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Clinical Pathology > Advanced Microbiology > Flashcards

Advanced Microbiology Flashcards

1
Q

investigation for meningitis

A

lumbar puncture
blood cultures x2
blood for bacterial PCR - S.pneumoniae and N.meningitidis

Immunosuppressed: cryptococcal antigen, TB culture/ PCR

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2
Q

investigation for encephalitis

A

CSF viral PCR

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3
Q

investigation for brain abscess

A

local sampling of pus
gram, culture, sensitivity
blood cultures

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4
Q

investigation for acute otitis media

A

clinical diagnosis
viral and bacterial
send pus if ear drum perforated

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5
Q

investigation for acute otitis externa

A

ear swab

determine cause and sensitivity

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6
Q

investigation for rhino-sinusitis

A

majority viral
2nd bacterial infection
severe cases: pus from operative sinus lavage
FBC, blood cultures

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7
Q

investigation for pharyngitis

A

most viral
throat swabs if evidence of bacterial infection
B-haem-strep
EVB serology, diptheria swab, pus if quinsy abscess

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8
Q

investigation for influenza

A

test those who may require treatment

PCR has sens>90% and spec >99%

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9
Q

investigation for pneumonia

A

CURB65
0-1 no investigations
2-5 - sputum, blood cultures, atypical screen

atypical screen: legionella antigen, nose/throat for mycoplasma PCR, might include serum

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10
Q

investigation for TB

A

exposure testing: mantoux, IGRA, rely on intact immune system

Pulmonary symptoms: 3 sputum samples
microscopy and culture
PCR - rapid, costly, lower sensitivity

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11
Q

investigation for atypical infections

A

PCR for viral/ pneumocytosis

cultures for fungal e.g. aspergillus

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12
Q

investigation for localised skin infection

A

blister fluid/ abscess puss
needle aspirates from cellulitis
blood cultures - send if sepsis

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13
Q

investigation for necrotising fasciitis

A

debrided tissue - pus
2 sets blood cultures
bloods - FBC, U&Es, LFTs, CRP

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14
Q

investigation for diabetic foot

A

mild infection: wound swabs

mod/severe infection - debride wound then clean bone/ tissue sample

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15
Q

investigation for cystitis/ pyelonephritis

A

urine sample: WBC, RBC, epithelial cells, bacterial growth, sensitivities

Kass criteria: significant bacteruria

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16
Q

investigation for prostatitis

A

urinalysis

post prostatic massage

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17
Q

investigation for epididymo-orchiditis

A

either enteric/UTI or STI
urine sent for cultures
urine - chylamydia and gonorrhoea

severe: bloods, blood cultures, USS +/- drainage

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18
Q

investigation for infectious diarrhoea

A 
lab guiding with clinical details 
stool sample x3 for parasites 
bloods: FBC, clotting, U&Es, LFTs, CRP
blood cultures
abdominal imaging
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19
Q

investigation for H. pylori

A 
H. pylori antibody test 
H. Pylori stool antigen 
urea breath test - gold standard for test of sure 
biopsy urease test 
stop PPIs before testing
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20
Q

investigation for liver abscess

A

pyogenic (bacterial), hyatid or amoebic

pus if safe to frain 
stool for OCP 
blood cultures
FBC, U&Es, LFTs CRP
hydatid serology 
USS/CT
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21
Q

investigation for cholangitis/ cholecystitis

A

FBC, U&E, LFT, blood cultures, clotting, amylase, USS/CT, bile fluid/ pus

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22
Q

investigation for diverticulitis

A

pus
blood cultures
FBC, U&E, LFT, clotting, amylase, CT

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23
Q

investigation for endocarditis

A

blood cultures
3 sets taken at different times during first 24 hrs
echocardiography - trans-thoracic echo, trans-oesophageal echo (done for suspected PVE)
FBC, CRP, U&E, LFTs
bartonella, chylamydia, coxiella, brucella serology
valve tissue if valve replaced

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24
Q

investigation for vascular graft infection

A

3 sets blood cultures in 1st 24 hrs
CT, PET, WBC scan - fluid around graft, fistulae
tissue/fluid from around the graft for culture or PCR

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25
investigation for viral hepatitis
serology +/- PCR antigen and antibody detection PCR detects DNA or RNA from living/dead organisms suggests active infection
26
investigation for syphilis
PCR | serology - IgM in primary infection, treponemal specific antibody, non-treponemal specific antibody
27
bacterial cell wall inhibitors
B-lactams | glycopeptides
28
antifungal cell wall inhibitors
echinocandins
29
structure of B-lactams
CCCN ring structure
30
B-lactam mechanism of action
interfere with function of penicillin binding proteins - transpeptidase enzymes involved in peptidoglycan cross-linking
31
first true antibiotic in clinical practice
benzyl penicillin
32
B-lactam antibiotics
penicillins Cephalosporins Carbapenems Monobactams
33
examples of penicillins
benzylpenicillin, amoxicillin, flucloxacillin - narrow spectrum
34
examples of cephalosporins
cefuroxime, ceftadime - broad specrum - arranged into generations
35
examples of carbapenems
meropenem, imipenem | - extremely broad spectrum
36
examples of monobactams
aztreonam | - gram-negative activity only
37
common mechanism of resistance to b-lactams
B-lactamase enzymes
38
which b-lactams are staphylococcal b-lactamase resistant to
some penicillins only
39
which b-lactams are extended spectrum b-lactamase resistant to
penicillins and cephalosporins
40
which b-lactams are carbapenemases resistant to
carbapenems
41
what are BLBLI
b-lactam/b-lactamase inhibitor combinations
42
what is co-amoxiclav
amoxicillin and clavulanic acid | gram -ve, anaerobes
43
what is tazocin
piperacillin-tazobactam anti-pseudomonal, staph, strep, enterococci, anaerobes, pseudomonas, gram -ve greatly increase spectrum = risk of c.diff
44
mechanism of action of glycopeptides
large molecules bind directly to terminal D-ananyl-D-alanine on NAM pentapeptides inhibit linking of transpeptidases and thus peptoglycan cross linking
45
what bacteria do glycopeptides target
gram +ve
46
examples of glycopeptides
vancomycin, teicoplanin
47
different protein synthesis inhibitors
aminoglycosides macrolides, lincosamides tetracyclines oxazolidones
48
examples of aminoglycosides
gentamicin, amikacin
49
mechanism of action of aminoglycosides
bind to 30S subunit
50
examples of macrolides
erythromycin, clarythromicin
51
example and mechanism of action of a Lincosamide
clindamycin bind to 50S subunit inhibit protein elongation
52
mechanism of action of tetracycline
bind to 30S subunit | inhibit translation by interfering with binding tRNA to rRNA
53
examples of tetracyclines
tetracycline, doxycycline, tigecycline - modern derivative with a similar mechanism of action and much broader spectrum
54
mechanism of action of oxalidinones and example
linezolid inhibits initiation of protein synthesis binds to 50S ribosomal subunit inhibits assembly of initiation complex
55
mechanism of action of echinocandins (antifungal)
inhibition of B-1,3-glucan synthase | construction of severly abnormal cell wall
56
examples of echinocandins
anidulafungin caspofungin micafungin
57
examples of DNA synthesis inhibitors
trimethoprim and sulfonamides
58
mechanism of action of DNA synthesis inhibitors
inhibit folate sythesis trimethoprim - dihydropteroate synthetase sulfonamides - dihydropteroate synthesis
59
mechanism of action of quinolones and fluoroquinolones
inhibit one or more of two related bacterial enxymes - DNA gyrase and topoisomerase IV which is involved in remodelling DNA in DNA replication
60
examples of quinolones
nalidixic acid, ciprofloxacin, levofloxacin
61
mechanism of RNA synthesis inhibitors
RNA polymerase inhibitor | prevents synthesis of mRNA
62
examples of RNA synthesis inhibitors
Rifampicin
63
mechanism of action of Terbafine
inhibit synthesis of ergosteroll
64
mechanism of action of amphotericin B
bind to ergesterol and cause physical damage to the membrane
65
virus syndromes that cause non-vesicular rashes
``` measles rubella parvovirus adenovirus HHV6 ```
66
virus syndromes - vesicular rashes
chicken pox herpes simplex enterovirus
67
when would you use antivirals
``` acute infections in general population - primary HSV and HS encephalitis - chickenpox in adolescents and adults - shingles in eye - elderly chronic infections infections in immunocompromised ```
68
mechanism of action of nucleoside reverse transcriptase inhibitors
inhibit reverse transcriptase
69
NRTIs used in HIV
azidothymine thymine analogues - zidovudine cytosine analogues - lamivudine purine analogues - abacavir, tenofovir
70
NNRTIs
efavirenz | neviparine
71
what is HAART
highly active antiviral therapy 2NRTIs + NNTRI 2NRTIs + boosted PI (protease inhibitor) boosted when CD4 count falls
72
indications for aciclovir
HSV, VZV
73
mechanism of action of aciclovir
inhibit herpes DNA polymerase
74
administration of aciclovir
topically, IV, orally
75
what is valacyclovir
prodrug converted to acyclovir - prevents CMV following organ transplantation
76
indication for osteltamivir
Influenza A or B
77
mechanism of action of osteltamivir
neuramidase enzyme cleaves sialic acid on glycoproteins allowing virions to exit
78
treatment for CMV
ganciclovir
79
indication for ribavirin
RSV, HCV, HEV
80
leucocyte esterase meaning
enzyme produced by neutrophils WBCs anywhere in GU tract +ve - chylamydia, urethritis, TB, bladder tumours, viral infections, nephroliasis, foreign bodies and corticosteroid use
81
nitrites meaning
some bacteria nitrates>nitrities +ve means infection some organisms do not reduce nitrates
82
Urine dip RBC
peroxidase activity of erythrocytes | high doses of Vit C can produce false negative
83
bacterial pathogens of lower UTI
enterobacteriaciae - GI organisms - E.coli, proteus, klebsiella Enterococci - GI organisms Staphylococci - S.aureus streptococci - aHS, bHS
84
common antibiotics for lower UTI
``` Trimethoprim Nitrofurantoin Amoxicillin (piv)mecillinam fosfomycin cephalosporins, cirpfloxacin ```
85
nitrofurantoin
therapeutic levels only achieved in urine treatment of simple, uncomplicated UTI can be given in pregnancy
86
(piv)mecillinam
oral pro-drug of mecillinam relatively stable to bacterial beta-lactamases, including ESBLs active against range of coliform organisms pseudomonas not susceptible no Gram +ve activity e.g. enterococci lower UTI
87
antibiotics suitable for upper UTI due to E.coli
``` cefuroxime azteronam - used in case piperacillin-taxobactam ciprofloxacin gentamicin ```
88
innate resistance mechanism
fundamental property of the bacterium/antibiotic combination
89
what antibiotics are gram-negatives resistant to?
glycopeptides, daptomycin
90
what antibiotics are gram-positives resistant to?
aztreonam, colistin
91
what antibiotics are anaerobes resistant to?
aminoglycosides
92
what antibiotics are streptococci resistant to?
aminoglycosides
93
acquired resistance mechanism
acquisition of a gene that encodes an antibiotic resistance mechanism - new mutation - horizontal transfer
94
mechanisms of antibiotic resistance
1. absent target 2. decreased permeability 3. target modification 4. enzymatic degradation 5. drug efflux
95
absent target examples
antibacterial agents/fungi | antiviral agents/bacteria
96
decreased permeability examples
Vancomycin: gram -ve bacilli - gram negatives have outer membrane that is impermeable to vancomycin Gentamycin: anaerobes uptake of aminoglycosides requires an O2 dependent AT mechanism
97
target modification examples
flucloxacillin: MRSA - altered penicillin binding protein does not bind B-lactams Vancomycin: VRE - altered peptide sequence in gram + peptidoglycan reduces binding of vancomycin Trimethoprim: Gram -ve bacilli - mutations in dhr
98
enzymic degradation examples
penicillins and cephalosporins: B-lactamses - staphylococcal penicillinase - extended spectrum B-lactamases - carbapenems Gentamycin: aminoglycoside modifying enzymes Chloramphenicol: chloramphenicol acetyltransferase (CAT)
99
drug efflux examples
multiple antibiotics - Gram -ve
100
development of resistance
encoded by single genes resistance genes in plasmids - conjugation - horizontal transfer - transposons and integrons - vertical transfer - chromosomal or plasmid-borne resistance genes transferred to daughter cells
101
gram positive cocci
staph, strep
102
gram neg cocci
meningococcus, gonococcus
103
gram positive bacilli
cornyebacterium listeria clostridium
104
gram negative bacilli
enterobactericeae - e. coli - proteus - klebsiella - enterobacter
105
what is penicillin G
benzylpenicillin iv/im
106
what is penicillin V
phenoxymethylpenicillin
107
spectrum of penicillin G and V
narrow-spectrum streptococci - s. pneumoniae, s. pyogenes many anaerobes some GNC e.g. N.meningitidis
108
flucloxacillin spectrum
broader than pen G not destroyed by staphylococcal B-lactamase staphyloccoci few GNC, anaerobes, streptococci
109
amoxicillin spectrum
``` as for pen G but broader some GNB most enterococci strep, entero destroyed by b-lactamase ```
110
co-amoxiclav spectrum
``` broad pen G/V e.g. strep flucloxacillin e.g. staph amoxicillin - most ECOC many GNB many anaerobes increased c.diff risk ```
111
tazocin
piperacillin-tazobactam
112
tazocin spectrum
piperacillin - more GNB than amoxicillin anti-pseudomonal activity broad-spectrum -staph, strep, enterococci, anaerobes, pseudomonas sp. GN organisms
113
marcolides
erythromycin, clarithromycin, azithromycin
114
spectrum of macrolides
most gram pos intracellular organisms e.g. mycoplasma, chlamydia, legionella - atypical limited gram neg
115
glycopeptides
``` vancomycin, teicoplanin iv gram + staph, strep, entero non-b-lactam vancomycin - renal ```
116
clindomycin
``` po/iv gram + organisms staphylococci, streptococci, anaerobes anti-toxin action good tissue penetration associated with Cdiff ```
117
fluoroquinolones
oral/iv non-b-lactam associated with CDI intracellular
118
fluorquinones - ciprofloxacin
gram - anti-pseudomonas staph, atypicals poor strep/anaerobe
119
fluorquinones - levofloxacin
gram + strep, atypicals resp FQ less GN, pseudomonas
120
aminoglycosides
``` gentamicin gram - bacilli inc pseudomonas staph poor strep no anaerobes nephro/ototoxicity ```
121
metronidazole
oral/iv bacteria - anaerobes parasites - protoza, helminths
122
oral options of MRSA
clarithromycin clindamycin doxycycline trimethoprim/co-trimoxazole

Clinical Pathology (8 decks)

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