Chapter 14
A. (3).
B. Isolation of pure culture of the pathogen, its identification and determination of its susceptibility to antibiotics.
C. A specific feature of serology in virology is the paired sera test. The first serum is sampled from the patient during the acute period at the beginning of the disease, stored at a temperature of +4-8 °С, and the second serum is sampled in 10-14 days. The sera are tested simultaneously. Seroconversion, i.e. an increase in the antibody titer in the second serum as compared to the first one, is indicative of disease. At least four-fold seronversion is diagnostic. For this reason, the result obtained in a test with only one serum cannot be considered reliable.
D. Maximum security laboratories.
Chapter 15 (15.1)
A. Compared to other gram-negative bacteria gonococci do not have typical LPS with a long O-specific polysaccharide chain, but they have a short glycolipid, which is called lipooligosaccharide (LOS). The structure of gono-coccal LOS is similar to that of the glycosphingolipid of the human cytoplasmic membrane, so thanks to the presence of a structure similar to the human cell on the microbe's surface the microbe is disguised thus avoiding immune recognition.
B. S. saprophyticus.
C. The immunity against S. pyogenes is type-specific, and there are only 80 serovars known. Scarlet fever is caused by S. pyogenes of group A, producing the protein erythrogenic toxin, whose synthesis is mediated by the converting bacteriophage. For this reason strong antitoxic immunity is developed during scarlet fever.
Chapter 15 (15.2)
A. (1, 2, 3). B. (3). C. (2, 4). D. (4). E. (2).
F. When entering the small intestine the pathogens of typhoid and paratyphoid fever invade the mucous membrane with effector proteins ТTSS-1, forming the primary focus of infection in Peyer's patches. It should be noted that the osmotic pressure in the submucous membrane is lower than in the intestinal lumen below. This supports intensive synthesis of Vi-antigen, which