Learning outcomes The student should be able to list the medically important genera and species of negative non-fermentative gram-negative rods describe their microscobic appearance List their most important properties For Pseudomonas: -list the important biochemical properties -list the important virulance factors(toxins and enzymes) -list the main routes of transmission -list the important clinical manifestations and describe the pathogenesis -list the important properties used in laboratory diagnosis -list the most important antibiotic resistance properties

Non-fermentative Gram- negative bacilli

Enterobacteriacea √ Grow rapidly Have simple nutritional requirements Ferment glucose Oxidase negative Distinguish them from nonfermentative gram- negative rods

Pseudomonas and related organisms aerobic-nonfermenter-gram-negative bacilli  Pseudomonas aeruginosa  Burkholderia cepacia  Stenotrophomonas maltophilia  Acinetobacter baumannii  Acinotobacter lwoffii  Moraxella catarrhalis

Pseudomonas and related organisms opportunistic pathogens important cause of hospital infections resistance to antibiotics

Pseudomonas Ubiquitous  Soil, decaying organic matter, vegetation, water  Hospital environment Moist reservoirs, food, cut flowers, sinks, toilets, floor mops, respiratory therapy & dialysis equipment  EVEN “ disinfectant solutions ” Simple growth requirements (can even grow in distilled water!!!!!!!)

Pseudomonas Can transiently colonize  the respiratory and  gastrointestinal tracts of hospitalized patients, particularly those treated with broad-spectrum antibiotics,  exposed to respiratory therapy equipment, or hospitalized for extended periods can cause hospital infections

Pseudomonas /Physiology & structure Small gram-negative bacilli Strict aerobe Nonfermenter Simple nutritional requirements Mucoid capsule Oxidase positive = enterobactericeae > 10 species P. aeruginosamost common

Pseudomonas /Pathogenesis & immunity Multiple virulence factors  Structural components:  Toxins & enzymes pyocyanin  Antibiotic resistance

Pseudomonas /Pathogenesis & immunity Multiple virulence factors  Structural components: adhesins (e.g., flagella, pili, LPS, alginate capsule)  Toxins & enzymes exotoxin A, pyocyanin, pyoverdin, elastases, proteases, phospholipase C, exoenzymes S and T  Antibiotic resistance is inherently resistant to many antibiotics Can mutate to more resistant straines

Pseudomonas /clinical diseases Pulmonary infections (cystic fibrosis) Burn wound & other skin & soft tissue inf. UTI(Urinary tract infections) External otitis Eye inf. (contaminated contact lens cleaning fluids) Bacteremia & endocarditis

Pseudomonas / diagnosis & identification Culture  Simple Identification  Colonial morphology colony size, hemolysis, pigmentation, odor  Biochemical tests Positive oxidase test

Pseudomonas / diagnosis & identification Culture:  beta hemolysis,  green pigment,  grapelike odor  and simple biochemical tests (e.g., positive oxidase reaction; oxidative utilization of carbohydrates)

Pseudomonas / Combined use of effective antibiotics (e.g., aminoglycoside and β-lactam antibiotics) frequently required; monotherapy is generally ineffective and can select for resistant strains

Pseudomonas / Hospital infection-control efforts should concentrate on  preventing contamination of sterile medical equipment and nosocomial transmission;  unnecessary use of broad-spectrum antibiotics can select for resistant organisms

Pseudomonas / P. aeruginosa also produces a number of different β-lactamases that can inactivate many β-lactam antibiotics (e.g., penicillins, cephalosporins, and carbapenems).

P.aeruginosa

Burn wound infected with Pseudomonas

P.aeruginosa

Burkholderia (Formerly classified as Pseudomonas) B. cepacia, B. pseudomallei  Important human pathogens

Burkholderia cepacia Like P. aeruginosa is commonly associated with nosocomial infections relatively low level of virulence, rarely cause death is susceptible to trimetoprim- sulfamethoxazole

Burkholderia pseudomallei found in soil, water, vegetation opportunistic melioidosis “highly infectious”, ‘careful isolation’

“Stenotrophomonas maltophilia” “my favorite (the person or animal most people expect to win a race or competition) bacteria”

“Stenotrophomonas maltophilia” one of the most commonly isolated nonfermentative, gram-negative bacilli formerly classified as Pseudomonas, Xanthomonas infections in patients with impaired host defense mechanisms is resistant to commonly used  -lactams & aminoglycosides trimetoprim-sulfamethoxazole, is the agent most active

Acinetobacter oxidase-negative gram-negative coccobacilli

Acinetobacter A. baumannii, A. lwoffii, A. haemolyticus are recovered in nature & hospital survive on moist and dry surfaces (!skin!) resistant to antibiotics (carbepenems)!!!!!!!!!

Acinetobacter

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Moraxella

M.catarrhalis An important pathogen Strict aerobic Oxidase positive Gram negative diplococci

Moraxella Moraxella catarrhalis is the most important human pathogen common cause of bronchitis and bronchopneumonia, sinusitis, otitis most isolates are resistant to penicillin (produce  -lactamase)