[Drug resistance of Mycobacterium tuberculosis in Orizaba, Veracruz. Implications for the tuberculosis prevention and control program]. / Resistencia de Mycobacterium tuberculosis a los antimicrobianos en Orizaba, Veracruz. Implicaciones para el Programa de Prevención y Control de la Tuberculosis.

BACKGROUND: Tuberculosis, declared a global emergency by the World Health Organization, continues to be an important public health problem in Mexico, included in the first twenty causes of death. OBJECTIVE: To know the impact of drug resistance of Mycobacterium tuberculosis on treatment outcome, need of re-treatment and mortality in a cohort of patients with pulmonary tuberculosis receiving directly observed therapy, short course (DOTS). METHODS: We conducted a population-based study in a suburban region in Southern Mexico. People who had been coughing for more than two weeks underwent sputum acid-fast bacilli smear. Patients with a positive smear were recruited and underwent clinical exam, chest X-ray, HIV testing, and sputum cultures. Identification, drug susceptibility testing and restriction fragment length polymorphism analysis (RFLP) were performed in all isolates. Patients were followed every 12 months for new episodes of tuberculosis and vital status. Patients were referred for clinical care to the local program of tuberculosis. Deaths were corroborated with death certificates. Informed consent was obtained from participants. RESULTS: Between March 1995 and February 1999, tuberculosis was diagnosed in 371 patients who were followed for an average of 32 months. M. tuberculosis was cultured from 316 patients; resistance to any drug occurred in 25.0% of isolates (primary 18.8%, acquired 49.2%); only to isoniazid in 6.8% (primary 7.3%, acquired 4.8%); to isoniazid and rifampin in 6.2% (primary 1.6%, acquired 23.8%). Patients with drug resistance had a higher probability of treatment failure (OR = 16.9, CI 95% 4.5-63.0) and patients with MDR strains had a higher probability of need of re-treatment (RR = 24.4, CI 95% 8.8-67.6), and of death (RR = 4.0, CI 95% 1.5-10.7). Additional variables were found to be associated with subsequent episodes of disease and mortality: Cocaine use, chronic disease, type of radiological lesions, HIV co-infection, non-compliance and treatment delay, as well as RFLP clustering. CONCLUSIONS: In this study, we observed that drug resistance showed a severe impact on the outcome and survival; drug-resistance was the most significant factor for these negative outcomes; DOTS may not be sufficient in areas where drug resistance is considerable, and patient follow-up for longer periods of time, as compared to evaluation at the end of treatment, provides additional information which is useful for prevention and control programs.

Factors associated with tuberculin reactivity in two general hospitals in Mexico.

OBJECTIVE: To identify risk factors associated with tuberculin reactivity in healthcare workers (HCWs). DESIGN: Cross-sectional survey of tuberculin reactivity (2 TU of purified protein derivative (PPD) RT23, using the Mantoux two-step test). SETTING: Two general hospitals located in a region with a high prevalence of tuberculosis and high bacille Calmette-Guerin (BCG) coverage. PARTICIPANTS: Volunteer sample of HCWs. RESULTS: 605 HCWs were recruited: 71.2% female; mean age, 36.4 (standard deviation [SD], 8.2) years; 48.9% nurses, 10.4% physicians, 26.8% administrative personnel; mean time of employment, 10.9 (SD, 6.7) years. PPD reactivity (> or =10 mm) was found in 390 (64.5%). Multivariate analysis revealed an association of tuberculin reactivity with occupational exposure in the hospital: participation in autopsies (odds ratio [OR], 9.3; 95% confidence interval [CI95], 2.1-40.5; P=.003.), more than 1 year of employment (OR, 2.4; CI95, 1.1-5.0; P=.02), work in the emergency or radiology departments (OR, 2.0; CI95, 1.03-3.81; P=.04), being physicians or nurses (OR, 1.5; CI95, 1.04-2.11; P=.03), age (OR, 1.04; CI95, 1.02-1.07 per year of age; P<.001), and BCG scar (OR, 2.1; CI95, 1.2-3.4; P=.005). CONCLUSIONS: Although the studied population has a high baseline prevalence of tuberculosis infection and high coverage of BCG vaccination, nosocomial risk factors associated with PPD reactivity were identified as professional risks; strict early preventive measures must be implemented accordingly.

[The ABCs on anthrax for health personnel]. / El A, B, C, sobre ántrax, para personal de salud.

The purpose of this series of articles is to present to health personnel an updated summary on bioterrorism associated agents. In this first article an updated summary on anthrax is presented. Emphasis has been placed on the characteristics of cases which occurred during October in the United States of America and on the experience of governmental agencies of that country to face the emergency. Measures implemented in Mexico are described as well. The authors are convinced that the best arm against terror is timely and updated information.

Underestimation of Mycobacterium tuberculosis infection in HIV-infected subjects using reactivity to tuberculin and anergy panel.

BACKGROUND: This study aimed to evaluate purified protein derivative (PPD) reactivity and its interrelationship with anergy panel and CD4+ lymphocytes in HIV-infected subjects as compared to PPD reactivity in HIV-uninfected individuals in a tuberculosis endemic and high Bacillus Calmette-Guérin (BCG) coverage environment. METHODS: Clients of four Mexico City HIV detection centres were screened for HIV-1 antibodies (ELISA or haemagglutination, Western Blot); reactivity to PPD (Mantoux PPD, 5TU RT-23), Candida (1:1000, 0.1 ml), and tetanus toxoid (10Lf, 0.1 ml); and CD4+ T cells. Active tuberculosis was excluded. Informed consent was obtained. RESULTS: From 5130 clients 1168 subjects were enrolled; of these 801 (68.6%) were HIV positive. Reactivity to PPD among HIV-positive subjects was found in 174 (22%), 261 (32.6%), and 296 (37%), at PPD cutoff levels of > or =10 mm, > or =5 mm, and > or =2 mm as compared to 224 (61%) of 367 HIV-negative individuals' reactors to PPD (> or =10 mm) (P < 0.001). After exclusion of anergic individuals using two cutoff levels for cutaneous allergens (< or =2 mm and < or =5 mm), PPD reactivity between HIV-infected and uninfected individuals continued to be significantly different. Only HIV-infected individuals with CD4+ T cells > or =500 cells/mm3 had similar reactivity to PPD as HIV-uninfected individuals. Variables associated with PPD reactivity were CD4+ T cell counts, BCG scar, HIV infection and age. CONCLUSIONS: PPD reactivity was useful to diagnose tuberculosis infection only among HIV-infected individuals with CD4+ counts > or =500 cells/mm3. Among individuals with lower counts, lowering cutoff levels or using anergy panel did not permit comparable reactivity as that observed among HIV-uninfected individuals.

Clinical consequences and transmissibility of drug-resistant tuberculosis in southern Mexico.

BACKGROUND: Consequences of drug-resistant tuberculosis (TB) in developing countries using directly observed treatment, short-course (DOTS), are not well defined. OBJECTIVE: To determine the impact of drug resistance on clinical outcome and transmission of TB under programmatic conditions. PATIENTS AND METHODS: A prospective cohort and molecular epidemiologic study was conducted in southern Mexico. Between March 1995 and February 1998 all patients with persistent cough whose sputa had acid-fast bacilli (AFB) underwent clinical and mycobacteriologic evaluation (species identification, drug susceptibility testing, and IS6110-based genotyping). Treatment was provided in accordance with Mexico's National Tuberculosis Program. Clinical and microbiologic outcomes and molecular epidemiologically defined transmission were measured. RESULTS: Mycobacterium tuberculosis was isolated from 238 of the 284 AFB smear-positive persons. The overall rate of resistance was 28.4% (new, 20.7%; retreated, 54.7%), and 10.8% (new, 3.3%; retreated, 35.8%) had multi-drug-resistant TB (ie, resistance to isoniazid and rifampin). After treatment, 75% (new, 81.0%; retreated, 52.8%) were cured, 8% (new, 7.8%; retreated, 7.5%) abandoned therapy, 9% (new, 3.9%; retreated, 28.3%) had treatment failure, and 4% (new, 3.3%; retreated, 7.5%) died. Another 2% of patients relapsed, and 9% died during a median of 24.4 months of follow-up. Drug-resistance was a strong independent risk factor for treatment failure. Being infected with multi-drug-resistant TB was the only factor associated with a decreased likelihood of being in a restriction fragment length polymorphism cluster. CONCLUSIONS: Despite the use of DOTS, patients with drug-resistant TB had a dramatically increased probability of treatment failure and death. Although multi-drug-resistant TB may have a decreased propensity to spread and cause disease, it has a profoundly negative impact on TB control.

Mycobacterium tuberculosis drug resistance in a suburban community in southern Mexico.

OBJECTIVE: To determine the impact of drug resistance (DR) on the clinical outcome and transmission of tuberculosis under programmatic conditions. METHODS: Prospective cohort and molecular epidemiologic study in the Orizaba Health Jurisdiction of Mexico. Between March 1995 and July 1999, chronic coughers with positive acid-fast bacilli (AFB) detected in sputum smear underwent clinical and mycobacteriologic evaluation (species identification, drug susceptibility testing and IS6110-based genotyping). Treatment was provided in accordance with official norms. RESULTS: Mycobacterium tuberculosis was isolated from 326/387 AFB-positive cases. The rate of DR was 24.2% and that of multidrug resistance (MDR, defined as resistance to both isoniazid and rifampin at least) was 7.7%; 78% were cured, 8% abandoned treatment, 6% failed treatment, and 5% died. An additional 13.5% received retreatment and 8.9% died during a median 28.6 months of follow up. Factors associated with DR by multivariate analysis were chronicity of tuberculosis (OR 4.8, 95%CI 2.7-8.4, P < 0.001), age >40 years (OR 1.9, 95%CI 1.1-3.2, P = 0.02) and indigenous origin (OR 0.3, 95%CI 0.13-0.75, P = 0.01). Cox-adjusted relative risks showed that MDR (RR 2.5, 95%CI 1.02-6.16, P = 0.04), HIV infection (RR 31.3, 95%CI 11.6-84.8, P < 0.001), and chronicity of tuberculosis (RR 2.1, 95%CI 1.0-4.4, P = 0.06) were associated with mortality, controlling for age. Predictors of retreatment were DR (not including MDR) (RR 2.2 95%CI 0.89-5.31, P < 0.087), MDR (RR 12.6, 95%CI 5.46-28.88, P < 0.001), and living in a household with an earthen floor (RR 2.8, 95%CI 1.27-6.13, P = 0.011). Being infected with MDR-TB was the only factor associated with a decreased likelihood of being in an RFLP cluster (OR 0.31, 95%CI 0.12-0.81, P = 0.02). CONCLUSIONS: Although MDR-TB may have a decreased propensity to spread and cause disease, it has a profoundly negative impact on tuberculosis control.

Prevalence and risk of cysticercosis and taeniasis in an urban population of soldiers and their relatives.

To determine markers of Taenia solium transmission and risk factors in an urban community, we studied 1,000 soldiers from a military camp in Mexico City and their relatives. Serum samples were used to detect antigens and antibodies and fecal specimens were examined for Taenia coproantigens and helminth eggs. Prevalences of 12.2% and 5.8% for cysticercosis were found among soldiers and their relatives, respectively. Taeniasis was found in 0.5% and none of the groups, respectively. Relatives of soldiers positive for cysticercosis and taeniasis markers ate more pork from street stores than restaurants or markets compared with relatives of soldiers without these indicators of infection. Also, 12.0% of the relatives of positive soldiers had a history of expelling tapeworm proglottids in the feces in contrast to 3.7% of the family members of the control group. Prevalence values and risk factors in this urban population are similar to those of previous studies performed in rural populations.

Tuberculosis epidemiology and control in Veracruz, Mexico.

BACKGROUND: Tuberculosis (TB) rates remain high in regions of Southern Mexico despite the existence of a National Tuberculosis Program. Understanding TB epidemiology in such settings would assist in the design of improved TB control and highlight the challenges confronting TB control in developing countries. METHODS: We conducted a retrospective review of treatment control cards from 1991 to 1994 in five municipalities in a semiurban region of Southern Mexico. RESULTS: The relatively high rate of TB observed, 42.6 per 100,000 inhabitants, did not change significantly during the study period. Cure rates among new cases were 79% and significantly lower among retreatment cases (62%). Directly observed therapy (DOT) was administered to 84% of patients. Approximately one-half of the retreatment cases who were not cured were compliant with therapy, suggesting that drug resistance contributed to these poor results. Of particular concern was a core group of 16 patients who had received at least three treatments. CONCLUSIONS: This region of Mexico has persistently high TB rates despite a DOT-based TB control programme which achieves an overall cure rate of 77%. There exist many retreatment cases for whom cure rates are significantly lower. These cases may serve as a core group for the dissemination of drug resistant TB. The control programme is being reinforced by a nominal register of patients, decreasing administrative barriers for drug supply to individual patients and the availability of mycobacteria cultures. In addition to these measures, in regions which are approaching the levels of efficacy recommended by the WHO it may be appropriate to consider focusing efforts on the identification and treatment of chronic cases.

[Efficacy and efficiency of antitubercular treatment in health jurisdictions of Morelos]. / Eficacia y eficiencia del tratamiento antituberculoso en jurisdicciones sanitarias de Morelos.

OBJECTIVE: To evaluate the efficacy and efficiency of tuberculosis treatment administered by the Secretaría de Salud (SSA) in the sanitary jurisdictions of Cuernavaca and Cuautla, Morelos, for the 1992-1996 period by retrospectively reviewing tuberculosis treatment control cards. MATERIAL AND METHODS: Official Norm for Tuberculosis Prevention and Control in Primary Care Units outcome definitions were used. Data was collected on standardized forms and analyzed with SAS and Epi Info programs; 149 primary care units and 4 hospitals in the study area were visited. RESULTS: There were found 288 patients cards, of which 260 were new cases. These patients received 311 treatments of which 85% were directly observed. Reviewed cards represented 60% of SSA notified cases for this period. There were analyzed 246 treatments of which 32% were bacteriological cures, 26% probable cures, 18% dropouts, 1% failures and 3% deaths. In 20% of treatments the outcome was unknown. Cure rate was better in new cases (61%) than in retreatments (38%), p < 0.01. Efficacy of treatment was 71% and efficiency 58%. Patients receiving retreatment abandoned it more frequently (32%) than new cases (16%), p < 0.01. A statistically significant association was found between abandoned treatment and being retreated (OR = 3.3, CI 95% 1.3-8.5, p = 0.01) or belonging to a lower socioeconomic level (OR = 2.3, CI 95% 1.0-4.9, p = 0.04). In the 34 retreatment programs, 22 were initiated after abandonment, failure or relapse. CONCLUSIONS: Proportion of cure rate (58%) compares unfavorably with WHO recommendations (85%). Implications of a high dropout rate and probability of circulation of resistant strains of M tuberculosis are discussed. Creative strategies to reinforce patient compliance which take into account the patient and not only the health services, extension of cultures to known M. tuberculosis drug resistance and evaluation of modifications to drug regimens are proposed. Review of treatment control cards is a useful tool for program evaluation.

Epidemiology of AIDS and tuberculosis.

This article reviews literature on the epidemiology, pathogenicity, and control of HIV and Mycobacterium tuberculosis coinfection. Regarding pathogenicity, immune system deterioration makes HIV-infected people more likely to develop active tuberculosis on primary or secondary exposure to the bacillus or to suffer reactivation of latent infections, and to experience considerably higher rates of extrapulmonary manifestations, relapses, and death. Regarding epidemiology, as of 1990 there were an estimated 3 million people coinfected with HIV and M. tuberculosis, with some 300,000 active tuberculosis cases and 120,000-150,000 tuberculosis deaths occurring annually among those coinfected. Over 500,000 coinfected people are thought to reside in the Americas, over 400,000 of them in Latin America. In general, the impact of coinfection is evident. Relatively high and increasing prevalences of HIV infection have been detected among tuberculosis patients around the world, and tuberculosis has become a frequent complication of AIDS cases. Moreover, there is no longer any doubt that coinfection obstructs tuberculosis prevention and control. Among other things, it affects BCG vaccination policies, suggests the need to administer preventive chemoprophylaxis to HIV-infected individuals at high risk of harboring or contracting tuberculosis infections, and complicates both detection and treatment of active tuberculosis cases. The recent proliferation of M. tuberculosis strains resistant to multiple drugs, most notably in the United States, compounds the problem. Tuberculosis prevention and control are still technically and economically feasible. However, more must be done to establish surveillance programs with laboratory support. More research is needed to determine what case prevention measures are best-suited to current circumstances and the HIV/AIDS presence. More effective preventive treatment regimens that are well tolerated, well complied with, and do not pose the risk of multiresistance need to be devised. More health workers need to be trained to suspect tuberculosis and to conduct timely and appropriate tests confirming this diagnosis. And finally, more must be done to standardize the types and durations of the various curative treatment regimens employed.

[Epidemiology and etiology of infectious diarrheas. The case of Mexico]. / Epidemiología y etiología de las diarreas infecciosas. El caso de México.

Gastrointestinal infections represent a health problem. It is estimated that 1647 million cases of diarrhea and 3.2 million deaths due to this cause occur among children less than five years of age per year. Those belonging to this age group have 15 times more risk of dying because of diarrhea. Cases of liquid acute diarrhea with blood represent 80% of cases, diarrhea with blood represent 10%. Most frequent causes of liquid diarrhea are enterotoxigenic Escherichia coli and rotaviruses and most frequent causes of bloody diarrhea are Shigella, E. coli (EHEC and EPEC). Campylobacter jejuni and Entamoeba histolytica. Annually 15,000 cases of typhoid fever are reported that continue being a public health problem. A negative correlation has been observed between the use of oral rehydration and infant mortality due to diarrhea. After prevention and control measures for cholera, a decrease in morbidity and mortality due to diarrhea has been observed. However, to reduce mortality due to this cause, it is necessary to treat the cases of acute dysentery and persistent diarrhea as well as to increase coverage of health care, to standardize the studies of etiology of diarrhea in Mexico, to establish surveillance centers for the study of diarrhea that give information on the distribution, frequency and trends of microbial agents and to achieve standardized microbiological and parasitological studies of etiology of diarrhea that support public health interventions as vaccination and selective administration of antibiotics.

[Education of Mexican health personnel on AIDS]. / Educación del personal de salud de México sobre el SIDA.

We describe the epidemiology of AIDS as it pertains to health workers in Mexico. Of the 12,151 cases notified in adults up until 1993, 2.9% occurred among such workers. Two cases of occupational transmission have been documented. Seroprevalence surveys have shown an infection rate of less than 0.1%. Nonetheless, the frequency with which hepatitis B viral markers are present (11.8% of anti-HBs antibody carriers and 2% of anti-HBsAg antibody carriers) points to the fact that mechanisms for the transmission of both types of viruses are at work. Surveys conducted among health workers to explore their knowledge and attitudes on the subject of AIDS indicate that they share many false notions about the disease and that they stigmatize its victims. Educational campaigns have improved knowledge about the illness but have not modified people's attitudes significantly. Holding workshops has proved to be the most useful strategy for attitude modification. We describe a few strategies that may be useful for changing negative attitudes among health personnel. When calculating the frequency with which biosafety measures are implemented, it has been noted that their application is erratic. Epidemiologic studies have confirmed the existence of an association between the time of occupational exposure and the presence of hepatitis B viral markers. Many people reject adopting certain measures, such as anti-hepatitis vaccination. Finally, we analyze the need for continuous training and supplies if increased biosafety measures are to be adopted.

[Evaluation of a program for monitoring of nosocomial infections]. / Validación de un programa de vigilancia de infecciones nosocomiales.

The results of two nosocomial infection surveillance programs are presented. They were conducted sequentially during a period of eight months, in a general hospital in Mexico City. The purpose of the study was to evaluate the results of a previously installed program based on the investigation of the incidence of episodes of nosocomial infections through the results of the investigation of the prevalence of these episodes. The observed prevalence and incidence rates and the calculated incidence rate were 23 percent, (127 episodes in 547 patients); 4.52 percent (134 episodes in 2,963 discharges) and 4 percent. The commonest problems detected by both studies were surgical wound and urinary tract infections. Pseudomonas and coagulase negative Staphylococcus were isolated most frequently during each period. It is concluded the system based on the investigation of the incidence of nosocomial infections works adequately in this hospital. The advantages of the design of the prevalence system are discussed, since it permitted the analysis of the infection risk associated to different invasive procedures. The odds ratio for acquiring respiratory infection was 152 (C.I. 95%: 31,732) in patients that underwent tracheostomy, 20 (C.I. 95%: 4 90) in patients with respirator, 34 (C.I. 95%: 8,142) in patients with endotracheal tube and 33 (C.I. 95%: 8,137) in patients with nasogastric tubes.