Download 3_Gram Negative Bacteria of Medical Importance

ZaidKhalid MBBS220
Gram Negative Bacteria of Medical Importance
Gram Negative Bacteria
Curved
rods
Coccus
Aerobic
Niesseria
Moraxella
Anaerobic
Rods
Vibrio
Campylobacter
Helicobacter
Veillonella
Aerobic
Anaerobic
Fastidious
Oxidase
Test
Bacteriodes
Haemophilus
Porphyromonas
Bordetella
Prevotella
Brucella
Legionella
Positive
Negative
Pseudomonas
Enterobacteriacae
Stenotrophomonas
Burkholderia
Lactose Fermenter
Non-lactose
fermenter
Klebsiella
Samonella
Escherichia
Shigella
Eneterobacter
ZaidKhalid MBBS220
COCCUS
Name of
Lab Characteristics
bacteria
Neisseria
1. Non-motile
1. Gonorrhoea 2. Diplococci
2. Meningitidis 3. Fastidious
a. Capnophilic
4. Grow on
a. Chocolate agar
b. Thayer-Martin agar
5. Neisseria gonorrhoeae
a. Enriched media with
VCNT
i. Vancomycin
ii. Colistin
iii. Nystatin
iv. Trimethoprim
6. Oxidase positive
7. Encapsulated
a. Meningitidis-yes
b. Gonorrhoeae-no
8. Way to differentiate them
a. Meningitidis –
glucose+maltose
b. Gonorrhoeae-glucose
Virulence factors
1. Gonorrhoeae
a. Pili for adhesins
b. Endotoxin
c. Outer membrane
protein
d. Protease
production
e. Resistance to
i. Phagocytosis
ii. IgA protease
2. Meningitidis
a. Polysaccharide
capsule
b. Endotoxin
c. IgA protease
resistant
Transmission
Clinical diseases
Treatment
1. Only available in
human being
2. Gonorrhoeae
a. Genital tract
b. Nasopharynx
c. Anus
d. Spreads thru
sexual
intercourse
3. Meningitidis
a. Pharynx
b. Spreads thru
droplets of
water
Gonorrhoeae
1. Gonorrhoea
2. Pelvic
inflammatory
disease
3. Salphingitis
4. In infant(gets from
infected mom)
a. Ophthalmia
nonatorum
Meningitidis
1. Meningitis
2. Septicaemia
Gonorrhoeae
1. NonPPNG=Penicillin
2. PPNG=
a. Ceftriaxone
b. Spectinomycin
c. Ciprofloxacin
3. No vaccine
Meningitidis
1. Rifampicin for
prophylaxis
2. Tetravalent
vaccine available
ZaidKhalid MBBS220
CURVED RODS
Name of
bacteria
Vibrio
Types of vibrio
1. Cholerae
2. Parahaemol
yticus
Lab Characteristics
1. Highly motile; single
flagellum
2. Grow in alkaline
condition
a. Alkaline peptone
water
3. TCBS forms
a. Yellow (cholera)
b. Green
(parahaemolyticus)
4. Oxidase positive
Name of
bacteria
Campylobacter
jejuni
Lab Characteristics
1.
2.
3.
4.
Slender curved
Microaerophilic
Motile, polar flagellum
Skirrow’s medium with
antibiotic
a. Incubation for 24-72
hrs at 42oC
i. 5% O2
ii. 10%CO2
5. Colonies= water drops
Virulence factors
Transmission
Clinical diseases
Treatment
Cholerae
1. Cholerae
1. Mucinase
a. Contaminated
2. Adhesins
food and water
3. Enterotoxins
2. Parahaemolyticus
a. Chromosomally
a. Contaminated
mediated
seafood and fish
b. Binds to
ganglioside
receptors
c. Activate adenyl
cyclase
d. Causing fluid loss
e. Massive watery
diarrhoea
Parahaemolyticus
1. Cytotoxin
Virulence factors
Transmission
1. Cholerae
a. Cholera
2. Parahaemolyticus
a. Food poisoning
1. Fluid replacement
therapy
2. Tetracycline to
shorten the
infection
3. Oral vaccine
available
4. Prevention of
cholera is based
from good sanitary
management
5. No specific Tx for
parahaemolyticus
diarrhoea
Clinical diseases
Treatment
1. Cytotoxin
2. Infection and
destruction of gut
mucosa
1. Gastroenteritis
2. Bacteremia
1. Animal reservoir
2. Contaminated food
and milk
3. Person to person
spread is very rare
1. No specific Tx for
diarrhoea
2. Erythromycin for
bacteremia
3. Good food hygiene
ZaidKhalid MBBS220
Name of
bacteria
Helicobacter
pylori
Lab Characteristics
1. Spiral shape
2. Motile, multiple
flagellum
3. Skirrow’s medium with
antibiotic
a. Incubation for 24-72
hrs at 42oC
i. 5% O2
4. Microaerophilic
5. Differentiated from
campylobacter by
a. Nitrate reduction
i. Campyl-positive
ii. Helico-negative
b. Urease
i. Helico-positive
ii. Campyl-negative
Virulence factors
1. Produces
a. Protease
i. Modifies gastric
mucus
ii. Reduce ability of
acid to diffuse
thru mucus
b. Potent urease
i. Yields ammonia
ii. Buffering more
acid
Transmission
1. Person to person
transmission
2. Faecal-oral
transmission
3. Infections observed
in multiple family
members
Clinical diseases
1.
2.
3.
4.
Antral gastritis
Peptic ulcer
Gastric ulcer
Gastric carcinoma
Treatment
1. PPI plus antibiotics
a. Clarithromycin
b. Metronidazole
c. Tetracycline
2. PPI is a potent urease
inhibitor
3. Triple treatment with
a. Metronidazole+
Bismuth
subsalicylate/
bismuth salicylate
+ amoxy/tetra
ZaidKhalid MBBS220
RODS
Aerobic/Oxidase test positive
Name of
bacteria
Pseudomonas
aeruginosa
Lab Characteristics
1. Motile; polar flagella
2. Does not ferment carb
3. Grows readily in routine
media, characteristic smell
4. Pigmentation
a. Pyocynin
i. Blue
b. Pyoverdin
i. Yellow
c. Pyorubin
i. Red
d. Pyomelanin
i. Black
5. Oxidase positive
Virulence factors
Transmission
1. Endotoxin
2. Exotoxin A
3. Extracellular
polysaccharide
prevent phagocytosis
4. Pigment
a. Pyoverdin as
siderophore
1. Found in hospital
settings
2. Widespread easily in
a moist area such as
hospital
3. Infected thru directly
or indirectly to the
environment
Clinical diseases
1. Opportunistic
pathogens
2. Skin infection and
burns
3. Cystic fibrosis
4. Pneumonia in
ventilated patient
5. UTI
6. Septicaemia
Treatment
1. Resistant to many
antibiotic
2. Resistance develops
rapidly during Tx
3. Combination
antibiotic based on
susceptibility test
a. Aminoglycosides
b. B lactam
antibiotics
4. Prevention
a. Good hospital
aseptic technique
b. Avoid unnecessary
and prolonged use
of antibiotic
ZaidKhalid MBBS220
RODS
Aerobic/Oxidase test Negative
Lactose fermenter
Name of bacteria
Escherichia coli
Lab Characteristics
1.
2.
3.
4.
5.
6.
Motile
Sometimes encapsulated
Facultative anaerobe
Bile tolerant
Grows well in blood agar
Ferments lactose
a. Pink- McConkey agar
b. Yellow-CLED
7. Commercial kit-API 20E
Virulence factors
1. Powerful toxin
2. Enterotoxin (coded on
plasmids)
a. Heat sensitive
b. Heat labile
3. Colonization factor
antigen
4. Plasmid coded pili
5. Verotoxin that can cause
haemorrhagic diarrhoea
Name of bacteria
Klebssiella sp.
Enterobacter sp.
Serratia sp.
Transmission
1. Endogenous
2. Exogenous
Clinical diseases
1. Types of E.coli can cause diarrhoea
a. Enteropathogenic (EPEC)
b. Enteroinvasive (EIEC)
c. Enterotoxigenic (ETEC)
d. Enterohaemorrhagic (EHEC)
e. Enteroaggregrative (EAEC)
2. UTI
Explanation
1. Found in human
a. Intestine
b. Respiratory tract
2. Nasocomial infection in immunocompromised pts on
a. Ventilator
b. IV catheter
3. Serratia marcescens
a. Produces magenta colony
b. Fatal to
i. Neonates
ii. Immunocompromised pts
iii. Debilitated pts
ZaidKhalid MBBS220
RODS
Aerobic/Oxidase test Negative
Non-Lactose fermenter
Name of
bacteria
1. Salmonella
a. Typhi
b. Parathypi
Name of
bacteria
Shigella
1. Dysnteriae
2. Sonnei
3. Flexneri
4. Boydii
Lab Characteristics
1. Motile
2. Non-forming spore
3. Salmonella typhi is
NONCAPSULATED
4. Facultative anaerobes
5. Non-lactose
fermenter
Lab Characteristics
1. No – motile
2. Noncapsulated
3. Non lactose
fermenter ; sonnei
slow lactose
fermenter
4. Commercial kits of
API20e
Virulence factors
1. Antigen O –somatic
2. Antigen H – flagellum
3. Antigen Vi – virulence,
notably found in typhi
Virulence factors
1. Invade ileum and colon
2. Intense inflammatory
response, bloody
diarrhoea
3. Exotoxin is neurotoxin
Clinical diseases
1. Enteric fever
a. Typhoid fever
b. Paratyphoid fever
2. Gastroenteritis
a. Due to salmonella enteritidis
b. Due to the consumption of highly
contaminated
i. Food
ii. Beverage
3. Septicaemia
a. Fatal disease
b. Pneumonia, meningitis and osteomyelitis are
secondary
Transmission
Clinical diseases
1. Live only in
1. Dysentery
human intestines
2. Feacal-oral in
crowded area
3. Minute dose of
organisms can
cause disease
Treatment
1. Proper cooking
a. Food form animal
resources
2. Typhoid fever vaccine
a. Killed salmonella
typhi suspension
b. Oral attenuated
salmonella typhi
TY21a
Treatment
1. Fluid and electrolyte
replacement Tx
2. Antibiotics should be
avoided; multiple
resistant found
3. Personal hygiene and
proper sanitation
ZaidKhalid MBBS220
RODS
Anaerobic
Name of
bacteria
Bacteriodes
fragilis
Lab Characteristics
1. Pleomorphic
coccobacilli
2. Blood agar, incubated
anaerobically
a. Kept for 48hrs at
37oC for them to
be visible
3. Have foul odour, fatty
acid
Virulence factors
1. Polysaccharide capsule
2. Extracellular enzyme
Transmission
1. Contamination
of gut contents
/faeces
Clinical diseases
1.
2.
3.
4.
5.
Intra-abdominal sepsis
Liver abscesses
Aspiration pneumonia
Brain abscesses
Wound infection
Treatment
1. Metronidazole
2. B lactam antibiotic
resistant
3. Surgical technique
can be employed
ZaidKhalid MBBS220
RODS
Fastidious
Name of
bacteria
Haemophilus sp
1. Influenzae
2. Ducreyi
Live in human
upper respiratory
tract
Name of
bacteria
Bordetella
pertussis
Lab Characteristics
Virulence factors
1. Identification
1. Polysaccharide
a. Influenzae
capsule
i. Factor X (+)
2. Endotoxin
ii. Factor V (+)
3. Outer
b. Ducreyi
membrane
i. Factor X (+)
protein
ii. Factor V (-)
2. Coccobacilli
3. Capnophilic
4. Encapsulated
5. Grows on chocolate agar
6. Larger colonies with S. Aureus
7. Type b antigen is pathogenic
Lab Characteristics
1. Slow growing
2. Fastidious
3. Grows on enriched media
a. Bordet-Gengou media
b. Blood charcoal agar
4. Identify by specific antisera
Virulence factors
1. Tracheal
cytotoxin
2. Fimbrial
antigen
3. Lymphocytic
promoting
factor
Transmission
1. Person to person;
airborne
Transmission
1. Airborne spread
2. No healthy carrier
documented
Clinical diseases
1. Influenzae
a. Meningitis
b. Osteomyelitis
c. Acute apiglotitis
d. Otitis media
2. Ducreyi
a. Chancroid/genital
tract infection
Clinical diseases
1. Whooping cough
(pertussis)
Treatment
1. Amoxicillin
2. 3rd generation
cephalosporin
a. Ceftriaxone
3. Children are
immunized by
a. H.inlfuenzae
serotype b
polysaccharide
vaccine
4. Rifampicin for
prophylaxis in
H.influenzae
meningitis
Treatment
1. Erythromycin
2. May reduce
infectivity and
incidence of
superinfection
3. Vaccine together with
tetanus and
diphtheria
4. Newer subunit
vaccines are also
effective
ZaidKhalid MBBS220
Name of bacteria
Lab Characteristics
Virulence factors
Transmission
Clinical diseases
Treatment
Brucella
1. Abortus-cattle
2. Suis-pig
3. Canis-dog
4. Melitensis-goat
Causing the zoonotic
infection
1. Coccobacilli
2. Require complex nutrition
for growth
3. Castaneda bottles
containing both broth and
blood
4. Requires 3-5days of
incubation in CO2
enriched media, some up
to 4 weeks
1. Can survive
intracellular in
a. Bone
marrow
b. Liver
c. Spleen
1. Zoonotic infection
a. Consumption
of
contaminated
milk/unpasteur
ised dairy
product
b. Direct contact;
occupational
hazard
1. Undulant fever
a. Can be chronic if not
treated adequately
1. Doxycyline alone
2. Doxycycline plus
a. Streptomycin
b. Rifampicin
3. Vaccination of live
stocks and
pasteurisation of milk
Name of bacteria
Lab Characteristics
Clinical diseases
Treatment
Legionella
pneumophilla
1. Pleomorphic
2. Coccobacilli
3. Need enriched media with
iron and cysteine, and
charcoal to remove fatty
acid (BCYE)
4. Incubate for 3-5 days;
produce small tenacious
colonies
Virulence factors
1. Intracellular survival in alveolar
macrophage
2. Predisposing factors
a. Smoker
b. Chronic lung disease
c. Immunocompromised
1.
2.
3.
4.
Legionnaire disease
Atypical pneumonia
Pontiac disease
Diagnosis based on
antibody detection
1. Erythromycin plus
a. Ciprofloxacin
b. Rifampicin
2. No vaccine available
3. Prevention thru
proper maintenance
of
a. Hot water
b. Air cond