A doctor stands with stethoscope in this undated handout photo..
(photo credit: REUTERS)
About a third of all hospital blood culture samples rated “positive” for a pathogen are thrown out daily because they’re “contaminated” – but the “infection” is actually due to germs on the skin and not bacteria in the body that cause disease. Instead of trashing these compromised samples, doctors may be able to use the resistance profiles of skin bacteria identified by these tests to treat patients with antibiotics appropriate to their ailment, according to a team headed by Tel Aviv University researchers.
Dr. Gidi Stein and Dr. Danny Alon of TAU’s Sackler Faculty of Medicine and the Rabin Medical Center-Beilinson Campus’s internal medicine department and Prof. Lilach Hadany and Uri Obolski of TAU’s molecular biology department conducted a retrospective study on more than 2,500 patients. Their test results, published in the Journal of Antimicrobial Chemotherapy, demonstrate the unique diagnostic value of “erroneous” cultures. The study showed the immediate effects on both public health questions and the treatment of individuals whose blood samples have been contaminated.
The more resistant the bacteria on the skin, the higher the risk of the infecting bacteria being resistant to antibiotics, the researchers found.
“These results can certainly be used for on-site clinical decisions. Once a contaminated sample has been found to be highly resistant, it is likely that the blood-borne pathogens will have a similar resistance pattern.
Thus antibiotic treatment may be better targeted for the actual pathogens,” said Hadany.
In the study, the researchers processed the demographic information, hospital records, blood culture results and date of death of all patients at the Petah Tikva hospital who had positive blood cultures between 2009 and 2012. They found that out of 2,518 patients, 1,664 blood cultures drawn from 1,124 patients reflected the presence of a common skin contaminant, coagulase-negative Staphylococci (CoNS). High overall CoNS resistance predicted high overall resistance of the bacteria causing disease or infection. Most importantly perhaps, highly resistant CoNS isolates were found to be associated with higher short-term mortality.
The researchers hope their conclusions will cause clinicians to pause before discarding contaminated blood test results.
“Because we have found a direct correlation between resistance profiles of CoNS contaminants and those of the actual infecting bacteria isolated from the same patient, the results of these ‘junk’ samples can be used to predict patient mortality and correct empirical antibiotic therapy,” said Stein. “This should serve as an additional, non-invasive, diagnostic tool.”
According to the researchers, most hospital patients are treated at the outset with broad-spectrum antibiotics. Days later, after initial test results are known, doctors replace broad-spectrum antibiotics with more precise narrow-spectrum antibiotics, which treat the specific bacteria identified by the blood sample.
It is well known that narrow-spectrum antibiotics are better for the body because they target specific bacteria as opposed to an entire microenvironment. Moreover, broad-spectrum antibiotics might result in altered bacterial environments of the skin and gastrointestinal tract, promoting inflammation and the emergence of resistant pathogens.
“The high rate of inappropriate antibiotic use puts patients and the general public at risk,” said Hadany.
“Improved matching of the treatment to the needs of the patient might reduce antibiotic load and the emergence of resistance.”
EXERCISE IF YOU WANT TO PROTECT HEART
People who think that drinking wine will protect their hearts due to antioxidants may be disappointed if they don’t exercise as well. Wine protects against cardiovascular disease (CVD) only in people who carry out regular physical activity, according to researchers who reported their findings recently at a congress in the Czech Republic.
Prof. Milos Taborsky, head of the cardiology clinic at the Olomouc Hospital and lecture at Palacky University Medical School said: “This is the first randomized trial comparing the effects of red and white wine on markers of atherosclerosis in people at mild-to-moderate risk of CVD. We found that moderate wine drinking was protective only in people who exercised. Red and white wine produced the same results.”
Since the 1990s, there has been much evidence from retrospective studies that wine increases levels of HDL, the “good” cholesterol, but until now, there has been no long-term, prospective, randomized study comparing the effects of red and white wine on HDL cholesterol and other markers of atherosclerosis.
The study included 146 cardiac patients randomized to drink red or white wine in moderate amounts five times a week for a year and who kept detailed records of their habits.
The researchers found that there was no difference between HDL cholesterol levels at the beginning of the study compared to one year in either the red or white wine groups. LDL (“bad”) cholesterol was lower in both groups at one year, while total cholesterol was lower only in the red wine group.
“Our current study shows that the combination of moderate wine drinking plus regular exercise improves markers of atherosclerosis, suggesting that this combination is protective against cardiovascular disease,” he concluded.