Infectious Diseases Plate Rounds 4-24-24.pptx

Infectious Diseases Plate Rounds 4-24-24.pptx

1. Plate Round Discussion 4/24/24 Case 1: Aggregatibacter aphrophilus Case 2: Mycobacterium Chelonae Case 3: Acute Knee periprosthetic joint infection-broad spectrum PCR= Strepococcus Pneumonia

2. Aggregatibacter aphrophilus Occur in the mouth and oropharynx of healthy individuals. Formerly: Haemophilus aphrophilus Opportunistic pathogen occasionally implicated in subacute endocarditis, brain abscesses, sinusitis, arthritis and osteomyelitis often caused by dental treatments that cause a break of the oral mucosal barrier and a temporary bactereamia .

3. Diagnostic Testing This gives an appearance of a "Morse code" of dots and dashes. occasional filamentous forms. They may occur singly, in pairs or in small (big) clumps and show the tendency to bipolar staining. Oxidase and Catalase negative X & V factor requirements- X factor= +/-, V factor= neg, hemolysis= neg Susceptibility= tested for beta lactamase activity

4. Mycobacterium chelonae considered to be environmental saprophytes which are widely distributed in nature  common clinical manifestations are skin, soft tissue, and bone infections often related to infected piercing wounds, contaminated tattoo inks, plastic surgery, or liposuction . 

5. Diagnostic Testing Straight or slightly curved Gram-positive rods. Do not stain well with Gram stain. Colonies show faintly staining, "ghost-like" beaded Gram-positive bacilli are often helpful in establishing a diagnosis of mycobacteria Kinyoun stain: Positive (acid-fast) Rapid grower. colonies are non-pigmented, rough and wrinkled Susceptibility regiment includes- tobramycin (for M. chelonae tobramycin is more active than amikacin) , clarithromycin, linezolid, imipenem, or clofazimine.

6. Glossary Filamentous forms- are those whose cells are not separated following cell division and so tend to grow in the form of 'filaments’, slender threadlike or fiber. Bipolar stain- staining pattern that colors only the two opposite poles of the microorganism in question, leaving the rest of the bacterium unstained or a lighter color, resembles a safety pin Acid-Fast- physical property that gives a bacterium the ability to resist decolorization by acids during staining procedures. This means that once the bacterium is stained, it cannot be decolorized using acids routinely used in the process.