legionella neisseria mycoplasma chlamydia

Question 1

is legionella gram positive or negative

Answer 1

gram negative

Question 2

why is legionella fastidious

Answer 2

special culture media required. require L cysteine for growth, enhanced by inclusion of iron salts

Question 3

describe staining of legionella

Answer 3

thin, faintly staining rods

Question 4

where is legionella found

Answer 4

water, moist environment. colonise most domestic water systems, humidifiers, water sprinklers, dental unit water systems

Question 5

what organism is important for the survival and growth of legionella in nature

Answer 5

protozoa

Question 6

how does legionella multiply in humans

Answer 6

multiply intracellularly, in macrophages and monocytes

Question 7

what disease can legionella cause

Answer 7

legionnaires disease: pneumonia with symptoms of systemic disease. transmission by contaminated aerosol producing devices, not contagious

pontiac fever: short fever with no pneumonia, self limiting

Question 8

what agar plate is used to visualise legionella

Answer 8

broncho-alveolar lavage: immunofluorescent stain, culture on BCYE agar

Question 9

how to diagnose legionella

Answer 9

broncho alveolar lavage, antigen detection in urine (only serotype 1), serology

hard to see in gram stain

Question 10

how to treat legionella

Answer 10

fluoroquinolones, macrolides

Question 11

how to clear dental unit water system of legionella

Answer 11

purge with disinfectants effects in liquid phase against established biofilms

Question 12

is neisseria gram negative or positive

Answer 12

gram negative

Question 13

what are the growth requirements of neisseria

Answer 13

enhanced by humidity, co2

Question 14

where is neisseria meningitidis carried in host

Answer 14

carried asymptomatically in the nasopharynx

Question 15

how is neisseria meningitidis transmitted

Answer 15

respiratory droplet or close contact

Question 16

which serogroups of neisseria meningitidies responsible for invasive infection leading to meningitis, meningococcaemia, septicemia + meningitis

Answer 16

A, B, C, W, X, Y

Question 17

what medium is neisseria gonorrhae cultured on

Answer 17

thayer martin medium which suppresses growth of bacteria that is not neisseria (direct plating best)

Question 18

what swabs can be used for neisseria gonorrhae culture

Answer 18

males can use urethral discharge. femals cannot use gram stain as a lot of other colonising bacteria in vaginal discharge, use culture or PCR test

Question 19

how to treat meningococcus

Answer 19

benzylpenicillin, ceftriazone, meropenem (does not clear throat carriage)

Question 20

how to treat gonococcus

Answer 20

ceftriazone, azithromycin

ciprofloxacin resistant

Question 21

symptom of meningococcus

Answer 21

skin rash

Question 22

symptoms of gonococcus

Answer 22

discharge, pain on urination ie dysuria for males

for females, early infection asymptomatic.
may later see vaginal discharge, dysuria, intermenstrual bleeding. ascending infection may occcur from endocervical site, ascend to uterua and form scar, resulting in sterilisation or salpingitis (pelvis inflammation)

Question 23

what can gonococcus cause in babies

Answer 23

gonococca ophthalmia neonatorum – blindness due to bilateral conjunctivitis following vaginal delivery from infected mother

Question 24

chlamydia is a small obligate intracellular pathogen that cannot be visualised by gram stain because it lacks

Answer 24

peptidoglycan

Question 25

where in host cell does chlamydia replicate

Answer 25

in host cell cytoplasm, forming intracellular inclusions (reticulate bodies) extracellular form is elementary body

Question 26

does chlamydia provide immunity after initial infection

Answer 26

no

Question 27

what kind of cells are chlamydia cultures in for forensic purposes

Answer 27

mccoy cells

Question 28

how to diagnose chlamydia trachomatis

Answer 28

pcr (urine or swab). serology not useful for std but high igm may be of value in systemic infection antigen detection/immunofluorescence not accurate enough culture not available in routine labs, and mianly for forensic purposes

Question 29

how to diagnose chlamydia pneumoniae and psittcaci

Answer 29

serology, microscopy by direct immunofluorescence, pcr

Question 30

which chlamydia strain responsible for std infection

Answer 30

c. trachomatis (serotypes d to k)

Question 31

symptoms of c trachomatis infection

Answer 31

usually asymptomatic. can cause urethritis, dysuria, pyuria, cervicitis, salpingitis

Question 32

what is trachoma

Answer 32

caused by c trachomatis scarring of conjunctiva, conjunctiva contracts and eyelash pulled to surface of eye, scratching it, causing blindness

Question 33

name some symptoms of lymphogranuloma venereum (c trachomatis, uncommon in developed countries, serotypes L1, L2, L3)

Answer 33

inflammation of lymph ducts and nodes, ulcers, genital papules and ulcers, inguinal lymphadenopathy, fever, headache, myalgia

Question 34

what is reiter's arthritis caused by

Answer 34

c trachomatis serotypes d to k. 1 to 3 weeks post infection. dysuria, conjunctiva, arthritis. can't pee, can't see, can't climb a tree

Question 35

treatment for chlamydia trachomatis

Answer 35

doxycyline, azithromycin, erythromycin

Question 36

where is chlamydia psittacci found in environment

Answer 36

bird droppings

Question 37

how does c psittaci spread in the body

Answer 37

haematogenous spread to the spleen and liver

Question 38

clinical effects of c pneumoniae

Answer 38

sporadic, atypical pneumonia, dry cough

Question 39

how does chlamydia infect cells

Answer 39

infect non ciliated epithelial cells and stimulate infiltration of polymorphonuclear leukocytes and lymphocytes leading to fibrosis. immune modulating properties.

Question 40

why is mycoplasma able to pass through filters used to remove bacteria

Answer 40

smallest free living bacteria 0.2-0.3um

Question 41

why are beta lactams ineffective against mycoplasma

Answer 41

no cell wall hence no PBP

Question 42

why is mycoplasma fastidious

Answer 42

require preformed nucleic acid precursors and cholesterol

Question 43

describe mycoplasma growth on agar

Answer 43

colonies can be seen with naked eye

Question 44

why are mycoplasma not found in the environment

Answer 44

require host cell for nutrients

Question 45

what are the toxic metabolic products of m pneumoniae

Answer 45

hydrogen peroxide superoxide radicals

Question 46

clinical presentation of m pneumoniae

Answer 46

tracheobronchitis, atypical pneumonia, pharyngitis, croup, fever, headache, non productive cough

Question 47

does m pneumoniae provide immunity after infection

Answer 47

no

Question 48

how to diagnose mycoplasma pneumonae

Answer 48

special culture media enriched by pepton basal medium with yeast extract serology (cold agglutinin, elisa igm, complement fixation) PCR

Question 49

effect of mycoplasma on salivary glands if it is found there

Answer 49

hypofunction