Microbiology Flashcards
1
Q
How would you detect staph aureus?
A
Gram +ve
Catalase +ve = staph
Coagulase +ve
2
Q
Give 3 infections staph aureus causes?
A
Skin infections - cellulitis
Osteomyelitis and septic arthritis
Pneumonia
Endocarditis
3
Q
How would you detect staph epidermidis?
A
Gram +ve
Catalase +ve = staph
Coagulase -ve
4
Q
Give an example of an infection caused by staph epidermidis?
A
Endocarditis on prosthetic valves
5
Q
How would you detect strep pneumoniae?
A
Gram +ve cocci
Catalase -ve = Strep
Alpha haemolytic
Optochin sensitive
6
Q
Give three examples of when you would use amoxicillin?
A
- Strep Pneumoniae (mild)
- With clauvulonic acid in beta lactase resistance or severe pneumonia
- Meningitis >55 and immunocompromised as well as IV cefotaxime
- PPI + Clarithromycin for H.pylori
7
Q
How would you detect strep virdidans?
A
Gram +ve cocci
Catalase -ve = Strep
Alpha haemolytic
Optochin resistant
8
Q
Give an example of an infection caused by strep viridian’s?
A
Endocarditis - rheumatic patients in dental
9
Q
How would you detect strep pyogenes?
A
Gram +ve
Catalase -ve
Beta Haemolytic
Group A lancefield
10
Q
How would you treat strep viridian’s?
A
Benzylpenicillin and gentamycin
11
Q
How would you diagnose listeria monocytogenes?
A
Gram +ve bacilli - aerobic (found in cheese)
12
Q
Give an example 2 infections caused by strep pyogenes?
A
Necrotosing faciatis / cellulitis
Strep throat
13
Q
How would you detect E. coli?
A
Gram -ve bacteria. lactose fermenter, pink on MacConkey
14
Q
What disease does listeria cause?
A
Meningitis in immunocompromised
15
Q
How would you treat listeria?
A
Amoxicillin and gentamicin
16
Q
Give 2 examples of gram -ve cocci?
A
Neisseria meningitides
Neisseria gonorrhoea
17
Q
Which components of MacConkey agar inhibit growth of gram positives?
A
Bile salts and crystal violet
18
Q
How would you detect Klebsiella pneumoniae?
A
Gram -ve bacilli, lactose fermenter, pink on MacConkey
19
Q
How would you treat Klebsiella?
A
Cefotaxime
20
Q
How would you differentiate between E.coli and klebsiella?
A
API strip and sensitivity tests
21
Q
How would you detect haemophilia influenza?
A
Gram -ve cococbaccili
Chocolate agar
22
Q
How would you treat Haemophilus influenza?
A
Cefotaxmine
2nd Line Chlomphenicol
23
Q
Give 2 examples of disease caused by haemophilus influenzae?
A
Meningitis
Pneumonia
24
Q
How do you detect legionella pneumophillia?
A
Gram -ve cococobaccili - urine antigen test
25
How would you detect pseudomonas aurginosa?
Gram -ve bacilli, non-lactose fermentor, oxidative +ve
26
Which two diseases/infections can pseudomonas aurginosa cause?
UTI in catheterised
| Pneumonia - bronchiectasis
27
How would you treat helicobacter pylori?
Omeprazole, amoxicillin and clarithromycin
28
Which virus is detected by presence of inclusion bodies?
Herpes Simplex
29
How do you detect EBV?
Immunoflourecent anti-IgG
30
What is the treatment for glandular fever?
None
31
Name 2 infectitions cause by herpres varicella zoster?
Chicken pox and shingles
32
How do you treat herpes varicella zoster in a) children and b) adults?
Children - calamine
| Adults - Acyclovir
33
How would you detect cytomegalovirus?
Owl eye - inclusion bodies
34
Which agar would you grow candida albicans on?
Sabourad agar
35
How would you detect PCP?
PCR detection
36
Give 3 occasions when you would use metronidazole?
1. C.difficile
2. Appendicitis
3. Giardia Lambia
37
What would you see on microscopy of patient with giardia?
Trophozoites and cysts - travel
38
Give two infections that candida albicans can form?
Thrush
| Endocarditis - immunocompromised with Hickman line
39
How would you detect hepatitis A?
IgM antibody +ve
40
How do you treat chronic Hepatitis B infection?
PEG interferon alpha
41
What is used to assess the risk of complications of infections caused by strep pyogenes?
Anti- SLO titre
| Looking for antibodies against strepyloysin O
42
Give 4 components of the structure of mycobacteria ?
1. Peptidoglycan cell wall
2. Arabinogalactan
3. Mycolic acids form thick waxy coat
4. High molecular weight plasma membrane
43
Give 3 characteristics of fungi?
Exist in yeast or mould form, chitinous cell wall, eukaryotic
44
What are the 6 stages of viral replication?
1. Attachment
2. Cell Entry
3. Interaction with host cells
4. Replication
5. Assembly
6. Release
45
Which 4 antibiotic classes work by inhibiting cell wall synthesis?
Glycopeptides (vancomycin) and the beta lactams which are penicillins, cephalosporins and carbapenems
46
How do penicillins work?
Inhibit beta-lactamases which are responsible for cross-linking peptidoglycan in bacterial cells. This weakens them preventing maintenance of osmotic gradient lead to cells death.
47
What are the 2 uses of trimethoprim and how does it work?
UTI (1st line-uncomplicated)
Combined as Co-trimaxole for PCP
Inhibits folate acid synthesis and thus DNA synthesis
48
How do Quinolones (eg ciproflaxcin) work?
Inhibit DNA gyrase which helps DNA to fold
49
What is a bacteriostatic antibiotic?
Stop bacteria growth and replication but do not kill them instantly
50
What is a bacteriocidal antibiotic?
Directly kills the bacteria
51
When are bactericidal antibiotics useful?
Poor penetration eg endocarditis
Difficult to treat infections eg TB
Need to eradicate infection quickly eg meningitis
52
How do bacteria develop acquired resistance?
1. Spontaneous gene mutation
| 2. Horizontal gener transfer - conjugation, transduction and transformation
53
Other than MRSA give an example of gram positive bacteria that exhibits resistance?
Vancomycin resistant enterococci
54
Which 4 classes of drugs inhibit protein synthesis in bacteria?
Amazing Claire Marie Trudgian
| Aminoglycasides, chloramphenicol, macrocodes, tetracyclines
55
What class of drug is vancomycin and when is it used?
Glycopeptides - Used in treatment of severe C.difficile and MRSA
56
Give 2 examples of a serology technique?
1. Complement fixation test
| 2. ELISA - enzyme linked immunosorbent assays
57
When would you use chocolate agar?
Neisseria and H.influezea
58
When would you used CLED agar?
Use to differentiate micro-organisms in urine
59
What colour is a non-lactose fermentor on MacConkey agar?
yellow
60
When is XLD agar used?
Selective growth medium to isolate growth of salmonella and shigella
61
What colour is Salmonella on XLD agar?
Yellow and shigella remains red
62
What are 4 of the key principles for taking blood cultures?
1. Take blood culture before giving antibiotics
2. Take good volumes
3. Take from more than one site
4. Take on more than one occasion
63
What colour is a viral swab?
Green
64
What is a disadvantage of PCR use?
Vulnerable to contamination and may give false positive
65
When is electron microscopy useful for diagnosing viruses?
When new virus appears
66
What is the supportive management of glandular fever?
Supportive therapy and avoid contact sport for at least 6 weeks
67
In a patient with suspected Influenza what should you do whilst awaiting results of PCR?
Isolate patient and treat with neuroaminidase inhibitors
68
How can you detect if it is a primary disease or reactivation?
IgG remains for life and will rise in re-infection
| IgM detects acute infection
69
What are the steps in performing a gram stain?
1.Apply crystal violet, apply iodine and wash with acetone
70
Name 4 sterile sites of the body?
Gallbladder, kidney, lungs, pleural fluid and blood
71
Which special stain identifies corynebacterium diphtheria?
Methylene blue
72
Which organism shows draughtsman colonies on blood culture?
Strep pneumoniae
73
Which genetic condition is a predisposition for pseudomonas infections?
Cystic fibrosis - excess secretions provide environment for bacterial growth
74
Which selective media can you culture mycobacterium in?
Lowestein-Jenson
75
Name 3 components of a virus?
1. Nucleic acid core
2. Lipid envelope
3. Protein caspid
4. Spike projections - cell receptors
76
Give 3 investigations of TB?
Sputum (x3), Induce sputum, broncho-alveolar lavage, tissue sample
77
What is meant by dysentry?
Inflammatory disorder of GI tract, often associated wutg blood and pus in faeces and accompanied by symptoms of pain, fever, abdominal cramps
78
Give 3 investigations of UTI?
Mid-stream urine, direct microscopy and culture
79
Give 3 viral causes of meningitis?
Mumps, echo virus, coxsackie virus, herpes simplex virus
80
How would you treat legionella causing pneumonia?
Clarithromycin
81
Which antibiotics would you use to treat strep pyogenes?
Benzylpenicillin
82
Name a severe fungal infection of the eye?
Endothalmitis - severe fingal infection of vitreous humour in the eye
83
How can you further differentiate salmonella?
Kauffman-white scheme - according to presence of different O and H surface antigens
84
Which antibiotic do you use to treat enterococcus?
Amoxicillin and gentamicin
85
How do you treat endocarditis caused by strep viridian's?
Gentamicin and benzylpeniciilin
86
Which three drugs do you use to treat HIV?
2 nucleotide reverse transcriptase inhibitors and 1 non-nucleotide reverse transcriptase inhibitor or protease inhibitor
87
Which medium cultures campylobacter?
CCDA
88
Give a treatment method for helminths eg schistosomiasis?
Praziquentel
89
What are the 3 generations of cephalosporins?
1. Cephlaxen
2. Cefuroxime
3. Ceftriaxone
90
Name 3 broad spectrum antibiotics?
1. Cephalosporins
2. Carbapenems
3. Tetracyclines (Doxycycline )
91
Give two uses of cephalosporins?
Surgical prophylaxis, Meningitis (1st line)
92
Give an example of when you would use carbapenems eg Imipenem?
Treatment of severe/complicated or drug resistance infections
93
Give 3 occasions when you would use a macrolide eg erythromycin?
1. Atypical pneumonia + penicillin
2. Penicillin allergies eg cellulitis
3. For H.pylori in peptic ulcer disease with PPI + amoxicillin
94
What is the mechanism of macrolides?
Bind to 50s subunit on ribosome so ribosome can't produce protein
95
Give 3 examples of when you would use doxycycline?
Acne vulagaris, chlamydia, malaria, pelvic inflammatory disease and chronic bronchitis
96
How do tetracyclines work?
Bind to 30S subunit on ribosomes to tRNA can't bind to mRNA so no polypeptide formation
97
Give 2 examples when you would use gentamicin?
```
Infective endocarditis (with benzylpenicillin) - synergistic
Pyelonephritis and complicated UTI
```
98
Which 4 antibiotics work by inhibiting nucleic acid synthesis?
Trimethroprim, quinolines, metranidazole, rifampicin
99
Give 3 occasions when you would use quinolines eg ciprofloxacin?
2nd line UTI
Cystic fibrosis (vulnerable to pseudomonas - common in cf)
Severe GI infections
100
How does rifampicin work?
Binds to RNA polymerase, this stops its synthesis from mRNA so bacteria can't grow
101
Which antibiotic works for infections caused by anaerobes?
Metronidazole
102
Describe the 3 methods of horizontal gene transfer in acquiring antibiotic resistance?
1. Conjugation - transfer plasmid via sex pillus
2. Transduction - DNA packaged into viral particle and transferred
3. Transformation - take up free DNA from environment
103
How can bacteria be resistance to antibiotics?
1. Change antibiotic target
2. Destroy the antibiotic
3. Prevent antibiotic access
4. Remove antibiotic from bacteria
