Analysis of Salmonella enterica serotype Typhi pulsed-field gel electrophoresis patterns associated with international travel.

Typhoid fever is a significant cause of morbidity and mortality worldwide, causing an estimated 16 million cases and 600,000 deaths annually. Although overall rates of the disease have dramatically decreased in the United States, the number of travel-related infections has increased in recent decades. Drug resistance among Salmonella enterica serotype Typhi strains has emerged worldwide, making antimicrobial susceptibility testing an important function in public health laboratories. Pulsed-field gel electrophoresis (PFGE) subtyping of food-borne and waterborne pathogens has proven to be a valuable tool for the detection of outbreaks and laboratory-based surveillance. This retrospective study examined the distribution of PFGE patterns of S. enterica serotype Typhi isolates from patients with a history of international travel. Isolates were collected as part of a passive laboratory-based antimicrobial susceptibility surveillance study. Isolates were PFGE subtyped by using the restriction enzyme XbaI to restrict the total genomic DNA. Isolates indistinguishable with XbaI were further characterized using the restriction enzyme BlnI. A total of 139 isolates were typed, representing travel to 31 countries. Restriction fragment patterns consisted of 14 to 18 fragments ranging in size from 580 to 40 kbp. Seventy-nine unique PFGE patterns were generated using XbaI. Isolates from the same geographic region did not necessarily have similar PFGE patterns. Of the 139 isolates, 46 (33%) were resistant to more than one antimicrobial agent (multidrug resistant [MDR]). Twenty-seven (59%) of 46 MDR isolates had indistinguishable PFGE patterns with both XbaI and BlnI. It appears that MDR S. enterica serotype Typhi has emerged as a predominant clone in Southeast Asia and the Indian subcontinent.

Invasive Haemophilus influenzae disease in adults. A prospective, population-based surveillance. CDC Meningitis Surveillance Group.

OBJECTIVE: To define the incidence of and possible risk factors for invasive Haemophilus influenzae disease in adults. DESIGN: Prospective, population-based surveillance of hospital and referral bacteriology laboratories. SETTING: Metropolitan Atlanta, Georgia community. PATIENTS: All patients with H. influenzae isolated from normally sterile sites (blood, cerebrospinal fluid, joint, pleura) from 1 December 1988 through 31 May 1990. MEASUREMENTS: Isolates of H. influenzae were analyzed for serotype and biotype status, outer membrane proteins, lipooligosaccharide phenotypes, ribotyping patterns and beta-lactamase production. RESULTS: A total of 194 cases of invasive H. influenzae occurred (annual incidence of 5.6 cases/100,000 population), of which 47 (24%) were in adults 18 years old or older (annual incidence 1.7 cases/100,000 adults). Adults with invasive H. influenzae ranged from 18 to 96 years; 79% were women. Bacteremic pneumonia accounted for 70% of the adult cases. Other sources for invasive H. influenzae in adults were obstetric infections, epiglottitis, and tracheobronchitis; one patient had meningitis. Underlying conditions were noted in 92% of the patients. Chronic lung disease was the most common risk factor, but pregnancy (annual incidence, 4.9/100,000 pregnant women), HIV infection (annual incidence, 41/100,000 known HIV-infected adults), and malignancy were also important. Overall mortality was 28% in adults, and over half of pregnancy-related infections resulted in fetal death. Fifty percent of the 40 isolates available for testing were serotype b; 47.5%, nontypable; and 2.5%, serotype f. Sixteen of the 45 isolates (36%) were ampicillin-resistant. Based on biotypes, outer membrane protein profiles, lipooligosaccharide phenotypes, and ribotyping patterns, the type b isolates showed less heterogeneity than the nontypable isolates but were distinguishable from one another. CONCLUSIONS: Adult cases currently represent one quarter of all cases of invasive H. influenzae disease. Half of the reported adult cases were caused by type b H. influenzae, and the rate of ampicillin resistance in H. influenzae isolates from adults was higher than previously reported. Haemophilus influenzae is an important cause of bacteremia in compromised adults.

Visions for the future.

I have discussed, from my vantage point as a public health specialist, areas for emphasis in control and prevention of nosocomial infections. Surveillance is the key to all control and prevention programs. With the constraints of resources and increasing responsibilities, infection control personnel have to be innovative, inventive, and imaginative in their approach to surveillance. The principles of epidemiology may be overlooked in the rush to perform. Epidemiology is a valuable science; it is being applied to an increasing number of problems inherent to hospitals. The community and the hospital are closely related in regard to nosocomial infections. There is constant two-way traffic of both people and bugs that can be properly addressed through cooperative action. The international arena may not have a great impact on each of you, but collectively, APIC has much to offer to developing countries. We should support with actions those countries that are becoming concerned over nosocomial infections. Regardless of your own priorities, there will be new and significant challenges to all practitioners of infection control, challenges related to new and currently unidentified problems, and unfortunately, fewer resources with which to meet the challenges. I congratulate APIC, its officers, and members on all you have done to focus attention and intellect on the problem of nosocomial infections. A humble beginning has been extremely productive by all possible criteria, especially by imitation, which is "the highest form of praise."

The surveillance of infectious diseases.

Surveillance is the collection, collation, and analysis of data and the dissemination to those who need to know so that an action can result. This article describes the clinician's critical role in disease reporting and outlines the benefits of surveillance to clinical practice. Four commonly used systems of disease surveillance are notifiable disease reporting, laboratory-based surveillance, hospital-based surveillance, and population-based surveillance. We analyze the relative strengths and limitations of each of these systems and present current efforts to evaluate and improve surveillance activities.

Pontiac fever: isolation of the etiologic agent (Legionella pneumophilia) and demonstration of its mode of transmission.

Pontiac fever, a unique epidemiologic form of legionellosis, is characterized by a short (one- to two-day) incubation period and a self-limited grippe-like illness without pneumonia. In 1968, the first documented outbreak of this syndrome affected persons who had entered a health department building in Pontiac, Michigan. Epidemiologic analyses clearly implicated as airborne agent and suggested that evaporative condenser water aerosols being disseminated by a defective air conditioning system played a key role in the outbreak. Guinea pigs that were exposed in the building and to laboratory aerosols of evaporative condenser water developed bronchopneumonia. Legionella pneumophilia (serogroup 1) was isolated from the exposed guinea pigs' lungs. Paired acute and convalescent serum specimens from 37 patients were tested by the indirect fluorescent antibody technique using L. pneumophila serogroup 1 antigen, and 31 (84%) had rises in titer from less than 32 to greater than or equal to 64.

Nosocomial infection control: role of the hospital administrator.

The role of the hospital administrator regarding the implementation and maintenance of programs for the prevention and control of nosocomial infections in U.S. hospitals is discussed. Data obtained in the Study on the Efficacy of Nosocomial Infection Control provide the basis for describing the backgrounds, demographic characteristics, functions, and potential functions of this official as s/he interacts with members of the infection control committee and other hospital staff. The infection control program of a hospital must have the support of the hospital administrator to be effective.

Nosocomial infection control: an overview.

Nosocomial infections are one of the most important public health problems in the world today. Although a great deal of attention is being directed toward the control and prevention of these infections, old problems continue to occur and new problems are constantly arising. The approximately 5% rate of nosocomial infections among patients admitted to acute-care hospitals has a significant impact on patients morbidity and morality and on the financial concerns of the patient, hospital, and community. An effective, efficient, and sensitive surveillance program developed to meet the needs of the individual hospital is absolutely necessary to obtain data on nosocomial infections from which controls and prevention programs can be developed. At the same time, lessons can be learned from the experience of other hospitals. The nosocomial infection control and prevention program must be under the general direction of a representative, interested, effective infection control committee. One area of importance under the committee's responsibility is that of an appropriate isolation program practiced by all persons within the hospital.

Nosocomial surgical infections: incidence and cost.

The data reported in this article support the findings of Dr. Altemeier; that is, infections among surgical patients remain a serious problem today. Urinary tract infections account for approximately 40 per cent of nosocomial infections among surgical patients. Surgical wound and skin infections account for one third of the nosocomial infections among surgical patients. Rates for wound infections rise with age, with increased length of hospitalization before surgery, and with increased duration of surgery. They are higher for patients who have an infection at a distant site and for those who have the more hazardous surgical procedures as determined by risk categories. Gram-negative organisms are more prevalent than gram-positive organisms. A nosocomial surgical wound infection lengthens the hospitalization by an average of 7.4 days and raises the cost of hospitalization by more than 800 dollars. Further analysis of the data is necessary in order to identify the risk factors likely to be most helpful in determining which patients are at increased risk of acquiring a nosocomial infection. Only when these factors are identified can the most direct and effective contact and preventive measures be implemented.

Legionnaires' disease: description of an epidemic of pneumonia.

An explosive, common-source outbreak of pneumonia caused by a previously unrecognized bacterium affected primarily persons attending an American Legion convention in Philadelphia in July, 1976. Twenty-nine of 182 cases were fatal. Spread of the bacterium appeared to be air borne. The source of the bacterium was not found, but epidemiologic analysis suggested that exposure may have occurred in the lobby of the headquarters hotel or in the area immediately surrounding the hotel. Person-to-person spread seemed not to have occurred. Many hotel employees appeared to be immune, suggesting that the agent may have been present in the vicinity, perhaps intermittently, for two or more years.