Question

need help with 7-9 questions

A 48 y/o man had a long history of alcoholism (including alcoholic hepatitis and hallucinosis) and was admitted to the intensive care unit with profound hypotension and gastrointestinal bleeding. He was intubated and given intravenous fluids and transfused with packed red blood cells. He remained intubated and ventilator dependent for several weeks. He developed fevers and was treated with broad-spectrum antibiotics. Culture of his tracheal aspirate initially showed Staphylococcus aureus. After further antibiotic therapy, Gram stain of his tracheal aspirate showed polymorphonuclear leukocytes and gram negative rods. His chest radiograph demonstrated an infiltrate and changes consistent with multiple small abscesses. Culture of the tracheal aspirate yielded a heavy growth of an oxidase positive, beta-hemolytic, nonlactose-fermenting, gram negative rod that produced a greenish hue on the culture plates. 1. What is the likely agent of infection? 2. is this organism part of the normal oral microbiota? No i s Not No 3. Where is it found in the hospital environment? 4. Does it commonly cause pulmonary infections in healthy individuals? 5. This organism produces an exotoxin that is similar to the exotoxin of which other bacterium? 6. Which pigments does this organism produce? 7. This organism was isolated after the patient received a prolonged course of broad-spectrum antibiotics. What role did antibiotics play in the etiology of this infection? Bacterial genes may code for a variety of proteins that inactivate antibiotics via a variety of mechanisms. Give one example of this phenomenon. In addition to the bacterial chromosome, where else can genes which code for resistance factors be found? Give an example of this phenomenon. 8. 9.

Answer 1

7.Antibiotics(against a living microorganisms -bacteria) are killed.Most of them kills the bacterial cell walls,some inhibit the protein synthesis.Penicillin are a group of antibiotics used for several infections . For example beta lactic group inhibits cell wall formation, Macrolides inhibit or kill ribosomes necessary for protein production of bacteria. Quinolones break the formation of similar DNA of the host by bacteria, The action of the medication administered belongs to penicillin group and thereby the bacterial virulence  are killed and leading to relief of the symptoms.

8.When an antibiotics does not relieve symptoms it is called as antibiotic resistance. This happens mainly by some mechanisms like

• The bacteria getting a new DNA sequence from the previously existing bacteria
• Genetic mutations happening in the ribosome if the bacteria making the antibiotics not to identify its strain

E.g.,Tetracycline antibiotics once available to treat a variety ,the bacteria has developed resistance to it.It undergoes a gene mutation (DNA strands are changed or altered),and the bacteria will produce a ribosome in it that can protect the protein of the bacteria. So when tetracycline are administered they are not able to recognize the bacteria due to the new code.

8.Bacterial chromosomes are one which are altered during resistance development.In addition to it binds to conjugative plasmids.They can evem float in the cytoplasm called nucleiod.

E.g..Amoxicillin are resistant to broad spectrum antibiotics .E Coli resistant to amoxicillin and chloramphenicol.