Dr.Namrata

Vibrios requiring a higher concentration of sodium chloride

natural inhabitants of sea water and marine life

V. parahaemolyticus, Vibrio alginolyticus,V. vulnificus - important halophilic vibriosspecies known to cause infection in humans

important cause of seafood-associated gas

troenteritis throughout the world

differs from V. cholerae by having a capsule showing bipolar staining and pleomorphism

it has polar flagella when grown in liquid culture, but shows peritrichous flagella whengrown on solid media.

salt concentration : up to 8%

Growth characters:

Mac:nonlactose- fermenting colonies

Blood agar:beta-hemolytic colonies

TCBS:nonsucrose-fermenting green colonies

oxidase – positive

Catalase - positive

Antigens:

somatic O antigens,

flagellar H antigens,

capsular K antigen.

Serotyping is based on O and K antigen.

Virulence factors:

Thermostable direct hemolysin is the key virulence factor of V. parahaemolyticus.

This is found only in strains that are pathogenic to human beings.

Kanagawa phenomenon

Pathogenic strains of V. parahaemolyticuswhen grown on a special high-salt mannitol medium (Wagatsuma agar) show hemolysison blood agar

Nonpathogenic strains isolated from environment that do not cause any hemolysis

Habitat:

is widely distributed in estuary and marine environments.

Seafood, such as fish, crabs, or oysters, is the main source and reservoir of infection.

The infection is acquired on consumption of contaminated seafood.

Clinical manifestations:

in humans causes gastroenteritis

severity of the condition can vary from mild self-limited diarrhea to an acute illness

nausea,vomiting, abdominal pain, and low-grade fever, which may be present for 3 days

Stool usually does not contain any blood or mucus, but contains cellular exudates

Extraintestinal infections:

wound infections and ear and eye infections

in individuals exposed to contaminated sea water

V. alginolyticus is widely distributed in sea water and seafood.

high salt tolerance and can grow even in the presence of 10% sodium chloride

TCBS agar: large yellow sucrose-fermenting colonies.

shows swarming on the surface of nonselective medium, such as blood agar

associated with infections of superficial wounds exposed to contaminated sea water

has been associated with infections of the

gastrointestinal tract, ear, and eye.

Properties Vibrioparahaemolyticus

Vibrioalginolyticus

Growth in 10% agar - +

Presence of swarming

- +

Fermentation of sucrose

- +

VP test - +

formerly known as L vibrio,or Benekeavulnificus

TCBS: produces green nonsucrose-fermenting

colonies on TCBS medium

differs from V. parahaemolyticus and other Vibrio species by its ability to ferment lactose

Virulence:

more virulent bacterium than V.parahaemolyticus.

capsule

hydrolytic enzymes, such as cytolysins, proteases, and collagenases

resistant to complement- and antibody-mediated lysis

Clinical manifestations:

wound infection and

gastroenteritis rapidly progressing to septicemia

Wound infections:

caused by contaminated sea water

short incubation period of 3–24 hours

wounds are usually present on the fingers, palms, or soles of the feet

rapidly progresses to necrosis, gangrene,ornecrotizing fasciitis

Gastroenteritis:

following the consumption of raw seafood on exposure

rapidly progresses to septicaemia

manifests as multiple hemorrhagic bullae and extensive ecchymosis distributed on the lower extremities

Hypotension , oliguria and noncardiogenicpulmonary edema

V. vulnificus produces life-threatening illness,

immediate and prompt treatment with antibiotics is essential.

Tetracyclines or aminoglycosides are the antibiotics of choice

The condition is prevented by avoidance of raw and undercooked seafood.

PSEUDOMONAS

A large group of aerobic, non sporing

gram negative bacteria motile by polar

flagella

Found in water, soil, other moist

environments

Some of them are pathogenic to plants

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Classification

◦ Based on rRNA – DNA homology groups

Five ribosomal RNA groups

◦ Based on Phenotypic characters

Seven groups – Fluroscent, stutzeri, alcaligens,

pseudomallei, acidovorans, facilis & diminuta

Gram negative bacteria

Size 1.5 – 3 x 0.5 µ m

Actively motile by polar flagella

Produces extracellular polysaccharide k/a

alginate

Obligate aerobe

Grows at a temp range of 6 - 420 C

Produces colonies with distinctive musty, mawkish or earthy smell.

Growth on Blood agar -

colonies are moist flat, irregular edges,

greenish pigmented, showing zone of

hemolysis

Growth on MacConkey agar –

Non lactose fermenting colonies

Growth on Nutrient agar –

Greenish pigment

Pyocin

Pyorubin

Pyomelanin

Fluroscein

Selective media

Cetrimide agar

Pigment enhancing media

King’s A

King’s B

Cell surface

◦ Alginate

◦ Lipopolysaccharide

◦ Pili

◦ Flagella

Outer membrane

◦ Siderophore receptors

◦ Efflux pumps

Type III secretions

Secreted proteins

◦ Las A

◦ Las B

Iron acquisition

◦ Pyoverdine

◦ Pyochelin

Secreted toxins

◦ Exotoxin A

◦ Leucocidin

◦ Phospholipidases

Quorum sensing

Complex and diverse

Rarely causes infection in healthy individuals

Disruption of cutaneous / mucosal barrier

◦ Burns

◦ Dermatitis

◦ Penetrating trauma

◦ Surgery

◦ Endotracheal intubation

◦ Catheterisation

Immunosuppression

◦ Neutropenia

◦ Hypogamaglobulinemia

◦ Defective CMI

◦ Extremes of age

◦ Diabetes mellitus

◦ Steroids

◦ Cystic fibrosis

◦ AIDS

◦ cancer

Disturbed normal flora

◦ Long term hospital stay

◦ Broad spectrum antibiotics

Host factorsBacterial factors

Attachment

Invasion

Epithilium

Soluble factors

Anaphylotoxins

Neutrophils

Complement

factors

Pili

Flagella

Alginate

LPS

OMP

Type III secretion

LPS

Elastase

Proteases

SiderophoresToxins

Can cause infection anywhere

In adults mostly associated as a nosocomial

pathogen

In paediatric population it mainly causes

infection in cystic fibrosis patients

Superficial infections◦ Burn wound infections

◦ Otitis externa / Malignant otitis externa

◦ Pseudomonas keratitis

Systemic infections

◦ Respiratory tract infections

◦ Bacterimia

◦ Endocarditis

◦ CNS infections

◦ Urinary tract infections

◦ Bone and joint infections

Hospital acquired infections

Pneumonia

◦ Endotracheal tubes

◦ Ventilator tubings

◦ Humidifiers

◦ Nebulizers

Catheter associated infections

◦ UTI

◦ Line associated bacterimias

Iatarogenic meningitis

◦ Post lumbar puncture

◦ Post neurosurgery

Sample collection

◦ Respiratory tract infection

Sputum

Bronchioalveolar lavage

Bronchial washings

◦ CNS infections

CSF

◦ Bacteremia

Blood

◦ Eye infections

Corneal scrapings

Contact lenses

Lens fluid

◦ Ear infection

Ear swabs

◦ Superficial infections

Wound swabs

Microscopy Gram’s staining

Culture

◦ BA

◦ MA

◦ Selective medium

Biochemical reactions

◦ Oxidase

◦ Hugh & Leifson’s OF reactions

Antibiotic sensitivity

Pyocin typing

Molecular methods

Aminoglycosides

Gentamycin, Amikacin, Cephalosporins

Cefotaxime. Ceftazidime. Ofloxacin,

Piperacillin, ticarcillin

Local application, colistin, polymyxin

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Septicaemia Endocarditis Ecthyma

gangrenous Infantile diarrhoea Shanghai fever Disabling eye

infections Survive with

minimal nutrients

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Patients with cystic fibrosis are highly susceptible to pseudomonas lung infections.

cancer

burn patients

immunocompromised..

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Pseudomonas aeruginosa is the most frequently encountered lung pathogen in patients with cystic fibrosis (CF). Following initial, often intermittent, episodes of infection, it becomes a permanently established component of the chronically infected lung in more than 80% of patients

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Respirators Endotracheal tubes

Can be Infected

All equipment's to be sterilized

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Toxic extracellular products in culture filtrates

Exotoxin A and S

Exotoxin A acts as NADase resembling Diphtheria toxin

Proteases,elastatese hemolysins and enterotoxin

Slime layer and Biofilms

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Diagnosis of P,aeroginosa infection depends upon isolation and laboratory identification of the bacterium.

blood agar / eosin-methylthionine blue agar

Grams

inability to ferment lactose,

a positive oxidase reaction, its fruity odour, and its ability to grow at 42°C. Fluorescence under ultraviolet light is helpful in early identification of P.s aeruginosa colonies. Fluorescence is also used to suggest the presence of P. aeruginosa in wounds.

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P. aeruginosa

Prevention and Control

Pseudomonas spp. normally inhabit soil, water, and vegetation

and can be isolated from the skin, throat, and stool of healthy

persons.

Spread is mainly via contaminated sterile equipment's and

cross-contamination of patients by medical personnel.

High risk population: patients receiving broad-spectrum

antibiotics, with leukemia, burns, cystic fibrosis, and

immunosuppression.

Methods for control of infection are similar to those for other

nosocomial pathogens. Special attention should be paid to sinks,

water baths, showers, hot tubs, and other wet areas.

Thank you