The epidemiology of Staphylococcus hominis: 

Distribution: Staphylococcus hominis is widely distributed and can be found on healthy individuals’ skin and mucous membranes. It is a member of the human microbiota, particularly in the axilla, groin, and perineal areas. 

Colonization and Transmission: Staphylococcus hominis can colonize the skin and mucous membranes through direct contact with contaminated surfaces or through person-to-person transmission. It can also be acquired from healthcare settings, especially in individuals with weakened immune systems. 

Opportunistic Infections: Staphylococcus hominis can cause various opportunistic infections, especially for those with weakened immune systems, such as those with underlying medical conditions, surgical patients, or indwelling medical devices like catheters. Common infections include: 

• Bloodstream infections (bacteremia). 
• Urinary tract infections. 
• Infections at surgical sites. 
• Infections linked to central venous catheters. 

Antibiotic Resistance: Like other Staphylococcus species, Staphylococcus hominis could develop antibiotic resistance. It has been associated with antibiotic resistance, including methicillin-resistant Staphylococcus hominis (MRSH). It can complicate treatment and increase the risk of healthcare-associated infections. 

Hospital-Associated Infections: Staphylococcus hominis is often implicated in healthcare-associated infections, particularly in intensive care units (ICUs) and other healthcare settings. These infections can be challenging to treat due to antibiotic-resistant strains and the potential for the organism to form biofilms on medical devices. 

Staphylococcus hominis is a species of bacteria that belongs to the genus Staphylococcus and the family Staphylococcaceae. Here is the taxonomical classification of Staphylococcus hominis: 

Kingdom: Bacteria 

Phylum: Bacillota 

Class: Bacilli 

Order: Bacillales 

Family: Staphylococcaceae 

Genus: Staphylococcus 

Species: S. hominis 

the structure of Staphylococcus hominis: 

Cell Wall: Like other Gram-positive bacteria, Staphylococcus hominis has a thick cell wall composed of peptidoglycan. The peptidoglycan layer provides structural support and protection for the bacterium. 

Cell Membrane: Beneath the cell wall is a plasma membrane separating the bacterium’s internal components from the external environment. It controls how molecules enter and exit the body of the cell. 

Capsule: Some strains of Staphylococcus hominis may possess a polysaccharide capsule outside the cell wall. The capsule helps the bacterium evade the host immune system by impairing phagocytosis and can contribute to virulence. 

Cytoplasm: Inside the cell membrane, Staphylococcus hominis contains cytoplasm, which houses various cellular components such as DNA, ribosomes, enzymes, and other proteins necessary for cellular functions. 

Surface Structures: Staphylococcus hominis has numerous surface structures, including proteins and polysaccharides, which play essential roles in adhesion, colonization, and immune evasion. These structures can vary among different strains. 

The antigenic types of S. hominis have yet to be well studied, but some studies have reported the presence of antimicrobial peptides and antibiotic-resistance genes in this species. These factors may contribute to the pathogenicity and virulence of S. hominis in certain conditions. Staphylococcus hominis can be divided into two subspecies: S. hominis subsp. hominis & S. hominis subsp. novobiosepticus. These subspecies can be identified by their novobiocin susceptibility and their habitat. S. hominis subsp. hominis is susceptible to novobiocin, whereas S. hominis subsp. novobiosepticus is not susceptible to novobiocin.

Besides novobiocin susceptibility, these subspecies can also be distinguished by their SDS-PAGE or MALDI-TOF MS profiles. These methods can detect differences in the two subspecies’ protein patterns or mass spectra. Another way to identify S. hominis subspecies is by their trehalose fermentation ability. Unlike S. epidermidis, S. hominis produces acid from trehalose, so the two tests together identify the species. However, some strains of S. hominis subsp. novobiosepticus can also ferment trehalose, considered atypical phenotypic results for this subspecies. 

The pathogenesis of S. hominis infection is not fully understood, but it may involve multiple factors, such as: 

• Adhesion and invasion of epithelial cells. S. hominis can bind to the surface of host cells and then penetrate the cytoplasm, where it can evade the immune system and cause damage. 
• Antibiotic and antimicrobial peptide resistance. S. hominis can acquire genes that confer resistance to various antibiotics, such as penicillin, tetracycline, and novobiocin. It can also produce enzymes that degrade antimicrobial peptides produced by the host. 
• Production of extracellular toxins. S. hominis can secrete toxins that can cause inflammation, cell death, tissue damage, and food poisoning. 
• Biofilm formation. S. hominis can form biofilms on medical devices or host tissues, protecting the bacteria from antibiotics and immune cells and facilitating chronic infections. 

The host defenses of S. hominis infection may include the following: 

• Neutrophils. These are the most abundant white blood cells that can phagocytose and kill S. hominis and other bacteria. They also release reactive oxygen species and antimicrobial peptides that can damage the bacterial cell wall. 
• Complement system. This part of the innate immune system can recognize and opsonize S. hominis and other bacteria, facilitating their phagocytosis by neutrophils and macrophages. It can also form membrane attack complexes that can lyse the bacterial cells. 
• Antibodies. These are produced by B cells as part of the adaptive immune system and can bind to S. hominis and other bacteria, neutralizing their toxins and enhancing their opsonization and phagocytosis. 
• Antimicrobial peptides. These small molecules produced by various host cells, such as keratinocytes, sebocytes, and sweat glands, can inhibit the growth of S. hominis and other bacteria on the skin surface. Some strains of S. hominis can also produce antimicrobial peptides, such as hominin, that can protect the host from S. aureus infection. 

The symptoms of the location and severity of an infection with S. hominis. Some of the possible symptoms are: 

• Skin infections include boils, impetigo, cellulitis, or scalded skin syndrome. These may cause redness, swelling, pain, pus, or blisters on the skin. 
• Food poisoning if the bacteria contaminate food and produce toxins. It may cause nausea, vomiting, diarrhea, dehydration, and low blood pressure. 
• Bacteremia, if the bacteria enter the bloodstream. It may cause fever, chills, low blood pressure, and organ damage. 
• Endocarditis, if the bacteria infect the inner lining of the heart. It may cause fever, chills, heart murmur, fatigue, and shortness of breath. 
• Septic arthritis if the bacteria infect the joints. It may cause pain, swelling, redness, and reduced movement in the affected joint. 

the following tests to identify a staph infection: 

• Conduct a medical examination. Your doctor will check for any skin lesions or irritated areas while doing the examination. Any further symptoms might be reviewed by your doctor. 
• Gather a sample for analysis. Staph infections are often diagnosed by looking for indications of the bacteria in the patient’s blood, urine, skin, contaminated material, or nasal secretions. 
• Recommend other tests. Depending on your signs and the outcomes of your tests, your doctor may order other tests to check for complications or rule out other conditions. 

Some specific tests that can help identify S. hominis are: 

• Test for Novobiocin susceptibility.

• Test for deferoxamine sensitivity. 

• Trehalose fermentation experiment. 

Some of the ways to prevent Staphylococcus hominis infection are: 

• Use water and soap to wash your hands often. 
• Clean and cover any wounds with a sterile, dry bandage until they heal. 
• Keep personal goods like towels, razors, and other objects in personal clothing that may encounter infected skin. 
• Do not touch or squeeze boils or other skin infections. 
• Whenever you notice any indications of a severe infection, such as fever, chills, or pus. 

• Staphylococcus hominis- An Overview – Microbe Notes 
• Staphylococcus hominis – microbewiki (kenyon.edu)