Chapter 5 - Infection Flashcards
What is the most common immune deficiency?
Malnutrition
What is the microflora of the stomach?
Virtually sterile; some GPCs, some yeast
What is the microflora of the proximal small bowel?
10^5 bacteria, mostly GPCs
What is the microflora of the distal small bowel?
10^7 bacteria, GCPs, GPRs, GNRs
What is the microflora of the colon?
10^11 bacteria, almost all anaerobes, some GNRs, GPCs
What is the most common organism in the GI tract?
Anaerobes - Bacteroides
What is the most common aerobic bacteria in the colon?
E. coli
What is th emost common cause of gram-negative sepsis?
E. coli
What type of toxin is released by E. coli, what are its effects?
Endotoxin (lipopolysaccharide lipid A); triggers the release of TNF-alpha from macrophages, activates complement and coagulation cascade
What is the optimal glucose level in a septic patient?
100-120 mg/dL
What is the dx and tx of C. diff colitis?
Dx: fecal leukocytes in stool, C. diff toxin; Tx: oral vanco or flagyl, IV flagyl, lactobacillus
What percentage of abdominal abscesses have anaerobes?
90%
What percentage of abdominal abscesses have both anaerobic and aerobic bacteria?
80%
How many days post-op do abdominal abscesses occur?
7-10d
In which patients to antibiotics need to be started with abdominal abscesses?
DM, cellulitis, clinical signs of sepsis, fever, elevated WBC, bioprosthetic hardware
Wound infections develop in what percentage of clean (hernia) cases?
2%
Wound infections develop in what percentage of clean contaminated cases(elective colon resection w/ prepped bowel)?
3-5%
Wound infections develop in what percentage of contaminated cases (GSW to colon w/ repair)?
5-10%
Wound infections develop in what percentage of grossly contaminated cases (abscess)?
30%
What is the most common organism overall in surgical wound infections?
Staph aureus (coagulase positive)
What is exoslime?
Exopolysaccharide matrix released by staph species
What is the most common GNR in surgical wound infections?
E. coli
What is the most common anaerobe in surgical wound infections?
B. fragilis; presence indicates necrosis or abscess, implies translocation from gut
How many bacteria are needed to create a wound infection?
> 10^5, less needed if foreign body present
What are the risk factors for wound infections?
Long operations, hematoma/seroma formation, advanced age, chronic disease (COPF, renal/liver failure, DM), malnutrition, immunosuppressive drugs
What is the most common nonsurgical infection
UTI (most commonly E. coli), urinary catheters the biggest risk factor
What is the leading cause of infectious death after surgery?
Nosocomial pneumonia
What are the most common organisms in ICU pneumonia?
1 S. aureus, #2 Psuedomonas
What is th emost common class of organisms in ICU pneumonia?
GNR
What are the msot common organisms in line infections?
1 S. epidermidis, #2 S. aureus, #3 yeast
What is the line salvage rate with antibiotics?
50%, less with yeast infections
Which organisms are found in necrotizing soft tissue infectons?
Beta-hemolytic Strep (group A), C. perfringens, mixed organisms
Organisms found in necrotizing faciitis?
Beta-hemolytic Strep, can be polyorganismal
What are the signs of necrotizing fasciitis?
Overlying skin pale red, progress to purple with blisters; thin, gray, foul-smelling drainage, crepitus
What is the treatment of necrotizing fasciitis?
Early debridement, high-dose penicillins, broad spectrum if thought to be polyorganismal
How does necrotic tissue set up an environment for C. perfringens infections?
Decreases oxidation-redux potential
C. perfringens has what type of toxin?
alpha toxin
What will a gram stain show with C. perfringens infection?
GPRs without WBCs
What organisms are found in Fournier’s gangrene?
Mixed organisms (GPCs, GNRs, anaerobes)
When do you cover for fungal infection?
Positive blood cultures, 2 sites other than blood, 1 site with severe symptoms, endophthalmitis, pts on prolonged bacterial abx without improvement
Type of abscess caused by Actinomyces (not a true fungus)?
Tortuous abscesses in cervical, thoracic, abdominal areas; most commonly with pulmonary symptoms
Treatment for Actinomyces?
Drainage and penicillin G
Sympoms wtih Nocardia (not a true fungus)?
Pulmonary and CNS
Treatment for Nocardia?
Drainage and sulfonamides (bactrim)
Symptoms with Histoplasmosis?
Pulmonary most common; Mississippi and Ohio River valleys
Treatment for Histoplasmosis?
Amphotericin for severe infections
Symptoms with Cryptococcus?
CNS most common
Treatment for Cryptococcus?
Amphotericin for severe infections
Symptoms with Coccidioidomycosis?
Pulmonary; Southwest
Treatment for Coccidioidomycosis?
Amphotericin for severe infections
Spontaneous (primary) bacterial peritonitis is secondary to what?
Decreased host defenses (intrahepatic shunting, impaired bactericidal activity in ascities); NOT due to transmucosal migration
SBP is caused by which organisms?
Monobacterial: 50% E. coli, 30% Strep, 10% Klebsiella
What test on the tap is diagnostic of SBP?
PMNs > 500cells/cc
Treatment for SBP?
Ceftriaxone or other 3rd generation cephalosporin
What is used for short term prophylaxis against SBP?
Fluoroquinolones (cipro)
What causes secondary bacterial peritonitis?
Intra-abdominal source (transmucosal migration, perforated viscus); polymicrobial, B. fragilis, E. coli, Enterococcus
Treatment for secondary bacterial peritonitis?
Laparotomy
Chance of contracting HIV with HIV+ blood transfusion?
70%
Chance of infant contracting HIV from positive mother?
30%
Chance of contracting HIV from needle stick?
0.3%
Chance of contracting HIV from mucous membrane exposure?
1%
What is the most common cause for laparotomy in HIV patients?
Opportunistic infections (CMV most common)
What is the most common intestinal manifestation of AIDS?
CMV colitis (pain, bleeding or perforation)
Most common organ affected by lymphoma in HIV patients?
Stomach, followed by rectum (mostly Non-Hodgkin’s, 70% B cell)
What causes GI bleeds in HIV patients?
Upper: Kaposi’s sarcoma; Lower: CMV, bacterial, HSV (lower more common)
What are the CD4 counts in normal, symptomatic disease, and opportunistic infections?
Normal: 800-1200; Symptomatic disease: 300-400; Opportunistic infections: 200
Chronic infection occurs in what % of Hep C patients?
60%
Cirrhosis occurs in what % of Hep C patients?
15% over 20y
HCC occurs in what % of Hep C patients?
1-5%
Treatment of brown recluse spider bites?
Dapsone; may need resection of area/skin graft for large ulcers
What organisms cause acute septic arthritis?
Gonococcus, staph, H. flu, strep
Treatment of acute septic arthritis?
Drainage, 3rd-gen cephalosporins and vanco
What organisms cause diabetic food infections?
Mixed staph, strep, GNRs, anaerobes
Treatment of diabetic foot infections?
Broad spectrum abx: Unasyn, Zosyn
What organism is found in human bites?
Eikenella, can cause pernament joint inujury
What organism is found in dog/cat bites?
Pasturella multocida
Treatment for human/dog/cat bites?
Broad-spectrum abx: Augmentin
Most common organisms for impetigo, erysipelas, cellulitis, folliculitis?
Staph and strep
Most common organisms in PD cath infections?
S. aureus, S. epidermidis
Treatment of PD cath infections?
Intraperitoneal vanco/gent; removal of catheter for peritonitis that lasts for 4-5d
Risk factors for sinusitis?
Nasoenteric tubes, intubations, facial fractures