TIPSHEET
Highlights from the Journals of the American Society for Microbiology
December 1997
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SIMPLER, LESS EXPENSIVE TEST FOR ULCER BUG
Researchers from the University of Wurzburg in Germany have determined that a simple antibody test may be as effective in detecting Helicobacter pylori infection as the more invasive procedures that are currently used. They report their findings in the December 1997 issue of the Journal of Clinical Microbiology.
In the study, the researchers compared the sensitivity of a test for H. pylori-specific antibodies from a class known as immunoglobulin G (IgG) with the standard tests in clinical practice. The antibody test had a 98 percent sensitivity, correctly diagnosing 58 of the 59 patients diagnosed by standard methods.
"The current gold standard tests in clinical practice, endoscopy for histology and the rapid urease test, are limited by their relatively high costs and the need for invasive procedures," say the researchers. "Determination of antibodies against H. pylori presents a relatively simple diagnostic method, with kits that can be used to perform this method now being readily available from commercial sources."
H. pylori is a bacterium that lives in the harsh acidic environment of the stomach. It is the cause of most duodenal ulcers and an estimated 70-80 percent of gastric ulcers and is considered a risk factor for stomach cancer.
(S. Karvar, H. Karch, M. Frosch, W. Burghardt, and U. Gross. 1997. Use of serum-specific immunoglobulins A and G for detection of Helicobacter pylori infection in patients with chronic gastritis by immunoblot analysis. Journal of Clinical Microbiology. 35:3058-3061.)
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NATURAL ANTIBIOTIC RESISTANCE
Some bacteria in the environment may already have a natural resistance to certain antibiotics, due to only to genetic variation and not antibiotic exposure, and could provide a key to rational design of new antibiotics, say researchers in the December 1997 issue of the journal Antimicrobial Agents and Chemotherapy.
The researchers, from TerraGen Diversity, Inc., in Vancouver, Canada, studied random samples of bacteria cultured from soil, looking at their resistance to the family of antibiotics known as flouroquinolones and the genetic basis for their natural resistance. They found that the quinolone-resistance determining region of the bacterial gene known as gyrA was highly variable and that flouroquinolone-resistance was due in part to natural DNA sequence variation.
"Sequence analysis of microbes that are naturally resistant to potential antimicrobials would be valuable in predicting mechanisms of resistance likely to be encountered in subsequent clinical use," say the researchers. "Such early warning would permit rational design of agents active against resistant strains."
(B. Waters and J. Davies. 1997. Amino acid variation in the GyrA subunit of bacteria potentially associated with natural resistance to fluoroquinolone antibiotics. Antimicrobial Agents and Chemotherapy. 41: 2766-2769.)
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PINE-BASED CLEANERS MAY CONTRIBUTE TO ANTIBIOTIC RESISTANCE
Repeated exposure to household cleaners containing pine oil may cause bacteria to develop resistance to some common antibiotics, say researchers from Tufts University School of Medicine in the December 1997 issue of the journal Antimicrobial Agents and Chemotherapy.
In the study the researchers repeatedly exposed the bacteria Escherichia coli to a household cleaner containing the disinfectant pine oil or pure pine oil itself in order to isolate pine-oil resistant strains. The resistant strains were then tested against a variety of antibiotics. All pine oil-resistant strains were also multidrug resistant.
"To our knowledge, the selection of chromosomal antibiotic resistance, albeit low level, by a disinfectant has not previously been reported for gram-negative bacteria," say the researchers. "Whether pine oil in products meant for household use could lead to a significant problem of antibiotic resistance is not know. However, it seems possible that additional disinfectants might be capable of selecting for resistance to antibiotics and vice versa."
(M.Moken, L.M. McMurry and S. Levy. 1997. Selection of multiple-antibiotic-resistant mutants of Escherichia coli by using the disinfectant pine oil: roles of the mar and acrAB loci. Antimicrobial Agents and Chemotherapy. 41:2770-2772.)
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