Microbiology: Systemic Bacteriology Flashcards
1
Q
how are micro-organisms classified
A
- appearance
- growth requirements
- enzyme/metabolic tests
- molecular tests
2
Q
how are micro-organisms classified on their appearance
A
shape, size, structure, cell wall (gm-ve/+ve), arrangement
3
Q
how are organisms classified on their growth requirements
A
- aerobic/anaerobic
- requirements for blood proteins
- sensitivity to inhibitory agents
4
Q
what enzyme/metabolic tests can be carried out on a micro-organism
A
- coagulase test
- haemolysis
- catalase test
- biochem profiling
5
Q
what molecular tests can be carried out on a micro-organism
A
- DNA sequencing
- protein profiling
- immunological tests
6
Q
what microscopic identifications are used
A
- staining (gm stains, Ziehl Neilson, fluorochromes)
- structures
- shape, group, sizing
- pure culture or polymorph
7
Q
what are the common shapes of bacterial structures and their names
A
- cocci - spheres
- bacilli - rods
- spiral-shaped
8
Q
what is the division plane of diplococcus
A
1 plane, 2 spheres
9
Q
what is the division plane of sterptococcus
A
1 plane into chains
10
Q
what is the division plane of staphylococcus
A
3 planes, clumps
11
Q
what do bacillus duplicate into
A
chains
12
Q
what are bacillus called
A
vibrio
13
Q
are vibrio gm -ve or gm +ve
A
gm -ve
14
Q
what are the two types of spiral shaped bacteria
A
- spirillum, rigid
- spirochaete, flexible
15
Q
what are spores resistant to
A
chemical and physical challenge
16
Q
what are spores
A
condensed DNA encased in a shall with no active protein processes
17
Q
describe how spores react to antibiotics
A
they dont
18
Q
what colour stain does
- gm -ve
- gm +ve
bacteria go
A
+ve - purple
-ve - pink
19
Q
what organisms dont stain well with gm stain
A
myobacterium TB and treponema pallidum
20
Q
what are the growth requirements of - aerobic - obligate aerobes - obligate anaerobes - facultative anaerobes - capnophilic organisms
A
- grow in O2
- need O2
- killed by O2
- tolerate O2
- prefer high CO2 levels
21
Q
what is selective media
A
media that selects the growth of different bacteria with the presence of specific substances permitting the growth of one organism over another
22
Q
what is differential media
A
media that has chemicals incorporated that produces visible changes in colonies that allow identification
23
Q
describe the different types of haemolysis
A
- alpha, partial - greening
- beta, full - yellow
- gamma, none
24
Q
what is metabolic profiling
A
utilisation of carbon/amino acids
25
what does a coagulase test look for and what bacterium
clot plasma
| - S. Aureus gm+ve
26
what does a catalse test for
the H2O2 -> 2H2O + O2
27
what bacterium does a lipid hydrolysis test look for
clostrida species
28
what reaction does a urease test look for
urea -> ammonia + CO2
29
what do serological tests look for
host immune response and antibodies (i.e. presence of a specific IgM ab)
30
what can serological tests detect
- rapid virus detection
| - specific bacteria serotypes
31
what types of DNA technology is available
- PCR
- ribosome 16S RNA
- MLST
- MALDITOF
32
what is MLST
multi-licus sequence typing - genome sequencing
33
what is MALDITOF
matrix-assoc. laser desorption ionisation time of flight - mass spec
34
what does MALDITOF do
detects spectrum of proteins from samples
35
what bacterium is MALDITOF bad for
staphylococci and streptococci
36
what microbio tests are available
- pus swab
- mucous sample
- blood/urine/faeces culture
- bloods
37
what are exogenous bacteria
not part of normal flora
38
describe the parasitic life cycle
- pathogen enters host from reservoir of pathogens or by host via direct contact
- the parasite the colonies and invades, evading host defences, it multiplies/completes its life cycle and exits host after causing damage
- it then is spread going into reservoir or directly into host
39
virulence
capacity of pathogen to cause damage
40
pathogen
harmful organisms that causes pathology
41
commensal/mutualism/symbiotic
endogenous organism thats part of normal flora, often mutualistic
42
opportunistic pathogen
organism that causes infection when opportunity/change in natural immunity arises
43
contaminant
organism accidentally grown in culture
44
in what type of people do fungal infections occur
immunocompromised
45
what type of diseases to protozoans cause
malaria, GI infections, toxoplasma
46
what are the 2 types of pathogenic gm-ve diplococci
- Neisseria meningitis
| - Neisseria gonorrhoea
47
what pathogenic bacteria are associated with the GI tract
- salmonella
- shigella
- VTEC producing E.coli -0157, 0104
48
what commensal bacteria are associated with the GI tract
- most E. coli forms
- klebsiellla
- enterobacteria
- proteus
49
coliforms
gm-ve bacilli that look like E.coli on gm film and blood cultures
50
in what sort of environment do coliforms best grow
aerobically but can grow anaerobically
51
how are coliforms differentiated
- biochem reactions
- serotyping
- O antigens
- H antigen
52
how can coliforms cause infection
by getting into naturally sterile site
53
what antibiotic is 1st line for coliform infection
gentamicin
54
how is coliform sepsis very bad
endotoxin is released from cell wall when the bacteria die
55
how do endotoxins produce a response
bind to receptors on macrophages, B cells and others stimulating acute cytokine release
56
describe an endotoxin membrane
gm -ve and assymetrical with LPS
57
describe fever production
- endotoxon antigen or LPS interacts with macrophages
- cytokines released
- cytokines travel to anterior hypothalmus
- PGE released and body thermal set point increased
- body initiates cold response
- fever
- increased infection survival
58
what do cytokines stimulate, other than fever, in hypothlmus
adverse effects of sepsis
59
how can harm arise from a fever
febrile convulsions in children
60
what is sepsis
host response to severe infection
61
describe the mechanism behind sepsis
- leaky blood vessels allow fluid to be lose to tissues
- HR increased due to decreased blood vol to
- poor tissue perfusion results in blood supply to less vital organs shutting down to maintain brain blood supply
- clotting cascade activated causing clots in tiny blood vessels
62
how can sepsis increase haemorrhage risk
clotting factors are used up therefore less can be usedin caseof haemorrhage
63
4 gm +ve pathogens
- streptococci
- staphylococcus
- enterococcus
- clostridia
64
what type of bacteria are differentiated using haemolysis
sterpotococci
65
```
describe
- alpha
- beta
- gamma
haemolysis
```
- partial haemolysis, greenish discolouration, Hb in RBCs denatures
- complete haemolysis, yellow, complete lysis of Hb in RBCs
- none
66
what type of streptococci (in terms of haemolysis) is the most pathogenic
beta
67
GAS
group A streptococci
68
what type of haemolysis do GAS undergo
beta
69
infections associated with GAS
- strep pyrogens
- strep sore throat (scarlet fever)
- invasive disease - necrotising fascitis
- peurperal sepsis
70
describe strep pneumoniaes differentiating features
- gm +ve
- alpha haemolytic
- short chains or pairs
71
what bacteria is the most common cause of pneumonia and what else can this bacteria cause
- streptococcal pneumoniae
| - severe meningitis
72
what group of non-haemolytci streptococci are the most important
enterococci
73
what is the most common cause of UTIs
non-haemolytic streptococci
74
what are VREs and where do they break out
- vancomycin-resistant enterococci
| - outbreaks in hospitals
75
are non-haemolytci streptococci part of normal bowel flora or nah
yes
76
two types of staphylococci
- S. Aureus
| - S. Epidermis
77
describe staphylococcis differentiating features
gm+ve irregular clusters, non-motic, +ve catalse, -ve oxidase, coagulase can be either, aerobe and faculative anaerobe, 15% NaCl
78
where does S. aureus usually stay
| where does it break out
- anterior nares and perineum
| - nosocomial and community
79
where does S. epidermis usually stay
| where does it break out
- skin and mucosal membranes
| - nosocomial and immunocompromised
80
where and who does MRSA infect
- nosomical in ICU - IV lines
| - immunocompromised, elderly, burns, dialysis and surgical patients
81
what are S. epidermis infections associated with
foreign bodies
82
what is the most common skin, soft tissue, wound, bone and joint infection
S. Aureus
83
what type of S. aureus causes food poisoning
enterotoxin producing strains
84
how does S. aureus cause
- local inflam
- bacteremia
- sepsis
- multiplies at sites of acquisition
- once its in bloodstream
- disseminates to distant sites in the body
85
where does S. aureus cause abscesses
spleen, liver, kidney
86
describe clostriodes differentaiting features
- gm +ve, anaerobic bacilli
- normal flora
- spore producing
87
clostriodes produce spores meaning what
they can survive outsidethe body for months
88
what type of clostriodes produce enterotoxins
- C. difficile
- C. perfringens
- C. tetani
89
what infection is C. difficile associated with
antibiotic associated diarrhoea in the elderly
90
what infection is C. perfringens associated with
gangrene
91
what infection is C. tetani associated with
tetanus
92
what can enterotoxin producing clostriodes cause
severe tissue damage
93
what causes pseudomembranous colitis
C. difficule
94
what is the link of C. difficile to antibiotic therapy
proliferates in absence of normal bowel flora
