Alice Goodman
September 13, 2010 (Boston, Massachusetts) — Perianal swabs failed to detect 1 in 5 cases of multidrug-resistant Gram-negative (MDRGN) bacteria in hospitalized patients with a newly identified MDRGN culture.
Researchers were not able to identify patient factors or types of care that could predict failure of the swab to identify MDRGN bacteria in this study, which was conducted in hospitalized patients known to be infected with MDRGN bacteria. The results were presented here at the 50th Interscience Conference on Antimicrobial Agents and Chemotherapy. A reliable method of detecting MDRGN bacteria in infected but asymptomatic patients has the potential to prevent the spread of MDRGN infection, the authors pointed out.
"We used these swabs in patients who were positive for MDRGN bacteria and we anticipated that we would detect MDRGN bacteria in 100%. Our study suggests that the ability to detect MDRGN bacteria among the generalized hospitalized population may be limited," said lead author Graham M. Snyder, MD, a fellow at Beth Israel Deaconess Hospital in Boston, Massachusetts. Erika D'Agata, MD, and Lara Venkataraman, PhD, also from Beth Israel Deaconess Hospital, were coauthors.
"Future research should be aimed at more accurate methods of surveillance than the swab used in our study and investigate whether there are groups of patients for whom the swab may be more accurate," Dr. Snyder added.
This study used standard agar plates infiltrated with ciprofloxacin or ceftazidime to screen for MDRGN bacteria. Other methods include PCR-based tests for carbapenemase-producing organisms and CHROMagar, he said. Perianal swabs were used because they are easy to perform and more comfortable than full rectal swabs, Dr. Snyder said. In addition to the rectum, potential sites for swabs include the groin, stool, wound, and perineum.
Thirty-five patients agreed to participate in the study, 3 of whom harbored 2 different species of MDRNG bacteria, for a total of 38 distinct MDRNG-patient pairs. The surveillance swab correctly identified 30 of the 38 (78.9%) MDRGN bacteria from clinical isolates. The perianal skin swab identified 1 or both MDRNG clinical isolates in 29 (82.9%) of the 35 patients.
Dr. Snyder gave some potential explanations for the findings. "Failure to detect 20% of MDRNG bacteria could be related to a time lag between identification of the organism initially and using a perianal swab. Or perhaps other sites were colonized and we didn't use a swab on those sites. It is also possible that our methods [microbiological plates] may not have been sensitive enough," he suggested.
"In the big picture, we need to carefully consider the methods we use for active surveillance. We need to think about the site of the swab and the methods we use," Dr. Snyder told Medscape Medical News.
More Optimistic View of Study
"I was impressed by the sensitivity of Dr. Snyder's method, which was around 80% in this study. The study consisted of patients already on antibiotics, which would theoretically have decreased the sensitivity of surveillance swabs to detect the organisms," said Mary-Claire Roghmann, MD, from the University of Maryland in Baltimore.
Dr. Roghmann told Medscape Medical News that she thought that the method of perianal swab testing could have higher sensitivity if performed prior to treatment with antibiotics, as occurred in this study.
"Based on this study, I actually think that the use of perianal swabs is promising," she stated.
Dr. Snyder and Dr. Roghmann have disclosed no relevant financial relationships.
50th Interscience Conference on Antimicrobial Agents and Chemotherapy (ICAAC): Abstract K-317. Presented September 12, 2010.
jueves, 23 de septiembre de 2010
NDM-1 Gene Spreading to Multiple Bacteria Species, Making Them Antibiotic-Resistant
Alice Goodman
September 22, 2010 (Boston, Massachusetts) — The gene that encodes for New Delhi metallo-beta-lactamase-1 (NDM-1), which confers resistance to most currently available antibiotics, appears to be spreading from the Indian subcontinent (India, Pakistan, and Bangladesh), researchers reported here at a media press conference during the 50th Interscience Conference on Antimicrobial Agents and Chemotherapy (ICAAC).
NDM-1 has recently been documented in strains of bacteria in Australia, France, Japan, Kenya, North America, Singapore, Taiwan, and the United Kingdom. The emergence of this gene poses the threat of a pandemic with few treatment choices, said researchers.
In 2 separate reports at ICAAC, investigators described cases of NDM-1 in Escherichia coli in Canada and in Klebsiella sp. in Australia, prompting the news conference. Both case reports involved patients who had recently traveled to India. No one really knows the true prevalence of NDM-1-infiltrated bacteria, the researchers said, but they believe that the spread from India to other parts of the world is at least partly due to a confluence of a large Indian diaspora returning to their homeland for visits and to the phenomenon of medical tourism to India.
"The reservoir is in India, Pakistan, and Bangladesh, and is due to factors that are not controllable — overuse of antibiotics, poor hygiene, and diarrhea in an overcrowded overpopulated country. A plague could spread around the world, first through the Indian diaspora, which constitutes 20 million people all over the world," warned Patrice Nordmann, MD, from the Hôpital de Bicêtre, Le Kremlin-Bicêtre, France. "We feel it's only a question of time." Dr. Nordmann was a panelist at the press conference.
It is not known how widespread NDM-1 is in India, "which is one of our greatest concerns," added Timothy Walsh, MD, from Cardiff University in the United Kingdom.
"Our data are not accurate, but there are billions of people in India without clean water and sanitation. Massive antibiotic usage and antibiotics in the sewage create a nightmare that is a perfect recipe. Selective pressure fuels antibiotic resistance, and bugs are put on hyperdrive to accept DNA with NDM-1 encoded in plasmids," Dr. Walsh said.
Since the abstracts describing the 2 case reports of NMD-1-associated resistance were submitted to the ICAAC, other cases have emerged in Australia and Canada. Culture of the infection in Canada revealed the same strains of NMD-1 E coli identified in the United Kingdom and India. In the Australian case, NDM-1 was present in Klebsiella pneumoniae isolated from a foot wound.
"Both patients in Canada were treated successfully, but according to lab tests, only 3 antibioticswere found to have any effect — tigecycline, colistin, and phosphomycin," said senior author of that abstract, Johann Pitout, MD, from the University of Calgary in Alberta.
Perhaps more important is the fact that general practitioners are not used to seeing multidrug resistance associated with NDM-1, and if this type of infection does become common, infected patients may not get appropriate treatment, Dr. Pitout stated. "General practitioners are not qualified to treat these infections," he asserted.
September 22, 2010 (Boston, Massachusetts) — The gene that encodes for New Delhi metallo-beta-lactamase-1 (NDM-1), which confers resistance to most currently available antibiotics, appears to be spreading from the Indian subcontinent (India, Pakistan, and Bangladesh), researchers reported here at a media press conference during the 50th Interscience Conference on Antimicrobial Agents and Chemotherapy (ICAAC).
NDM-1 has recently been documented in strains of bacteria in Australia, France, Japan, Kenya, North America, Singapore, Taiwan, and the United Kingdom. The emergence of this gene poses the threat of a pandemic with few treatment choices, said researchers.
In 2 separate reports at ICAAC, investigators described cases of NDM-1 in Escherichia coli in Canada and in Klebsiella sp. in Australia, prompting the news conference. Both case reports involved patients who had recently traveled to India. No one really knows the true prevalence of NDM-1-infiltrated bacteria, the researchers said, but they believe that the spread from India to other parts of the world is at least partly due to a confluence of a large Indian diaspora returning to their homeland for visits and to the phenomenon of medical tourism to India.
"The reservoir is in India, Pakistan, and Bangladesh, and is due to factors that are not controllable — overuse of antibiotics, poor hygiene, and diarrhea in an overcrowded overpopulated country. A plague could spread around the world, first through the Indian diaspora, which constitutes 20 million people all over the world," warned Patrice Nordmann, MD, from the Hôpital de Bicêtre, Le Kremlin-Bicêtre, France. "We feel it's only a question of time." Dr. Nordmann was a panelist at the press conference.
It is not known how widespread NDM-1 is in India, "which is one of our greatest concerns," added Timothy Walsh, MD, from Cardiff University in the United Kingdom.
"Our data are not accurate, but there are billions of people in India without clean water and sanitation. Massive antibiotic usage and antibiotics in the sewage create a nightmare that is a perfect recipe. Selective pressure fuels antibiotic resistance, and bugs are put on hyperdrive to accept DNA with NDM-1 encoded in plasmids," Dr. Walsh said.
Since the abstracts describing the 2 case reports of NMD-1-associated resistance were submitted to the ICAAC, other cases have emerged in Australia and Canada. Culture of the infection in Canada revealed the same strains of NMD-1 E coli identified in the United Kingdom and India. In the Australian case, NDM-1 was present in Klebsiella pneumoniae isolated from a foot wound.
"Both patients in Canada were treated successfully, but according to lab tests, only 3 antibioticswere found to have any effect — tigecycline, colistin, and phosphomycin," said senior author of that abstract, Johann Pitout, MD, from the University of Calgary in Alberta.
Perhaps more important is the fact that general practitioners are not used to seeing multidrug resistance associated with NDM-1, and if this type of infection does become common, infected patients may not get appropriate treatment, Dr. Pitout stated. "General practitioners are not qualified to treat these infections," he asserted.
Antibiotic Prescribing Habits Have Shifted According to Pathogen Prevalence Patterns
Alice Goodman
September 22, 2010 (Boston, Massachusetts) — The choice of which antibiotic to prescribe as initial empiric therapy for hospitalized patients with complicated skin and skin-structure infections has changed substantially over the past decade, suggesting that physicians are responding to an increase in methicillin-resistant Staphylococcus aureus (MRSA), Pseudomonas aeruginosa, and Gram-negative infections in general. Multidrug use is also much more common than it was 10 years ago, according to a retrospective study reported here at the 50th Interscience Conference on Antimicrobial Agents and Chemotherapy.
The use of vancomycin — the most widely used drug for MRSA — increased dramatically, whereas the use of cefazolin and ampicillin/sulbactam — 2 drugs used to treat methicillin-susceptible S aureus — declined over the same period. Concomitantly, a marked increase was seen in prescribing pipericillin/tazobactam, a broad-spectrum antibiotic covering Gram-negative infections.
"These changes in initial antibiotic therapy in hospitalized patients undoubtedly reflect increasing concern about pathogen resistance and changes in treatment guidelines. Our objective was to see whether physicians are responding to the changing environment in infectious disease, and our study suggests that they are," said senior author David Weber, MD, professor of medicine, pediatrics, and epidemiology at the University of North Carolina in Chapel Hill.
The study used the Cerner Health Facts electronic database to identify 22,832 adult patients hospitalized for complicated skin and skin-structure infections in the United States between 2000 and 2009; 75% were hospitalized for acute infections, 18.3% for infections at the surgical site, and 6.6% for chronic infections.
A marked decrease over time was observed in the use of cefazolin (from 22.1% to 6.9%) and ampicillin/sulbactam (from 19.9% to 6.0%), whereas the use of vancomycin increased 4-fold (from 5.6% to 22.6%), and the use of piperacillin/tazobactam plus vancomycin increased more than 10-fold (from 0.9% to 12.9%. Piperacillin/tazobactam monotherapy increased more than 2-fold (from 2.8% to 6.5%).
Dr. Weber pointed out that the use of vancomycin as either a single agent or as part of a multidrug regimen increased from 16.5% in 2000 to 55.4% in 2009. During that time period, the use of piperacillin/tazobactam either as a single agent or as part of a multidrug regimen increased from 6.8% to 20.9%.
Over the same time period, the use of initial regimens providing coverage for P aeruginosa increased from 16.4% to 28.1%, and antibiotic regimens providing broad-spectrum coverage for Gram-negative infections increased from 22.1% to 36.1%.
Dr. Weber cited several limitations of this study: its retrospective design, the fact that its database might not be generalizable to all American hospitals, and the fact that it provided no information on why initial antibiotics were selected.
Commenting on this study, Vance Fowler, MD, associate professor at Duke University in Durham, North Carolina, said: "Multidrug-resistant pathogens are on the rise in critically ill patients who present to the hospital with life-threatening complications of skin and skin-structure infections. We want to make sure we are choosing antibiotics wisely."
"Physicians have to make an educated guess during the first 24 hours of hospitalization, and they get points for being right. You know antimicrobial resistance is climbing in the hospital setting, and your job is to ensure that the patient in the bed right now has the best chance to get the best therapy out of the gate," he continued.
"This study implies physicians are doing their job," Dr. Fowler stated.
Dr. Weber reports receiving financial support from Policy Analysis Inc and the Forest Research Institute of New York City. Dr. Fowler reports financial ties with Astellas, Cubist, Merck, Theravance, Pfizer, Novartis, Inhibitex, Arpida, Targanta, Wyeth, Ortho-McNeil, Vertex Pharmaceuticals, Leo Pharmaceuticals, NovaDigm, The Medicines Company, Baxter Pharmaceuticals, Biosynexus, and Johnson & Johnson.
50th Interscience Conference on Antimicrobial Agents and Chemotherapy (ICAAC): Abstract L1-1761. Presented September 14, 2010.
September 22, 2010 (Boston, Massachusetts) — The choice of which antibiotic to prescribe as initial empiric therapy for hospitalized patients with complicated skin and skin-structure infections has changed substantially over the past decade, suggesting that physicians are responding to an increase in methicillin-resistant Staphylococcus aureus (MRSA), Pseudomonas aeruginosa, and Gram-negative infections in general. Multidrug use is also much more common than it was 10 years ago, according to a retrospective study reported here at the 50th Interscience Conference on Antimicrobial Agents and Chemotherapy.
The use of vancomycin — the most widely used drug for MRSA — increased dramatically, whereas the use of cefazolin and ampicillin/sulbactam — 2 drugs used to treat methicillin-susceptible S aureus — declined over the same period. Concomitantly, a marked increase was seen in prescribing pipericillin/tazobactam, a broad-spectrum antibiotic covering Gram-negative infections.
"These changes in initial antibiotic therapy in hospitalized patients undoubtedly reflect increasing concern about pathogen resistance and changes in treatment guidelines. Our objective was to see whether physicians are responding to the changing environment in infectious disease, and our study suggests that they are," said senior author David Weber, MD, professor of medicine, pediatrics, and epidemiology at the University of North Carolina in Chapel Hill.
The study used the Cerner Health Facts electronic database to identify 22,832 adult patients hospitalized for complicated skin and skin-structure infections in the United States between 2000 and 2009; 75% were hospitalized for acute infections, 18.3% for infections at the surgical site, and 6.6% for chronic infections.
A marked decrease over time was observed in the use of cefazolin (from 22.1% to 6.9%) and ampicillin/sulbactam (from 19.9% to 6.0%), whereas the use of vancomycin increased 4-fold (from 5.6% to 22.6%), and the use of piperacillin/tazobactam plus vancomycin increased more than 10-fold (from 0.9% to 12.9%. Piperacillin/tazobactam monotherapy increased more than 2-fold (from 2.8% to 6.5%).
Dr. Weber pointed out that the use of vancomycin as either a single agent or as part of a multidrug regimen increased from 16.5% in 2000 to 55.4% in 2009. During that time period, the use of piperacillin/tazobactam either as a single agent or as part of a multidrug regimen increased from 6.8% to 20.9%.
Over the same time period, the use of initial regimens providing coverage for P aeruginosa increased from 16.4% to 28.1%, and antibiotic regimens providing broad-spectrum coverage for Gram-negative infections increased from 22.1% to 36.1%.
Dr. Weber cited several limitations of this study: its retrospective design, the fact that its database might not be generalizable to all American hospitals, and the fact that it provided no information on why initial antibiotics were selected.
Commenting on this study, Vance Fowler, MD, associate professor at Duke University in Durham, North Carolina, said: "Multidrug-resistant pathogens are on the rise in critically ill patients who present to the hospital with life-threatening complications of skin and skin-structure infections. We want to make sure we are choosing antibiotics wisely."
"Physicians have to make an educated guess during the first 24 hours of hospitalization, and they get points for being right. You know antimicrobial resistance is climbing in the hospital setting, and your job is to ensure that the patient in the bed right now has the best chance to get the best therapy out of the gate," he continued.
"This study implies physicians are doing their job," Dr. Fowler stated.
Dr. Weber reports receiving financial support from Policy Analysis Inc and the Forest Research Institute of New York City. Dr. Fowler reports financial ties with Astellas, Cubist, Merck, Theravance, Pfizer, Novartis, Inhibitex, Arpida, Targanta, Wyeth, Ortho-McNeil, Vertex Pharmaceuticals, Leo Pharmaceuticals, NovaDigm, The Medicines Company, Baxter Pharmaceuticals, Biosynexus, and Johnson & Johnson.
50th Interscience Conference on Antimicrobial Agents and Chemotherapy (ICAAC): Abstract L1-1761. Presented September 14, 2010.
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