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1. Why is it important to keep the blood to culture medium ratio at 1:10 and what is the anti-coagulant in blood culture bottles?

2. You are the Supervisor of a Micro Lab and have noticed that 80% of all blood cultures from the ER are contaminated with skin flora(turn positive). Describe how you should rectify this problem?

3. List the common bacterial pathogens in meningitis along with one host-related factor and one virulence-related factor for each pathogen.

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Collen Von
Collen VonLv2
28 Sep 2019
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Related questions

1. Select which of the following are mechanisms used by pathogens to avoid host defenses and to successfully colonize the host.

A. Producing siderphores to obtain iron from the host for growth

B. producing adhesins for damaging host cells

C. Avoiding IgA proteases for avoiding secretory IgA

D. Avoiding secretory IgA by rapid turnover of pili

E. Producing toxic substances to suppress host responses

2. People considered obese have a different normal flora in the gastrointestinal tract compared to people who are considered lean.

A. true

B. false

3. Which of the following is NOT a mechanism used by pathogens for avoiding or surviving phagocytosis?

A. Killing macrophages and neutrophils

B. Colonizing the phagocyte

C. inhibiting opsonization

D. Inhibiting phagocte chemotaxis

E. these are all methods of avoiding or surviving phagocytosis

4.Which of the following immune responses is best suited to prevent a virus from infecting a cell?

A. complement cascade

B. inflammation

C. Virus-specific antibodies

D. Fever

E. phagocytic cells

5. Which of the following is NOT a method used by pathogens for penetrating skin or mucous membranes?

A. Injection of effector proteins that induce endocytosis

B. Exploiting antigen-sampling processes

C. these are all mechanisms for penetrating skin or mucous membranes

D. Exploiting an injury

E. Production of endotoxin

6. Antibodies, which are produced as part of the adaptive immune response, can sometimes be damaging rather than beneficial. People suffering from an autoimmune disease called antiphospholipid antibody syndrome (APS) make antibodies that bind to phospholipids. Some of the signs and symptoms affected individuals experience are blood clots, stroke, heart attack, and kidney damage. What is the likely cause of these symptoms?

A. the anti-phospholipid antibodies cuse immune complexes that lodge in the affected organs

B. The person fails to make protective antibodies

C. The anti-phospholipid antibodies weaken certain organs that contain fat

D. the person makes antibodies that bind inappropriately to bacterial capsules, preventing phagocytosis of these cells

E. Cell damage caused by binding of these antibodies initates inappropriate coagulation events which inferfere with blood flow in affected organs.

7. Only Gram-positive bacteria produce exotoxins

A. true

B. False

8. Which of the following members of the normal microbiota inhibit the growth of Candida albicans?

A. Lactobacilus species

B. Staphylococci species

C. E. coli

D. Neisseria species

E. Propionibacterium species

9. Would an antibody response against the B subunit of an A-B toxin protect against the effects of the toxin?

A. yes. if antibodies bind to the B protion, the toxin can no longer bind to target cells and will thus not affect those cells

B. No, even if antibodies bindto the B portion of the toxin, it is the A portion that actually causes damage to the cell

C. This question cannot be answer. The immune system does not mount a strong response against proteins, so this situation is unlikely to occur.

D. Yes, if antibodies bind to the B protein, that portion of the toxin does not become activated, and thus does not damage the host cell

E. No, even if antiibodies bind to the B portion of the toxin, the toxin is still taken into the host cell by phagocytosis, damaging that cell

10. Please select the correct definition of balanced pathogenicity.

A. A host-parasite relationship in which the parasite persists in the host, causing maximal harm. The pathogen becomes more virulent while the host becomes increasingly susceptible.

B. A mechanism that allows bacteria to transfer gene products directly into host cells, inducing changes such as altering the cell's cytoskeleton structure

C. A generated balance in the microbiome that may be caused by taking antimicrobial medication. it generally helps the host maintain optimal health

D. A situation in which an abnormally high number of T-helper cells are stimulated, causing a massive release of cytokines.

E. A host-parasite relationship in which the parasite persists in the host while causing minimal harm. The pathogen becomes less virulent while the host becomes less susceptible

11. Bacteria may survive phagocytosis by

A. preventing encounters with phagocytes AND preventing fusion of two pathogosomes

B. avoiding recognition and attachment of lymphocytes AND lysinf the phagosomes

C. preventing fusion of the lysosome with the phagosome AND mimicking host molecules

D. lysing the phagosome AND mimicking host molecules

E. preventing fusion of the lysosome with the phagosome AND lysing the phagosome

12. In two of Koch's postulates (#2 and #3), a pure culture of the organism is required. Which of the following would NOT be a possible consequence of using a contaminated culture?

A. these would all be consequences of using contaminated cultures

B. Even though there's a contaminating microbe present, as long as the original suspect microbe is also present, the disease should still manifest in test animals and the organism should still be recoverable from test animals. As such, there's really no consequence to using a contaminated culture

C. The problem is that one microbe may be toxic to other. It may have killed all of your suspect microbe in the culture. Therefore, you can't be sure that you're infecting your test animals with the microbe you suspect is causing the illness, or if it's only the sec. microbe.

D. you can't necessarily attribute the illness directly to the microbe in question; it may in fact be caused by the contaminating microbe

E. There's the possibility that the test animal might be acutely susceptible to the contaminating microbe, but completely resistant to the microbe you suspect causes the illness of interest. As such, when you introduce it into the test animal, it could confuse your final results.

1) What clinical manifestation do Staphylococcus aureus and Staphylococcus epidermidis share? A) nosocomial infections B) protein A antiphagocytic factor C) hyaluronidase enzyme D) enterotoxins E) staphylokinase 2) Which of the following has been historically classified as Gram-negative bacteria but is genetically more similar to low G + C Gram-positive bacteria? A) mycoplasmas B) Mycobacterium C) Clostridium D) Propionibacterium E) Nocardia 3) What is one virulence factor that differentiates Staphylococcus aureus from other species of staphylococci? A) It has a capsule. B) It can produce coagulase. C) It produces catalase. D) It can live on the surface of the skin and in cutaneous oil glands. E) It produces lipase. 4) Over 90% of Staphylococcus aureus isolates are penicillin-resistant. Why? A) They have loosely organized polysaccharide slime layers. B) They produce coagulase. C) Cell division occurs in successively different planes, and the daughter cells remain attached to one another. D) They produce β-lactamase. E) They produce staphylokinase, which dissolves fibrin threads in blood clots. 5) A woman comes to the emergency department with fever and vomiting. She soon develops a red rash all over her body, and her blood pressure begins to drop. What is one possible diagnosis? A) erysipelas C) scarlet fever B) endocarditis D) toxic shock syndrome E) staphylococcal food poisoning 6) Bacteria collected from a severely inflamed wound are sent to the lab for analysis. The results come back as follows: Gram-positive cocci in irregular clusters, kinase and coagulase positive, and able to grow in the presence of most antibiotics except vancomycin. The bacteria in the wound are most likely _______ A) Enterococcus. C) Staphylococcus aureus. B) Staphylococcus epidermidis. D) methicillin-resistant Staphylococcus aureus (MRSA). E) Streptococcus pyogenes (group A streptococcus). 7) Which of the following statements about "flesh-eating" streptococci is FALSE? A) It is caused by a group A streptococcus. B) It is also known as necrotizing fasciitis because it travels along the fascia. C) It causes death in over 50% of cases. D) It is considered a common complication of pyoderma. E) It involves toxemia. 8) Streptococcus agalactiae is associated with which of the following diseases? A) neonatal bacteremia B) neonatal meningitis C) neonatal pneumonia D) both neonatal bacteremia and neonatal meningitis E) neonatal bacteremia, neonatal meningitis, and neonatal pneumonia 9) What differentiates virulent strains of Streptococcus pneumoniae from nonvirulent strains? A) the species-specific teichoic acid present in its cell wall B) the type of Lancefield antigen it produces C) the presence of a polysaccharide capsule that protects it from digestion after endocytosis D) the type of toxins it produces E) the extent of the hemolytic zone it produces when it is grown on blood agar 10) Otitis media may lead to dangerous meningitis in children due to infection with _____ A) Streptococcus agalactiae. B) Streptococcus pneumoniae. C) Streptococcus mutans. D) Enterococcus. E) Mycoplasma pneumoniae. 11) Which of the following streptococci is associated with dental caries? A) viridans streptococci B) Streptococcus pyogenes C) Streptococcus pneumoniae D) Streptococcus equisimilis E) Streptococcus arginosus 12) Anthrax, which means "charcoal" in Greek, derives its name from _____ A) the airborne endospores it produces. B) the staining properties of the bacillus under the microscope. C) the black eschars it produces on human skin. D) its ability to invade the bloodstream and produce toxemia. E) the high mortality it causes in infected individuals. 13) Which of the following bacteria produce one of the most deadly bacterial toxins known? A) Clostridium perfringens C) Clostridium tetani B) Clostridium difficile D) Clostridium botulinum E) Corynebacterium species 14) Which of the following bacteria can cause life-threatening pseudomembranous colitis? A) Clostridium difficile B) Staphylococcus aureus C) Streptococcus pyogenes D) Enterococcus species E) Clostridium botulinum 15) How does the toxin from Clostridium tetani produce its action? A) It fuses irreversibly to neuronal cytoplasmic membranes, blocking release of acetylcholine at synaptic clefts. B) The smaller polypeptide of its toxin can block the release of inhibitory neurotransmitters by inhibitory neurons in the central nervous system, causing simultaneous contraction of both muscles in an antagonistic pair. C) It is a pyrogenic toxin, which triggers a diffused rash and, later, sloughing of skin. D) It destroys tissues, including muscle and fat. E) It produces antibodies that attack the neuromuscular junctions in skeletal muscle and prevent them from relaxing. 16) Listeria virulence is directly related to its ability to ______ A) produce powerful toxins. B) form very resistant endospores. C) live within cells and thus avoid exposure to the immune system of its host. D) easily become a pathogen in humans. E) resist most antimicrobial agents. 17) The pus from an abscess in a patient's jaw contains microbes that form yellowish grainy masses and appear filamentous under the microscope. Neither antifungal medication nor a normal course of antibiotics has been effective in treating the infection. The abscess is likely the result of infection with A) Actinomyces. B) Mycobacterium. C) Nocardia. D) Propionibacterium. E) Streptococcus. 18) What is the most common disease caused by Propionibacterium? A) acne B) food poisoning C) pneumonitis D) folliculitis 19) Streptococcus pneumoniae is a leading cause of ______ A) acne. C) pharyngitis B) furuncles. D) primary atypical pneumonia. E) otitis media. 20) The soil bacterium Nocardia asteroides can establish opportunistic infections of the _____ A) skin C) central nervous system B) lungs D) cardiovascular system. E) skin, lungs, and central nervous system

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