Fiser Chapter 5 INFECTION Flashcards
Stomach microflora
Virtually sterile, some GPCs and yeast
Proximal small bowel microflora
10^5 bacteria, mostly GPCs
Distal small bowel microflora
10^7 bacteria, GPCs, GPRs, GNRs
Colon microflora
10^11 bacteria, almost all anaerobes, some GNRs, GPCs
Most common bacteria in GI tract
Bacteroides fragilis (anaerobe)
Most common aerobe: E coli
Postop fever and infection
Hours: NSTI
2 days: atelectasis
2-5 days: UTI (most common postop infection)
>5 days: wound infection
If within 2 days, its because of injury to bowel or invasive STI (C perfringens or beta-hemolytic strep)
7-10 days abscess
GN sepsis
E coli -> endotoxin (LPS lipid A) -> TNF-alpha release from macrophages -> complement activation -> coagulation cascade
Infection and blood glucose
Hyperglycemia often just before clinical sepsis
Early GN sepsis: decreased insulin, increased glucose
Late GN sepsis: increased insulin and glucose
Optimal blood glucose in sepsis
100-120 mg/dL
C diff colitis treatment
Oral vanc or flagyl
IV flagyl
Lactobacillus can also help
Stop or change other abx
Abscess bacteria
90% anaerobes
80% both anaerobes and aerobes
Abscess tx
I&D
Antibiotics if DM, cellulitis, clinical sepsis, fever, leukocytosis, or bioprosthetic hardware (valve, hip)
Expected wound infection rates
Clean: 2%
Clean contaminated 3-5%
Contaminated 5-10%
Gross contamination 30%
Prophylactic abx timing
24hr after OR
48hr after OR for cardiac cases
SSI bacteria
- Definition >/= 10^5 bacteria. Less if foreign body present.
- Most common organism S aureus (coagulase positive)
COPS
S aureus
CONS
S epidermidis
Exoslime
Exopolysaccharide matrix released by Staph species
B frag in SSI
indicates necrosis or abscess (only grows in low redox state) and/or translocation from gut
Risk factors for SSI
Long operation Hematoma or seroma Old Chronic disease (COPD, RF, LF, DM) Malnutrition (most common immunodeficiency) Immunosuppression
Leading cause of infectious death after surgery
nosocomial PNA
Nosocomial PNA bacteria
- Staph aureus
- Pseudomonas
But GNRs #1 class of organisms in ICU PNA?
Line infection bacteria
- Staph epidermidis
- Staph aureus
- Yeast
Central line cx indicative of line infection
> 15 colony forming units
Central line infection dx and tx
Dx: >15 CFU or site looks bad
Tx: move to new site, or just PIV if possible
NSTI organisms
Beta-hemolytic GAS (exotoxin)
C perfringens
Mixed
NSTI clinical findings
Pain out of proportion WBC >20 Thin gray drainage Skin blistering/necrosis Induration and edema Crepitus or ST gas on XR Sepsis +/-
Overlying skin pale red, progressing to purple with blister or bullae
NSTI
NSTI tx
Early debridement
High dose PCN
Broad spectrum abx if poly-organismal
Necrotic tissue, pain out of proportion, gram stain shows GPRs without WBCs –> myonecrosis and gas gangrene
C perfringens NSTI
Farming injury -> necrotic tissue decreases redox -> good environment for C perfringens -> alpha toxin -> myonecrosis and gas gangrene
C perfringens tx
High dose PCN and early debridement
Perineal and scrotal severe infection
- Fournier’s gangrene
- GPCs, GNRs, anaerobes
- Tx: early debridement, try to preserve testicles, antibiotics
Tortuous abscess in cervical, thoracic, or abdominal area
Actinomyces
Tx: drain and PCN G
Actinomyces abx
Penicillin G
Pulmonary and CNS symptoms, branching bacteria
Nocardia
Drain and bactrim
Nocardia abx
Bactrim
Candida abx
Fluconazole; sometimes anidulafungin for severe infections
Aspergillosis abx
Voriconazole
Histoplasmosis abx
Mississippi and Ohio River valley
Pulmonary symptoms
Tx: liposomal amphotericin for severe infection
Cryptococcus
CNS symptoms in AIDS
Tx: liposomal amphotericin for severe infection
Coccidioidomycosis
Southwest, pulm symptoms
Tx: liposomal amphotericin for severe infection
Primary SBP risk factor
SBP organisms
E coli Streptococcus Klebsiella Fluid cultures often negative PMNs>500 cells/cc diagnostic
Secondary bacterial peritonitis: polymicrobial (B frag, E coli, enterococcus)
SBP ppx and tx
ppx: Fluoroquinolones (norfloxacin)
tx: Ceftriaxone
Secondary bacterial peritonitis
Perforated viscus
Polymicrobial
Need ex-lap
Risk of HIV if needle stick from positive patient
0.3%
Risk of HIV if mucous membrane exposure
0.1%
HIV exposure ppx
Zidovudine and ritonavir (RTI and PI)
Most common causes for ex-lap in HIV patients
- Opportunisitic infection (CMV)
2. Neoplastic disease
AIDS patient with pain, bleeding, and perforation
CMV colitis
Most common intestinal manifestation of AIDS
Most common neoplasm in AIDS
Kaposi’s sarcoma
HIV lymphoma sites
- Stomach
- Rectum
Mostly NHL (B cell)
Tx: chemo
GIB in HIV patient
LGIB more common: CMV, bacterial, HSV
UGIB: Kaposi’s sarcoma, lymphoma
CD4 counts
Normal: 800-1200
Symptomatic HIV: 300-400
Opportunistic infection:
Risk of HepC with blood transfusion
.0001%
HepC infection types
Chronic 60%
Cirrhosis 15% (interferon may help prevent)
HCC 1-5%
Brown recluse spider bite infection tx
Dapsone
May need resection of area and skin graft for large ulcers later
Acute septic arthritis bacteria and empiric tx
Gonococcus, staph, H influenzae, strep
Drainage
Vanc/ceftriaxone
DM foot infection bacteria and tx
Mixed staph, strep, GNRs, anaerobes
Tx: Broad spectrum abx, e.g. Unasyn
Cat/dog/human bite bacteria and tx
Polymicrobial
Eikenella only in human bites -> permanent joint injury
Pasteurella multocida in cat and dog bites
Tx: broad spectrum abx, e.g. Augmentin
Impetigo, erysipelas, cellulitis, folliculitis organism
staph and strep most commonly
Furuncle boils organism and tx
S epidermidis or S aureus
Tx: drainage +/- abx
Carbuncle
multiloculated furuncle
Peritoneal dialysis catheter infection bacteria and tx
- S aureus and S epidermidis most commonly
- Fungal (hard to treat)
Tx: intraperitoneal vanc/gentamicin; increased dwell time and intraperitoneal heparin may help; removal if peritonitis lasts >4-5 days
Sinusitis risk factors, bacteria, dx, tx
Nasoenteric tubes
Intubation
Severe facial fractures
Usually polymicrobial
HCT air-fluid levels in sinus
Tx: Broad-spectrum abx, rarely percutaneous tap
