aerobic gram positive rods Flashcards
are bacillus aerobic or anaerobic
aerobic
are bacillus gram positive or negative? what shape
gram positive rods
are bacillus spore producing
yes
why can bacillus spores be used for quality control of sterilisation procedures eg autoclave spore strips
very resistant towards drying, heat
what kind of symptoms (system) do bacillus cause and how does it cause it
gastrointestinal symptoms, caused by production of toxins
microscopy shape of bacillus
box shaped, occur in chains
what bacteria species is anthrax
bacillus
are anthrax spore producing
yes
where can anthrax spores be found
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
what bacillus is suitable for biological warfare
bacillus antracis ie anthrax
how does inhalation of anthrax differ from ingestion of anthrax
symptoms dependent on infection route. inhalation cause pulmonary anthrax, ingestion cause gastrointestinal anthrax
why is b anthracis suitable to be used for bioterrorism
aerosol delivery for effective dissemination
spore-forming hence difficult to eradicate
use drug resistant strains
high mortality rate
is lactobacillus gram positive or negative, aerobic or anaerobic, what is its shape
microaerophilic gram positive rod
what kind of environment does lactobacillus prefer to grow in
lactobacillus is acidogenic, prefer to grow in acidic environment. it is aciduric and produces acid to make environment for favourable for itself.
what bacteria can be used as probiotics
lactobacillus
where is lactobacillus part of the normal flora
gastrointestinal tract and female genital tract
what is role of lactobacillus in development of caries
progression of deep enamel lesions, pioneer organism on advancing front
is corynebacterium diphtheriae gram negative or gram positive
gram positive
is corynebacterium diphtheriae aerobic or anaerobic
aerobic
where is corynebacterium diphtheriae part of the normal flora
upper respiratory tract
what kind of upper respiratory infections can corynebacterium diphtheriae cause
patients mainly asymptomatic carriers. can cause throat infection under certain conditions. nasal, laryngeal, tracheal sites may also be infected
majority of corynebacterium diphtheriae is not pathogenic. how do the pathogenic strains cause disease
diphteria toxin
what does corynebacterium diphtheriae vaccine target
diphteria toxin
what kind of infection does toxigenic corynebacterium diphtheriae usually cause
skin infection and upper respiratory tract infection
what kind of infection does non toxigenic corynebacterium diphtheriae usually cause
skin infections
what are symptoms of corynebacterium diphtheriae infection
sore throat, malaise, fever, airway obstruction because oropharyngeal tissues slough off to form pseudomembrane that blocks airway, palatal paralysis, neuropathy, myocarditis, bull neck
what bacteria causes “bull neck”
corynebacterium diphtheriae
how is classical diphteria diagnosed
clinically. begin treatment before microbiological confirmation due to severity of disease
how to test for corynebacterium diphtheriae toxin production
PCR
how is corynebacterium diphtheriae treated
antiserum (antitoxin)
antibiotics: penicillin, erythromycin
patient should be isolated
how can spread of corynebacterium diphtheriae be prevented
toxoid vaccine and antibiotics given to patient and contacts (antibiotic prophylaxis)
describe listeria monocytogenes (gram, aerobic/an, shape)
gram positive aerobic short rod, slender
What temperatures is listeria monocytogenes able to grow at
able to grow even at 4ºC hence can continue to grow even if food is refrigerated
how is listeria monocytogenes transmitted
foodborne, causing gastroenteritis outbreaks
clinical presentation of listeria monocytogenes
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
what go beaded gram positive rods appear as microscopically and why
filamentous, branching, string of pearls appearance due to uneven uptake of stan
what kind of bacteria is actinomyces
gram positive facultative anaerobe
what kind of bacteria is nocardia spp.
grampositive, aerobic actinomyces
what bacteria is modified acid fast positive
nocardia spp. takes up acid fast stain to some degree but not as much as mycobacterium
who does nocardia spp. usually infect
immunocompromised patients
what are the clinical presentations of nocardiosis
pulmonary infections, brain abscesses, skin/soft tissue infection
how to treat nocardia spp
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
does actinomyces cause acute or chronic infections
chronic infections, require long term treatment to prevent recurrence
what bacteria can cause chronic canaliculitis
actinomyces
how to treat actinomyces
surgical debridement with antibiotics
what shape is mycobacterium
rod shaped
is mycobacterium gram positive or negative
gram positive
is mycobacterium aerobic or anaerobic
aerobic
what bacteria appears pink on ziehl neelson stain and why
mycobacterium because it is acid fast bacilli and contains mycolic acid in cell wall
what are the main pathogenic strains of mycobacterium. where are non pathogenic strains found
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.
how is tuberculosis transmitted and where does it usually infect
airborne via human to human spread. NOT DROPLET TRANSMISSION!! hence must use n95
pulmonary infection
what percentage of patients gets infected following exposure to m tuberculosis
10%
what are the classical tb symptoms
fever and night sweats, cough with sputum production, weight loss
what type of necrosis is characteristic of tb infection
caseous necrosis
what happens in primary pulmonary tb
ghon focus: spreads to regional lymph nodes, lymph nodes enlarge
granuloma formation in attempt to contatin infection
caseous necrosis
what happens when tb progresses from primary stage
progression of primary lung lesion, pleural effusion
bacteremia. disseminated in blood stream (miliary infection)
what can happen as a result of miliary infection
disseminated tb infection in blood stream can cause organ specific infection mimicking cancer, meningitis, genitourinary tract infection including kidneys
what are the clinical manifestations of oral tuberculosis
non healing chronic ulcers local lymph node enlargement jaw osteomyelitis inflammation abscess
how to diagnose tb
biopsy oral lesion and do afb microscopy and culture
histology for tissue/bopsy specimens afb smear (microscopy), afb culture, molecular testing
what is the downside to afb smear in trying to diagnose mycobacterium tb infection
unable to differentiate between tb and non tb mycobacteria
how long does m tuberculosis culture take to grow
6-8 weeks
what is lowenstein jensen media used for
tuberculosis
how is tuberculosis cultured nowadays
MGIT system, liquid media
automated reading, more sensitive than lowenstein jensen solid media, faster positive results
what is the advantage of using molecular methods to diagnose m tuberculosis
pcr gives same day results and able to differentiate m tuberculosis from other mycobacterium and able to detect rpob gene coding from rifampicin resistance
how are patients treated for tb
if not resistant to rifampicin, multidrug therapy with rifampicin to avoid development of rifampicin resistant TB. extended treatment for 6 months or more
what is time period for statutory notification of tb infection
72 hours
what is the contact screening procedure for tb
tuberculin skin testing, quantiferon gold, t spot, x ray to exclude active disease
how are patients with pan sensitive tuberculosis dealt with
isolated in negative pressure room until deemed non infectious
they become non infectious within 2 weeks of treatment
what does bcg vaccine do
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
what is leprosy caused by
mycobacterium leprae
compare grwoth rates of m tuberculosis, slow growing atypical mycobacterium, rapidly growing atypical mycobacterium
tb 2-3 weeks
slow 4-6 weeks
rapid within 1 week
4 different types of clinical presentation of non tuberculosis mycobacterium infection (more common in immunocompromised)
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
why is repeated isolation of same non tuberculosis mycobacterium necessary to diagnose pulmonary disease caused by atypical mycobacteria
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
how to treat non tb mycobacterium infection
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
