Enterobakter
Enterobakter
Enterobakter
Enterobacteriaceae
Small Gram-negative rods Most motile with peritrichous flagella
Shigella and Klebsiella are nonmotile
Oxidase-negative facultative anaerobes Reduce nitrate Ferment glucose and other carbohydrates Many genera
Escherichia, Salmonella, Shigella, Klebsiella, Proteus, Enterobacter, Yersinia, etc.
Enterobacteriaceae
Family Enterobacteriaceae often referred to as enterics Four major features:
All ferment glucose (dextrose) All reduce nitrates to nitrites All are oxidase negative All except Klebsiella, Shigella and Yersinia
are motile
Ability to colonize, adhere, produce various toxins and invade tissues Some possess plasmids that may mediate resistance to antibiotics Many enterics possess antigens that can be used to identify groups
O antigen somatic, heat-stable antigen located in
the cell wall H antigen flagellar, heat labile antigen K antigen capsular, heat-labile antigen
Based on clinical infections produced, enterics are divided into two categories:
Opportunistic pathogens normally part of
the usual intestinal flora that may produce infection outside the intestine Primary intestinal pathogens Salmonella, Shigella, and Yersinia sp.
(Fimbriae)
Structure of Lipopolysaccharide
Structure of Lipid A
Hydrophobic
EXOTOXIN
ENDOTOXIN
1. Released from the cell before 1. Integral part of cell wall or after lysis
2. Protein
3. Heat labile 5. Toxoids can be produced 6. Specific in effect on host 7. Produced by gram-positive and gram-negative organisms
2. Endotoxin is LPS; Lipid A is toxic component 3. Heat stable 5. Toxoids cannot be produced 6. Many effects on host 7. Produced by gram-negative organisms only
Enterobacter species
Isolated from wounds, urine, blood and CSF Major characteristics
Klebsiella
MR negative; VP positive
Enterobacter are gram-negative bacteria Found in the environment,on human skin, and in our intestinal tract. many are harmless,several species are opportunistic pathogens present in hospital settings. The most common pathogenic species are E. cloacae and E. aerogenes
The urinary and respiratory tracts are the most common sites of enterobacter infection. The lower respiratory tract, Urinary tract, Joint, Skin, Heart, Intra-abdomen, Soft tissue, Bone
Risk factor
Patients are most susceptible to enterobacter infections stay in the hospital, especially the ICU, for extended periods. Patients under the age of 2 and over the age of 65 Prior use of antimicrobial agents. Underlying diseases. Ulcers of the upper gastrointestinal tract. Presence of intravenous catheters. Serious conditions such as burns or mechanical ventilation.
Immunosuppression.
spread through contact with the bacteria on patients, contaminated surfaces, and medical equipment
Enterobacter cloacae infections are seen commonly in burn victims, immunocompromised patients, and patients with malignancy The urinary and pulmonary systems are the organ systems most commonly colonized in these patients.
Enterobacter sakazakii meningitis and death associated with powdered infant formula
Clinical Characteristics
Pathogenic organism
Case Description
Male patient admitted to neonatal intensive care unit (NICU) April 2001
gestational age 33.5 weeks, C-section delivery
grams
Case Description
Treated with ampicillin and cefotaxime Infant pulseless, resuscitated on pressors day 20: expired after withdrawal of support due to severe neurologic disease
Identification (contd)
All enterics are Oxidase negative Ferment glucose Reduce nitrates to nitrites
red Voges-Proskauer
Enterobacter species