Tuberculosis and tuberculin quality: best intentions, misleading results.

OBJECTIVE: To compare the performance of three purified protein derivative (PPD) formulations: Tubersol (Connaught); RT23, Statens Serum Institut (SSI); and RT23, Mexico, tested in Mexican populations at low and high risk for tuberculosis (TB). DESIGN: A double-blinded clinical trial. SETTING: A university hospital in Mexico City. PARTICIPANTS: The low-risk population was first or second-year medical students with no patient contact; the high-risk population was healthcare workers at a university hospital. METHODS: Each of the study subjects received the three different PPD preparations. Risk factors for TB, including age, gender, occupation, bacille Calmette-Guérin (BCG) status, and TB exposure, were recorded. A 0.1-mL aliquot of each preparation was injected in the left and right forearms of volunteers using the Mantoux technique. Blind readings were done 48 to 72 hours later. Sensitivity and specificity were calculated at 10 mm of induration using Tubersol as the reference standard. The SSI tested the potency of the different PPD preparations in previously sensitized guinea pigs. RESULTS: The low-risk population had a prevalence of positive PPD of 26%. In the low-risk population, RT23 prepared in Mexico, compared to the 5 TU of Tubersol, had a sensitivity of 51%, a specificity of 100%, a positive predictive value of 100%, and a negative predictive value of 86%. The RT23 prepared at the SSI had a sensitivity of 69%, a specificity of 99%, a positive predictive value of 95%, and a negative predictive value of 90%. In the high-risk population, the prevalence of positive PPD was 57%. The RT23 prepared in Mexico had a sensitivity of 33%, a specificity of 100%, and a positive predictive value of 53%; the RT23 prepared at the SSI had a sensitivity of 91%, a specificity of 98%, a positive predictive value of 98%, and a negative predictive value of 89%. RT23 used in Mexico had a potency of only 23% of that of the control. There was no statistical association among those with a positive PPD, irrespective of previous BCG vaccination (relative risk, 0.97; 95% confidence interval, 0.76-1.3;P=.78). CONCLUSIONS: Healthcare workers had twice the prevalence of positive PPD compared to medical students. RT23 prepared in Mexico had a low sensitivity in both populations compared to 5 TU of Tubersol and RT23 prepared at the SSI. Previous BCG vaccination did not correlate with a positive PPD. Low potency of the RT23 preparation in Mexico was confirmed in guinea pigs. Best intentions in a TB program are not enough if they are not followed by high-quality control.

[An outbreak of Salmonella gastroenteritis among hospital workers]. / Brote por Salmonella enteritidis en trabajadores de un hospital.

OBJECTIVE: To describe and identify the causes of an outbreak of Salmonella enteritidis gastroenteritis that took place in June 1998, among tertiary care hospital workers, in Mexico City. MATERIAL AND METHODS: Cases were hospital workers who developed diarrhea or fever associated with gastrointestinal symptoms, after a meal at the hospital's dining room on June eight; controls were asymptomatic employees who also ate at the hospital's dining room on the same day. A food questionnaire was applied, and stool samples were obtained from all study subjects, including kitchen personnel. Blood cultures were practiced for febrile patients. Odds ratios with 95% confidence intervals (95% CI) and the chi-squared were used for statistical analysis. Statistical significance was set at p < 0.05. RESULTS: One-hundred-fifty-five workers developed symptoms, but only 129 (83.2%) answered the questionnaire; 150 controls were also studied. The most common symptoms were diarrhea (85%), abdominal pain (84%), cephalea (81.4%), nausea (78.3%), and chills (74.4%). Eight blood cultures were negative; 59 stool cultures (46%) from cases and six (4%) from controls, were positive for Salmonella enteritidis. Egg-covered meat was the suspected source of infection (OR 19.39, 95% CI 9.09-41.4); some other foodstuffs like fruit dessert and yogurt, were significantly more frequent in cases than in controls. Food cultures were all negative. CONCLUSION: This outbreak was probably caused by Salmonella-contaminated foodstuffs (egg-covered meat with potatoes) due to deficient cooking. This report shows the importance of food-quality programs for hospital meals.

Risk factors for candidal bloodstream infections in surgical intensive care unit patients: the NEMIS prospective multicenter study. The National Epidemiology of Mycosis Survey.

To assess risk factors for development of candidal blood stream infections (CBSIs), a prospective cohort study was performed at 6 sites that involved all patients admitted to the surgical intensive care unit (SICU) for >48 h over a 2-year period. Among 4276 such patients, 42 CBSIs occurred (9.82 CBSIs per 1000 admissions). The overall incidence was 0.98 CBSIs per 1000 patient days and 1.42 per 1000 SICU days with a central venous catheter in place. In multivariate analysis, factors independently associated with increased risk of CBSI included prior surgery (relative risk [RR], 7.3), acute renal failure (RR, 4.2), receipt of parenteral nutrition (RR, 3.6), and, for patients who had undergone surgery, presence of a triple lumen catheter (RR, 5.4). Receipt of an antifungal agent was associated with decreased risk (RR, 0.3). Prospective clinical studies are needed to identify which antifungal agents are most protective and which high-risk patients will benefit from antifungal prophylaxis.

Clinical manifestations and survival trends during the first 12 years of the AIDS epidemic in Mexico.

BACKGROUND: Our objective was to evaluate survival trends (1984-1995), the prevalence of AIDS-defining conditions, and the role of treatment with zidovudine and/or prophylaxis with trimethoprim-sulfamethoxazole (TMP-SMX) in survival following AIDS diagnosis. METHODS: We reviewed the clinical charts and postmortem studies of all patients admitted to the HIV Clinic from 1984-1995. Three groups were identified according to the following dates of HIV diagnosis: 1) 1984-1988; 2) 1989-1992, and 3) 1993-1995. RESULTS: We studied 909 charts. During the study period, 744 (81.6%) patients developed AIDS. Median survival increased from 11.7 months in group 1 to 15.4 and 17.5 months in groups 2 and 3, respectively (p <0.05). We observed the following important changes in the frequency of AIDS-defining conditions over the study period: Pneumocystis carinii pneumonia (PCP) decreased from 24.8 to 17 and 14% in groups 1, 2, and 3, respectively, (p = 0.008), and Kaposi's sarcoma (KS), from 31.1 to 10.5 and 13.5% (p <0.001). On the other hand, there was an increase in cytomegalovirus disease with 12.4, 20.4, and 18.6% (p = 0.04) and wasting syndrome with 36, 45, and 57% (p <0.001). In the proportional hazard model for death, zidovudine or TMP-SMX use was associated with a protective effect. CONCLUSIONS: Survival is improving among patients with HIV infection at our institution. The prevalence of AIDS-defining conditions has changed over the last 12 years. There has been a diminution of PCP and KS, whereas cases of CMV disease and wasting syndrome increased.

[Bioterrorism: notes for an agenda in case of the unexpected]. / Bioterrorismo: apuntes para una agenda de lo inesperado.

UNLABELLED: The vulnerability of human populations to chemical, biological, radiological, and nuclear terrorism has been widely discussed but insufficiently studied. Current public health policies are not guided by solid and relevant information to design cost-effective programs for preventing or controlling this kind of incidents in the future. Governmental budgets are insufficient to respond to bioterrorist attacks. To face these threats, developing countries like Mexico should frame strategies and devise specific preventive actions that consider the transmission dynamics of potential infectious agents likely to be used in a bioterrorist attack. PROPOSALS: The international reaction to a biological attack must be supported by international agreements that ban the use of biological agents for warfare and/or defense purposes, as well as on academic and technological exchange for the prevention of bioterrorist attacks. At the national level, the recommendations in the event of a biological attack are: a) establishing a legal defense strategy against bioterrorism; b) implementing education programs as a key strategy for defense against bioterrorism; c) devising a national program of interinstitutional anti-bioterrorist coordination that includes medical emergency assistance and collection of medical forensic evidence; d) including a biological weapon registry in epidemiological surveillance systems; e) implementing a laboratory for biological material analysis related to terrorist incidents; f) devising public health information campaigns, g) assuring the supply of diagnostic testing, special protection, and emergency treatment materials; h) decentralizing alert systems for the timely detection of bioterrorist attacks; i) responding to bioterrorist actions addressed against animals and plants, and j) organizing Ethics Committees in case of urgent events derived from a biological attack. CONCLUSIONS: The proper response to sudden and unexpected events of emergent or unusual infectious diseases involved in a bioterrorist attack requires an adequate public health infrastructure. Modern technology allows the timely identification of multiple infectious agents by nucleic acid analyses and should be widely available in reference laboratories. All these measures require sufficient funding to respond to this potential threat. Resource allocation to respond to bioterrorist attacks must be consonant with their potential public health consequences.

Bloodborne viral infections in patients attending an emergency room in Mexico City: estimate of seroconversion probability in healthcare workers after an occupational exposure.

The frequency of hepatitis C (HCV), hepatitis B (HBV), human immunodeficiency virus (HIV), and human T-cell lymphotropic virus (HTLV) I/II was determined in the emergency room of a teaching hospital. Of 909 patients, 19% had at least one infection; 7.8% had HCV, 6.9% HBV, 3.3% HIV, and 2.8% HTLV I/II. The probability that a healthcare worker would have an accident with an infected patient and seroconvert was 4.99 to 24.9 per 100,000 venipunctures for HBV, 5.6 to 8.4 for HCV, and 0.12-0.16 for HIV in our emergency room.

Epidemiology of nosocomial outbreaks: 14-year experience at a tertiary-care center.

Twelve nosocomial outbreaks over 14 years at a tertiary-care center in Mexico are described. Overall mortality was 25.8%, one half due to pneumonia. The most common organism was Pseudomonas aeruginosa. Incidence was three outbreaks per 10,000 discharges; outbreak-related infections comprised 1.56% of all nosocomial infections. Incidence in the intensive care unit was 10-fold higher.

Prevalence of infections in intensive care units in Mexico: a multicenter study.

OBJECTIVE: To determine the 1-day prevalence of community-acquired, hospital-acquired, or intensive care unit (ICU)-acquired infections in Mexican ICUs. To identify associated risk factors, predominant infecting organisms, and mortality rates. DESIGN: A 1-day point-prevalence study. SETTING: A total of 254 adult ICUs in Mexico. PATIENTS: Adult patients hospitalized in the participating ICUs. RESULTS: A total of 895 patients were studied, of whom 521 patients (58.2%) were infected. Community-acquired infection occurred in 214 patients (23.9%), non-ICU nosocomial infection occurred in 99 patients (11.1%), and 208 patients had at least one ICU-acquired infection (23.2%; 1.45 episodes/patient). The most frequently reported ICU-acquired infections were pneumonia (39.7%), urinary tract infections (20.5%), wound infection (13.3%), and bacteremia (7.3%). The mortality rate for the ICU-acquired infections after 6 wks of follow-up was 25.5%. Multivariate regression analysis showed the following risk factors for ICU-acquired infections: neurologic failure as a primary cause of admission (odds ratio [OR], 1.697; 95% confidence interval [CI], 1.001-2.839); length of stay in ICU (OR, 1.119; 95% CI, 1.091-1.151); number of therapeutic and/or diagnostic interventions during the preceding week (OR, 1.118; 95% CI, 1.016-1.231); peripherally administered infusion of hyperosmolar solutions (OR, 6.93; 95% CI, 2.452-21.661); sedative usage in the preceding week (OR, 1.751; 95% CI, 1.183-2.602); history of an emergency surgery in the preceding month (OR, 1.875; 95% CI, 1.251-2.813). The administration of antimicrobial treatment if there was an infection decreased the risk of death (OR, 0.406; 95% CI, 0.204-0.755). CONCLUSIONS: Evidence of a high frequency of nosocomial infections was found, and potential risk factors for acquiring infections and mortality were identified. Mortality rates according to the hierarchy of the systemic inflammatory response syndrome in Latin American ICUs are reported.

[Tuberculosis in health personnel: importance of surveillance and control programs]. / Tuberculosis en trabajadores de la salud: importancia de los programas de vigilancia y control.

OBJECTIVE: To describe tuberculosis surveillance results among healthcare workers of a tertiary care center. MATERIAL AND METHODS: All medical records of workers from 1992-1998 were reviewed. Demographics, labor, medical history, previous testing, PPD, booster shots and follow-up were analyzed. Statistical analysis was performed with odds ratios, p-values, and 95% confidence intervals. Subgroup analysis were done with chi 2. Kaplan-Meier estimates were used to analyze times to conversion. RESULTS: Surveillance was done in 1617 workers (68% female and 32% male). Mean age was 26.9 +/- 7.6 (15-68) years. Job positions were 30.5% nurses, 14.6% residents and 14.1% interns. Place of origin was Mexico City in 65.8%. BCG vaccination was present in 71.6% and 15.1% had previous PPD. Admission PPD was positive in 39.6%, negative in 48.3% and 12.1% were lost to follow-up. On negatives, 483 booster shots were applied, and 49 additional positives were found. Follow-up was done in 231 workers, of which 100 (43.3%) converted. The mean time for conversion was 22.8 +/- 12.4 months. The conversion rate at twelve months was 20%. Fifty workers received/accepted isoniazid prophylaxis. CONCLUSIONS: A high percentage of workers were PPD-positive; booster shots allowed the detection of an additional 10%. A high conversion rate underscores the need to organize tuberculosis control programs in Mexico.

[Nosocomial infections: secular trends of a control program in Mexico]. / Infecciones nosocomiales: tendencias seculares de un programa de control en México.

OBJECTIVE: To know the trend of nosocomial infections rates at a third level hospital since the beginning of the infection control program until the present and to evaluate the impact in mortality and length of hospital stay. MATERIAL AND METHODS: A study descriptive, retrospective and retrolective was done in a reference hospital providing tertiary care in Mexico City. Recorded data included rates, type of nosocomial infections and distribution of nosocomial infections from the database of Hospital Epidemiology Division between 1991 to 1996. In every patient the degree of severity disease was evaluated according to the McCabe-Jackson's scale, we also collected age and the length of stay. Statistical analysis was done with chi 2 test for tendencies of different evaluated parameters. This study was divided in three periods: before remodel (1991-1993), to remodel (1994-1995) and after remodel (1996). Compared the before remodel period against after remodel period. RESULTS: In the study period, mean nosocomial infections ratio was of 8.6 by 100 discharges, showing a decrease of 20% (p < 0.01). Hospital area with the highest infections rate was ICU (26.9 by 100 discharge), followed by general ward of hospitalization with shared rooms (9.47) and private rooms (7.5). Urinary tract infections was the most frequent (26.6%), followed by surgical wound infection (24.4%), pneumonia (12.1%) and primary bacteremia (9.5%). Rates of urinary tract infections and primary bacteremias had decreased significantly (p < 0.05 and p < 0.00001 respectively), while surgical wound infections and pneumonias increased (p < 0.005 and p < 0.00001 respectively). Associated mortality diminished in 36% (p < 0.00001). The length of stay diminished 42.8%. There was not differences in the severity of disease along this period. CONCLUSIONS: Since the establishment of the nosocomial infections surveillance and control program at the INNSZ on 1985, nosocomial infections rate (56%) and the associated mortality (36%) have diminished. These changes are consequence of the establishment of a nosocomial infections control program and the decrease of length of stay and does not seems to be related to the age or to the severity of the disease of the hospitalized patients.

[Evaluation of a nosocomial infection surveillance program]. / Validación de un programa de vigilancia de infecciones nosocomiales.

OBJECTIVE: To validate the nosocomial infections surveillance system, establish its impact in morbi-mortality. MATERIAL AND METHODS: Surveillance of every single patient admitted during a one month period was done by one of us (DMG). Each possible case was discussed with two other hospital epidemiologists (SPLR, MSRF). This intensive surveillance was compared against the routinely surveillance performed by the nurses. We included all hospitalized patients between 11th July and 12th of August according to CDC (Atlanta, GA) nosocomial infections definitions. Patients were followed everyday and information about age, gender, underlying diagnosis, microorganisms responsible for nosocomial infections, hospital length of stay and mortality. RESULTS: During the study period 429 were admitted, 45 developed a nosocomial infection (cases) and 384 did not (controls). The incidence of nosocomial infections was 10.48 cases/100 discharges. The sensitivity and specificity of the surveillance system was 95.3 and 98.7%, respectively. Mortality in infected was 11.11% and in non infected was 2.4%. The average length of stay was 20 and 11 days for cases and non infected respectively (p < 0.01). Urinary tract infections were the most common NI (42%), secondary bacteremia (14 < or = %), pneumonia (11.11%) and deep surgical site infection (9.25%). The surgical wound infection rates were: 1.3%, 1.9% and 1.9% for clean, clean-contaminated and contaminated wounds. Patients with rapidly fatal diseases had an increased frequency of infections. The microorganisms most commonly isolated were Escherichia coli (28%), Staphylococcus aureus (11.11%), and Pseudomonas aeruginosa (8.6%). The level of antibiotic resistance was in average of 43% for those antibiotics tested. CONCLUSIONS: The sensitivity and specificity of the surveillance system was excellent. Patients with nosocomial infections had an increased length of stay and a higher mortality compared to those without NI. The validation of the surveillance system allows the production of trustable conclusions about nosocomial infections.

[Nosocomial infections and quality of health care]. / Las infecciones nosocomiales y la calidad de la atención médica.

The main objective of a hospital-acquired infections control program is to decrease the risk of acquisition and the morbidity and costs associated. The organization of a team with technical and humanistic leadership is essential. Every infection control program must also develop strategies that allow: a) identification of the problems, b) to establish the importance of each one, c) to determine their causes, d) to develop solutions and e) the evaluation of the recommended solutions. The development of technical and humanistic abilities by the leader and the members of the team, and the use of the tools mentioned above have produced the only validate and highly effective program of quality improvement in the hospital.

Persistence of Legionella pneumophila in a hospital's water system: a 13-year survey.

OBJECTIVE: To describe the molecular epidemiology of Legionella pneumophila infections in the University of Iowa Hospitals and Clinics (UIHC). DESIGN: Molecular epidemiological study using pulsed-field gel electrophoresis (PFGE). SETTING: A large university teaching hospital. ISOLATES: All surviving isolates obtained from culture-proven nosocomial L. pneumophila infections and all surviving isolates obtained from the University of Iowa Hospital and Clinics' water supply between 1981 and 1993. RESULTS: Thirty-three isolates from culture-proven nosocomial cases of L. pneumophila pneumonia were available for typing. PFGE of genomic DNA from the clinical isolates identified six different strains. However, only strain C (16 cases) and strain D (13 cases) caused more than 1 case. Strain C caused clusters of nosocomial infection in 1981, 1986, and 1993 and also caused 4 sporadic cases. Strain D caused a cluster in 1987 and 1988 plus 4 sporadic cases. Of the six strains causing clinical infections, only strains C and D were identified in water samples. PFGE identified three strains in the water supply, of which strains C and D caused clinical disease and also persisted in the water supply during most of the study period. CONCLUSION: Specific strains of L. pneumophila can colonize hospital water supplies and cause nosocomial infections over long periods of time.

National epidemiology of mycoses survey (NEMIS): variations in rates of bloodstream infections due to Candida species in seven surgical intensive care units and six neonatal intensive care units.

Candida species are the fourth most frequent cause of nosocomial bloodstream infections, and 25%-50% occur in critical care units. During an 18-month prospective study period, all patients admitted for > or = 72 hours to the surgical (SICUs) or neonatal intensive care units (NICUs) at each of the participant institutions were followed daily. Among 4,276 patients admitted to the seven SICUs in six centers, there were 42 nosocomial bloodstream infections due to Candida species (9.8/1,000 admissions; 0.99/1,000 patient-days). Of 2,847 babies admitted to the six NICUs, 35 acquired a nosocomial bloodstream infection due to Candida species (12.3/1,000 admissions; 0.64/1,000 patient-days). The following were the most commonly isolated Candida species causing bloodstream infections in the SICU: Candida albicans, 48%; Candida glabrata, 24%; Candida tropicalis, 19%; Candida parapsilosis, 7%; Candida species not otherwise specified, 2%. In the NICU the distribution was as follows: C. albicans, 63%; C. glabrata, 6%; C. parapsilosis, 29%; other, 3%. Of the patients, 30%-50% developed incidental stool colonization, 23% of SICU patients developed incidental urine colonization, and one-third of SICU health care workers' hands were positive for Candida species.

Elucidating the origins of nosocomial infections with Candida albicans by DNA fingerprinting with the complex probe Ca3.

Computer-assisted DNA fingerprinting with the complex probe Ca3 has been used to analyze the relatedness of isolates collected from individuals with nosocomial bloodstream infections (BSIs) and hospital care workers (HCWs) in the surgical and neonatal intensive care units (ICUs) of four hospitals. The results demonstrate that for the majority of patients (90%), isolates collected from commensal sites before and after collection of a BSI isolate were highly similar or identical to the BSI isolate. In addition, the average similarity coefficient for BSI isolates was similar to that for unrelated control isolates. However, the cluster characteristics of BSI isolates in dendrograms generated for each hospital compared to those of unrelated control isolates in a dendrogram demonstrated a higher degree of clustering of the former. In addition, a higher degree of clustering was observed in mixed dendrograms for HCV isolates and BSI isolates for each of the four test hospitals. In most cases, HCW isolates from an ICU were collected after the related BSI isolate, but in a few cases, the reverse was true. Although the results demonstrate that single, dominant endemic strains are not responsible for nosocomial BSIs in neonatal ICUs and surgical ICUs, they suggest that multiple endemic strains may be responsible for a significant number of cases. The results also suggest that cross-contamination occurs between patients and HCWs and between HCWs in the same ICU and in different ICUs. The temporal sequence of isolation also suggests that in the majority of cases HCWs are contaminated by isolates from colonized patients, but in a significant minority, the reverse is true. The results of this study provide the framework for a strategy for more definitive testing of the origins of Candida albicans strains responsible for nosocomial infections.

The epidemiology of bacterial sepsis.

As a result of better understanding of pathogenesis, new definitions of sepsis have been proposed, and the complexity of this syndrome is clearer. Population-based studies of bloodstream infections--what now is called sepsis--have helped us to understand the natural history of this very frequent problem. The mortality and morbidity of each of the systemic inflammatory response syndrome stages have been described; our ability to better understand and predict these stages will help us to make better therapeutic decisions.

The dynamics of disease progression in sepsis: Markov modeling describing the natural history and the likely impact of effective antisepsis agents.

We conducted a 9-month prospective cohort study of 2,527 patients with systemic inflammatory response syndrome in three intensive care units and three general wards in a tertiary health care institution. Markov models were developed to predict the probability of movement to and from more severe stages--sepsis, severe sepsis, or septic shock--at 1, 3, and 7 days. For patients with sepsis, severe sepsis, and septic shock, the probabilities of remaining in the same category after 1 day were .65, .68, and .61, respectively. The probability for progression after 1 day was .09 for sepsis to severe sepsis and .026 for severe sepsis to shock. The probability of patients with sepsis, severe sepsis, and septic shock dying after 1 day was .005, .009, and .079, respectively. The model can be used to predict the reduction in end organ dysfunction and mortality with use of increasingly effective antisepsis agents.

National epidemiology of mycoses survey: a multicenter study of strain variation and antifungal susceptibility among isolates of Candida species.

The National Epidemiology of Mycoses Survey (NEMIS) involves six academic centers studying fungal infections in surgical and neonatal intensive care unit (ICU) patients. We studied variation in species and strain distribution and anti-fungal susceptibility of 408 isolates of Candida spp. Candida spp. were isolated from blood, other normally sterile site cultures, abscesses, wounds, catheters, and tissue biopsies of 141 patients hospitalized in the surgical (107 patients) and neonatal (34 patients) ICUs of medical centers located in Oregon, Iowa, California, Texas, Georgia, and New York. Isolates were also obtained from selected colonized patients (16 patients) and the hands of health care workers (27 individuals). DNA typing was performed using pulsed field gel electrophoresis, and antifungal susceptibility to amphotericin B, 5-fluorocytosine, fluconazole, and itraconazole was determined using National Committee for Clinical Laboratory Standards (NCCLS) methods. Important variation in susceptibility to itraconazole and fluconazole was noted: MICs of itraconazole ranged from 0.25 microgram/mL (MIC90) in Texas to 2.0 micrograms/mL (MIC90) in New York. Similarly, the MIC90 for fluconazole was higher for isolates from New York (64 micrograms/mL) compared to the other sites (8-16 micrograms/mL). In general, DNA typing revealed patient-unique strains; however, there were 13 instances of possible cross-infection noted in 5 of the medical centers. Notably, 9 of the 13 clusters involved species of Candida other than C. albicans. Potential transmission from patient-to-patient (C. albicans, C. glabrata, C. tropicalis, C. parapsilosis) and health care worker-to-patient (C. albicans, C. parapsilosis, C. krusei) was noted in both surgical ICU and neonatal ICU settings. These data provide further insight into the epidemiology of nosocomial candidiasis in the ICU setting.