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Medical Microbiology > Lecture 12 > Flashcards

Lecture 12 Flashcards

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USMLE® Step 1 flashcards Biology 101 flashcards
1
Q

What are the general characteristics of Neisseria?

A

Gram– dipplococci; small nonmotile aerobes that are oxidase-positive, has pili; invasive

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2
Q

What is the reservoir for Neisseria?

A

STRICTLY human

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3
Q

What exotoxins do Neisseria species produce?

A

no exotoxins have been identified

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4
Q

What disease do Neisseria species cause commonly?

A

Gonorrhea

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5
Q

What is the second most common bacterial STI in USA?

A

Gonorrhea

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6
Q

What is the most (#1) common STI in USA?

A

HPV

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7
Q

What is the difference between a disease and infection?

A

one can have an infection without developing a disease

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8
Q

Why is using the term “STI” more accurate than using the term “STD”? (infection vs disease)

A

one can be infected but not form a disease and have no symptoms = asymptomatic but can pass on infection to another person who may develop symptoms = disease

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9
Q

Who first identified Neisseria species? What year?

A

Albert Neisser (German physician), 1879

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10
Q

What is another name for the Neisseria species?

A

Moraxella species

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11
Q

What are the 2 Neisseria species discussed?

A

N. gonorrheae and N. meningitides

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12
Q

What is another name for N. gonorrheae?

A

Gonococcus

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13
Q

What is another name for N. meningitides?

A

Meningococcus

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14
Q

What diseases does Gonococcus cause?

A

Gonorrhea

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15
Q

What diseases does Meningococcus cause?

A

bacterial meningitis and septicemia

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16
Q

How many known Neisseria/Moraxella species are found in humans?

A

10

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17
Q

What is gonorrhea (STI) called in the hood?

A

The Clap

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18
Q

What kind of pathogen is N. gonorrheae considered to be and why?

A

mucosal pathogen because it colonizes with mucosal epithelial membranes/surfaces

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19
Q

What are the 2 characteristics of all mucosal pathogens?

A

cannot survive outside of host and highly sensitive to light

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20
Q

What is the mode of transmission of N. gonorrheae?

A

vaginal/anal/oral sex (due to genital secretions) with someone infected (does not need to have the disease)

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21
Q

Is gonorrhea a new or old disease? What is the evidence?

A

old bacteria STI infected men from ancient world as well as Biblical references

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22
Q

What does “gono” and “rrhea” mean?

A

“gono” = seed and “rrhea” = flow

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23
Q

What does “asymptomatic carriage” mean?

A

pathogen is carried mostly via asymptomatic persons

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24
Q

What percentage of women are asymptomatic?

A

~20-40%

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25
Q

What percentage of men are asymptomatic?

A

~10%

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26
Q

Which gender is more susceptible to develop gonorrhea and why?

A

men because they are only 10% asymptomatic

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27
Q

Which gender is more likely to transmit gonorrhea and why?

A

women because they are more asymptomatic = will not know IF they are infected

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28
Q

What are the common symptoms of gonorrhea in women?

A

vaginitis (mild), increased vaginal discharge, vaginal bleeding between periods

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29
Q

In which gender does painful/burning sensation when urinating occur as a symptom of gonorrhea? What is this due to?

A

BOTH men and women; due to infection of urethral canal

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30
Q

What are the common symptoms of gonorrhea in men?

A

penile discharge (white, yellow, or green), painful/swollen testicles (less common)

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31
Q

What are the symptoms of gonorrhea in a rectal infection?

A

P-DABS = Painful bowel-movements, Discharge, Anal-itches, Bleeding, Soreness

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32
Q

Can symptoms of gonorrhea occur anywhere else in the body other than the reproductive tract?

A

Yes, like in the liver and pharynx

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33
Q

What is gonococcal conjunctivitis?

A

N. gonorrheae causes an eye infection in newborns from their infected mothers

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34
Q

How does gonococcal conjunctivitis occur?

A

women infected with N. gonorrheae (asymptomatic or not) pass the pathogen to the newborn via delivery thus affects eyes of the newborn

35
Q

How can gonococcal conjunctivitis be prevented?

A

via prophylactic treatment where drops of erythromycin are applied onto all newborn’s eyes to prevent infection in case if the mother is infected

36
Q

How many new cases/year of gonorrhea in the US? Is this an estimation or exact? Who does it include?

A

~700,000 = estimation as it includes reported cases and unreported asymptomatic cases of infected individuals

37
Q

What are 3 reasons for the many cases of gonorrhea?

A

1) acquired immunity doesn’t exist = can get reinfected | 2) use of oral contraceptives = help bacteria colonize | 3) symptoms in females may be mild = undetect disease = pass to sexual partners

38
Q

Between bacterial STIs and viral STIs, which is more treatable and why?

A

bacterial STIs = antibiotics available; antibiotics cannot treat viral STIs

39
Q

What is the 3rd most common STI in US?

A

syphillus

40
Q

How can one bring a rare STI to the US?

A

when one travels out of the country and has unprotected sex

41
Q

Which region of the world has the highest cases of gonorrhea?

A

Africa

42
Q

Which part of the US has the highest occurrence of gonorrhea?

A

south-east USA

43
Q

Which ethnic group in the US does gonorrhea highly occur in?

A

African-Americans

44
Q

What is the reason for the decline in gonorrheal cases (US) during 1945-1955?

A

war and production of antibiotics

45
Q

What is the reason for the increase in gonorrheal cases in the US during the 1960s?

A

sexual revolution #hippienation

46
Q

What is the reason for the decline in gonorrheal cases in the US from 1981?

A

increase awareness of STIs due to increase awareness of AIDS and HIV = more people started practicing safe sex

47
Q

What are the 5 virulence factors of N. gonorrheae?

A

pili, Opa surface proteins, IgA1 autotransporter, Lipo-oligosaccharide and peptidoglycan endotoxins

48
Q

What is the function of the pili in pathogenesis?

A

bind to surfaces

49
Q

What is the function of the Opa in pathogenesis?

A

bind to mucosal epithelial and phagocytic cells ; cell-cell signaling

50
Q

What is the function of the IgA1 autotransporter in pathogenesis?

A

acts as a protease cleaving IgA1 antibodies

51
Q

What is significant about the mechanism of the IgA1 autotransporter of N. gonorrheae?

A

these bacteria have been “born” to fight the host immune system at mucosal surfaces by releasing the IgA1 protease = will degrade and inactivate the IgA1 antibodies | makes sense because gonorrhea=old disease=N. gonorrhea knows how to attach mucosal epithelial cells

52
Q

Where are IgA1 antibodies found?

A

on mucosal surfaces

53
Q

What is the difference in the mode of invasion between Gonococcus and Meningococcus?

A

Gonococcus = no capsule = infection remains localized only to mucosal epithelial surfaces | Meningococcus = has capsule = infection not localized = can enter bloodstream and infect other organs

54
Q

What is antigenic variation and how does it occur?

A

changes in the composition/structure of “main” surface molecules on bacteria’s cell surface = allows them to avoid recognition by specific antibodies during the course of an infection | happens via random genetic rearrangements (change sequence = change structure)

55
Q

What structure on N. gonorrheae undergoes antigenic variation?

A

the pili

56
Q

What is the consequence of the antigenic variation mechanism of N. gonorrhea on us the hosts?

A

contributes to the lack of protective immunity during infection because the immune system never recognizes the bacteria, its always under some disguise = why people can be reinfected

57
Q

What are the 2 mechanisms N. gonorrhea uses to escape detection by the immune system?

A

antigenic variation and phase variation

58
Q

What is phase variation?

A

genes that encode for the specific outer-membrane proteins contain repeats | change the number of repeats = change sequence = change structure

59
Q

What structure on N. gonorrheae undergoes phase variation?

A

the Opa proteins

60
Q

What are the 4 methods of diagnosis to detect/identify presence of N. gonorrheae?

A

1) swab of discharge from infected area | 2) microscopy-Gram stain | 3) culture on selective media, biochemical assays | 4) PCR (4hrs, sensitive/specific)

61
Q

What was the first antibiotic used to treat gonorrhea and why is it no longer recommended for treatment?

A

penicillin, many penicillin-resistant strains

62
Q

What are 2 examples of antibiotics used for treatment?

A

quinolones and cephalosporins (= QuinoCephs)

63
Q

What is a rising problem in the treatment of gonorrhea, what is N. gonorrheae then considered as?

A

multi-drug-resistant strains on the rise - considers N. gonorrheae to be a Super Bug :(

64
Q

Are there vaccines available to prevent N. gonorrheae infections? Explain.

A

No vaccines available due to: changes (hyper-variablility) of surface proteins | blocking antiboies like the IgA1 autotransporter | N. gonorrheae spends most of time inside host = intracellular resistance (evolved to fight off host defenses)

65
Q

What is the reservoir for N. meningitides?

A

human

66
Q

What is the mode of transmission for N. meningitides?

A

direct contact and airborne; asymptomatic carriage also possible

67
Q

What are the 5 most common serogroups of N. meningitides?

A

A, B, C, W-135, Y

68
Q

What is bacteremia?

A

BACTERIA in the blood

69
Q

What is septicemia?

A

INFECTION in the blood

70
Q

What does the type of infection of N. meningitides that we have refer to?

A

infection of the membrane that surround the brain

71
Q

What are the 2 stages of bacterial meningitis?

A

1) bacteria enters blood and colonizes meninges | 2) inflamed meninges allows phagocytes and blood proteins to enter spinal fluid and brain

72
Q

What is the sequence of events of bacterial meningitis?

A

bacteria enters host via respiratory system &raquo_space; it crosses mucosal epithelial cells &raquo_space; enters bloodstream &raquo_space; lands on central nervous system, colonizes membranes of CNS and brain

73
Q

What causes the inflammation of the meninges?

A

the infection, colonization of the meninges

74
Q

What is responsible for most of the damage and why?

A

the inflammation causes/allows blood proteins and phagocytes to enter the spinal fluid and brain

75
Q

What are the initial symptoms of bacterial meningitis?

A

fever, rash, stiff neck, headache (= FRSH)

76
Q

What percent of cases lead to death and what is significant about this?

A

3% and includes individuals that have been treated with antibiotics

77
Q

What are the virulence factors of N. meningitides?

A

capsule and LOS endotoxin

78
Q

What specimen is collected for diagnosis?

A

blood

79
Q

What are the methods to diagnose/detect the presence of N. meningitides?

A

culture, microscopy, PCR-based assay

80
Q

What antibiotics are used to treat bacterial meningitis?

A

cephalosporins & penicillin (CephaPen)

81
Q

How many vaccines are available to help prevent infection due to N. meningitides?

A

4

82
Q

What are the vaccines that contain the capsular polysaccharide serogroups?

A

Meningococcal ACWY vaccine (A, C, W-135, Y serogroups included) and Meningococcal B vaccine

83
Q

Which vaccine is ineffective on infants and why?

A

Meningococcal ACWY vaccine because it does not contain the B serogroup

Medical Microbiology (20 decks)

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