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Medical Microbiology > Lecture 13 > Flashcards

Lecture 13 Flashcards

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USMLE® Step 1 flashcards Biology 101 flashcards
1
Q

What are the general characteristics of Chlamydiae species?

A

Gram– cocci | obligate intracellular pathogens (only survive and multiply inside the host) | invasive, nonmotile, smallest bacteria discussed, small genomes, auxotrophic for many amino acids and 3 of 4 nucleotide-triphosphates (cannot produce them)

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2
Q

What is a unique characteristic of Chlamydiae species?

A

2 cellular forms in developmental cycle = 2 different sizes (one is small and one is larger)

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3
Q

What is the reservoir for Chlamydiae species?

A

humans and animals (includes birds)

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4
Q

What does it mean when scientists say that Chlamydiae species lack peptidoglycan cell walls?

A

cell walls are not detected but their genomes contain genes to synthesize peptidoglycan cell walls; don’t know if those genes are being expressed or why we cannot detect the murein

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5
Q

How does the auxotrophic characteristic of Chlamydiae help explain their small genome size?

A

Chlamydiae species need what they can’t synthesize from the host = have a small genome because they are only limited to what they can synthesize

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6
Q

What is the #1 leading bacteria STI in the US?

A

chlamydia

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7
Q

How many new cases/year of chlamydia occurs in the US?

A

2.9million (estimated for the asymptomatic)

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8
Q

What is a nickname of Chlamydiae species and why?

A

“stealth pathogens” because they hide from the host immune system

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9
Q

Which Chlamydiae species is the best studied?

A

C. trachomatis

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10
Q

What type of tissues does C. trachomatis typically like to infect?

A

mucosal areas

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11
Q

What are the 2 genuses of Chlamydiae? What is the difference?

A

Chlamydia and Chlamydophila; no distinguishing differences, practically the same thing

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12
Q

What are the 4 agents of human chlamydial infections (includes chlamydia)

A

Chlamydia trachomatis: biovar trachoma serovars A-C, biovar trachoma serovars D-K, and biovar lymphogranuloma venereum and Chlamydia pneumoniae

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13
Q

Which Chlamydia agent causes trachoma?

A

C. trachomatis biovar trachoma serovar A-C

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14
Q

Which Chlamydia agent causes STI chlamydia?

A

C. trachomatis biovar trachoma serovar D-K

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15
Q

What does Chlamydia trachomatis biovar lymphogranuloma venereum cause?

A

invasive STIs = infections that go beyond initial infection, affects other organ systems ; very rare and more serious

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16
Q

Which Chlamydia agent causes pneumonia?

A

C. pneumoniae

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17
Q

Which agent of animal chlamydial infections causes psittacosis in humans? What animal does it usually infect?

A

C. psittaci, usually causes respiratory and GI illness in birds

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18
Q

Does Chlamydia cause an old or new world disease?

A

depends: C. trachomatis causing eye infection is an old world disease but C. trachomatis causing the STI chlamydia is a new world disease

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19
Q

When was STI chlamydia first reported?

A

1970s

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20
Q

How can a pathogen that causes an eye infection, now cause a sexually transmitted infection?

A

indirect contact between C. trachomatis infected eye and uninfected genitals

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21
Q

What are 3 facts that STI chlamydia is big and common?

A

MOST common bacterial STI in US, most commonly reported/notifiable disease in US, C. trachomatis = largest proportion of all STDs reported to CDC

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22
Q

In STI chlamydia, what does C. trachomatis mainly infect? (4)

A

mucosal epithelial membranes of: cervix, urethra, conjunctiva, throat

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23
Q

Which mucosal epithelial cells does C. trachomatis not infect? Why do you think that is?

A

vaginal cells may lack the receptor for the bacteria to invade in these cells

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24
Q

What is the 3 modes of transmission of C. trachomatis biovar trachoma serovar D-K?

A

infected secretions through sexual contact (hetero and gay males, or use of sex toy covered with the secretions) | during birth = mom transfer bacterium to newborn’s eyes = possibility of it developing pneumonia | contact of infected genital secretions to hands to eyes = trachoma

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25
Q

What is trachoma?

A

a chronic conjunctivitis caused by C. trachomatis serovars A-C

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26
Q

How common is trachoma in the US?

A

rare

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27
Q

In which regions in the world is trachoma often common?

A

Sub-Sahara Africa, Middle-East, Asia

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28
Q

What is the leading cause of preventable blindness, globally?

A

trachoma

29
Q

After how many years does vision loss usually occur after initial infection?

A

15-20 years

30
Q

What are the symptoms of trachoma?

A

eye discharge, swollen lids, trichiasis (turned-in lashes), bright-light sensitivity, increased HR (heart rate), other complications

31
Q

What are the antibiotics used to treat trachoma?

A

azithromycin (Azi) and tetracycline (Tetra) = AziTetra

32
Q

What are the 2 cellular forms of Chlamydia trachomatis?

A

elementary bodies (EBs) and reticulate bodies (RBs)

33
Q

What are the characteristics of elementary bodies?

A

small (0.25µm) | infectious and invasive | extracellular | metabolically inactive

34
Q

What are the characteristics of reticulate bodies?

A

larger (0.6-0.8µm) | intracellular | metabolically active, divides inside host cell

35
Q

What other “life-cycle” is similar to that of C. trachomatis?

A

viruses – 2 forms

36
Q

What is the sequence of events of the C. trachomatis life cycle?

A

EB interact with host cell, invade and enter it via membrane-bound vesicles &raquo_space; once inside = convert to RB form inside their vesicle &raquo_space; RB multiply &raquo_space; convert back to EB-form in order to be released &raquo_space; after conversion = release = infect other cells

37
Q

When would C. trachomatis ever deviate from its life cycle?

A

when conditions are not optimal for bacteria to multiply = prevent them from following regular life cycle and stay inside their vesicles where they grow a little more, once conditions are normal = return back to normal size and resume cycle

38
Q

What conditions would be un-optimal for C. trachomatis to multiply/divide inside the host cell?

A

temperature, presence of antibiotics, immunoresponse molecules and cells present, interferon-gamma, nutrient limitation

39
Q

What happens to the host cell when the new generation of EBs are released?

A

host cell dies

40
Q

Which secretion system do C. trachomatis utilize?

A

Type III secretion system

41
Q

What are the 5 virulence factors of C. trachomatis?

A

Type-III secretion system, Tarp, CPAF, MOMP, autotransporter proteins

42
Q

What does “Tarp” stand for and what is it’s role as a virulence factor for C. trachomatis?

A

translocated actin recruiting protein that interacts with the host cell to recruit actin

43
Q

What do the C. trachomatis virulence factors CPAF and MOMP stand for?

A

CPAF = Chlamydia protease-like activity factor | MOMP = major Outer Membrane Protein (probably functions as an adhesin)

44
Q

How long does it take for STI chlamydia symptoms to appear after infection?

A

1-3 weeks

45
Q

What percentage of women are asymptomatic to STI chlamydia?

A

75%

46
Q

What percentage of men are asymptomatic to STI chlamydia?

A

50%

47
Q

What are the STI chlamydia symptoms seen in women?

A

pelvic pain and bleeding between periods or after sex

48
Q

What are the STI chlamydia symptoms seen in men?

A

redness at penile tip

49
Q

What are the STI chlamydia symptoms seen in BOTH genders?

A

discharge, dysuria,

50
Q

What are the conditions/complications that can develop in women infected with STI chlamydia?

A

PID, cervicitis, salpingitis, endometritis

51
Q

What are the conditions/complications that can develop in men infected with STI chlamydia?

A

Reiter’s syndrome, epididymitis and prostatitis

52
Q

What are the conditions/complications that can develop in BOTH genders infected with STI chlamydia?

A

urethritis, proctitis (rectum/anus)

53
Q

What is the Fitz-Hugh Curtis Syndrome?

A

(perihepatitis) scar tissue formation around liver from PID and chlamydia infection

54
Q

What is Bartholinitis?

A

Bartholin’s glands infected/inflammed

55
Q

Which women are at risk for contracting STI chlamydia?

A

unsafe sex, multiple partners who have multiple partners, high risk age group = 15-24yo

56
Q

Which men are at risk for contracting STI chlamydia?

A

unsafe sex and partners with cervicitis and PID

57
Q

What is Salpingitis?

A

inflammation of fallopian tubes

58
Q

What are the Bartholin’s glands?

A

racemous glands posterior of vagina, secretes mucus and lubricates vagina

59
Q

In what locations of the body would a swab specimen be obtained from? (both genders)

A

men = urethra; women = cervix

60
Q

What are the differences in diagnostics between the different sites of infection?

A

genitals = can do PCR | throat/anal = use of cell-tissue culture methods as Chlamydiae can only survive intracellularly in mucosal epithelial cells

61
Q

What treatment is available against STI chlamydia?

A

most antibiotics work as so far no significant antibiotic-resistant strains have surfaced | most antibiotics need to be taken for 7 days

62
Q

Are there vaccines available for STI chlamydia?

A

no vaccines are commercially used

63
Q

What are the prevention methods used against C. trachomatis serovar D-K?

A

safe sex and condoms

64
Q

What is one mode of prevention that people believe provides protection against C. trachomatis serovar D-K infection? Is this true?

A

Nonoxynol-9 = spermicide = does NOT prevent infection

65
Q

What is Chlamydophylia psittaci?

A

pathogen causes human psittacosis

66
Q

What is human psittacosis?

A

(ornithosis) = zoonotic pneumonia

67
Q

How many cases/year does psittacosis occur in the US?

A

100-200

68
Q

What is a method used to diagnose for the presence of C. psittaci in humans?

A

blood-based assay (checks for antibody titer) or send specimen to specialized lab for culture

69
Q

What treatment is available against psittacosis?

A

most antibiotics work

Medical Microbiology (20 decks)

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