Cultivation of Anaerobic Bacteria Culture and Its Application

  • Anaerobic bacterial culture is a method used to grow anaerobic bacteria from clinical specimens. Obligate anaerobes are bacteria that can only survive in the absence of oxygen. When exposed to the atmosphere for 10 minutes, obligate anaerobes are destroyed. Some anaerobic bacteria tolerate small amounts of oxygen. Facultative anaerobes are organisms that can grow in aerobic or anaerobic conditions. Performing anaerobic culture specimen acquisition methods and culture procedures to ensure that organisms are protected from oxygen.


    Performing anaerobic bacterial culture to identify bacteria that grow only under hypoxic conditions and may cause human infections. If neglected or killed due to exposure to oxygen, anaerobic infection can lead to serious consequences such as amputation, organ failure, sepsis, meningitis, and death. Culture is needed to correctly identify anaerobic pathogens and carry out effective antibiotic treatment.


    It is essential for healthcare providers to obtain culture samples through aseptic technique. Anaerobic bacteria are commonly found in mucous membranes and other areas, such as the vagina and oral cavity. Therefore, specimens that may be contaminated with these microorganisms should not be cultured (for example, throat or vagina swabs). If infection is suspected, certain types of specimens should always be cultured with anaerobes. These include abscesses, bites, blood, cerebrospinal fluid and oozing body fluids, deep wounds and necrotic tissue. The specimen must be free of oxygen during collection and transportation, and must be transported to the laboratory immediately. Members of the healthcare team performing the collection should follow general precautions to prevent the spread of blood-borne pathogens.


    The key to effective anaerobic bacterial culture includes collecting non-contaminated specimens and protecting them from oxygen exposure. Anaerobic cultures should be obtained from a suitable site, and health care professionals should not use bacterial contamination samples from adjacent skin, mucous membranes, or tissues. Swabs should be avoided when collecting specimens for anaerobic culture, because cotton fibers may be harmful to anaerobic bacteria. A sterile syringe can be used to aspirate the abscess or fluid, and then cover it tightly to prevent air from entering.


    Tissue samples should be placed in a degassed bag and sealed, or placed in a deflated screw cap vial that may contain anaerobic pre-reduced medium and capped tightly. The specimen should be inoculated as soon as possible on a medium that has been prepared as a pre-reduced anaerobic sterile medium (PRAS). Alternatively, a medium that contains a reducing agent (such as dithiothreitol or palladium chloride) and has been stored in an anaerobic chamber for one day can be used.


    Isolated organisms are always subcultured, and pure cultures are tested to identify the organism. The identification of anaerobic bacteria is very complicated, and laboratories may use different identification systems. Partial recognition is usually the goal. For example, 6 species of Bacteroides may be identified as Bacteroides fragilis groupings rather than individually identified. Organisms are identified by their community and microscopic morphology, growth on selective media, oxygen tolerance, and biochemical characteristics. These include sugar fermentation, bile solubility, esculin, starch and gelatin hydrolysis, casein and gelatin digestion, catalase, lipase, lecithinase and indole production, nitrate reduction, volatility determined by gas chromatography Fatty acids and sensitivity to antibiotics. The antibiotic sensitivity curve is determined by the microtubule broth dilution method. Many anaerobic bacteria are resistant to penicillin, and some are resistant to common antibiotics such as clindamycin.


    Health care providers should pay special attention to collecting non-contaminated specimens. All procedures must be performed under sterile conditions. Health care professionals collecting specimens should be prepared to collect two samples, one for anaerobic culture and one for aerobic culture, because it is not clear whether the pathogen can grow under aerobic or anaerobic conditions. In addition, health care professionals should record any antibiotics the patient is currently taking and any medical conditions that may affect the growth of bacteria.


    About the Author

    Creative Bioarray is a global leading provider of quality services in research and development including cardiac & neuronal safety profiling and translational assays for the academia, pharmaceutical, and biotechnology industries. We offer an innovative, time-efficient, cost-effective and comprehensive range of preclinical R&D services specialized in but not limited to cardiovascular & neural system physiological/pathophysiological mechanisms with strong scientific support.