Screening for respiratory syncytial virus and assignment to a cohort at admission to reduce nosocomial transmission Keith Krasinski, MD, Rita L a C o u t u r e , RN, Robert S, Holzman, MD, Evans W a i t h e , MS, S t a n l e y Bonk, Bs, a n d Bruce Hanna, PhD From the Departments of Pediatrics, Nursing, Medicine, and Pathology, New York University Medical Center-Bellevue Hospital Center, New York, New York To limit nosocomial spread of respiratory syncytical virus (RSV) infection, a longitudinal intervention trial was instituted. Nasal secretions or washes were screened for RSV antigen by enzyme-linked immunosorbent assay, and patients were assigned to an RSV-infected or an RSV-uninfected cohort. The baseline (preintervention) rate of 7.17 nosocomial cases of RSV per 1000 patient-days of care was used for comparison. Despite continued infections in the community after screening was initiated, t h e r e were no cases of RSV infection in 1880 patient-days of care for 3 months (p = 0.039). During the fourth month, an RSVinfected child was erroneously assigned to the RSV-uninfected cohort, and three nosocomial cases occurred--5.33/1000 patient-days of c a r e (p = 0.286). Overall, there were three nosocomial RSV infections in 2443 patient-days of care in the 1987 season after screening was introduced--1.23/1000 patient-days of care (p = 0.026). In the subsequent RSV season, there was one nosocomial case m 0.461/1000 patient-days of care for 3 months (p = 0.0074). During the same period, nosocomial cases of RSV were observed in the pediatric and neonatal intensive care units, where assignment to a cohort was not possible. We c o n c l u d e that entry into a cohort at the time of admission, on the basis of prospective RSV screening by enzyme-linked immunosorbent assay, e f f e c t i v e l y reduces nosoc o m i a l transmission of RSV. (J PEDIATR1990;116:894-8)
Respiratory syncytial virus is a major cause of morbidity and contributes to the death of infants and children, 1-3 especially premature infants, children with cardiac malformations, and immun0compromised patients. 47 In the decade of the 1980s, inner city hospitals are serving an increasing population of children infected with human immunodeficiency virus who may have a life-threatening Presented at the 28th Interscience Conference on Antimicrobial Agents and Chemotherapy, Los Angeles, Calif., Oct. 25, 1988. Submitted for publication Aug. 10, 1989; accepted Dec. 6, 1989. Reprint requests: Keith Krasinski, MD, Department of Pediatrics, New York UniVersity Medical Center, 550 First Ave., New York, NY 10016. 9/20/18665
illness caused by RSV. 8 This virus can spread readily among hospitalized patients and staff, with attendant morbidity and burden on hospital resources. 9, 10 Efforts to control the spread of infection have led to the use of glove-and-gown ELISA RSV
Enzyme-linked immunosorbent assay Respiratory syncytial virus
infection control precautions, to interrupt the spread of viruses by direct contact with droplets, fomites, and self-inoculation. Studies have demonstrated conflicting results about the efficacy of these measures.ll~4 The introduction of novel eye-nose goggles to prevent self-inoculation has also been associated with a reduction in the acquisition of RSV infection by staff. 15
Volume 116 Number 6
Control o f nosocornial R S V
BACKGROUND In September 1985, Bellevue Hospital Center replaced category-specific isolation practices with disease-specific infection control precautions, as suggested in guidelines published by the Centers for Disease Control) 6 These guidelines recommend a private room and the use of gowns, when soiling is likely, for the hospital care of RSV-infected infants and young children. They also suggest that assignment to cohorts is appropriate during epidemics. The use of masks and gloves is not recommended. During the first month of the 1986-1987 seasonal outbreak of RSV at Bellevue, there were four severe nosocomial cases of RSV infection in a ward accommodating children younger than 3 years of age; these resulted in the institution of additional measures to attempt to limit the spread of RSV among hospitalized patients. The purpose of this study was to determine the efficacy of those measures.
250 2OO n "b
0 Jan-87 May-87 Sep-87 Jan-88 Mar-87 Jul-87 Nov-87 Mar-88
Figure. Total number of pediatric hospital admissions and number of RSV-infectedchildren per month betweenJanuary 1987 and April 1988. Hatched portion of bars indicates infected children; solid portion of bars indicates noninfected children.
METHODS Children who were 3 years of age and older were admitted to a pediatric ward that is equipped with private rooms for the control of communicable diseases. These rooms are also used for younger infants and children who require a private room for infection control. Children younger than 3 years of age were admitted to a separate ward without private rooms, where as many as four children shared a room. All pediatric patients hospitalized on or before Dec. 31, 1986, were regarded as potentially infected with RSV and were constituted as an RSV-infected cohort; the group was divided by age as is customary. A second cohort, free of infection with RSV, was established on the toddlers' ward to segregate high-risk patients (defined as those younger than 3 years of age and those with congenital heart disease, chronic pulmonary disease, or an immunosuppressive disorder) from RSV-infected patients. The RSV-infected cohort was housed in ward rooms that are on the same corridor but that are physically separated, by 100 feet of intervening administrative offices, from the uninfected high-risk cohort. Visitation restrictions were instituted, and inpatient elective surgery was postponed for pediatric patients defined as being at high risk for severe RSV infection as defined above. Patients requiring hospital admission and assignment to the high-risk cohort were screened for evidence of RSV infection by means of a rapid ELISA method. Nasal secretions or nasal washes with saline solution were collected in a DeLee trap, transported to the laboratory, and tested. During the RSV epidemic period, RSV testiiag was immediately available around the clock. Testing was accomplished with an ELISA for direct RS y antigen (Pathfinder, from Kallestad Diagnostic Inc., Chaska, Minn.) according to the manufacturer's instructions. Results were usually
available within 2 hours of the time of presentation with illness in the clinic or emergency department. Virus cultures were not routinely grown. Children awaiting outpatient examination were placed in a waiting room in the clinic or pediatric emergency department before assignment to an examination room. After the need for admission was establilshed, samples were obtained for RSV testing. While awaiting placement in the appropriate cohort, children stayed in the clinic or emergency examination room in which they had been seen. Children at high risk who were found not to harbor RSV were assigned to the "clean" cohort. Children who were at high risk but were already infected with RSV were assigned to the other cohort. Decisions regarding ribavirin treatment were dictated by the clinical condition of the patient and were made individually by the house staff. Gowns were used for patient contact when soiling was likely. No gloves or masks were used in the RSV cohort. Infection control memoranda, in:service education programs for house staff and nursing staff, and routinely scheduled rounds and conferences were used to emphasize the risks and means of RSV transmission and the appropriate control measures. The RSV ELISA test became available in December 1986. Surveillance for community-acquired RSV infection was accomplished by review of the microbiology laboratory records. Surveillance for nosocomial infection, including RSV, was conducted as usual, with charge nurses of individual units actively identifying all children with infection syndromes and supplying a written list to the infection control staff on a weekly basis. Hospitalized patients with new onset of symptoms had additional specimens collected for RSV antigen determination. Infections were considered
K r a s i n s k i et al.
The Journal o f Pediatrics June 1990
T a b l e . Effect of screening and cohort assignments on nosocomial respiratory syncycial virus infections
Nosocomial RSV cases
Infant-toddler ward Nov-Dec 1986; before screening program Jan-Mar 1987; during screening program April 1987; after assignment of RSV infected patient to uninfected cohort, despite screening Jan-April 1987; season total with screening program May-August 1987; nonepidemic period, no screening program Sept 1987 to April 1988; season total with screening program Intensive care units Pediatric unit Jan-April 1987 Sept 1987 to April 1988 Neonatal unit Jan-April 1987 Sept 1987 to April 1988
Patient.days of care
Rate per 1000 patient-days
4 0 3
558 1880 563
7.17 0 5.33
--* 0.397 0.286
*Baselinerate for statisticalcomparisons.
nosocomial if onset occurred more than 4 days after hospital admission. The diagnoses of pediatric patients discharged between July 1, 1986, and June 30, 1989, selected by computer review of medical records data for diagnoses coded as lower respiratory tract infections (International Classification of Diseases, ninth edition, Clinical Modification: diagnosis codes 464.1, 466.1, 480.1, 480.8, 480.9, and 486), were compared monthly during the 3-year period of observation. Infection rates were statistically compared by means of the binomial distribution to calculate exact probabilities of obtaining the observed frequencies of infection. RESULTS Before and during December 1986, screening for RSV was not performed, and no prevalence data are available On the frequency of RSV infection among admitted children. However, RSV infection was documented in seven children receiving care on the ward for younger children during December, because of the recent availability of rapid testing. Nosocomial acquisition was identified in four patients (7.17 nosocomial infections per 1000 patient-days of care). Despite continued RSV activity in the community from January to March 1987 (Figure), no case of nosocomial RSV infection occurred in 1880 patient-days of care. In April 1987, a child with community-acquired RSV was erroneously admitted to the RSV-free cohort. This child was recognized as belonging to the high-risk group, and his nasal specimen was positive for RSV; the test results
were returned to the emergency department. Nevertheless, the child was placed in the RSV-free cohort. This exposure resulted in three nosocomial cases (5.33 nosocomial cases of RSV per 1000 patient-days of care) (Table). During the entire first season of screening, there were three nosocomial cases of RSV infection in 2443 patient-days of care (1.23/ 1000 patient-days of care). Screening was discontinued during four nonepidemic spring and summer months (May to August 1987). During this period there was one nosocomial case of RSV infection (0.404/1000 patient-days of care). The routine screening and assignment to a cohort of patients admitted to the ward for infants and young children were reinstituted in September 1987. Despite hospital admission of children with RSV during the 1987-1988 season, only one nosocomial case of RSV infection was observed (0.461/1000 patient-days of care) on that ward. To determine whether the observed reduction of nosocomial RSV infections was due to reduced community activity of RSV, we reviewed the proportion of patients admitted with RSV and the incidence of lower respiratory tract disease based on discharge diagnoses. During each of the winter seasons of 1986-1987 and 1987-1988, the proportion of screened patients who were infected with RSV was 0.29% for comparable periods from January to the end of March. The proportion of pediatric patients with the same discharge diagnoses of lower respiratory tract infection was 13.8%, 18.3%, and 12.8% for November and December 1987 and January 1988, and 8.3%, 13.4%, and 15.7% for
Volume 116 Number 6
November and December 1988 and January 1989, respectively. Therefore thereduction could not be explained by the reduction of RSV activity in the community. Assignment of patients and staff to cohorts was not possible in the pediatric intensive care unit or the neonatal intensive care unit because of the severity of patient illnesses, availability of beds for the care of infants and children with the most severe illness, and shortages of professional staff. Nosocomial acquisition of RSV was observed in these areas during both the 1986-1987 and 1987-1988 seasonal outbreaks, including five cases in the pediatric intensive care unit (3.6/1000 patient-days of care) and seven cases in the neonatal intensive care unit (1.8/1000 patient-days of care). DISCUSSION Despite published reports regarding the frequency and potential severity of nosocomial transmission of RSV among infants and children, and despite studies that detail methods of reduction in transmission rates, nosocomial transmission continues to occur and is likely related to several factors. Failure to co~ply with standard hand-washing procedures for routine patient care would be expected to make a major contribution to the spread of RSV. 17 The use of gloves, goggles, and protective equipment to prevent patient inoculation and autoinoculation would probably be unnecessary if hospital staff would rigorously apply handwashing principles to their routine patient care activities. Another possible contributing factor may be the perception among (adult) nurses and physicians that upper respiratory tract infections ("colds") are merely annoyances that will not cause harm if transmitted. However, RSV infection may be life threatening in high-risk groups. In addition, the press of clinical practice, and the opportunity for transmission created by the admission of many RSV-infected children with respiratory symptoms during epidemic winter months, interact to enhance the nosocomial spread of RSV. The seasonal occurrence of RSV in the community is heralded by an increase in children admitted to hospitals with acute lower respiratory tract disease. 2 These children constitute a large source of RSV for nosocomial transmission. The possibility that an unusually large number of patients admitted with community-acquired RSV contributed to the high rate of nosocomial infections in December 1986 is unlikely. On the basis of a review of medical records data for the 1986-1988 period, the proportion of children with nonbacterial acute lower respiratory tract i nfection and the number of pediatric patients who received care on the same services were comparable. Indeed, the proportion of admitted children with lower respiratory infection increased from 12.9% in December 1986, when the index nosocomial cases occurred, to 15.2% in January 1987; however, the rate of nosocomial infection decreased.
Control o f nosocomial R S V
The introduction of rapid, easily performed viral diagnostic techniques has created the opportunity to examine the effect of another intervention to prevent nosocomial transmission. Our data show that the assignment of patients to an appropriate cohort on the basis of prospective screening for the presence or absence of RSV in nasal secretions at the time of admission significantly reduced nosocomial transmission. Because patient care practices play such an important role in the control of viral infections, this effect may have been enhanced by an increased awareness among hospital staff. Significantly fewer nosocomial infections occurred in the pediatric intensive care unit than in the ward for younger children before screening was instituted. The neonatal intensive care unit also had fewer subsequent nosocomial infections. This change may relate to decreased introduction of RSV into these specialized units, a higher level of routine patient care practices, the placement of infants in incubators, and the hospitalization of children older than 3 years of age in the pediatric intensive care unit, as well as other confounding variables. The persistence of nosocomial transmission despite increased staff awareness in the neonatal and pediatric intensive care units, where assignment to cohorts was not possible, suggests that decreased opportunity for transmission, not heightened awareness, is the major benefit of RSV screening and use of cohorts. We acknowledge the contributions of house staff and nursing staff, who provided diligent care for patients under often trying circumstances. REFERENCES
1. Loda FA, Clyde WA Jr, Glezen WP, et al. Studies on the role of viruses, bacteria, and M. pneumoniae as causes of lower respiratory tract infectionsin children. J PEDIATR1968;72:16176. 2. Kim HW, Arrobio JO, Brandt CD, et al. Epidemiologyof respiratory syncytial virus infection in Washington, D.C.I. Importance of the virus in different respiratory tract disease syndromes and temporal distribution of infection.Am J Epidemiol 1973;98:216-25. 3. Parrot RH, Kim HW, Brandt CD, Chanock RM. Respiratory syncytial virus in infants and children. Prev Med 1974;3:47380. 4. MacDonald NE, Hall CB, Suffin SC, Alexson C, Harris J, Manning JA. Respiratory syncytial virus infection in infants with congenital heart disease. N Engl J Med 1982;307:397400. 5. Bruhn FW, Mokrohisky ST, Mclntosh K. Apnea associated with respiratory syncytial virus infection in young infants. J PEDIATR1977;90:382-6. 6. Church NR, Anas NG, Hall CB, Brooks JG. Respiratory syncytial virus related apnea in infants: demographics and outcome. Am J Dis Child 1984;138:247-50. 7. Hall CB, Powell KR, MacDonald NE, et al. Respiratory syncytial virus infection in children with compromised immune function. N Engl J Med 1986;315:77-81. 8. Chandwani S, l~orkowsky W, Krasinski K, Lawrence R, Be-
K r a s i n s k i et al.
The Journal o f Pediatrics June 1990
benroth D, Moore T. Clinical features of respiratory syncytial virus infection in human immunodeficiency virus infected children [Abstract WP141]. Third International Conference on AIDS, Washington, D.C,, U.S. Department of Health and Human Services (with the World Health Organization), 1987:133. Krasinski K. Severe respiratory syncytial virus infection: clinical features, nosocomial acquisition and outcome. Pediatr Infect Dis 1985;4:250-7. Hall CB, Douglas RG, Geiman JM, Messner MK. Nosocomial respiratory syncytial virus infections. N Engl J Med 1975; 293:1343-6. Hall CB, Douglas RG Jr. Nosocomial respiratory syncytial virus infections: should gowns and masks be used? Am J Dis Child 1981;135:512-5. Murphy D, Todd JK, Chao RK, et al. The use of gowns and masks to control respiratory illness in pediatric hospital personnel. J PEDIATR 1981;99:746-50.
13. LeClair J, Freeman J, Sullivan B, Crowley CM, Goldman DA. Prevention of nosocomial respiratory syncytial virus infections through compliance with glove and gown isolation precautions. N Engl J Med 1987;317:329-34. 14. Snydman Dr, Greer C, Meissner HC, Mclntosh K. Prevention of nosocomial transmission of respiratory syncytial virus in a newborn nursery. Infect Control Hosp Epidemiol 1988;9: 105-8. 15. Gala CL, Hall CB, Schnabel KC, et al. The use of eye-nose goggles to control nosocomial respiratory syncytial virus infection. JAMA 1986;256:2706-8. 16. Garner JS, Simmons BP. Guidelines for isolation precautions in hospitals. Infect Control 1983;4(suppl):245-325. 17. Albert RK, Condie F. Handwashing patterns in medical intensive care units. N Engl J Med 1981 ;304:1465-6.
FELLOWSHIPS Available fellowships in pediatric subspecialties and those for general academic pediatric training are listed once a year, in May, in THE JOURNAL OF PEDIATRICS. Each October, forms for listing such fellowships are sent to the Chairman of the Department of Pediatrics at most major hospitals in the United States and Canada. Should you desire to list fellowships, a separate application must be made each year for each position. All applications must be returned to Mosby-Year Book, Inc., by February 15 of the listing year to ensure publication. Additional forms will be supplied on request from the Journal Editing Department, Mosby-Year Book, Inc., 11830 Westline Industrial Drive, St. Louis, M O 63146-3318/314-872-8370.