Pseudomonas, other gram negative rods Flashcards
Pseudomonas aeruginosa
Habitat
Transmission
Habitat: Commonly living in the external environment in moist areas.
In hospitals, found on sinks, respiratory equipment, kitchens, bathrooms, sinks. even on disinfectants because it is so resistant.
Is also a member of the normal GI flora.
Transmission: Opportunistic pathogen that only infects immunocompromised patients.
4 major routes of infection: Catheters, Canulas, Surgical wounds, Endotracheal tubes.
Can live in very versatile environments, from Distilled water to very high salt concentrations. Can live in solutions of waek antiseptics and many antibiotics.
Pseudomonas aeruginosa
Morphology
Culture
Gram negative rods (long, 1.5-3uM) in pairs, with flagella at one or both poles.
Obligate aerobic (AERuginosa)
Beta-hemolytic on blood agar around smooth, mucoid colonies
Produces acid from glucose only in the presence of O2. So O/F medium test is part of its diagnosis
EMB agar: lactose negative
Simple agar: Fluroescent green pigment to the colonies, blue pigment which diffuses into the agar, dark red pigment, and black pigment.
Produces a sweet-smelling grape or corn like odor.
Grows at 42C
Oxidase positive.
Pseudomonas aeruginosa
Diagnosis
Sample and culture - culture characteristics
Direct stain of smear
MALDI-TOF mass spec.
Oxidase positive
Lactose negative
for epidemiological investigations:
Phage typing - bacteriophages will only effect a single strain of a given bacterial species, and thus are used to identify the specific strain.
Pyocin-typing, different strains secrete different specific Pyocins, which is a pigment protein that interferes with mitochondrial respiration, it is a virulence factor.
PFGE - Pulsed feild gel electrophoresis. Different bacteria give different specific patterns.
Psuedomonas aeruginosa
Virulense factors
Adhesins
Fimbriae
Capsule
Alginate slime formation
Invasins
Genetic factors: Drug resistance plasmids and R factors
Flagella
Exotoxin A - like diptheria toxin, inhibits peptide transcription and kills the cell.
LPS
Antiphagocytic surface properties
Defense against serum bactericidal reaction (complement + Ig) - slime layer, capsule, LPS, proteases
Defense against immune responses - Slime layer, Capsule, Protease enzymes
P. aeruginosa
Clinical diseases
Strictly Nosocomial infections of immunocompromised patients.
BE PSEUDO (+2)- The diseases caused
Burn infections (infecting a burn wound)
Endocarditis
Pneumonia
Sepsis
Eye infections
UTI
Diabetic osteomyelitis - (osteomyelitis - bone infection by aeruginosa, specifically infecting down to the bone through an already existing diabetic woulnd, usually in the foot.)
External otitis media
Lung colonisation in cystic fibrosis patients.
P aeruginosa
Treatment
These are extremely resistant to many antibiotics. Some strains are panresistant - MRPS
Antibiogram.
They can mutate over the course of treatment and rapidly acquire resistance to the antibiotic being used.
Carbapenems, aminoglycosides, 3rd generation cephalosporin.
Colistin
Burkholderia cepacia
Morphology
Culture
A multiple-species group of bacteria that for the Burkholderia cepacia complex.
All are gram negative, aerobic rods (bacilli)
Multitrichous polar flagella
Like pseudomonas aeruginosa, they are very adaptable, and can live in many environments
plants, soil, around plant roots
High intrinsic antibiotic and disinfectant resistant: so they are common contaminants of pharmaceutical solutions, weak antiseptic solutions, and medical equipment, like nebulizers and breathing apparati.
Burkholderia
Habitat
Transmission
Burkholderia
Clinical disease
Infects immunocompromised patients. In CF patients, Catheterized patients, Cannulated patients, or as an opportunistic pathogen to other open wounds immunocompromized patients –> septic arthritis, peritonitis, pneumonia.
Cystic fibrosis patients are at highest risk. -
in CF patients:
can be asymptomatic,
chronic respiratory infection,
chronic granulomatosus disease,
brochiectasis (airway dilation),
rapidly progressing pneumonia and bacteremia.
Burkholderia capecia
Diagnosis
Treatment
OF +/- (like aeruginosa) Oxidation positive / Fermentation negative
Blood agar, EMB agar. Requires long incubation period
high inherent resistance to aminoglycosides and polymyxins, and often beta-lactams : antibiogram.
Treat with: trimethoprim-sulfamethoxide, meropenem, 3rd gen cephalosporins.
Burkholderia mallei
Habitat
Transmission
Diagnosis
Glanders is a horse disease, which causes ulcers
Begins as an ulcer, then lymphadenoma and sepsis.
Usually fatal septicemia.
If it is inhaled it can lead to primary pneumonia and then sepsis.
It is very infections
Diagnosed by Strauss reaction: Inject a male guinea pig, causes orchitis, swollen testicles, then pyogneic intraperitoneal infection and death.
Burkholderia pseudomallei: melioidosis
Another soil bacteria like Burkholderia capacia
Found in tropical regions, africa, and australia
Infection can occur and be dormant for many years then appear during stress.
Potential bio-weapon like the other burkholderia.
Stenotrophomnas maltophilia
Morphology
Culture
Gram negative rod
the third most common pathogen found colonizing the lungs of Cystic Fibrosis patients.
Strenotrophomonas maltophilia
Habitat
Transmission
Diseases
Habitat:
Contaminated hostpital equipment and plastic devices
Ice machines, sinks, weak disinfectant solutions
Common nosocomial opportunistic pathogen
Pneumonia,
Bacteremia
Meningitis
UTI
Wound infections.
Strenotrophomonas maltophia
Diagnosis
Treatment
Cultivation: blood agar, EMB agar,
Oxidase negative
Very resistant to many drugs, including carbapenems, antibiogram,
Usually trimethoprim + sulfamehtoxazole
