Staphylococcus hominis

Staphylococcus hominis is a coagulase-negative member of the bacterial genus Staphylococcus, consisting of Gram-positive, spherical cells in clusters. It occurs very commonly as a harmless commensal on human and animal skin and is known for producing thioalcohol compounds that contribute to body odour. Like many other coagulase-negative staphylococci, S. hominis may occasionally cause infection in patients whose immune systems are compromised, for example by chemotherapy or predisposing illness. Colonies of S. hominis are small, usually 1–2 mm in diameter after 24 hours' incubation at 35 °C, and white or tan in colour. Occasionally, strains are resistant to novobiocin and may be confused with other resistant species (e.g. S. saprophyticus). It is one of only two species of Staphylococcus to display sensitivity to desferrioxamine, the other being S. epidermidis. Unlike S. epidermidis, S. hominis produces acid from trehalose, so the two tests together serve to identify the species. Numerous coagulase-negative staphylococci appear commonly on the skin of human. Of these species, S. epidermidis and S. hominis are the most abundant. While S. epidermidis tends to colonize the upper part of the body, S. hominis tends to colonize in areas with numerous apocrine glands, such as axillae and the pubic region. In a certain study, S. hominis was calculated to account for 22% of the total staphylococcal species recovered from individuals, second to S. epidermidis at 46%. S. hominis is the predominant species on the head, axillae, arms, and legs.S. hominis, as well as most other staphylococcal species common on the human skin, is able to produce acid aerobically from glucose, fructose, sucrose, trehalose, and glycerol. Some strains were also able to produce acid from turanose, lactose, galactose, melezitose, mannitol, and mannose. Most strains colonize on the skin for relatively short periods of time compared to other Staphylococcus species. They, on average, stay on the skin for only several weeks or months.The cell wall contains low amounts of teichoic acid and glutamic acid. The cell wall teichoic acid contains glycerol and glucosamine.S. hominis cells are Gram-positive cocci, usually 1.2 to 1.4 μm in diameter. They appear normally in tetrads and sometimes in pairs. Based on a total of 240 strains, all were resistant to lysozyme, some were slightly resistant to lysostaphin, 77% were susceptible to penicillin G, 97% to streptomycin, 93% to erythromycin, 64% to tetracycline, and 99% to novobiocin.