During the golden age of antibiotic discovery, many newantibiotics were isolated from the soil. Recent studies have foundthat soil bacteria are naturally resistant to most antibotics. Someof the soil bacteria may even use antibiotics as a nutrient source.Antibiotics must kill a broad spectrum of bacteria while beingabsorbed harmlessly by the body. Most antibiotics were developedbased on Ehrlich \"magic bullet\" paradigm which is suited to testingantibiotic efficacy in a lab. However, infections are more complexthan a pure culture on media in a petri plate. Antibioticresistance conjures up the pre-antibiotic era of medicine in theearly 20th century. The emergence of a plasmid mediated resistanceto carbopenems, a last-line drug against a variety of bacteria wasalarming to public health workers. Antibiotics may cause collateraldamage like a C. diff infection that leads to colitis.
5. Why is a bacterial infection that involves a biofilm harderto control with antibiotics than an infection which does notinvolve a biofilm?
6. Explain how taking antibiotics would cause the bacteriaClostridium difficle, which is part of the healthy colonmicrobiome, to become pathogenic?
7. How do bacteria resist antibiotics?
Bacteria also develop resistance to biocides. Traditionalcleaning methods for equipment may have limitations. For example,patients who recieve a bed used by a prior patient with a bacterialinfection are at an increased risk for being colonized and infectedby that same bacteria. In addition, bacteria in a healthcaresetting are exposed to disinfection which selects for the resistantmembers of that bacterial population. No-touch methods ofdisinfection, i.e. uv light or hydrogen peroxide vapor, ofequipment may be an improvement.https://www.ncbi.nlm.nih.gov/pubmed/29214175# (Links to an externalsite.)Links to an external site..
8. Are biofilms a concern when disinfecting equipment? Why?
During the Flint, MI water crises as levels of chlorine fell inthe drinking water cases of Legionnaires' disease increased.Legionnaires' disease is a water borne infectious disease caused byLegionella. One study reported that for every drop incholorine concentration of mg/L of river water the odds of areported case of Legionnaire's disease increased by 80%, thusestablishing not causation but association. Some argued thatLegionella is tolerant of chlorine, espceillay when itgrows in biofilms and that the temperature difference between lakeand river water accounts for the increase in Legionellainfections. The recommended level of chlorine to treat water fordrinking is 0.2-0.5 mg/L.
doi:10.1126/science.aat2210 Was Flint’s deadly Legionnaires’epidemic caused by low chlorine levels in the water supply? DavidShult (Links to an external site.)Links to an external site.z
Was Flint’s deadly Legionnaires’ epidemic caused by low chlorinelevels in the water supply?
9. What effect would increasing the concentration of chlorine to1.4 mg/L have had on the people who drink Flint water?
10. What happens to the water pipes when chlorine levels areincreased to control bacteria? Could these uninteded consequencesincrease bacterial growth?
