Chapter 5 - Infection++ Flashcards

2
Q

What is the most common immune deficiency?

A

Malnutrition

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3
Q

What is the microflora of the stomach?

A

Virtually sterile; some GPCs, some yeast

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4
Q

What is the microflora of the proximal small bowel?

A

10^5 bacteria, mostly GPCs

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5
Q

What is the microflora of the distal small bowel?

A

10^7 bacteria, GPCs, GPRs, GNRs

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6
Q

What is the microflora of the colon?

A

10^11 bacteria, almost all anaerobes, some GNRs, GPCs

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7
Q

What is the most common organism in the GI tract?

A

Anaerobes - Bacteroides

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8
Q

What is the most common aerobic bacteria in the colon?

A

E. coli

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9
Q

What is the most common bacterial cause of gram-negative sepsis?

A

E. coli

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10
Q

What type of toxin is released by E. coli, what are its effects?

A

Endotoxin (lipopolysaccharide lipid A); triggers the release of TNF-alpha from macrophages, activates complement and coagulation cascade

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11
Q

What is the optimal glucose level in a septic patient?

A

100-120 mg/dL

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12
Q

What is the dx and tx of C. diff colitis?

A

Dx: fecal leukocytes in stool, C. diff toxin; Tx: oral vanco or flagyl, IV flagyl, lactobacillus

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13
Q

What percentage of abdominal abscesses have anaerobes?

A

90%

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14
Q

What percentage of abdominal abscesses have both anaerobic and aerobic bacteria?

A

80%

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15
Q

How many days post-op do abdominal abscesses occur?

A

7-10d

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16
Q

What are indications (associated diagnosis, exam findings) for antibiotics in patients with abdominal abscesses?

A
  • DM, cellulitis, clinical signs of sepsis
  • Fever, elevated WBC
  • Bioprosthetic hardware
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17
Q

Wound infections develop in what percentage of clean (hernia) cases?

A

class I - 1-4%

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18
Q

Wound infections develop in what percentage of clean contaminated cases (elective colon resection w/ prepped bowel)?

A

class II - 6-9%

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19
Q

Wound infections develop in what percentage of contaminated cases (GSW to colon w/ repair)?

A

class III - 13-20%

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20
Q

Wound infections develop in what percentage of grossly contaminated cases (stool in peritoneum)?

A

class IV - 40%

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21
Q

What is the most common organism overall in surgical wound infections?

A

Staph aureus (coagulase positive)

Central lines and prosthetic grafts have more Staph epi

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22
Q

What is exoslime?

A

Exopolysaccharide matrix released by staph species

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23
Q

What is the most common GNR in surgical wound infections?

A

E. coli

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24
Q

What is the most common anaerobe in surgical wound infections?

A

B. fragilis; presence indicates necrosis or abscess, implies translocation from gut

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25
Q

How many bacteria are needed to create a wound infection?

A

>10^5, less needed if foreign body present

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26
Q

What are the surgical and patient associated risk factors for perioperative wound infections?

A
  • Surgical: long operations, hematoma/seroma formation
  • Patient: advanced age, chronic disease (COPD, renal/liver failure, DM), malnutrition, immunosuppressive drugs
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27
Q

What is the most common nonsurgical infection

A

UTI (most commonly E. coli), urinary catheters the biggest risk factor

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28
Q

What is the leading cause of infectious death after surgery?

A

Nosocomial pneumonia

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29
Q

What are the most common organisms in ICU pneumonia?

A

1 S. aureus, #2 Psuedomonas

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30
Q

What is the most common class of organisms in ICU pneumonia?

A

GNR - oropharynx gets overgrown by enteric organisms then get aspirated

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31
Q

What are the most common organisms in line infections?

A

1 S. epidermidis (coag neg staph), #2 S. aureus, #3 yeast

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32
Q

What is the line salvage rate with antibiotics?

A

50%, less with yeast infections

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33
Q

Which organisms are found in necrotizing soft tissue infectons?

A

Beta-hemolytic Strep (group A), C. perfringens, mixed organisms

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34
Q

Organisms found in necrotizing fasciitis?

A

Beta-hemolytic Strep (group A), can be polymicrobial

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35
Q

What are the signs of necrotizing fasciitis?

A

Overlying skin pale red, progress to purple with blisters; thin, gray, foul-smelling drainage, crepitus

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36
Q

What is the treatment of necrotizing fasciitis?

A

Early debridement, high-dose penicillins, broad spectrum if thought to be polyorganismal

Clindamycin added for anti-toxin effects

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37
Q

How does necrotic tissue set up an environment for C. perfringens infections?

A

Decreases oxidation-redux potential

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38
Q

C. perfringens has what type of toxin?

A

alpha toxin

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39
Q

What will a gram stain show with C. perfringens infection?

A

GPRs without WBCs

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40
Q

What organisms are found in Fournier’s gangrene?

A

Mixed organisms (GPCs, GNRs, anaerobes)

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41
Q

When do you cover for fungal infection?

A

Positive blood cultures, 2 sites other than blood, 1 site with severe symptoms, endophthalmitis, pts on prolonged bacterial abx without improvement

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42
Q

Description of abscess caused by Actinomyces (not a true fungus)? Locations? Most common organ system with symptoms?

A

Tortuous abscesses in cervical, thoracic, abdominal areas; most commonly with pulmonary symptoms

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43
Q

Treatment for Actinomyces?

A

Drainage and penicillin G

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44
Q

Organ systems affected by Nocardia (not a true fungus)?

A

Pulmonary and CNS

45
Q

Treatment for Nocardia?

A

Drainage and sulfonamides (bactrim)

46
Q

Organ system affected by Histoplasmosis? What geographical regions are associated with infection?

A

Pulmonary most common; Mississippi and Ohio River valleys

47
Q

Treatment for Histoplasmosis?

A

Can watch if no symptoms. Amphotericin for severe infections

48
Q

Organ system affected most with Cryptococcus?

A

CNS most common

49
Q

Treatment for Cryptococcus?

A

Amphotericin for severe infections

50
Q

Symptoms with Coccidioidomycosis?

A

Pulmonary; Southwest

51
Q

Treatment for Coccidioidomycosis?

A

Amphotericin for severe infections

52
Q

Spontaneous (primary) bacterial peritonitis is secondary to what?

A

Decreased host defenses (intrahepatic shunting, impaired bactericidal activity in ascities); NOT due to transmucosal migration

53
Q

SBP is caused by which organisms?

A

Monobacterial: 50% E. coli, 30% Strep, 10% Klebsiella

54
Q

What is diagnostic of SBP on paracentesis?

A

PMNs > 250 cells/cc, cultures positive, no other causes

55
Q

Treatment for SBP?

A

Ceftriaxone or other 3rd generation cephalosporin

56
Q

What is used for short term prophylaxis against SBP?

A

Fluoroquinolones (cipro)

57
Q

What causes secondary bacterial peritonitis?

A

Intra-abdominal source (transmucosal migration, perforated viscus); polymicrobial, B. fragilis, E. coli, Enterococcus

58
Q

Treatment for secondary bacterial peritonitis?

A

Broad spec abx and often laparotomy

59
Q

Chance of contracting HIV with HIV+ blood transfusion?

A

70%

60
Q

Chance of infant contracting HIV from positive mother?

A

30%

61
Q

Chance of contracting HIV from needle stick?

A

0.3%

62
Q

Chance of contracting HIV from mucous membrane exposure?

A

1%

63
Q

What is the most common cause for laparotomy in HIV patients?

A

Opportunistic infections (CMV most common)

64
Q

What is the most common intestinal manifestation of AIDS?

A

CMV colitis (pain, bleeding or perforation)

65
Q

Most common organ affected by lymphoma in HIV patients?

A

Stomach, followed by rectum (mostly Non-Hodgkin’s, 70% B cell)

66
Q

What causes GI bleeds in HIV patients?

A

Upper: Kaposi’s sarcoma; Lower: CMV, bacterial, HSV (lower more common)

67
Q

What are the CD4 counts in normal, symptomatic disease, and opportunistic infections?

A

Normal: 800-1200; Symptomatic disease: 300-400; Opportunistic infections: 200

*Keep cutting in half: 800 to 400 to 200

68
Q

Chronic infection occurs in what % of Hep C patients?

A

60%

69
Q

Cirrhosis occurs in what % of Hep C patients?

A

15% over 20y

70
Q

HCC occurs in what % of Hep C patients?

A

1-5%

71
Q

Treatment of brown recluse spider bites?

A

Dapsone; may need resection of area/skin graft for large ulcers

72
Q

What organisms cause acute septic arthritis?

A

staph A, strep, N gonorrhea

73
Q

Treatment of acute septic arthritis?

A

Drainage, 3rd-gen cephalosporins and vanco

74
Q

What organisms cause diabetic foot infections?

A

Mixed staph, strep, GNRs, anaerobes

75
Q

Treatment of diabetic foot infections?

A

Broad spectrum abx: Unasyn, Zosyn

76
Q

What organism is found in human bites?

A

Eikenella, can cause pernament joint inujury

77
Q

What organism is found in dog/cat bites?

A

Pasturella multocida

78
Q

Treatment for human/dog/cat bites?

A

Broad-spectrum abx: Augmentin

79
Q

Most common organisms for impetigo, erysipelas, cellulitis, folliculitis?

A

Staph and strep

80
Q

Most common organisms in PD cath infections?

A

S. aureus, S. epidermidis

81
Q

Treatment of PD cath infections?

A

Intraperitoneal vanco/gent; removal of catheter for peritonitis that lasts for 4-5d

82
Q

Risk factors for sinusitis?

A

Nasoenteric tubes, intubations, facial fractures

83
Q

If a high fever (102) occurs within 48 hrs postop, what are three diagnostic considerations?

A
  • atelectasis - dec breath sounds, dec O2; CXR
  • viscous injury/leak - review op note, peritonitis; OR
  • invasive wound infection - B-hemolytic strep, clostridia; OR
84
Q

What is included in the ventilator bundle to prevent VAP?

A
  • HOB elevation
  • sedation vacation
  • assess readiness for extubation
  • PUD ppx
  • DVT ppx
  • daily chlorhexidine care
85
Q

What modifications were added to the ventilator bundle for non-intubated postop patients to prevent HAP?

A
  • IS
  • mobilization
  • chlorhexidine mouth care
86
Q

In febrile ICU patients with nasogastric or nasotracheal tubes, especially with facial fractures, what diagnosis needs to be considered?

A
  • paranasal sinusitis
  • if suspicious, get CT - air-fluid levels, mucosa thick
  • dx: sinus aspirate - WBC, bacteria
  • of note, can have concurrent otitis media
  • tx: irrigation, decongestion, abx (like HAP)
87
Q

What are four controllable perioperative factors that can prevent SSI?

A
  • sterile technique
  • appropriate ppx abx
  • temperature
  • glucose
88
Q

In surgical wounds away from the perineum and without bowel entry, what are the likely pathogens?

A
  • S aureus
  • streptococci
  • tx with ancef 1g q8h
  • risk of MRSA: vancomycin
89
Q

In surgical wounds near the perineum or with associated bowel entry, what is characteristic of a culture?

A
  • mixed aerobic and anaerobic bacteria
  • tx with cefoxitin 1g q6h
  • if infection severe, broaden coverage - imipenem, meropenem, zosyn
90
Q

In a patient who is systemically with a pleural effusion and no other source of infection, what test should be done?

A

thoracentesis - gram stain and culture

91
Q

In a patient s/p esophagectomy who presents with empyema, what pathology should be ruled out?

A
  • leak
  • get swallow study, CT, endoscopy
  • consider stent
92
Q

In a patient who has undergone a pneumonectomy who presents with a fistula, what pathology must be ruled out?

A
  • bronchopleural fistula
  • imaging can be nonspecific, often need bronchoscopy
  • often need reoperation with closure including a pedicle tissue flap buttress
93
Q

In an immunocompromised patient, what further antibiotic should be considered in a patient w/ empyema s/p esophageal or pulmonary surgery?

A

antifungal

94
Q

Retained hemothorax in trauma can cause empyema, what imaging study is superior?

A

CT

95
Q

If a patient with hemothorax s/p tube has persistent collection or output greater than 10 ml/kg, what is the next step in management?

A

second tube

early VATS can prevent empyema

96
Q

How is superficial sternal wound infection diagnosed?

A
  • clinically
  • purulent drainage, redness, fever, tenderness
97
Q

What is the hallmark of deep sternal wound infection?

A
  • instability or palpable clicking
  • suspect mediastinitis with systemic signs
  • CT used to determine if mediastinitis is present
98
Q

How are sternal infections treated?

A

OR with debridement and flap

99
Q

In a patient s/p cranial trauma or intracranial instrumentation who has neck stiffness, AMS, and systemic illness, what diagnostic study should be performed?

A

dx: suspect meningitis
workup: diagnostic lumbar puncture, start abx, await cx results

100
Q

All open fractures should receive what to prevent OM?

A
  • abx ppx
  • cover gram positives (S aureus)
  • some need gram negative ppx (P aeruginosa)
101
Q

What are the requirements to diagnose CLABSI?

A
  • one of the following:
  • non-contaminant pathogen isolated in 1/2 cx not related to other sites of infection
  • >1 positive cx of skin contaminant on separate occasions with signs of systemic illness
102
Q

What is the decision-making point in workup of long-term catheter infections?

A
  • determine if exit-site vs tunnel - abx vs removal
  • exit site - signs within 2 cm around the exit site
103
Q

For locally infected central line catheters (w/o changes in vitals or labs), what can be considered adequate treatment?

A

removal of the catheter; monitor for improvement - if afebrile without leukocytosis in 24 hrs, no abx needed

104
Q

In a patient who needs central access with an infected catheter, what should be done to get access?

A

place a line at a separate site, don’t just exchange the line

105
Q

When can a line exchange be done?

A

In a patient with systemic signs of illness without a source and without local signs of line infection, the line can be exchanged for a new one and sent for semiquantitative culture.

106
Q

Most common pathogens in intra-abdominal infections.

A
  • E. coli, Bacteroides, and Streptococcus
  • gram-positive, gram-negative and anaerobes