Chapter 5: Infection Flashcards

1
Q

MC cause of immune deficiency.

A

Malnutrition

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2
Q

Microflora: stomach

A

Virtually sterile.
Some GPCs.
Some yeast.

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3
Q

Microflora: proximal small bowel

A

10^5 bacteria.

Mostly GPCs.

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4
Q

Microflora: distal small bowel

A

10^7 bacteria.

GPCs, GPRs, GNRs.

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5
Q

Microflora: Colon

A

10^11 bacteria.

Almost all anaerobes, some GNRs, GPCs.

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6
Q

MC anaerobe in the colon

A

Bacteroides fragilis

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7
Q

MC aerobic bacteria in the colon

A

Escherichia coli

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8
Q

MC source of fever within 48 hours

A

atelectasis

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9
Q

MC fever source 48 hours - 5 days

A

urinary tract infection

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10
Q

MC fever source after 5 days

A

wound infection

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11
Q

MCC gram negative sepsis

A

E coli

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12
Q

mechanism of gram negative sepsis

A

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

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13
Q

Insulin / glucose: early vs late gram negative sepsis

A

Early: decreased insulin, increased glucose (impaired utilization)
Late: increased insulin, increased glucose secondary to insulin resistance

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14
Q

Often occurs just before the patient becomes clinically septic

A

Hyperglycemia

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15
Q

Optimal glucose level in a septic patient

A

100 - 200 mg/dL

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16
Q

Clostridium difficile colitis
Dx: ?
Tx: ?

A

Dx: C difficile toxin
Tx:
Oral - vancomycin or flagyl
IV - Flagyl; lactobacillus can also help.

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17
Q

Infection: % Clean (hernia)

A

2%

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18
Q

Infection: % Clean contaminated (elective colon resection with prepped bowel)

A

3 - 5%

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19
Q

Infection: % Contaminated (GSW to colon with repair)

A

5 - 10%

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20
Q

Infection: % Gross contamination (abscess)

A

30%

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21
Q

Purpose of prophylactic antibiotics

- Dosing?

A

To prevent surgical site infections

- Stop within 24 hours of end operation time, except cardiac, which is stopped within 48 hours of end operation time.

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22
Q
  • Coagulase positive

- MC organism overall in surgical wound infections

A

Staphylococcus aureus

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23
Q

Coagulase negative organism

A

Staphylococcus epidermidis

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24
Q

MC anaerobe in surgical wound infections

A

B. fragilis

  • Recovery from tissue indicates necrosis or abscess (only grows in low redox state)
  • Also implies translocation from the gut
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25
Q

How many bacteria are needed for wound infection?

A

> 10^5 bacteria.

- Less bacteria is needed if foreign body is present

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26
Q

Risk factors for wound infection

A

Long operations. Hematoma or serum formation. Advanced age. Chronic disease (e.g., COPD, renal failure, liver failure, DM), malnutrition, immunosuppressive drugs.

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27
Q

Surgical infections within 48 hours of procedure

A
  • Injury to bowel with leak
  • Invasive soft tissue infection - Clostridium perfringens and beta-hemolytic strep can present within hours postoperatively (produce exotoxins)
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28
Q

MC infection in surgery patients

A

UTI

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29
Q

Leading cause of infectious death after surgery

A

Nosocomial pneumonia

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30
Q

What is nosocomial pneumonia related to?

A

Length of ventilation; aspiration from duodenum thought to have a role.

31
Q

MC organisms in ICU pneumonia

A
#1 S aureus
#2 Pseudomonas
32
Q

1 class of organisms in ICU pneumonia

A

GNRs

33
Q

MCC line infections

A
#1. S epidermidis
#2. S. aureus
#3. Yeast
34
Q

% Line salvage rate with infection

A

50% line salvage rate with antibiotics; much less likely with yeast line infections.

35
Q

Necrotizing soft tissue infections

A
  • Beta-hemolytic Strep (group A), C perfringens, or mixed organisms
  • Usually occur in patients who are immunocompromised (DM) or who have poor blood supply.
  • Can present very quickly after surgical procedures (within hours)
36
Q

Necrotizing fasciitis

A
  • Usually beta-hemolytic GAS
  • Overlying skin may be pale red and progress to purple with blister or bullae development.
  • Overlying skin can look normal in the early stages.
  • Thin, gray, foul-smelling drainage; crepitus.
  • Tx: early debridement, high-dose penicillin, may want broad spectrum if thought to be polyorganismal
37
Q

C. perfringens infections

A
  • Pain out of proportion to exam, may not show signs with deep infection.
  • Gram stain shows GPRs without WBCs
  • Myonecrosis and gas gangrene (common presentation)
  • Can occur with farming injuries
  • Tx: early debridement, high dose penicillin
38
Q

Pathophysiology C. perfringens infection

A

Necrotic tissue decreases oxidation-redux potential, setting up environment for C. perfringens.

39
Q

C. perfringens: toxin.

A

Alpha toxin

40
Q

Actinomyces

A
  • Pulmonary symptoms most common; can cause tortuous abscesses in cervical, thoracic, and abdominal areas
    Tx: drainage and penicillin G
41
Q

Nocardia

A
  • Not a true fungus
  • Pulmonary and CNS symptoms most common
    Tx: drainage and sulfonamides (Bactrim)
42
Q

Candida

A

Fungus: common inhabitant of the respiratory tract.
Tx: fluconazole (some Candida resistant), anidulafungin for severe infections

43
Q

Aspergillosis

A

Voriconazole for severe infections

44
Q

Histoplasmosis

A

Pulmonary symptoms usual
Mississippi and Ohio River Valleys
Tx: Liposomal amphotericin for severe infections

45
Q

Cryptococcus

A

CNS symptoms most common; usually in AIDS patients.

Tx: Liposomal amphotericin for severe infections.

46
Q

Coccidioidomycosis

A

Pulmonary symptoms
Southwest
Tx: liposomal amphotericin for severe infections

47
Q

Risk factor for spontaneous bacterial peritonitis

A

Low protein

48
Q

Organisms in primary SBP

A

Monobacterial

  • 50% E. coli
  • 30% Streptococcus
  • 10% Klebsiella
49
Q

Pathophysiology of spontaneous bacterial peritonitis

A

Secondary to decreased host defenses (intrahepatic shunting, impaired bactericidal activity in ascites); not due to transmucosal migration

50
Q

Cultures in spontaneous bacterial peritonitis

A

Fluid cultures are negative in many cases

51
Q

Dx: spontaneous bacterial peritonitis

A

PMNs > 500 cells/cc diagnostic

52
Q

spontaneous bacterial peritonitis: treatment, prophylaxis

A

Tx: Ceftriaxone or other 3rd generative cephalosporin
Prophylaxis: fluoroquinolonges good (norfloxacin)

53
Q

What do you need to r/o in primary spontaneous bacterial peritonitis?

A

Intra-abdominal source (eg, bowel perforation) if not getting better on antibiotics or if cultures are polymicrobial
- Liver transplant not an option with active infection

54
Q

Secondary bacterial peritonitis

A
  • Intra-abdominal source (implies perforated viscus)
  • Polymicrobial (B fragilis, E coli Enterococcus MC organisms)
    Tx: Usually need laparotomy to find source
55
Q

Exposure risk: HIV blood transfusion

A

70%

56
Q

Exposure risk: infant from positive mother with HIV

A

30%

57
Q

Exposure risk: Needle stick form HIV positive patient

A

0.3%

58
Q

Exposure risk: HIV positive Mucous membrane exposure

A

0.1 %

59
Q

HIV: helps decrease seroconversion after exposure

A

AZT (zidovudine, reverse transcriptase inhibitor) and ritonavir (protease inhibitor) within 1-2 hours of exposure

60
Q

MCC for laparotomy in HIV patients

A

Opportunistic infections.
MC: CMV
2nd MC: Neoplastic disease

61
Q

MC intestinal manifestation of AIDS (can present with pain, bleeding or perforation)

A

CMV colitis

62
Q

MC neoplasm in AIDS patients (although surgery rarely needed)

A

Kaposi’s sarcoma

63
Q

MC site of lymphoma in HIV patients

A

Stomach most common followed by rectum.

64
Q

Lymphoma in HIV patients is mostly due to …. and treatment is….

A

Mostly due to non-Hodgkin’s (B cell)

Tx: chemotherapy usual, may need surgery with significant bleeding or perforation

65
Q

GIB in HIV: lower or upper more common?

A

Lower more common than upper

66
Q

HIV: cause upper GIB

A

Kaposi’s sarcoma, lymphoma

67
Q

HIV: cause lower GIB

A

CMV, bacterial, HSV

68
Q

CD4 counts

  • Normal
  • Symptomatic disease
  • Opportunistic infections
A

Normal: 800 - 1200
Symptomatic: 300-400
Opportunistic: <200

69
Q

Hepatitis C Percentages

  • Chronic infection
  • Cirrhosis
  • Hepatocellular carcinoma
A
  • Chronic infection: 60%
  • Cirrhosis: 15%
  • HCCa: 1-5%
70
Q

Tx: brown recluse spider bites

A

Tx: dapsone initially, may need resection of area and skin graft for large ulcers later

71
Q

Acute septic arthritis:

  • Bugs?
  • Tx?
A
  • Bugs: Gonococcus, staph, H, influenza, strep

- Tx: Drainage, 3rd generation cephalosporin and vancomycin until cultures show organisms

72
Q

Diabetic foot infections

  • Bugs?
  • Tx?
A

Bugs: Mixed staph, strep, GNRs, anaerobes
Tx: broad-spectrum antibiotics (Unasyn)

73
Q

Bugs: found in cat and dog bites

Tx?

A

Pasteurella multocida

Tx: broad-spectrum antibiotics (Augmentin)

74
Q

Tx: peritoneal dialysis catheter infections

A

Tx: intraperitoneal vancomycin and gentamicin; increased dwell time and intraperitoneal heparin may help.

  • Remove catheter: peritonitis that lasts for 4-5 days.
  • Fecal peritonitis: requires laparotomy to find perforation