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Klebsiella- Enterobacter- Serratia Group Klebsiella: @ Gram negative rods, non-motile, aerobic and facultatively anaerobic @ Catalase positive, oxidase negative, @ Attacks sugars fermentatively, usually with gas production @ KCN positive, VP positive
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Klebsiella- Enterobacter- Serratia Group Klebsiella: @ Gram negative rods, non-motile, aerobic and facultatively anaerobic @ Catalase positive, oxidase negative, @ Attacks sugars fermentatively, usually with gas production @ KCN positive, VP positive @ Ornithine decarboxylase negative, @ Urease positive, phenylalanine negative.
Enterobacter: @ Gram negative rods, motile, aerobic and facultatively anaerobic @ Catalase positive, oxidase negative @ Attacks sugars fermentatively, gas is produced @ VP positive, gluconate positive, gelatin liquefied slowly @ Ornithine decarboxylase positive.
Serratia: @ Gram negative rods, motile, aerobic and facultatively anaerobic @ Catalase positive, oxidase negative, @ Attack sugars fermentatively, often with gas production @ VP usually positive, gluconate positive, ornithine decarboxylase positive, @ Deoxyribonuclease positive, @ Produce a red pigment .
SPECIES: Klebsiella: a) K. pneumoniae . b) K. rhinoscleromatis. c) K. ozaenae. Enterobacter: a) E. cloacae. b) E. aerogenes. Serratia: S. Marcescens Edwin Klebs (1834-1913) – Described Klebsiella
PATHOGENICITY: @ All three organisms produce an endotoxin that leads to septic shock. @ K. pneumoniae produces a large capsule that has an antiphagocytic action. @ Enterobacter and Serratia are opportunistic organisms.
Epidemiology: @ Predisposing factors to Klebsiella infection are: old age, respiratory disease, diabetes, and alcoholism. @ Klebsiella carrier rate in the respiratory tract is 10% of normal people. @ Enterobacter and Serratia infections occur following catheterization, intubation, & urinary tract procedures. @ Serratia infection outbreaks occur after using contaminated water in respirators
Clinical findings: @ Infections produced by all members of the group are UTI, pneumonia, bacteraemia, and meningitis. @ K. pneumoniae causes pneumonia with a thick, bloody sputum that progresses to necrosis and abscess formation. @ K. ozaenae, causes atrophic rhinitis. @ K. rhinoscleromatis, causes destructive granuloma of nose & pharynx
LABORATORY DIAGNOSIS: • Specimens collected: • @ Urine, sputum, pus, infected tissue. • Microscopy: • @ Gram negative rods: • a) Klebsiella is non-motile, has a big • capsule. • b) Enterobacter and Serratia are motile, • and non-capsulated.
Culture: @ Media are Mac Conkey, blood agar. @ Klebsiella produces mucoid colonies, and lactose fermenters. @ Enterobacter gives similar colonies as Klebsiella, but not so mucoid. @ Serratia are non-lactose fermenters. Produces red pigment when grown on nutrient agar at room temperature.
Biochemical reactions: • @ Members of the group are similar in most • biochemical reactions. • @ They are differentiated by motility, indole, • pigment production, & quellung reaction. • Antisera: • @ Pooled antisera to detect monovalent • specific O and K antigens by slide • agglutination.
Prevention @ Some hospital-acquired infections caused by these rods are prevented by general measures such as: # Changing the site of intravenous catheters # Removing urinary catheters when they are no longer needed # Proper care of respiratory devices. @ There is no vaccine.
TREATMENT @ This depends on the site of disease and the resistance pattern of the isolate: # For hospital-acquired infections give empirically cefotaxime or gentamicin until sensitivity tests are back. # In severe Enterobacter infections, a combination of gentamicin and imipenem may be given.