Klebsiella- Enterobacter- Serratia Group @ 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 .

Differences of the Group Character Klebsiella Enterobacter Serratia Motility - + Indole Red pigment Quellung reaction

Klebsiella: a) K. pneumoniae . b) K. rhinoscleromatis. c) K. ozaenae. 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.