Enterobacteriaceae I E Coli Klebsiella And Proteus Question And Answers

Enterobacteriaceae I E. Coli, Klebsiella, And Proteus

Question 1. Enumerate organisms causing UTI. Describe morphology, cultural characteristics and pathogenesis of E. coli infection.
Answer:

Urinary Tract Infection (UTI) is defined as a disease caused by microbial invasion of the genitourinary tract that extends from the renal cortex of the kidney to the urethral meatus.

Enumeration of Causative Organisms

“Importance of studying Enterobacteriaceae for microbiology students: Questions explained”

1. Bacterial agents:
   • E. coli
   • Proteus mirabilis
   • Klebsiella spp
   • Staphylococcus aureus
   • Staphylococcus saprophyticus
   • Staphylococcus epidermidis
   • Enterococci
   • Pseudomonas aeruginosa
   • Enterobacter spp.
   • Citrobacter spp.
   • Acinetobacter spp.
   • Salmonella spp.
   • Ureaplasma urealyticum
   • Anaerobes such as Bacteroides fragilis
2. Fungal agents:
   • Candida albicans
   • Cryptococcus neoformans
3. Morphology of E. coli
   • E. coli is a gram-negative bacillus
   • It measures 1-3 µ × 0.4 – 0.7 µ.
   • Most strains are motile by peritrichous flagella.
   • It possesses fibriae.
   • It is non-sporing and non-capsulated.
4. Cultural Characteristics
   • E. coli is an aerobe and facultative anaerobe.
   • It grows on an ordinary culture medium at an optimum temperature of 37 °C in 18–24 hours.
   • Colonies of some strains show beta-hemolysis on blood agar.
   • On MacConkey medium, colonies are pink due to lactose fermentation.
   • In general, colonies are circular, moist, smooth with the entire margin, and non-mucoid unlike colonies of Klebsiella which are mucoid.
   • In a liquid medium, growth occurs as uniform turbidity.

“Understanding E. coli, Klebsiella, and Proteus through FAQs: Q&A explained”

Pathogenesis E. coli forms a part of the normal intestinal flora of man and animal.

Read And Learn More: Microbiology Question And Answers

There are four major types of clinical syndromes, which are caused by E. coli, are as follows:

1. Urinary tract infection
2. Diarrhea and dysentery
3. Pyogenic infections, and
4. Septicemia.

1. Urinary tract infection:
   • E. coli is the most common organism responsible for urinary tract infections. E. coli that causes UTI often originates in the intestine of the patient.
   • The route of infection to reach the urinary tract is either the ascending route or the hematogenous route.
   • The ascending route is through fecal flora spreading to the perineum and from there they ascend into the bladder.
2. Diarrhea and Dysentery: E. coli causes diarrheal diseases, which are of five groups. They produce diarrhea with different pathogenic mechanisms.
   • Enteropathogenic E. coli (EPEC): They cause enteritis in infants, especially in tropical countries. EPEC adhere tightly to enterocytes in the small intestine, leading to inflammatory reactions and epithelial degenerative changes, i.e. disrupting the brush border of microvilli.
   • Enterotoxigenic E. coli: These are the strains that form a heat-labile enterotoxin or a heat-stable enterotoxin, or both. They are now known to be a major cause of diarrhea in children in developing countries and are the most important cause of traveler’s diarrhea.

“Role of fimbriae and capsules in Enterobacteriaceae pathogenesis: Questions answered”

1. • Enteroinvasive E. coli: Some strains of E. coli invade the intestinal epithelial cells as do dysentery bacilli and produce disease identical to Shigella dysentery. They are non-motile and non-lactose fermenters. Their invasiveness is determined by plasmid and code for outer membrane antigen known as a virulence marker
     antigen.
   • Enterohemorrhagic E. coli or verotoxigenic E. coli: These strains cause mild diarrhea, hemorrhagic colitis, and hemolytic uremic syndrome. It is most common in infants and young children but can occur in all ages. It is characterized by marked hemorrhage, but fever is not always present. Its action is mediated by verotoxin
     which act on vascular endothelial cells.
   • Enteroaggregative E. coli: They are so named because they appear aggregated in a stacked-brick formation. They cause diarrhea in developing countries. Their action is mediated by enteroaggregative Escherichia coli-heat-stable enterotoxin-1.
2. Pyogenic infections: E. coli may cause wound infection, peritonitis, cholecystitis, and neonatal meningitis. It is an important cause of neonatal meningitis.
3. Septicemia: E. coli is a very common cause of septicemia in many hospitals and leads to fever, hypotension, and disseminated intravascular coagulation (endotoxin shock). This condition usually occurs in debilitated patients and mortality is very high.

“Common challenges in understanding Enterobacteriaceae effectively: FAQs provided”

Question 2. Name lactose and non-lactose fermenting bacteria.
Answer:

Following are the lactose fermenting bacteria and non-lactose fermenting bacteria.

Lactose Fermenting Bacteria There are various species of bacteria that are considered lactose fermenting bacteria. These species include:

“Steps to explain Enterobacteriaceae species: E. coli vs Klebsiella vs Proteus: Q&A guide”

1. Fast lactose fermenters:
   • Klebsiella pneumonia
   • E. coli
   • Enterobacter cloacae
   • Shigella sonnies
   • Clostridium perfringens.
2. Slow lactose fermenters:
   • Serratia marcescens
   • Citrobacter
   • Vibrio cholarae.

“Factors influencing success with Enterobacteriaceae knowledge: Q&A”

Being lactose fermenting bacteria, they utilize lactose.

Non-Lactose Fermenting Bacteria

• There are various species of bacteria that are considered
  non-lactose fermenting bacteria.
• These species include Salmonella, proteus species, Pseudomonas aeruginosa, Yersinia, and Shigella.
• Being non-lactose fermenting bacteria, they cannot utilize lactose.