1997 Richard J. Duma/NFID Annual Press Conference and Symposium on Infectious Diseases
Please Choose a Presenter
» Daniel L. Engeljohn, Ph.D.: "USDA Perspective on Food Irradiation"
» Ruth A. Etzel, M.D., Ph.D.: "Acute Pulmonary Hemorrhage in Infants: The Role of Flooding and Toxigenic Molds"
» Joseph M. Madden, Ph.D.: "FDA Perspective on Food Irradiation"
» John E. McGowan, Jr., M.D.: "Antibiotic Use and Infection Control
Practices Linked to Emergence of Antimicrobial Resistance in Hospitals A Project ICARE Report"
» Michael T. Osterholm, Ph.D., M.P.H.: "Protecting America's Food Supply from Microbial Contamination: The Role of Irradiation"
» Benjamin Schwartz, M.D.: "Drug-Resistant Pneumococcus A Challenge to the Nation's Health"
USDA Perspective on Food Irradiation
By Daniel L. Engeljohn, Ph.D.
Since January 1986 when the Food Safety and Inspection Service (FSIS) issued the first of two rules allowing irradiation as a food safety measure, FSIS has been mindful of the limited use of this studied and proven technology. The 1986 approval for pork irradiation was intended to provide a low-cost alternative to the traditional Trichinella spiralis control methods (i.e, cooking, curing, freezing or testing). However, to date, virtually no irradiated pork has been commercially marketed in the United States. In September of 1992, the second approval was issued for the reduction in the level of food-borne pathogens (i.e., Yersinia, Campylobacter and Salmonella) on poultry. FSIS actually submitted one of the food additive petitions to the Food and Drug Administration (FDA) requesting approval of poultry irradiation. Soon after the FSIS poultry irradiation rule was issued, one establishment began irradiating poultry and distributing it to limited geographical destinations (i.e., Florida and Illinois). Currently there are seven irradiation facilities which have received approvals to irradiate poultry; only one of these establishments has pursued and obtained an approval to irradiate pork. The approved irradiation facilities are located in the East (New Jersey), the Southeast (Florida and North Carolina), and the Midwest (Illinois and Iowa).
Expanded use of irradiation to include red meat, especially ground beef, would certainly fit within current FSIS efforts to implement pathogen reduction initiatives through Hazard Analysis Critical Control Point (HACCP) systems. Irradiation, like any other antimicrobial treatment, could be identified as a critical control point to effectively reduce--or, in some cases, eliminate--causative agents for food-borne illness. The use of irradiation on red meat has not yet been approved by FDA.
FSIS has made significant progress in modifying its regulations to improve the safety of meat, poultry and egg products. FSIS also has maintained a commitment to ensure the accurate and full labeling of foods. Irradiated pork and poultry must carry a label which identifies that the product has been irradiated. FSIS recognizes that evenly weighted information about its regulations, especially those that are new or controversial, helps consumers make informed decisions about the meat, poultry and egg products they purchase. The FSIS Information Office, including the USDA meat and poultry hotline at (800) 535-4555, provides enormous educational benefits to the public.
FSIS is committed to making sure that the nation's meat, poultry and egg products are safe. As emerging pathogens come to light, or as existing pathogens resurface, FSIS will continue to evaluate its regulations to assure that technology capable of reducing and/or eliminating food-borne threats is not hindered. However, FSIS will continue to be sensitive to the consumer's right to have full and accurate labeling of food.
Return to the list of presenters.
Acute Pulmonary Hemorrhage in Infants: The Role of Flooding and Toxigenic Molds
By Ruth A. Etzel, M.D., Ph.D.
Pulmonary hemorrhage in infants is a life-threatening disease in which previously healthy babies suddenly cough up blood. Although some cases of pulmonary hemorrhage are caused by bacterial infections or immunologic or cardiovascular abnormalities, for many cases the cause is not known. A recent cluster of cases of this rare disease among infants in Cleveland gave us the opportunity to identify a previously unrecognized link between this disease and mycotoxins, potent toxins produced by molds.
This association was uncovered because an astute clinician in Cleveland noticed that he was seeing an unusually large number of babies with pulmonary hemorrhage. He asked CDC to help him determine why this was happening. There were several remarkable things about the babies. First, all the babies' homes were clustered within six miles of each other in a relatively poor area of eastern Cleveland. Also, five of the 10 babies had recurrences of their pulmonary bleeding after returning to their homes. Even more remarkable was the fact that the infants' blood showed an unusual finding: their red blood cells were being lysed. This led us to wonder if the infants might be exposed to a toxin in their homes.
An extensive study of the 10 babies with pulmonary hemorrhage and 30 healthy babies from the same neighborhoods revealed that one important difference between the two groups was that the babies with pulmonary hemorrhage lived in homes that had suffered water damage as a result of flooding or plumbing problems. The water damage promoted the growth of a variety of molds, including the toxigenic mold Stachybotrys atra. Because S. atra requires water-saturated cellulose-based materials for growth in buildings, it is considered uncommon in homes. This mold produces potent toxins which are known to cause gastrointestinal hemorrhage and hemolysis in farm animals who eat moldy grain. This is the first time that it has been associated with disease in infants.
This finding is important for two reasons. First, pulmonary hemorrhage among infants has a high mortality (about 10 to 15 percent) and this discovery raises the possibility that some of these deaths could be prevented. Recurrent pulmonary bleeding in infants after discharge from the hospital might be prevented by assuring that the infant does not return to a moldy environment. Secondly, a small proportion of deaths classified as sudden infant death syndrome (SIDS) may actually be due to acute pulmonary hemorrhage.
Return to the list of presenters.
FDA Perspective on Food Irradiation
By Joseph M. Madden, Ph.D.
Section 201(s) of the federal Food, Drug and Cosmetic (FDC) Act defines any source of radiation used for the treatment of food as a "food additive." Thus, if a radiation source was not used for the treatment of a food prior to January 1, 1958, it is subject to Section 409 of the FDC Act in that, "Any person may, with respect to any intended use of a food additive, file with the Secretary (Secretary of the Department of Health and Human Services) a petition proposing the issuance of a regulation prescribing the conditions under which such additive may be safely used." The Food and Drug Administration (FDA) reviews these petitions to determine the efficacy of the radiation source in eliminating microbial pathogens, eliminating arthropod pests from foods or inhibiting the growth and maturation of fresh foods. In addition, the FDA determines the effect the radiation source may have on the availability/alteration of nutrients traditionally found in the food and determines if any deleterious substances are formed in/on the food as a result of treatment with the radiation source.
The FDA has approved the following ionizing radiation sources for the treatment of food: gamma rays from sealed units of the radionuclides cobalt-60 or cesium-137; electrons generated from machine sources at energies not to exceed 10 million electron volts; and, X-rays generated from machine sources at energies not to exceed 5 million electron volts. Limitations on the use of ionizing radiation for the treatment of food are as follows: for the control of Trichinella spiralis in pork carcasses; for growth and maturation inhibition of fresh foods; for disinfestation of arthropod pests in foods; for microbial disinfection of dry or dehydrated enzyme preparations; for microbial disinfection of dry or dehydrated aromatic vegetable substances when used as ingredients in small amounts solely for flavoring or aroma; for control of food-borne pathogens in fresh or frozen, uncooked poultry products; and for the sterilization of frozen, packaged meats used solely in the National Aeronautics and Space Administration space flight programs.
The FDA has received a petition for the use of ionizing radiation for the treatment of raw, freshly chilled/refrigerated and prefrozen beef, pork, sheep and horse meat. The purpose of the treatment is to help control microbial pathogens such as Bacillus cereus, Clostridium perfringens, Escherichia coli O157:H7, members of the genera Salmonella and Shigella, Staphylococcus aureus, Listeria monocytogenes, Yersinia species and to inactivate infectious parasites such as Toxoplasma gondii. A concomitant benefit of this treatment is the extension of chilled/refrigerated edible market life by delaying the onset of spoilage through the reduction of levels of meat spoiling microorganisms. The FDA is currently reviewing data submitted in support of this petition.
Return to the list of presenters.
Antibiotic Use and Infection Control Practices Linked to Emergence of Antimicrobial Resistance in Hospitals A Project ICARE Report
By John E. McGowan, Jr., M.D.
Dramatic changes are occurring in resistance of bacteria and other organisms to antimicrobial agents. Previously, these changes usually were seen in the intensive care unit (ICU) as new organisms appeared with inherent resistance to currently available antimicrobials, or greater resistance was found in organisms previously present. Today, however, newly resistant organisms may appear at any location of the health system, and the distinction between hospital and community resistance is blurring. The current relative importance of each location is unclear as are underlying risk factors.
Project ICARE (Intensive Care Antimicrobial Resistance Epidemiology) is a cooperative project of the National Nosocomial Infection Surveillance (NNIS) system of the Centers for Disease Control and Prevention (CDC) and the Rollins School of Public Health of Emory University. The study measures antibiotic resistance and antibiotic use in a subset of hospitals that participate in the intensive care component of the NNIS system of CDC. Data being collected include:
- Overall resistance for selected target organism/drug combinations, stratified into ICU, non-ICU inpatient and outpatient settings;
- Overall antimicrobial use, stratified into ICU and non-ICU inpatient settings;
- Resistance mechanism and epidemiologic typing for selected organisms.
Phase one was a pilot study in eight NNIS hospitals (1995); phase two (the current one) continues the study in a population-based sample of 41 NNIS hospitals chosen to be representative of location, size, and type of hospital (teaching, etc.). Phase two is being funded in part by a unique consortium of sponsors Zeneca Pharmaceuticals, American Society of Health-System Pharmacists, National Foundation for Infectious Diseases, RhÏne-Poulenc Rorer, Roche Laboratories, Kimberly-Clark Corporation and the Bayer Corporation Pharmaceuticals Division. It is anticipated that phase three will focus on specific factors that influence the pattern, and phase four will concentrate on prevention and control.
Phase one (pilot phase) results showed a significant stepwise decrease in percentage of resistant organisms isolated from patients in the ICU, non-ICU inpatients, and outpatients. These results suggest that resources allocated to control antimicrobial resistance should continue to be focused in the hospital, particularly in the ICU. Study findings to date also indicate that antimicrobial use and resistance are usually, but not always, linked. This means that dealing with antimicrobial resistance will have to address several associated factors: antimicrobial use, infection control practices, community burden of resistance and possibly others as well. The implications of this finding for resource allocation in hospitals and healthcare systems will be discussed.
Return to the list of presenters.
Protecting America's Food Supply from Microbial Contamination: The Role of Irradiation
By Michael T. Osterholm, Ph.D., M.P.H.
During the past decade, there has been a dramatic change in the epidemiology of food-borne diseases throughout the world. Increasingly, food-borne diseases are being attributed to a wide variety of bacteria, parasites and viruses, many which were previously unrecognized. Today, the risk of food-borne disease depends on the type of food, its production source, how it is prepared and handled and the consumer's resistance to the infectious agent. As these factors rapidly change, the epidemiology of food-borne disease also necessarily changes.
Primary factors in the changing and increasing problem of food-borne diseases are the combination of changes in diet and the commercial sources for these new food products. For example, the increased demand for fresh fruits and vegetables as part of a heart-healthy diet has also produced changes in where those items are produced. Seasonally, more than 75 percent of fresh fruits and vegetables are harvested outside the United States, particularly in developing countries, and delivered within days to grocery stores and restaurants. These are the same fruits and vegetables that, when consumed in those developing countries, pose an increased risk of acquiring travelers' diarrhea. We have documented increased outbreaks that have taken on a truly global dimension. They involve numerous viral, bacterial and parasitic pathogens associated with the widespread distribution of fresh fruit and vegetable items. There is little that consumers can do to personally protect themselves from these problems since food and vegetable washing does not decrease the risk of infectious disease transmission.
In addition, we have recognized an increasing number of outbreaks and sporadic cases of Escherichia coli O157:H7 and Salmonella infections associated with red meat and poultry products. Many of these outbreaks have involved multiple states and represent primary contamination of these products during production and processing.
Numerous steps are being taken to reduce the risk of food-borne disease, including the implementation of hazard analysis critical control point (HACCP) systems. This approach involves examining every step in the process of production, processing and distribution of food with the goal of identifying those steps at which our food supply is particularly vulnerable. However, this approach will not reduce the risk of food-borne disease unless a specific "critical control point" is introduced into the food preparation process as close downstream to the consumer as possible. In particular, those infectious agents of which small numbers can still cause infection will continue to be a major problem. We believe that terminal pasteurization, including the use of irradiation, pulsed, high-intensity light, increased atmospheric pressure treatment or other such pathogen elimination methods, will be necessary on a wide-scale basis if we are to realize a safer food supply in the United States and throughout the world.
Return to the list of presenters.
Drug-Resistant Pneumococcus A Challenge to the Nation's Health
By Benjamin Schwartz, M.D.
During the past decade, antibiotic-resistant pneumococci have emerged and pose a major threat to the success of therapy for a range of infections caused by this common pathogen. Streptococcus pneumoniae (pneumococcus) is the leading cause of community-acquired bacterial pneumonia, bloodstream infections and ear infections (otitis media). It is also the second leading cause of meningitis in the United States. Serious pneumococcal infections occur most often among infants, persons 65 years of age and older and those immunocompromised by underlying medical illness or medications. Pneumococcal infections cause about 20,000 deaths annually among persons of all ages in the United States and over one million deaths among children worldwide.
In the mid-1980s, about five percent of pneumococcal infections were caused by organisms that had intermediate resistance to penicillin and virtually no strains were highly resistant. Now, nationwide, about 20 percent of strains have some resistance and about 10 percent have high level resistance to penicillin. In addition, many strains have become resistant to multiple antibiotics. Pneumococcal ear infections now may be caused by organisms that are not susceptible to any oral antibiotic agent making it necessary to treat this common childhood infection using injectable antibiotics. Some pneumococcal organisms are resistant to all antibiotics except vancomycin, and this "drug of last resort" now is recommended first-line therapy for children with meningitis.
There are several consequences to the spread of drug-resistant pneumococci. Death or long term sequelae may result from ineffective treatment of meningitis. Chronic or recurrent infections also may occur; for children with ear infections, this may result in hearing loss, developmental delay and the need for surgical drainage of chronic infection. Focal infections (e.g., ear or sinus infections) may spread to the bloodstream or central nervous system; in several areas as resistance has increased so too has the number of severe pneumococcal infections. As a result, health care costs have increased due to more expensive antibiotic therapy, excess and prolonged hospitalization and recurrent and complicated infection.
The spread of resistance among pneumococci--the most common and deadly bacterial agent worldwide--demands that we change medical practices that result in the spread of resistance. Resistance is promoted by the widespread use of antibiotics. By killing susceptible organisms, antibiotic therapy provides a selective advantage to resistant organisms facilitating their spread. In order to decrease, halt or reverse the spread of pneumococcal resistance, we must decrease the unnecessary use of antibiotic agents. In the United States, over 120 million courses of outpatient antibiotics are prescribed each year, about three-quarters of which are used to treat respiratory infections. In the past two decades, coincident with the emergence of resistance, we have witnessed an explosion in the diagnosis and treatment of such infections. For example, between 1975 and 1990, the number of ear infections diagnosed in physicians' offices increased by almost 150 percent, from 9.9 to 24.5 million. While antibiotic therapy is important to treat some types of respiratory infections, for the millions of infections caused by viruses, this therapy is of no benefit and only creates a risk to the patient and to society. Patient expectations and physician uncertainty with diagnosis are major reasons for antibiotic overuse. Controlling the spread of resistance requires that physicians and patients work together to limit antibiotic use to where it truly is needed. The paradigm must change from one where antibiotics are expected and prescribed "just to be safe," to one where the safest course of action is not providing an antibiotic unnecessarily. A national effort by CDC, health departments and professional societies is underway to promote more judicious antibiotic use. The success of this campaign is crucial if we are to preserve antibiotic effectiveness for pneumococcal and other bacterial infections.
