Insufficient antibiotics available for cystic fibrosis patients: Study

Turns out, the majority of patients with cystic fibrosis may not achieve blood concentrations of antibiotics sufficiently high enough to effectively fight bacteria responsible for pulmonary exacerbations, thus leading to worsening pulmonary function.

Cystic fibrosis, a genetic condition that affects about 70,000 people worldwide, is characterised by a buildup of thick, sticky mucus in patients’ lungs. There, the mucus traps bacteria, causing patients to develop frequent lung infections that progressively damage these vital organs and impair patients’ ability to breathe.

A recent study led by researchers at Children’s National Health System shows that it’s impossible to predict solely from dosing regimens which patients will achieve therapeutically meaningful antibiotic concentrations in their blood. The findings were published online in the Journal of Pediatric Pharmacology and Therapeutics.

These infections, which cause a host of symptoms collectively known as pulmonary exacerbations, are typically treated with a combination of at least two antibiotics with unique mechanisms. One of these drugs is typically a Beta-lactam antibiotic, a member of a family of antibiotics that includes penicillin derivatives, cephalosporins, monobactams and carbapenems.

Although all antibiotics have a minimum concentration threshold necessary to treat infections, Beta-lactam antibiotics are time-dependent in their bactericidal activity. Their concentrations must exceed a minimum inhibitory concentration for a certain period. However, study’s lead author Andrea Hahn explained that blood concentrations of Beta-lactam antibiotics aren’t typically tracked while patients receive them.

Since antibiotic dosing often doesn’t correlate with cystic fibrosis patients’ clinical outcomes, Dr. Hahn and other researchers examined whether patients actually achieved serum antibiotic concentrations that are therapeutically effective.

In addition, all the patients underwent pulmonary function tests at the start of their exacerbations and about once weekly until their antibiotic therapy ended.

Using the data points, the researchers constructed a model to determine which patients had achieved therapeutic concentrations for the bacteria found in their respiratory secretions. They then correlated these findings with the results of patients’ pulmonary function tests. Just 47 per cent of patients had achieved therapeutic concentrations. Those who achieved significantly high antibiotic exposure had more improvement on their pulmonary function tests compared with patients who didn’t.

Paradoxically, they discovered that although each patient received recommended antibiotic doses, some patients had adequately high serum antibiotic concentrations while others did not.

Another way to ensure patients receive therapeutically meaningful levels of antibiotics is to develop new models that incorporate variables such as age, gender, and creatinine clearance–a measure of kidney function that can be a valuable predictor of metabolism–to predict drug pharmacokinetics.

Using findings from this research, Dr. Hahn adds, Children’s National already has implemented an algorithm using different variables to determine antibiotic dosing for patients treated at the hospital.

Original article here.

Triclosan, often maligned, may have a good side — treating cystic fibrosis infections

By Chris Waters

Maybe you’ve had the experience of wading in a stream and struggling to keep your balance on the slick rocks, or forgetting to brush your teeth in the morning and feeling a slimy coating in your mouth. These are examples of bacterial biofilms that are found anywhere a surface is exposed to bacteria in a moist environment.

Besides leading to falls in streams or creating unhealthy teeth, biofilms can cause large problems when they infect people. Biofilms, multicellular communities of bacteria that can grow on a surface encased in their own self-produced matrix of slime, can block immune cells from engulfing and killing the bacteria or prevent antibodies from binding to their surface.

On top of this, bacteria in a biofilm resist being killed by antibiotics due to the sticky nature of the matrix and activation of inherent resistant mechanisms, such as slow-growing cells or the ability to pump antibiotics out of the cell.

Biofilms are one of the primary growth modes of bacteria, but all antibiotics currently used clinically were developed against free-swimming planktonic bacteria. This is why they do not work well against biofilms.

My laboratory studies how and why bacteria make biofilms, and we develop new therapeutics to target them. Because antibiotic resistance is the most problematic aspect of biofilms during infections, we set out to identify novel molecules that could enhance antibiotic activity against these communities.

We discovered that an antimicrobial that has recently obtained a bad reputation for overuse in many household products could be the secret sauce to kill biofilms.

The hunt for antibiotic superchargers

To find such compounds, we developed an assay to grow plates of 384 tiny biofilms of the bacterium Pseudomonas aeruginosa. We did this to screen for molecules that enhance killing by the antibiotic tobramycin. We chose this bacterium and this antibiotic as our test subjects because they are commonly associated with cystic fibrosis lung infections and treatment.

People with cystic fibrosis (CF) are at particular risk from biofilm-based infections. These infections often become chronic in the lungs of cystic fibrosis patients and are often never cleared, even with aggressive antibiotic therapy.

After we screened 6,080 small molecules in the presence of tobramycin, we found multiple compounds that showed the antibiotic enhancement activity we were searching for. Of particular interest was the antimicrobial triclosan because it has been widely used in household products like toothpaste, soaps and hand sanitizers for decades, indicating that it had potential to be safely used in CF patients. Triclosan has also garnered a bad reputation due to its overuse, and states like Minnesota have banned it from these products. The Food and Drug Administration banned its use from hand soaps in September 2016. This ruling was not based on safety concerns, but rather because the companies that made these products did not demonstrate higher microbial killing when triclosan was added, compared to the base products alone.

Another fact that piqued our interest is that P. aeruginosa is resistant to triclosan. Indeed, treatment with either tobramycin or triclosan alone had very little activity against P. aeruginosa biofilms, but we found that the combination was 100 times more active, killing over 99 percent of the bacteria.

We further studied this combination and found that it worked against P. aeruginosa and other bacterial species that had been isolated from the lungs of CF patients. The combination also significantly enhanced the speed of killing so that at two hours of treatment, virtually all of the biofilm is eradicated.

Our efforts are now focused on pre-clinical development of the tobramycin-triclosan combination. For CF, we envision patients will inhale these antimicrobials as a combination therapy, but it could also be used for other applications such as diabetic non-healing wounds.

Although questions about the safety of triclosan have emerged in the mainstream media, there are actually dozens of studies, including in humans, concluding that it is well tolerated, summarized in this extensive EU report from 2009. My laboratory completely agrees that triclosan has been significantly overused, and it should be reserved to combat life-threatening infections.

The next steps for development are to initiate safety, efficacy and pharmacological studies. And thus far, our own studies indicate that triclosan is well tolerated when directly administered to the lungs. We hope that in the near future we will have enough data to initiate clinical trials with the FDA to test the activity of this combination in people afflicted with biofilm-based infections.

We think our approach of enhancing biofilm activity with the addition of novel compounds will increase the usefulness of currently used antibiotics. Learning about how these compounds work will also shed light on how bacterial biofilms resist antibiotic therapy.

Original article here.

OWN IT: MCR-1 is Here

So… there have been some pretty big news headlines the past few days. Between gorillas, a kid calling the police to report his dad going through a RED LIGHT and the Florida Panthers appeasing their fan base of 15 with new logos and jerseys, last week was pretty crazy. Continue reading OWN IT: MCR-1 is Here