Biomedical subjects

V Prado

Publications and source records attributed to V Prado.

At least 37 records · Page 2Linked to original sources

PubMed1999

[Emergence of resistance to macrolides in Streptococcus pyogenes].

BACKGROUND: Diseases produced by Streptoccocus pyogenes are still a problem in Chile, as in the rest of the world. It exhibits in vitro susceptibility to different antimicrobials, but penicillin continues to be the treatment of choice. Alternative drugs have been developed for allergic patients, such as erythromycin, new macrolides and cephalosporins. Nevertheless, resistant strains are appearing due to the indiscriminate use of macrolides. AIM: To assess present antimicrobial susceptibility of S Pyogenes strains isolated from chilean patients. MATERIAL AND METHODS: The susceptibility to penicillin, macrolides, clindamycin, cephalotin and vancomycin of 153 S Pyogenes strains, obtained from different health centers of the Metropolitan Region and isolated between 1996 and 1998, was assessed using the Kirby-Bauer method. Agar dilution minimal inhibitory concentration was then determined to macrolide resistant strains. RESULTS: All strains were susceptible to penicillin. There was a 7.2% cross-resistance to macrolides. CONCLUSIONS: These results confirm that S Pyogenes resistance to macrolides has increased considerably in the Metropolitan Region of Chile during the last years.

Anti-Bacterial Agents↗

PubMed1998

Capsular serotype and antibiotic resistance of Streptococcus pneumoniae isolates in two Chilean cities.

We compared the incidence of nasopharyngeal colonization by Streptococcus pneumoniae, the serotypes causing mucosal and invasive diseases, and the antibiotic resistance of these strains in patients admitted to three large hospitals and children attending day care centers in two Chilean cities (Santiago and Temuco). The populations in both cities were similar in ethnic background, socioeconomic status, family size, and access to medical care. Significant differences in nasopharyngeal colonization rates, in serotypes causing infections, and in antibiotic resistance were found between the two cities. In children 0 to 2 years of age, 42% were colonized with S. pneumoniae in Santiago compared to 14% in Temuco. A total of 41 serotypes were identified in both Chilean cities studied. Six serotypes were found only in Santiago; 14 serotypes were found only in Temuco. Antibiotic-resistant serotypes 6A, 6B, 14, 19F, and 23F were detected only in Santiago. We show that important differences in the incidence of nasopharyngeal carriage, infection, and S. pneumoniae serotypes can exist in similar populations in different areas of the same country. Our findings are relevant for prevention strategies, antibiotic usage, and vaccine design.

Adolescent↗

PubMed1998

Prevalence of astrovirus infection among Chilean children with acute gastroenteritis.

The frequency of astrovirus infection in 456 Chilean children with diarrhea was determined by enzyme-linked immunosorbent assay, reverse transcriptase PCR, and cell culture. Astrovirus was detected in 16.5% of rotavirus-negative and 7% of rotavirus-positive samples obtained from emergency rooms or hospitals and in 11% of samples from day care centers. HAst-1 was the predominant serotype identified.

Acute Disease↗

PubMed1998

[Antimicrobial multiresistance of Shigella sp strains in a semi rural community of northern Santiago].

UNLABELLED: Appropriate antimicrobial therapy shortens the duration of Shigellosis and significantly reduces the risk of transmission. Shigella strains resistant to common antimicrobials have increased during the past years, determining the need for a periodic surveillance, to guide effective therapy. AIM: To report the results of a surveillance program in a rural community near Santiago (Colina), for Shigella infections. MATERIAL AND METHODS: Between 1995 and 1997, stool samples from 3,534 episodes of diarrhoea, that occurred in Colina, were obtained. Two hundred twenty six Shigella strains were isolated and studied for susceptibility to ampicilin (AM), amoxicillin/clavulanic acid (AMC), cotrimoxazole (STX), chloramphenicol (CAF), tetracycline (TET), furazolidine (FU), ciprofloxacine (CIPR), nalidixic acid (AC NAL), gentamycin (GENT) and cefotaxime (CFTX). RESULTS: Shigella flexnerii represented 134 of 226 Shigella strains isolated. All strains were susceptible to CIPR, AC NAL, GENT and CFTX. Yearly variation of resistance patterns to other antimicrobials were observed for these strains. Resistance to AM varied from 56 to 76%, to AMC from 25 to 56%, to STX from 21 to 47%, to CAF from 36 to 69%, to TET from 44 to 78% and to FU from 9 to 18%. Overall resistance was higher during 1997. All 85 strains of S sonnei were susceptible to CIPR, AC NAL and CFTX. Resistance throughout the years varied from 56 to 88% for AM, from 0 to 28% for AMC, from 44 to 53% for STX, from 11 to 40% for CAF, from 11 to 42% for TET and from 5 to 11% for FU. Overall resistance was also higher during 1997, except for AM and STX. Seven S hoydii strains were isolated, only during 1995. All seven were resistant to AM and TET and none were resistant to FU, CIPR, AC NAL and CFTX. Two strain was resistant to AMC, STX and CAF. CONCLUSIONS: Antimicrobial resistance patterns of Shigella sp isolated in Colina have increased from 1995 to 1997, specially for commonly used antimicrobials. Resistance remains low for furazolidine and all strains remain susceptible to quinolones.

Child, Preschool↗

PubMed1998

[Efficacy and tolerance of a five day course of ciprofloxacin in the treatment of urinary tract infection in women. Multicenter study].

BACKGROUND: There is no consensus about the ideal antimicrobial agent and duration of treatment for urinary tract infection in women. AIM: To assess the efficacy of a five days course of ciprofloxacin for the treatment of urinary tract infection in women. PATIENTS AND METHODS: Women with urinary tract infection were treated with ciprofloxacin (Baycip, Bayer) 250 mg bid during 5 days. Patients were evaluated three to four days after treatment start, two to seven days and one month after treatment end. RESULTS: Of 101 eligible women, 96 aged 18 to 65 years old, coming from three major Chilean cities, participated in the study and 80 completed the follow up period. There was a 95% clinical success, 2.5% partial improvement and 2.5% treatment failure. The causal microorganism was erradicated in 90% of cases, in 1.2% treatment failed and in 8.7% a re-infection occurred. Adverse effects attributable to the drug were observed in 12 patients (headache in 3, gastrointestinal disturbances in 8, somnolence in 1 and irritability in 1). CONCLUSIONS: Ciprofloxacin is an useful antimicrobial for the treatment of lower urinary tract infection in women.

Adolescent↗

PubMed1997

Detection and characterization of enterohaemorrhagic Escherichia coli in slaughtered cattle.

Fecal samples from slaughtered cattle were studied for enterohaemorrhagic Escherichia coli (EHEC) by DNA hybridization with biotin-labelled DNA probes specific for the EHEC virulence plasmid, Shiga-like toxin I (SLT I), Shiga-like toxin II (SLT II) and eae gene. Among 136 animals analysed, 47 (34.5%) were found to carry EHEC. The cytotoxic genotypes observed for EHEC strains were: 60.4% SLT I, 12.5% SLT II and 10.4% SLT I + SLT II; 16.7% resulted SLT I and SLT II negative. A total of 14 out of 48EHEC strains (29.2%) hybridized with a fimbrial probe and 14 of 48 strains with an sas probe. An important number of strains (18 out of 48) belonged to serogroups O157, O26 and O111, serogroups also commonly isolated from haemolytic uremic syndrome cases in Chile. While EHEC isolates from the same animal were usually of the same serogroup, one animal was found to carry two EHEC strains of different serogroups. A total of 50% of EHEC strains were sorbitol negative, irrespective of the O serogroup or EHEC genotypic profile. Results obtained in this study strongly suggest that cattle in Chile are a reservoir of EHEC associated with disease in humans.

Abattoirs↗

PubMed1997

[Isolation and characterization of Yersinia enterocolitica from pigs and bovines in Chile].

The occurrence of Yersinia enterocolitica in tonsils and rectal swabs from 100 healthy pigs and the rectal swabs of 100 healthy cattle slaughtered at Santiago-Chile were analysed. Yersinia enterocolitica was isolated from 48 (48%) pigs but not from cattle. 98.2% of strains were of 4/O3 bioserogroup, considered to be pathogenic for humans. All of the strains were resistant to penicillin producing beta-lactamase. Most of them were resistant to neomicin and tetracycline. The pYV marker was used to demonstrate pathogenicity in all strains by four different assays: 65.5% of the strains were pYV positive by their plasmid profile; 73.3% by crystal violet binding; 84.5% by calcium dependency and 87.9% by hybridization with probe associated with cytotoxicity to Hep-2 cells in vitro. All of the Yersinia enterocolitica strains were pYV positive with at least one of the four tests analysed, 46/58 strains were positive by three tests simultaneously. The similarities between associated cytotoxic genes of porcine and human strains is discussed. The phenotypic and genotypic characteristics demonstrated by the isolates strains suggest that the pigs in Chile are reservoir of potential pathogenic Yersinia enterocolitica for humans.

Animals↗

PubMed1997

[Temporal variation of genotypes and serotypes of enterohemorrhagic E Coli isolated from Chilean children with intestinal infections or hemolytic uremic syndrome].

BACKGROUND: Infections by enterohemorrhagic E. Coli may be asymptomatic, may cause diarrhea, sometimes bloody or a hemolytic uremic syndrome in 2 to 7% of children. These diseases appear sporadically or as outbreaks. Host and agent factors influence the appearance of hemolytic uremic syndrome. AIM: To study the distributions and prevalence of virulence genes and enterohemorrhagic E. Coli serogroups isolated from Chilean children. MATERIALS AND METHODS: Thirty six strains isolated from children with hemolytic uremic syndrome (8 obtained in 1988-1989, 15 obtained in 1990-1993 and 13 obtained in 1995-1996), 33 strains from asymptomatic children, obtained in similar periods and 30 strains from children with bloody diarrhea, obtained in 1995-1996 were studied. Virulence factors were investigated with a colony hybridization technique using probes that identify virulence genes. Serotypes were identified with commercial antisera. RESULTS: Both SLTI and SLTII genes predominated in strains obtained from children with hemolytic uremic syndrome in 1988-1989 and 1995-1996 and SLTI gene predominated in strains obtained in 1990-1993. Similar temporal variations in virulence genes of strains obtained from asymptomatic children were observed. SLTI/SLTII pattern predominated in strains obtained from children with bloody diarrhea and the frequency of O157 serogroup was lower, compared to strains obtained from children with hemolytic uremic syndrome. CONCLUSIONS: There was a temporal variation in toxigenic genotypes of enterohemorrhagic E. Coli strains, but no association between these genotypes and the risk for hemolytic uremic syndrome was observed.

Chi-Square Distribution↗

PubMed1997

[Chlamydia trachomatis infection in asymptomatic Chilean men and with urethritis. Usefulness of first catch urine samples].

BACKGROUND: Chlamydia trachomatis is responsible for 30 to 50% of genital tract infections and is present, without symptoms, in 20% of men and 60% of women. We have little information in Chile about the prevalence of this infection. AIM: To assess the prevalence of Chlamydia trachomatis in men, using first catch urine samples. SUBJECTS AND METHODS: Three hundred and fifty one first catch urine samples of asymptomatic men and 50 samples coming from men with a primary urethritis, were analyzed. Urethral discharge samples from the latter were simultaneously studied. Analysis was performed using an enzyme immuno analysis (MicroTrak Chlamydia EIA, Syva Co.) and a nested polymerase chain reaction towards the gene that codifies MOMP (PCR/OMP). RESULTS: Among asymptomatic men, two of 154 teenagers aged 18 to 19 years old (1.3%), 10 of 100 university students (10%) and eight of 97 adults over 30 years old (8.2%), were infected. The global prevalence of infection in these men was 5.7%. The prevalence of infection in men with urethritis was 12%. Urine EIA had a higher detection frequency than PCR/OMP, but according to another PCR assay, these results were false positives. EIA in first catch urine, had a sensitivity, specificity, positive and negative predictive value of 83.3, 75, 31.3 and 97% respectively, for the detection of Chlamydia trachomatis. The figures for PCR/OMP were 100% for all these parameters. CONCLUSIONS: The prevalence of Chlamydia trachomatis infection in Chilean men is similar to that reported in developed countries. Enzyme immuno assay in first catch urine had a good diagnostic accuracy and could be used in epidemiological studies in asymptomatic men.

Adolescent↗

PubMed1996

[Emergent infectious diseases: a new problem?].

Are the emergent pathogenic microbes, persistent bacteria that have changed their virulence or new diagnostic techniques now allow their recognition? Or, have they found a new possibility of transmission due to ecological, social or cultural changes? The present Editorial analyses the geographical distribution, features and host factors that favor infections by Helicobacter pylorii, Enterohemorrhagic E. Coli, invasive Streptococcus pyogenes and Borrelia Burgdorferi. The surveillance and care of infections caused by emergent germs requires laboratory learning programs as those established in the United States.

Bacterial Infections↗

PubMed1996

Verocytotoxin-producing Escherichia coli infection in family members of children with hemolytic uremic syndrome.

Thirty-four hemolytic uremic syndrome (HUS) patients and ninety-five family members were studied to determine the frequency of infection with verocytotoxin-producing Escherichia coli (VTEC) in household contacts using three diagnostic criteria: VTEC strains isolation and characterization, detection of free fecal VT (FVT) and VT-neutralizing antibodies (VT-NAbs). Gastrointestinal tract symptoms occurred in one to six family members in 8 (23.5%) of the index cases, the week before admission to hospital or simultaneously. The control group consisted of 34 children with acute gastroenteritis who did not develop HUS. Cumulative evidence of VTEC infection was found in 13 (38.2%) of 34 HUS patients, in 30 (31.6%) of 95 family members and in 10 (29.4%) of 34 control children. The serotypes of VTEC isolated were O157: H7 and O25: H2. The prevalent VT type was VT2 in VTEC and FVT; and VT1 in VT-NAbs. Both parents had the same infection rate by fecal toxin or serological data (11.1% FVT, 32% VT-NAbs). These were higher than those detected in siblings (6.2% FVT, 23.5% VT-NAbs) and grandparents (0% FVT, 18% VT-NAbs). Of 16 patients without evidence of infection, 3 had household contacts with FVT and 13 with VT-NAbs. Our results show the wide dissemination of VTEC in the population of Argentina and that family members of HUS patients are usually infected. Therefore, person-to-person transmission may play an important role in the high incidence of HUS in our country.

Bacterial Toxins↗

PubMed1996

[Phenotypic and molecular features of Vibrio cholerae isolated in Chile, Peru and Bolivia. Comparison with environmental reservoirs].

BACKGROUND: Since 1991, a massive cholera epidemic started in Peru and involved most Central and South American Countries. In Chile, 147 cases were registered, the last one in 1995. AIM: To study the phenotypic and molecular features of Vibrio cholerae strains isolated from patients in Perú, Bolivia and Chile and from environmental reservoirs in Santiago, Chile. MATERIALS AND METHODS: The phenotype, biotype and susceptibility to nine antimicrobials was determined for each isolated strain. Also, the genes of cholera and termolabile toxins were determined using DNA probes and a chromosomal restriction profile was done using HindIII, EcoRI and NotI enzymes. RESULTS: Features studied were similar in the 53 strains isolated from patients. Those isolated from environmental reservoirs had different antimicrobial susceptibility, showing ampicillin resistance, and the GT gene was detected in one of 20 strains, compared to clinical samples were it was present in all. Strains isolated from patients and environment had similar chromosomal restriction profiles. CONCLUSIONS: The chromosomal restriction profile gives an image of bacterial genome and it is a useful and reliable tool for the epidemiological surveillance of cholera.

Bolivia↗

PubMed1995

Attenuated live cholera vaccine strain CVD 103-HgR elicits significantly higher serum vibriocidal antibody titers in persons of blood group O.

Persons of blood group O are at increased risk of developing cholera gravis. In a randomized, placebo-controlled, double-blind safety-immunogenicity trial of live oral cholera vaccine CVD 103-HgR in 5- to 9-year-old Chilean children, vibriocidal antibody seroconversion (74% overall) did not differ by blood group. However, the reciprocal geometric mean titer (GMT) in blood group O vaccines (GMT = 486) was higher than that in non-O vaccines (GMT = 179) (P < 0.02).

ABO Blood-Group System↗

PubMed1995

Sorbitol-negative phenotype among enterohemorrhagic Escherichia coli strains of different serotypes and from different sources.

Enterohemorrhagic Escherichia coli (EHEC) strains detected with DNA probes (for virulence plasmid and Shiga-like toxins) from subjects with hemolytic-uremic syndrome (n = 19) or diarrhea (n = 41) or asymptomatic carriers (n = 29) were examined for sorbitol fermentability, as were enterotoxigenic (n = 40), enteropathogenic (n = 40), and enteroinvasive (n = 40) E. coli and urinary tract infection (n = 40) strains and normal flora E. coli strains (n = 40). Sorbitol negativity was common only in EHEC, particularly among strains from severe clinical infections. All 19 EHEC strains from patients with hemolytic-uremic syndrome, irrespective of O:H serotype or Shiga-like toxin genotype, were sorbitol negative.

Carrier State↗

PubMed1995

[Enterohemorrhagic Escherichia coli in hemolytic uremic syndrome in Chilean children. Evaluation of different technics in the diagnosis of the infection].

Enterohemorrhagic Escherichia coli (EHEC), have been associated with pathogenesis of hemolytic uremic syndrome (HUS) worldwide. Our aim was to determine the association of EHEC infection and HUS in Chilean children. During may 1991 and october 1993, 34 children with HUS and 33 age matched controls (children with diarrhea that did not develop HUS) were enrolled in a case/control study. For each child a stool and serum sample were obtained at admission. Stools were processed for common enteropathogens and for EHEC identification. EHEC were identified in stools by gene probes for different virulence factors (EHEC plasmid-associated fimbria, Shiga-like toxin I, Shiga-like toxin II and eae adherence factor) and by detection of free fecal toxin by a neutralization assay in Vero cells. Sera were processed for anti-cytotoxin antibodies also by an assay in Vero cells. Enteropathogens were isolated in 20.6% and 15.5% of HUS and control children respectively (p = NS). 91% of the HUS children and 73% of the control children were EHEC positive by one or more of the techniques used (p = 0.05). Of the three detection methods used for EHEC, only free fecal cytotoxin was significantly more common in HUS children than controls (45.5% vs 9% p = 0.007). Genotype patterns of HUS and controls strains were similar except for a trend towards a higher frequency of non-toxigenic strains in the control group. Serogroup O157 was more common in HUS children than in controls (9% vs 0% p = 0.036). In Chile as in other countries, EHEC infection is common and significantly associated with occurrence of HUS. Infection with EHEC strain O157 seems to be an important risk factor for HUS.

Bacterial Typing Techniques↗

PubMed1995

[Antigenic types of circulating rotavirus in children with acute diarrhea in Santiago de Chile].

Protective immunity against rotavirus infection is directed against antigenic epitopes on the outer capsid proteins VP7 and VP4. The aim of this study was to characterize the VP7 and VP4 antigenic types circulating in different hospital areas of Santiago, Chile, over different time periods. Between April 1993 and April 1994 a total of 1206 stool samples were obtained from children consulting for acute no bloody diarrhea in 5 hospitals representative of the 5 major health areas of Santiago. In addition, 256 rotavirus positive samples, obtained from children with acute diarrhea consulting in the north health area of Santiago between 1985-1987 were studied. All samples were processed for rotavirus by an ELISA and all rotavirus positive samples were VP7 typed (types G1-G4) by a monoclonal antibody based ELISA. 50 rotavirus positive samples were selected for VP4 typing by PCR (types P1-P4). A total of 782 rotavirus positive samples were obtained of which 618 (79%) were typable for one specific VP7 type. VP7 type G1 represented 63% of the rotavirus positive samples and predominated in all areas evaluated throughout the entire period of observation. VP7 type G2 represented 13% of rotavirus samples, following G1 in predominance. G2 types decreased progressively in all areas in both study periods. G4 types were detected mainly during 1985-1987, and G3 types have so far not been detected. Preliminary analysis of VP4 types suggests that P1 types are predominant and closely associated with VP7 G1 type. These results are relevant for the adoption of appropriate preventive strategies for rotavirus infection, specifically aimed to the development of effective vaccines.

Acute Disease↗

PubMed1995

[In vitro susceptibility of enterohemorrhagic Escherichia coli to 11 antimicrobials. Relationship between antibiotic resistance and toxigenic genotype].

Enterohemorrhagic E coli (EHEC) has been recognized as the main etiologic agent of hemorrhagic colitis and hemolytic uremic syndrome (HUS). The usefulness of antibiotic treatment in patients with EHEC infections is a matter of current debate. Knowledge on EHEC antimicrobial susceptibility patterns in different geographic areas is important for both treatment considerations and for strain characterization. We studied by diffusion disk agar technique the antibiotic susceptibility of 83 EHEC strains obtained from stools of patients with HUS or diarrhea. Eleven antimicrobials were tested (ampicillin, cotrimoxazole, tetracycline, chloramphenicol, furazolidone, gentamycin, amikacin, ciprofloxacin, erythromycin, vancomycin, and metronidazol). Resistant strains by disk diffusion were tested for MIC (mg/ml) by agar dilution. SLT-I and SLT-II were detected with specific biotinylated gene probes. All 83 strains were susceptible to furazolidone, ciprofloxacin, gentamycin and amikacin. Resistance was detected to tetracycline 4%, chloramphenicol 5%, cotrimoxazole 24% and ampicillin 25%. As expected for EHEC strains all were resistant to erythromycin, vancomycin, and metronidazol. Resistant strains were significantly more common in non toxigenic and SLT-I producing strains (p = 0.01). Resistant strains were similarly distributed among patients who had diarrhea only and those who developed HUS (p = 0.3). In Chile, resistant EHEC strains seem to be more common and of different genotypes than those reported in more developed countries. Regional differences of EHEC antibiotic susceptibility patterns indicate a need for continuous monitoring, specially if antibiotics prove to be useful in disease prevention.

Child, Preschool↗

PubMed1995

[In vitro comparative activity (E test) of sparfloxacin and other 8 antimicrobial agents against bacteria isolated from patients with respiratory infections acquired in the community].

Sparfloxacin is a new antimicrobial that, while maintaining a good activity against gram negative bacilli, has a better in vitro activity against gram positive bacteria such as S pneumoniae, intracellular pathogens and anaerobic bacteria. The aim of this work was to study the in vitro activity of sparfloxacin against bacteria isolated from patients with community acquired respiratory infections between October 1994 and January 1995. Using the E-test technique, we studied the susceptibility to sparfloxacin, ciprofloxacin, ampicillin, amoxicillin/clavulanic acid, cefuroxime, cefotaxime, erythromycin, methicillin and nalidixic acid of 50 strains of S pneumoniae, 50 strains of H. influenzae, 50 strains of S aureus and 50 strains of S pyogenes. Sparfloxacin was active against 100% of S pneumoniae, H influenzae and S pyogenes strains. Twenty two percent of S aureus strains were resistant and the MIC 90 was 12 micrograms/ml. Sparfloxacin showed the best in vitro activity against H influenzae and S aureus, a similar activity with ampicillin and cefotaxime against S pneumoniae and a similar activity with ampicillin but superior to all other studied antimicrobial against S pyogenes. It is concluded that sparfloxacin is a good antimicrobial for bacteria isolated from patients with respiratory infections.

Anti-Bacterial Agents↗