Document Type

Dissertation - Open Access

Award Date


Degree Name

Master of Science (MS)

Department / School

Biology and Microbiology

First Advisor

Paul R. Middaugh


For many years, the role of anerobic bacteria in human disease was considered important only in such clostridial diseases as gas gangrene, botulism and tetanus. In the last 10 years, however, the development of new methods to isolate and identify anaerobic bacteria has established the pathogenic role of non-sporeforming anerobic bacteria in a wide variety of clinical infections in humans. Bacteroides fragilis is now known to account for approximately one fourth of all anerobic bacteria isolated from human clinical specimens. Recent advances in anaerobic bacteriology likewise have established that anaerobic bacteria are found as normal flora on the skin and all mucous membrane surfaces. Since almost all anaerobic bacterial infections originate endogenously, it is important to know the specific types of anaerobic bacteria present as normal flora at various sites on and in the human body. This enables one to predetermine which anaerobic bacteria may be involved in a particular infection and whether or not a particular isolate is significant. For example, the normal oral cavity of humans is mainly composed of Fusobacterium nucleatum, Bacteroids melaninogenicius, streptococci, peptostreptococci, lactobacilli, eubacteria and bifidobacterial. Under certain conditions predisposing to aspiration, anaerobic bacteria from the oral cavity can be carried into the lung. If the proper conditions exist in the lung (tissue necrosis from trauma, surgery, aerobic and facultative bacterial infection), anerobic bacteria can establish an infection such as a lung abscess. With the exception of clostridia, little information is known about the normal flora of animals or the identity of anerobic bacteria involved in nonspecific infections in animals. In contrast to human medicine, nonspecific infections such as anaerobic pleuropulmonary infections have been relatively ignored in veterinary medicine. Thus, the purpose of this research is to determine the relative incidence and species of anerobic bacteria present in bovine lung abscesses and to speculate on what role normal flora play in this type of infection. Since anaerobic bacteria have not been isolated to any great degree from animal infections, the susceptibility patterns of anaerobic bacteria isolated from human infections have been used by the veterinarian as a guide for antibiotic therapy in the treatment anerobic infections in animals. This practice is questionable because the antibiotic susceptibility of anerobic bacteria isolated from animals may not be identical to that demonstrated in man. Therefore, the second objective of this study is to provide information on the antibiotic susceptibility of anaerobic bacteria isolated from bovine lung abscesses. For the purposes of simplicity, obligately anaerobic bacteria, unless stated as such, will be referred to in this text as anaerobic bacteria or anaerobes.

Library of Congress Subject Headings

Cattle -- Diseases
Lungs -- Abcess
Anaerobic bacteria,/p>



Number of Pages



South Dakota State University