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Why are non-entero GNR medically relevant?
- Small percentage of clinical isolates
- difficult to ID
- Frequent nosocomial agents (immunocomp, trauma introductions)
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What is the CDC ID scheme for non-entero GNR?
- MAC: growth vs no growth
- Oxidase: + vs -
- O/F test: oxidative/fermentative/asacchrolytic
- further testing: motility, nitrate reduction/denitrification, urease production, esculin hydrolysis, indole (using Ehrlich's reagent)
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Pseudomonas general (habitat, clinical imp, imp biochem, colony appearance, smell)
- habitat: common in env, especially water
- clinical: leading nosocomial agent of resp tract
- *P. aeruginosa is #1 clinically isolated non-entero GNR
- biochem: oxidase+
- colony: pearlescent appearance
- diff spp secrete diff pigments (P. aeruginosa is pyocyanin [blue-green])
- (SBA) spreading and flat w/ serrated edges, often B hemolytic
- *mucoid if taken from CF pt
- smell: cheap wine
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Pseudomonas aeruginosa - associated infections, virulence factors, ID method
- infections: Opportunistic pathogen (road rash, trauma)
- associated with CF pts
- Nosocomial infections (blood, wounds, trauma)
- swimmer's ear, ear infections, hot-tub folliculitis
- virulence: intrinsic resistance to many antibiotics
- Capsule (esp CF pts)
- motility, endotoxins, exotoxins
- ID: growth @ 42C
- carb oxidation+
- pearlescent colony appearance
- automated commercial systems
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Burkholderia cepacia - habitat, clinical imp, virulence factors, disease, ID characteristics
- habitat: ubiquitous in env (plants, soil, water)
- clinical: transmission via direct contact w/ contaminated medical devices
- can survive disinfectants, detergents, etc
- virulence factors: intrinsic resistance to many antibiotics
- elimination in CF pts is rare
- disease: pneumonia in CF patients (increased severity of disease in death) - fulminate lung diseaseendocarditis, UTIs, dermatitis, etc (rarely fatal)
- ID: produces a yellow pigment (SBA and burk. selective agar)
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Burkholderia pseudomallei - habitat, transmission, diseases, clinical imp, ID char
- habitat: soil, streams, rice paddies in Australia/Southeast Asia
- trans: inhalation or direct contact (trauma)
- disease: melioidosis (aggressive granulomatous pulmonary disease -> metastatic abscess formation on lungs/viscera -> overwhelming septicemia)
- pneumonia, orbital cellulitis, etc
- clinical: bioterrorism agent (mandatory report)
- ID: grows at 42C, gas from nitrate red+, old potato smell
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Acinetobacter baumanii - habitat, clinical imp, disease, ID char, virulence factors
- habitat: moist env, hospital env
- clin: nosocomial agent (assoc w/ ventilators, catheters)
- 2nd most common non-enteric GNR isolate
- disease: opportunistic pathogen (often involving debilitated pts)
- endocarditis w/ 22% mortality
- UTIs, resp tract, wounds, etc
- ID char: oxidase-, nonmotile, colonies may be tinted purple (false lactose on MAC)
- can appear as G+ cocci on smear!!!
- vir: can exhibit resistance to wide range of antibiotics
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Stenotropomonas maltophilia - habitat, clin imp, disease, ID char, virulence factors
- habitat: ubiquitous in water env, soil, plants, urine, resp secretions
- clin: major nosocomial agent (assoc w/ blood-draw, catheter, IV lines, breathing tubes, CF, transplantation)
- 3rd most commonly isolated non enteric GNR
- disease: bacteremia, resp inf, UTIs, wound infections, etc
- ID: oxidase-, lavender-green pigment (SBA), faint ammonia smell
- vir: inherent resistance to many antibiotics
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TCBS agar - purpose
- Thiosulfate Citrate Bile Salts agar
- used for selective siolation of cholera vibrios and Vibrio parahaemolyitics
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Campylobacter agars - purpose, types
- isolation/cultivation of campylobacter jejuni jejuni from human feces
- *campy is a Diva about growing (very slow, small)
- campy blood agar: includes antibiotics
- skirrows agar: slaked horse blood (X-factor), antibiotics
- campy CSM: columbia base, charcoal, hematin, antibiotics
- campy CVA: brucella base, defrinated sheep's blood, antibiotics
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Vibrio cholerae - habitat, diseases, vir factors, media req, ID, morphology, treatment
- habitat: brackish/marine water (need salt for growth) (aeromonas is fresh)
- disease: epidemics/pandemics of cholera
- V. vulnificus causes fatal septicemia in pts w/ liver disease
- other vibrio cause gastroent, wound inf
- vir: cholera toxin (CT)
- causes "rice water stools" (no blood)
- EXTENSIVE fluid loss, death without medical intervention
- *somatic Ag O1 and O139 are indicators of potential virulence
- media: only collected/tported in Cary-Blair media (others will be toxic)
- TCBS agar
- ID: yellow colonies on TCBS agar (normally green)
- string test+ (compared to Aeromonas)
- growth in 6.5% NaCl (compared to Aeromonas)
- ELISA
- morph: small, straight or CURVED bacilli
- treat: rehydration, vaccines for non-Us
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Aeromonas - habitat, diseases, groupings, media, ID, morph, treatment
- habitat: fresh water (vibrio is brackish)
- disease: gastroenteritis, bacteremia, wound infections, endocarditis, pneumonia, conjunctivitis, can lead to complications (HUS and kidney disease)
- psychrophilic grou: grow @22C, only A. salmonicida, FISH PATHOGEN, nonmotile
- media: resembles Yersinia on CIN agar (except oxidase+)
- ID: string test- (compared to Vibrio)
- no growth in 6.5%NaCl (compared to Vibrio)
- ELISA
- morph: single polar flagella
- treat: treatment for diarrhea not usually needed
- resistant to some antibiotics
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Campylobacter (habitat, spp, transmission, micro app, growth req, disease, treatment, ID, special considerations)
- habitat: normal flora (GI/repr) in various animals - pathogenic in humans
- spp: C. jejuni and C. coli are most commonly isolated
- transmission: contaminated milk, food, water (primarily chicken)
- *DOES NOT MULTIPLY IN FOOD
- micro: very small, curved (gull wings), GNB
- growth req: microaerophillic AND capnophilic conditions
- disease: gastroenteritis (#1 agent worldwide and US), febrile systemic disease, periodontal disease
- complications following infection include reactive arthritis and Guillain-Barre syndrome (demyelination of nerves)
- treat: self-limiting
- no standard for susc. testing
- ID: darting motility on wetmount
- small gull-wing faintly staining rods
- blood and WBCs in stool
- PCR
- considerations: special tport media must be used if >2hr delay (special growth reqs)
- req microaerophilic and capnophilic atmosphere
- variety of specialized media (to kill other stool bact)
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Helicobacter pylori - habitat, motility, similar to?, imp biochem, disease, ID, culture considerations, treatment
- habitat: inhabits human gastric mucosa (transmission unknown)
- >50% of adults 60+ infected
- colonizes mucosal layer, but DOES NOT invade epithelium
- motility: highly motile
- similar: originally name Campylobacter due to spiral-shaped morphology
- biochem: strong urease activity
- can persist for decades asymptomatically
- ID: urease test
- UB test uses radioactively labeled urea (can use biopsy if necessary)
- EIAs, molecular methods
- culture: various specialized media (including Thayer-Martin -normally for N. gonnorhea)
- VERY slow (can take >7days)
- incubation requires humidity and microaerophillic
- treat: triple-drug therapy due to frequent relapses and resistance development
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BCYE agar
- Buffered charcoal yeast extract
- used for isolation of Legionella spp
- *Ferric pyrophosphate and alpha-ketoglutarate req for Legionella spp
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Bordet-Gengou agar (or Regan-Lowe)
- used for detection/isolation of Bordetella pertussis
- *initially shiny colonies
- mostly replaced by PCR
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Haemophilus - habitat, micro app, culture req, diseases, ID, virulence factors
- habitat: normal flora of upper resp tract
- micro: g- coccobacilli, small
- culture: requires X and V factor
- *NOTE - H. parainfluenzae requires only V factor
- need immediate plating (suscep to drying)
- disease: H. aegypticus - conjunctivitis
- H. ducreyi - chancroid (painful) genitul ulcer
- H. parainfluenzae - endocarditis post dental work (rare)
- H. influenzae - bronchitis/pneumonia (elderly), sinusitis/otitis media (neonatal), meningitis (IMC)
- *NOTE - encapsulated strains are more serious, and typed based on capsule Ag
- H. influenzae type B (HIB) most common
- ID: MAC neg (will not grow)
- seen as satellite colonies near Staph on SBA (produces V factor)
- Horse blood bacitracin agar (HBBA) used to isolate H. influenzae from P. aeruginosa in CF samples
- agglutination tests, X/V factor discs, porphyrin test
- vir: resistant to numerous antibiotics
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Haemophilus - which spp indicate infection?
- H. influenzae and H. ducreyi indicate an infection
- H. aegypticus and H. parainfluenzae could be normal flora
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What are the members of the HACEK group?
- Aggregatibacter aphrophilus (used to be Haemophilus paraphrophilus)
- Aggregatibacter acinomycetmcomitans (used to be Actinobacillus actinomycetemcomitans)
- Cardiobacterium hominus
- Eikenella corrodens
- Kingella spp
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HACEK group - ____robic, habitat, disease
- all are capnophilic
- habitat: normal oral flora
- disease: endocarditis following mouth surgery (opportunistic)
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Aggregatibacter aphrophilus - habitat, disease, micro app
- habit: oral flora (dental plaque)
- disease: endocarditis
- micro: small coccobacillus (like Haemophilus) - diff by growth without X/V factors)
- **HACEK group
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Aggregatibacter actinomycetemcomitans - types, habitat, disease, colony morph
- types: serotypes based on surface polysaccharides
- hab: normal oral flora
- disease: endocarditis
- *associated w/ bites (boxers)
- colony: adhere to agar, distinctive star shape at center of colonies
- **HACEK group
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Cardiobacterium hominis - habitat, disease, micro app, colony morph
- habitat: oral flora, GI tract
- disease: endocarditis
- gram stain: arrange in "rosettes" or spindles
- colony: pitting (burrowing) associated w/ agar growth, adhere to agar
- **HACEK group
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Eikenella corrodens - habitat, disease, colony morph
- habitat: oral cavity commensal
- disease: endocarditis, bacteremia (least common cause of endocard in HACEK)
- assoc w/ bites, fights, and diabetics
- colony: yellow colonies, pitting, strong chlorine odor**HACEK group
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Kingella - spp, habitat, disease, micro app, colony morph
- spp: kingae, dentrificans, oralis
- habitat: colonize upper resp and Urogen
- disease: joint/bone infections (pediatric), endocarditis/wound infections
- micro: square ended bacilli (more than other HACEK), potential chaining
- colony: multiple types
- GROWS ON MTM (mistaken for N. gonorrhoeae)
- **HACEK group
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Brucella - transmission, spp, virulence factors, clin imp, imp biochem, disease, culture considerations, treatment
- trans: ZOONOTIC disease, ingestion of unpasteurized milk, inhalation of aerosolized particles, direct contact w/ infected animals
- spp: melitensis, abortus, suis, canis
- vir: intracellular pathogens (phagocytes)
- clin: possible bioterrorist agent (easily aerosolized, moderate morbidity)
- biochem: H2S production
- disease: 3 stages of undulant fever
- acute - fever, malaise, myalgia... w/in 8 wks
- subchronic (undulant) - fluctuating fever, arthritis... w/in 1 year
- chronic: arthritis, chronic fatigue.. 1+ year after
- localizes in erythritol-rich tissue (placenta = abortions)
- culture: very slow growth (grow for 3 weeks)
- requires humidity and slight CO2
- 5% heated horse/rabbit serum enhances growth
- treat: 6 week course of M0 penetrating antibiotics to prevent reinfection
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Legionella - ___robic, spp, transmission, habitat, disease, preferred spec, culture considerations, ID,
- strict aerobes
- spp: 52+ spp (L. pneumophilia - 16 serotypes - is predominant pathogen)
- transmission: aerosols
- habitat: ubiquitous in env, aquatic env, AC ducts, plumbing systems, etc
- can survive extreme ranges of heat (can multiply within certain amoebae)
- disease: Legionnaire's disease (pneumonia 10-20% fatal, sporadic/endemic/epidemic), Pontiac (respiratory) fever (self-lmiting), would abscesses, endocarditis
- *mostly IMC, 60+, or heavy smokers
- spec: sputum > pleural/blood/biopsy
- deliver within 30 minutes of collection to avoid overgrowth by others
- culture: STRICTLY AEROBIC
- 2 plates used - BCYE w/o inhibtory agents and BCYE w/ antibiotics
- growth in 2-4 weeks
- ID: ground glass appearance on BCYE ("grainy"), serodiagnosis from ref lab
- *AST not indicitative of in-vivo response to therapy (not helpful)
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Bordetella - habitat, spp, disease, virulence factors, culture considerations, ID, treatment
- habitat: ONLY INFECTS HUMANS (no reservoir)
- spp: B pertussis, B. parapertussis
- disease: pertussuis (whooping cough)
- highly contagious via droplets from cough
- 3 stages...
- catarrhal - mild cold symptoms
- paroxysmal - many episodes of violent coughing per day, vomiting, "whooping" sound when air is rapidly inhaled past swollen glottis
- convalescent - lymphocytosis w/o fever
- vir: Pertussis toxin (PT) - disrupts cell ability to "call for help" or "receive help" via signals
- adhesins - attach bacteria to ciliated cells
- cytotoxin - paralyzes cilia
- culture: recovery from resp spec requires addition of other factors
- Bordet-Gengou potato infusion, Regan and Lowe
- ID: B. parapertussis can grow on MAC (B. pertussis cannot), colonies appear as "drops of mercury"
- treatment: vaccine available
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