Microbiology Lab Quiz # 4 - Nov 21 2008

Aerobic organisms require oxygen for growth and metabolism, while anaerobic organisms can survive without oxygen. The specificity in identifying these organisms helps in understanding their metabolic characteristics.

Strict anaerobes are organisms that cannot survive in the presence of oxygen. Clostridium novyi is an example of a strict anaerobe as it thrives in anaerobic environments. On the other hand, Escherichia coli, Staphylococcus aureus, and Pseudomonas aeruginosa are examples of facultative anaerobes, meaning they can survive in both aerobic and anaerobic conditions.

Aerotolerant anaerobes are microorganisms that can survive and grow in environments with reduced oxygen levels, although their growth is limited. They do not require oxygen for metabolism, but they are not harmed by its presence either. P. acnes is an example of an aerotolerant anaerobe.

A microaerophile is an organism that requires reduced concentrations of oxygen for its growth, but is not capable of tolerating the normal atmospheric oxygen levels. Campylobacter jejuni is a common example of a microaerophile.

The correct answer includes diseases caused by anaerobic bacteria, while the incorrect answers are caused by viruses.

The correct answer provides examples specifically related to endogenous infections by anaerobic bacteria, while the incorrect answers do not align with this criteria.

The correct temperature for storage is RT because refrigeration can lead to oxygenation which can result in the loss of recovery of anaerobes in samples suspected of anaerobic infection.

The correct answer emphasizes the time constraint of planting the collected sample within 2 hours to ensure recovery of anaerobic bacteria. The incorrect answers provide alternative statements that do not align with the specific 2 hr lab rule for anaerobic bacteria.

Anaerobic infections, especially abscesses, are typically associated with foul-smelling exudate, gas production, presence of sulphur granules, and being located near mucosal surfaces. The incorrect answers provide attributes that are not commonly seen in anaerobic infections.

Anaerobes are susceptible to metronidazole because the drug targets their anaerobic metabolism, making them sensitive to its effects.

BRU is enriched with Na bisulfate, hemin, and vitamin K to enhance its nutritional value, while the incorrect answers do not align with the actual ingredients added for enrichment.

Clostridium perfringens is known to display classic double zone hemolysis on blood agar plates, making it a useful identifying characteristic in microbiology. Staphylococcus aureus, Escherichia coli, and Enterococcus faecalis do not typically exhibit this particular hemolytic pattern.

Prevotella and Porphyromonas are anaerobic bacteria commonly associated with infections in the oral cavity. They produce pigmented colonies that are brown to black with a foul odor on BRU media, making them distinguishable from other bacteria.

Bacteroides ureolyticus is known to pit the agar of BRU due to its unique growth and enzymatic properties. Escherichia coli, Staphylococcus aureus, and Pseudomonas aeruginosa are not typically associated with pitting the agar of BRU.

The correct answer is Bacteroides spp. Gram-negative organisms that grow on CNA (Colistin-Nalidixic Acid) or PEA (Phenylethyl Alcohol) agar under anaerobic conditions are likely to be Bacteroides spp., which are commonly found in the microbiota of the gastrointestinal tract.

Gram-positive organisms that are alpha-hemolytic and grow on CNA or PEA agar under anaerobic conditions are most likely to belong to the genus Fusobacterium. Streptococcus and Staphylococcus are primarily found in different conditions and Escherichia is a gram-negative organism.

Bacteroides spp. are anaerobic bacteria commonly found in the human gut microbiota, which thrive in low oxygen environments like the LKV plate under ANO2 conditions. Escherichia coli and Streptococcus pyogenes are facultative anaerobes that can grow in a variety of conditions, while Pseudomonas aeruginosa is an obligate aerobe that prefers oxygen-rich environments.

The correct answer is Bacteroides spp. because the 'B' in BBE stands for Bacteroides, indicating that organisms growing on this medium are likely to belong to the Bacteroides genus.

Bacteroides fragilis is known to grow on BBE (Bacteroides Bile Esculin), and also hydrolyzes escullin which results in a positive Esc test. The other three species mentioned do not exhibit both these characteristics.

The reverse camp test helps confirm the presence of Clostridium perfringens by demonstrating an inhibitory effect on the beta-hemolysin production of Staphylococcus aureus.

The correct answer is 20% oxgall; gentamicin; esculin for differential. Oxgall is also known as bile. The combination of oxgall, gentamicin, and esculin help make the BBE media selective and differential for certain types of bacteria.

LKV plates contain Kanamycin and vancomycin which inhibit the growth of facultative gram negative bacteria. The incorrect answers given contain different antibiotics that do not match what is actually present in LKV plates nor the type of organisms inhibited by them.

PEA media, or phenylethyl alcohol agar, is a selective agar used for the isolation of Gram-positive bacteria. It inhibits swarmers like Proteus, allowing other bacteria to grow on the media.

CCFA media stands for cycloserine cefoxitin fructose agar and it is used to isolate Clostridium difficile, not Clostridium perfringens, Listeria monocytogenes, or any other organisms listed in the incorrect answers.

THIO stands for thioglycollate, which is a substance commonly used in microbiology for cultivating anaerobic organisms.

EYA stands for Egg Yolk Agar, which is a microbiological culture medium used for various purposes in laboratories. The correct ingredients in EYA are egg yolk, hemin, and vitamin K.

The correct differential tests incorporated into EYA are Lecithinase & Lipase. Amylase, Protease, and Catalase are not the specific differential tests used in EYA.