Staphylococcus Species

staphylococcus speciesStaphylococcus species are Gram Positive cocci (spherical) bacteria belonging to the Micrococcaceae family, which also includes Micrococcus and Kocuria.

Members of this family inhabit the skin and mucous membranes of mammals and birds. Staphylococci can be divided into two major groups depending on their production of coagulase.  Coagulase-negative staphylococci (CNS) include S. epidermidis, which is the most frequently isolated staphylococcal species colonizing the human body surface.

In many cases, these organisms are nonpathogenic colonizers but a few are important human pathogens, such as S. epidermidis, S. haemolyticus, S. lugdunensis, and S. saprophyticus.  CNS have been increasingly recognized as health-care associated pathogens, particularly in patients with indwelling medical devices.

These organisms can be commonly found in cleanroom environments, particularly in the air.  This is consistent with personnel being the primary source of these organisms through shedding of skin cells which then become air-borne.

Coagulase positive staphylococci are known human pathogens. Transmission of these organisms occurs through direct contact with colonized or infected persons or through indirect contact with contaminated objects.  S. aureus is the most common species in this group; additional species include S. lugdunensis and S. schleiferi.  Coagulase-positive staphylococci are considered action organisms under current USP 797 guidelines.


Methicillin-resistant Staphylococcus aureus (MRSA) is a multidrug-resistant bacterium that can cause serious, even life-threatening infections. MRSA is spread by direct human contact and by touching contaminated surfaces or objects. About 2% of the population are carriers of MRSA bacteria, although the majority are not infected.

Because staphylococcal infections, including MRSA, are opportunistic, such infections are more common among people who are in hospitals, nursing homes, and other health care facilities where individuals are likely to have weakened immune systems.  Infections can appear at the site of surgical wounds or around invasive devices, like catheters and implanted feeding tubes.

The identification of a S. aureus strain as MRSA requires additional phenotypic or genotypic testing.

Environmental Testing

At U.S. Micro Solutions, our microbiology laboratory is a licensed, accredited source for thorough and accurate environmental testing, including USP 797, Legionella, indoor air quality, healthcare & medical device, water analysis, and identification of specific pathogens. Visit our Laboratory Services page to learn more.

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