.

     

     

     

    microbioSmall.png

     

     

     

    Gram +

    Gram -

     

    Cocci

    Bacilli

    Cocci

    Bacilli

    Aerobes

    Staphylococcus aureus

     

    Streptococcus pneumoniae

     

    Steptococcus pyogenes

     

    Enterococcus fecalis

    Lactobacillus

     

    Listeria

     

    Corynebacteria

    (C. diphtheriae)

    Neisseria gonorrheae

    Neisseria meningitides

     

    Moraxella

    E. coli

     

    Pseudomonas

     

    Klebsiella

     

    H. influenza

     

     

    Legionella

    Anaerobes

    Peptostreptococcus

    Clostridium

     

    Bacteroides fragilis

     

     

     

     

    Normal Flora

    • Skin
      • Staphylococcus spp
      • Corynebacterium spp.
      • Propionibacterium acnes
      • Bacillus spp.
    • Oropharynx
      • Viridans group streptococci
      • Neisseria spp.
      • Peptostreptococcus spp.
      • Oral spirochetes
    • Large Intestine
      • Enterococcus spp.
      • Enteric bacilli/Enterobacteriaceae
        • Escherichia coli, Klebsiella spp.

    Specific Syndromes

    Toxic Shock Syndrome

    • Caused by toxins produced by Staph and Strep.
      • NOTE: Any B-hemolytic strep can cause this, but strep pygenes is most common 
    • Historically associated with specific tampon and "menstruation associated toxic shock syndrome"
      • Also common in:
        • Surgical/Obstetrical Wound Infections
        • Sinus Infection (nasal packing).
        • Osteomyelitis
        • Skin Ulcers
        • Burns
        • Pneumonia
        • IVDU.
    • Clinical Features:
      • Chills, fever, malaise, erythematous rash, hypotension
      • Multi-Organ Involvement.
      • Diagnostic Criteria of Toxic Shock Syndrome:
        • Diagnostic Criteria for Toxic Shock Syndrome

          • 1. Fever > 38.9 (>102F)
          • 2. sBP < 90 mmHg
          • 3. Diffuse macular rash + desquamasion (usually on palms and soles)
                (but usually occurs 5-7 days after onset).
          • 4. Involvement of 3 organ systems:
            • GI: nausea, vomiting, diarrhea
            • MSK: Severe myalgia, 5-fold rise in CK,
            • Mucous membranes -hyperemia of vagina, conjunctivae or pharynx
            • Kidney: BUN/Creat elevation > 2x ULN
            • Liver: Bilirubin, AST, ALT >2x ULN
            • Blood: Platelet < 100,000/uL
            • CNS: Disorientation w/o focal neuro signs.
      • R/O (DDx)
        • Rocky Mountain Spotted Fever
        • Leptospirosis
        • Measles
        • Consider CSF cultures.
    • Streptococcal Toxic Shock:
      • Definite: Isolation of GABHS in sterile site
      • Probable: Isolation of GABHS in non-sterile site.
      • Also need hypotension + 2 of following findings:
        • Kidney (AKI), Liver (transaminases), Skin (erythematous macular rash/soft tissue necrosis), Blood (coagulopathy, thrombocytopenia, DIC), Pylmonary (ARDS).
    • Treatment:
      • Early supportive therapy.
      • Treatment of underlying infection.
      • Surgery
        • Removal of foreign body + debridement).
      • Empric Abx:
        • Same as necrotizing fasciitis:
          • Ensure clindamycin is used.
      • IVIG = sometimes recommended (better survival from observational data). 
      • Hyperbaric oxygen =  can be helpful, but not enough studies.
      • Some cases of secondary transmission:
        • Consider penicillin prophyaxis for:
          • Household contacts
          • >65yo
          • High risk conditions (DMII, CAD, cancer, HIV, steroids etc..).

    Specific Pathogens

    CA-MRSA

    • Community Acquired Methycillin Resistant Staph Aureus.
    • Causes:
      • Purulent skin and soft tissue infections. 
      • Pneumonia (less common).
    • Risk Factors:
      • Athletes
      • Prisons Inmates.
      • MSM
      • Children at Daycare Centers
      • Injection Drug Users
      • Homeless
      • Military Personnel (crowded conditions)
    • CA-MRSA replacing HA-MRSA.
    • Treatment:
      • I&D for cutaneous abscess
      • Abx recommended for:
        • Young
        • Elderly
        • Multiple sites of infection 
        • Comorbidities / Immunosuppression is present.
        • Quickly progressing
        • Poor response to I&D.
        • Abscesses in difficult-to-drain locations (face, genitals, hand).
      • Empiric Therapy for CA-MRSA indicated for: Purulent Cellulitis.
        • Clindamycin (high resistance, look at local resistance rates, avoid if >10-15%)
        • TMP/SMX
        • Tetracyclines
        • Linezolid
      • NOTES:
        • Fluoroquinolones (NOT recommended due to easy MRSA resistance and high rate of resistance in many areas)
        • Only clindamycin and Linezolid reliably cover B-hemolytic strep.  So if treating celluitis with Septra and Tetracyclines, may need to add a 2nd agent.
    • Other times to empirically cover MRSA (along with broad-spectrum antibiotics).
      • Specific conditions:
        • Deep infection
        • Infected burns/ulcers
        • Surgical wound infections
        • Surgical debridement
      • Surgical debridement and appropriate board spectrum abx including MRSA coverage:
        • Vancomycin
        • Daptomycin
        • Telavancin
        • Ceftaroline
        • Linezolid
    • NOTE: New Trial:
      • Talan et al (NEJM 2016) -> Patients with abscesses present <1w measured ≥2.0cm and no associated cellulitis --> treated with septra do better.  (previously drainage was thought to be sufficient)
        • If MRSA risk patient has abscess ≥2.0cm (even if no cellulitis), consider Septra.

    HA-MRSA

    • Hospital Acquired Methycillin Resistant Staphylococcus Aureus
    • Has more antimicrobial resistance than CA-MRSA

     

     

    Mycobacterium Marinum

    • Marine organism present in fresh and salt water.
    • Skin puncture, such as a fish hook, or handling fish.
    • Usually localized to area of puncture (skin tendons, adjacent joints).  Nodular papules can form, ulcerate.
    • High index of suspicion if antibiotic unresponsive cellulitis.
    • Diagnosis:
      • Culture of synovial fluid or synovial biopsy.

     

    SPICE-M Bugs

    • S - Serratia
    • P - Providentia
    • I - Indole Positive Proteus (P. Vulgaris, P. penerjj, NOT P. Mirabilis)
    • C - Citerobacter
    • E - Enterobacter
    • M - Morganella
    • These bugs appear to be sensitive to B-Lactams, but have an inducible B-lactamase.
    • Treat with:
      • Nitrofurantoin
      • Septra
      • Carbapenems
      • Fluoroquinolones
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