What are the common organisms classified as gram-negative bacilli?

The group of organisms identified as gram-negative bacilli includes a variety of pathogens commonly associated with infections. Escherichia coli, Klebsiella, and Pseudomonas are well-known gram-negative bacilli that play significant roles in both community-acquired and healthcare-associated infections.

Escherichia coli is a major cause of urinary tract infections and can also lead to gastrointestinal diseases. Klebsiella species are associated with pneumonia and bloodstream infections, particularly in individuals with weakened immune systems. Pseudomonas aeruginosa is notorious for its resistance to multiple antibiotics and is often implicated in infections related to cystic fibrosis, burns, and indwelling devices.

In contrast, the other options listed do not belong to the gram-negative bacilli category. Staphylococcus and Streptococcus are gram-positive cocci, while Mycobacterium tuberculosis is classified as an acid-fast bacillus, and Bacillus cereus is gram-positive as well. Understanding the classification of bacteria based on their gram-staining characteristics is crucial for proper identification and treatment choices in a clinical setting.