Chapter 5: Infection Flashcards Preview

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Flashcards in Chapter 5: Infection Deck (97):
1

MC immune deficiency.
Leads to infection.

Malnutrition

2

Microflora: stomach

Virtually sterile.
Some GPCs.
Some yeast.

3

Microflora: proximal small bowel

10^5 bacteria.
Mostly GPCs.

4

Microflora: distal small bowel

10^7 bacteria.
GPCs, GPRs, GNRs.

5

Microflora: Colon

10^11 bacteria.
Almost all anaerobes, some GNRs, GPCs.

6

MC organisms in the GI tract

Anaerobic bacteria (more common than aerobic bacteria in the colon 1,000:1)

7

MC anaerobe in the colon

Bacteroides fragilis

8

MC aerobic bacteria in the colon

Escherichia coli

9

MC source of fever within 48 hours

atelectasis

10

MC fever source 48 hours - 5 days

Urinary tract infection

11

MC fever source after 5 days

Wound infection

12

MCC gram negative sepsis

E coli

13

What toxin is release in gram negative sepsis?

Endotoxin (lipopolysaccharide lipid A) is released.

14

What does endotoxin release in gram negative sepsis?

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

15

Insulin / glucose: early vs late gram negative sepsis

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

16

Often occurs just before the patient becomes clinically septic

Hyperglycemia

17

Optimal glucose level in a septic patient

100 - 200 mg/dL

18

Clostridium difficile colitis
Dx: ?
Tx: ?

Dx: C difficile toxin
Tx:
Oral - vancomycin or flagyl
IV - Flagyl; lactobacillus can also help.
- Stop other antibiotics or change them

19

90% of abdominal abscess have...

Anaerobes

20

80% of abdominal abscess have...

Both anaerobic and aerobic bacteria

21

- Treated by drainage
- Usually occur 7-10 days after operation

Abscesses

22

When do you need antibiotics for abscess?

In patients with diabetes, cellulitis, signs of sepsis, fever, elevated WBC, or who have bioprasthetic hardware (e.g. mechanical valves, hip replacements)

23

Infection: % Clean (hernia)

2%

24

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

3 - 5%

25

Infection: % Contaminated (GSW to colon with repair)

5 - 10%

26

Infection: % Gross contamination (abscess)

30%

27

Purpose of prophylactic antibiotics
- Dosing?

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.

28

- Coagulase positive
- MC organism overall in surgical wound infections

Staphylococcus aureus

29

- Coagulase negative organism

Staphylococcus epidermidis

30

Released by staph species in an exopolysaccharide matrix

Exoslime

31

MC GNR in surgical wound infections

E coli

32

MC anaerobe in surgical wound infections
- Recovery from tissue indicates necrosis or abscess (only grows in low redox state)
- Also implies translocation from the gut

B. fragilis

33

How many bacteria are needed for wound infection?

> 10^5 bacteria.
- Less bacteria is needed if foreign body is present

34

Risk factors for wound infection

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

35

Surgical infections within 48 hours of procedure

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

36

MC infection in surgery patients
- Biggest risk factor?

UTI
- Biggest risk factor - urinary catheters: MC'ly - E coli

37

Leading cause of infectious death after surgery

Nosocomial pneumonia

38

What is nosocomial pneumonia related to?

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

39

MC organisms in ICU pneumonia

#1. S aureus
#2 Pseudomonas

40

#1 class of organisms in ICU pneumonia

GNRs

41

MCC line infections

#1. S epidermidis
#2. S. aureus
#3. Yeast

42

What central lines are at highest risk of infection?

Femoral lines

43

% Line salvage rate with infection

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

44

Diagnosis of line infection from central line culture

> 15 colony forming units = line infection -> need new site

45

- 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)

Necrotizing soft tissue infections

46

Pain out of proportion to skin findings, WBCs > 20, thin gray discharge, can have skin blistering / necrosis, induration and edema, crepitus or soft tissue gas on XR, can be septic

Necrotizing soft tissue infections

47

- 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.
- Beta hemolytic GAS has exotoxin
Tx?

Necrotizing fasciitis
- Tx: early debridement, high-dose penicillin, may want broad spectrum if thought to be polyorganismal

48

- 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?

C. perfringens infections
- Tx: early debridement, high dose penicillin

49

Pathophysiology C. perfringens infection

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

50

C. perfringens: toxin.

Alpha toxin

51

- Severe infection in perineal and scrotal area.
- Risk factors: DM, immunocompromised stat
- Caused by mixed organisms (GPCs, GNRs, anaerobes)
Tx?

Fournier's gangrene

Tx: early debridement, try to preserve testicles if possible; antibiotics.

52

When do you need fungal coverage in infection?

Need fungal coverage for positive blood cultures, 2 sites other than blood, 1 site with severe symptoms, endopthalmitis, or patients on prolonged bacterial antibiotics with failure to improve.

53

- Not a true fungus.
- Pulmonary symptoms most common; can cause tortuous abscesses in cervical, thoracic, and abdominal areas
Tx?

Actinomyces

Tx: drainage and penicillin G

54

- Not a true fungus
- Pulmonary and CNS symptoms most common
Tx?

Nocardia

Tx: drainage and sulfonamides (Bactrim)

55

Fungus: common inhabitant of the respiratory tract.
Tx?

Candida

Tx: fluconazole (some Candida resistant), anidulafungin for severe infections

56

Tx: aspergillosis

Voriconazole for severe infections

57

Tx: histoplasmosis
(pulmonary symptoms usual; Mississippi and Ohio River Valleys)

Liposomal amphotericin for severe infections

58

- CNS symptoms most common; usually in AIDS patients.
Tx?

Cryptococcus

Tx: Liposomal amphotericin for severe infections.

59

- Pulmonary symptoms
- Southwest
Tx?

Coccidioidomycosis

Tx: liposomal amphotericin for severe infections

60

Risk factor for spontaneous bacterial peritonitis (SBP; primary)

Low protein (

61

Organisms in primary SBP

Monobacterial
- 50% E. coli
- 30% Streptococcus
- 10% Klebsiella

62

Pathophysiology of primary spontaneous bacterial peritonitis

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

63

Cultures in primary spontaneous bacterial peritonitis

Fluid cultures are negative in many cases

64

Dx: primary spontaneous bacterial peritonitis

PMNs > 500 cells/cc diagnostic

65

Primary spontaneous bacterial peritonitis:
Tx?
Prophylaxis?

Tx: Ceftriaxone or other 3rd generative cephalosporin

Prophylaxis: fluoroquinolonges good (norfloxacin)

66

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

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

67

- Intra-abdominal source (implies perforated viscus)
- Polymicrobial (B fragilis, E coli Enterococcus MC organisms)
Tx?

Secondary bacterial peritonitis

Tx: Usually need laparotomy to find source

68

Exposure risk: HIV blood transfusion

70%

69

Exposure risk: infant from positive mother with HIV

30%

70

Exposure risk: Needle stick form HIV positive patient

0.3%

71

Exposure risk: HIV positive Mucous membrane exposure

0.1 %

72

HIV: helps decrease seroconversion after exposure

AZT (zidovudine, reverse transcriptase inhibitor) and ritonavir (protease inhibitor)

73

When do you dose antivirals after HIV exposure?

Within 1-2 hours of exposure

74

MCC for laparotomy in HIV patients

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

75

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

CMV colitis

76

MC neoplasm in AIDS patients (although surgery rarely needed)

Kaposi's sarcoma

77

MC site of lymphoma in HIV patients

Stomach most common followed by rectum.

78

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

Mostly due to non-Hodgkin's (B cell)
Tx: chemotherapy usual, may need surgery with significant bleeding or perforation

79

GIB in HIV: lower or upper more common?

Lower more common than upper

80

HIV: cause upper GIB

Kaposi's sarcoma, lymphoma

81

HIV: cause lower GIB

CMV, bacterial, HSV

82

CD4 counts
- Normal
- Symptomatic disease
- Opportunistic infections

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

83

- Now rarely transmitted with blood transfusion (0.0001%/unit)
- 1% - 2% of population infected
- Fulminant hepatic failure rare.
- Interferon may help prevent development of cirrhosis

Hepatitis C

84

Hepatitis C Percentages
- Chronic infection
- Cirrhosis
- Hepatocellular carcinoma

- Chronic infection: 60%
- Cirrhosis: 15%
- HCCa: 1-5%

85

Tx: brown recluse spider bites

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

86

Acute septic arthritis:
- Bugs?
- Tx?

- Bugs: Gonococcus, staph, H, influenza, strep
- Tx: Drainage, 3rd generation cephalosporin and vancomycin until cultures show organisms

87

Diabetic foot infections
- Bugs?
- Tx?

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

88

Bug: found only in human bites, can cause permanent joint injury.
Tx?

Human bite

Tx: Broad-spectrum antibiotics (Augmentin)

89

Bugs: found in cat and dog bites
Tx?

Pasteurella multocida

Tx: broad-spectrum antibiotics (Augmentin)

90

MCC impetigo, erysipelas, cellulitis, folliculitis

Staph and strep most common

91

- Boil
- Usually S. epidermidis or S. aureus
Tx?

Furuncle

Tx: drainage +/- antibiotics

92

Multiloculated furuncle

Carbuncle

93

MCC peritoneal dialysis catheter infection

S. aureus and S. epidermidis

94

Tx: peritoneal dialysis catheter infections

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

95

Risk factors: sinusitis

Nasoenteric tubes, intubation, patients with severe facial fractures. Usually polymicrobial.

96

Sinusitis:
CT?
Tx?

CT head: shows air-fluid levels in the sinus
Tx: broad-spectrum antibiotics; rare to have to tip sinus percutaneously for systemic illness

97

Clippers vs razors?

Use clippers preoperatively instead of razors to decrease chance of wound infection