Staphylococcus hominis is a common bacterium found on human skin. While usually harmless, it can lead to infections under certain conditions.
Understanding Staphylococcus hominis
Staphylococcus hominis is classified as a Gram-positive bacterium, appearing as spherical cells arranged in clusters. It belongs to the group of coagulase-negative staphylococci (CoNS), which lack the coagulase enzyme found in more virulent species like Staphylococcus aureus.
This bacterium primarily colonizes human skin, particularly in areas rich in apocrine glands such as the axillae and pubic regions. It constitutes a notable portion of the skin’s staphylococcal population, contributing to the natural microbiome. While typically harmlessly residing on the skin, its presence can sometimes contribute to body odor due to thioalcohol compounds.
When Staphylococcus hominis Causes Infection
Staphylococcus hominis is an opportunistic pathogen, typically causing infections in individuals with weakened immune systems or when it gains access to normally sterile body sites. Factors such as hospitalization, medical devices, and immunosuppression significantly increase infection risk.
Medical devices like central venous catheters, prosthetic joints, and pacemakers provide surfaces for bacterial attachment and colonization. Immunosuppression, whether from chemotherapy, HIV, or other predisposing illnesses, also makes individuals more susceptible. Premature infants are particularly vulnerable to S. hominis infections.
Infections include bloodstream infections, often associated with indwelling medical devices. It can also infect prosthetic devices like artificial heart valves and joint implants. Less frequent than S. aureus, S. hominis can also cause skin and soft tissue infections, especially in patients with prosthetic material. Less commonly, it has been implicated in urinary tract infections.
Biofilm formation is a key mechanism for S. hominis persistence on medical devices. Biofilms are communities of bacteria encased in a self-produced matrix, allowing adherence to surfaces and protection from antibiotics and the host immune system. This ability makes device-related infections challenging to treat effectively.
Diagnosis and Treatment
Diagnosing an Staphylococcus hominis infection typically involves culturing samples from the suspected site of infection, such as blood, wound exudate, or catheter tips. It is important for laboratories to distinguish between a true infection and mere contamination, especially when bacteria are isolated from blood cultures, given its common presence on skin. Laboratory identification methods include biochemical tests and mass spectrometry to confirm the species.
Treatment primarily relies on antibiotics, guided by the isolated strain’s susceptibility. Common classes of antibiotics include vancomycin, linezolid, and daptomycin for methicillin-resistant strains. For methicillin-susceptible strains, beta-lactam antibiotics like cephalosporins may be effective.
The emergence of methicillin-resistant S. hominis (MRSH) and multidrug-resistant strains poses a challenge to treatment, requiring careful antibiotic selection based on resistance profiles. For medical device-related infections, removal of the infected device is necessary. The duration of antibiotic treatment varies depending on the type and severity of the infection.
Prevention Strategies
Preventing Staphylococcus hominis infections involves a combination of practices in healthcare and daily life. In healthcare environments, strict adherence to hand hygiene protocols by healthcare workers reduces microorganism spread. Aseptic techniques are used during medical device insertion and maintenance, such as catheters and intravenous lines, to prevent bacterial introduction.
Proper skin antisepsis before medical procedures helps minimize infection risk. Removing unnecessary medical devices when no longer needed decreases opportunities for bacterial colonization. For the general public, maintaining good personal hygiene, including regular handwashing, is a fundamental preventative measure. Prompt and proper care of wounds helps prevent breaches in the skin barrier. Individuals with compromised immune systems should be aware of these measures.