Micro lecture 23 - Pseudomas aeruginosa, Burkholderia spp., Klebsiella pneumoniae, Proteus mirabilis and P. vulgaris

Pseudomas aeruginosa

-opportunistic infection, affecting compromised tissue

-Pulmonary infections

-open wound and soft tissue infections

-epidemiology: Ubiquitous (commonly found in water and soil), 10% of nosocomial infections (Healthcare-associated infections!)

P. aeruginosa Virulence Factors

-Attachment factors: pili
-Capsule: anti-phagocytic
-Biofilm formation: protection
-Algninate synthesis (viscous gel around bacterium)
-LPS
-Pyocyanins generates ROS contributing to tissue destruction
-Siderophores capture iron and other nutrients
-Multiple secretory systems

Exotoxin A - P. aeruginosa

blocks protein synthesis by ADP-ribosylating elongation factor 2 (EF-2) like diphtheria toxin

Phospholipase C - P. aeruginosa

degrades host cell membrane

Exoenzymes S and T and elastases LasA and LasB - P. aeruginosa

prevents phagocytic killing

Pseudomonas aeruginosa - biochemistry

-Gram-negative rod, polar flagella
-Strict aerobe, simple growth requirements, β hemolytic
-Distinct color and odor when grown the solid medium (grape-like); pyocyanin: blue-green pigment
-Oxidase positive

Burkholderia spp.

-Gram-negative bacillus

-pathogens: B. mallei, B. pseudomallei., B. gladioli

-Epidemiology: moist environments and surfaces, Biodefense potential, so classified as a select agent

Burkholderia spp. virulence factors

-LPS
-Polysaccharide capsule
-Produce unique "cable pili"
-Biofilm production

Do Pseudomonas and Burkholderia ferment lactose?

No

Burkholderia Diseases

Opportunistic pathogens often associated with specific underlying diseases or conditions

-Diseases: primarily respiratory, esp. in cystic fibrosis

Melioidosis

-caused by Burkholderia pseudomallei

-Transmission: percutaneous inoculation and inhalation

-Pneumonia is the most common clinical presentation

Klebsiella pneumoniae

-Gram-negative rod, an Enterobacteriaceae

-Biochemical identification: Grows pink colonies on MacConkey’s agar

Klebsiella pneumoniae virulence factors

-Prominent anti-phagocytic capsule that gives colonies a mucoid appearance
-Forms biofilms
-Attachment: fimbriae
-Increasing drug resistance: KPC, ESBL, NDM-1
-Siderophores
-LPS

K. pneumoniae Disease

-Epidemiology: Part of intestinal flora

-Transmission: Can be found in healthcare settings → frequent nosocomial pathogen

-Disease: Usually necrotic destruction of alveolar spaces, formation of cavities, and production of blood-tinged sputum (in contrast to rust-colored sputum of S. pneumoniae – different virulence mechanisms).

Klebsiella granulomatis

-Gram-negative rod in Enterobacteriaceae family

-Very pronounced capsule: gives mucoid appearance and is a major virulence factor

-Causes granuloma inguinale or donovanosis

-Clinical presentation: Subcutaneous nodules then appear on genitalia or inguinal area; granulomatous lesions that are painless

Proteus mirabilis and P. vulgaris

-contains peritrichous flagella -> highly motile

-Swarming growth (motility) on blood agar

-H2S and urease positive

-Colonize colon and (in women) urethra

Diseases from Proteus mirabilis and P. vulgaris

-P. mirabilis: urinary tract infection

-P. vulgaris: nosocomial infections (pneumonia, bacteremia) and UTIs

Pseudomas aeruginosa presentation

-pulmonary infections

-soft tissue infections

-makes up 10% of nosocomial infections

-blue green pigments

what are pyocyanins?

virulence factors of P. aeruginosa that generate ROS, contributing to tissue destruction

biochemistry of pseudomonas aeruginosa

-gram negative, polar flagella
-strict aerobe, simple growth requirements
-grape odor
-oxidase positive

Burkholderia spp.

-gram negative bacillus
-B. pseudomallei
-soil organism
-biodefense potential, respiratory illnesses

burkholderia diseases

opportunistic infection associated with cystic fibrosis

meliodosis

Burkholderia
-presents like pneumonia
-percutaneous inoculation and inhalation

klebsiella pneumo on agar

-pink colonies on MacConkey's agar
-gram negative rod

biochemical properties of Klebsiella

-lactose fermenter
-oxidase negative
-urease positive
-large capsule

K. pneumoniae

-marked by blood tinged sputum
-nosocomial

Klebsiella granulomatis presentation

-extended incubation

-nodules then appear on genitalia or inguinal area

-lesions are painless

Proteus mirabilis/vulgaris

-highly motile

-swarming growth

-H2S and urease positive

-associated with UTIs

unique feature of enterobacter

becoming increasingly resistant to drugs
-cause of many nosocomial infections