Professor Dave again, let’s talk about staph infections.
You’ve probably heard some talk about “superbugs” in the media, but what’s really going on?
First, let’s talk about Staphylococcus aureus, which is commonly known as “staph.”
These bacteria are typically harmless and commonly found on the skin of many healthy people.
However, in certain cases, as we discussed earlier when we talked about opportunistic
pathogens, these bacteria can cause serious, or even deadly infections.
Let’s get some more information on these little critters.
In the past few decades in particular, a more dangerous form of staph has emerged, which
is called methicillin-resistant Staphylococcus aureus, or MRSA.
MRSA is resistant to the entire class of beta-lactam antibiotics, which includes methicillin, penicillin,
amoxicillin, and oxacillin, all antibiotics you’ve likely heard of and almost certainly
taken in your lifetime.
The different types of MRSA infections are split into categories based on where they’re acquired.
For instance, healthcare-acquired MRSA (or HA-MRSA) has been documented since the 1960s,
particularly in hospitals and other healthcare facilities.
Patients with weakened immune systems, recent surgery, or those with medical devices implanted
are at higher risk for HA-MRSA, and the incidence of these infections has been increasing steadily
over time.
A second, and more alarming type of MRSA infection emerged in the 1990s, called community-acquired
MRSA, or CA-MRSA.
The points of origin for these infections can be more difficult to identify, but are
thought to be common in childcare settings, long-term care facilities, athletic settings,
or in individuals sharing towels or other objects.
These infections often first appear as simple skin infections, but can progress into life-threatening illness.
So how do these strains develop?
And why do they develop?
Zooming into the microscopic level, Staphylococcus aureus is the most virulent and best-known
member of the group of gram-positive cocci, Staphylococcus.
These bacteria have a capsule that protects their outermost layer, and they produce a
slime layer that helps them bind to things like catheters, prosthetic valves or joints,
or grafts.
Staph aureus also produce an impressive number of toxins and enzymes that help them trigger
immune responses and destroy healthy tissue, truly wreaking havoc in the body.
When we first started using penicillin to treat Staph aureus infections in 1941, over
90% of staphylococcal isolates were susceptible to the drug.
However, resistance to penicillin developed quickly, partially due to the natural evolution
of the bacteria, but accelerated by overuse and inappropriate use of these drugs by humans.
Many of these bacteria can produce what’s called penicillinase, or beta-lactamase, which
easily renders the antibiotic ineffective.
Even worse, these beta-lactamase enzymes are commonly found on transmissible plasmids,
which can be traded between bacteria essentially like trading cards.
The thing is, bacteria are inherently driven to evolve, and as humans, we’re pretty good
at helping them do that.
The incidence of disease caused by MRSA has increased significantly worldwide, and the
bacteria continue to evolve and take on new traits.
For instance, in 2002, scientists found the first Staph strains to be resistant to vancomycin,
which is one of the few last-resort treatments against MRSA.
Vancomycin-resistant staph strains, or VRSA, are rare for the time being, but health officials
fear incidence of these strains will rise.
To reduce your risk of MRSA infection, CDC recommends always maintaining good hand and
body hygiene, keeping wounds clean and covered, avoiding sharing personal items such as towels,
and checking in with your doctor if you think you might have an infection.
And in general, always make sure to only take antibiotics when you truly need them, and
when you do, take them exactly as instructed.
With some smarts and some luck, we can get rid of these little guys within the century.