Erythromycin-resistant Streptococcus pyogenes in Argentina

Erythromycin (ERY) resistance in Streptococcus pyogenes has recently emerged as a problem of growing concern all through the world. We are presenting the comparison of results of the continuous surveillance of erythromycin resistance in S. pyogenes performed since 1989 in the Hospital de Pediatría J.P.Garrahan of Buenos Aires City, with independently observed rates in other five centers of Buenos Aires and seven centers of six other Argentinian cities, obtained between 1999 and 2001. A significant increase of erythromycin resistance was observed among S. pyogenes isolated in the Hospital Garrahan (6.6% in 1998-1999 to 9.9% in 2000). Similar trends were also detected in other centers of other Argentinian cities when recent data were compared to results of a multicenter study performed in 1995. However, lower rates of resistance were recorded in Mendoza, Cipolletti and Neuquén in comparison with data of 1995, 1998 and 1998 respectively. The reason of such decreasing resistance rates deserves to be investigated. The average of ERY-resistance rates obtained in the surveyed centers was 6.7% (range 0.5-14.1%). Control of antimicrobial use should be performed to warrant the future effectiveness of macrolide antibiotics regarding the positive association between use and resistance. These results also suggest that susceptibility tests for macrolides should be performed whenever S. pyogenes is isolated in Argentina.

La resistencia a la eritromicina en Streptococcus pyogenes ha emergido en los últimos tiempos como un problema creciente en todo el mundo. En este trabajo se presenta la comparación de los resultados de la vigilancia continua de la resistencia a la eritromicina que se viene realizando en el Hospital de Pediatría J.P.Garrahan de Buenos Aires desde 1989, con resultados independientes de otros cinco centros de la ciudad de Buenos Aires y siete de otras seis ciudades argentinas, obtenidos entre 1999 y 2001. Se observó un aumento significativo en el Hospital Garrahan (6.6% en1998-1999 a 9.9% en el año 2000) y una tendencia similar en otros centros de diversas ciudades argentinas si secomparan estos datos con los de un estudio multicéntrico realizado en 1995. No obstante, se registraron menoresporcentajes de resistencia en Mendoza, Neuquén y Cipolletti, en relación a lo hallado en 1995, 1998 y 1998respectivamente. La razón de esta disminución merece ser investigada. El porcentaje promedio de resistencia aeritromicina obtenido en los distintos centros participantes de este estudio fue de 6.7% (rango 0.5-14.1%). Debeefectuarse un control en el uso de estos antibióticos para garantizar la efectividad futura de los macrólidos, teniendo en cuenta la asociación estrecha entre uso y resistencia. Estos resultados sugieren que deberían realizarse pruebas de sensibilidad a los macrólidos para todos los aislamientos de S. pyogenes en la Argentina.

Erythromycin-resistant Streptococcus pyogenes in Argentina

Erythromycin (ERY) resistance in Streptococcus pyogenes has recently emerged as a problem of growing concern all through the world. We are presenting the comparison of results of the continuous surveillance of erythromycin resistance in S. pyogenes performed since 1989 in the Hospital de Pediatría J.P.Garrahan of Buenos Aires City, with independently observed rates in other five centers of Buenos Aires and seven centers of six other Argentinian cities, obtained between 1999 and 2001. A significant increase of erythromycin resistance was observed among S. pyogenes isolated in the Hospital Garrahan (6.6% in 1998-1999 to 9.9% in 2000). Similar trends were also detected in other centers of other Argentinian cities when recent data were compared to results of a multicenter study performed in 1995. However, lower rates of resistance were recorded in Mendoza, Cipolletti and Neuquén in comparison with data of 1995, 1998 and 1998 respectively. The reason of such decreasing resistance rates deserves to be investigated. The average of ERY-resistance rates obtained in the surveyed centers was 6.7% (range 0.5-14.1%). Control of antimicrobial use should be performed to warrant the future effectiveness of macrolide antibiotics regarding the positive association between use and resistance. These results also suggest that susceptibility tests for macrolides should be performed whenever S. pyogenes is isolated in Argentina.(AU)

La resistencia a la eritromicina en Streptococcus pyogenes ha emergido en los últimos tiempos como un problema creciente en todo el mundo. En este trabajo se presenta la comparación de los resultados de la vigilancia continua de la resistencia a la eritromicina que se viene realizando en el Hospital de Pediatría J.P.Garrahan de Buenos Aires desde 1989, con resultados independientes de otros cinco centros de la ciudad de Buenos Aires y siete de otras seis ciudades argentinas, obtenidos entre 1999 y 2001. Se observó un aumento significativo en el Hospital Garrahan (6.6% en1998-1999 a 9.9% en el año 2000) y una tendencia similar en otros centros de diversas ciudades argentinas si secomparan estos datos con los de un estudio multicéntrico realizado en 1995. No obstante, se registraron menoresporcentajes de resistencia en Mendoza, Neuquén y Cipolletti, en relación a lo hallado en 1995, 1998 y 1998respectivamente. La razón de esta disminución merece ser investigada. El porcentaje promedio de resistencia aeritromicina obtenido en los distintos centros participantes de este estudio fue de 6.7% (rango 0.5-14.1%). Debeefectuarse un control en el uso de estos antibióticos para garantizar la efectividad futura de los macrólidos, teniendo en cuenta la asociación estrecha entre uso y resistencia. Estos resultados sugieren que deberían realizarse pruebas de sensibilidad a los macrólidos para todos los aislamientos de S. pyogenes en la Argentina.(AU)

Foveal dysfunction and central visual field loss in glaucoma.

OBJECTIVE: To determine whether foveal function distal to the ganglion cell layer is an independent predictor of central visual field function in glaucoma. SETTING: University affiliated hospital and private practice. PARTICIPANTS: Twenty-seven eyes (27 patients) with normal-pressure glaucoma, 10 eyes (10 patients) with primary open-angle glaucoma, and 47 eyes of 47 matched normal volunteers. INTERVENTION AND MAIN OUTCOME MEASURES: Foveal cone electroretinogram (ERG) amplitude, relative optic cup to disc area and their relations to Humphrey full-threshold 30-2 visual field central 4-point mean total deviation (C4MTD) and pattern deviation (C4MPD). RESULTS: Foveal cone ERG amplitude was subnormal in 14 (37.8%) of the 37 glaucomatous eyes and lower in the glaucoma group compared with normal eyes (P<.01). The C4MTD and C4MPD were lower in glaucomatous eyes with subnormal amplitudes compared with those with normal amplitudes (P<.01 and P<.05, respectively). Amplitude was directly correlated with C4MTD (P<.01) and C4MPD (P<.01). Relative optic cup to disc area was inversely correlated with C4MTD (P<.001) and C4MPD (P<.001). Partial correlation analysis revealed that amplitude and relative optic cup to disc area were independent predictors of C4MTD and C4MPD. CONCLUSION: Foveal function distal to the ganglion cell layer and optic disc cupping independently predict central visual field function in glaucoma.

Pegylated megakaryocyte growth and development factor abrogates the lethal thrombocytopenia associated with carboplatin and irradiation in mice.

Megakaryocyte growth and development factor (MGDF) is a potent inducer of megakaryopoiesis in vitro and thrombopoiesis in vivo. The effects of MGDF appear to be lineage-selective, making this cytokine an ideal candidate for use in alleviating clinically relevant thrombocytopenias. This report describes a murine model of life-threatening thrombocytopenia that results from the combination treatment of carboplatin and sublethal irradiation. Mortality of this regimen is 94% and is associated with widespread internal bleeding. The daily administration of pegylated recombinant human MGDF (PEG-rMGDF) significantly reduced mortality (to < 15%) and ameliorated the depth and duration of thrombocytopenia. The severity of leucopenia and anemia was also reduced, although it was not clear whether these effects were direct. Platelets generated in response to PEG-rMGDF were morphologically indistinguishable from normal platelets. PEG-rMGDF administered in combination with murine granulocyte colony-stimulating factor completely prevented mortality and further reduced leukopenia and thrombocytopenia. These data support the concept that PEG-rMGDF may be useful to treat iatrogenic thrombocytopenias.

Immunological profile changes following perioperative autologous vs. homologous blood transfusion in oncologic patients.

To determine the effect of perioperative blood transfusion on immunological parameters, T cells, T-cell subsets, and concanavalin A-induced suppression were measured in 25 patients with colorectal and breast cancer. During the operation, 15 patients received autologous blood and 10 patients had homologous transfusion. The immunological status was again determined after curative surgery. Before surgery, normal percentage of T lymphocytes, decreased ratios of helper/suppressor cells, and impaired con A-induced suppression were found. Following the operation, the helper and suppressor cell percentages reversed to normal, whereas the con A-induced suppression remained impaired. This change was significantly more pronounced in patients who received autologous blood transfusion than in the other group. Autotransfusion has an impact on immune parameters that might prove less detrimental to the clinical outcome in oncologic surgery than homologous transfusion.

Regulation of nitric oxide synthesis by proinflammatory cytokines in human umbilical vein endothelial cells. Elevations in tetrahydrobiopterin levels enhance endothelial nitric oxide synthase specific activity.

We have examined cytokine regulation of nitric oxide synthase (NOS) in human umbilical vein endothelial cells (HUVEC). 24-h treatment with IFN-gamma (200 U/ml) plus TNF (200 U/ml) or IL-1 beta (5 U/ml) increased NOS activity in HUVEC lysates, measured as conversion of [14C]L-arginine to [14C]L-citrulline. Essentially, all NOS activity in these cells was calcium dependent and membrane associated. Histamine-induced nitric oxide release, measured by chemiluminescence, was greater in cytokine-treated cells than in control cells. Paradoxically, steady-state mRNA levels of endothelial NOS fell by 94 +/- 2.0% after cytokine treatment. Supplementation of HUVEC lysates with exogenous tetrahydrobiopterin (3 microM) greatly increased total NOS activity, and under these assay conditions, cytokine treatment decreased maximal NOS activity. IFN-gamma plus TNF or IL-1 beta increased endogenous tetrahydrobiopterin levels and GTP cyclohydrolase I activity, the rate-limiting enzyme of tetrahydrobiopterin synthesis. Intracellular tetrahydrobiopterin levels were higher in freshly isolated HUVEC than in cultured cells, but were still limiting. We conclude that inflammatory cytokines increase NOS activity in cultured human endothelial cells by increasing tetrahydrobiopterin levels in the face of falling total enzyme; similar regulation appears possible in vivo.

Deletion mutagenesis of rat PC12 tyrosine hydroxylase regulatory and catalytic domains.

The functional organization of rat tyrosine hydroxylase was investigated by deletion mutagenesis of the regulatory and catalytic domains. A series of tyrosine hydroxylase cDNA deletion mutants were amplified by PCR, cloned into the pET3C prokaryotic expression vector, and the mutant proteins were partially purified from E. coli. The results show that the deletion of up to 157 N-terminal amino acids activated the enzyme, but further deletion to position 184 completely destroyed catalytic activity. On the carboxyl end, the removal of 43 amino acids decreased but did not eliminate activity, suggesting that this region may play a different role in the regulation of the enzyme. These findings place the amino end of the catalytic domain between residues 158 and 184 and the carboxyl end at or prior to position 455. Deletions within the first 157 amino acids in the N-terminus caused an increase in hydroxylating activity, a decrease in the apparent Km for tyrosine and phenylalanine substrates, and a substantial increase in the Ki for dopamine inhibition. The results define this region of the N-terminus as the regulatory domain of tyrosine hydroxylase, whose primary functions are to restrict the binding of amino acid substrates and to facilitate catecholamine inhibition. The results also suggest that the well-established role of the regulatory domain in restricting cofactor binding may be secondary to an increase in catecholamine binding, which in turn lowers the affinity for the cofactor. These findings provide new insight into the functional organization and mechanisms of regulation of tyrosine hydroxylase.

Studies on the interaction of a thiol-dependent hydrogen peroxide scavenging enzyme and phenylalanine hydroxylase.

Rat liver phenylalanine hydroxylase is irreversibly inactivated by a H2O2-dependent process. Since H2O2 can be produced by autooxidation of the tetrahydropterin cofactor required for the hydroxylation reaction, in vitro assays are usually carried out in the presence of added catalase. On the basis of a dithiothreitol-dependent protecting assay of phenylalanine hydroxylase, carried out in the absence of catalase, we have isolated an enzyme fraction from neonatal rat livers which has similar properties to the known enzyme, glutathione peroxidase. The developmental time course for phenylalanine hydroxylase in rats has been reported to follow two different patterns. Using the dithiothreitol assay, McGee et al. (1972, Biochem. J. 127, 669-674) have found that newborn rats have low phenylalanine hydroxylase activity which increases to adult levels over several months. On the other hand, using catalase-supplemented assays, others have found that newborn rats have nearly adult levels of phenylalanine hydroxylase activity. The protective effect of glutathione peroxidase on phenylalanine hydroxylase suggests that the developmental time course found by McGee et al. may represent the slow developmental time course previously found for glutathione peroxidase. In addition, feeding rats a selenium-deficient diet, which reduces the hepatic activity of the selenium-containing glutathione peroxidase, results in a concomitant irreversible loss of phenylalanine hydroxylase activity, suggesting that glutathione peroxidase may play a vital role in protecting phenylalanine hydroxylase in vivo from peroxide inactivation.

Nutritional impact of acquired immune deficiency syndrome: a unique counseling opportunity.

The acquired immune deficiency syndrome (AIDS) presents a challenge for dietitians. Changes in the immune system have a potentially detrimental effect on nutritional status as a result of conditions such as anorexia, infection, diarrhea, and drug side effects. Conversely, poor nutrition status may adversely alter the immune systems. Dietary guidelines for the management of these conditions and additional obstacles are discussed. When counseling patients with AIDS, the dietitian needs to be aware of and sensitive to alternative therapies, to evaluate their effectiveness, and to assist in determining their place in the patient's treatment. Psychosocial factors that could influence nutritional status, such as dementia, unemployment, and isolation, must also be taken into consideration. A nutrition program has been established to address the needs of AIDS patients at AIDS Project Los Angeles-Necessities of Life Program (APLA-NOLP), a food distribution center. The goal of the program is to maintain or improve the client's nutritional status by providing education and counseling. The nutrition program has been enthusiastically received, and the outcome of the program on the nutritional status of the participants is currently under study. The dietitian is in a unique position to intervene by providing resource information, food preparation tips, and individualized nutrition plans. It is imperative that the dietitian become familiar with the AIDS disease process and its implications for nutritional status to be considered an expert in the nutrition management of such patients.

Nutritional support for the infant with extrahepatic biliary atresia.

Some infants with biliary atresia obtain dramatic improvement for prolonged periods after the performance of hepatic portoenterostomy. Such infants may have life styles not substantially different from those of normal children. In others, the benefit from this operation, if any, is short lived. These infants are very vulnerable to the debilitating effects of severe, prolonged malabsorption and ultimately require orthotopic liver transplantation to sustain life. The physician caring for infants awaiting liver transplantation can do much, not only to prolong survival but to maintain satisfactory growth and development. The key consideration is to provide adequate nitrogen and nonnitrogen calories, liberally utilizing modern methods of enteral alimentation when necessary. In addition, attention must be directed toward several vitamin and mineral deficiencies, particularly those of the fat-soluble vitamins, that inevitably accompany severe malabsorption in children. Management of extrahepatic biliary atresia in infants is difficult and requires meticulous attention to details. Nevertheless, the long-term cure of this disorder provided by liver transplantation makes their care a rewarding experience.

Orthotopic liver transplantation for type I Crigler-Najjar syndrome.

A neurologically normal 3-year-old girl with Type I Crigler-Najjar syndrome was successfully treated with orthotopic liver transplantation. Preoperative serum bilirubin concentrations as high as 31 mg per dl were not diminished with phenobarbital or phototherapy. Bilirubin fractionation of duodenal bile prior to transplantation revealed 87.1% unconjugated bilirubin and 12.9% monoconjugates as determined by alkaline methanolysis-high-performance liquid chromatography. Postoperatively, the serum bilirubin concentration quickly fell to normal. Uridine diphosphate glucuronyl transferase activity in the recipient liver was not detectable. The gallbladder bile bilirubin concentration of 23.9 mg per dl was less than 15% of previously reported normal values. Since devastating kernicteric brain injury is the invariable outcome of Type I Crigler-Najjar syndrome, liver transplantation should be performed when phototherapy cannot maintain the serum bilirubin concentration at an unequivocally safe level.

Iron deficiency anemia among Jewish and Arab infants at 6 and 12 months of age in Hadera, Israel.

Infants attending six Family Health Centers of the Israel Ministry of Health in various Jewish and Arab localities in the Hadera subdistrict were examined for hemoglobin levels at 6 and 12 months of age. The prevalence of anemia (hemoglobin less than 11 g/dl) among Jewish infants rose from a total of 44.7 to 60% from 6 to 12 months. For the Arab infants, the prevalence of anemia increased from a total of 43.7% at 6 months to 71.0% at 12. The prevalence of severe anemia (less than 10 g/dl) for the Jewish infants rose from 4.5 to 13.1% and for the Arab infants from 7.7 to 19.6%. Of the Jewish infants with a hemoglobin level less than 10 g/dl at 6 months, 50% were still less than 10 g/dl at 12 months. Of the Arab infants less than 10 g/dl at 6 months, 36.4% were still at that level at 12 months. The lack of routine iron supplementation as a preventive procedure and the routine use of cow's milk for infant feeding are the probable causes of this high prevalence of iron deficiency anemia.

Nonlinear elimination and cholerteic effect of valproic acid in the monkey.

Five adult cynomolgus monkeys (Macaca fascicularis) were each given doses of 15 and 150 mg/kg of sodium valproate on separate occasions through indwelling arterial or venous catheters. Timed samples of blood (0-1440 min) and urine were collected for measurement of free and conjugated valproic acid (VPA). In all animals a brief distribution (alpha) phase, complete by 10 to 15 min, was followed by a biphasic decline in concentration of the drug. The times required for the concentration of VPA in blood at 25 min to decline by 50% were 42.4 +/- 2.6 (S.E.) min and 94 +/- 7.5 (S.E.) min at the 15 and 150 mg/kg doses, respectively. The terminal half-lives (T 1/2) were 345 +/- 46 (S.E.) min and 428 +/- 56 (S.E.) min at the low and high dose, respectively. In contrast to our earlier studies in the rat, surgical exteriorization of the bile did not alter the elimination profile of VPA from the blood of the monkey. Only 3 to 7% of the administered dose of the drug appeared as conjugated VPA in the bile (c.f. 60% in the rat), thereby confirming that enterohepatic circulation of VPA was of minor importance in determining the pattern of elimination of the drug from blood in the monkey. Urinary excretion of conjugated VPA in intact and bile-exteriorized monkeys totaled 56 and 52% of the 15 mg/kg dose and 60 and 63% of the 150 mg/kg dose, respectively. In monkeys, as in rats, sodium valproate caused a dose-dependent, immediate choleretic reponse, the duration of which followed the blood concentration of the drug.

5-drug adjuvant chemotherapy for breast cancer.

A series of 41 patients at the MGH who received 5-drug chemotherapy, cyclophosphamide, methotrexate, 5-fluorouracil, vincristine and prednisone, (CMF VP) as adjuvant to surgical treatment of operable breast cancer with 4 or more positive axillary nodes is compared to an analogous group of patients treated with cyclophosphamide, methotrexate and 5-fluorouracil (CMF) reported by Bonadonna et al. in an effort to assess the contribution of the treatment program to disease control. The MGH pattern of disease free survival closely parallels that of Bonadonna. Median disease-free survival among the 24 patients who have not recurred is 27 months; among those who recurred 18 months. The analogous medians for treated patients in the Bonadonna study are 24 months and 16 months, as compared to 27 months and 8 months for his nontreated controls. The treatment program, carried out over a two year period, was well tolerated with excellent patient compliance. There was no significant impact, however, in the disease-free survival of postmenopausal patients. While use of this regimen improved disease-free survival in premenopausal individuals, it is clear that a great deal of room for improvement exists, and newer regimens should be investigated.

A disorder of biogenic amines in dihydropteridine reductase deficiency.

A severe deficiency of dihydropteridine reductase (DHPR) in liver, brain, and cultured skin fibroblasts was demonstrated in a child with hyperphenylalaninemia and an atypical form of phenylketonuria. DHPR is required for regeneration of the cofactor, tetrahydrobiopterin. The cofactor is essential in hydroxylation of aromatic amino acid precursors in the biosynthesis of neurotransmitters, serotonin, dopamine, and norepinephrine. In gray tissue at brain biopsy, dopamine was low at 3 ng per gram of tissue, serotonin was barely detected, and norepinephrine appeared high at 1600 ng per gram. In cerebrospinal fluid, homovanillic acid (HVA) was low normal at 33 ng/ml, 5-hydroxyindoleacetic acid (5-HIAA) was low at 4.2 ng/ml, and after a high dose of oral probenecid there was impaired accumulation of HVA to 128 ng/ml and 5-HIAA to 22.4 ng/ml. When the patient was 22 months of age, treatment with hydroxylated aromatic amino acid precursors was initiated, and after three months HVA and 5-HIAA levels were increased in CSF. The apparent restoration of biogenic amines in brain appears to have delayed the rate of neurological deterioration. DHPR activity in cultured skin fibroblasts of children with persistent hyperphenylalaninemia should permit early diagnosis and early treatment of this disorder.