Tips from Interscience Conference on Antimicrobial Agents, Chemotherapy

Johns Hopkins researchers report potentially life-threatening hospital infections with bacteria resistant to the antibiotic methicillin can occur even if patients havent been treated with that drug. But, they add, these infections can be stopped with one of medicines oldest and most powerful antibacterial treatments: hand washing.

We know theres more to MRSA infection than just exposure to antibiotics, says infection control and antibiotic management expert Xiaoyan Song, MD, MS, a research associate at Hopkins. So the best way to avoid these infections is for doctors and nurses to wash their hands before they touch you, and for patients to tell their caregivers to wash their hands before they touch you.

Song led a look-back study of 2,279 patients admitted to Hopkins between 2000 and 2002. None of the patients had a history of methicillin-resistant Staphylococcus aureus (MRSA) infection, after hospital stays averaging 19 days, but 3.4 percent (77) patients acquired the infection anyway.

Compared to patients who remained MRSA-free at discharge, MRSA patients tended to have additional medical problems, such as chronic respiratory illness and/or liver or kidney disease. In addition, patients infected with MRSA were also more likely to be admitted to an intensive care unit or a medical ward, or to have been transferred from other health care facilities. The Hopkins researchers suspect that unclean hands among health care workers were the likely cause.

The Hopkins team discovered that there was no exclusive or clear association in their patient population between those given antibiotics and those who acquire S. aureus bacteria resistant to methicillin. MRSA infections can cause serious pneumonia or surgical wound infections, says Song.

Although patients infected with MRSA were up to 2.6 times more likely to have been treated with an antibiotic such as carbapenem or vancomycin, the researchers found that antibiotic treatment alone was not a risk factor for acquiring this organism.

Prior Antibiotic (ABX) Exposure Is Not Associated with Methicillin-Resistant Staphlococcus aureus (MRSA). Xiaoyan Song, Sara Cosgrove, Trish Perl


New Quick Test for Drug-resistant Strains of Gonorrhea

Potential antimicrobial resistance in the bacteria that cause gonorrhea can be detected without culturing the organism, thanks to a rapid test developed by researchers at Johns Hopkins.

Key to the usefulness of the new test is that it does not require collection, culture or testing of the bacteria themselves -- called Neisseria gonorrhea. Instead, the genes linked to resistance can be identified in urine samples or in leftover products from other commonly used diagnostic techniques, the Hopkins team reports.

This new application of probe technology should help public health officials study the spread of antibiotic-resistant gonorrhea by simplifying analysis of samples that cannot be used for culturing organisms, the Hopkins group added.

The Hopkins team developed the test by using an existing diagnostic technology called nucleic acid amplification tests (NAATs). These are FDA-approved tests that detect gonorrhea DNA in urine samples. Using leftover DNA from NAATs, the team performed a polymerase chain reaction (PCR) to make copies of genes linked to resistance. They then performed a melt curve analysis to detect mutations in these areas. In melt curve analysis, a short DNA sequence that matches the bacterial sequence in question is labeled with a fluorescent dye. The labeled sequence, called a probe, emits light only when bound to its target.

The probe and the DNA copies produced by PCR are dissolved together and the solution is slowly heated and cooled. This lets the probe bind to its target. Then the solution is slowly heated until the probe is melted from its target. A special instrument measures the temperature at which the probe melts from the DNA by identifying the temperature at which the probe ceases to emit light. The probe melts at a lower temperature if the target contains mutations and at a higher temperature if there are no mutations in that region of the gene. As a result, the lower melt temperature indicates potential resistance.

Rapid detection and characterization of gonococcal resistance determinants in NAAT samples. Julie Giles, Justin Hardick, Jeffrey Yuenger, Charlotte Gaydos, Jonathan Zenilman.


Comprehensive, Online Guide Assists Clinicians in the Diagnosis, Management and Treatment of HIV/AIDS
The Johns Hopkins Point of Care Information Technology (POC-IT) Center launched a clinical decision support tool for HIV disease (The Johns Hopkins HIV Guide, at ICAAC on Oct. 30.

The field of HIV/AIDS care changes rapidly, making it difficult for physicians to keep up to date with the new information while investing the time needed to actually care for patients, notes the guides editor in chief, infectious disease specialist Joel Gallant, MD, MPH, an associate professor of medicine and epidemiology at Hopkins. The HIV Guide addresses that dilemma by enlisting the help of a team of AIDS experts to break down new information into very easily accessible, cross-referenced modules that cover all aspects of HIV/AIDS care.

Gallant will lead a group of more than 35 nationally recognized experts in HIV/AIDS care, who will produce and update the guides database on new treatments and practices.

The HIV Guide will include an HIV resistance tool that will help clinicians manage patients failing therapy by providing individualized interpretations of patients genotypic resistance test results. This key tool will help health care providers avoid prescribing drugs that would have limited effectiveness because of resistance mutations, according to Gallant.

The guides panel of experts will closely monitor and digest information in the fields of diagnostic testing, drugs, infectious pathogens associated with immune deficiency, and HIV disease management, according to Paul Auwaerter, MD, MBA, chief medical officer of Johns Hopkins POC-IT and associate professor of medicine at Hopkins.

The authors not only update their own modules regularly, but also list the references linking users to the original papers through PubMed, says Auwaerter. This service allows the user to go right to original source materials for more information. PubMed is a service of the National Library of Medicine that links users to millions of abstracted and full text articles.

The HIV Guide, based on the Johns Hopkins Point of Care Information Technology (POC-IT), joins a growing family of Web-based clinical guides, according to Gallant. Although not yet formatted for downloading onto personal digital assistants (PDA), the AIDS guide will eventually join POC-ITs flagship product, the Johns Hopkins Antibiotic Guide (ABX Guide, as both a Web- and PDA-based database.

The ABX Guide has been widely accepted by the medical community. The April 2003 issue of Clinical Infectious Diseases singled it out as the best infectious disease point-of-care tool available. In addition, it was called a must have by Pharmacy Practice News.

Future POC-IT guides are expected to cover other specialties, eventually encompassing most of the fundamental knowledge sought by physicians, whether as part of daily ambulatory practice, performing emergency care, or for continuing medical education.

POC-IT technologys bidirectional data flow means that as the guide pushes new information into PDAs synchronized to the Web site, there is an automatic, reverse flow of information from the registered PDA or Web site audience regarding their use of the guide. This information represents a database that informs researchers how clinicians around the country are treating specific diseases. Such information will be invaluable in helping clinical and health care policy researchers assess medical practices around the country, says Gallant.

The two-way communication should also facilitate communication among clinicians seeking assistance from their colleagues in recruiting patients for clinical trials of new treatments, Auwaerter says.

Source: Johns Hopkins Medical Institutions