Shigella sonnei gastroenteritis improves clinically and microbiologically with antibacterial trea... more Shigella sonnei gastroenteritis improves clinically and microbiologically with antibacterial treatment; however choosing a useful drug is a universal challenge because of in vitro susceptibility of S. sonnei frequently evolves to be resistant. To evaluate in vitro susceptibility of S. sonnei strains isolated from patients attending at the Chilean Región Metropolitana and to know the evolution that resistant patterns of S. sonnei have experienced. In this study, the antimicrobial susceptibility profile of 277 isolates of Shigella sonnei was compared. The analyzed periods of time were: period I (1995-1997) 85 strains; period II (2004-2006) 92 strains and period III (2008-2009) 100 strains, in Santiago, Chile. The method performed to analyze susceptibility patterns was the disc diffusion (Kirby-Bauer). The strains showed rates of resistance to ampicillin: period I, 85.8%; period II, 53.3%; period III, 100%, trimethoprim/sulfamethoxazole: period I, 50.5%; period, II 46.7%; period III, 100%, chloramphenicol: period I, 36.4%; period II, 12%; period III, 100% and tetracycline: period I, 38.8%; period II, 30.4%; period III, 100%. 98.9% of the strains showed susceptibility to quinolones. Significant differences were observed in patterns of antimicrobial resistance for both individuals and for multidrug resistance (≥ 3 antimicrobials) in the three periods (p < 0.001, χ2 test). Of all resistant strains, 17% were resistant to 1 or 2 antibiotics, while 65.7% showed a pattern of multidrug resistance; 100% of the period III strains presented multidrug resistance. These results showed the temporal resistance dynamics of S. sonnei circulating strains in the Chilean Región Metropolitana. Due to the endemic behavior of shigellosis in Chile, it is urgent to maintain permanent surveillance of antimicrobial resistance profiles to improve both prevention and treatment of shigellosis.
Shiga-toxin producing Escherichia coli (STEC) is the etiologic agent of acute diarrhea, dysentery... more Shiga-toxin producing Escherichia coli (STEC) is the etiologic agent of acute diarrhea, dysentery, and hemolytic-uremic syndrome (HUS). There is no approved vaccine for STEC infection in humans, and antibiotic use is contraindicated, as it promotes Shiga toxin production. In order to identify STEC-associated antigens and immunogenic proteins, outer membrane proteins (OMPs) were extracted from STEC O26:H11, O103, O113:H21, and O157:H7 strains, and commensal E. coli strain HS was used as a control. SDS-PAGE, two-dimensional-PAGE analysis, Western blot assays using sera from pediatric HUS patients and controls, and matrix-assisted laser desorption ionization-tandem time of flight analyses were used to identify 12 immunogenic OMPs, some of which were not reactive with control sera. Importantly, seven of these proteins have not been previously reported to be immunogenic in STEC strains. Among these seven proteins, OmpT and Cah displayed IgG and IgA reactivity with sera from HUS patients....
Abstract Rectal swabs were collected from Antarctic fur seal pups Arctocephalus gazella at Cape S... more Abstract Rectal swabs were collected from Antarctic fur seal pups Arctocephalus gazella at Cape Shirreff, South Shetland Islands, and analyzed for the presence of anthro-pogenic pathogens. Two of the 33 pups tested positive for enteropathogenic Escherichia coli ...
Four hundred strains of enterobacteria, isolated before the introduction of trimethoprim as a sin... more Four hundred strains of enterobacteria, isolated before the introduction of trimethoprim as a single agent in Chile, were studied. One hundred and thirty six strains (34%) were resistant to greater than or equal to 8 mg/l of trimethoprim and 118 of these (87%) were also resistant to sulphamethoxazole (156 mg/l). Plasmids were detected in 79% of the trimethoprim-resistant strains; 56% of the strains carried two or more plasmids. Trimethoprim resistance could be transferred by conjugation in 66% of the plasmid-carrying strains; this resistance was co-transferred with a variety of other antibiotic resistance determinants.
The newly described stable enterotoxin producing, enterotoxigenic Escherichia coli, serotype O153... more The newly described stable enterotoxin producing, enterotoxigenic Escherichia coli, serotype O153:H45, capable of expressing colonizing factor antigen I, is frequently isolated as a cause of diarrhea among Chilean children. Hybridization studies of five new strains confirmed previous results which indicated that the stable enterotoxin genes are contained in nonconjugative plasmids ranging in size from 81 to 87 kilobases. The strains expressed similar antibiotic resistance and metabolic properties but differed in their plasmid content.
We previously demonstrated the immunogenicity and tolerability of the serogroup B meningococcal v... more We previously demonstrated the immunogenicity and tolerability of the serogroup B meningococcal vaccine, 4CMenB (Bexsero), in 11-17 y-olds randomized to receive 1, 2, or 3 doses at 1, 2, or 6 mo intervals. Participants in this extension study provided an additional blood sample 18-24 mo after last vaccine dose, to assess persistence of serum bactericidal activity with human complement (hSBA), and to compare with age-matched 4CMenB-naïve controls. In the original study, one month after one 4CMenB dose, 93% of subjects had seroprotective hSBA titers (≥4) against indicator serogroup B strains for individual vaccine antigens (fHbp, NadA and NZOMV), increasing to ~100% after two or three doses. After 18-24 mo, 62-73% of subjects given one dose had titers ≥4 against the three antigens, significantly lower rates than after two (77-94%) or three (86-97%) doses. Only proportions with titers ≥ 4 against NZOMV were significantly different between the two (77%) and three (90%, p < 0.0001) dose groups. These results confirm that two doses of 4CMenB, administered 1 to 6 mo apart, provide good levels of bactericidal activity against serogroup B meningococci, which were sustained at least 18-24 mo in over 64% of adolescents for all three tested vaccine-related antigens.
Clinical and Diagnostic Laboratory Immunology, Mar 1, 1998
We compared the incidence of nasopharyngeal colonization by Streptococcus pneumoniae, the serotyp... more 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.
Enterohemorrhagic Escherichia coli (EHEC), is an emergent pathogen that causes sporadic infection... more Enterohemorrhagic Escherichia coli (EHEC), is an emergent pathogen that causes sporadic infections and outbreaks of gastroenteritis associated with consumption of contaminated food products. Because detection of EHEC in diarrhea patients is not routinely performed, infection is most probably underestimated. To compare three techniques to detect EHEC: Colony hybridization with DNA probes, polymerase chain reaction (PCR) for the detection of stx1 and stx2 genes and immunoenzymatic detection by ELISA (Premier EHEC) of Stx1 and Stx2 toxins. Four outbreaks of food-borne gastroenteritis were studied including 16 patients and 78 strains of E coli. Twenty-one (26.9%) strains, hybridized with the stx1 probe, 1 (1.3%) hybridized only with the stx2 probe and 36 (46.1%) with both probes. PCR amplification for cytotoxin genes was observed in 6 strains (7.7%) from the second outbreak studied. The immunoenzymatic assay detected the cytotoxins in 18 (23.0%), of the 78 studied strains. Agreement bet...
The American journal of tropical medicine and hygiene
Variations in antibiotic resistance patterns were studied among 178 Shigella strains isolated fro... more Variations in antibiotic resistance patterns were studied among 178 Shigella strains isolated from 1997 to 2001 in children less than five years of age with acute diarrhea from Colina, a semi-rural community in Santiago, Chile. The minimal inhibitory concentration of several commonly used antibiotics was determined by the agar dilution method. Shigella strains showed high rates of resistance to ampicillin (82%), cotrimoxazole (65%), tetracycline (53%), and chloramphenicol (49%). Furthermore, 51% of the strains showed resistance patterns to multiple antibiotics. Only 9% of the strains were resistant to amoxicillin-clavulanic acid and no resistance was observed to ciprofloxacin, nalidixic acid, or cefotaxime. Continuous monitoring of resistance patterns in Shigella is essential for establishing and updating guidelines for antibiotic treatment in shigellosis.
Clinical and diagnostic laboratory immunology, 1998
We compared the incidence of nasopharyngeal colonization by Streptococcus pneumoniae, the serotyp... more 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 t...
Shigella sonnei gastroenteritis improves clinically and microbiologically with antibacterial trea... more Shigella sonnei gastroenteritis improves clinically and microbiologically with antibacterial treatment; however choosing a useful drug is a universal challenge because of in vitro susceptibility of S. sonnei frequently evolves to be resistant. To evaluate in vitro susceptibility of S. sonnei strains isolated from patients attending at the Chilean Región Metropolitana and to know the evolution that resistant patterns of S. sonnei have experienced. In this study, the antimicrobial susceptibility profile of 277 isolates of Shigella sonnei was compared. The analyzed periods of time were: period I (1995-1997) 85 strains; period II (2004-2006) 92 strains and period III (2008-2009) 100 strains, in Santiago, Chile. The method performed to analyze susceptibility patterns was the disc diffusion (Kirby-Bauer). The strains showed rates of resistance to ampicillin: period I, 85.8%; period II, 53.3%; period III, 100%, trimethoprim/sulfamethoxazole: period I, 50.5%; period, II 46.7%; period III, 100%, chloramphenicol: period I, 36.4%; period II, 12%; period III, 100% and tetracycline: period I, 38.8%; period II, 30.4%; period III, 100%. 98.9% of the strains showed susceptibility to quinolones. Significant differences were observed in patterns of antimicrobial resistance for both individuals and for multidrug resistance (≥ 3 antimicrobials) in the three periods (p &amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;lt; 0.001, χ2 test). Of all resistant strains, 17% were resistant to 1 or 2 antibiotics, while 65.7% showed a pattern of multidrug resistance; 100% of the period III strains presented multidrug resistance. These results showed the temporal resistance dynamics of S. sonnei circulating strains in the Chilean Región Metropolitana. Due to the endemic behavior of shigellosis in Chile, it is urgent to maintain permanent surveillance of antimicrobial resistance profiles to improve both prevention and treatment of shigellosis.
Shiga-toxin producing Escherichia coli (STEC) is the etiologic agent of acute diarrhea, dysentery... more Shiga-toxin producing Escherichia coli (STEC) is the etiologic agent of acute diarrhea, dysentery, and hemolytic-uremic syndrome (HUS). There is no approved vaccine for STEC infection in humans, and antibiotic use is contraindicated, as it promotes Shiga toxin production. In order to identify STEC-associated antigens and immunogenic proteins, outer membrane proteins (OMPs) were extracted from STEC O26:H11, O103, O113:H21, and O157:H7 strains, and commensal E. coli strain HS was used as a control. SDS-PAGE, two-dimensional-PAGE analysis, Western blot assays using sera from pediatric HUS patients and controls, and matrix-assisted laser desorption ionization-tandem time of flight analyses were used to identify 12 immunogenic OMPs, some of which were not reactive with control sera. Importantly, seven of these proteins have not been previously reported to be immunogenic in STEC strains. Among these seven proteins, OmpT and Cah displayed IgG and IgA reactivity with sera from HUS patients....
Abstract Rectal swabs were collected from Antarctic fur seal pups Arctocephalus gazella at Cape S... more Abstract Rectal swabs were collected from Antarctic fur seal pups Arctocephalus gazella at Cape Shirreff, South Shetland Islands, and analyzed for the presence of anthro-pogenic pathogens. Two of the 33 pups tested positive for enteropathogenic Escherichia coli ...
Four hundred strains of enterobacteria, isolated before the introduction of trimethoprim as a sin... more Four hundred strains of enterobacteria, isolated before the introduction of trimethoprim as a single agent in Chile, were studied. One hundred and thirty six strains (34%) were resistant to greater than or equal to 8 mg/l of trimethoprim and 118 of these (87%) were also resistant to sulphamethoxazole (156 mg/l). Plasmids were detected in 79% of the trimethoprim-resistant strains; 56% of the strains carried two or more plasmids. Trimethoprim resistance could be transferred by conjugation in 66% of the plasmid-carrying strains; this resistance was co-transferred with a variety of other antibiotic resistance determinants.
The newly described stable enterotoxin producing, enterotoxigenic Escherichia coli, serotype O153... more The newly described stable enterotoxin producing, enterotoxigenic Escherichia coli, serotype O153:H45, capable of expressing colonizing factor antigen I, is frequently isolated as a cause of diarrhea among Chilean children. Hybridization studies of five new strains confirmed previous results which indicated that the stable enterotoxin genes are contained in nonconjugative plasmids ranging in size from 81 to 87 kilobases. The strains expressed similar antibiotic resistance and metabolic properties but differed in their plasmid content.
We previously demonstrated the immunogenicity and tolerability of the serogroup B meningococcal v... more We previously demonstrated the immunogenicity and tolerability of the serogroup B meningococcal vaccine, 4CMenB (Bexsero), in 11-17 y-olds randomized to receive 1, 2, or 3 doses at 1, 2, or 6 mo intervals. Participants in this extension study provided an additional blood sample 18-24 mo after last vaccine dose, to assess persistence of serum bactericidal activity with human complement (hSBA), and to compare with age-matched 4CMenB-naïve controls. In the original study, one month after one 4CMenB dose, 93% of subjects had seroprotective hSBA titers (≥4) against indicator serogroup B strains for individual vaccine antigens (fHbp, NadA and NZOMV), increasing to ~100% after two or three doses. After 18-24 mo, 62-73% of subjects given one dose had titers ≥4 against the three antigens, significantly lower rates than after two (77-94%) or three (86-97%) doses. Only proportions with titers ≥ 4 against NZOMV were significantly different between the two (77%) and three (90%, p < 0.0001) dose groups. These results confirm that two doses of 4CMenB, administered 1 to 6 mo apart, provide good levels of bactericidal activity against serogroup B meningococci, which were sustained at least 18-24 mo in over 64% of adolescents for all three tested vaccine-related antigens.
Clinical and Diagnostic Laboratory Immunology, Mar 1, 1998
We compared the incidence of nasopharyngeal colonization by Streptococcus pneumoniae, the serotyp... more 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.
Enterohemorrhagic Escherichia coli (EHEC), is an emergent pathogen that causes sporadic infection... more Enterohemorrhagic Escherichia coli (EHEC), is an emergent pathogen that causes sporadic infections and outbreaks of gastroenteritis associated with consumption of contaminated food products. Because detection of EHEC in diarrhea patients is not routinely performed, infection is most probably underestimated. To compare three techniques to detect EHEC: Colony hybridization with DNA probes, polymerase chain reaction (PCR) for the detection of stx1 and stx2 genes and immunoenzymatic detection by ELISA (Premier EHEC) of Stx1 and Stx2 toxins. Four outbreaks of food-borne gastroenteritis were studied including 16 patients and 78 strains of E coli. Twenty-one (26.9%) strains, hybridized with the stx1 probe, 1 (1.3%) hybridized only with the stx2 probe and 36 (46.1%) with both probes. PCR amplification for cytotoxin genes was observed in 6 strains (7.7%) from the second outbreak studied. The immunoenzymatic assay detected the cytotoxins in 18 (23.0%), of the 78 studied strains. Agreement bet...
The American journal of tropical medicine and hygiene
Variations in antibiotic resistance patterns were studied among 178 Shigella strains isolated fro... more Variations in antibiotic resistance patterns were studied among 178 Shigella strains isolated from 1997 to 2001 in children less than five years of age with acute diarrhea from Colina, a semi-rural community in Santiago, Chile. The minimal inhibitory concentration of several commonly used antibiotics was determined by the agar dilution method. Shigella strains showed high rates of resistance to ampicillin (82%), cotrimoxazole (65%), tetracycline (53%), and chloramphenicol (49%). Furthermore, 51% of the strains showed resistance patterns to multiple antibiotics. Only 9% of the strains were resistant to amoxicillin-clavulanic acid and no resistance was observed to ciprofloxacin, nalidixic acid, or cefotaxime. Continuous monitoring of resistance patterns in Shigella is essential for establishing and updating guidelines for antibiotic treatment in shigellosis.
Clinical and diagnostic laboratory immunology, 1998
We compared the incidence of nasopharyngeal colonization by Streptococcus pneumoniae, the serotyp... more 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 t...
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