Bacteriology- Gram negative bacilli Flashcards
Enterobacteraceae classification
Lactose fermenter- E.coli, Klebsiella, Citrobacter, Enterobacter
Late lactose fermenter- Shigella sonnei
Non lactose fermenter- Shigella, Salmonella, Proteus, Yersinia
Motility of enterobactericeae organisms
All except Shigella and Klebsiella are motile
IMViC test results of enterobactericeae organisms
Shigella and Yersinia show only methyl red test +
E. coli and Klebsiella are opp- E.coli ++–, Klebiella –++
Salmonella is -+-+
Urease test + is shown by
Klebsiella
Proteus
Urease positive organisms
‘PUNCHKSS’
Proteus
Ureaplasma
Nocardia
Cryptococcus
Helicobacter
Klebsiella
Staph epidermidis
Staph saprophyticus
If result is positive for IMV tests, the color is
Red
If result is positive for citrate, the color is
Blue
MacConkey agar is done for
Lactose fermentation
Pink color= lactose fermenter
Constituents of MacConkey agar
‘PLANT’
Peptone
Lactose– differential media
Agar
Neutral red- indicator media
Taurocholate (bile salts)- selective media
CLED medium
What is its indicator?
Cysteine Lactose Electrolyte Deficient
Indicator: Bromothymol blue
Allows growth of gram positive and negative organisms
To identify urinary pathogens
EMB agar
Eosin Methylene Blue
Blue or black colonies with metallic sheen around it
Media used to demostrate lactose fermentation
MacConkey agar
CLED (better)
EMB
Enteropathogenic E.coli
1. Seen in?
2. characteristics?
Causes pediatric/ infantile diarrhoea
Forms bundle forming pili/ plasmid coded
shows attachment effacement lesions
Enterotoxigenic E.coli
Caused traveller diarrhoea
Using colonization factor Ag
Enteroinvasive E.coli
Dysentery (similar to Shigella)
Uses virulence factor Ag
Sereny test +
Sereny test
mucopurulent keratoconjunctivitis on inoculation of bacteria into eye of guinea pig
Seen in EIEC, Shigella
Anton test is seen in
Listeria
Similar to sereny test
Kass criteria
> 10^5 CFU/ml is considered as UTI
Exceptions: ‘SPA’
Suprapubic aspiration
gram Positive organism +
Antibiotics/ diuretic intake
EHEC
Causes HUS (0157:H7)
Sorbitol MacConkey Agar (SMAC) -ve
Entero Aggregative E coli
Persistent diarrhoea
Stacked brick appearance
Strains of E coli
EIEC
ETEC
EAEC
EHEC
EPEC
DAEC (Diffuse adherent E coli)
K. pneumoniae
Lactose fermenter
Friedlander’s bacillus
Mucoid colony (bc capsulated)
String test positive
K. ozeanea causes
atrophic rhinitis
Mikulicz cells
Big foamy macrophages with pink bodies inside called Russell bodies
Donovan bodies
K. granulomatis (that causes donovanosis)
Which stains are used to do bipolar staining?
Wright Giemsa stain
Wayson stain
Donovan bodies show _____ appearance
Safety pin appearance
Other organisms that show safety pin appearance
V. parahemolyticus
Yersinia pestis
K. granulomatis
H. ducreyi
Burkholderia
Serratia can cause pseudohemoptysis d/t red pigment called
Prodigiosin
Proteus shows ____ growth
Swarming growth
Proteus
PPA (phenyl pyruvic acid test) positive
fishy odor
Diene’s phenomenon (if same strain, will merge)
Swarming growth is seen in
Proteus
V. parahemolyticus, alginolyticus
Serratia
B. cereus
C. tetani
Diene’s stain is used in
Mycoplasma
What are the different species of Shigella?
S. dysenteriae (most severe, produces Shiga toxin)
S. flexneri (common in India).
S. boydii (less common).
S. sonnei (mildest infection, MC in the world).
Transport media for Shigella
Sach’s Buffered glycerol saline
Enrichment media for Shigella and Salmonella
Selenite F broth
Tetrathionate broth
Selective media for Shigella and Salmonella
XLD-Xylose Lysine Deoxycholate
DCA- Deoxycholate agar
HE- Hektoen enteric agar
SS- Salmonella Shigella agar
Treatment for Shigella and Salmonella
Ciprofloxacin
Type of fever seen in Salmonella infection
Step ladder pattern fever
Features of Enteric fever
Longitudinal ulcers
Faget sign
Rose spots (2nd to 3rd week, fades on pressure)
Pea soup diarrhoea
Soft palpable spleen, liver
Faget’s sign
relative bradycardia
On Wilson Blair media, what is the appearance of colonies?
Jet black colonies
Testing done in each week for typhoid fever
Week 1- blood culture
week 2- Widal test, antibody test
week 3- stool culture
week 4- urine culture
Typhoid O antigen is?
Typhoid H antigen is?
Somatic Ag
Flagella Ag
Which antigen is different for all 3 typhoid species?
Flagella Ag
___ antigen of typhoid appears first and disappears first.
O antigen
New tests for Salmonella antigens
Typhidot
Dot blot
Best media for S. typhi
Wilson and Blair media
Species of Yersinia
Y. pestis
Y. enterocolitica
Y. pseudotuberculosis
Features of Y. enterocolitica and Y. pseudotuberculosis
They cause gastroenteritis
They have differential motility
They are urease positive
Optimum temperature for growth of Yersinia
-25 C
Incubate for 4 C for 1 week
Characteristic appearance of Yersinia colonies
Bull’s eye appearance on CIN agar
Types of Plague
Bubonic (2-7 days IP)
LN enlarged, painful; fever
Pneumonic (1-3 days IP)
Resp +, bioterrorism
Septicemic (2-7 days IP)
How is plague diagnosed?
Wayson stain/ Wright stain/ Giemsa stain: Bipolar staining (safety-pin appearance).
Culture: Blood, sputum, bubo aspirate on MacConkey or blood agar.
Serology & PCR for confirmation.
Ghee broth: Stalactile growth
What is the treatment for plague?
Streptomycin (first-line), Gentamicin, Doxycycline.
How is bubonic plague transmitted
Transmission: Flea bite (Xenopsylla cheopis).
