Obligatory anaerobic GN non- Virulence factors: General ... · capsule=antiphagocytic catalase and...
Transcript of Obligatory anaerobic GN non- Virulence factors: General ... · capsule=antiphagocytic catalase and...
Obligatory anaerobic GN non-spore forming bacteria:
Bacteroides fragilis (BF)
Prevotella; Porphyromonas, Fusobacterium, Veilonella spp. - coccus
General characteristics GN rods/cocci pleomorphic weakly stain with Gram Habitat: upper respiratory tract intestines, genitourinary tract
Virulence factors: capsule=antiphagocytic catalase and SOD=prevent intracellular killing cytotoxic enzymes=tissue damage, induction of inflammation SCFA= prevent intracellular killing toxin – BF enterotoxin (BFT) diarrhea
DISEASES – important characteristics: Polymicrobial=difficult to treatment adjacent to mucosal surfaces (unless extends) suppurative (abscesses common) endogenous=do not spread human-to-human, opportunistic, often iatrogenic=related to invasive medical procedures tissue necrosis, abscesses, putrid odor, suppurative secretions Predisposing factors: tissue ischemia, tissue necrosis, trauma, compromised vascular supply, surgery (especially in abdomen area e.g. gut surgery, genital tract surgery)
DIAGNOSIS •Microscopy •Culture (anaerobic conditions, selective media, longer culture 48-72 hs) Identification – biochemical tests NAATs (genome sequencing) Proteomic analysis (mass spectrometry
ANTIBIOTICS active metronidazole β-lactams (carbapenems, semisynthetic penicillins with β-lactamase inhibitors) clindamycin
Upper respiratory tract via traumatic introduction and extension chronic sinusitis and otitis media, periodontal diseases • Porphyromonas • Prevotella • Fusobacterium • non-BF species
Brain abscesses via direct extension or blood (rare) • Porphyromonas • Prevotella • Fusobacterium
Intraabdominal infections via surgery, direct extension • Prevotella • BF Peptostreptococcus (GP anaerobic coccus)
Gynecologic infections via direct extension, traumatic introduction PID, abscesses, endometritis, surgical infections
• Prevotella
Skin and soft tissue infections via bite and wound contamination (myonecrosis) • BF
Blood infections bacteremia not sepsis! • BF
Gastroenteritis enterotoxin-producing strain only • BF
GN fermentative and non-fermentative rods
Fermentative GN rods intestinal GN rods facultative anaerobes of Enterobacteriaceae family
Non-fermentative GN rods obligatory aerobic rods
Opportunistic: Escherichia coli Enterobacter spp. Proteus vulgaris, mirabilis Klebsiella pneumoniae
True pathogens: Salmonella Shigella Yersinia pathogenic E. coli strain
Reservoir: environment
Transmission: inhalation, inoculation, direct contact, contact with water
Reservoir: humans and animals intestines - environment
Transmission: inhalation, inoculation via insect bite, direct contact, endogenous infections
Opportunistic: Pseudomonas aeruginosa Acinetobacter baumanii Stenotrophomonas maltophilia
Burkholderia cepacia
General characteristics: GN rods ubiquitous in nature, present in soil, water, and are part of natural (intestinal rods) or transient (non-fermentative) flora of human organism Simple nutritional requirements; ferment (fermentative rods) or oxidize (non-fermentative rods) glucose
Common virulence factors: LPS (endotoxin), adhesive fimbria, most are motile, many possess capsule
Escherichia coli
Commensal=non-pathogenic
strains endogenous (opportunistic)
infections: Urinary tract infections (UTI) =UPEC (uropathogenic E. coli) Bacteremia/sepsis Intraabdominal infections
Pathogenic strains
gastroenteritis exogenous infections
Strains divided according to virulence factors into: EPEC = enteropathogenic E. coli ETEC = enterotoxigenic E. coli EIEC = enteroinvasive E. coli EHEC = enterohemorrhagic E. coli EAEC = enteroaggregative E. coli DAEC = diffusely adhering E. coli
Predisposing factors: perforation of intestines, surgery, weakened immune system, spreading from intestines in predisposed individuals (UTI)
Reservoir: animals and humans
Transmission to humans: food-borne, direct contact
EPEC = infantile diarrhea ETEC = traveler’s diarrhea EIEC = dysentery-like diarrhea EHEC = bloody diarrhea (HC=hemorrhagic colitis) +/- HUS=hemolytic uremic syndrome +/- TTP=thrombotic thrombocytopenic purpura EAEC = chronic diarrhea DEAC = diarrhea (chronic, acute), UTI
Exception: neonatal meningitis (encapsulated K1 strains=NMEC) from mother to newborn
Diagnosis: Microscopy Culture and identification How to detect pathogenic strains?
culture + serotyping how to detect toxins?
NAATs Virulence factors: (all present specific adhesion fimbria) EPEC - intimin+Tir = tight adherence to enterocytes ETEC – LT, ST enterotoxins EIEC – invasin EHEC – shiga toxin EAEC – cytotoxins and enterotoxins, adhesins DAEC = invasion, specific adhesins
Treatment: generally all infections caused by GN rods should be treated according to antimicrobials susceptibility
testing
Groups of antimicrobials active against GN rods: β-lactams, aminoglycosides, fluoroquinolones, TMP-
SMX etc.
Important! EHEC infections should not be treated with
antimicrobials
Yersinia – zoonotic infections
Y. pestis plague
Reservoir: rodents (rats, squirrels, rabbits, domestic animals)
Transmission to humans: flea bite (VECTOR), air-borne,
direct contact with animal tissue
Y. enterocolitica enterocolitis (mesenteric
lymphadenitis=pseudoappendicitis) Y. pseudotuberculosis
enterocolitis, Far East Scarlet-like Fever
Reservoir: animals
Transmission to humans: food-borne, blood transfusion
Complications: erythema nodosum reactive arthritis septicemia intraabdominal abscesses
PLAGUE bubonic (buboes) – flea bite (75% mortality) pneumonia – inhalation (>90%
m
VIRULENCE FACTORS LPS Intracellular survival (invasive bacteria) Resistance to phagocytosis Protein capsule Serum resistance Enzymes disturbing blood clotting
ortality) blood infection
septicemia
PLAGUE bubonic (buboes) – flea bite (75% mortality) pneumonia – inhalation (>90% m
VIRULENCE FACTORS LPS Intracellular survival (invasive bacteria) Resistance to phagocytosis Protein capsule Serum resistance Enzymes disturbing blood clotting
ortality)
VIRULENCE FACTORS LPS Intracellular survival (invasive bacteria) Resistance to phagocytosis Protein capsule Serum resistance
Enzymes disturbing blood clotting
TREATMENT Cephalosporins Aminoglycosides Chloramphenicol Tetracyclines
TMP-SMX
DIAGNOSIS Microscopy Culture – cold-tolerant Serotyping
TREATMENT Streptomycin Chloramphenicol Tetracyclines
TMP-SMX
SALMONELLA
Typhoid fever Gastroenteritis Gastroenteritis
S. Typhi, S. Paratyphi S. Choleraesuis S. Typhimurium, S, Enteritidis
BLOOD INFECTON (septicemia)
Reservoir: HUMAN only !!! Reservoir: animals, humans Reservoir: animals, humans
Transmission: person-to-person fecal-oral route
long-lasting carriage (gallbladder)
Transmission: fecal-oral route food-borne
Virulence factors: LPS Vi capsule
Enterotoxin Cytotoxin
Virulence factors: LPS, enterotoxin
Gallbladder - bile
Small intestine Invasion via M cells
(Payer patches)
Mesenteric lymph nodes - blood
Liver, spleen, bone marrow
High fever, rash
Shigella
Sh. dysenteriae – dysentery (shiga toxin) HUS
developing countries Sh. sonnei Sh. flexneri shigellosis – bloody diarrhea
Sh. boydii world-wide distribution
Transmission: person-to-person (fecal-oral route)
Reservoir: humans only !!!
Miscellaneous intestinal rods
Opportunists – endogenous infections
Proteus, Enterobacter, Citrobacter, Morganella, Serratia
Hospital-acquired (nosocomial) infections in newborns and immunocompromised
Klebsiella
K. pneumoniae: community-acquired (CA) necrotizing pneumonia Wound, soft tissue infections, UTI
K. granulomatis: sexually transmitted (SDT) or via traumatic introduction granuloma inguinale (donovanosis)
K. rhinoscleromatis and K. ozenae: chronic atrophic rhinitis (uncommon)
Pseudomonas aeruginosa
General characteristics: aerobic, ubiquitous in nature, produces pigments, not-fastidious, transient colonizer of upper respiratory tract, skin and gastrointestinal
tract in humans, inherently resistant to many antibiotics; treatment – combined therapy e.g. β-lactams+aminoglycosides; OPPORTUNITIC PATHOGEN
Virulence factors: capsule – antiphagocytic LPS toxic enzymes: proteases, phospholipase C, exoenzymes S and T – tissue damage, hemolysis pigments (pyocyanin) – induce inflammation EXOTOXIN A – inhibits host cell protein synthesis – kills host cells
Diseases: RTI: inhalation, intubation – tracheobronchitis, necrotizing bronchopneumonia Skin and soft tissue infections: traumatic inoculation, contamination – wounds (burns), hot tube folliculitis, ecthyma gangrenosum (during bacteremia) Bones: spreading from wound infection – osteochondritis UTI: in patients with urinary catheters Blood: blood catheters, contaminated infusion fluids – bacteremia, endocarditis Ear: contact with contaminated water – swimmer ear, malignant otitis externa Eye: traumatic inoculation (contact lenses) – corneal ulceration
Burkholderia Stenotrophomonas maltophilia Acinetobacter baumanii
OPPORTUNISTIC PATHOGEN B. cepacia – pneumonia, UTI, bacteremia B. pseudomalei (endemic Asia, Africa) –
inhalation, direct contact with soil, water, ingestion, traumatic inoculation: melioidosis (glanders); suppurative
cutaneous infections Susceptible to TMP-SMX
OPPORTUNISTIC PATHOGEN Pulmonary and blood infections traumatic inoculation (catheter),
contaminated infusion fluids, intubation, Uniformly resistant to carbapenems Susceptible to TMP-SMX
OPPORTUNISTIC PATHOGEN Pulmonary, wounds, blood infections – traumatic inoculation (catheter),
contaminated infusion fluids, intubation, wound contamination
Melioidosis (glanders) a rare contagious disease that mainly affects horses, characterized by swellings below the jaw and mucous discharge from the nostrils,
but may present generalized symptoms
Burkholderia pseudomalei - meloidosis
Answer questions – lecture 5; class 6 and 7: Non-spore forming anaerobes, fermentative and non-fermentative Gram-negative rods.
For all bacterial groups and species students should know: their habitats (reservoirs), sources and ways of transmission to humans, means of prevention
1. Name bacteria genera belonging to non-spore-forming anaerobes
2. What is the reservoir of non-spore forming anaerobes
3. What diseases non-spore forming anaerobes can induce?
4. Name virulence factors of non-spore forming anaerobes
5. What are factors predisposing to diseases caused by non-spore forming anaerobes
6. What are common characteristics of infections caused by anaerobes?
7. Name genera of bacteria included in Enterobacteriaceae family
8. Which genera of Enterobacteriaceae family include strict human pathogens?
9. What is the reservoir of GN fermentative rods?
10. How they are transmitted to humans?
11. Name virulence factors common to all GN fermentative rods
12. Name ways of transmission of GN fermentative rods strictly pathogenic to humans
13. Name pathovars (pathotypes) of E. coli pathogenic to humans
14. Name extraintestinal infections caused by E. coli
15. Name reservoirs and ways of transmission of E. coli strains causing intestinal infections in humans
16. Name exotoxins produced by E. coli causing intestinal infections in humans
17. Name Salmonella species and diseases they produce
18. Name reservoirs and ways of transmission of Salmonella species
19. What are virulence factors produced by Salmonella?
20. Explain patomechanism of typhoid fever
21. What patient’s samples should be send to the laboratory in case of salmonellosis and typhoid fever?
22. Name Shigella species
23. What is the reservoir of Shigella?
24. What are ways of transmission of Shigella to humans?
25. Name virulence factors of Shigella
26. What is a severe complication of shigellosis? Explain patomechanism
27. Name opportunistic species of Enterobacteriaceae family and diseases they produce
28. Name Klebsiella species and diseases they can produce in humans
29. Name Yersinia species and diseases they cause
30. Name reservoirs and routes of transmission of Yersinia species
31. What is reservoir of plague?
32. What are types of plague and how humans can acquire these types?
33. What disease is produced by Y. enterocolitica and Y. pseudotuberculosis?
34. What is the reservoir and the route of transmission of Y. enterocolitica to humans?
35. Name clinically important GN non-fermentative rods
36. Name virulence factors of Pseudomonas aeruginosa
37. Name diseases/infections caused by Pseudomonas aeruginosa
38. Why GN non-fermentative rods are considered opportunistic pathogens?
39. Name clinically important species of Burkholderia?
40. Characterize Stenotrophomonas maltophilia and Acinetobacter baumanii species