Although the association between H. pylori and gastric cancer has been well described, the altera... more Although the association between H. pylori and gastric cancer has been well described, the alterations studies are scarce in the humoral immune response in specific anatomical areas of stomach and during the stages of gastric cancer. The aim in this study was to determine the influence of humoral immune responses against H. pylori infection on gastric carcinoma. We selected 16 gastric cancer cases and approximately one matched control per case at the National Institute of Medical Sciences and Nutrition Salvador Zubirán (INCMNSZ); all the cases met the inclusion criteria for the study. We obtained three biopsies from each patient and from each of the predetermined regions of the stomach: antrum, angular portion, corpus, and fundus. From the patients with gastric cancer, additional biopsy specimens were obtained from tumor mid-lesion and tumor margin, and additional specimens were collected at least 2 and 5 cm from the tumor margin. We compared IgA levels against H. pylori in each are...
Annals of Clinical Microbiology and Antimicrobials, 2011
Background Helicobacter pylori is associated with chronic gastritis, peptic ulcers, and gastric... more Background Helicobacter pylori is associated with chronic gastritis, peptic ulcers, and gastric cancer. Two major virulence factors of H. pylori have been described: the pathogenicity island cag (cag PAI) and the vacuolating cytotoxin gene (vacA). Virtually all strains have a copy of vacA, but its genotype varies. The cag PAI is a region of 32 genes in which the insertion
Helicobacter pylori virulence determinants have not previously been studied in detail in Latin Am... more Helicobacter pylori virulence determinants have not previously been studied in detail in Latin Americans with H. pylori infections. We characterized the vacA (vacuolating cytotoxin gene A) and cagA (cytotoxin-associated gene A) types of more than 400 single-colony isolates from 20 patients in Mexico City. For 17 patients H. pylori strains of two or more different vacA genotypes were isolated from gastric biopsy specimens, indicating infection with two or more strains of H. pylori. The most frequent vacA genotype was s1b/m1. vacA diversity was more marked than that described previously, in that isolates from seven patients had untypeable vacA midregions and isolates from nine patients had type s1 signal sequence coding regions which could not be further subtyped. Previously undescribed vacA type s2/m1 strains were found in five patients. All patients were infected with cagA-positive strains, but occasionally, these coexisted with small numbers of cagA-negative strains. In conclusion,...
Culture and identification of Mycobacterium tuberculosis in cerebrospinal fluid (CSF) of patients... more Culture and identification of Mycobacterium tuberculosis in cerebrospinal fluid (CSF) of patients with tuberculous meningitis is slow, and prognosis depends on early diagnosis and treatment. An enzyme-linked immunosorbent assay with commercial BCG and anti-BCG was designed to detect mycobacterial antigens in human body fluids. Absorbance at 405 nm was measured and readings greater than or equal to 0.20 were considered positive. The readings were above 0.20 for four patients with confirmed tuberculous meningitis and nine of twelve patients with probable tuberculous meningitis. In all but one of ten patients with meningitis of other causes and in eleven control subjects the readings were below 0.20. The specificity of the test was 95% and its sensitivity 81.25%.
A cohort of 228 Mexican children less than 5 years old was followed during the enterotoxigenic Es... more A cohort of 228 Mexican children less than 5 years old was followed during the enterotoxigenic Escherichia coli(ETEC) season. The incidence of ETEC diarrhea-associated and asymptomatic infections was determined, and E. coli strains isolated from stool samples were tested for heat-labile and heat-stable toxins and for expression of colonization factor antigens (CFA). Of the children, 61% had at least one ETEC infection. Children with ETEC isolated from stools were more likely to have diarrhea than were ETEC-free age-matched control children (odds ratio [OR] = 4.5; 95% confidence interval [CI] = 2.9-7.0). Strains carrying CFA/IV, CFA/I, or CFA/II were found in 23%, 18%, and 5% of ETEC infections, respectively. The risk of having diarrhea associated with a CFA-expressing versus a CFA-negative ETEC strain was the same (age-adjusted OR = 0.8; 95% CI = 0.4-1.6). These data should be considered in the development of a diarrhea vaccine containing only CFAs.
Helicobacter pylori infection is common in the Mexican population; however, sources, routes, and ... more Helicobacter pylori infection is common in the Mexican population; however, sources, routes, and risk factors for infection as well as mode of transmission remain unclear. H. pylori was detected by polymerase chain reaction (PCR) technique in three aquatic systems located in the Mexico City area. In addition, microbiologic cultures and physicochemical parameters were measured. The systems were sampled over an 18-month period (1997-1999), resulting in a total of 212 samples for the different analyses. Twenty-one percent of the samples (16/77) were positive for H. pylori; of these, 42% (5/12) were confirmed for cagA gene detection by PCR hybridization. Microbiologic samples (n = 74) yielded Aeromonas hydrophila, Aeromonas caviae, Aeromonas veronii, and Vibrio fluvialis. In the samples for physicochemical analyses (n = 61), low concentrations of dissolved oxygen were detected and residual chlorine was less than the inactivation dose, both providing conditions for potential survival of H. pylori and other enteric pathogens in these environments. The results of this study suggest that, in Mexico City, water used for human consumption and irrigation may play an important role as a vehicle in the transmission of H. pylori as well as infection by other known enteric pathogens.
Virulence factors of Helicobacter pylori are associated with peptic ulcer disease and may be also... more Virulence factors of Helicobacter pylori are associated with peptic ulcer disease and may be also associated with bleeding peptic ulcers (BPU). To determine whether H. pylori and/or the cytotoxin-associated gene (cagA) can increase the risk of bleeding in peptic ulcers. Sixty-seven patients were studied. Thirty had BPU, 20 had non-bleeding peptic ulcers (NBPU), and 17 were control subjects (NPU). The prevalence of H. pylori was assessed by the urease fast test, histological examination, serology, and 16S ribosomal RNA and cagA gene amplification by polymerase chain reaction (PCR). Histology and PCR showed greater sensitivity for diagnosis of H. pylori under bleeding circumstances when compared with other tests. Association of H. pylori was greater in the NBPU group (odds ratio [OR] 4.91, P = 0.06) than in the BPU group (OR 1.27, P = NS) when compared with the control group. When the BPU and NBPU groups were compared, H. pylori was found more often in the NBPU group (OR 0.26, P < 0.10 ). The cagA-positive gene showed a similar distribution in the three groups. The titres for anti-CagA immunoglobulin A (IgA) antibodies were higher in NBPU patients (83%) than in BPU or control patients. Furthermore, anti-urease immunoglobulin G (IgG) was detected more frequently among BPU and NBPU patients. NBPU patients had the highest prevalence of H. pylori by PCR. It seems unlikely that either H. pylori or the cagA-positive gene act as significant risk factors for bleeding in peptic ulcers. The lower prevalence of the microorganism among patients who bleed cannot be explained as an artificial finding.
The effectiveness of Bacillus Calmette-Guerin (BCG) vaccination in reducing tuberculosis (TB) pre... more The effectiveness of Bacillus Calmette-Guerin (BCG) vaccination in reducing tuberculosis (TB) prevalence rates is poor, resulting in urgent need for improved immunization programs, with new and more effective vaccines against TB. To develop a recombinant Tice BCG vaccine against TB that overexpresses the 38-kDa antigen of Mycobacterium tuberculosis in order to protect against infection by M. tuberculosis H37Rv and hyper-virulent M. tuberculosis Beijing genotype. M. tuberculosis 38-kDa protein was cloned into a mycobacterial shuttle plasmid, which was used to overexpress the 38 kDa protein in BCG Tice to produce the recombinant vaccine, rBCG38 Tice (rBCG38). Compared with BCG Tice, which conferred little protection against the Beijing strain of M. tuberculosis, vaccination with the rBCG38 increased survival of mice infected with either M. tuberculosis H37Rv or a Beijing strain of M. tuberculosis, isolate 9501000. Vaccination with either BCG Tice or rBCG38 resulted in enhanced protection against mycobacterial growth in lung tissue by reducing the number of colony-forming units (CFU). The vaccine induced a strong and highly significant Th1 response, shown by the high level of IL-2 and IFN-gamma cytokine producer cells found in the lungs of challenged mice, and an increase in the IgG2a:IgG1 ratio found in the pooled sera of the vaccinated mice. This study showed that rBCG38 vaccine induced a strong Th1 response, demonstrated by the high levels of IL-2 and IFN-gamma producer cells and IgG2a. Protection was mediated for as long as 6 and 4 months after challenge with M. tuberculosis H37Rv and Beijing genotypes, respectively.
Campylobacter jjuni is an important cause of diarrhea in humans throughout the world [1-3]. It is... more Campylobacter jjuni is an important cause of diarrhea in humans throughout the world [1-3]. It is capable of in-testinal invasion [4, 5], but also, C. jejuni can induce a secretory diarrhea such as that caused by enterotoxin-producing organisms, especially in children [2]. Our find- ...
ABSTRACT The susceptibility to 14 beta-lactam and non-beta-lactam antimicrobial agents was evalua... more ABSTRACT The susceptibility to 14 beta-lactam and non-beta-lactam antimicrobial agents was evaluated for Streptococcus pneumoniae from patients with community-acquired respiratory infections in a Mexican medical center. Three hundred fifteen pneumococcal isolates obtained from patients between 1995 and 2001 were tested by the broth microdilution test. Fifty-two percent of the isolates were nonsusceptible to penicillin (minimal inhibitory concentration, >0.06 microg/mL). Penicillin-nonsusceptible isolates were more likely to exhibit resistance to cephalosporins, macrolides, ciprofloxacin, trimethoprim/sulfamethoxazole, chloramphenicol, and tetracycline when compared to penicillin-susceptible isolates. Ninety-three percent of the penicillin-nonsusceptible isolates were resistant to at least one other class of antimicrobials, in contrast to only 47% of the penicillin-susceptible strains (p < 0.0001). More than 90% of the tested isolates were susceptible to amoxicillin/clavulanate, ceftriaxone, levofloxacin, and gatifloxacin. Reduced susceptibility to penicillin was considered to be a reliable marker for the higher probability of multidrug resistance, thus requiring in vitro tests to guide chemotherapy or the choices of parenteral extended spectrum cephalosporins or newer respiratory quinolones.
Although the association between H. pylori and gastric cancer has been well described, the altera... more Although the association between H. pylori and gastric cancer has been well described, the alterations studies are scarce in the humoral immune response in specific anatomical areas of stomach and during the stages of gastric cancer. The aim in this study was to determine the influence of humoral immune responses against H. pylori infection on gastric carcinoma. We selected 16 gastric cancer cases and approximately one matched control per case at the National Institute of Medical Sciences and Nutrition Salvador Zubirán (INCMNSZ); all the cases met the inclusion criteria for the study. We obtained three biopsies from each patient and from each of the predetermined regions of the stomach: antrum, angular portion, corpus, and fundus. From the patients with gastric cancer, additional biopsy specimens were obtained from tumor mid-lesion and tumor margin, and additional specimens were collected at least 2 and 5 cm from the tumor margin. We compared IgA levels against H. pylori in each are...
Annals of Clinical Microbiology and Antimicrobials, 2011
Background Helicobacter pylori is associated with chronic gastritis, peptic ulcers, and gastric... more Background Helicobacter pylori is associated with chronic gastritis, peptic ulcers, and gastric cancer. Two major virulence factors of H. pylori have been described: the pathogenicity island cag (cag PAI) and the vacuolating cytotoxin gene (vacA). Virtually all strains have a copy of vacA, but its genotype varies. The cag PAI is a region of 32 genes in which the insertion
Helicobacter pylori virulence determinants have not previously been studied in detail in Latin Am... more Helicobacter pylori virulence determinants have not previously been studied in detail in Latin Americans with H. pylori infections. We characterized the vacA (vacuolating cytotoxin gene A) and cagA (cytotoxin-associated gene A) types of more than 400 single-colony isolates from 20 patients in Mexico City. For 17 patients H. pylori strains of two or more different vacA genotypes were isolated from gastric biopsy specimens, indicating infection with two or more strains of H. pylori. The most frequent vacA genotype was s1b/m1. vacA diversity was more marked than that described previously, in that isolates from seven patients had untypeable vacA midregions and isolates from nine patients had type s1 signal sequence coding regions which could not be further subtyped. Previously undescribed vacA type s2/m1 strains were found in five patients. All patients were infected with cagA-positive strains, but occasionally, these coexisted with small numbers of cagA-negative strains. In conclusion,...
Culture and identification of Mycobacterium tuberculosis in cerebrospinal fluid (CSF) of patients... more Culture and identification of Mycobacterium tuberculosis in cerebrospinal fluid (CSF) of patients with tuberculous meningitis is slow, and prognosis depends on early diagnosis and treatment. An enzyme-linked immunosorbent assay with commercial BCG and anti-BCG was designed to detect mycobacterial antigens in human body fluids. Absorbance at 405 nm was measured and readings greater than or equal to 0.20 were considered positive. The readings were above 0.20 for four patients with confirmed tuberculous meningitis and nine of twelve patients with probable tuberculous meningitis. In all but one of ten patients with meningitis of other causes and in eleven control subjects the readings were below 0.20. The specificity of the test was 95% and its sensitivity 81.25%.
A cohort of 228 Mexican children less than 5 years old was followed during the enterotoxigenic Es... more A cohort of 228 Mexican children less than 5 years old was followed during the enterotoxigenic Escherichia coli(ETEC) season. The incidence of ETEC diarrhea-associated and asymptomatic infections was determined, and E. coli strains isolated from stool samples were tested for heat-labile and heat-stable toxins and for expression of colonization factor antigens (CFA). Of the children, 61% had at least one ETEC infection. Children with ETEC isolated from stools were more likely to have diarrhea than were ETEC-free age-matched control children (odds ratio [OR] = 4.5; 95% confidence interval [CI] = 2.9-7.0). Strains carrying CFA/IV, CFA/I, or CFA/II were found in 23%, 18%, and 5% of ETEC infections, respectively. The risk of having diarrhea associated with a CFA-expressing versus a CFA-negative ETEC strain was the same (age-adjusted OR = 0.8; 95% CI = 0.4-1.6). These data should be considered in the development of a diarrhea vaccine containing only CFAs.
Helicobacter pylori infection is common in the Mexican population; however, sources, routes, and ... more Helicobacter pylori infection is common in the Mexican population; however, sources, routes, and risk factors for infection as well as mode of transmission remain unclear. H. pylori was detected by polymerase chain reaction (PCR) technique in three aquatic systems located in the Mexico City area. In addition, microbiologic cultures and physicochemical parameters were measured. The systems were sampled over an 18-month period (1997-1999), resulting in a total of 212 samples for the different analyses. Twenty-one percent of the samples (16/77) were positive for H. pylori; of these, 42% (5/12) were confirmed for cagA gene detection by PCR hybridization. Microbiologic samples (n = 74) yielded Aeromonas hydrophila, Aeromonas caviae, Aeromonas veronii, and Vibrio fluvialis. In the samples for physicochemical analyses (n = 61), low concentrations of dissolved oxygen were detected and residual chlorine was less than the inactivation dose, both providing conditions for potential survival of H. pylori and other enteric pathogens in these environments. The results of this study suggest that, in Mexico City, water used for human consumption and irrigation may play an important role as a vehicle in the transmission of H. pylori as well as infection by other known enteric pathogens.
Virulence factors of Helicobacter pylori are associated with peptic ulcer disease and may be also... more Virulence factors of Helicobacter pylori are associated with peptic ulcer disease and may be also associated with bleeding peptic ulcers (BPU). To determine whether H. pylori and/or the cytotoxin-associated gene (cagA) can increase the risk of bleeding in peptic ulcers. Sixty-seven patients were studied. Thirty had BPU, 20 had non-bleeding peptic ulcers (NBPU), and 17 were control subjects (NPU). The prevalence of H. pylori was assessed by the urease fast test, histological examination, serology, and 16S ribosomal RNA and cagA gene amplification by polymerase chain reaction (PCR). Histology and PCR showed greater sensitivity for diagnosis of H. pylori under bleeding circumstances when compared with other tests. Association of H. pylori was greater in the NBPU group (odds ratio [OR] 4.91, P = 0.06) than in the BPU group (OR 1.27, P = NS) when compared with the control group. When the BPU and NBPU groups were compared, H. pylori was found more often in the NBPU group (OR 0.26, P < 0.10 ). The cagA-positive gene showed a similar distribution in the three groups. The titres for anti-CagA immunoglobulin A (IgA) antibodies were higher in NBPU patients (83%) than in BPU or control patients. Furthermore, anti-urease immunoglobulin G (IgG) was detected more frequently among BPU and NBPU patients. NBPU patients had the highest prevalence of H. pylori by PCR. It seems unlikely that either H. pylori or the cagA-positive gene act as significant risk factors for bleeding in peptic ulcers. The lower prevalence of the microorganism among patients who bleed cannot be explained as an artificial finding.
The effectiveness of Bacillus Calmette-Guerin (BCG) vaccination in reducing tuberculosis (TB) pre... more The effectiveness of Bacillus Calmette-Guerin (BCG) vaccination in reducing tuberculosis (TB) prevalence rates is poor, resulting in urgent need for improved immunization programs, with new and more effective vaccines against TB. To develop a recombinant Tice BCG vaccine against TB that overexpresses the 38-kDa antigen of Mycobacterium tuberculosis in order to protect against infection by M. tuberculosis H37Rv and hyper-virulent M. tuberculosis Beijing genotype. M. tuberculosis 38-kDa protein was cloned into a mycobacterial shuttle plasmid, which was used to overexpress the 38 kDa protein in BCG Tice to produce the recombinant vaccine, rBCG38 Tice (rBCG38). Compared with BCG Tice, which conferred little protection against the Beijing strain of M. tuberculosis, vaccination with the rBCG38 increased survival of mice infected with either M. tuberculosis H37Rv or a Beijing strain of M. tuberculosis, isolate 9501000. Vaccination with either BCG Tice or rBCG38 resulted in enhanced protection against mycobacterial growth in lung tissue by reducing the number of colony-forming units (CFU). The vaccine induced a strong and highly significant Th1 response, shown by the high level of IL-2 and IFN-gamma cytokine producer cells found in the lungs of challenged mice, and an increase in the IgG2a:IgG1 ratio found in the pooled sera of the vaccinated mice. This study showed that rBCG38 vaccine induced a strong Th1 response, demonstrated by the high levels of IL-2 and IFN-gamma producer cells and IgG2a. Protection was mediated for as long as 6 and 4 months after challenge with M. tuberculosis H37Rv and Beijing genotypes, respectively.
Campylobacter jjuni is an important cause of diarrhea in humans throughout the world [1-3]. It is... more Campylobacter jjuni is an important cause of diarrhea in humans throughout the world [1-3]. It is capable of in-testinal invasion [4, 5], but also, C. jejuni can induce a secretory diarrhea such as that caused by enterotoxin-producing organisms, especially in children [2]. Our find- ...
ABSTRACT The susceptibility to 14 beta-lactam and non-beta-lactam antimicrobial agents was evalua... more ABSTRACT The susceptibility to 14 beta-lactam and non-beta-lactam antimicrobial agents was evaluated for Streptococcus pneumoniae from patients with community-acquired respiratory infections in a Mexican medical center. Three hundred fifteen pneumococcal isolates obtained from patients between 1995 and 2001 were tested by the broth microdilution test. Fifty-two percent of the isolates were nonsusceptible to penicillin (minimal inhibitory concentration, >0.06 microg/mL). Penicillin-nonsusceptible isolates were more likely to exhibit resistance to cephalosporins, macrolides, ciprofloxacin, trimethoprim/sulfamethoxazole, chloramphenicol, and tetracycline when compared to penicillin-susceptible isolates. Ninety-three percent of the penicillin-nonsusceptible isolates were resistant to at least one other class of antimicrobials, in contrast to only 47% of the penicillin-susceptible strains (p < 0.0001). More than 90% of the tested isolates were susceptible to amoxicillin/clavulanate, ceftriaxone, levofloxacin, and gatifloxacin. Reduced susceptibility to penicillin was considered to be a reliable marker for the higher probability of multidrug resistance, thus requiring in vitro tests to guide chemotherapy or the choices of parenteral extended spectrum cephalosporins or newer respiratory quinolones.
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