Which of the following pathogens satisfies all of Koch's postulates? ?
Show answer Hide answer
Answer: D. None of the above
Explanation
Koch's postulates require a pathogen to be isolated in pure culture on artificial cell-free media. Treponema pallidum and Mycobacterium leprae cannot be successfully cultivated on standard cell-free laboratory media. Consequently, these obligate pathogens do not strictly satisfy all of Koch's classic postulates. Robert Koch formulated criteria to establish a causal relationship between a specific microbe and a disease. Obligatory intracellular pathogens depend entirely on host cells for their metabolic survival and replication. Molecular diagnostics and animal models have largely supplemented traditional culture-based postulates in modern science.
Syphilis and leprosy were studied extensively despite the inability to culture their causative agents traditionally. Molecular adaptations like PCR allow researchers to confirm pathogen presence without requiring pure culture isolation. Understanding historical postulates highlights the evolution of modern medical microbiology and disease causation. Option A represents Treponema pallidum, which fails standard artificial culture requirements for Koch's rules. Option B represents Mycobacterium leprae, an unculturable organism that defies classic postulate verification. Option C represents Neisseria gonorrhoeae, which can be cultured on specialized media unlike strict obligates.
Related questions
Q1. Which of the following pairs are correctly matched ?
Show answer Hide answer
Answer: D. All of the above
Maternal antibody transfer, immune globulin injections, and active vaccination represent immunity types. Colostrum provides natural passive immunity by transferring maternal antibodies to nursing infants. Administration...
Q2. Which of the following immunizations is classified as a cell fraction-derived vaccine? ______________?
Show answer Hide answer
Answer: D. Hepatitis B
The Hepatitis B vaccine is manufactured using recombinant DNA technology to express purified surface antigens. This process isolates specific viral protein fractions rather than using whole inactivated or live viruses. P...
Q3. What is the standard concentration of agar used in preparing solid agar media? ___________________?
Show answer Hide answer
Answer: B. 2%
Standard nutrient agar media for routine bacteriological culture is prepared using an agar concentration of two percent. This concentration provides a firm solid surface that supports bacterial colony growth without melt...
Q4. Which of the following conditions does not typically progress to a chronic hepatitis stage ?
Show answer Hide answer
Answer: D. HEV
Hepatitis E virus typically causes acute self-limiting infections and lacks chronic states. Unlike other hepatitis viruses, HEV rarely establishes persistent long-term hepatic infections. Most immunocompetent individuals...
Q5. Viruses can be isolated from clinical samples via all of the following laboratory methods except_______________?
Show answer Hide answer
Answer: D. Chemically defined media
Viruses are obligate intracellular parasites that cannot replicate independently on nutrient broth or agar. Chemically defined media lack living host cells, making viral replication and isolation impossible. Attempting t...
Q6. Which human immunoglobulin has the highest mean serum concentration? _________________?
Show answer Hide answer
Answer: C. IgG
Immunoglobulin G is the predominant antibody class circulating in human serum at the highest mean concentration. IgG accounts for approximately seventy-five percent of total serum immunoglobulins in healthy adult humans....