Evidence of infection with organisms producing Shiga-like toxins in household contacts of children with the hemolytic uremic syndrome.

We conducted a prospective study in 87 household contacts of 51 children with hemolytic uremic syndrome to determine the frequency of infection with Shiga-like toxin-producing bacteria. Gastrointestinal tract symptoms occurred in only 1 of 87 contacts. Free fecal toxin was detected in 25 of 64 (39%) of the household members. Neutralization with specific antisera to Shiga-like toxins I and II (SLT-I, SLT-II) revealed that in 6 of these household contacts only SLT-I was present in stool, in 10 only SLT-II was present and in 9 both toxins were found. Thirty-three percent of the hemolytic uremic syndrome families in which 2 or more members were studied had more than 1 household member with free fecal toxin in stool. None of the household contacts was found to have E. coli O157:H7 in feces. Serum samples were available in 77 household contacts; 75% (58 of 77) had serum neutralizing titers of greater than or equal to 1:4 to 1 or both toxins. In those contacts for whom paired sera were available, seroconversion was found in 10 of 24 (42%). These data show that household contacts of children with hemolytic uremic syndrome are commonly colonized with Shiga-like toxin-producing E. coli and seroconversion to Shiga-like toxins occurs frequently in family members of children with hemolytic uremic syndrome.

Isolation of three strains of beta-lactamase-producing Enterococcus faecalis in Argentina.

Of the 90 strains of Enterococcus spp. isolated in an Argentine laboratory in the period from January to July 1989, three were identified as beta-lactamase-producing Enterococcus faecalis. According to the literature reviewed, these appear to be the first beta-lactamase-positive strains of Enterococcus isolated outside the USA. They differed from most beta-lactamase-producing strains already described in that they were susceptible to low concentrations of macrolides. All three strains were resistant to high concentrations of aminoglycosides.

Penicillin resistance and aminoglycoside-penicillin synergy in enterococci.

Susceptibility to penicillin, vancomycin, imipenem, streptomycin, kanamycin and gentamicin was tested in 130 clinical isolates of Enterococcus spp. by an agar dilution method. Penicillin resistance (MIC > 8 mg/l) was only observed among strains of Enterococcus faecium and Enterococcus raffinosus. Thirty-nine percent of the penicillin-resistant enterococci showed low-level resistance to at least one of the three aminoglycosides tested (gentamicin, kanamycin and streptomycin). Six Enterococcus strains (5 E. faecium and 1 E. raffinosus) with low-level resistance to gentamicin and different MICs for penicillin were tested for antibiotic synergy using time-killing curves. When penicillin concentrations equal to or higher than the MICs were used, synergism was established, even when highly penicillin-resistant strains (MIC > 200 mg/l) were tested. No synergy was observed when penicillin concentrations were below the MICs.

Intrahospital spread of a single gentamicin-resistant, beta-lactamase-producing strain of Enterococcus faecalis in Argentina.

Six beta-lactamase-producing (Bla+) isolates of Enterococcus faecalis recovered over a 17-month period from an Argentinian pediatric hospital were found to have identical or almost identical chromosomal restriction patterns by pulsed-field gel electrophoresis, although the plasmid patterns were different. These isolates, like Bla+ enterococci in the United States, hybridized to a staphylococcal Bla gene probe. The presence of a single strain was somewhat surprising, since all isolates transferred Bla by conjugation.

Lemierre's syndrome: case report in a pediatric patient.

Lemierre's syndrome was described in 1936 as a severe oropharyngeal infection followed by septic thrombophlebitis of the internal jugular vein and disseminated metastatic infections. Cases occur typically in previously healthy young adults and children. Fusobacterium necrophorum is the main anaerobic bacterium implicated. We present a septic 2-month-old infant with mastoiditis, multiple sites of osteoarthritis and multiple subcutaneous abscesses. No underlying anatomic or immunologic abnormalities were identified. Fusobacterium necrophorum was recovered from blood and bone samples obtained intraoperatively. Treatment included anaerobic coverage and drainage of septic foci. The patient was discharged home on 35th hospital day with oral amoxicillin-clavulanic acid and he recovered without sequelae. This was the first case of Lemierre's syndrome in our hospital. We want to highlight the absence of jugular vein thrombophlebitis, the presence of mastoiditis as previous infection and the surprising appearance of this infection in an edentulous 2-month-old infant.

Isolation of moderately penicillin-susceptible strains of Neisseria meningitidis in Argentina.

Four strains that were moderately susceptible to penicillin and/or ampicillin were found among 54 consecutive isolates of meningococci recovered from patients in one pediatric hospital in Argentina from October 1991 to December 1992. Disk diffusion tests performed with 2 U of penicillin failed to detect one strain. These findings suggest that attention should be paid to changes in the susceptibility patterns of meningococci in order to anticipate therapeutic failures in the future.

Detection of high- and moderately high-level resistance to gentamicin and streptomycin in Enterococcus faecium by a disc diffusion method.

We evaluated an agar disc diffusion test for the detection of high-level (> or = 2000 mg/L) and moderately high-level resistance to gentamicin (MIC, > or = 128- < or = 1024 mg/L) and streptomycin (MIC, > or = 256- < or = 1024 micrograms/ml) with 70 clinical isolates of Enterococcus faecium. Results obtained using disks containing 120 micrograms gentamicin and 300 micrograms streptomycin were compared with MICs determined by an agar dilution method. Based on the scattergrams, the closest zone diameter correlations with MIC breakpoints were as follows: susceptible, > or = 16 mm; and resistant, < or = 10 mm, for both streptomycin and gentamicin. No major or very major errors were found with either aminoglycoside using these values. We conclude that agar disk diffusion test can be used to accurately detect high-level or moderately high-level gentamicin and streptomycin resistance in E. faecium.

Hemolytic uremic syndrome and diarrhea in Argentine children: the role of Shiga-like toxins.

Shiga-like toxin-producing Escherichia coli have been associated with hemorrhagic colitis and the hemolytic uremic syndrome (HUS). Because Argentina has the highest reported frequency of HUS in the world, Argentine children were prospectively studied during the HUS seasons for evidence of Shiga-like toxin-related diseases. On the basis of serology, fecal cytotoxin neutralization, stool cultures, and DNA hybridization of colony lysates, most children with HUS had evidence of infection with Shiga-like toxin-producing organisms. Children with spring-summer diarrhea also commonly (32%, confidence interval 18%-46%) had clear-cut evidence of such infection. No controls (children without gastrointestinal, renal, or hemolytic disease) had free fecal cytotoxin, positive cultures for E. coli O157:H7, or DNA probe-positive organisms; 20% of them had low serum titers of antibodies to Shiga-like toxins. E. coli O157:H7 was not common in either HUS or diarrhea patients. The high frequency of Shiga-like toxin-induced diarrhea in young children in Argentina probably explains the high incidence of HUS in this country and suggests that HUS is a relatively uncommon complication of Shiga-like toxin-related disease.

Evidence for clonal spread of a single strain of beta-lactamase-producing Enterococcus (Streptococcus) faecalis to six hospitals in five states.

Beta-lactamase-producing (Bla+) enterococci have been reported in three state and two countries. Pulsed-field gel electrophoresis was used to compare 14 Bla+ Enterococcus (Streptococcus) faecalis isolated from hospitalized patients in seven states and three continents. The restriction endonuclease digestion patterns of isolates from Connecticut, Massachusetts, Lebanon, and Argentina were all markedly different, indicating that these were different strains. However, isolates from Delaware, Texas, Pennsylvania (Philadelphia and Pittsburgh), Florida, and Virginia were similar, indicating that these isolates were derivatives of a single strain. This conclusion was supported by hybridization using individual fragments as probes. Spread of Bla+ enterococci within the hospital setting was also demonstrated. These findings illustrate the value of pulsed-field gel electrophoresis for epidemiologic analyses and support the importance of identifying and containing organisms with new resistance properties in an effort to decrease their transmission to and from, as well as within, hospitals.

Infections in children with malignant disease in Argentina.

During six-month period, 102 consecutive episodes of fever in 68 children (ranging from 1 month to 14 years of age) with malignant diseases were prospectively evaluated. Sixty-five had acute lymphoblastic leukemia, nine had acute myeloblastic leukemia, nine had malignant lymphoma (four Hodgkin and five non-Hodgkin), five had chronic myeloid leukemia, four had rhabdomyosarcoma, three had CNS tumors, two had neuroblastoma, one had Wilms, and four had other malignant tumors. Forty cases (39.2%) showed severe neutropenia (500 neutrophil/m3) during the episode. S. aureus, E. coli, and S. pyogenes were in 53% of the 75 microbiologic isolates. Twenty-two percent of the viral studies were positive. Mycologic studies were all negative, except one case with C. Albicans. Pneumonia (33 cases), cellulitis (15 cases), pharyngitis (12 cases), and varicella (11 cases) were the most common final diagnosis. Seventy-one percent of the episodes were etiologically documented (by bacterial isolate, characteristic serology, and/or typical clinic picture); 19% of the febrile episodes were probable infections, and 10% were fever of uncertain cause. Ninety percent of the cases responded well to therapy, and mortality of this series was 7%. Gentamicin, Carbenicillin, and Methicilin were the more common antibiotics employed. We conclude that in our population 1) infection is a frequent cause of morbidity in children with malignant diseases; 2) the most common cause of the febrile episodes is bacterial infection; 3) S. aureus, E. coli and S. pyrogenes are the most frequent bacterial isolates, and P. aeruginosa is infrequent; 4)viral infections are relatively frequent in this group of children; and 5) with adequate management, the mortality is low.

Helicobacter pylori y enfermedad gastroduodenal: metodología diagnóstica / Helicobacter pylori and gastroduodenal disease: diagnostic work-up

El Hp es agente causal común de gastritis antral y úlcera duodenal en el adulto. No existen en nuestro país estudios pediátricos que confirmen dicha relación. Con el objeto de determinar la presencia de Hp en la mucosa gástrica en niños y su relación con la clínica, laboratorio, endoscopía y anatomía patológica, se estudiaron 44 pacientes de 3 a 12 años (mediana 8), con DAR (n=24) y patología gastroduodenal (n=15). El grupo control fue de 5 pacientes. A todos se les realizó: a) serología para anticuerpos anti Hp IgA e IgG y b) endoscopía digestiva alta con biopsia de antro y cuerpo gástrico para histología, búsqueda de Hp por tinción, test de ureasa rápido y cultivo. Se consideraron infectados los pacientes que tuvieron cultivos positivos o detección histológica del Hp. Se halló Hp en el 33,5 por ciento de los pacientes con DAR, en el 33,3 por ciento de los niños con patología gastroduodenal y en ninguno del grupo de control. El 100 por ciento de los pacientes con gastritis nodular endoscópica fueron Hp positivo demostrando este hallazgo una alta especificidad. En relación a las gastritis histológicas fue hallado en el 76,4 por ciento y solamente en un paciente con DAR y mucosa normal. Esto sugiere una relación directa entre Hp y daño inflamatorio. La sensibilidad fue del 100 por ciento para la histología y del 92,8 por ciento para los anticuerpos. La especificidad fue del 100 por ciento para histología, cultivo y ureasa. Los autores sugieren la utilización de la serología para detectar Hp por tratarse de un método no invasivo con alto grado de sensibilidad y especificidad.

Streptococcus pyogenes: vigilancia de su resistencia a los antibióticos en un hospital pediátrico / Streptococcus pyogenes: surveillance of resistance to antimicrobial at a pediatric hospital

En varios países del mundo comenzaron a aislarse en forma creciente cepas de Streptococcus pyogenes resistentes a eritromicina. Este trabajo tuvo por objeto verificar la sensibilidad a penicilina, lincosamidas y macrólidos de los estreptococos del grupo A aislados en nuestro hospital entre 1989 y 1994. Se estudió un total de 373 cepas aisladas principalmente de exudados faríngeos por el método de dilución en medio sólido. Ninguna cepa resultó resistente a penicilina y sólo en 1989 se aislaron cepas resistentes a eritromicina (1,6 por ciento para ese año). Las dos cepas resistentes presentaron un patrón de sensibilidad compatible con el mecanismo MLS inducible. En conclusión, S. pyogenes continúa siendo uniformemente sensible a penicilina mientras que tanto la eritromicina como los nuevos macrólidos y las lincosamidas mantienen su efectividad in vitro como para seguir siendo considerados como alternativas para el tratamiento de infecciones estreptocócicas en nuestro medio