Twort discovered the action of bacteriophages on staphylococci bacteria. Bacteria that enter through the skin, such as streptococci and staphylococci, tend to predominate. Staphylococcus haemolyticus is a member of the coagulase-negative staphylococci (CoNS). Despite the macrolide component, it is effective against erythromycin-resistant staphylococci and strepcococci. In moist places on the body Corynebacteria together with Staphylococci dominate. Beta-hemolytic streptococci, pneumococci, staphylococci, and enterococci are usually susceptible to macrolides. It is used to differentiate micrococci and staphylococci. Typically, this includes alpha-hemolytic streptococci, staphylococci, and bacteroides groups. It is not active against beta-lactamase-producing bacteria, which include many strains of "Staphylococci". By 1927, Fleming had been investigating the properties of staphylococci. Common abbreviations for coagulase-negative staphylococci are CoNS, CNS, or CNST. This group is the only clade within the staphylococci to possess this gene. Propionibacteria and Staphylococci species were the main species in sebaceous areas. Naturally the cause is bacteria such as staphylococci that are present on the skin. Vertebral osteomyelitis is most commonly caused by staphylococci.