aerobic gram positive rods Flashcards

1
Q

are bacillus aerobic or anaerobic

A

aerobic

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2
Q

are bacillus gram positive or negative? what shape

A

gram positive rods

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3
Q

are bacillus spore producing

A

yes

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4
Q

why can bacillus spores be used for quality control of sterilisation procedures eg autoclave spore strips

A

very resistant towards drying, heat

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5
Q

what kind of symptoms (system) do bacillus cause and how does it cause it

A

gastrointestinal symptoms, caused by production of toxins

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6
Q

microscopy shape of bacillus

A

box shaped, occur in chains

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7
Q

what bacteria species is anthrax

A

bacillus

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8
Q

are anthrax spore producing

A

yes

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9
Q

where can anthrax spores be found

A

extremely tough spores, may be carried on animal hides, bone fertilisers. uncommon in major cities, usually rural areas. patient may have travel history or exposure to animals in eg mongolia

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10
Q

what bacillus is suitable for biological warfare

A

bacillus antracis ie anthrax

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11
Q

how does inhalation of anthrax differ from ingestion of anthrax

A

symptoms dependent on infection route. inhalation cause pulmonary anthrax, ingestion cause gastrointestinal anthrax

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12
Q

why is b anthracis suitable to be used for bioterrorism

A

aerosol delivery for effective dissemination

spore-forming hence difficult to eradicate

use drug resistant strains

high mortality rate

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13
Q

is lactobacillus gram positive or negative, aerobic or anaerobic, what is its shape

A

microaerophilic gram positive rod

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14
Q

what kind of environment does lactobacillus prefer to grow in

A

lactobacillus is acidogenic, prefer to grow in acidic environment. it is aciduric and produces acid to make environment for favourable for itself.

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15
Q

what bacteria can be used as probiotics

A

lactobacillus

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16
Q

where is lactobacillus part of the normal flora

A

gastrointestinal tract and female genital tract

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17
Q

what is role of lactobacillus in development of caries

A

progression of deep enamel lesions, pioneer organism on advancing front

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18
Q

is corynebacterium diphtheriae gram negative or gram positive

A

gram positive

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19
Q

is corynebacterium diphtheriae aerobic or anaerobic

A

aerobic

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20
Q

where is corynebacterium diphtheriae part of the normal flora

A

upper respiratory tract

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21
Q

what kind of upper respiratory infections can corynebacterium diphtheriae cause

A

patients mainly asymptomatic carriers. can cause throat infection under certain conditions. nasal, laryngeal, tracheal sites may also be infected

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22
Q

majority of corynebacterium diphtheriae is not pathogenic. how do the pathogenic strains cause disease

A

diphteria toxin

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23
Q

what does corynebacterium diphtheriae vaccine target

A

diphteria toxin

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24
Q

what kind of infection does toxigenic corynebacterium diphtheriae usually cause

A

skin infection and upper respiratory tract infection

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25
Q

what kind of infection does non toxigenic corynebacterium diphtheriae usually cause

A

skin infections

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26
Q

what are symptoms of corynebacterium diphtheriae infection

A

sore throat, malaise, fever, airway obstruction because oropharyngeal tissues slough off to form pseudomembrane that blocks airway, palatal paralysis, neuropathy, myocarditis, bull neck

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27
Q

what bacteria causes “bull neck”

A

corynebacterium diphtheriae

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28
Q

how is classical diphteria diagnosed

A

clinically. begin treatment before microbiological confirmation due to severity of disease

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29
Q

how to test for corynebacterium diphtheriae toxin production

A

PCR

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30
Q

how is corynebacterium diphtheriae treated

A

antiserum (antitoxin)

antibiotics: penicillin, erythromycin

patient should be isolated

31
Q

how can spread of corynebacterium diphtheriae be prevented

A

toxoid vaccine and antibiotics given to patient and contacts (antibiotic prophylaxis)

32
Q

describe listeria monocytogenes (gram, aerobic/an, shape)

A

gram positive aerobic short rod, slender

33
Q

What temperatures is listeria monocytogenes able to grow at

A

able to grow even at 4ºC hence can continue to grow even if food is refrigerated

34
Q

how is listeria monocytogenes transmitted

A

foodborne, causing gastroenteritis outbreaks

35
Q

clinical presentation of listeria monocytogenes

A

flu like illness in pregnant women
still born baby, baby with disseminated infection or meningitis after delivery

invasive infections in people of extreme ages and in immunocompromised

36
Q

what go beaded gram positive rods appear as microscopically and why

A

filamentous, branching, string of pearls appearance due to uneven uptake of stan

37
Q

what kind of bacteria is actinomyces

A

gram positive facultative anaerobe

38
Q

what kind of bacteria is nocardia spp.

A

grampositive, aerobic actinomyces

39
Q

what bacteria is modified acid fast positive

A

nocardia spp. takes up acid fast stain to some degree but not as much as mycobacterium

40
Q

who does nocardia spp. usually infect

A

immunocompromised patients

41
Q

what are the clinical presentations of nocardiosis

A

pulmonary infections, brain abscesses, skin/soft tissue infection

42
Q

how to treat nocardia spp

A

trimethoprim-sulphamethoxazole ie cotrimoxazole. give combinations of more than one antibiotic based on susceptibility testing. treat for more then one month due to concern of relapse

43
Q

does actinomyces cause acute or chronic infections

A

chronic infections, require long term treatment to prevent recurrence

44
Q

what bacteria can cause chronic canaliculitis

A

actinomyces

45
Q

how to treat actinomyces

A

surgical debridement with antibiotics

46
Q

what shape is mycobacterium

A

rod shaped

47
Q

is mycobacterium gram positive or negative

A

gram positive

48
Q

is mycobacterium aerobic or anaerobic

A

aerobic

49
Q

what bacteria appears pink on ziehl neelson stain and why

A

mycobacterium because it is acid fast bacilli and contains mycolic acid in cell wall

50
Q

what are the main pathogenic strains of mycobacterium. where are non pathogenic strains found

A

m tuberculosis and m leprae

all other species ala atypical mycobacteria/non tuberculous mycobacteria are environmental especially where there is water/moisture. tend to not be as pathogenic.

51
Q

how is tuberculosis transmitted and where does it usually infect

A

airborne via human to human spread. NOT DROPLET TRANSMISSION!! hence must use n95

pulmonary infection

52
Q

what percentage of patients gets infected following exposure to m tuberculosis

A

10%

53
Q

what are the classical tb symptoms

A

fever and night sweats, cough with sputum production, weight loss

54
Q

what type of necrosis is characteristic of tb infection

A

caseous necrosis

55
Q

what happens in primary pulmonary tb

A

ghon focus: spreads to regional lymph nodes, lymph nodes enlarge

granuloma formation in attempt to contatin infection

caseous necrosis

56
Q

what happens when tb progresses from primary stage

A

progression of primary lung lesion, pleural effusion

bacteremia. disseminated in blood stream (miliary infection)

57
Q

what can happen as a result of miliary infection

A

disseminated tb infection in blood stream can cause organ specific infection mimicking cancer, meningitis, genitourinary tract infection including kidneys

58
Q

what are the clinical manifestations of oral tuberculosis

A
non healing chronic ulcers
local lymph node enlargement
jaw osteomyelitis
inflammation
abscess
59
Q

how to diagnose tb

A

biopsy oral lesion and do afb microscopy and culture

histology for tissue/bopsy specimens
afb smear (microscopy), afb culture, molecular testing
60
Q

what is the downside to afb smear in trying to diagnose mycobacterium tb infection

A

unable to differentiate between tb and non tb mycobacteria

61
Q

how long does m tuberculosis culture take to grow

A

6-8 weeks

62
Q

what is lowenstein jensen media used for

A

tuberculosis

63
Q

how is tuberculosis cultured nowadays

A

MGIT system, liquid media

automated reading, more sensitive than lowenstein jensen solid media, faster positive results

64
Q

what is the advantage of using molecular methods to diagnose m tuberculosis

A

pcr gives same day results and able to differentiate m tuberculosis from other mycobacterium and able to detect rpob gene coding from rifampicin resistance

65
Q

how are patients treated for tb

A

if not resistant to rifampicin, multidrug therapy with rifampicin to avoid development of rifampicin resistant TB. extended treatment for 6 months or more

66
Q

what is time period for statutory notification of tb infection

A

72 hours

67
Q

what is the contact screening procedure for tb

A

tuberculin skin testing, quantiferon gold, t spot, x ray to exclude active disease

68
Q

how are patients with pan sensitive tuberculosis dealt with

A

isolated in negative pressure room until deemed non infectious

they become non infectious within 2 weeks of treatment

69
Q

what does bcg vaccine do

A

reduce risk of serioud tb eg meningitis tb but does not prevent you from getting infection. limited efficacy ie previously vaccinated patient can get active tb

70
Q

what is leprosy caused by

A

mycobacterium leprae

71
Q

compare grwoth rates of m tuberculosis, slow growing atypical mycobacterium, rapidly growing atypical mycobacterium

A

tb 2-3 weeks
slow 4-6 weeks
rapid within 1 week

72
Q

4 different types of clinical presentation of non tuberculosis mycobacterium infection (more common in immunocompromised)

A

lymphadenitis: single node in neck of young child who may not be immunocompromised. tb can also present this way. biopsy/sample lymph node

skin infection: direct inoculation. rapid growing hospital acquired eg post injection. slow growing community acquired eg traumatic inoculation, get cut on the beach

pulmonary disease: patient has pre existing chest disease eg chronic cough, all other pathologies must be excluded as NTM lung infection is rare

disseminated infection: chronic, in immunocompromised patients esp m. avium complex. prolonged treatment

73
Q

why is repeated isolation of same non tuberculosis mycobacterium necessary to diagnose pulmonary disease caused by atypical mycobacteria

A

atypical mycobacteria are environmental bacteria hence single positive cultures may be due to contamination of sample. require multiple cultures taken over several days all yielding positive results

should also get consistent clinical and radiological features

74
Q

how to treat non tb mycobacterium infection

A

surgical debridement of infective focus and antibiotic treatment

m. avium: calrithromycin, rifampicin, ethambutol

m kansasii: rifampicin, ethambutol, isoniazid

high rates of recurrence in pulmonary infections esp underlying lung disease, patient may not be able to get off treatment or may require baseline antibiotics