Question

A 45-year-old homeless man who abuses alcohol presents to the emergency department with fever and cough of 4-day duration. The cough is productive with thick, bloody phlegm. He complains of pain in the right side of his chest with coughing or taking a deep breath. He denies any other medical history and says he cannot remember the last time he saw a doctor. He does not smoke cigarettes but says he drinks a pint of whiskey whenever he can get it, and denies drug use. His temperature is 38.9oC, pulse 105 BPM, and respiratory rate is 30/breaths/minute. The lung examination is notable for decreased breath sounds and crackles in the right, lower posterior field. His WBC count is elevated. Chest radiography reveals a dense right lower lobe infiltrate with evidence of pulmonary abscess. Sputum samples are collected for gram stain and culture. Questions 1. What does a "productive cough" mean. 2. What features on the physical exam are abnormal? 3. What does "crackles" in the lung mean? 4. What is an abscess? 5. On which media would you plate or inoculate to grow the suspected organism? 6. If the gram stain reveals >25 squamous epithelial cells/low power field what would you do? The gram stain revealed gram negative rods with numerous white blood cells. Large, very mucoid colonies were found on BA and MacKonkey plates. Pink colonies were seen on the MacKonkey plate 7. What is your preliminary diagnosis of the organism? 8. What does the pink in the colony on the MacKonkey plate signify? 9. What does a very mucoid colony reveal about an organism? 10. The patient was initially given ampicillin however the organism was resistant to ampicillin. What makes the organism resistant to ampicillin? What other antibiotic would be effective? The organism was found to be non-motile, MUG test, nitrate reduction, esculin hydrolysis positive and H2S negative. It also fermented the following sugars: maltose mannitol, mannose, glucose, and arabitol 11. What is your definitive diagnosis? 12. What family does this organism belong to? 13. How is motility tested? 14. This organism is also prevalent in hospital-acquired UTIs and respiratory infections. What is one underlying characteristic of patients who get infected with this organism? 15. Name another respiratory organism that is prevalent in the homeless population.

Answer 1

1.Productive cough means that it is not dry, on coughing mucous or phelgm comes out. The chest feels heavy due to production of mucous.

2. Productive cough, blood in phelgm, high body temperature, pulse rate and respiratory rates are high, swelling or inflamation on right side of the thoracic part due to infection can be seen when examined.

3. Due to mucous secretion or blocked air path the bronchioles produce a pop open sound when air is drawn in while inhalation, which is known as crackle in lungs.

4. Abscess is a bacterial infection caused by bacteria in which pus is produced. Due to accumulation of pus the area appears swelled.

5. Tryptic soy broth (TSB) and EZ medium are media used when organism is unknown. MacConkey agar for gram-negative bacteria. Mannitol salt agar is selective for Gram-positive bacteria

6. if gram stain reveals more than 25 squamous epithelial cells/ low power field than the person is likely to suffer from infection. The colonies resemble Klebsiella spp.: Mucoid lactose fermenter (MLF)

7. Bacteria belonging to the genus Klebsiella frequently cause human nosocomial infections. In particular, the medically most important Klebsiella species,Klebsiella pneumoniae, accounts for a significant proportion of  pneumonia, septicemias, and soft tissue infections.

8.Lactose-fermenting organisms grow as pink to brick red colonies with or without a zone of precipitated bile. Neutral red pH indicator present in the macConkey media which is red in color at pH’s below 6.8. When lactose is fermented, the pH of the medium decreases, changing the color of neutral red to pink

9. Strongly lactose fermenting bacteria produce sufficient acid which causes precipitation of the bile salts around the growth. It appears as a pink halo surrounding individual colonies or areas of confluent growth. Pink halo in not seen around the colonies of weaker lactose fermenting bacteria. Due to ppt of bile mucoid colonies are seen

10. Klebsiella possesses beta-lactamase giving it resistance to ampicillin. Ertapenem/meropenem can be effective.

11.