H Díaz-Ponce’s research while affiliated with Mexican Institute of Social Security and other places

The diagnosis of candidemia by blood culture has poor sensitivity; therefore, immunossupresed patients and those with risk factors may receive empirical antifungal therapy, wich is potentially toxic. Fluorescent tests have been developed to obtain an early and more sensitive diagnosis than blood culture. The aim of this study was to compare indirect immunofluorescence vs direct calcofluor white fluorescence in buffy coat for candidemia diagnosis. Sensitivity, specificity, predictive values, of positive and negative samples were 60%, 86%, 33%, 95% and 90%, 80%, 35%, 99%, for indirect immunofluorescence and calcofluor white, respectively.

The aim of this study was to evaluate the utility of a volume-modified blood culture system to diagnose bacteremia in newborns and infants. A total of 793 paired blood cultures, obtained from 464 patients (173 newborns and 291 infants), were analyzed. Vacutainer tubes containing 18 ml supplemented peptone broth sodium-polyanethol-sulfonate were used as the gold standard, in comparison with a blood micro-culture system containing 1.8 ml of the broth. Prior to antibiotic treatment, 2.2 ml of blood was obtained from each patient; 0.2 ml was inoculated in a blood micro-culture tube and 2 ml in a routine tube. Sensitivity, specificity and predictive values were calculated. Microorganisms were isolated in 153 standard blood culture tubes and 151 blood micro-culture tubes. The sensitivity of the blood micro-culture system was 95%, specificity 99% and positive and negative predictive values 96% and 99% respectively. The sensitivity and specificity of blood micro-culture in neonates and infants is high. We recommend that this system be used for the diagnosis of bacteremia in newborns and infants in laboratories where manual systems are still in use.

Introduction: The purpose of this study was to identify the species of Enterococcus isolated in pediatric patients and to determine their antimicrobial sensitivity in vitro. Materials and methods. The species were identified through standard techniques. Antimicrobial sensitivity was determined by means of the serial dilution in agar method and the antibiotics were tested in concentrations ranging from 0.5 to 32 mg/L. In the case of gentamicin, a concentration of 2000 mg/L was included in order to detect high resistance. Results. From January 1994 to June 1995, 289 strains of Enterococcus were isolated: 111 from urinecultures, 89 from catheter tips, 40 from secretions, 34 from bloodcultures and 15 from other body fluids. The identified species were: 220 strains (76.1%) of Enterococcus faecalis, 29 strains (10%) of Enterococcus avium, 16 strains (5.5%) of Enterococcus raffinosus, 15 strains (5.2%) of Enterococcus faecium, 5 strains (1.7%) of Enterococcus hirae and 4 strains (1.4%) of Enterococcus malodoratus. The in vitro resistance to the group of aminoglycosides (netilmicin, gentamicin and amikacin) ranged from 70 to 90%; resistance to β-lactamic agents (imipenem, penicillin and ampicillin) ranged from 17 to 33%; resistance to chloramphenicol was of 40%, and to vancomycin of 3.1%. Forty five strains showed high resistance to gentamicin. Conclusions. The most frequently isolated species was Enterococcus faecalis. The in vitro resistance to aminoglycosides was high resistance to vancomycin was low. Of all strains, 15.5% showed high resistance to gentamicin. Enterococcus; antimicrobial resistance; pediatric infections.

In this work we compare the sensitivity, specificity and predictive values of hemagglutination inhibition (HI), immunofluorescent assay (IFA), biotin-streptavidin immunofluorescent assay (B/SA-IFA), enzyme-linked immunosorbent assay (EIA) and plaque neutralization test (PN). This study includes serum samples from children taken before and after vaccination, children with clinically diagnosed measles and household contacts. EIA were the most specific and better serological diagnostic test. HI and IFA had high sensitivity but low specificity. An alternative to EIA is B/SAIFA, which is cheaper than EIA and can be used in the study of small outbreaks or in isolated cases.

A randomized clinical trial was performed in children with cancer, fever and neutropenia, to evaluate the efficacy of amikacin once daily versus thrice daily dosing plus carbenicillin in both groups. Fifty patients were included, 25 patients in group A who received amikacin once daily and 25 in group B who received amikacin thrice daily. No intergroup differences were observed, i.e., fever diminished in a median of 6 days (2-8 days) vs. 7 days (3-12 days) in groups A and B respectively (p = 0.37);clinical improvement was observed in a median of 6 days (3-10 days) vs 7 days (2-14 days) (p = 0.68). One patient in group A and two in B died. The peak levels of amikacin on the 7th day of treatment were 10-60 and 7-25 micrograms/mL in groups A and B respectively, and the serum creatinine levels were 0.3 - 0.7 for group A and 0.2 - 0.8 mg/dL for group B; none of the patients presented a creatinine above 40% of the basal value. Three patients of group A had amikacin levels higher than 40 micrograms/mL without increasing the creatinine levels; our observations do not suggest that toxicity is higher. We conclude that the administration of aminoglycoside once daily seems to be as effective as the traditional dosing.

A randomized clinical trial was performed in children with cancer, fever and neutropenia, to evaluate the efficacy of amikacin once daily versus thrice daily dosing plus carbenicillin in both groups. Fifty patients were included, 25 patients in group A who received amikacin once daily and 25 in group B who received amikacin thrice daily. No intergroup differences were observed, i.e., fever diminished in a median of 6 days (2-8 days) vs. 7 days (3-12 days) in groups A and B respectively (p = 0.37); clinical improvement was observed in a median of 6 days (3-10 days) vs 7 days (2-14 days) (p = 0.68). One patient in group A and two in B died. The peak levels of amikacin on the 7th day of treatment were 10-60 and 7-25 μg/mL in groups A and B respectively, and the serum creatinine levels were 0.3-0.7 for group A and 0.2-0.8 mg/dL for group B; none of the patients presented a creatinine above 40% of the basal value. Three patients of group A had amikacin levels higher than 40 μg/mL without increasing the creatinine levels; our observations do not suggest that toxicity is higher. We conclude that the administration of aminoglycoside once daily seems to be as effective as the traditional dosing.

Visceral leishmaniasis is a rare parasitosis in our country; in a 30 year period only exists the report of five cases, three in the state of Puebla and two in the state of Guerrero. Now it has been identified another two cases in the state of Chiapas. In these patients the common presentation of the disease were fever, hepatosplenomegaly, hypergammaglobulinemia and pancytopenia. The parasite can be found in liver, spleen, lymph nodes and bone marrow macrophages. A definitive diagnosis depends on the demonstration of the parasite in tissue; spleen biopsy is the most useful because it is positive in 98% of the cases, in other tissues the amastigotes are seen in 50-80% of the cases. Negative PAS-stained smears maintains the diagnosis until another more specific method as electronic microscopy or culture is available. Pentavalent antimonial compounds are the drugs of choice and as an alternative or in case of failure amphotericin B can be used.

We report a case of a female infant, from Acapulco Guerrero, Mexico. She had been sick for 45 days, with diarrhea and general malaise, fever during the last 20 days; at physical examination she was pale, with abdominal distention and hepatosplenomegaly. She had leukopenia, thrombocytopenia and anemia. The microscopic findings in the bone marrow sample were intracytoplasmic and extracellular bodies. Both bone marrow and blood cultures were positive for Histoplasma capsulatum. Seventy three pediatric cases of diseminated histoplasmosis have been described in the medical literature since 1934 to 1988. It is know that only about 1% of the persons that become infected will develop a diseminated disease.