A patient presents with dysuria and fever. Microscopy of the urine shows bacilli with a thin peptidoglycan layer and an outer membrane containing lipopolysaccharide. What Gram-stain result is expected?

A. Robert Koch: Robert Koch was a pioneering microbiologist known for establishing the germ theory of disease and developing Koch’s postulates to link specific microbes to specific diseases. He did not develop the formal system of classifying and naming organisms.

B. Ignaz Semmelweis: Ignaz Semmelweis was a physician who introduced hand hygiene practices in obstetrics to reduce puerperal fever. His contributions focused on infection control rather than taxonomy or nomenclature.

C. Aristotle: Aristotle proposed an early system of classification based on observable characteristics and divided living organisms into plants and animals. However, his system lacked standardization and binomial nomenclature.

D. Carolus Linnaeus: Carolus Linnaeus developed the formal system of taxonomy using hierarchical classification (kingdom, class, order, genus, species) and introduced the binomial nomenclature system, giving each organism a two-part Latin name (genus and species). His system is the foundation of modern biological classification.

E. Louis Pasteur: Louis Pasteur is known for his work on pasteurization, fermentation, and disproving spontaneous generation. While he made major contributions to microbiology, he did not establish a formal naming or classification system for organisms.

Viroids are the smallest known infectious pathogens and are composed solely of a short strand of circular, single-stranded RNA that lacks a protein coat (capsid). Because they do not have this protective protein shell, they are described as "naked" RNA molecules. Unlike viruses, which can infect a wide range of organisms, viroids are known exclusively to infect higher plants, where they can cause significant agricultural damage by interfering with plant growth and development.