Aeromonas Hydrophila

CNN LINK: So I had to embark upon understanding this flesh eating necrotizing fasciitis causing bacteria that has the life of Aimee Copeland on hold and on a ventilator in a hospital in Augusta, GA.   Only 24 years old, Aimee fell from a zip line and had a gash in her leg that was stitched up only to return to an ER a few days later with a bigger issue.  Necrotizing fasciitis.

Aeromonas hydrophila is a heterotrophic, Gram-negative, rod shaped bacterium, mainly found in areas with a warm climate. This bacterium can also be found in fresh, salt, marine, estuarine, chlorinated, and un-chlorinated water. Aeromonas hydrophila can survive inaerobic and anaerobic environments. This bacterium can digest materials such as gelatin, and hemoglobin. Aeromonas hydrophila was isolated from humans and animals in the 1950s. This bacterium is the most well known of the six species of Aeromonas. It is also highly resistant to multiple medications, chlorine, and cold temperatures.

Because of Aeromonas hydrophila’s structure, it is very toxic to many organisms. When it enters the body of its victim, it travels through the bloodstream to the first available organ. It produces Aerolysin Cytotoxic Enterotoxin (ACT), a toxin that can cause tissue damage.

Most of the time, this organism causes gastroenteritis.

Aeromonas is usually found in freshwater and marine environments; it is most prominent in the Northern Hemisphere during the warmer months. The skin of the lower extremities is the most common site of infection, usually after traumatic exposure to contaminated water or soil. Aeromonas infection and cellulitis often develop within 8 to 48 hours of exposure, and systemic signs are common. Manifestations may include hemorrhagic bullae, subcutaneous bleeding, and purpura.

Aeromonas is typically highly susceptible to penicillins combined with β-lactamase inhibitors, second- and third-generation cephalosporins, aminoglycosides, and fluoroquinolones.

When patients do not respond to antibiotics for presumed common cellulitis, it may be prudent to obtain further imaging such as CT or MRI of the affected limb to rule out soft tissue collections, soft tissue emphysema, and necrotizing fasciitis. Surgical debridement may be indicated for deep soft tissue infection, necrosis, and purulent collections that are inadequately draining.

I do hope Aimee makes a full recovery.  You can follow here progress here.

Meet Mr. MRSA

I thought I would introduce you to an infectious organism every week!  Today, the lucky "bug" as they are referred to in the medical community is methicillin resistant staphylococcus aureus (MRSA). If I was a common layperson in the field of medicine, I would view this microorganism as a very nasty flesh eating entity.  I thought I would shed some light about MRSA.  Whether you are dealing with a soft tissue infection, pneumonia, central nervous system infection, endocarditis (heart), or bone and joint, the treatment differs.

Methicillin-resistant Staphylococcus aureus (MRSA) is a bacterium that causes infections in different parts of the body. It's tougher to treat than most strains of staphylococcus aureus -- or staph -- because it's resistant to some commonly used antibiotics.

The symptoms of MRSA depend on where you're infected. Most often, it causes mild infections on the skin, causing sores or boils. But it can also cause more serious skin infections or infect surgical wounds, the bloodstream, the lungs, or the urinary tract.

Though most MRSA infections aren't serious, some can be life-threatening. Many public health experts are alarmed by the spread of tough strains of MRSA. Because it's hard to treat, MRSA is sometimes called a "super bug."  Methicillin-resistant Staphylococcus aureus (MRSA) is a bacterium that causes infections in different parts of the body. It's tougher to treat than most strains of staphylococcus aureus -- or staph -- because it's resistant to some commonly used antibiotics.

The symptoms of MRSA depend on where you're infected. Most often, it causes mild infections on the skin, causing sores or boils. But it can also cause more serious skin infections or infect surgical wounds, the bloodstream, the lungs, or the urinary tract.

Though most MRSA infections aren't serious, some can be life-threatening.  Many public health experts are alarmed by the spread of tough strains of MRSA.  Because it's hard to treat, MRSA is sometimes called a "super bug." 

Also just news today... an almost instant test in detecting MRSA.

Skin and soft-tissue infections

1.  Abscess  - incision and drainage
2. Purulent cellulitis
   • Clindamycin 300-450 mg PO TID (C diff)
   • Bactrim 1-2 DS tablets BID (pregnancy category C/D)
   • Doxycycline 100 mg BID (pg category D and not recommend for children under 8)
   • Minocycline 200 mg x 1, then 100 mg PO BID
   • Linezolid 600 mg BID (expensive)
3.  Nonpurulent cellultis
   • Beta lactam (cephalexin and dicloxacillin) 500 mg QID
   • Clindamycin 300-450 mg TID
   • Beta lactam and/or Bactrim or a tetracycline – amoxicillin 500 mg TID
   • Linezolid 600 mg BID
4. Complicated SSTI
   • Vancomycin 15-20 mg/kg/dose IV every 8-12 hours
   • Linezolid 600 mg PO/IV BID
   • Daptomycin (cubicin) 4 mg/kg/dse IV QD
   • Telavancin 10 mg/kg/dose IV QD
   • Clindamycin 600 mg PO/IV TID
5. Bacteremia
   • Vancomycin 15-20 mg/kg/dose IV every 8-12 hours
   • Daptomycin 6 mg/kg/dose IV QD
6. Infective endocarditis, native valve – same as bacteremia
7. Infective endocarditis prosthetic valve
   • Vancomycin and gentamicin and rifampin – 15-20 mg/kg/dose IV every 8-12 hrs,                                          i.      1 mg/kg/dose IV every 8 h,  300 mg PO/IV every 8 h
8.  Persistant bacteremia
9. Pneumonia
   • Vancomycin 15-20 mg/kg/dose IV every 8-12 hours        
   • Linezolid 600 mg PO/IV BID
   • Clindamycin 600 mg PO/IV TID
10. Osteomyelitis (Bone and Joint Infections)
    • Vancomycin 15-20 mg/kig/dose IV every 8-12 hours
    • Daptomycin 6 mg/kg/day IV QD
    • Linezolid 600 mg PO/IV BID
    • Clindamycin 600 mg PO/IV TID
    • TMP-SMX and rifampin – 3.5-4.0 mg/kg/dose PO/IV every 8-12 h
11. Septic arthritis
    • Vancomycin 15-20 mg/kg every 8-12 hours
    • Daptomycin 6 mg/kg/day IV QD
    • Linezolid 600 mg PO/IV BID
    • Clindamycin 600 mg PO/IV TID
    • Bactrim 3.5-4.0 mg/kg/dose PO/IV every 8-12 hours
12. Meningitis
    • Vancomycin 15-20 mg/kg/dose IV every 8-12 hours
    • Linezolid 600 mg PO/IV BID
    • Bactrim 5 mg/kg/dose PO/IV every 8-12 hours
13. Brain abscess, subdural empyema, spinal epidural abcess
    • Vancomycin 15-20 mg/kg/dose every 8-12 hours
    • Linezolid 600 mg po/iv BID
    • Bactrim 5 mg/kg/dose PO/IV every 8-12 hours
14. Septic thrombosis of cavernous or dural venous sinus
    • Vanc same
    • Zyvox
    • Bactrim same

Move Over MRSA...

Right now there are very few antibiotic treatments for these newer "super bugs" that just happen to be gram negative.  Imagine having another infection, the one that is a nuisance but ends up killing you.  It's happening today -- something like a simple UTI taking your life.  It's unthinkable. Doctors see gram-negative infections among patients who are already very ill. Might be babies in the NICU, very old patients, patients who've just had surgery, burn patients in the ICU, for example. Gram-negative bacteria can enter the body by way of catheters, IVs, ventilators or wounds.  And the drugs to treat them are few and far between.  Keep in mind MRSA started in the hospital.  Same for this new category.

If you are like my many friends, as soon as you get a sniffle or UTI, you head into the doctor's office to get a round of antibiotics.  Stop...  do you really need them?  OK, I try not to blame the lay public for this.  I blame the physicians.  Stop giving in to the patient and find out if they really have an infection before giving them an antibiotic for a virus. Like with MRSA, not overprescribing antibiotics; that's how these bacteria learn how to adapt and become less treatable.

More reading.