Frontiers in Internal Medicine.

Clinical research in Internal Medicine has provided many scientific advances during the past few years. However, the newly generated information overrides the time available to read all of the medical literature regarding advances in Internal Medicine. The goal of this review is to summarize some of the most relevant improvements in clinical practice published over the last few years. From Cardiology to Pulmonology, the authors of this review expose in a succinct way what they and many of their peers consider to be the most transcendental information gathered from thousands of publications. The authors of this review article have attempted to avoid sensationalism by including facts instead of just simply optimistic preliminary findings that can mislead clinicians' decision making. The review is focused on information obtained through well-designed, prospective clinical trials and cohorts where the effectiveness of medical interventions and diagnostic procedures were tested.

Comparative tuberculin reactivity to two protein derivatives.

OBJECTIVE: To evaluate the tuberculin reactivity among medical students and the utility of RT-23 (2 tuberculin unit [TU] purified protein derivative [PPD]) produced in Mexico. DESIGN: A blind and comparative study was conducted in a school of medicine using simultaneously RT-23 and an American product (5 TU PPD) randomly assigned to each forearm and read 48 hours later. Ninety eight volunteers were included, 69 from the first year and 29 from the fifth year as medical students. RESULTS: Using 5 TU PPD, 16% of first year students and 41% of fifth grade students were positive (induration > or = 10 mm). The RT-23 worked well and showed a sensitivity of 87% and a specificity of 92%. There was a large difference in the positivity of fifth versus first year students (x2 = 6.00, P = 0.014) with an estimated annual conversion of 5.1%. The high tuberculin conversion rate urges the need to establish preventive and early diagnosis programs for tuberculosis. The utility of RT-23 was found to be comparable to 5 TU PPD in our population.

[Unjustified disposal of transfusion blood because of antibodies against brucella]. / Desecho injustificado de sangre de transfusión por anticuerpos contra Brucella.

OBJECTIVES: To compare the slide microagglutination (SMA) test vs a gold standard test (tube agglutination test: SAT) for the detection of Brucella antibodies in order to evaluate the usefulness of SMA to discard transfusion blood units. DESIGN: Prospective, comparative, cross sectional survey. SETTING: City of Leon, State of Guanajuato, an endemic zone of brucellosis. SAMPLES: 48 sera from blood units discarded for transfusion by three blood banks due to Brucella antibodies detected by SMA and 48 controls of accepted units. METHODS: Determination of Brucella antibodies with the SMA and SAT tests. RESULTS: The 48 control samples were negative with both tests; of the 48 discarded samples, in only seven sera we confirmed a titer > or = 1:80 by SAT; thus, 41 blood units (85%) may have been improperly rejected because the only test used by the blood banks was the SMA. In our hands, the SMA showed a sensitivity and negative predictive value of 100%, a specificity of 81%, and positive predictive value of 29%. CONCLUSIONS: There was a high proportion of improper rejection of blood units for transfusion; Brucella antibodies at any titer detected by SMA should be followed by SAT testing.

Pediatric primary gram-negative nosocomial bacteremia: a possible relationship with infusate contamination.

OBJECTIVE: To evaluate the potential contribution of "extrinsic" contamination of intravenous fluids in hospital bacteremia and infection. DESIGN: Prospective cross-sectional survey of infusate contamination, December 1992 to December 1993. SETTING: A pediatric department (1,500 admissions per year) in a general, urban teaching hospital, serving low-income patients. SAMPLES AND PATIENTS: Infusate samples (0.5 to 1.0 mL) from the injection port used by the staff were taken for cultures from all febrile or septic patients in hospital wards. At least four samples were taken each day; if no febrile or septic patients were available, other patients were sampled at convenience. RESULTS: A 6.8% positive culture rate (87 contaminates in 1,277 infusates) was obtained, without significant differences among the wards. Gram-negative organisms were recovered from 56 samples (62.9%), mainly of the tribe Klebsielleae (56.1%). Coagulase-negative staphylococci were isolated in 30 samples (33.7%). There was no significant difference between the febrile-septic group and the asymptomatic group in the rate of infusate contamination (P = .59). In eight patients, the same organisms were recovered from infusate and blood culture. The overall bacteremia rate was 2.5 per 100 discharges. CONCLUSIONS: Compared to previous reports, higher infusate contamination rates and different organisms (mainly gram-negative) were observed. In hospitals of underdeveloped countries, nosocomial infection control frequently is disregarded. Infusate contamination may be common and could lead to gram-negative bacteremia. In such settings, it seems advisable to perform surveillance studies to identify infusate contamination, because a single infusate contamination could be a signal for an epidemic.

[Pediatric nosocomial bacteremia. Potential usefulness of culturing infusion liquids]. / Bacteriemia nosocomial pediátrica. Utilidad potencial del cultivo de los líquidos de infusión.

Hospital-acquired bacteremia is a common cause of morbidity and mortality, mainly in pediatric units. In a 25 month retrospective study, we analyzed the blood cultures from the Hospital General Regional of the city of Leon, Guanajuato State, Mexico, in order to establish the causal agents of nosocomial bacteremia and infer some associations with contaminated intravenous infusion fluids. In addition we performed a two month study to culture the flasks and intravenous tubing used in our infusions. Five hundred and fifty one blood cultures drawn from August 1990 to September 1992 were analyzed. A total of 135 (24.5%) were positive, most of them (51.8%) with strains of the Klebsielleae tribe (SKT) (Klebsiella, Enterobacter, Serratia). The global incidence of bacteremia in the two year period was 4.3%. In the infusion study, 230 intravenous fluids were cultured, with 68 isolates (30%) most from the SKT tribe. A final consideration is made on the role that inadequate management of intravenous liquids could play in the development of endemic and epidemic nosocomial bacteremia in our hospital, and the eventual utility of making cultures of the i.v. liquids.

[Surveillance of therapy with aminoglycosides at a specialized hospital]. / Vigilancia de terapia con aminoglucósidos en un hospital de especialidades.

Aminoglycosides (AG) are excellent antibiotics against gram-negative bacilli infections, but their use implies potential ototoxicity and nephrotoxicity if an excessive dosage is prescribed. In this study we evaluated 105 episodes of AG treatment in 104 patients hospitalized in a specialty hospital in the city of Leon, Mexico. In each case a basal serum creatinine, weight and age were recorded. A single serum AG assay per episode of treatment was done. Either amikacin or gentamicin were one the AG prescribed. Prior to AG administration only 54 treatment episodes (51%) had a before treatment creatinine assay. The initial creatinine clearance showed normal values in 43% (23/54 episodes) and it was altered (below 80 mL/min) in 31 (57%) of the episodes. In the 31 cases with an altered renal function only 15 (48%) underwent dosage adjustment. In summary the AG were prescribed in excess in 54% (29/54) of the episodes. The serum AG levels within toxic range were observed in 11 episodes. These results suggest that in our hospital AG treatment is not adequately done and monitored.

[The seroepidemiology of rubella in a female population of reproductive age in León, Guanajuato]. / Seroepidemiología de la rubéola en una población femenina en edad fértil de León, Guanajuato.

In order to assess the seroepidemiology of protective antibodies against rubella among women from León, Guanajuato, Mexico, a prospective study was done. The sample consisted in 176 serum samples from urban and rural women at reproductive age, drawn from June 1990 to June 1991. Samples were tested by the classic hemagglutination inhibition method, titers of 1:8 or higher were considered as positive. Global positivity was 71 per cent (125 sera). Seropositivity did not increase with women's age; the lowest values were seen at the rural zones (58.9%). This survey showed a lower seropositivity than the previously reported in Mexico, and confirms data from new official studies. With this information authors suggest that the utility and viability of a national vaccination program should be reviewed and propose that it could be risky that individual clinicians to recommend children vaccination because the lack of coordination could increase adult cases of rubella.