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Microbiology > Obligate Intracellular Bacteria And Mycoplasma > Flashcards

Obligate Intracellular Bacteria And Mycoplasma Flashcards

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Biology 101 flashcards
1
Q

What are obligate intracellular bacteria and give an example

A

Bacteria that grow in only cells and don’t grow in media , have dimorphic growth cycle- they assume two shapes when growing instead of the normal binary fission
Chlamydiae

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2
Q

Chlaymdiae were mistaken to be viruses true or false

A

True

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3
Q

What is the family, genus and species of chlamydiae

A

family
Chlamydiaceae

genera : Chlamydia & Chlamydophila

•Three species in the genera infect humans.

•Chlamydia trachomatis
•Chlamydophila pneumoniae
Chlamydophila psittaci

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4
Q

Which cells do chlamydiae infect and where do they multiply in the cells

A

Epithelial cells and in the cytoplasm of the host cell

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5
Q

Chlamydiae lack mechanism for metabolism of energy processing true or false

A

True

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6
Q

Chlamydia trachomatis depend on the host cell for what

A

Energy in the form of ATP

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7
Q

Which cells do chlamydia trachomatis grow on

A

McCoy cells , Hela 229 cells and yolk sac of chick embryo

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8
Q

What are the two shapes that the bacteria assumes

A

Elementary body and reticulate body

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9
Q

How many serotypes or serovars does CT have and name em

A

15 namely

A, B,Ba, C,D,E,F,G-K,L1,L2,L3

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10
Q

Chlamydiae are Gram negative bacteria true or false

A

True

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11
Q

Which serotypes of C. Trachomatis cause ocular or eye infections and what disease do they cause

A

A,B,Ba,C
Trachoma

D-K
Inclusion conjunctivitis, ophthalmia neonatum

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12
Q

If the serotypes that causes eye infection gets to the genitourinary system will it cause an infection there?

A

No it won’t

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13
Q

Which serotypes of CT cause genitourinary infections and the diseases associated

A

Male- D-K
Non-gonococcal urethritis, proctitis, epididymitis, dysuria,

Female-D-K
cervicitis, PID, infertility in women, salpingitis
Infertility with tubal occlusion, abortion, premature birth

Male and Female
L1-L3

Lymphogranuloma venereum (LGV)

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14
Q

Which serotypes of CT cause respiratory infections and the disease it causes

A

D-K

Neonatal atypical pneumonia’s

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15
Q

The Chlamydia cell wall has large CRP - cystic rich protein which makes up the thin peptidoglycan layer true or false

A

True

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16
Q

Explain the growth cycle of CT

A

When CT is infecting, it assumes the elementary body shape and enters into the cytoplasm of the cell. Gradually they get into the epithelial cells after 1-8 hours
From 12-24 hours, both the EB and the RB are seen in the cell and form inclusion in the cell
24-30 hours, the RB multiply so more of them are seen in the cytoplasm and few of the EB are seen in the cytoplasm
40 hours- many RB change into EB
48-72 hours- The EB destroy the cell and come out of the cell to infect new cells

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17
Q

Chlamydial infections are frequently asymptomatic true or false

A

True

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18
Q

•Visual loss in trachoma, ectopic pregnancy or infertility and pelvic inflammatory disease (PID) are the most severe sequelae of C. trachomatis infection.
•These are caused by tissue damaged by chlamydia-induced inflammation.
True or false

A

True

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19
Q

Explain how trachoma is spread and caused

A

Trachoma is spread by eye seeking flies, fingers and contaminated articles.
•It is caused by conjunctival scarring leading to distortion of the eyelids and abrasion of the cornea by the eyelashes.
•Active trachoma is characterized by the presence of lymphoid follicles on the conjunctiva. A disease of children but blindness occurs mainly in adults.

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20
Q

Explain how ophthalmic neonatorum is spread and caused

A

This condition develops in infants around 14 days after birth, from the mother during birth through a chlamydia-infected cervix.
•The disease presents as a swelling of the eyelids and orbit, a purulent infiltration of the conjunctiva which does not respond to cleaning of the eye or to chloramphenicol eye ointment.
•Diagnosis is confirmed by laboratory examination of a conjunctival swab obtained after removing pus from the eye.

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21
Q

How is adult inclusion conjunctivitis spread and how does it occur

A

Inclusion conjunctivitis is most prevalent in sexually active young people being spread from genitalia to the eye.
•In the acute stage it presents as a follicular conjunctivitis, often with a mucopurulent discharge, which persists if untreated.
•The disease is milder and usually self-limiting and rarely causes visual loss.

22
Q

C.trachomatis serovars D – K are responsible for about 30% of cases of non-specific urethritis in men. True or false
•Asymptomatic men are serving as a reservior of infection in the community. True or false
•In symptomatic patients, varying amounts of mucopurulent discharge are produced. This occasionally progresses to epididymitis or prostatis, especially in those aged less than 35 years.true or false

A

True
True
True

23
Q

Explain CT genitourinary infection in women

A

C. trachomatis serovars D – K cause mucopurulent cervititis and urethritis in symptomatic women
•Asymptomatic women harbour the organism in their cervix, a risk to their partners, offspring and to themselves.
•C. trachomatis infection in women results in endometritis, followed by infection of the fallopian tubes to cause acute salpingitis.
•Salpingitis + endometritis = PID

24
Q

What swab for

Women is used to check for chlamydia

A

Endocervical swab

25
Q

Explain LGV

A

Genital tract infections with C.trachomatis serovars L1, L2 or L3 may present as lymphogranuloma vereneum, commonest in the tropics

  • LGV begins with a genital ulcer or chancoid followed by lymphadenopathy of the regional lymph nodes
  • LGV infection can persists and spread to the gastro-intestinal and genito-urinary tracts.
26
Q

Which Chlamydiae causes pneumonia

A

Chlamydophila pneumoniae
This organism causes pneumonia, pharingitis, bronchitis, otitis and sinusitis with and incubation period of about 21 days
•Ch. pneumoniae is one of the common causes of community-acquired pneumonia.
•The organism is a chronic often insidious, respiratory pathogen to which there appears to be little immunity.

27
Q

What does Chlamydophila psittaci cause

A

Avian strains of Ch. psittaci cause psittacosis or ornithosis in man. Ornithosis is the disease acquire from birds other than psittacines.

•The incubation period is about 10 days and the illness ranges from an ‘influenza-like’ syndrome, with general malaise, fever, anorexia, sore throat, headache and photophobia.

28
Q

How is Chlamydia diagnosed in the lab

A

Cultivation
•C.trachomatis can be demonstrated by characteristic iodine-staining inclusions in McCoy or Hela 229 cell tissue culture.

•Cell culture necessitates special transit of specimens to the laboratory to ensure chlamydial viability is sustained

Laboratory Diagnosis
2. Antigen detection
•In smears of infected exudate from patients, elementary bodies (EBs) may be identified with fluorescein-labelled monoclonal antibodies and fluorescence microscopy. For smaller number of samples

  • Chlamydial antigen, usually LPS, may also be detected by enzyme immuno-assay eg. ELISA. For large number of samples.
  • Positive results need to be confirmed
  1. Nucleic acid detection
    •The best nucleic acid amplification based tests with sensitivity and specificity approaching 100%
29
Q

Which chlamydia is difficult to culture

A

Chlamydophila pneumoniae

30
Q

How is Chlamydia treated

A

The antibiotic of choice is doxycycline or azithromycin in adults and erythromycin in babies
•Penicillins inhibit, but do not kill Chlamydia and should not be used.
•Treatment must be given for a minimum of 7 days.
•In managing neonatal Chlamydial conjunctivitis and atypical pneumonia, systemic antibiotics especially oral erythromycin should be used.
•Chloramphenicol eye drops, often used to treat neonatal conjunctivitis are not effective against Chlamydiae.

31
Q

How is C trachomatis transmitted

A

The main mode of transmission for C. trachomatis are flies or contaminated secretions (trachoma) or sexual intercourse (genital tract infection)

  • Blindness affects 6 – 9 million adults, particularly women who care for infected children
  • Trachoma-induced blindness will increase for some years as populations in the developing world increase their life expectancy
32
Q

How is Chlamydia controlled

A

Prevention of trachoma rely on antibiotic prophylaxis with oral azithromycin and tetracycline eye ointment

•Environmental hygiene improvements such as the introduction of clean water.

•Community screening programmes for asymptomatic infections should be instituted.
34
Control
•It is essential that infected partners be traced and treated.

•In cases of neonatal infection the mother and her partner(s) should be examined and treated.

33
Q

Diagnosis requires laboratory tests, preferably those based on detection of chlamydial nucleic acid
True or false

A

True

34
Q

Where do mycoplasma grow and where are they found

A
  • Mycoplasmas are the smallest prokaryotic organisms (while Chlamydia is eukaryotic)that are capable of growth and reproduction outside the living host cell.
  • They are found in man, animals, plants, insects, soil and sewerage.
35
Q

Mycoplasma easily infects people due to their size true or false

A

True

36
Q

Name some characteristics of mycoplasma

A

They are highly pleomorphic because they lack rigid cell wall and instead are bounded by a triple layered ‘ unit membrane’ instead of cell wal

37
Q

What should mycoplasma media contain

A

Natural protein (usually blood serum)and sterol for growth

38
Q

What inhibits mycoplasma

A
  • Mycoplasmas are inhibited by tetracycline or erythromycin

* The growth pattern is inhibited by specific antibodies.

39
Q

They can replicate in cell free media and on agar, the colonies have what we call fried-egg appearance
True or false

A

True

40
Q

Mycoplasmas have an affinity for mammalian cell membranes. During infection process, they are extracellular
True or false

A

True

41
Q

Name five species of mycoplasma isolated from man

A

M.fermentalis
M. orale (oral cavity) M. pneumonia
M. salivarium (saliva) M. genitalium (genital)
Ureaplasma urealyticum

42
Q

Most of the Mycoplasmas encounted in human mucosal or genital tracts are commensals.
True or false

A

True

43
Q

What is M hominis and I urealyticum associated w

A

M. hominis is a pathogen associated with post partum fever and also found with other bacteria in the PID

•U. urealyticum is associated with non-gonococcal urethritis in men.

44
Q

Why isn’t microscopy useful for mycoplasma diagnosis

A

Cuz they’re too small

45
Q

What samples can be taken to check for mycoplasma

A

The organism can be cultured using specimen from the throat, respiratory secretions and urethra secretions.

46
Q

How is mycoplasma cultured

A

Inoculate sample into Heart Infusion Peptone Broth.
•Incubate at 370C
•Identify organism by the use of specific antiserum which inhibit the growth of the organism.

•PCR assay (rapid, sensitive and specific) is currently being used.

47
Q

How is mycoplasma treated

A

Administer tetracycline or a macrolide to adults and erythromycin to children and pregnant women

  • Azithromycin is active against a wide range of mycoplasmas
  • A broad spectrum antibiotic should be included for the treatment of PID
48
Q

Where is M fermentas found in the body

A

Joints of patients with chronic arthritis

49
Q

Mycoplasmas are the smallest organisms that grow in cell-free bacteriological media. They have no peptidoglycan and may assume variety of shapes
True or false

A

True

50
Q

Where is mycoplasma found in the body

A

•They are found in the respiratory and genital tracts of man and many animal species and sometimes invade bloodstream to gain access to joints and other organs.
.
50
Summary
•M. pneumoniae is a pathogen for the human respiratory tract. About a quarter of such infections in children result in pneumonia

•M. genitalium and Ureaplasma urealyticus are a cause of acute and chronic non-gonoccocal urethritis in men

Microbiology (9 decks)

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