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Cardiovascular > Cardiac Infections + Microbiology Revision > Flashcards

Cardiac Infections + Microbiology Revision Flashcards

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1
Q

what is bacteraemia

A

presence of bacteria in the bloodstream

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2
Q

is blood usually sterile

A

yes

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3
Q

what could happen if bacteraemia is not treated

A

patient could go into septic shock and die

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4
Q

why is it important to have sterile techniques when taken blood cultures

A

to avoid contamination and false negatives

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5
Q

what is the difference between a positive and negative blood culture bottle

A

different colours, positive infected with organism

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6
Q

what should you not start antibiotics without

A

evidence of bacterial infection

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7
Q

what is infective endocarditis

A

infection of the endothelium of the heart valves

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8
Q

what are the types of onsets of infective endocarditis

A

acute or subacute

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9
Q

what are the predisposing factors of IE

A

heart valve abnormality, prosthetic heart valve, intravenous drug users, patients with IV lines

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10
Q

what are three types of heart valve abnormalities and why do they predispose IE

A

calcification/ sclerosis in elderly,
congenital heart disease,
post rheumatic fever

creates turbulent blood flow which causes endothelial injury, inflammation, bacteria adhere to inflamed sites

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11
Q

why does a prosthetic valve predispose a patient to IE

A

as bio films grow over them

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12
Q

describe the pathogenesis of endocarditis

A

heart valve damaged- turbulent blood flow over roughened endothelium- platelets/ fibrin deposited, bacteraemia (may be transient e.g. from dental work)- organisms settle in fibrin/ platelet thrombi becoming a microbial vegetation

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13
Q

which side of the heart is most likely affected with IE

A

left side of heart- mitral and aortic valves

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14
Q

why do infected vegetations pose such a risk

A

as they are friable and easily break off, can lodge in next capillary bed causing abscesses or haemorrhage

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15
Q

what can dislodges infected vegetations cause if they travel distally

A

gangrene/ septic emboli

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16
Q

what are the most common causative agents of IE, commonest first

A

staphylococcus aureus,
viridans streptococci,
enterococcus sp,
staph epidermidis

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17
Q

what atypical organisms can cause endocarditis

A

bartonella, coxiella burnetii (Q-fever) (in farm animal poo), chlamydia, legionella, mycoplasma, brucella

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18
Q

how are atypical organisms detected

A

cant be grown on blood culture but detected via serology- looking for antibodies

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19
Q

what gram negative organisms can cause endocarditis and how are the detected

A

HACEK organisms and non HACEK organisms

HACEK= can be detected in blood cultures but need to be help for 7-10 days

(HACEK; Haemophilus spp., cardiobacterium etc)

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20
Q

along with atypical and gram negatives, what other unusual organism can cause IE

A

fungi

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21
Q

what are the major criteria in dukes criteria for diagnosis endocaritis

A

two separate pos blood cultures with microorganisms typical for IE

echocardiographic evidence of endocardial involvement

typical valvular lesions: vegetations, abscess or surgical wound rupture of a prosthetic valve

new valvular regurgitation

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22
Q

what organisms are typical for IE

A

staphylococcus aureus, viridans streptococci, community acquired enterococci, streptococci bovis, HACEK group

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23
Q

what are the minor criteria of duke criteria

A

predisposition, temp >38, vascular or immunological phenomena, micro-bacterial evidence

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24
Q

what non immunological investigations are done to diagnose IE

A

transthoracic echocardiography and (not always necessary) transoesophageal echocardiography

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25
gram positive cocci in clusters=
staph
26
gram pos cocci in chains =
strep
27
what antibiotics for staph infections
penicillins
28
what are lancefield group a antigens
molecules on surface of strep
29
describe the coagulase test
used to differentiate Staphylococcus aureus (positive) from Coagulase Negative Staphylococcus (CONS). identifies whether an organism produces the exoenzyme coagulase, which causes the fibrin of blood plasma to clot Staphylococcus aureus produces free coagulase; Staphylococcus epidermidis does not.
30
what is the most common coagulase negative staphylococcus
staphylococcus epidermidis
31
what is the usual habitat of staph epidermidis
often a skin contaminant but can infect prosthetic material
32
what does staph aureus look like
gram pos, in clumps, golden on blood agar (beta haemolysis)
33
what are the three types of haemolysis
alpha- green discolouration surrounding colony= partial decomposition of haemoglobin beta- complete break down, clearing of agar around the colony gamma- no breakdown, brownish discolouration
34
what other mechanisms can be used to identify microorganisms
mass spectrometer (peptides, amplification of DNA), agar culture, serology, PCR
35
what should be done if a patient has a positive result for staph aureus in the blood
if possible remove IV device, think if there is an IV source, asses severity and source before giving antibiotics
36
what are the presenting symptoms of acute endocarditis
overwhelming sepsis and cardiac failure
37
what are the symptoms of subacute endocarditis
fever, malaise, weight loss, tiredness, breathlessness
38
what are the clinical signs of subacute endocarditis
fever, new/changing heart murmur, finger clubbing, splinter haemorrhages, splenomegaly, roth spots, osler nodes, janeway lesions, microscopic haematuria
39
what are roth spots
retinal haemorrhages with white or red centres
40
what are janeway lesions
non-tender, small erythematous or haemorrhagic macular or nodular lesions on the palms or soles
41
what are osler nodes
painful, red, raised lesions found on the hands and feet (osler ouch)
42
what type of haemolysis does strep viridans cause
alpha
43
what type of endocarditis does strep viridans cause
subacute
44
where are strep viridans found
normal oral commensals
45
are there lacefield group on viridans
no
46
why is it important to take 3 sets of blood cultures
to determine between a causative agent and a contaminant
47
why are infections caused by atypical organisms harder to treat
as harder to identify causative organism and tailor antibiotics
48
which is the first echocardiography to be performed
transthoracic
49
when should a transoesophageal echocardiography be performed
- prosthetic valve or intracardiac device - positive for infective endocarditis - non-diagnostic images - negative for IE but high clinical suspicion
50
when does the infection in early prosthetic valve endocarditis usually occur
at time of valve insertion (until following 60 days)
51
what is usually the causative agent in early prosthetic valve endocarditis
staph aureus or epidermidis
52
when does late prosthetic valve endocarditis occur and due to what
up to many years after valve insertion, due to co-incidental bacteraemia
53
what should all patients with prosthetic valves be given
vancomycin + gentamycin+ (later after other two have worked a bit) rifampicin
54
what are the complications of IE
cerebral emboli, roth spots, haemorrhages, murmurs, conduction disorders, cardiac failure, systemic emboli, loss of pulses, clubbing, splinter haemorrhages, janeway lesions, oslers nodes, splenomegaly, hematuria
55
what part of heart is most commonly affected by IE in PWIDs
right side- tricuspid valve
56
what organism is common in IE in PWIDs
staph aureus
57
how is native valve endocarditis treated and what is it called by
viridans strep amoxicillin and gentamicin (IV)
58
what happens when amoxicillin and gentamicin are used together
synergistic effect
59
how is prosthetic valve endocarditis treated
Vancomycin & gentamicin IV Add in day 3 to 5 (delayed) rifampicin PO valve replacement often required
60
what ids rifampicin good at getting rid of
biofilm
61
how is drug user endocarditis treated (MSSA)
flucloxacillin IV
62
what is staph aureus IE treated (not MSSA)
flucloxacillin IV
63
how is viridans streptococci IE treated
Benzylpenicillin iv & gentamicin iv (synergistic)
64
how is enterococcus sp. treated
Amoxicillin/ vancomycin & gentamicin IV
65
how is staph epidermidis treated
Vancomycin & gentamicin IV & rifampicin PO
66
describe the monitoring of treatment in IE and how long it usually lasts
IV antibiotics for 4-6 weeks monitor cardiac function, temperature, serum -reactive protein if failing consider surgery
67
what worsen the prognosis of IE
patient characteristics: age, prosthetic valve, diabetes mellitus, co-morbidity clinical complications of IE: heart failure, renal failure, ischaemic stroke, brain haemorrhage, septic shock microorganism: staph aureus, fungi, non HACEK gram neg bacilli (bad ones) echocardiographic findings: pulmonary hypertension, severe valve dysfunction, large vegetations, low LV ejection factor,
68
when in IE should urgent surgery be taken out in stead of medical management
severe heart failure (and HF with severe vale regurgitation), high embolic risk with other poor prognostic values, persistent sepsis
69
when in IE can elective surgery be taken out in stead of medical management
HF with severe vale regurgitation, high embolic risk with no nother prognostic values,
70
in what group of people is myocarditis common and what does it result in
in young people (cause of sudden death)
71
what are the symptoms of myocarditis
fever, chest pain, shortness of breath, palpitations
72
what are the signs of myocarditis
arrhythmia, cardiac failure
73
what is myocarditis
inflammation of the cardiac muscle
74
what is myocarditis mainly caused by
enteroviruses- Coxsackie A and B, echovirus
75
how is myocarditis diagnosed
viral PCR- throat swab and stool for enteroviruses, throat swab for influenza
76
what else can cause myocarditis
non infectious agents (toxins, hypersensitivity, immunological syndromes) infectious aetiologies (viruses, parasites, bacteria, fungal, protozones)
77
what causes the inflammation of the myocardium in myocarditis
the body's immune response (innate and acquired)
78
what is pericarditis
inflammation of the pericarditis
79
what is the main feature of pericarditis
chest pain- often when breathing
80
what are the common causes of pericarditis
viruses, bacteria (less common), mycoplasma, fungal, parasitic (post cardiothoracic surgery, rarely secondary spread from endocarditis or pneumonia) non infectious (neoplasm, idiopathic, MI, hyperthyroidism) drug induced trauma related
81
what is the treatment for pericarditis
antibiotics and drainage
82
what is night sweats a key word for
TB
83
what organism causes Q fever
coxiella burnetti
84
what is coagulase
a bacterial enzyme which brings about the coagulation of blood or plasma and is produced by disease-causing forms of staphylococcus

Cardiovascular (34 decks)

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