Vibrio and Other Gram-negative bacilli

Klebsiella pneumoniae

• Friedlander’s bacillus

• Most common isolate

• Non-motile

• Gram-negative (-) coccobacilli or diplobacilli

Anti-phagocytosis, Anti-complementary

Virulence mechanism of capsule

• Fever & chills

• Hypotension

• Hemorrhage and ischemic changes of the organs

Endotoxins of K. pneumoniae induces:

skin, throat, and GIT

K. pneumoniae is normal inhabitants of?

Klebsiella rhinoscleromatis

Rhinoscleroma

Klebsiella oxytoca

• Nosocomial: neonatal bacteremia

• Petechia and purpura: sign of bacteremia

Klebsiella ozaenae

Primary atrophic rhinitis

• MacConkey agar

• Eosin Methylene Blue agar

Culture media of choice for Klebsiella species:

Acid slant / acid butt, with gas, without H2S

Klebsiella pneumoniae triple sugar iron result

Acid slant / acid butt with gas without H2S

Klebsiella oxytoca triple sugar iron result

fish-eye colonies

Enterobacter forms what colonies on EMBA?

Red colonies

Enterobacter forms what colonies on MacConkey agar?

water, soil & normal flora of the intestine

Enterobacter’s habitat is?

acid slant/acid butt, without gas, without H2S

Triple sugar iron result of Enterobacter

Serratia marcescens

• Most common Serratia

• Opportunistic pathogen

• Known for their resistance to a wide range of antimicrobials

• Causative agent of LECK

HAI: UTI & RT

• Found frequently in hospital acquired infections (HAI) of the urinary tract or respiratory tract

• And in bacterial outbreaks in nurseries and cardiac surgery and burn units

SEPTIC ARTHRITIS

Contamination of antiseptic solution used for joint injections

True

True or False: Serratia marcescens ocular infections have been associated with contact lens wear (especially rigid gas permeable contact lenses) and previous eye surgery

Citrobacter freundii

• Facultative anaerobes

• Lactose fermenter

• The ONLY Lactose fermenter to produce hydrogen sulfide

• motile

• hydrolyzes urea slowly

• Ferment glucose & lactose with acid and gas production

rose pink colonies

Colonies of Citrobacter freundii in MacConkey agar

acid slant/acid butt, without gas, with H2S

Triple sugar iron result of Citrobacter freundii

Proteus group

• Gram-negative (-)

• Pleomorphic bacilli

• Highly motile: peritrichous flagella

Urease test and Phenylalanine deaminase test

Test used to identify proteus group

Proteus vulgaris and Proteus mirabilis

Swarming colonies

Morganella morganii, Providencia rettgeri

Non-swarming colonies

O1 and 139

2 epidemic serotypes of Vibrio

• Classical

• El tor

O1 is divided into 2 biotypes based of biochemical reactions; what are the 2 biotypes

• Ogawa

• Inaba

• Hikojima

3 ribotypes of O1

Ogawa

containing A & B antigens

Inaba

containing A & C antigens

Hikojima

containing A, B, & C antigens

Classical

Sensitive to Polymyxin B

El tor

resistant to Polymyxin B

Vibrio

• Gram-negative (-)

• Oxidase positive (+)

• Comma-shaped

• Motile (single thick polar flagellum à monotrichous)

Endotoxin

Caused baby gram-negative bacteria

Enterotoxin (Choleragen)

Responsible for diarrhea in vibrio

Flagella

Acts as an adhesive & binds the bacteria to cellular surfaces

Mucinase

Enzyme that destroys mucin in intestinal tract; Enables organism to adhere to the cells of the brush border of the gut or intestinal tract by dissolving the protective glycoprotein coating the intestinal cells

10M bacilli (106 – 1011 CFU)

Infecting dose of Vibrio cholerae

Houseflies and other insects

carriers of Vibrio cholerae

Bacterium transmitted through contaminated 4F’s (humans to humans) and via contaminated water and food

MOT of Vibrio cholerae

rice water stool

description of stool caused by cholera

2-3 days; may be hours or a few days with a mean of 2-3 days

Incubation period of cholera

Choleraic facies

• Washerwoman’s hand appearance

• Sunken eyeballs

• Due to severe dehydration

• Tellurite Taurocholate Gelatin Agar (TTGA)

• Thiosulfate Citrate Bile Salt Sucrose Agar (TCBS)

Culture media used for Vibrio cholerae

Flattened, transparent colonies surrounded by a cloudy halo

Colonies of Vibrio cholerae in TTGA

Thiosulfate Citrate Bile Salt Sucrose Agar (TCBS)

Culture medium of choice for Vibrio cholerae

Flat yellow colonies with opaque center and transparent periphery

Colonies produced by Vibrio cholerae in TCBS

rapid darting or shooting motility

in darkfield microscopy, cholera bacilli exhibit a?

acid slant / acid butt, no gas

Triple sugar iron result of Vibrio cholerae

• Motile

• halophilic vibrio naturally found in the marine environment and seafood

• Commonly associated with seafood

• It can be destroyed by heating at 75C or above for several minutes.

• needs 2% NaCl for optimum growth

Vibrio parahaemolyticus

4-30 hours, usually 12-24 hours

incubation period of Vibrio parahaemolyticus

explosive & watery with no blood & mucus

diarrhea of Vibrio parahaemolyticus

Consumption of raw/undercooked seafood or cooked food that has been cross contaminated with bacteria without further cooking

MOT of Vibrio parahaemolyticus

Isolation media containing 2%-4% NaCl

Isolation media for Vibrio parahaemolyticus

large, green smooth colonies

Colonies produced by Vibrio cholerae in TCBSA

Vibrio vulnificus

• Mostly causes outer ear infection (swimming) & wound infection

• Associated with raw oysters

• Common in warm brackish water, low salt

• Can also cause bacteremia & liver disease

Campylobacter

• Among the most widespread cause infection in the world

• Cause both diarrheal and systemic disease

• Oxidase positive (+)

• Identified by its failure to grow at 25°C

• Sensitive to nalidixic acid

• Microaerophilic

Campylobacter jejuni

• diarrhea

• Grows well at 42C

• Major cause of diarrhea in the U.S.A.

Campylobacter intestinalis

• bacteremia

• Does not grow well at 42C

104 organisms

Infecting dose of Campylobacter

4-8 days

incubation period of Campylobacter

Enterocolitis

• Commonly due to Campylobacter jejuni

• Incubation period: 1-7 days

• Begins as watery, foul-smelling diarrhea followed by bloody stools accompanied by fever abdominal pain after an incubation period of 1-7 days

• Production of diarrhea is similar to that of Cholera

Systematic infections

• Due to Campylobacter intestinalis

• Bacteremia

flat, droplet-like, glistening colonies

colonies of Campylobacter jejuni

Helicobacter pylori

• Curved bacilli; lophotrichous flagella

• Is the prototype organism in this group

• It is associated with antra gastritis, gastric ulcers, and gastric carcinoma

• Very motile → corkscrew motion

• use amino acids and fatty acids rather than carbohydrates to obtain energy

• needs 10% CO2 and 5% O2

• Urease positive (+) like Proteus à urease breath test

• Catalase positive (+) Produce catalase

• Oxidase positive

• Grow at 37C, not 25C or 42C

human gastric mucosa

primary habitat of Helicobacter pylori

Gastritis & duodenal ulcer

are characterized by recurrent pain in the upper abdomen, frequently accompanied by bleeding in the gastrointestinal tract

C. jejuni

• Catalase (+)

• Nitrate reduction (+)

• Hippurate hydrolysis (+)

• Growth on 42C

• Sensitive to Nalidixic acid

• Resistant to Cephalothin

C. intestinalis

• Catalase (+)

• Nitrate reduction (+)

• Hippurate hydrolysis (+)

• Resistant to Nalidixic acid

• Sensitive to Cephalothin

H. pylori

• Catalase (+)

• Urease (+)

• Resistant to Nalidixic acid

• Sensitive to Cephalothin