Microbiology

Baltimore classification organizes viruses into 7 groups based on replication strategy and genetic material type, applicable to both bacterial and eukaryotic viruses.

Streptococcus pneumoniae is distinguished by optochin sensitivity (alpha-hemolytic) and bile solubility, with lancet-shaped cocci causing bacterial meningitis.

Reverse transcriptase converts retroviral ssRNA into dsDNA, a critical step unique to retroviruses before integration into the host chromosome via integrase.

Proteus mirabilis produces urease, alkalinizing urine and promoting precipitation of magnesium ammonium phosphate (struvite), forming characteristic staghorn calculi.

ESBL-producing Gram-negative bacteria (E. coli, Klebsiella) hydrolyze third-generation cephalosporins, conferring resistance to multiple beta-lactam antibiotics.

Coronaviruses are characterized by crown-like spike proteins (S protein) on their enveloped surface, which are distinctive under electron microscopy.

Negative-sense RNA viruses (-ssRNA) cannot be directly translated; they require RNA-dependent RNA polymerase to synthesize complementary positive-sense mRNA first.

Antigenic drift (point mutations) and antigenic shift (reassortment of gene segments) allow influenza to escape previously acquired immunity, making vaccination necessary annually.

Pseudomonas aeruginosa is a non-fermentative, oxidase-positive, Gram-negative rod commonly associated with respiratory infections and shows characteristic green pigmentation.

Haemophilus species are fastidious gram-negative coccobacilli requiring both X factor (hemin) and V factor (NAD). Culture on chocolate agar provides these factors; they won't grow on regular blood agar.