bacte lec - non-fermentative Gram-negative bacilli (new)

Nonfermenters

Group of Gram negative bacilli that do not ferment glucose and other sugars

(+) positive

Oxidase test result of nonfermenters (except Acinetobacter spp.)

Pseudomonas

→ strictly aerobic
→ catalase-positive, oxidase-positive (except P. luteolus and P. oryzihabitans)
→ motile, some have polar flagella

Pseudomonas aeruginosa

→ most common pseudomonas
→ ound in moist environments, pools, hot tubs, catheters, and humidifiers in hospitals (ubiquitous)
→ opportunistic pathogen, and causes nosocomial infection

slime polysaccharide, endotoxin, proteases, anti-complementary, exotoxin A, pili, alginate

Pathogenesis/ Virulence of P. aeruginosa

exotoxin a

promotes cellular damage and tissue invasion and is toxic for macrophages, blocks protein synthesis

Pili

(P. aeruginosa) found on bacterial surface, mediate attachment to host cells

alginate

a polysaccharide, polymer that inhibits phagocytosis and contributes to the infection potential in patients with cystic fibrosis

Pyocyanin, Pyoverdin, Pyorubin, Pyomelanin

pigments of P. aeruginosa

Pyocyanin

water-soluble, bright bluish phenazine pigment, damages cells by producing reactive oxygen species

Pyoverdin

green, water-soluble and fluoresces under short- wavelength ultraviolet light

Pyorubin

red pigment of P. aeruginosa

Pyomelanin

brown pigment of P. aeruginosa

Pseudomonas aeruginosa

Common cause of lung infection in people with Cystic fibrosis

Jacuzzi or hot tub syndrome

What syndrome is caused by P. aeruginosa which manifests as necrotizing rash in divers and swimmers?

Ecthyma gangrenosum

A disease caused by P. aeruginosa

Gram negative, medium-size, straight rods

Gram staining, size, and shape of P. aeruginosa

5% Sheep blood agar, MacConkey agar, thioglycolate broth, brain-heart infusion broth

Culture Media of choice for cultivation of P. aeruginosa

Cetrimide agar

a selective and differential medium for the identification of P. aeruginosa

Cetrimide

acts as a detergent and
inhibits most bacteria; enhances production of pigments

green

colornies of P. aruginosa on Cetrimide agar

B-hemolytic, rough or ground glass appearance

colonies of P. aeruginosa on sheep blood agar

Pseudomonas aerugionosa

formation of sheen and/or pigment on the slants of TSIA and Pseudomonas P agar, Mueller-Hinton agar, Trypticase soy agar

oxidase +, ADH +, citrate +

results of P. aeruginosa in oxidase test, Arginine dihydrolase (ADH) test, citrate test

alkaline slant/neutral butt

P. aeruginosa reaction in TSIA

42C

The temperature in which P. aeruginosa grows

musty grape-like (or corn tortilla), 2-aminoacetophenone

What is the odor of P. aeruginosa? What causes this odor?

aminoglycosides, the carboxypenicillins and ureidopenicillins, ceftazidime (or cefepime), carbapenems, the
quinolones

Antimicrobial susceptibility of P. aeruginosa: Susceptible

sulfamethoxazole- trimethoprim (SXT) and tetracyclines, tigecycline,
ertapenem, nitrofurantoin

Antimicrobial susceptibility of P. aeruginosa: Resistant

colistin, polymyxin B

Antimicrobial susceptibility of P. aeruginosa: Multiple resistant strains

Pseudomonas aeruginosa, Pseudomonas fluorescens, Pseudomonas putida, Pseudomonas veronii, Pseudomonas monteilii, Pseudomonas mosselii

Fluorescent pseudomonads

Pseudomonas stutzeri, Pseudomonas mendocina, Pseudomonas pseudoalcaligenes, Pseudomonas alcaligenes, Pseudomonas luteola, Pseudomonas oryzihabitans

Nonfluorescent pseudomonads

Pseudomonas putida

→ A psudomonas specie associated with catheter-related sepsis in cancer patients
→ A pseudomonas specie that has low virulence, rarely causes clinical disease
→ A pseudomonas specie that is gelatin hydrolysis negative

Pseudomonas fluorescens

→ Pseudobacteremia related to contaminated catheters and catheter-related devices
→ A pseudomonas specie that is gelatin hydrolysis positive

Pseudomonas stutzeri

→ A pseudomonas specie that is rarely isolated, rarely causes infection. It is wrinkled, leathery, adherent colonies that may produce a light-yellow or brown pigment.
→ A pseudomonas specie that is ADH (-) and starch hydrolysis (+)

Acinetobacter

→ short, rod shaped to spherical Gram negative bacilli
→ non motile and strictly aerobic
→ difficult to decolorize in Gram stain, more that 25 species are known but differentiation biochemically is difficult

Acinetobacter calcoaceticus - Acinetobacter baumanii complex

Acinobabcter is often collectively known as

oxidase -, catalase +

Acinetobacter oxidase test, and catalase test results

purplish

color of Acinetobacter colonies in MacConkey's agar

Acinetobacter baumanii

glucose-oxidizing (saccharolytic), nonhemolytic Acinetobacter

Acinetobacter Iwoffi

non-glucose oxidizer (nonsaccharolytic), nonhemolytic Acinetobacter

Acinetobacter haemolyticus

nonsaccharolytic, hemolytic acinobacter

trimethoprim-sulfamethoxazole, quinolones, ureidopenicillins, imipenem, ampicillin-sulbactam, ceftazidime, carbapenems (except ertapenem)

Acinetobacter baumanii complex is susceptible to

β-lactam, aminoglycoside antibiotics

Acinetobacter baumanii complex is resistant to

plasmid-mediated acetyl-, adenylyl-, phosphotransferases

Resistance of Acinetobacter baumanii complex to the
aminoglycosides is caused by __________

CRAB (carbapenem-resistant Acinetobacter baumanii)

resistant to all classes of antibiotics, except colistin and tigecycline

Stenotrophomonas maltophilia

→ third most common nonfermentative, Gram negative bacilli isolated in the clinical laboratory
→ nonmotile, nosocomial pathogen

mechanical ventilation, use of broad-spectrum antibiotics, catheterization, neutropenia

Risk factors for colonization or infection (S. maltophilia)

oxidase -, DNAse +, catalase +, esculin and gelatin hydrolysis +, Lysine decarboxylase +

S. maltophilia results on oxidase test, DNAse test, catalase test, esculin and gelatin hydrolysis, Lysine decarboxylase

blood agar plate, MacConkey agar

culture media for Stenotrophomonas maltophilia

lavender green colonies

color of S. maltophilia colonies on Blood agar plate

bluish

color of S. maltophilia colonies on MacConkey agar

Trimethoprim-sulfamethoxazole

antibiotic of choice for Stenotrophomonas maltophilia

Burkholderia

Aerobic, non-spore-forming, all are motile polar flagella except for 1 specie, nosocomial

Burkholderia mallei

Burkholderia specie that is nonmotile _____________

Burkholderia pseudomallei

Burkholderia that is acquired via inhalation or contact through cut or abraded skin

Melioidosis

Burkholderia pseudomallei causes what illness

Burkholderia pseudomallei

nonfermentative, wrinkled colonies, bipolar staining in gram stain

earthy

odor of Burkholderia pseudomallei

Ashdown's medium

selective culture medium for the isolation and characterization of Burkholderia pseudomallei

colistin

inhibitor in Ashdown's medium

neutral red

indicator in Ashdown's medium responsible for deep pink Burkholderia pseudomallei colonies

Burkholderia cepacia complex

→ Nosocomial pathogen associated with contaminated equipment, medications, disinfectants
→ Can cause bacteremia, UTI, septic arthritis, respiratory tract infection
→ Opportunistic pathogens in patients with cystic fibrosis and Chronic granulomatous disease

Burkholderia mallei

nonmotile, growth on MAC, Variable glucose oxidation, (+) ADH, Reduce nitrates to nitrites

Glanders

Burkholderia mallei causes what disease

livestock (horse, mule, donkey)

Burkholderia mallei primarily affects

Burkholderia mallei

parasite that causes an infection in humans, May cause severe local suppurative or acute pulmonary infections

Aeromonas

Facultative anaerobes, widely distributed in freshwater, estuarine, and marine environments

Septicemia, wound infections

(Aeromonas) Extraintestinal infections:

Mesophilic Group

Optimal growth at 37 degrees celsius, A. hydrophilia complex, A. veronii complex, A. caviae complex

Psychrophilic group

Optimal growth at 22 degrees celsius, A. Salmonicida

Aeromonas

pink-centered colonies from the fermentation of mannitol

Aeromonas hydrophlia

An infection in fish which manifests as iridial hemorrhage, external/internal hemorrhage, reddened fins, adipose fin clipped

Moraxella

→ nonmotile, strongly oxidase (+), strictly aerobic, asaccharolytic
→ opportunists that reside on the mucous membranes of humans and lower animals

penicillin

An example of antibiotic that moraxella is susceptible to

Moraxella catarrhalis

→ Most frequent isolate, COMMENSAL of the upper respiratory tract of humans; respiratory and ear specimens
→ resembles neisseria due to Gram-negative coccal morphology
→ previously called Neiserria catarrhalis and also Branhamella catarrhalis

Moraxella

Smooth, opaque, gray-to-white colonies,

hockey puck

description of Moraxella colonies because the colony remains intact when pushed across the plate with a loop

SBA, CHOC agar

culture media for moraxella

Moraxella nonliquefaciens

Second most frequently isolated, normal flora of the respiratory tract of humans, does not grow on MAC

Moraxella ostoensis

part of the normal flora in the genitourinary tract, and similar morphologically and biochemically to M. nonliquefaciens

Moraxella lacunata

common conjunctival isolate

Oligella

Small, paired, Gram negative bacilli or coccoid, do not grow on MAC, and non-oxidative

Oligella ureolytica

motile by petrichous flagella

Alcaligenes

→ Found in water, and is resistant to disinfectants such as chlorhexidine and quaternary ammonium compounds
→ Obligate aerobe, and is Grown on MAC
→ Motile with 1-12 peritrichous flagella

eye infections, pancreatic abscesses

Alcaligenes faecalis is linked to what illnesses?

Achromobacter xylosoxidans

Most commonly isolated from this genus, Achromobacter

Chromobacterium violaceum

Reservoirs are soil and water

Skin lesion

Common portal of entry of C. violaceum

Violecein

Pigment produced by C. violaceum

Flavobacteriaceae

Which bacteria hydrolyzes esculin and is indole positive?

Elizabethkingia meningoseptica

What spp. causes meningitis and septicemia in newborns?

Ralstonia

This nonfermentative bacteria is a slow grower requiring 72 hours to grow on primary cultures

Sphingomonas

This bacteria does NOT grow on MAC and needs more than 48 hours for colonies to grow on SBA

Haemophilus

- Carbohydrate fermenter
- Requires X and V factors to grow

Aggregatibacter

- Major contributor to periodontitis
- Star shaped colonies at 48 hours
- Glucose fermenter
- Does not grow on MAC

Eikenella corrodens

- Acquired from human bites/fights
- High susceptibility to people with poor dental hygiene
- Bacilli pits on the surface of the agar

Kingella kingae

- Causes indolent, slowly progressive endocarditis
- Most common cause of osteoarthritis in children under 4 years old
- Grows on Neisseria Selective Agar

Cardiobacterium hominis

- Does not grow on MAC
- Grows in the absence of X and V factors
- Microaerophilic, facultative, anaerobe
- Characteristic rosette formation

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