STAPHYLOCOCCI 57 



growth covers the surface in several days and is white, golden or lemon-colored, 

 according to the staphylococcus present. 



Indol is not produced in 48 to 72 hours. 



Media Containing dextrose, lactose, saccharose, maltose, mannite or glycerin 

 may not be acidulated, usually they are, but gas is not formed. 



Spore Formation. Staphylococci do not form spores. 



Resistance. Staphylococci remain alive on culture media for months. 

 Deprived of moisture they remain for several weeks or months. Repeated 

 freezing does not kill them. When surrounded by or contained in albuminous 

 matter they are especially resistant. Marked variations in resistance to 

 chemical and thermal germicides are shown by different cultures; 1:1000 

 solutions of bichloride of mercury kills them in 10 minutes; i : 100 carbolic acid 

 kills in from ^ to 2 hours. In a moist state they are usually killed by an ex- 

 posure of J^-hour to 6oC.; some strains resist 8oC. for i hour. Boiling kills 

 them almost instantly. In a dry state, 9OC. to iooC. for % hour is required 

 to kill them. 



Toxin. Staphylococci produce an intracellular toxin destructive to both red 

 and white blood cells. 



Agglutinins. Specific for the staphylococcus have been produced experi- 

 mentally, but cannot be regularly detected in patients infected with Staphy- 

 lococci. 



PATHOGENESIS 



Staphylococci vary in virulence, some are very virulent and others are in- 

 capable of producing disease. The majority of infections following wounds and 

 operations and most of the suppurative processes, boils and abscesses are caused 

 by Staphylococci, usually staphylococcus aureus. No portion of the body is 

 invulnerable to them. They are sometimes the offending organisms in rhinitis, 

 otitis, coryza, pharyngitis, bronchitis, pneumonia, pleurisy, endocarditis, syno- 

 vitis, enteritis, nephritis, cystitis, urethritis and meningitis. Staphylococci 

 infections may be localized or widespread. Entering a wound they may lodge 

 in adjacent tissue, injure or destroy it, but progress no further, as in single 

 abscess formation. They may enter through a wound, invade the lymph glands, 

 travel through the lymph vessels and lodge in various tissues and organs produc- 

 ing inflammation or suppuration at each focus. Likewise, they may enter the 

 blood stream and be disseminated throughout the body or lodge in one or 

 several organs. 



Lower animals seem less susceptible to staphylococcus infection than man, 

 but they are not immune. 



Cultures injected into guinea-pigs, rats, rabbits, cats or dogs act as they do 

 in man. Of the animals mentioned rabbits are most susceptible to Staphylococci. 



DIAGNOSIS 



Upon inflamed surfaces and in pus produced by Staphylococci the organisms 

 are abundant. A loopful of pus, or scrapings from an inflamed surface, ob- 

 tained with a cotton swab, when smeared on a slide, dried and stained, will 



