify what a Gram stain of Gram-positive cocci in clusters most likely represents.

Staphylococci

28

Specify what a Gram stain of Gram-positive cocci in pairs (diplococci) most likely represents.

Streptococcus pneumoniae

29

Specify what a Gram stain of Gram-negative coccobacilli (small rods) most likely represents.

Haemophilus sp.

30

Specify what a Gram stain of Gram-negative diplococci most likely represents. 2

Neisseria sp. (sexually transmitted disease, septic arthritis, meningitis)

Moraxella sp. (lungs, sinusitis)

31

Specify what a Gram stain of Plump gram-negative rod with thick capsule (mucoid appearance) most likely represents.

Klebsiella sp.

32

Specify what a Gram stain of Gram-positive rods that form spores most likely represents. 2

Clostridium sp.

Bacillus sp.

33

Specify what a Gram stain of Pseudohyphae most likely represents.

Candida sp.

34

Specify what a Gram stain of Acid-fast organisms most likely represents. 2

Mycobacterium (usually M. tuberculosis)

Nocardia sp.

35

Specify what a Gram stain of Gram-positive with sulfur granules most likely represents.

Actinomyces sp. (PID in patients with IUDs; rare cause of neck mass/cervical adenitis)

36

Specify what a Gram stain of Silver-staining most likely represents.

Pneumocystis jiroveci and cat-scratch disease

37

Specify what a Gram stain of Positive India ink preparation (thick capsule) most likely represents.

Cryptococcus neoformans

38

Specify what a Gram stain of Spirochete most likely represents. 3

Treponema sp., Leptospira sp. (both seen only on dark-field microscopy)

Borrelia sp. (seen on regular light microscope)

39

What is the gold standard for diagnosis of pneumonia?

Sputum culture - obtain the culture before starting antibiotics, although many physicians treat empirically without culture in routine cases.

Obtain blood cultures as well because bacteremia is common with pneumonia.

40

What is the most common cause of pneumonia?

How does it classically present?

Bonus: How should you diagnose + treat this?

Streptococcus pneumoniae.

Presentation: rapid onset of rigors 1-2 days of URI symptoms (sore throat, runny nose, dry cough), followed by fever, pleurisy, and productive cough (yellowish-green or rust-colored from blood)

Diagnose: CXR - lobar consolidation, CBC - elevated WBC with large PMN%

Treatment:

  • macrolide (e.g., azithromycin, clarithromycin)
  • doxycycline
  • third-generation cephalosporin + macrolide or doxycycline
  • fluoroquinolone that provides atypical coverage (e.g., levofloxacin, moxifloxacin).

41

What is the best prevention against S. pneumoniae?

In which patient populations is this most important in?

Vaccination!

Give pneumococcal vaccine to:

  • all children as well as adult patients over 65 years old
  • splenectomized patients
  • patients with sickle-cell disease (who have autosplenectomy) or splenic dysfunction
  • immunocompromised patients (HIV, malignancy, organ transplant)
  • patients with chronic disease (e.g., diabetes, cardiac disease, asthma and other pulmonary disease, renal disease, liver disease, or tobacco use)

42

How do you recognize and treat Haemophilus influenzae pneumonia?

How common is it?

How is it diagnosed and treated?

H. influenzae is now uncommon in children because of vaccination, but is still an important cause
of pneumonia in older adults and in those with underlying lung disease such as COPD

Often it resembles pneumococcal pneumonia clinically, but look for gram-negative coccobacilli on sputum Gram stain.

Treat with amoxicillin or a second- or third-generation cephalosporin.

43

Describe the hallmarks of Staphylococcus aureus pneumonia.

In which patient populations (4) does it tend to affect the most?

S. aureus tends to cause

  • hospital-acquired (nosocomial) pneumonia
  • pneumonia in patients with cystic fibrosis (along with Pseudomonas sp.)
  • patients who abuse IV drugs
  • patients with chronic granulomatous disease (look for recurrent lung abscesses).

Empyema and lung abscesses are relatively common with S. aureus pneumonia.

44

In what clinical situations do you tend to see gram-negative pneumonias? 

Which 3 are the most common?

How should you treat these patients?

  1. Pseudomonas infection is classically associated with cystic fibrosis
  2. Klebsiella infection may be found in patients who are homeless and/or suffer from alcoholism (watch for classic description of currant jelly sputum)
  3. Enteric gram-negative organisms (e.g., Escherichia coli) are associated with aspiration, neutropenia, and hospital-acquired pneumonia.

High mortality rate because often patients are already in poor health and the severity of the pneumonia (abscesses are common).

Treat empirically with an antipseudomonal penicillin (e.g., ticarcillin, piperacillin) +/- beta lactamase inhibitor (e.g., clavulanate, tazobactam).

  • Alternatives include ceftazidime or ciprofloxacin.

45

How do you recognize Mycoplasma pneumonia?

In which patients is it most common?

How is it diagnosed and treated?

cause of atypical pneumonia; most common in adolescents and young adults (the classic patient is a college student or soldier who lives in a dormitory/barracks and has sick contacts)

sx: has a long prodrome with gradual worsening of malaise, headaches, dry, nonproductive cough, and sore throat; the fever tends to be low-grade

dx:

  • CXR: patchy, diffuse bronchopneumonia and classically looks impressive, although the patient often does not feel that bad
  • Positive cold-agglutinin antibody titers, which may cause hemolysis or anemia (compared to chlamydial pneumonia, which has negative cold-agglutinin antibody titers)

Tx:

  • macrolide antibiotic (azithromycin)
  • doxycycline
  • broad-spectrum fluoroquinolone (e.g., levofloxacin, moxifloxacin).

46

How do you recognize chlamydial pneumonia?

In which patients is it most common?

How is it diagnosed and treated?

cause of atypical pneumonia  in adolescents and adults

presents similarly as mycoplasma pneumonia (a long prodrome with gradual worsening of malaise, headaches, dry, nonproductive cough, and sore throat; the fever tends to be low-grade)

dx:

  • CXR: patchy, diffuse bronchopneumonia and classically looks impressive, although the patient often does not feel that bad
  • negative cold-agglutinin antibody titers, which may cause hemolysis or anemia (compared to mycoplasma pneumonia, which has positive cold-agglutinin antibody titers)

Tx:

  • erythromycin in children
  • azithromycin or doxycycline in children > 8 years of age, adolescents, and adults.

47

In which 2 patient populations do you see Pneumocystis jiroveci pneumonia (PCP) and cytomegalovirus (CMV) pneumonia?

How should you diagnose and treat them?

  1. HIV-positive patients with CD4 counts < 200/mm3 (AIDS)
  • CXR: bilateral interstitial lung infiltrates
  • may require bronchoalveolar lavage with silver stain for diagnosis
  • trmt: TMP-SMX + corticosteroids
  1. severely immu- nosuppressed patients (organ transplant recipients on immunosuppressants, patients on cancer chemotherapy)
  • intracellular inclusion bodies
  • trmt: valganciclovir

 

48

What is the best time to treat PCP?

Before it happens.

PCP is acquired when the CD4 count is < 200/mm3. At that point, initiate PCP prophylaxis in an HIV-positive patient with TMP-SMX. Alternatives include dapsone or atovaquone.

49

specify the organism in this scenario: Stuck with thorn or gardening

Bonus: How should you treat this?

Sporothrix schenckii

Treat with itraconazole

50

specify the organism in this scenario: Aplastic crisis in sickle cell disease

Parvovirus B19

51

specify the organism in this scenario: Sepsis after splenectomy  3

Streptococcus pneumoniae

Haemophilus influenzae

Neisseria meningitis

(all encapsulated bacteria)

52

specify the organism in this scenario: Pneumonia in the Southwest (California, Arizona)

Bonus: How should you treat this?

Coccidioides immitis

Treat with itraconazole or fluconazole; amphotericin B for severe disease

53

specify the organism in this scenario: Pneumonia after cave exploring or exposure to bird droppings in Ohio and Mississippi River valleys

Histoplasma capsulatum

54

specify the organism in this scenario: Pneumonia after exposure to a parrot or exotic bird

Chlamydophila psittaci

55

specify the organism in this scenario: Fungus ball/hemoptysis after tuberculosis or cavitary lung disease

Bonus: How should you treat this?

Aspergillus sp.

56

specify the organism in this scenario: Pneumonia in a patient with silicosis

Tuberculosis

57

specify the organism in this scenario: Diarrhea after hiking/drinking from a stream

Bonus: How should you treat this?

Giardia lamblia (look for stool cysts)

treat with metronidazole

58

specify the organism in this scenario: Pregnant woman with cats

Bonus: How should you treat this?

Toxoplasma gondii

Treat infected pregnant women with spiramycin

59

specify the organism in this scenario: B12 deficiency and abdominal symptoms

Diphyllobothrium latum (intestinal tapeworm)

60

specify the organism in this scenario: Seizures with ring-enhancing brain lesion on CT 2

Bonus: How should you treat this?

Taenia solium (cysticercosis) or toxoplasmosis

Treat neurocysticercosis with albendazole or praziquantel, usually with steroids; consider anticonvulsants

61

specify the organism in this scenario: Squamous cell bladder cancer in Middle East or Africa

Schistosoma haematobium

62

specify the organism in this scenario: Worm infection in children (how do they usually present?

Bonus: How should you treat this?

Enterobius sp; Perianal itching, positive tape test

Treat with mebendazole or albendazole

63

specify the organism in this scenario: Fever, muscle pain, eosinophilia, and periorbital edema after eating raw meat

Trichinella spiralis (trichinosis)

64

specify the organism in this scenario: Gastroenteritis in young children

Rotavirus, Norwalk virus

65

specify the organism in this scenario: Food poisoning after eating reheated rice

Bacillus cereus

66

specify the organism in this scenario: Food poisoning after eating raw seafood

Vibrio parahaemolyticus

67

specify the organism in this scenario: Diarrhea after travel to Mexico

Bonus: How should you treat this?

Escherichia coli (Montezuma revenge)

Treat with ciprofloxacin

68

specify the organism in this scenario: Diarrhea after antibiotics

Bonus: How should you treat this?

C. diff

Treat with oral metronidazole or oral vancomycin

69

specify the organism in this scenario: Baby paralyzed after eating honey

Clostridium botulinum (toxin blocks ACh release)

70

specify the organism in this scenario: Genital lesions in children in the absence of sexual abuse or activity

Molluscum contagiosum

71

specify the organism in this scenario: Cellulitis after cat/dog bites

Bonus: how do you treat this?

Pasteurella multocida

Treat with prophylactic amoxicillin-clavulanate

72

specify the organism in this scenario: Slaughterhouse worker with fever

Brucellosis

73

specify the organism in this scenario: Pneumonia after being in hotel or near air conditioner or water tower

Bonus: How should you treat this?

Legionella pneumophila

Treat with azithromycin or levofloxacin

74

specify the organism in this scenario: Burn wound infection with blue/green color

Pseudomonas sp.

75

How is syphilis diagnosed?

What confirmatory tests should you do and why?

Once syphilis is treated, how do the tests readings change?

rapid plasma reagin (RPR) or venereal disease research laboratory (VDRL) test

confirm with: 

  • fluorescent treponemal antibody absorbed (FTA-ABS) or microhemagglutination (MHA-TP) test because false-positive results occur with the RPR and VDRL tests, classically in patients with lupus erythematosus.
  • scrape the base of a genital chancre or condyloma lata and look for spirochetes on dark-field microscopy

Once syphilis is treated, the RPR and VDRL tests become negative, whereas the FTA-ABS and MHA-TP tests often remain positive for life.

 

76

Which group of patients should always be screened for syphilis?

Pregnant women. Early treatment can prevent birth defects.

77

How is syphilis treated?

What should be given to patients who are allergic to the first line treatment?

With penicillin. Use doxycycline for penicillin-allergic patients.

78

Describe the three stages of syphilis.

Primary stage: painless chancre that resolves on its own within 8 weeks

Secondary stage: condyloma lata, maculopapular rash (palms and soles of feet), lymphadenopathy; 6 weeks - 18 months later

Tertiary stage: gummas (granulomas in many organs), neurologic symptoms and signs (neurosyphilis, Argyll-Robertson pupil, dementia, paresis, tabes dorsalis, Charcot joints), thoracic aortic aneurysms.; occurs years after initial infection after a latent phase

79

How do you recognize measles (rubeola) infection in a child?

How are these patients treated?

Look for a lack of immunization, pathognomonic Koplik spots (tiny white spots on buccal mucosa) are seen 3 days after high fever, cough, runny nose, and conjunctivitis +/- photophobia. On the next day, a maculopapular rash begins on the head and neck and spreads downward to cover the trunk (cephalocaudal progression).

Treat supportively.

80

Describe the 3 complications of measles.

  • giant-cell pneumonia, especially in very young and immunocompromised patients
  • otitis media
  • encephalitis, either acute or late (subacute sclerosing panencephalitis, which usually occurs years later).

81

In which patient population is rubella infection (German measles) an important disease?

in pregnant mothers because an infection can cause severe birth defects in the fetus.

Screen all women of reproductive age and immunize those without evidence of rubella antibodies before pregnancy to avoid this complication.

However, the vaccine is contraindicated in pregnant women.

82

How do you recognize a rubella infection in children?

What are the complications?

Rubella is milder than measles.

Signs and symptoms: low-grade fever, malaise, and tender swelling of the suboccipital and postauricular lymph nodes; forchheimer spots on soft palate, arthralgias are common. After a 2- to 3-day prodrome, a faint maculopapular rash appears on the face and neck and spreads to the trunk (cephalocaudal progression, just as in measles)

Complications: encephalitis and otitis media, and either acute or late (subacute sclerosing panencephalitis, which usually occurs years later).

83

How do you recognize roseola infantum (exanthem subitum)?

What causes it?

How common is it?

sx: high temperature (may be ≥ 40°C, 104˚F) with no apparent cause for 4 days, which may result in febrile seizures, followed by an abrupt return to normal temperature just as a diffuse macular/maculopapular rash appears on the chest/abdomen.

Cause: human herpesvirus type 6 

Rare in children > 3 yo

84

How do you recognize erythema infectiosum (fifth disease) in children?

What causes it?

“slapped-cheek” rash accompanied by mild constitutional symptoms (low-grade fever, malaise). One day later, a maculopapular rash appears on the arms, legs, and trunk.

Cause: parvovirus B19, the same virus that causes aplastic crisis in sickle cell disease.

85

How do you recognize chickenpox?

What causes it?

What should you avoid giving to children presenting with chicken pox and why?

discrete macules (usually on the trunk) turn into papules, which turn into vesicles that rupture and crust over; lesions appear in successive crops, the rash will be in different stages of progression in different areas.

cause: varicella virus

avoid: aspirin in a child with a fever unless you have a diagnosis that requires its use because of the risk of Reye syndrome. 

86

How can you make a definitive diagnosis of chickenpox?

At what point is a patient with chickenpox no longer infectious?

A Tzanck smear of tissue from the base of a vesicle shows multinucleated giant cells, but a presumptive diagnosis can be made if the rash is classic.

Infectivity ceases only when the last lesion crusts over.

87

What are the 4 major complications of chickenpox?

  • infection of the lesions with streptococci or staphylococci, which cause erysip- elas, cellulitis, and/or sepsis
  • pneumonia (especially in very young children, adults, and immunocompromised patients)
  • encephalitis
  • shingles (years later; infectious state)

88

Describe the treatment and prophylaxis for chickenpox.

Supportive treatment (acetaminophen, fluids, avoidance of infecting others), but acyclovir can be used in severe cases

Prophylaxis

  • varicella vaccine is recommended for all children in the US
  • varicella zoster immune globulin for patients with debilitating illness (leukemia, AIDS) within 4 days of exposure and for newborns of mothers with chickenpox
  • IVIg can be given if varicella zoster immune globulin is not available

89

What is scarlet fever?

What causes it?

How is it recognized and treated?

What is a sequelae of untreated scarlet fever?

a febrile illness with a rash caused by certain Streptococcus species.

Look for: 

  • history of untreated streptococcal pharyngitis; only streptococcal species that produce erythrogenic toxin can cause scarlet fever
  • Pharyngitis is followed by a sandpaper-like rash on the abdomen and trunk with classic circumoral pallor and strawberry tongue. The rash tends to desquamate once the fever subsides.

Treatment

  • Oral penicillin V is the treatment of choice for streptococcal pharyngitis to prevent rheumatic fever.
  • Alternative therapies: amoxicillin, cephalosporins, macrolides, or clindamycin.

90

What are the diagnostic criteria for Kawasaki disease?

  • Asian Children
  • < 4yo
  • fever for more than 5 days, cervical lymphadenopathy, bilateral conjunctivitis, changes in lip/oral mucosa “strawberry tongue”, desquamating rash
  • also look for arthritis or arthralgias

complication: coronary artery aneurysms (can result in thrombosis -> MI/rupture)

 

91

What is the most feared complication of Kawasaki disease?

How do you prevent it?

What do you need to do for these children long-term?

Complications involve the heart (coronary artery aneurysms, congestive heart failure, arrhythmias, myocarditis, and MI)

Prevent with aspirin + IVIg - both proven to reduce cardiac lesions

Follow with ECHO to detect cardiac involvement

92

Describe the classic findings of Epstein-Barr virus (EBV) infection (infectious mononucleosis).

How do you differentiate it from a streptococcal pharyngitis? 5

Look for: fatigue, fever, pharyngitis, and cervical lymphadenopathy in a young adult.

  • s/sx are similar to those of streptococcal pharyngitis, but malaise tends to be prolonged and pronounced in EBV infection
  • to differentiate from streptococcal pharyngitis, look for the following in EBV
    • Splenomegaly (patients are at increased risk for splenic rupture and should avoid contact sports and heavy lifting).
    • Hepatomegaly.
    • Atypical lymphocytes (bizarre forms that may resemble leukemia) with lymphocytosis, anemia, or thrombocytopenia.
    • Positive serology (heterophile antibodies [Monospot test]) or specific EBV antibodies (viral capsid antigen, Epstein-Barr nuclear antigens).

93

What is an important differential diagnosis of EBV infection?

Acute HIV infection, which can cause a mononucleosis-type syndrome.

94

What is the association between EBV and cancer? 3

EBV is associated with

nasopharyngeal cancer

African Burkitt lymphoma

posttransplant lymphoproliferative disorder.

95

Describe the classic clinical vignette for Rocky Mountain spotted fever.

What causes it? What is the treatment?

Look for

  • history of a tick bite (Rickettsia rickettsii, especially in a patient on the East Coast) 1 week before development of high temperature/chills, severe headache, and prostration or severe malaise.
  • A rash appears 4 days later on the palms/wrists and soles/ankles and spreads rapidly to the trunk and face (unique pattern of spread).
  • Patients often look quite ill (DIC, delirium).

Treat with doxycycline; chloramphenicol is a second choice.

96

How do you recognize and treat the rash of impetigo?

What causes it?

How is it treated?

caused by Streptococcus and Staphylococcus species

look for

  • a history of a break in the skin (previous chickenpox, insect bite, scabies, cut), usually on the face
  • localized rash that starts as thin-walled vesicles that rupture and form yellowish crusts; skin is classically described as “weeping.”
  • The rash is infectious

Trmt: dicloxacillin, cephalexin, or clindamycin to cover both Streptococcus and Staphylococcus species. Topical mupirocin also may be used.

97

Describe the two clinical types of endocarditis.

What are the causative organisms?

Acute (fulminant) endocarditis - typically affects normal heart valves

  • commonly caused by S. aureus.

Subacute endocarditis - insidious onset and typically affects previously damaged or prosthetic valves

  • commonly caused by: Streptococcus viridans, but other streptococcal and staphylococcal species may also be involved (e.g., Staphylococcus epidermis, Streptococcus bovis, enterococci).
  • Suspect colon cancer if S. bovis is found on blood culture.

98

How is endocarditis diagnosed and treated?

dx: blood culture

trmt: empirical treatment is begun before C/S results are known; typical abx used are:

  • for native valve:
    • antistaphylococcal penicillin (e.g., oxacillin, nafcillin) + aminoglycoside  
    • third-generation penicillin or cephalosporin + aminoglycoside
  • for prosthetic valve:
    • vancomycin plus gentamicin + cefepime or a carbapenem.

99

What are the classic signs and symptoms of endocarditis?

  • general signs of infection (e.g., fever, tachycardia, malaise)
  • new-onset heart murmur
  • embolic phenomena (stroke and other infarcts)
  • Osler nodes (painful nodules on tips of fingers)
  • Janeway lesions (nontender, erythematous lesions on palms and soles)
  • Roth spots (round retinal hemorrhages with white centers)
  • septic shock (more likely with acute than subacute disease)

100

What elements of the history point to endocarditis? 3

Look for patients who are more likely to be affected by endocarditis:

  • IVDU - usually have right-sided lesions, although left-sided lesions are much more common in the general population.
  • Patients with abnormal heart valves (prosthetic valves, rheumatic valvular disease, congenital heart defects such as ventricular septal defects or tetralogy of Fallot).
  • Postoperative patients (especially after dental surgery).

101

What are the recommendations for endocarditis prophylaxis?

antibiotic prophylaxis for DENTAL procedures, esp. if patient has a history of

  • prosthetic cardiac valve
  • previous infectious endocarditis
  • congenital heart disease
  • cardiac transplant recipients who develop valvulopathy

Note: antibiotic prophylaxis is no longer recommended for GU or GI procedures.

Prophylaxis:

  • single dose Amoxicillin
  • Cephalexin, clindamycin, azithromycin, or clarithromycin may be used in patients with penicillin allergy.
  • Ampicillin, cefazolin, ceftriaxone, or clindamycin may be used for patients unable to take oral medication.

102

What is the classic age group for meningitis?

Describe the physical findings.

Neonates are the classic age group for meningitis; 75% of all cases occur in children younger than 2 years.

Sx: lethargy, hyperthermia or hypothermia, poor muscle tone, bulging fontanelle, vomiting, photophobia, AMS, and signs of generalized sepsis (hypotension, jaundice, respiratory distress), seizures

103

What should you do if you suspect meningitis?

do a lumbar puncture immediately

begin broad-spectrum antibiotics and intravenous fluids 

Do not wait for culture or other results before starting antibiotics.

104

What is the most common neurologic sequela of meningitis?

What are some other sequelae that may result?

Hearing loss

Other: mental retardation, motor deficits/paresis, epilepsy, and learning/behavioral disorders.

105

What are the 4 common viral (aseptic) causes of meningitis in children and in what scenarios do they normally present in?

What is the best way to prevent this?

Treatment?

  • Mumps and measles meningitis may be seen in children who are unimmunized.
  • Watch for neonatal herpes encephalitis (HSV-2) if the mother has genital lesions of herpes simplex virus at the time of delivery
  • Other children and adults can develop HSV-1 herpes encephalitis, which classically affects the temporal lobes on a head CT or MRI.

The best treatment is prevention via immunization.

Give intravenous acyclovir.

106

Which 2 types of bacterial meningitis require antibiotic prophylaxis in contacts?

What prophylaxis is normally given in both cases?

N. meningitidis and H. influenzae.

if Neisseria sp., give all contacts rifampin, ciprofloxacin, ceftriaxone, or azithromycin

If H. influenza, give all contacts rifampin.

107

What are the “big three” respiratory infections in patients younger than 5 years old?

What are they commmonly caused by?

Croup (parainfluenza, influenza)

epiglottitis (H. influenza type B)

bronchiolitis (RSV)

108

How do you recognize croup (acute laryngotracheitis)?

Describe the cause and treatment.

parainfluenza virus (75% of cases); influenza virus

Look for

  • a child 1 to 2 years of age.
  • usually occurs in the fall or winter
  • begins with symptoms of viral URI (rhinorrhea, cough, fever);1 to 2 days later patients develop a “barking” cough, hoarseness, and inspiratory stridor
  • “steeple sign” (subglottic narrowing of the trachea) on chest/neck xray

Treat with dexamethasone, racemic epinephrine, a mist tent, and humidified oxygen.

109

How do you recognize epiglottitis?

Describe the cause and treatment.

What should you avoid doing in these children and what is the rationale behind it?

H. influenzae type b (most common),  S. aureus, S. pyogenes, and S. pneumoniae

Look for:

  • children 2 to 5 years old that were not vaccinated against H. influenza
  • little or no prodrome with rapid progression to high temperature, toxic appearance, drooling, and respiratory distress with no coughing.
  • The thumb sign (swollen, enlarged epiglottis) on lateral neck xray

Treatment

  • Do not examine the throat or irritate the child in any way. You may precipitate airway obstruction.
  • be prepared to establish an airway (intubation and, if needed, tracheostomy).
  • treat with oxacillin or cefazolin or clindamycin or vancomycin plus cefotaxime or ceftriaxone.

110

Describe the classic clinical vignette for bronchiolitis.

What is the cause? How is it treated?

RSV (75% of cases), parainfluenza, influenza (25% of cases)

Look for:

  • children aged 0 to 18 months
  • usually occurs in the fall/winter
  • first develop symptoms of viral URI (rhinorrhea, cough, fever), followed 1 to 2 days later by rapid respirations, intercostal retractions, and expiratory wheezing
  • The child may have crackles on auscultation of the chest.
  • Diffuse hyperinflation of the lungs with flattened diaphragms on CXR

Trmt:

  • supportive (oxygen, mist tent, bronchodilators, IV fluids).
  • Ribavirin only in patients with severe symptoms or who are at high risk (e.g., patients with cyanosis or other chronic health problems).

111

What “old-school” pediatric infection causes pseudomembranes and myocarditis? What about whooping cough?

What are the common reasons why these two show up in the general population?

How are these two treated?

Diphtheria (Corynebacterium diphtheriae)

  • Pseudomembranes pharynx, tonsils, and uvula and myocarditis 
  • Treat diphtheria with antitoxin and either penicillin or erythromycin.

pertussis (Bordetella pertussis) 

  • Paroxysmal cough + whooping inspiratory noise
  • Treat with azithromycin or erythromycin

Common in children who are unimmunized (ie child of immigrants)

112

In what clinical scenario does rabies occur in the United States?

How long is the incubation period? 

Describe the classic physical findings.

bites from infected animals, such as bats, skunks, raccoons, or foxes; rabies as a result of bites from dogs is rare because of vaccination.

incubation period: 1 to 2 months.

classic findings: hydrophobia (fear of water as a result of painful swallowing) and CNS signs (paralysis).

113

What should you do after a patient is bitten by an animal?

  1. Cleanse the wound thoroughly with soap and give amoxicillin-clavulanate for cellulitis prophylaxis
  2. Observe the animal. If possible, capture and observe the dog or cat to see if it develops rabies. If a wild animal is caught, it should be killed and the brain tissue examined for rabies.
  3. If the wild animal escapes or has rabies, give rabies immunoglobulin and rabies vaccine.
  4. In cases of a dog or cat bite, do not give immunoglobulin or vaccine unless the animal acted strangely or bit the patient without provocation and rabies is prevalent in the area (rare).
  5. Do not give prophylaxis or vaccine for rabbit or small rodent bites (e.g., rats, mice, squirrels, chipmunks).

114

What are the two main infections caused by S. pyogenes (group A streptococci)?

What are the 3 common sequelae? 

pharyngitis and erysipelas

Sequelae include rheumatic fever, scarlet fever, and poststreptococcal glomerulonephritis.

115

How does streptococcal pharyngitis present?

How do you diagnose and treat it?

Look for

  • sore throat
  • fever
  • tonsillar exudate
  • enlarged tender cervical nodes
  • leukocytosis

Dx:

  • (+) streptococcal throat culture
  • Elevated titers of antistreptolysin O (ASO) and anti-DNase antibody for a retrospective diagnosis in patients with rheumatic fever or poststreptococcal glomerulonephritis.

Trmt: penicillin, amoxicillin, cephalosporin, macrolide, or clindamycin to avoid rheumatic fever and scarlet fever.

116

What are the major and minor Jones criteria for rheumatic fever?

What is required to make the diagnosis?

Why is rheumatic fever less common today?

What should you give all patients affected by rheumatic fever endocarditis?

major: migratory polyarthritis, carditis, subcutaneous nodules, erythema marginatum, and chorea

minor: elevations in ESR, CRP, WBC, and ASO titer; prolonged PR interval on ECG; and arthralgia.

The diagnosis of rheumatic fever requires:

  • a history of streptococcal infection AND
  • the presence of two major criteria OR one major + two minor criteria.

Treatment of streptococcal pharyngitis with antibiotics markedly reduces the incidence of rheumatic fever; thus it is less common today.

Give all patients affected by rheumatic fever endocarditis antibiotic prophylaxis before surgical procedures, especially dental procedures

117

How do you recognize poststreptococcal glomerulonephritis?

How do they usually present?

How is it treated?

Does treatment of streptococcal infection reduce the incidence of poststreptococcal glomerulonephritis?

occurs commonly after streptococcal skin infection, but also after pharyngitis

Look for

  • children with a history of infection with a nephritogenic strain of Streptococcus species 1 to 3 weeks earlier
  • an abrupt onset of hematuria, proteinuria (mild, not in nephrotic range), RBC casts, hypertension, edema (especially periorbital), and elevated BUN/Cr.

Treat supportively. Control BP and use diuretics for severe edema.

Treatment of streptococcal infections does not reduce the incidence of poststreptococcal glomerulonephritis.

118

Distinguish between impetigo and erysipelas - how are they the same? different?

How should they be treated?

Superficial skin infections caused by Strep or S. aureus and often occur after a break in the skin (e.g., trauma, scabies, insect bite).

Impetigo

  • classically changes first from maculopapules to vesicopustules and bullae and then to honey-colored, crusted lesions.
  • contagious!
  • Staphylococci are a more frequent cause than streptococci
    • think of staphylococci if a furuncle or carbuncle is present
    • think of streptococci if glomerulonephritis develops
  • trmt: dicloxacillin, cephalexin, or clindamycin

Erysipelas

  • superficial cellulitis that appears red, shiny, and swollen
  • tender
  • be associated with vesicles and bullae, fever, and lymphadenopathy
  • trmt: penicillin or amoxicillin, may require parenteral therapy with cephalosporin (ceftriaxone or cefazolin) if systemic symptoms such as fever and chills are present

119

What organisms typically cause cellulitis?

What special circumstances should make you think of atypical causes?

  • Streptococci and staphylococci cause most cases
  • Pseudomonas with burns or severe trauma
  • Pasteurella multocida after dog or cat bites (treat with ampicillin)
  • Vibrio vulnificus in fishermen or other patients exposed to salt water (treat with tetracycline).
  • Diabetic patients with foot ulcers tend to have polymicrobial infections and need powerful, broad-spectrum antibiotic coverage.

120

Describe the physical findings of cellulitis.

How does it differ than that of erysipelas?

How do you treat cellulitis?

 

Both manifest as areas of skin erythema, edema, warmth, and tenderness, BUT

  • Erysipelas involves the upper dermis and superficial lymphatics
  • Cellulitis involves the deeper dermis and subcutaneous fat.
    • Antibiotic selection depends on whether the cellulitis is purulent or nonpurulent.

      • purulent (think s. aureus) -> give TMP-SMX, doxycycline, clindamycin, linezolid
      • non-purulent -> give dicloxacillin, cephalexin, and clindamycin

121

Define necrotizing fasciitis.

How is it treated?

infection of the deeper layers of skin and subcutaneous tissues, spreads across fascial planes within the subcutaneous tissue

progression of cellulitis to necrosis and gangrene quickly, with signs of crepitus and signs of systemic toxicity (e.g., tachycardia, fever, hypotension) evident

Trmt: IV fluids, surgical debridement, and broad-spectrum antibiotics (carbapenem (imipenem or meropenem) + clindamycin)

122

What is endometritis (puerperal fever)?

What is the most common cause?

How do you recognize and treat it?

infection of the endometrial lining; cause of postpartum fever

look for: uterine tenderness

most common cause: Streptococcus spp.

treat: clindamycin + gentamicin after local cultures are obtained.

123

What infection in neonates is caused by Streptococcus agalactiae (group B streptococci)?

How is it acquired?

How is it treated?

neonatal meningitis or sepsis

the organism is often part of normal vaginal flora and may be acquired as the baby passes through the birth canal

treatment: Expectant mothers are cultured for group B strep, and if it is present around the time of delivery, then prophylactic IV penicillin (preferred) or IV ampicillin is given to the mother to prevent meningitis in the newborn

124

Other than pneumonia, what infections does S. pneumoniae commonly cause?

Otitis media

meningitis

sinusitis

spontaneous bacterial peritonitis

125

What are the main infections caused by S. aureus?

  • Pneumonia (often forms lung abscess or empyema)
  • Endocarditis (especially IVDU)
  • Osteomyelitis (the most common cause unless sickle cell disease is present)
  • Septic arthritis
  • Food poisoning (via a preformed toxin)
  • Toxic shock syndrome (via a preformed toxin)
  • Skin
    • Furuncles and carbuncles
    • Scalded skin syndrome (via a preformed toxin; affects younger children who often present with impetigo, then desquamate)
    • Impetigo
    • Cellulitis
    • Wound infections
    • Skin and soft-tissue abscesses (especially after breast feeding or after a furuncle)

126

What is the treatment of choice for staphylococcal infections?

antistaphylococcal penicillin (e.g., methicillin, dicloxacillin)

Use vancomycin, clindamycin, doxycycline, TMP-SMX, linezolid if the staphylococcal species is or suspected to be MRSA

Most abscesses must be treated first with surgical I&D because antibiotics cannot penetrate through the walls of an abscess cavity.

127

describe the preferred treatment for tuberculosis if the clinical scenario was an
exposed adult with negative PPD skin test

none

128

describe the preferred treatment for tuberculosis if the clinical scenario was an
exposed child younger than 5 years old with negative PPD

INH (isoniazid) for 3 months, then repeat PPD

129

describe the preferred treatment for tuberculosis if the clinical scenario was an
prophylaxis for PPD conversion (negative to positive), no active disease

INH (isoniazid) for 9 months

130

describe the preferred treatment for tuberculosis if the clinical scenario was
an active pulmonary disease/positive culture

INH/rifampin/pyrazinamide/ethambutol for 2 months, then INH/rifampin for 4 months in most patients

131

Name 4 important tuberculosis treatment issues.

  • Multidrug resistant strains - an increasing problem; require 4-drug therapy (pyrazinamide, isoniazid, ethambutol, and rifampin)
  • Noncompliance with medicationsdirectly observed therapy (someone watches the patient take medications every day) is recommended.
  • B6 deficiency - supplementation with vitamin B6 (pyridoxine) for patients on isoniazid (INH), or watch for neuropathy, confusion, angular chilitis, or a seborrheic dermatitis-like rash.
  • Liver dysfunction in patients on therapy - advise patients to abstain from alcohol while on treatment and should have their transaminase levels monitored