Spirochætes in the blood of a goat Get access G. Norman Hall, M.R.C.V.S. G. Norman Hall, M.R.C.V.S. Veterinary Pathologist, Veterinary Laboratory, Entebbe, Uganda Search for other works by this author on: Oxford Academic PubMed Google Scholar Transactions of The Royal Society of Tropical Medicine and Hygiene, Volume 21, Issue 5, 25 February 1928, Pages 423–425, https://doi.org/10.1016/S0035-9203(28)90075-9 Published: 25 February 1928
Aerobic Gram-positive and Gram-negative bacteria can be important pathogens in the immunocompromised host, especially in individuals who have compromised humoral immunity. Emphasis in this section will be placed on the most common bacteria that are associated with the immunocompromised host, although other aerobic bacteria will be discussed in certain sections for completeness. Aerobic bacteria are those that survive in the presence of oxygen, for example, in room air; they may grow in the laboratory under anaerobic conditions as well, but they prefer aerobic conditions. Some are obligate aerobes, such as Mycobacterium tuberculosis and Pseudomonas aeruginosa; others are facultative anaerobes, surviving with and without oxygen, such as Staphylococcus aureus and members of the Enterobacteriaceae (such as Escherichia coli and Salmonella spp.). Obligate anaerobes include Bacteroides fragilis and most Clostridium spp. Some anaerobes, such as Clostridium tertium, are termed aerotolerant anaerobes since their metabolism is anaerobic, but they can exist in the presence of oxygen. Lastly, there are microaerophilic bacteria, such as Campylobacter spp., which grow optimally in an environment in which the amount of oxygen is reduced but not eliminated.
ABSTRACT Aerobic Gram-positive and Gram-negative bacteria can be important pathogens in the immunocompromised host. These bacteria can be found in many environments, as part of the normal microbiota of the human host and animals, in soil and water, on plants, on fomites in the hospital, and on hospital equipment. This review provides information from relevant studies about what are the most common aerobic bacteria associated with patients who have cancer and/or are being treated for it, or who have other diseases which lead to immunodeficiencies, such as HIV, multiple myeloma, aplastic anemia, chronic diseases, and aging. A discussion of the appropriate laboratory tests needed for diagnosis of aerobic infections and information about antibiotics and susceptibility testing are also included.
The foregoing experiments conclusively show that a broth medium is quite unsuitable as a test culture medium to determine the vitality of anthrax spores in disinfection experiments, whereas agar is a suitable and delicate medium for the purpose, even when considerable traces of the disinfectant are carried over with the inoculation. The reason for this inefficiency of broth is not obvious. We thought that it might be due to the absence of bacillar forms in the sporing material, but the emulsion of spores heated to 80°C. for 15 minutes and then inoculated directly into broth gave good growths. Absence of oxygen might be another factor, but the results were the same when splinters of sterilised wood infected with anthrax spores were treated. The wood floated on the surface of the broth and so was subjected to a free supply of oxygen, yet no growths were obtained in broth when the splinters were soaked in the disinfectants, while good growths were obtained on agar. The control splinters gave good growths in broth. It may be that the anthrax spores are partially de-vitalised by the action of the disinfectant and that in this condition broth is a comparatively unsuitable culture medium for them. Prolonging the time of incubation of the broth cultures up to 10 or 14 days makes no difference. If a culture in broth shows no growth in 48 hours, a growth hardly ever appears with more prolonged incubation. Nor is this superiority of agar over broth as a culture medium confined to the emulsified disinfectants employed in these experiments, for similar results have been obtained with phenol, and with formaldehyde, the latter both in the fluid (formalin), and in the gaseous, conditions.
