Opportunistic Enterobacteriaceae OPPORTUNISTIC INFECTIONS OF ENTEROBACTERIACEAE ØGRAM

Opportunistic Enterobacteriaceae

OPPORTUNISTIC INFECTIONS OF ENTEROBACTERIACEAE ØGRAM NEGATIVE SEPSIS ØURINARY TRACT INFECTIONS ØPNEUMONIA ØABDOMINAL SEPSIS ØMENINGITIS ØSPONTANEOUS BACTERIAL PERITONITIS ØENDOCARDITIS

OPPORTUNISTIC INFECTIONS (cont. ) GRAM NEGATIVE SEPSIS ØLife-threatening ØUsually nosocomial ØCommonly caused by E. coli PATHOGENESIS: Early Phase (REVERSIBLE) Decreased arterial resistance; Increased cardiac output Kinins (protein vasodilators & mediators of inflammation) in plasma due to tissue damage, endotoxin, AG-AB complexes Second Phase (REVERSIBLE) Increased arterial resistance; Decreased cardiac output Third Phase (IRREVERSIBLE) Vascular collapse with organ failure Endotoxin induced DIC, hemorrhage and death

OPPORTUNISTIC INFECTIONS (cont. ) URINARY TRACT INFECTIONS Ø Usually ascending infection, not hematogenous route Ø Greatest incidence in young & middle-aged females Ø Incidence increases with age in males Ø Most commonly caused by E. coli Ø Diagnosis by microscopic & cultural exam of urine Ø Obtain urine by catheter through urethra into bladder, clean catch midstream (CCMS) or suprapubic tap PNEUMONIA Ø Nosocomial; Spread by personnel and equipment Ø Frequently caused by K. pneumoniae Ø Often in middle-aged males who abuse alcohol Ø Difficult to diagnose due to commensals in sputum

OPPORTUNISTIC INFECTIONS (cont. ) ABDOMINAL SEPSIS ØCaused by flora of the GI tract ØInfections usually polymicrobial MENINGITIS ØUsually nosocomial ØFrequently caused by E. coli ØDiagnosis by microscopic & cultural exam of CSF

OPPORTUNISTIC INFECTIONS (cont. ) SPONTANEOUS BACTERIAL PERITONITIS ØUsually in patients with liver ailments ØCommonly caused by E. coli, but also anaerobes & Gram-positive cocci (S. pneumoniae) ENDOCARDITIS ØVascular endocardial surface inflammation ØMostly caused by Gram-positive cocci, but 1 -3% caused by aerobic Gram-negative rods ØDiagnosis by blood culture ØDifficult to treat; Treatment is of long duration

Virulence Factors Associated with Enterobacteriaceae Common Virulence Factors ØEndotoxin ØCapsule ØAntigenic phase variation ØSequestration of growth factors ØResistance to serum killing ØAntimicrobial resistance Factors Associated with Specific Pathogens ØExotoxin production ØExpression of adhesion factors ØIntracellular survival and multiplication

Endotoxin-Mediated Toxicity Ø Fever Ø Leukopenia (reduced # of WBCs) (<5000/mm 3) followed by leukocytosis (increased # of WBCs)(>10 -12, 000/mm 3) Ø Activation of complement Ø Thrombocytopenia (reduced # of platelets) Ø DIC (Disseminated intravascular coagulation) Ø Decreased peripheral circulation and perfusion (blood flow) to major organs Ø Shock Ø Death

See Handout on Enterobacteriaceae General Information

Summary of Escherichia coli Infections

Summary of Escherichia coli Infections (cont. )

Gastroenteritis Caused by E. coli

Specialized Virulence Factors Associated with E. coli ETEC EAEC UPEC EPEC UPEC EIEC UPEC ETEC EHEC UPEC ETEC Type 1 pili

Fimbriated Bacterial Cell F = Flagellum Note: All other appendages are fimbriae (a. k. a. , pili)

Afimbriated Bacterial Cells Nonadherent Afimbriated Bacterial Cells and Buccal Cells

Fimbriated Bacterial Cells Adherent Fimbriated Bacterial Cells and Buccal Cells

Heparin-binding epidermal growth factor on heart & nerve surfaces (ETEC) (EHEC)

REVIEW

OPPORTUNISTIC INFECTIONS OF ENTEROBACTERIACEAE ØGRAM NEGATIVE SEPSIS ØURINARY TRACT INFECTIONS ØPNEUMONIA ØABDOMINAL SEPSIS ØMENINGITIS ØSPONTANEOUS BACTERIAL PERITONITIS ØENDOCARDITIS REVIEW

Virulence Factors Associated with Enterobacteriaceae Common Virulence Factors ØEndotoxin ØCapsule ØAntigenic phase variation ØSequestration of growth factors ØResistance to serum killing ØAntimicrobial resistance Factors Associated with Specific Pathogens ØExotoxin production ØExpression of adhesion factors ØIntracellular survival and multiplication REVIEW

See Handout on Enterobacteriaceae General Information REVIEW

Endotoxin-Mediated Toxicity Ø Fever Ø Leukopenia (reduced # of WBCs) (<5000/mm 3) followed by leukocytosis (increased # of WBCs)(>10 -12, 000/mm 3) Ø Activation of complement Ø Thrombocytopenia (reduced # of platelets) Ø DIC (Disseminated intravascular coagulation) Ø Decreased peripheral circulation and perfusion (blood flow) to major organs Ø Shock Ø Death REVIEW

Summary of Escherichia coli Infections REVIEW

Summary of Escherichia coli Infections (cont. ) REVIEW

Gastroenteritis Caused by E. coli REVIEW

Fimbriated Bacterial Cell F = Flagellum Note: All other appendages are fimbriae (a. k. a. , pili) REVIEW

Afimbriated Bacterial Cells Nonadherent Afimbriated Bacterial Cells and Buccal Cells REVIEW

Fimbriated Bacterial Cells Adherent Fimbriated Bacterial Cells and Buccal Cells REVIEW

REVIEW

Heparin-binding epidermal growth factor on heart & nerve surfaces (ETEC) (EHEC) REVIEW