Clinical Bacteriology: Non-Spore-Forming, Non-Branching, Catalase-Negative Gram-Positive Rods

Flashcards covering the characteristics, clinical significance, and laboratory identification of Erysipelothrix, Arcanobacterium, Gardnerella, Lactobacillus, Truepella, and Weisella.

Rudimentary branching

A characteristic where a chain of bacilli appears to have branches at a specific point; observed in some catalase-negative, non-spore-forming, gram-positive rods.

Erysipelothrix rhusiopathiae

The most pathogenic member of its genus for humans; it is associated with occupation-related exposures like fish vendors, butchers, and veterinarians.

Vaginosis

A polymicrobial infection resulting from a superinfection that reduces normal flora, distinguished from vaginitis which is a monomicrobial inflammation.

Arcanobacterium haemolyticum

A species that mimics S. pyogenes in colonial characteristics and disease manifestation, often recovered in pharyngitis cases with scarlatiniform rash.

Erysipeloid

A localized skin infection also known as Fish-handlers Disease or Rosenbach Disease, characterized by purplish-red, elevated lesions on the hands.

Bacterial Vaginosis (BV)

A polymicrobial infection involving G. vaginalis, characterized by a malodorous fishy odor and a vaginal pH greater than $4.5$.

Clue cells

Large squamous epithelial cells with a sunny side appearance, covered in numerous short rods (G. vaginalis), also referred to as Dirty Cells in urinalysis.

H2S production

The hallmark biochemical positive result used to identify Erysipelothrix rhusiopathiae.

Test tube brush

The characteristic growth pattern manifested by Erysipelothrix rhusiopathiae in gelatin medium at $22\,^{\circ}C$.

Reverse CAMP test

A biochemical test where Arcanobacterium haemolyticum produces arrow head hemolysis when streaked perpendicular to S. aureus or S. agalactiae.

Colistin-Nalidixic Acid Agar (CNA)

A medium containing $5\%$ sheep's blood and antibiotics used to prevent the growth of gram-negative bacteria while supporting fastidious gram-positives.

Human Blood Bilayer Tween Agar (HBT)

A selective CNA-based medium with an overlay of blood and amphotericin B used specifically to recover Gardnerella vaginalis.

Tomato Juice Agar

The cultivation medium used specifically for the isolation of Lactobacillus spp.

Weisella confusa

An organism isolated in cases of bacteremia and endocarditis that is distinguished from Lactobacillus by being vancomycin-resistant.

Sodium polyanethol sulfonate (SPS)

A component in blood culture medium that inhibits the growth of Gardnerella vaginalis.

Truepella pyogenes

A species genetically related to Arcanobacterium that is identified as gelatinase positive.

Lactobacillus acidophilus

A member of the normal vaginal microbiota that maintains an acidic environment by releasing lactic acid.

Metronidazole

An antiprotozoal agent typically used to treat G. vaginalis infections due to the synergistic relationship of the organism with protozoans and yeast.

E. rhusiopathiae rough colonies

Colonies characterized microscopically as slender filamentous rods that tend to over-decolorize, appearing gram-variable or gram-negative.

Hippurate Hydrolysis

A biochemical test for which Gardnerella vaginalis yields a positive result.