Question 1 - Single Best Answer
The major mechanisms of INTERCELLULAR genetic exchange between bacterial cells are:
transposition, conjugation, transduction conjugation, transformation, transduction recombination, transposition, transformation transposition, transduction, transformation conjugation, competence, conduction
Question 2 - Single Best Answer
A major difference in the mechanisms of gene expression in bacteria compared with eukaryotes is:
bacteria do not have ribosomes or other membrane-containing organelles bacteria do not have RNA polymerase transcription and translation of a gene occur simultaneously the genetic code is different for bacteria compared with eukaryotes the sequences directing nuclear export are at the 3' end of bacterial genes
Question 3 - Single Best Answer
An acid-fast stain of the sputum of a patient who has suffered severe productive coughing, including coughing up blood, weight loss, and night sweats reveals red, rod-shaped bacteria. The cell wall of these bacteria most likely contains:
lipopolysaccharide teichoic acids a capsule composed of glutamate cord factor and wax D None of the above - these are Mycoplasma - wall-less bacteria
Question 4 - Single Best Answer
Periplasm is:
the name for cytoplasm in wall-less bacteria the name for the fluid if one homogenizes bacterial cells the material transferred during conjugation the space surrounding gram-positive bacteria taken up by the thick peptidoglycan the space between the inner and outer membranes
Question 5 - Single Best Answer
Gram-negative bacteria overcome the permeability barrier of the outer membrane by:
porins a second level of proton-motive force across the membrane hydrolysis of ATP in the periplasm driving active transport across the outer membrane having the outer membrane cover only part of the bacterial cell None of the above - the outer membrane does not create an additional permeability barrier to gram-negative bacteria
Question 6 - Single Best Answer
The component of smooth lipopolysaccharide on an intact bacterial cell most likely to encounter antibodies during infection is:
lipid A core oligosaccharide teichoic acid diaminopimelic acid O antigen
Question 7 - Single Best Answer
Mixed populations of bacteria growing in communities attached to solid surfaces in liquid environments are most likely to produce:
toxins lipopolysaccharide teichoic acid periplasm glycocalyx
Question 8 - Single Best Answer
Among medically relevant bacteria, spores are made by:
gram-positives only gram-negatives only anaerobes only aerobes only acid-fast bacteria only
Question 9 - Single Best Answer
Which of the following is NOT associated with the bacterial cytoplasmic membrane?
electron transport motility transport of nutrients replication endocytosis/exocytosis
Question 10 - Single Best Answer
Which of the following antibiotics does NOT target bacterial ribosomes?
tetracyclines aminoglycosides quinolones macrolides streptogramins
Question 11 - Single Best Answer
Sulfa drugs and trimethoprim are effective antibiotics because:
humans must synthesize folic acid, while bacteria must acquire it as a nutrient humans lack dihydropteroate synthetase and dihydrofolate reductase bacteria must acquire iron from the host using siderophores humans lack dihydropteroate synthetase and human dihydrofolate reductase is different from the bacterial enzyme anaerobic bacteria metabolize these drugs into their active forms, while humans do not
Question 12 - Single Best Answer
Rifampin is effective against bacteria because:
the bacterial RNA polymerase is different from that of humans bacteria lack a nuclear membrane bacteria do not produce actin-based cytoskeletal elements bacteria do not produce ribosomes bacteria produce DNA gyrase
Question 13 - Single Best Answer
A pleural effusion contains 100 bacteria/mL fluid. The bacteria double once every hour. If the bacteria are not killed by the host, how many bacteria will there be in the fluid 4 hours later?
400/mL 1,600/mL 16,000/mL 100,000/mL 1,000,000/mL
Question 14 - Single Best Answer
Generalized transduction requires that:
the phage be temperate the prophage integrates into the host genome a piece of host genome is packaged into a phage particle the F plasmid integrates into the host chromosome the F plasmid excises from the chromosome with a piece of host genome attached
Question 15 - Single Best Answer
Medically, the most important consequence of conjugation is:
Hfr-mediated transfer of chromosomal genes moving virulence genes among diverse bacteria the phenocopy state moving antibiotic resistance genes among different bacteria None of the above - conjugation is only of use in the laboratory
Question 16 - Single Best Answer
Based on their structure, it is likely that transposons arose by:
temperate phage integrating into the host genome two copies of an insertion sequence flanking a gene an F plasmid integrating into the chromosome transformation the cassette model of antigenic variation
Question 17 - Single Best Answer
The mechanism of phase variation is usually:
integration of a phage into the host genome integration of a plasmid into the host genome copying non-expressed copies of genes into an expression site inversion of a segment of DNA deletion of a segment of DNA
Question 18 - Single Best Answer
Which of the following is a difference between vancomycin and bacitracin?
Vancomycin is active against gram-positives, while bacitracin is active against gram-negatives. There is no known resistance to vancomycin, while resistance to bacitracin is common because it is sold over the counter. Vancomycin targets peptidoglycan synthesis, while bacitracin targets protein synthesis. Vancomycin is similar in structure to penicillins, while bacitracin is similar in structure to cephalosporins Vancomycin binds to the peptidoglycan building block itself, while bacitracin binds to the lipid carrier that transports the building block
Question 19 - Single Best Answer
Polymyxins have a relatively high therapeutic index because:
they target peptidoglycan they target porins they target the periplasm they target plasmids None of the above - polymyxins have a relatively low therapeutic index
Question 20 - Single Best Answer
Penicillin (beta-lactam) resistance of Streptococcus pneumoniae is most often caused by:
resistant forms of penicillin-binding proteins acquired long ago from another unknown resistant organism the accumulation of point mutations in genes encoding penicillin-binding proteins gradually increasing resistance plasmid-encoded beta-lactamase genes the penicillin building block changing to D-Ala-D-Lactate None of the above - Streptococcus pneumoniae is always resistant to penicillins
Question 21 - Single Best Answer
The most common site of entry of infectious agents in disease is:
the skin (epidermis) the mucosal membranes direct inoculation by trauma direct inoculation by arthropod or animal bite None of the above
Question 22 - Single Best Answer
A seventy year old man who has been mentally very sharp until 3 days ago is brought to your office by his wife who says he has become increasingly confused over the past several days. You find no fever or other obvious symptoms except a slight increased heart rate. You should immediately consider:
meningitis pneumococcal pneumonia Chlamydia pneumonia sepsis nvCJD
Question 23 - Single Best Answer
Adherence virulence factors are always:
proteins structures visible by electron microscopy nonspecific in their binding characteristics encoded on plasmids present on the microbial surface
Question 24 - Single Best Answer
In diseases caused by active infection, which of the following is NOT always done by pathogens?
multiplication in host tissues or fluids cellular or tissue damage invasion of host cells evasion of relevant host defenses None of the above - there are no optional steps in pathogenesis
Question 25 - Single Best Answer
Which of the following would NOT be expected to be a virulence factor of an intracellular pathogen of macrophages?
production of a capsule inhibiting phagosome-lysosome fusion production of catalase or superoxide dismutase escaping the phagosome into the cytoplasm resisting defensins
Question 26 - Single Best Answer
The difference between antigenic mimicry and antigenic cloaking is:
mimicry involves moving segments of DNA among different sites in the chromosome, while cloaking does not involve DNA rearrangements mimicry is for extracellular pathogens, while cloaking is for intracellular pathogens mimicry involves numerous forms of the antigen present among different strains, while cloaking requires genetic exchange mimicry is encoded on a plasmid, while cloaking is encoded by bacteriophage mimicry uses bacterial antigens, while cloaking uses host antigens for evasion
Question 27 - Single Best Answer
Superantigens act by:
killing T cells stimulating T cells stimulating macrophages suppressing B cells suppressing neutrophils
Question 28 - Single Best Answer
Endotoxic effects are mediated by:
activated T cells immunoglobulins lysis of host cells apoptosis cytokines
Question 29 - Single Best Answer
Type III secreted proteins are unique in that they:
are produced by the host in response to infection. are a component of peptidoglycan are injected into host cells have toxic activity even though they remain within bacterial cells stimulate T cells to produce antibodies
Question 30 - Single Best Answer
An example of fomite transmission is:
a dog bite a tick bite unprotected sex eating contaminated meat handling a doorknob
Question 31 - Single Best Answer
Pseudomonas aeruginosa strains isolated from cystic fibrosis patients are unique in that they:
form endospores are obligate anaerobes contain no endotoxin in the cell wall form mucoid colonies due to alginate overproduction produce a superantigen
Question 32 - Single Best Answer
Patients with whooping cough are most infectious (contagious) during what stage of the illness?
incubation period paroxysmal catarrhal convalescent spasmodic
Question 33 - Single Best Answer
Because of their complexity and specificity, the molecular diagnosis tests are best used for:
differentiating streptococci from staphylococci differentiating among different species of gram-negative bacteria differentiating strains of a pathogen in epidemiology predicting virulence of pathogens differentiating among different serotypes of streptococci
Question 34 - Single Best Answer
Which of the following does NOT require special media for culture (other than blood agar)?
Bordetella pertussis Corynebacterium diphtheria Streptococcus pneumoniae Mycoplasma pneumoniae Legionella pneumophila
Question 35 - Single Best Answer
What do the vaccines for pneumococcal pneumonia and diphtheria have in common?
They both induce anti-bacterial antibodies that cause opsonization They both induce cell mediated immunity to kill intracellular bacteria They both induce IgA that inhibits adherence of the bacteria to the respiratory tract. They both induce IgG anti-toxin antibodies that neutralize systemic toxin None of the above.
Question 36 - Single Best Answer
What do diphtheria toxin and pertussis toxin have in common?
The both form pores in host cells They both ADP-ribosylate host proteins They both stimulate cAMP levels They both inhibit protein synthesis They both are encoded on plasmids
Question 37 - Single Best Answer
Isoniazid is used to treat tuberculosis because it:
inhibits DNA synthesis inhibits peptidoglycan formation inhibits cell-mediated immunity inhibits mycolic acid production inhibits lipopolysaccharide production
Question 38 - Single Best Answer
A major difference between Legionnaire's disease and Pontiac Fever is:
Legionnaire's disease is life-threatening and strikes debilitated hosts, while Pontiac Fever is a flu-like disease of even healthy people. Legionnaire's disease is caused by a gram-negative rod while Pontiac Fever is caused by gram-positive cocci Legionnaire's disease is not contagious, but Pontiac Fever is contagious. Legionnaire's disease is an aerobic infection, while Pontiac Fever is an anaerobic infection. Legionnaire's disease has a vaccine, while Pontiac Fever has no vaccine.
Question 39 - Single Best Answer
All of the following are true about the Group A streptococcal M protein EXCEPT:
It is the major virulence factor of group A streptococcus Strains without M protein are avirulent Acquired immunity to Group A strep infection is M type specific It is responsible for hemolysis seen on the surface of blood agar plates It allows the organism to evade phagocytosis by neutrophils
Question 40 - Single Best Answer
The rationale for treating Group A streptococcal pharyngitis includes which of the following:
Shorten time of clinical illness Prevent nonsuppurative complications (e.g. Acute rheumatic fever) Prevent development of streptococcal cervical adenitis Prevent development of peritonsillar abscesses All of the above
Question 41 - Single Best Answer
Which of the following is NOT one of the Jones major criteria for diagnosing acute rheumatic fever?
carditis migratory polyarthritis subcutaneous nodules fever erythema marginatum
Question 42 - Single Best Answer
The relevance of anti-streptolysin O and anti-DNAse B antibodies in streptococcal infections is:
They are induced by the vaccine They protect against colonization They are used in diagnosing pharyngitis in place of culture. They are used in diagnosing previous infection in cases of suspected nonsuppurative sequellae They are the cause of the damage for nonsuppurative sequellae
Question 43 - Single Best Answer
A 48 year old woman presents to your office with complaints of two weeks of swelling of her ankles, face, and hands and rusty colored urine. In your office her blood pressure is noted to be elevated (169/95), and her urine dipstick shows the presence of protein and blood. Approximately a month before her presentation to your office, she had an episode of cellulitis (infection of the skin). This woman's condition most likely:
followed infection with a nephritogenic strain of group A streptococcus. resulted from direct infection of her kidney with group A streptococcus is not post-streptococcal glomerulonephritis because she did not have pharyngitis is a sequellae of infection with Corynebacterium diphtheriae is a sequellae of Pontiac Fever
Question 44 - Single Best Answer
A temperate phage
can cause lysogenic conversion can cause specialized transduction can lyse a bacterial cell can code for toxins all of the above
Question 45 - Single Best Answer
The treatment of choice for Mycoplasma pneumonia is
penicillin antitoxin toxoid an antibiotic that inhibits protein synthesis an antibiotic that can enter eukaryotic cells
Question 46 - Single Best Answer
Based on the relationship between mechanism of action and genetics, resistance to tetracycline would most likely be expected to be:
acquired by lysogenic conversion a chromosomal mutation in a ribosomal RNA encoded on a plasmid a deletion of a gene encoding a ribosomal protein a mutation in a gene encoding transpeptidase
Question 47 - Single Best Answer
Which of the following is usually colonized with normal flora?
urine in the bladder spinal fluid blood pharynx lung
Question 48 - Single Best Answer
A woman went to the hospital for a breast biopsy for possible cancer. Two days after the biopsy she had a fever and did not feel well. The following day her blood pressure began to drop. The biopsy site was oozing pus. A microscopic exam revealed gram-positive bacteria in clusters. The drop in the woman's blood pressure was due to:
catalase endotoxin a superantigen the fever bacteria in her blood
Question 49 - Single Best Answer
The characteristic signs of pneumonia heard on auscultation (listening) can all be attributed to:
denuded respiratory epithelium narrowing of the bronchioles an excess amount of oxygen in the lungs fluid in the lungs the bacterial polysaccharide
Question 50 - Single Best Answer
A feverish, obviously ill, child comes to your office for an exam. She appears to be having some trouble breathing. You note that her throat is red and that there is a grayish-yellow exudate covering her trachea. As you are removing this membrane-like substance, you note that it is tough, almost like leather, and bleeding ensues. If this child is not treated with antibiotics what are the likely consequences?
Nothing, she has a self-limiting viral infection She may get rheumatic fever She may die due to exotoxin-induced damage to her heart muscle cells She will surely get pneumonia Her blood pressure will fall and she will die of septicemia
Question 51 - Single Best Answer
The immediate source of the bacteria causing pneumococcal pneumonia following influenza virus infection is usually:
exogenous by the respiratory route from children to adults endogenous from hospital personnel from improperly washed hands
Question 52 - Single Best Answer
A professor at UF has recently developed a test called Tru-spu. It measures neutrophil (leukocyte) esterase with a dip stick. It is being advertised as a help in diagnosing pneumonia. The reason it might be helpful is
it could distinguish saliva samples from sputum it could differentiate between chlamydial and mycoplasma pneumonia it would obviate (make unnecessary) the need for a blood culture it would obviate the need for chest x-rays
Question 53 - Single Best Answer
One of the most serious effects of the severe coughing in whooping cough is:
it forces fluid into the lungs it can cause cyanosis it can cause the appearance of a pseudomembrane in the throat it can spread the bacteria to pregnant women who may, then, abort their babies it can cause hemoptysis
Question 54 - Single Best Answer
A 1-year-old baby girl was brought to your office in January because of fever, rhinorrhea, and a harsh, "barking" cough. The cough did not produce any sputum. The child's mother said that the baby's appetite was "o.k." and that she had not been vomiting. Which of the following is most likely to be the etiologic agent?
a virus Streptococcus pneumoniae Bordetella pertussis Corynebacterium diphtheriae Pseudomonas aeruginosa
Question 55 - Single Best Answer
Symptoms of pneumonia caused by Mycoplasma pneumonia are most similar to disease caused by:
Streptococcus pneumoniae Chlamydia pneumoniae Legionella pneumophila Streptococcus pyogenes Staphylococcus aureus
Question 56 - Single Best Answer
NAD participates in the action of diphtheria toxin as a:
hydrogen acceptor electron donor energy source donor of ADP-ribose site of binding of the B portion
Question 57 - Single Best Answer
Fermentation and respiration are both methods for the regeneration of what substance?
NAD NADH2 ATP glucose energized membrane
Question 58 - Single Best Answer
Primary tuberculosis in most immunologically normal individuals presents as:
"cough of 100 days" flu-like symptoms or no symptoms bloody sputum miliary TB apical cavitary lesions
Question 59 - Single Best Answer
One of the most effective experimental drugs for sepsis is:
antibodies to endotoxin antibodies to platelet activating factor non-steroidal anti-inflammatory drugs activated protein C Interleukin-1
Question 60 - Single Best Answer
The objections to using BCG as a vaccine against tuberculosis include:
It will only work in some parts of the world. It will cause disease in AIDS patients. It will cause a positive PPD test. It is not very efficacious. All of the above
Question 61 - Single Best Answer
The damage in TB is caused by:
exotoxin wax D LPS antibody cell mediated immunity
Question 62 - Single Best Answer
Which of the following does NOT usually cause permanent damage to respiratory tissues during infection?
Anaerobes Staphylococcus aureus Streptococcus pneumoniae Gram-negative rods None of the above - they all cause permanent tissue damage
Question 63 - Single Best Answer
The cause of rigors is:
neurological damage hypoxia bacteremia hyperventilation septic shock
Question 64 - Single Best Answer
When should a chest X-ray be performed?
If a sputum sample cannot be obtained for culture If the sputum Gram stain is inconclusive If the sputum Gram stain shows the presence of bacteria and neutrophils If a sputum Gram stain cannot be performed Whenever pneumonia is being considered in the diagnosis
Question 65 - Single Best Answer
Each of the following is considered at risk for tuberculosis EXCEPT:
single males sexually active young adults alcoholics inmates immigrants
Question 66 - Single Best Answer
The Ghon complex is:
calcified lung lesions from primary tuberculosis the combination of local and disseminated granulomas part of miliary tuberculosis the constellation of abnormal blood gases, renal and hepatic failure, and inflammation associated with secondary tuberculosis the combination of Mycobacterium tuberculosis, Mycobacterium avium, and Mycobacterium intracellularle None of the above
Question 67 - Single Best Answer
Antibiotic treatment of active tuberculosis:
should only be initiated after antibiotic susceptibility has been completed to avoid using antibiotics that are doomed to fail in the patient should only be initiated if the patient has a life-threatening infection to prevent the unnecessary use of antibiotics and selection for resistant organisms should consist of multiple antibiotics consists of larger and longer doses of the same antibiotics used to treat community acquired pneumonia can be skipped if the patient responds to vaccination with BCG after diagnosis
Question 68 - Single Best Answer
The most sensitive method for diagnosing active tuberculosis is:
acid fast stain of sputum PPD test chest X-ray sputum culture Ghon complex reactivity
Question 69 - Single Best Answer
In treating sepsis it is most important to initially
use a broad spectrum antibiotic as soon as possible identify the organism causing it identify the site of infection use antibiotics against only anaerobic microbes so as not to increase the potential for resistance use antifungal agents
Question 70 - Single Best Answer
Foul smelling odor of sputum is usually indicative of:
tuberculosis diphtheria fungal infection spore-forming infection anaerobic infection
Question 71 - Single Best Answer
What percentage of antibiotics in the United States is administered to humans, as opposed to farm animals?
about 99% about 90% about 50% about 10% 1%
Question 72 - Single Best Answer
The bacteria in this micrograph are most consistent with:
being able to grow on a MacConkey plate. being bacitracin sensitive and catalase positive being optochin-sensitive and catalase-negative being citrate-positive being lactose-negative
Question 73 - Single Best Answer
The bacteria inoculated in the bottom citrate tube are most likely associated with:
green sputum permanent tissue damage in the lungs a positive Phadebact test a positive Ghon complex glomerulonephritis
Question 74 - Single Best Answer
The bacteria on this blood agar plate are causing alpha (green) hemolysis and the disc contains optochin. These bacteria most likely cause:
green colored sputum current jelly sputum rust colored sputum thin, watery sputum None of the above - they are normal oral flora.
Question 75 - Single Best Answer
If this Gram stain is the only thing you have so far, to diagnose these bacteria the next thing is:
perform a coagulase test. a Phadebact test. a catalase test. an oxidase test. Nothing - you are ready to prescribe antibiotics.