Monitoring and preventing healthcare-associated infections. The CDC approach.

The Centers for Disease Control and Prevention (CDC) is a federal agency in the United States charged with promoting health and quality of life by preventing and controlling disease, injury, and disability. Healthcare-associated infections (HAIs) are associated with substantial morbidity, mortality, and cost. To protect patients and health care personnel and promote safety, quality, and value of the health care delivery system in the United States, CDC provides leadership in surveillance, outbreak investigations, laboratory support and research, and prevention programs. Information from CDC programs are used to (1) assess the magnitude, trends, and risk factors of HAIs; (2) detect new patterns and mechanisms of antimicrobial resistance; (3) detect infections/adverse events related to new procedures performed in healthcare; and (4) develop new strategies to prevent HAIs. The CDC approach to monitor and prevent HAIs is described.

The nature and frequency of blood contacts among home healthcare workers.

OBJECTIVE: To estimate the frequency of, and assess risk factors for, percutaneous, mucous membrane, and cutaneous blood contacts sustained by healthcare workers (HCWs) during the delivery of infusion therapy and the performance of procedures involving sharp instruments in the home setting. DESIGN: Prospective surveillance of percutaneous, mucous membrane, and cutaneous blood contacts. SETTING: Eleven home healthcare agencies in the United States and Canada from August 1996 through June 1997. PARTICIPANTS: HCWs who provided home infusion therapy or performed procedures using hollow-bore needles and other sharp instruments in the home setting. METHODS: Each participating worker recorded information about the procedures performed and blood contacts experienced during each of his or her home visits for a 2- to 4-week period using standard questionnaires. HCWs also completed questionnaires regarding job duties, reporting of previous occupational blood contacts, and their use of protective barriers in the home setting. RESULTS: Participating HCWs provided information about 33,606 home visits. A total of 19,164 procedures were performed during 14,744 procedure visits. Fifty-three blood contacts occurred during these visits, for a blood-contact rate of 2.8 blood contacts per 1,000 procedures and 0.6 percutaneous injuries per 1,000 procedures with needles or lancets. Gloves were worn for 52%, masks for 5%, gowns for 3%, and protective glasses or goggles for 2% of all procedure visits. HCWs used barriers for 53% of visits during which at least 1 procedure was performed and for 27% of other visits. CONCLUSIONS: HCWs involved in home health care are at risk for blood contact. Infection control barrier use was low in our study. The majority of skin contacts could have been prevented by glove use.

[Effect of nosocomial bacteremia caused by oxacillin-resistant Staphylococcus aureus on mortality and length of hospitalization]. / Efeito da infecção hospitalar da corrente sanguínea por Staphylococcus aureus resistente à oxacilina sobre a letalidade e o tempo de hospitalização.

OBJECTIVES: To identify the attributed mortality rate of bloodstream hospital infection by Staphylococcus aureus resistant to methicillin (MRSA) and its effect on length of hospital stay. DESIGN: Case-control study. SETTING: Hospital São Paulo da Universidade Federal de São Paulo, a 660-bed, tertiary-care teaching hospital in São Paulo, Brazil. PATIENTS: Seventy one adults patients with hospital-acquired MRSA bacteremia diagnosed between January 1, 1991, and September 30, 1992, and 71 MRSA-free controls were matched by the following criteria: age, sex, underlying disease, surgical procedure, same risk time and admission date. RESULTS: The incidence of patients with hospital sepsis by MRSA accounted for 73.22% of the patients with hospital bloodstream infection by Staphylococcus aureus. The mortality rate of the cases was 56.33 (40/71) and 11.26 (8/71) of the controls. The attributable mortality rate was 45.07% (OR = 17.0; IC 95% = 3.58-202.26; p = 0.000001). The length of hospital stay median time was of 32.55 days for the cases and 29.75 for the controls (p = 0.32). CONCLUSION: A high level of sepsis by MRSA was observed in all the Staphylococcus aureus bacteremia. The bloodstream hospital infection by MRSA itself does provide a high level of mortality independently from the patients base disease, without however, increasing their hospital length of stay.

Efeito da infecçäo hospitalar da corrente sanguínea por Staphylococcus aureus resistente à oxacilina sobre a letalidade e o tempo de hospitalizaçäo / The effect of bloodstream hospital infection by Staphylococcus aureus resistant to oxacillin on the mortality and the length of hospitalization

Objetivo. Determinar a letalidade atribuída à infecçao hospitalar da corrente sangüínea (IHCS) por Staphylococcus aureus resistente à oxacilina (SARO) e seu efeito sobre o tempo de hospitalizaçao. Casuística e Métodos. Estudo tipo caso controle envolvendo 71 pares de pacientes adultos internados em hospital de ensino no período de janeiro de 1991 a setembro de 1992, pareados para os seguintes critérios: idade, sexo, doença de base, procedimento cirúrgico, mesmo período de risco e data de admissao. Resultados. A incidência de pacientes com sepses hospitalar por SARO representou 73,22 por cento entre aqueles que desenvolveram bacteremia por Staphylococcus aureus. A taxa de letalidade dos casos foi de 56,33 por cento (40/71). Oito controles morreram, o que corresponde à taxa de letalidade de 11,26 por cento (8/71). A letalidade atribuída à infecçao hospitalar da corrente sangüínea por SARO foi de 45,07 por cento (OR=17,0; IC 95 por cento=3,58 - 202,26; p=0,000001). Os casos permaneceram, em média, 32,5 dias internados no hospital, enquanto que os controles 29,7 dias (p=0,32). Conclusoes. Observou-se elevada proporçao de sepses por SARO entre todas as bacteremias por Staphylococcus aureus. A IHCS por SARO acarreta, por si só, uma alta taxa de letalidade, independentemente da doença que causou a internaçao, sem contudo, aumentar o tempo de permanência hospitalar.

Liver failure and death after exposure to microcystins at a hemodialysis center in Brazil.

BACKGROUND: Hemodialysis is a common but potentially hazardous procedure. From February 17 to 20, 1996, 116 of 130 patients (89 percent) at a dialysis center (dialysis center A) in Caruaru, Brazil, had visual disturbances, nausea, and vomiting associated with hemodialysis. By March 24, 26 of the patients had died of acute liver failure. METHODS: A case patient was defined as any patient undergoing dialysis at dialysis center A or Caruaru's other dialysis center (dialysis center B) during February 1996 who had acute liver failure. To determine the risk factors for and the source of the outbreak, we conducted a cohort study of the 130 patients at dialysis center A and the 47 patients at dialysis center B, reviewed the centers' water supplies, and collected water, patients' serum, and postmortem liver tissue for microcystin assays. RESULTS: One hundred one patients (all at dialysis center A) met the case definition, and 50 died. Affected patients who died were older than those who survived (median age, 47 vs. 35 years, P<0.001). Furthermore, all 17 patients undergoing dialysis on the Tuesday-, Thursday-, and Saturday-night schedule became ill, and 13 of them (76 percent) died. Both centers received water from a nearby reservoir. However, the water supplied to dialysis center B was treated, filtered, and chlorinated, whereas the water supplied to dialysis center A was not. Microcystins produced by cyanobacteria were detected in water from the reservoir and from dialysis center A and in serum and liver tissue of case patients. CONCLUSIONS: Water used for hemodialysis can contain toxic materials, and its quality should therefore be carefully monitored.

A case-control study of HIV seroconversion in health care workers after percutaneous exposure. Centers for Disease Control and Prevention Needlestick Surveillance Group.

BACKGROUND: The average risk of human immunodeficiency virus (HIV) infection after percutaneous exposure to HIV-infected blood is 0.3 percent, but the factors that influence this risk are not well understood. METHODS: We conducted a case-control study of health care workers with occupational, percutaneous exposure to HIV-infected blood. The case patients were those who became seropositive after exposure to HIV, as reported by national surveillance systems in France, Italy, the United Kingdom, and the United States. The controls were health care workers in a prospective surveillance project who were exposed to HIV but did not seroconvert. RESULTS: Logistic-regression analysis based on 33 case patients and 665 controls showed that significant risk factors for seroconversion were deep injury (odds ratio= 15; 95 percent confidence interval, 6.0 to 41), injury with a device that was visibly contaminated with the source patient's blood (odds ratio= 6.2; 95 percent confidence interval, 2.2 to 21), a procedure involving a needle placed in the source patient's artery or vein (odds ratio=4.3; 95 percent confidence interval, 1.7 to 12), and exposure to a source patient who died of the acquired immunodeficiency syndrome within two months afterward (odds ratio=5.6; 95 percent confidence interval, 2.0 to 16). The case patients were significantly less likely than the controls to have taken zidovudine after the exposure (odds ratio=0.19; 95 percent confidence interval, 0.06 to 0.52). CONCLUSIONS: The risk of HIV infection after percutaneous exposure increases with a larger volume of blood and, probably, a higher titer of HIV in the source patient's blood. Postexposure prophylaxis with zidovudine appears to be protective.

Bloodborne pathogen transmission in health care workers. Risks and prevention strategies.

Occupational transmission of hepatitis B virus (HBV), hepatitis C virus, and HIV has been documented. The risk for occupationally transmitted infection varies for these three viruses. Despite effective pre- and postexposure prophylaxis for HBV and recent recommendations for postexposure chemoprophylaxis after an HIV exposure, the best approach to prevent occupational bloodborne infection is the prevention of blood exposures. Epidemiologic data of percutaneous injuries and other blood contacts have provided the basis for prevention strategies. These strategies include the development of improved engineering controls, work practices, and personal protective equipment.

Percutaneous exposures to HIV-infected blood. Among dental workers enrolled in the CDC Needlestick Study.

The authors found that 19 percutaneous exposures among dental workers occurred both during and after use of instruments such as syringe needles and scalers. Specific information about the device and action associated with an exposure is important for prevention efforts, including safer instruments and work practices. Most of these exposures probably involved smaller, rather than larger, amounts of blood infected with the human immunodeficiency virus. To our knowledge, none of the exposures resulted in HIV transmission to an enrolled dental worker.

An outbreak of handscrubbing-related surgical site infections in vascular surgical procedures.

OBJECTIVE: To investigate an outbreak of surgical site infections (SSI) in a vascular surgery unit. SETTING: A 60-bed unit of vascular surgery, where surgeons performed an average of 30 operations per month at the Hospital do Servidor Público Estadual, a 1,000-bed tertiary care hospital in São Paulo, Brazil. DESIGN: We included in the case group nine patients who had limb amputations or arterial reconstructions, October 16 through 23, 1992. We included in the control group patients whose operations were performed within 30 days of the outbreak period. Control patients were matched for sex and type of operation. RESULTS: Six of 9 case patients experienced SSI, as compared with 3 of 18 control patients (P = .026) and 28 of 244 patients in the pre-epidemic period (P = .0002). Risk factors were identical for case and control groups. Factors assessed were American Society of Anesthesiology (ASA) status, duration of surgery, wound class, emergency status, remote site infections, preoperative length of stay, use of prophylactic antibiotics, and underlying diseases. Possible common sources also were analyzed. No differences were observed concerning hair removal, preoperative shower, wound dressing, and surgical team present in the operating room. During the outbreak period, the operating room was not provided with povidone-iodine, used in our hospital for skin cleansing and handscrubbing. Surgeons from all departments, including vascular surgery, used 2% iodine with 70% alcohol for skin cleansing. Surgeons from other departments used this iodine solution for handscrubbing, but the vascular surgeons used plain soap for handscrubbing. No increases in SSI rates were reported in other services. Comparison of case and control groups for handscrubbing was statistically significant (P < .00001). After reinstitution of povidone-iodine, only one SSI was diagnosed in 13 vascular procedures. CONCLUSIONS: Although we could not demonstrate definitely that scrubbing with plain soap was related to SSI, we found a strong suggestion of this association.

Validation of surgical wound classification in the operating room.

OBJECTIVE: To determine the accuracy with which circulating nurses (CNs) classify surgical procedures by risk of contamination in the operating room. DESIGN: Classification of surgical procedures by CNs was compared with the classification of surgical procedures by a physician observer. SETTING: University-affiliated, tertiary care hospital. METHODS: Circulating nurses used the traditional wound classification system of clean, clean-contaminated, contaminated, and dirty-infected to classify surgical wounds in the operating room. A physician remained in the operating room throughout each of 100 surgical procedures and simultaneously classified surgical wounds without the knowledge of the CNs. RESULTS: Classification of surgical wounds by CNs was compared with classification by the physician observer for 50 cases in general surgery and 50 cases in trauma surgery. Compared with the physician observer, the overall accuracy of classification by CNs was 88% (95% confidence interval [CI] of 81.6% to 94.4%; Kappa statistic, 0.83). Classification of surgical wounds was more difficult in trauma surgery (accuracy of 82%) than in general surgery (accuracy of 94%). Accuracy increased for both services when surgical wounds were classified into just two categories (clean or clean-contaminated versus contaminated or dirty-infected). CONCLUSIONS: Surgical wounds can be classified in the operating room with a high degree of accuracy by CNs. Classification was more difficult in trauma than in general surgery, but classification in trauma surgery improved with feedback to and additional education of CNs. The accuracy of classification by CNs was even higher when classifications were divided into just two categories.

Validation of surgical wound surveillance.

OBJECTIVE: To determine the sensitivity and specificity of standard infection control surveillance techniques for the identification of surgical wound infections. DESIGN: Surveillance data collected by three infection control practitioners (ICPs) was compared to surveillance data collected simultaneously by a gold standard observer. SETTING: University-affiliated, tertiary care hospital. METHODS: Using standard infection control surveillance techniques (chart review and discussions with patients' nurses and physicians), ICPs collected surveillance data on patients on the General Surgery and Trauma Surgery Services on days 4 and 7 after surgery and then weekly for 30 days or until patients were discharged from the hospital. Simultaneously, a hospital epidemiologist collected surveillance data and examined each patient's wound daily. RESULTS: Nine hundred twenty-five surgical patients including 537 trauma cases and 388 elective general surgery cases were followed postoperatively. The ICPs identified 67 surgical wound infections, and the hospital epidemiologist identified 80 surgical wound infections for a sensitivity of 83.8% with a 95% confidence interval (CI95) of 75.7% to 91.9%. Specificity was 99.8% with a CI95 of 99% to 100%. The sensitivity was the same for trauma surgery and general surgery, but incisional wound infections were more difficult to identify than deep wound infections. During a second validation period, sensitivity was 92.3% with a CI95 of 62% to 100%. CONCLUSIONS: Standard infection control surveillance techniques have the same sensitivity for detection of surgical wound infections as they do for identification of other nosocomial infections. Accurate data on surgical wound infections can be collected without direct examination of surgical wounds.

Distribution and analysis of 8,268 nosocomial infections at the Hospital Säo Paulo: 1985 to 1989

Since 1985, the Hospital Säo Paulo has a nosocomial infection (NI) control program. The NI control commitee acts in all sectors of the hospital, performing active epidemiologic surveillance. During a period of 58 months (March, 1985 to december, 1989) 8, 268 NI were identified in the 86,849 hospiytalized patients, representing a rate of 9.5 por cento. The most prevalent NI was that of the respiratory tract 21.8 per cent (1,803) followed by: surgical wound 16.7 per cent (1,383), urinary tract 12.2 per cent (1,011), bloodstream 11.2 per cents (924) and other sites 38 per cent (3,147). There was a significant fall in NI rate for each site, mainly respiratory and urinary tract. The patients admitted to the General Intensive Care Unit represented 11 per cent (897) of all detected NI. Some of most frequently isolated agents were: S. aureus 19 per cent (915), E. coli 14 per cent (673), Klebsiella spp 12.4 per cent (598) and pseudomonas spp 12.2 per cent (587)