Staphylococcus or, as it’s more widely known, staph, is one of the most common bacteria
found on humans around the world. In some cases, it can pose a real threat to your body’s
immune system - even proving lethal. So, if it’s so widespread,
why aren’t we all getting infected?
- Hi, my name is Vance Fowler. I'm an infectious disease doctor in the division of infectious
diseases at Duke University Medical Center. For the last twenty years or so, I've focused
on the clinical care, and the research around drug-resistant bacteria,
and staph aureus in particular.
Staphylococcus is a bacteria that lives on our skin. And about 40% of people on the planet
carry it on their body but are asymptomatic. So almost half of us are walking around unaware
that we’re carriers of staph.
And usually that’s just fine.
- There are many different kinds of staph, but the one that causes the greatest amount
of problems in human medicine is a bacteria called staphylococcus aureus. This is generally
the bacteria that people are referring to when they talk about a staph infection.
Staph aureus can be colonized in the nose, armpits, genital areas, and other parts of
the skin. And this colonization can go on for years, with the patient being totally
asymptomatic throughout much of their lives.
- Sometimes, for reasons that we really don't completely understand yet, this staph will
change from being a bystander to being trouble.
And when it makes that change, that trouble becomes an infection in your skin or soft tissues.
How this usually happens is with a break in the skin, allowing the infection
to enter the body and the bloodstream.
- And once you get staph in your blood, or staph aureus bacteremia, then things get a
lot more serious. The reason it gets serious is because now it has access to infect and
cause an infection in virtually any site in the body.
For example, it can cause pneumonia and involve the lungs. It can cause infections
in your bone, called osteomyelitis, and it can cause joint infections, cause arthritis,
and it can cause infections of your heart, cause endocarditis.
And this is what makes it unique in the bacterial world - its ability to cause a wide range
of medical concerns. This is because staph aureus has what are called virulence factors,
or things that allow it to cause infection.
- Basically, though, all of its virulence factors fall into one of two categories.
They're either adhesions,
which are proteins that allow the bacteria to stick to things that it doesn't need to
stick to, like heart valves, spines, bone... or toxins, which, generally speaking, are
involved in causing local damage to cells and tissue. So it will cause cell rupture,
cause tissue to break down and die.
With the help of these virulence factors, the bacteria can turn lethal
once it gets into the bloodstream.
- So wow, I know that sounds scary, and it is pretty serious. How do you know you have
a staph infection? The key thing about a staph infection is you're going to have
symptoms in the site that's involved.
Because staph mostly impacts the soft tissue, infections can look like a boil or abscess
that’s red, hot, swollen or seeping. Fortunately, these can mostly be treated with antibiotics.
- Some of the other forms of infection may be a little more subtle, and they may require
diagnosis in the hospital or in the emergency room. If you get staph in your bloodstream,
really the hallmark finding is fever and chills.
There’s another type of staph that is even more alarming: MRSA, or Methicillin-Resistant
Staphylococcus Aureus. It’s a concern not just because of its resistance to antibiotics,
but also because it’s showing signs of spreading into new territory.
- The epidemiology of MRSA has also changed over the years. Traditionally it was associated
almost exclusively with patients who had been in the hospital, or patients who had ongoing
contact with the medical system, for example, long-term care facilities, hemodialysis patients,
things like that.
But about fifteen years ago, something happened. People with absolutely no contact with the
health care system began to develop boils and abscesses due to a MRSA infection.
- Not only was this happening in the United States, but throughout other parts of the
world, other communities were experiencing basically the same phenomenon
of community-acquired MRSA infections.
So, why in the world did this happen? Well, that'sa great question and
honestly I wish I could tell ya.
It's probably like most things, a variety of several factors, but obviously
critical amongst that has got to be the overuse of antibiotics.
And while there’s no commercially available vaccine for staph aureus, there is
some encouraging progress with medical advances.
- One of the key elements that we're just beginning to understand
is the role of the host in causing and perpetuating staph infections.
The interplay between the bacteria and the host immunity is complex.
Ultimately, because staph aureus is so common, there are three main takeaways.
These are: prevention – washing your hands at home and in medical environments;
recognizing the symptoms early: boils, abscesses, and anything red or swollen;
and seeing your healthcare provider as soon as you see signs or feel ill.
- We understand now that there are things that we can do to help patients in the hospital
have a dramatically lower rate of developing staph infections.
So for example, daily chlorhexidine baths when they're in the Intensive Care Units.
While there have been setbacks in terms of new epidemiology, new outbreaks, the opioid crisis...
there's a lot of reason to have a good deal of optimism as well,
in terms of new drugs and better understanding.