- | Page
MMSC 438 EXAM 2 (WITH COMPLETE
SOLUTIONS)
Question : URT normal biota
Correct answer: lots of normal biota, particularly in the mouth
-viridans strep -nonhemolytic strep -anaerobes -CoNS -diphtheroids -micrococcus -candida (yeast)
Question : LRT normal biota
Correct answer: there is no actual normal biota present
-sputum is a common sample that is used, and has to pass through the mouth where it will become contaminated with normal biota -something is only considered a pathogen if it is in greater concentration than a normal biota organism
Question : respiratory tract defense mechanisms
- | Page
Correct answer: -competitive inhibition: normal flora of the URT and mouth prevent pathogens from establishing themselves
-musociliary elevator: ciliated epithelial cells in the URT help
push up any pathogens that enter, and remove them by coughing or sneezing
-immune response: alveolar macrophages, neutrophils,
antibodies and complement kill pathogens in the respiratory tract
Question : LRT mandatory reporting
Correct answer: if isolated in ANY quantity, report
-strep pyogenes -legionella -mycobacteria -viruses -agents of bioterrorism
Question : respiratory bacteria defense mechanisms
- | Page
Correct answer: -evasion of host defenses: avoiding phagocytosis, surviving inside of phagocytes, inactivating complement, forming biofilms
-adhesion to host respiratory cells: prevents bacteria from being
expelled by coughing and sneezing, allows infection to be established
-toxin production: diphtheria and pertussis are mediated by
toxins that lead to systemic symptoms
Question : transmission of respiratory infections
Correct answer: bacteria of the respiratory tract are highly
contagious and spread quickly
-person to person: airborne droplets are released through
coughing and sneezing, seasonal variations (e.g. flu season) may cause increase in a particular pathogen
-aspiration of endogenous biota: normal biota of the mouth can
be aspirated and establish an infection
-trauma: puncture of a lung can lead to infiltration of bacteria
into the lung
-environment/ animals: pathogens can originate from animals
(e.g. avian flu, swine flu), certain locations can have higher incidence of certain pathogens
- | Page
-fomites: surfaces that have been touched by infected material
can transmit the pathogen to another individual
Question : colonizer
Correct answer: a bacteria that is present in too small of a
quantity to cause disease, and therefore is not considered a pathogen
-DOES NOT CAUSE DISEASE
-if the numbers of the organism increased it could be a pathogen
Question : pathogen
Correct answer: bacteria that are considered significant when
isolated because they are in high enough numbers to be causing disease
Question : normal biota
Correct answer: bacteria that is always present in a specific site
and is not harmful to an immunocompetent host as long as it stays in that site