GI expressions of infectious disease II Flashcards
What is Primary Bacterial Peritonitis (PBP)? and what is the most common bacteria?
Fever, peritoneal irritation, >250 PMNs/uL in fluid
most common: Escherichia coli
What some causes of PBP?
- No apparent source of contamination (spontaneous)
2. Cirrhosis, ascites (liver fails to filter intestinal bacteria in portal blood)
What is the Tx of PBP?
start with: broad spectrum Abx covering both Gram - aerobic and Gram +
- 3rd gen cephalosporin
- prevent recurrence w Abx prophylaxis (fluoquinolones or sulfa)
What causes Secondary peritonitis due to perforation? What is the most common organism?
Mixed: Gram - facultative bacilli and anaerobes
endotoxin is produced from gram (-) = fever, shock, DIC
most common anaerobe = BACTEROIDES FRAGILIS
most common facultative = ECOLI
What are Sx of secondary Peritonitis due to Perforation
Sharp pain
Guarding, tenderness, rebound pain
Fever and leukocytosis
What is Tx for secondary Peritonitis due to Perforation? (mild/moderate, severe)
mild/moderate: broad-spectrum penicillin/clavulanate, 3rd gen cephalosporin, fluoroquinolone, w Metronidazole
Severe: carbapenem or combo
Surgery often needed
What is an abscess?
infection in which viable organisms and PMNs are contained in a fibrous capsule
What is so special about Bacteroides fragilis? what does it need to have successful infection?
Number one anaerobic isolate: 1. in intra-abdominal infections 2. in abdominal abscesses 3. isolated from blood needs a Facultative partner
Where are abscess usually found (when standing and laying down)
standing: pelvic cavity
laying down: Morrison’s pouch
What are way to identify abscess formation (3 ways)
- CT and sonographic scanning
- Gallium and indium labeled WBCs
- Barium enema - for unperforated abscess
What are four sources of infection for Liver abscess?
- seeding from peritonitis (ruptured appendix)
- infx of biliary tract (through ampulla)
- via portal vein
- Hematogenous (hepatic artery)
What are the common organisms associated with each source in Liver abscesses?
- Biliary
- Peritoneal
- Hematogenous
- Chemotherapy
- Portal
- Enterobacteriaceae, Enterococci
- mixed, w/ B. fragilis
- S. aureus or Streptococci
- C. albicans
- Entamoeba histolytica
What are clinical Sx of Liver Abscess?
- Fever (sometimes only Sx)
- RUQ pain
- Hepatomegaly, Jaundice
- Weightloss, nausea, vomiting
- elevated ALP, Aminotransferases (hepatocyte damage)
- Leukocytosis + anemia
- Bacteremia
What are 2 ways to identify Entamoeba histolytica?
- find cysts in feces
2. Ags (if in liver)
What is the Tx for liver abscesses (Candida, Amoeba)
drainage Candida: Amphotericin B Amoeba: 1. tissue trophozoites: Metronidazole 2. luminal cysts: Paromomycin
What is Necrotizing Fasciitis (NF)? When does it usually occur? and what are Sx?
Rapidly progressive infx of deep fascia w NECROSIS of subcutaneous tissue
occurs: after surgery or trauma
Sx: Erythema + pain disproportionate to physical findings
What is necrotizing fasciitis called in the perineal region?
Fournier gangrene
What are the causal organisms of Type I Necrotizing Fasciitis?
Average of 5 organisms per wound
Gram (-): Enterobacter, Bacteroides
Gram (+): Non-group A Strep, Clostridium, Peptostrep
Marine vibrios, (Vibrio vulnificus = salt water NF)
What causes Type II Necrotizing Fasciitis?
Streptococcus Pyogenes (combo w S. aureus, MRSA)
S. pyogenes produces TSST (toxic shock syndrome toxin) = stims production of TNF + cytokines
What are risk factors for Type I Necrotizing Fasciitis?
DM severe PVD Obesity Alcoholism IV drugs Bed sores (ulcers) penetrating trauma Abscess of female genital tract
What are risk factors for Type II Necrotizing Fasciitis?
DM severe PVD Recent Parturition (giving birth) Trauma VARICELLA
What are clinical Sx of Necrotizing Fasciitis?
RAPID prog:
erythema - bullae - ecchymosis - necrosis - gangrene
Skin: blue/black discoloration
edematous, WOODEN feel of subcutaneous tissue
High fevers
intense PAIN OUT OF PROPORTION to findings
Crepitus - gas in soft tissues
Infarct nerves = cutaneous anesthesia
What is cellulitis?
infection of skin and subcutaneous fat
What is Tx for Necrotizing Fasciitis?
Surgical Debridement Broad spectrum Abx Vancomycin - MRSA Metronidazole - Gram neg anaerobes Hyperbaric oxygen - anaerobes
