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T.B. ventilation control: Working with engineering technology and hepa filters
Abstracts NOSOCOMIAL TRANSMISSION OF MTUBERCULOSIS (MTBI: INVESTIGATION AND CONTROL BY PPD SKIN TESTING. R. Lowell, MD,* M. Nowacki, RN. Medical College of Georgia Hospital, Augusta, GA. Nosoconual transmission of MTB is an mcreasing epidemiologic problem because of muk-drug resistance. We investigated the nosocomial transmission of MTB when a health care worker (HCW) developed active pulmonary TB. A comparison of HCW PPD skin testing tn 1990 and 1991 revealed the rate of conversion increased dramatically from 0.4% to I .2% (chi square = 13.9, p=O.OOOZ). Three circles of contacts with the Infected HCW were defined: (A) those working on the same unit and shift as the HCW (n=62), (B) those with intermediate level of exposure @=X7), and (C) those wttk less than 8 hours/week exposure (N=227). The PPD conversion rates were 9.7%, 3.4%, and 1.3%, respectively. The rate for only group A was significantly higher than the 1991 conversion rate (Chi square = 19.4, p=O.OOOO’). Two HCWs in group A had unrecognized active TB. Isolates of 7 patients with pulmonary TB in the 8 months prior to the HCW’s diagnosis were reviewed. SIX were sensitive to all agents, as was the HCW’s isolate. The remainmg isolate was resistant to 2.0 mcgiml of streptomyctn Preliminary restriction fragment length polymorphism (RFLP) analysis revealed trio clear association between any one patient and the HCW. Our findings support the use of outbreak-focused and routine skin testing as essential TB control measure in the hospital.
April
1993
DRAMATIC REDUCTION OF EMPLOYEE PPD CONVERSIONS RATE AFTER IMPLEMENTATION OF NYSiCDC TB CONTROL GUIDELINES IN AN URBAN HOSPITAL. P. Fella, RN, M(ASCP), CIC,* P. Rivera, RN, BA, CIC, C. Maloney. ADN, C. Randolph, RN, I<. Squires, MD, K. Sepkowitr, MD. St. Glare’s Hospital and Health Center, New York, NY.
Issue/Problem: Nosocomial spread of TB to other patients and to hospital workers is a major problem in New York City. The NYSiCDC recommendations for prevention of tuberculosis transmission include environmental controis (negative pressure rooms, dust-tilters with Ultra violet lights and ultra-filtration masks); prompt placement of suspected patients into respiratory isolahon; closure of patient room doors; frequent teaching sessions on TB control; and frequent (up to every 6 month) PPD testing of all employees with patient contact. Methods: Prospective review of PPD conversion rates among employees at St. Glare’s Hospital... Results: In the first 3 months of 1991. prior to implementation of NYS/CDC TB control measure, 15156 (27%) of employees had documented PPD conversion. During the remainder of 1991, NYSiCDC TB control recommendations were fully implemented in 1992, after full implementation of NYS/CDC recommendations, the conversion rate for employees decreased to 21/446 (4.7%) @< 0.001). Conclusion: Implementation of NYSiCDC recommendakons resulted in a dramatic decrease in PPD convewon among employees. Our data does not indicate that implementation of NIOSH recommendations for personal respiratory pact is warranted, as long as strict adherence to NYSiCDC recommendations are maintained.
T.B. VENTILATION CONTROL: WORKING WITH ENGINEERING TECHNOLOGY AND HEPA FILTERS. L. Herring, RN, MSA, CIC,* K. McNamara, RN, CIC, M. Kelly, RN. The Methodist Hospital, Brooklyn, NY. In 1989, a 515 bed community hospttal noted a 100% increase (from 21 to 42 cases per year) in patients admitted to the hospital with active tuberculosis. During 1990, the hospital experienced its first multiple-drug-resistant (MDR) T.B. isolate in an obstetrical patient and the CDC issued guidelines for TB treatment and control. The tmulttdisciplinary Infection Control Commntee was aware of the importance of placing T.B. patients in private rooms with negative pressure, to prevent contamination of the enwronment outside the isolation room. The number of suspected or confirmed T.B. patients outnumbered the availability of private, negative pressure rooms. To address tllis issue, our Director of Engineering, invented the Microcon Air Purifier (MAP), a portable high eftictency particulate air (HEPA) filter. A wooden prototype was displayed at the Infection Control Committee Meeting. The MAP draws air m at 360” and passes it through a HEPA filter that elimtnates 99.97% of all airborne particles 0.3 imicrons or larger. Tke HEPA filter reduces the concentration of TB Bacilli by achievmg 30 air exchanges per hour. The hospital obtained 10 HEPA tilters. A videotape was [made demonstrating the efficiency of the units. The staff was mserviced on TB and the use of the HEPA filters. We concluded that by using the MAP HEPA tilter, we achieved our goal of preventing contamination of the environment outside the isolation room even when a negative pressure room was not available.
RELIABILITY OF INTERPRETATION OF TUBERCULIN TESTING IN THE ELDERLY: IMPLICATIONS FOR PRACTICE. A. McGeer. MD, M McArthur: RN, CIC,* I.G. Naglie, MD. M. Naus, MD, W. Goid, MD, A.E. Simor, MD. Princess Margaret, Mount Smai and Toronto Hospitals and Ontario Ministry of Health, Toronto, Canada. To assess the feaslbikty of measuring the incidence of tubercuiour infection in elderly residents of LTCFs by serial tubercuhn (TB) skin lesting, we had each of 5 trained readers interpret the skin tests of 435 residents of 2 LTCFs. Two methods were used (pen method of Sokol versus CDC recommended method). Readers recorded both transverse and vertical diameters of induration for each test. Of the 435 skin tests, 32% had some degree of induration and 10% (range 8.5 12.9% by different readers) were positive (>lOinm). Reliabikty was not different for the two readmg methods, and only mmimally unproved by takmg the mean of two diameters versus only one. Agreement between pznrs of readers usmg categories of tests (positwe YS negatwe, or groups at Smm mtervals) was moderate to good when assessed by kappa statistics values ranged from 0.60.8. ‘However, for the 5 readers, the mear range of an mdividuai test readmgs was rhmm. This vartation in interpretation imay have a significant impact on the estimated rate of infection. Estimates of false positwe “conversioin” rates created by having a second reader interpret the test are as follows:
Definition
GROUP A STREPTOCOCCAL (GAS) CELLULITIS IN A NURSING HOME MAY BE A SENTINEL EVENT. D. Cann, RN,* K. Green, RN, CIC, A. McGeer, MD, S. Striver, RT, S. Betsckel, BSc, C. Goldman, RN, CIC, M. MeArthur, RN, CIC, B. Schwartz, MD, D.E. Low, MD. Princess Margaret and Mount Sinai Hospitals, Toronto, Canada. Contact follow up of a patient wtth a severe invasive GAS infection identified an associated cluster of cellulitis in staff and residents of a nursing home. In an 11 week period, 10184 (12%) residents and 2185 (2.4%) staff developed cellulitis: 67% of cases were culture confirmed GAS (25% no culture, 8% negative). Illness in the index patient began as celluliris during week Il. Investigations included throat and skin lesion swabs on all residents and staff. 5/84 (6%) residents and 1185 (1.2%) staff had asymptomatic pkaryngeal carriage. The staff member subsequently developed symptoms. 7184 residents and 17185 staff had open skin lesions; one resident and two staff were culture positive for GAS. All three developed celiulitis within 5 days of culture, All isolates were identical by pulse-field gel restriction and endonuclease analysx We found no evidence of closer contact among cases than between cases and control. In comparison, in a nxsing home with one known case of invasive GAS disease 1124 (4.2%) staff had asymptoma!tc pkaryngeal carriage and none of 55 residents had posittve cultures. In a home with no documented GAS infections, we found no positive skin or throat cultures for GAS in residents of staff. As part of another study, prospective surveillance for mfection in 10 nursing Ihomes (4800 resident-months) revealed 11112 cases of GAS cellulitis in an unrecognized cluster. In view of the changing epidemiology of GAS, investigation of a single case of GAS cellulitis may be warranted. Asymptomattc pharyngeal carriers tmay be a significant reservoir.
of conversion
Negative to positive Neg to los, plus 2 Neg to Pos, plus 2
6mm diff l5mm diff
False conversion 2.3% 1.2% 0.15%
rate
i
Rates of false positive conversions in our population may thus be of the same order of magnitude as true infection. The positive predictive value of conversion may be less than 50% in this setting. The sensttivity of a 15 mm increase in induration for this population and the negattve predictive value of Iack of conversion are unknown. Because of these factors, the TB sk(n test is of very limtted value in guiding indiwdual treatmen! decisions, or assessing the epidemiology of tuberculosis in this population.
April
1993
DRAMATIC REDUCTION OF EMPLOYEE PPD CONVERSIONS RATE AFTER IMPLEMENTATION OF NYSiCDC TB CONTROL GUIDELINES IN AN URBAN HOSPITAL. P. Fella, RN, M(ASCP), CIC,* P. Rivera, RN, BA, CIC, C. Maloney. ADN, C. Randolph, RN, I<. Squires, MD, K. Sepkowitr, MD. St. Glare’s Hospital and Health Center, New York, NY.
Issue/Problem: Nosocomial spread of TB to other patients and to hospital workers is a major problem in New York City. The NYSiCDC recommendations for prevention of tuberculosis transmission include environmental controis (negative pressure rooms, dust-tilters with Ultra violet lights and ultra-filtration masks); prompt placement of suspected patients into respiratory isolahon; closure of patient room doors; frequent teaching sessions on TB control; and frequent (up to every 6 month) PPD testing of all employees with patient contact. Methods: Prospective review of PPD conversion rates among employees at St. Glare’s Hospital... Results: In the first 3 months of 1991. prior to implementation of NYS/CDC TB control measure, 15156 (27%) of employees had documented PPD conversion. During the remainder of 1991, NYSiCDC TB control recommendations were fully implemented in 1992, after full implementation of NYS/CDC recommendations, the conversion rate for employees decreased to 21/446 (4.7%) @< 0.001). Conclusion: Implementation of NYSiCDC recommendakons resulted in a dramatic decrease in PPD convewon among employees. Our data does not indicate that implementation of NIOSH recommendations for personal respiratory pact is warranted, as long as strict adherence to NYSiCDC recommendations are maintained.
T.B. VENTILATION CONTROL: WORKING WITH ENGINEERING TECHNOLOGY AND HEPA FILTERS. L. Herring, RN, MSA, CIC,* K. McNamara, RN, CIC, M. Kelly, RN. The Methodist Hospital, Brooklyn, NY. In 1989, a 515 bed community hospttal noted a 100% increase (from 21 to 42 cases per year) in patients admitted to the hospital with active tuberculosis. During 1990, the hospital experienced its first multiple-drug-resistant (MDR) T.B. isolate in an obstetrical patient and the CDC issued guidelines for TB treatment and control. The tmulttdisciplinary Infection Control Commntee was aware of the importance of placing T.B. patients in private rooms with negative pressure, to prevent contamination of the enwronment outside the isolation room. The number of suspected or confirmed T.B. patients outnumbered the availability of private, negative pressure rooms. To address tllis issue, our Director of Engineering, invented the Microcon Air Purifier (MAP), a portable high eftictency particulate air (HEPA) filter. A wooden prototype was displayed at the Infection Control Committee Meeting. The MAP draws air m at 360” and passes it through a HEPA filter that elimtnates 99.97% of all airborne particles 0.3 imicrons or larger. Tke HEPA filter reduces the concentration of TB Bacilli by achievmg 30 air exchanges per hour. The hospital obtained 10 HEPA tilters. A videotape was [made demonstrating the efficiency of the units. The staff was mserviced on TB and the use of the HEPA filters. We concluded that by using the MAP HEPA tilter, we achieved our goal of preventing contamination of the environment outside the isolation room even when a negative pressure room was not available.
RELIABILITY OF INTERPRETATION OF TUBERCULIN TESTING IN THE ELDERLY: IMPLICATIONS FOR PRACTICE. A. McGeer. MD, M McArthur: RN, CIC,* I.G. Naglie, MD. M. Naus, MD, W. Goid, MD, A.E. Simor, MD. Princess Margaret, Mount Smai and Toronto Hospitals and Ontario Ministry of Health, Toronto, Canada. To assess the feaslbikty of measuring the incidence of tubercuiour infection in elderly residents of LTCFs by serial tubercuhn (TB) skin lesting, we had each of 5 trained readers interpret the skin tests of 435 residents of 2 LTCFs. Two methods were used (pen method of Sokol versus CDC recommended method). Readers recorded both transverse and vertical diameters of induration for each test. Of the 435 skin tests, 32% had some degree of induration and 10% (range 8.5 12.9% by different readers) were positive (>lOinm). Reliabikty was not different for the two readmg methods, and only mmimally unproved by takmg the mean of two diameters versus only one. Agreement between pznrs of readers usmg categories of tests (positwe YS negatwe, or groups at Smm mtervals) was moderate to good when assessed by kappa statistics values ranged from 0.60.8. ‘However, for the 5 readers, the mear range of an mdividuai test readmgs was rhmm. This vartation in interpretation imay have a significant impact on the estimated rate of infection. Estimates of false positwe “conversioin” rates created by having a second reader interpret the test are as follows:
Definition
GROUP A STREPTOCOCCAL (GAS) CELLULITIS IN A NURSING HOME MAY BE A SENTINEL EVENT. D. Cann, RN,* K. Green, RN, CIC, A. McGeer, MD, S. Striver, RT, S. Betsckel, BSc, C. Goldman, RN, CIC, M. MeArthur, RN, CIC, B. Schwartz, MD, D.E. Low, MD. Princess Margaret and Mount Sinai Hospitals, Toronto, Canada. Contact follow up of a patient wtth a severe invasive GAS infection identified an associated cluster of cellulitis in staff and residents of a nursing home. In an 11 week period, 10184 (12%) residents and 2185 (2.4%) staff developed cellulitis: 67% of cases were culture confirmed GAS (25% no culture, 8% negative). Illness in the index patient began as celluliris during week Il. Investigations included throat and skin lesion swabs on all residents and staff. 5/84 (6%) residents and 1185 (1.2%) staff had asymptomatic pkaryngeal carriage. The staff member subsequently developed symptoms. 7184 residents and 17185 staff had open skin lesions; one resident and two staff were culture positive for GAS. All three developed celiulitis within 5 days of culture, All isolates were identical by pulse-field gel restriction and endonuclease analysx We found no evidence of closer contact among cases than between cases and control. In comparison, in a nxsing home with one known case of invasive GAS disease 1124 (4.2%) staff had asymptoma!tc pkaryngeal carriage and none of 55 residents had posittve cultures. In a home with no documented GAS infections, we found no positive skin or throat cultures for GAS in residents of staff. As part of another study, prospective surveillance for mfection in 10 nursing Ihomes (4800 resident-months) revealed 11112 cases of GAS cellulitis in an unrecognized cluster. In view of the changing epidemiology of GAS, investigation of a single case of GAS cellulitis may be warranted. Asymptomattc pharyngeal carriers tmay be a significant reservoir.
of conversion
Negative to positive Neg to los, plus 2 Neg to Pos, plus 2
6mm diff l5mm diff
False conversion 2.3% 1.2% 0.15%
rate
i
Rates of false positive conversions in our population may thus be of the same order of magnitude as true infection. The positive predictive value of conversion may be less than 50% in this setting. The sensttivity of a 15 mm increase in induration for this population and the negattve predictive value of Iack of conversion are unknown. Because of these factors, the TB sk(n test is of very limtted value in guiding indiwdual treatmen! decisions, or assessing the epidemiology of tuberculosis in this population.