Microbiology 2008 Flashcards
Organisms that utilize only the fermentative pathways in their metabolism are known as:
anaerobes
At which stage in the growth of a bacteria is there a slow loss of cells through death that is just balanced by the formation of new cells through growth and division.
lag phase
Bacteremic shock is triggered by
endotoxins
The toxic property of endotoxin lies in the
lipid A
Which of the following components of a bacterial cell wall is susceptible to lysozyme?
peptidoglycan
The primary difference between Gram positive and Gram negative bacteria lies in the
cell wall
Koch’s postulate states the following except
A. The organism must be isolated in pure culture. / B. It must produce the same disease when pure culture is inoculated into experimental animal. / C. The organism must be recovered in pure culture from the experimentally infected animals. / D. The disease must be reproduced in susceptible animals by inoculation of cell-free products of microbial growth.*
Answer: The microorganism must be found in abundance in all organisms suffering from the disease, but should not be found in healthy organisms.
The microorganism must be isolated from a diseased organism and grown in pure culture.
The cultured microorganism should cause disease when introduced into a healthy organism.
The microorganism must be reisolated from the inoculated, diseased experimental host and identified as being identical to the original specific causative agent.
One of the following is the appropriate sample for the isolation of Salmonella typhi during the first week of a suspected cases of typhoid fever
blood
Which of the following is not true for E. coli?
can cause meningitis in neonates
The most frequently isolated type of H. influenzae in cases of bacterial meningitis in children between 6 months to 2 years is
serotype b
Which is the incorrect statement concerning gonorrhea?
The definitive diagnosis can be made by detecting at least a 4-fold rise in antibody titer to N. gonorrheae.
The vaccine currently used for the prevention of S. pneumoniae is made from
capsular polysaccharides from 23 S. pneumoniae serotypes
Which of the following tests is more specific in the diagnosis of syphilis?
TPHA (Treponema Pallidum Hemagglutination Test)
The tubercle, a lesion in tuberculosis, is characterized by
bacilli surrounded by lymphocytes and fibroblasts
The following are some general characteristics of Mycobacterium leprae except
A. acid fast rods / B. humans are the only significant reservoir / C. can be grown readily in the laboratory using either artificial media or cell culture* / D. cell wall has high lipid content
The pathogenesis of Mycobacterium tuberculosis follows certain norms. Which of the following statements is not true?
A. Mycobacterium tuberculosis produces an exotoxin and contains an endotoxin in its cell wall.* / B. Reactivation is seen primarily in debilitated or immunocompromised patients. / C. The primary lesion usually appears in the lungs. / D. Dissemination may be by bloodstream or erosion of tubercle and spread to contagious areas.
The diagnosis of chickenpox can be done by
A. symptomatology, including characteristic appearance of lesions / B. Serology / C. Tzanck’s smear / D. All of the above*
A 21-year old female patient came to you complaining of profuse vaginal discharge with finshy odor and itching of the vulva. Examination of the discharge showed vaginal epithelial cells that contain tiny pleomorphic bacilli within the cytoplasm (clue cells). The pathogen involved is
Gardnerella vaginalis
A characteristic “rose spots” may appear in the second to the third week of this disease.
Typhoid fever
Which of the following would best describe disinfectants and antiseptics?
Disinfectants are used in inanimate objects while antiseptics are used for living forms like human tissues.
The essential antigen in pneumococcus that protects the organism from phagocytosis and is used to classify the organism into specific antigenic types is
capsular polysaccharide
The isolation and identification of Staphylococcus epidermidis from one bottle of a series of three blood cultures most likely indicates which of the following conditions?
staphylococcal contamination
Which specimen should not be refrigerated after collection even if it cannot be processed at once?
blood
Coagulase test is used to classify
Staphylococci
CSF is collected in three vials for laboratory examination. Which vial should not be used for bacteriology?
vial 1
The incubation period of influenza is commonly
2 – 4 days
The etiologic agent of about 90% of post-transfusion hepatitis is
Hepatitis C
The hepatitis profile done on a patient showed a HbsAg negative, IgM core antibody negative and Hbs antibody positive results. What would be the best interpretation for these results?
The patient is immune to Hepatitis B.
Which of the following is not a contraindication for administering a live attenuated viral vaccine?
administration of another live vaccine
Hepatitis C poses a big challenge in clinical practice because of the
A. presence of genetic subtypes that present with different pathogenic mechanisms. / B. difficulty in developing vaccines due to the genetic heterogeneity and possible antigenic variability. / C. problems in laboratory diagnosis due to possible antigenic variability among genetic types / D. all of the above*
Core window phase in HBV infection means
positive for anti-HBe and anti-Hbc antibodies
The presence of transient rashes among dengue patients has been observed to be a prognostic sign associated with
mild illness and recovery
The presence of antibodies against the primary cause of dengue infection means
protection against the infecting serotype for a long time
The cause of shock in dengue and other hemorrhagic fevers is
A. partly due to the virus / B. largely due to immune-mediated damage of virus-infected cells / C. both A and B are correct*
The problem of cross infection with different serotypes of dengue relates to
A. difficulties in developing a safe vaccine / B. difficulty in establishing diagnosis / C. both A and B are correct*
Mycobacterium tuberculosis is an acid fast organism and this is due to which of the following
mycolic acid
Acute bronchiolitis is common in the first 2 years of life and results from inflammatory obstruction of the small airways. The most common causative agent is
Respiratory syncytial virus
Blue green pus in wounds and burns is due to
Pseudomonas aeruginosa
A 23-year old pregnant woman decided to continue with her pregnancy even when she tested positive for anti-rubella IgM on the 8th week of gestation. Which of the following findings will indicate congenital rubella?
anti-rubella IgM in the baby