opportunistic enterobact
TRANSCRIPT
Fe A. Bartolome, MD, FPASMAP Department of Microbiology
Our Lady of Fatima University
• commensals of the large intestines
• infections found outside the intestines
• can infect any tissue of the body
• usual type of infection produced:
1.UTI 4. Meningitis
2.Wound infection 5. Septicemia
3.Pneumonia 6. GI disorders
Klebsiella-Enterobacter-Serratia Group
• Lactose fermenters EXCEPT Serratia group
• Give (+) Voges-Proskauer reactions presence of acetylmethyl carbinol
• Resistant to Ampicillin
Klebsiella
Characteristics:
1. Non-motile
2. Encapsulated – large polysaccharide capsule
3. Weak urease producer
4. Mucoid appearance of isolated colonies due to capsule
5. IMViC: - - + + TSI: A/A + gas
6. (+) test for lysine decarboxylase & citrate
Klebsiella
Klebsiella pneumoniae
• Friedlander’s bacillus
• Most commonly isolated member
• Present in respiratory tract & feces of about 5% of normal individuals
• Cause nosocomial or community-acquired infections
Klebsiella
Klebsiella pneumoniae
• Clinical:
Primary lobar pneumonia
Individuals with underlying medical problems
At risk: alcoholics & people with compromised pulmonary function
Extensive hemorrhagic necrotizing consolidation of lungs (+) blood-tinged, thick, non-putrid sputum
Klebsiella
Klebsiella pneumoniae
• Clinical:
Others: UTI, wound infection, bacteremia, meningitis, endophthalmitis
Klebsiella pneumoniae endophthalmitis
Klebsiella pneumoniae wound infection
Klebsiella
Klebsiella oxytoca
• Biochemically similar to K. pneumoniae but indole (+)
• Similar infection to K. pneumoniae
Klebsiella
Klebsiella ozaenae
• Fetid, progressive atrophy of mucous membranes of the nose chronic atrophic rhinitis
Klebsiella
Klebsiella rhinoscleromatis
• Rhinoscleroma – chronic granulomatous destruction of nose and pharynx
Enterobacter
• Also known as Aerobacter
• Usually nosocomially acquired
• Characteristics:
1.Motile
2.Usually non-encapsulated
3. (-) urease production
4.Citrate and ornithine decarboxylase (+)
5. IMViC: - - + + TSI: A/A + gas
Enterobacter
Enterobacter cloacae
• Cause majority of infections
• Most frequently associated with UTI
Enterobacter aerogenes
• With small capsules
• May be found free-living as well as in the intestinal tract
• Cause UTI and sepsis
Serratia
Characteristics:
1.Able to produce DNase, lipase and gelatinase
2.Resistant to Colistin and Cephalotin
3.Usually non-pigmented
4.Ferments lactose slowly
Serratia
Serratia marcescens
• Most frequently isolated
• Common opportunistic pathogen
• (+) production of bright red pigment (prodigiosin)
Serratia
Serratia marcescens
• Infections associated with:
1. Invasive procedures – IV catheterization, resp. intubation & urinary tract manipulation
2.Contamination of water in respiratory therapy devices
3.Narcotics addicts
Serratia
Serratia marcescens
• Diseases:
1.Pneumonia
2.Bacteremia
3.Endocarditis
4.Wound infection
5.Septicemia
6.Outbreaks of UTI
PROTEUS-MORGANELLA-PROVIDENCIA
PROTEAE
• Characteristics:
1. Deaminate phenylalanine produce phenylalanine deaminase
2. Motile
3. Grow on potassium cyanide medium (KCN)
4. Ferment xylose non-lactose fermenter
5. Urease (+)
6. Primarily cause UTI, both nosocomial and community-acquired
PROTEUS
• Active motility via peritrichous flagella (+) “swarming” on solid media (+) expanding rings (waves) of organisms over the surface of the agar
• Cell wall O antigens (OX-2, OX-19 & OX-K) of certain strains (P. vulgaris) cross react with several species of Rickettsiae (+) Weil-Felix test
• Present in human colon, soil and water
• Virulence factors:
1. Rapid motility at 370C
2. Urease production
Swarming gives rise to a very thin film of bacteria on the agar surface, but swarming periods are interspersed with periods when the cells stop and undergo a cycle of growth and division so that the colony has a distinct zonation, clearly seen in Fig. A. Ability to degrade urea to ammonia, by production of the enzyme urease (Figure B)
PROTEUS
Proteus mirabilis
• Causes most community-acquired & nosocomial infections
• 2nd leading cause of community-acquired UTI
• Inhibited by penicillins
• Indole (-)
PROTEUS
Proteus vulgaris
• Cause mainly nosocomial infection
• Indole (+)
• More resistant to antibiotics
• Treatment of choice: cephalosporin
Proteus
• Both Proteus vulgaris & Proteus mirabilis (+) H2S production blacken butt of TSI agar
• Diseases other than UTI: pneumonia, wound infection and septicemia
Morganella morganii
• Formerly Proteus morganii
• Urease (+)
• Cause nosocomial UTI
Morganella morganii panophthalmitis. The conjunctiva was haemorrhagic and necrotic with mucopurulent greenish pus discharge. The cornea was oedematous and opacified.
Providencia rettgeri
• Formerly Proteus rettgeri
• Member of normal intestinal flora
• Causes UTI
• Often resistant to antimicrobial therapy
CITROBACTER
• Formerly Bethesda-Ballerup group
• Citrate (+)
• Do not decarboxylate lysine
• Slowly ferment lactose
• Occur in environment and in human colon but majority of isolates from the urinary tract
• Can cause UTI and sepsis in immunocompromised patients
• Citrobacter diversus – most frequent isolate; also an important cause of neonatal meningitis and brain abscess
Diseases caused by members of the Enterobacteriaceae
Major pathogen Representative diseases Minor related genera
Escherichia UTI, traveler’s diarrhea, diarrhea, neonatal meningitis
Shigella Dysentery
Salmonella Typhoid fever, enterocolitis Arizona, Citrobacter, Edwardsiella
Klebsiella Pneumonia, UTI
Enterobacter Pneumonia, UTI
Serratia Pneumonia, UTI
Proteus UTI Providencia, Morganella
Yersinia Plague, enterocolitis, mesenteric adenitis
Gram-negative rods causing UTI or sepsis
Species Lactose fermented
Features of the organism
Escherichia coli + Greenish metallic sheen on EMB
Enterobacter cloacae + Usually nosocomial infections & often drug resistant
Klebsiella pneumoniae
+ Large mucoid capsule and viscous colonies
Serratia marcescens - Red pigment produced; nosocomial infections; drug resistant
Proteus mirabilis - Swarming phenomenon; produce urease
Pseudomonas aeruginosa
- Blue-green pigment; fruity odor; nosocomial; drug resistant
Lactose fermentation by members of the Enterobacteriaceae & related organisms
Lactose fermented rapidly
Lactose fermented slowly
Lactose not fermented
E. coli: motile; flat, nonviscous colonies
Edwardsiella, serratia, citrobacter, arizona, providencia, erwinia, vibrios
Shigella sp.: non-motile; no gas from dextrose
Enterobacter aerogenes: raised colonies; often motile; more viscous growth
Salmonella sp.: motile, acid & usually gas from dextrose
Klebsiella pneumoniae: very viscous, mucoid growth; non-motile
Proteus sp.: swarming on agar; urea rapidly hydrolyzed
Pseudomonas sp.: soluble pigments; sweetish smell
Triple sugar iron (TSI) agar reactions
Reactions RepresentativeGeneraSlant Butt Gas H2S
Acid Acid + - Escherichia, Enterobacter, Klebsiella
Alkaline Acid - - Shigella, Serratia
Alkaline Acid + + Salmonella, Proteus
Alkaline Alkaline - - Pseudomonas