MDS PREP
In the context of tetanus, which statement is INCORRECT?
1) The primary antibody response is dominated by IgM.
2) The secondary antibody response is dominated by IgG.
3) Passive immunization is achieved through injection of tetanus antitoxin.
4) Adoptive immunization involves transfer of tetanus toxoid.
General Microbiology Answer: 4
Adoptive immunization involves the transfer of readymade immune cells, such as antibodies, from a donor to a recipient. Tetanus immunization is typically achieved through active immunization with the tetanus toxoid, which induces the body to produce its own antibodies against the tetanus toxin. Passive immunization, on the other hand, is achieved by injecting tetanus antitoxin, which provides immediate but temporary protection by neutralizing the toxin in the recipients body. The statement is incorrect because tetanus toxoid is used for active immunization, not adoptive immunization.
Which of the following is NOT a causative agent of dentoalveolar abscess?
1) Prevotella intermedia
2) P. melaninogenicus
3) Porphyromonas gingivalis
4) Fusobacterium nucleatum
General Microbiology Answer: 2Prevotella intermedia and P. melaninogenicus (now known as Aggregatibacter actinomycetemcomitans) are both anaerobic bacteria that can be found in the oral cavity and are involved in the pathogenesis of periodontal diseases, including dentoalveolar abscesses. Fusobacterium nucleatum is another anaerobic bacterium commonly found in dental plaque and is associated with various oral infections, including dentoalveolar abscesses.
Which of the following describes the colony morphology of Bacillus anthracis on an agar plate?
1) Smooth and shiny
2) Irregularly round with a frosted glass appearance
3) Small and translucent
4) Large and mucoid
Bacillus anthracis colonies on an agar plate typically appear irregularly round with a frosted glass appearance.
What is the typical color of Salmonella colonies on MacConkey agar, except for Sh. Sonnei?
1) Colorless
2) Pink
3) Red
4) Yellow
General Microbiology Answer: 1Salmonella species, excluding Shigella sonnei, which is lactose non-fermenting, will ferment lactose in MacConkey agar, turning the colonies pink due to the formation of acidic end-products
What is the primary clinical significance of a deficiency in C5 to C8 components of the complement system?
1) Hereditary angioneurotic edema
2) Recurrent pyogenic infections
3) Systemic lupus erythematosus
4) Neisserial infections
Recurrent pyogenic infections are associated with a deficiency in C5 to C8 components of the complement system.
What is the typical finding of eosinophils in amoebic dysentery?
1) Abundant
2) Few
3) Absent
4) Numerous
General Microbiology Answer: 3Amoebic dysentery is not typically associated with a significant eosinophilic response. Eosinophils are a type of white blood cell that is often involved in allergic reactions and parasitic infections, but their presence is usually minimal in the context of amoebic infections. The inflammatory response in amoebic dysentery is mainly composed of neutrophils and macrophages.
Which of the following is NOT a type of C1. Perfringens that can cause food poisoning?
1) C1. Perfringens type A
2) C1. Perfringens type B
3) C1. Perfringens type C
4) C1. Perfringens type D
General Microbiology Answer: 4
C1. Perfringens types A, B, and C are capable of producing toxins that cause food poisoning. Type D, however, is not associated with foodborne illness. It is primarily involved in diseases such as gas gangrene and other infections due to the production of different types of toxins.
What is the role of the Vi antigen in the pathogenesis of typhoid fever?
1) It aids in colonization of the intestinal mucosa.
2) It confers resistance to antibiotics.
3) It is involved in the production of toxins.
4) It allows the bacteria to evade the host's immune response by inhibiting phagocytosis.
General Microbiology Answer: 4The role of the Vi antigen in the pathogenesis of typhoid fever is it allows the bacteria to evade the hosts immune response by inhibiting phagocytosis: The Vi antigen is a polysaccharide capsule found in some strains of S. typhi that helps the bacteria avoid phagocytosis by host immune cells. This contributes to the bacterias ability to survive and proliferate within the human body.