Elvira Garza-González

Role of the polymorphic IL‐1B, IL‐1RN and TNF‐A genes in distal gastric cancer in Mexico

Several cytokine gene polymorphisms have been associated with increased risk of distal gastric cancer (GC) and its precursor histological markers in Caucasian, Asian and Portuguese populations although little is known about their role in other ethnic groups. Our study investigates the role of the IL‐1B‐31, IL‐1RN and TNF‐A‐308 gene polymorphisms as risk factors for the development of GC in a Mexican population. We studied 278 patients who were enrolled at the Hospital Universitario Dr. José Eleuterio González, Universidad Autónoma de Nuevo León. The subjects were divided into 2 groups. Sixty‐three patients with histologically confirmed distal GC (mean age = 58.8 years, range = 22–84, F:M = 0.56), and 215 patients with no evidence of distal or proximal GC (mean age = 56.1 years, range = 18–92, F:M = 1.17). The IL‐1B‐31 and the TNF‐A‐308 polymorphisms were determined by PCR‐RFLP and pyrosequencing, respectively, in all cases and controls. The VNTR polymorphism in intron 2 of the 1L‐1RN gene was typed by PCR in 25 cases and 201 controls. The H. pylori status was determined by histology, rapid urease test, culture and serology for non‐cancer controls and by histology for the GC cases. The carriage of the proinflammatory IL‐1B‐31*C allele was associated with increased risk of distal GC (odds ratio [OR] = 7.63, 95% confidence interval [CI] = 1.73‐46.94, p = 0.003). When cases and controls were matched by age and gender, the OR value was higher (OR = 8.05, 95% CI = 1.8–50.22, p = 0.001). When only H. pylori GC cases and controls were compared, the OR value was 7.8 (95% CI = 1.05–161.8, p = 0.04). No association was found between any of the other polymorphisms studied and distal GC. In this Mexican population, the IL‐1B proinflammatory genotype increases the risk of distal GC. These findings are similar to previous reports in Caucasian populations and underscore the importance of cytokine gene polymorphisms in the development of distal GC.

Assessment of the toll-like receptor 4 Asp299Gly, Thr399Ile and interleukin-8 -251 polymorphisms in the risk for the development of distal gastric cancer

BackgroundThe intensity of the inflammation induced by Helicobacter pylori colonization is associated with the development of distal gastric cancer (GC). The host response to H. pylori has been related to genetic polymorphisms that influence both innate and adaptive immune responses.Our aim was to investigate whether the presence of the TLR4 Asp299Gly, TLR4 Thr399Ile and IL-8-251 A/T polymorphisms had any influence in the development of distal GC in a Mexican population.MethodsWe studied 337 patients that were divided in two groups: 78 patients with histologically confirmed distal GC and 259 non-cancer controls. The presence of H. pylori in the control population was defined by positive results of at least two of four diagnostic tests: serology, histology, rapid urease test and culture. Human DNA was purified and genotyped for TLR4 Asp299Gly polymorphism by pyrosequencing, for TLR4 Thr399Ile by PCR-RFLP and for IL8-251 by the amplification refractory mutation system (ARMS)-PCR.ResultsThe non-cancer control group was found to be in Hardy-Weinberg equilibrium at the polymorphic loci studied (chi-square H-W = 0.58 for IL8-251, 0.42 for TLR4 Asp299Gly and 0.17 for TLR4 Thr399Ile). The frequencies of mutated alleles (homozygous plus heterozygous) were compared between cases and controls. We found no significant difference for TLR4- Asp299Gly [the 7.7% of distal GC patients and 7.7 % non-cancer controls (p = 0.82)] and for TLR4 Thr399Ile [the 1.3% of GC patients and the 5% of the control population (p = 0.2)]. In contrast, for IL-8-251 A/T, 80.77% of the GC patients and 66.4% in the control group age and gender matched had at least one copy of mutated allele (OR = 2.12, 95% CI = 1.1–4.2) (p = 0.023).ConclusionThis study showed that the IL8-251*A allele could be related to the development of distal gastric cancer in this Mexican population.

A review of Helicobacter pylori diagnosis, treatment, and methods to detect eradication

Helicobacter pylori (H. pylori) affects nearly half of the worlds population and, thus, is one of the most frequent and persistent bacterial infections worldwide. H. pylori is associated with peptic ulcer disease, gastric ulcers, mucosa-associated lymphoid tissue lymphoma, and gastric cancer. Various diagnostic methods exist to detect infection, and the choice of one method or another depends on several factors, such as accessibility, advantages and disadvantages of each method, cost, and the age of patients. Once H. pylori infection is diagnosed, the clinician decides whether treatment is necessity, according to the patients clinical condition. Typically, eradication of H. pylori is recommended for treatment and prevention of the infection. Cure rates with the standard triple therapy are acceptable, and effective quadruple therapies, sequential therapies, and concomitant therapies have been introduced as key alternatives to treat H. pylori infection. In this work, we review the main diagnostic methods used to identify H. pylori infection and to confirm eradication of infection. In addition, key factors related to treatment are reviewed.

Role of p53 codon 72 polymorphism in the risk of development of distal gastric cancer

Objective Mutations in the codon 72 of exon 4 in the p53 gene have been associated with higher risk in the development of several types of cancer. This polymorphism occurs with two alleles encoding either arginine (CGC) or proline (CCC). The aim of this study was to assess the role of the codon 72 polymorphism of p53 in the risk for the development of distal gastric cancer (GC) in a Mexican population. Material and methods We studied 247 patients who were enrolled at the Servicio de Gastroenterología, Hospital Universitario “Dr. José Eleuterio González” Universidad Autónoma de Nuevo León. The study group included 65 distal GC cases [mean age, 58.2 (22–84), median=60, F:M=0.6] and 182 patients without evidence of GC [mean age 53.9 (18–89), median=53, F:M=1.07) as the control group. The polymorphism in the codon 72 of the p53 gene was determined by PCR-RFLP in all the patients. Results As expected, the majority of GC patients were old male. We found a previously unknown association of the Arg/Arg genotype and distal GC (OR: 1.96, 95% confidence interval [CI]=1.06–3.61, p=0.03). Because of age and gender differences, cases and controls were matched in those two variables and the association of Arg/Arg genotype with distal GC persisted (OR: 2.29, 95% CI=1.22–4.32, p=0.01). When cases and controls were matched by age, gender, H. pylori positivity and excluding patients with atrophic gastritis and/or intestinal metaplasia (n=97) the association was stronger (OR: 2.37, 95% CI=1.18–4.77, p=0.01). Conclusions The results of this study suggest that the carriage of the Arg/Arg genotype could be associated with the development of distal GC in this Mexican population.

Molecular characterization and antimicrobial susceptibility of extended-spectrum b-lactamase- producing Enterobacteriaceae isolates at a tertiary- care centre in Monterrey, Mexico

Our objective was to analyse phenotypic and genetic data of extended-spectrum β-lactamase (ESBL)-producing Klebsiella pneumoniae, Enterobacter cloacae, Escherichia coli and Serratia marcescens that cause infections in our hospital. Over a 3 year period, 342 randomly selected clinical Enterobacteriaceae isolates were tested for ESBL production and evaluated for the presence of the β-lactamase genes bla(SHV), bla(TEM,) bla(CTX-M) and bla(TLA-1). The antibiotic susceptibilities of these isolates were also determined, and the clonality of the isolates was assessed by PFGE. Based on our analyses, 33/92 (35.9 %) K. pneumoniae, 31/87 (35.6 %) Enterobacter cloacae, 24/80 (30 %) E. coli and 17/83 (20.5 %) S. marcescens were identified as ESBL producers. The presence of TEM, SHV or CTX ESBL types was detected in 99/105 (94 %) of the isolates. TLA-1 was not detected in any of the 105 isolates. The dominant ESBL types were bla(SHV-5) (n=33), bla(SHV12) (n=31) and bla(CTX-M-15) (n=30). The predominant ESBL identified in E. coli and Enterobacter cloacae isolates was CTX-M-15, whereas in K. pneumoniae and S. marcescens the predominant types were SHV-12 and SHV-5, respectively. PFGE genotyping revealed two main genetic patterns in the K. pneumoniae isolates, types SHV-12 and TEM-1+SHV-5. An outbreak caused by Enterobacter cloacae SHV-5+CTX-M-15 was detected. In contrast, most ESBL-producing isolates of E. coli and S. marcescens did not have similar PFGE banding patterns and thus were not genetically similar. Enterobacteriaceae are a concern in our hospital, especially K. pneumoniae and Enterobacter cloacae. Our results confirm that the CTX-M-15 ESBL type has spread rapidly in the hospital, and thus requires careful monitoring.

Staphylococcal cassette chromosome mec (SCC mec) in methicillin-resistant coagulase-negative staphylococci. A review and the experience in a tertiary-care setting.

Coagulase-negative staphylococci (CNS) are increasingly recognized to cause clinically significant infections, with S. epidermidis often cited as the third most common cause of nosocomial sepsis. Among CNS, there is a high prevalence of methicillin resistance associated with staphylococcal cassette chromosome (SCCmec) elements. Although identical SCCmec types can exist in S. aureus and CNS, some novel classes of SCCmec may be unique to CNS. Differences in the accuracy of identification of CNS species and use of non-standardized methods for the detection of methicillin resistance have led to confusing data in the literature. In addition to the review of SCCmec in CNS, in this paper we report a 2-year surveillance of methicillin-resistant CNS in a tertiary-care hospital in Guadalajara, Mexico.

Association of IL1B -511C/-31T haplotype and Helicobacter pylori vacA genotypes with gastric ulcer and chronic gastritis

BackgroundThe association between proinflammatory cytokine gene polymorphisms and gastric diseases related to Helicobacter pylori varies by population and geographic area.Our objective was to determine if the IL-1B -511 T>C and -31 C>T polymorphisms and H. pylori vacA genotypes are associated with risk of chronic gastritis and gastric ulcer in a Mexican population.MethodsWe conducted endoscopic studies in 128 patients with symptoms of dyspepsia. We took two biopsies from the body, antrum, or ulcer edge from each patient, and classified our histopathological findings according to the Sydney System. H. pylori infection and vacA genotyping were accomplished via PCR from total DNA of the gastric biopsies. We confirmed the presence of anti-H. pylori serum IgG and IgM in 102 control subjects. In both case subjects and control subjects, the IL-1B -511 T>C polymorphism was genotyped by PCR-RFLPs and the IL-1B -31 C>T polymorphism was genotyped by pyrosequencing.ResultsSixty-two point seven (62.7%) of the 102 control subjects were H. pylori-seropositive. Among the case subjects, 100 were diagnosed with chronic gastritis and 28 with gastric ulcer. We found that 77% of the patients with chronic gastritis and 85.7% of the patients with gastric ulcer were H. pylori-positive. The predominant H. pylori genotype was vacA s1m1 (58.4%) and the most frequent subtype was vacA s1. The -511 TC, (rs16944 -511 T>C) genotype and the -511C allele were associated with chronic gastritis (OR = 3.1, 95% CI = 1.4-6.8 and OR = 3.0, 95% CI = 1.4-6.0, respectively). The subjects carrying -31T (rs1143627 -31 C>T) were found to be at a higher risk of having chronic gastritis (OR = 2.8, 95% CI = 1.3-5.8). The IL-1B -511C/-31T haplotype was associated with chronic gastritis (OR = 2.1, 95% CI = 1.2-3.8) but not with gastric ulcer.ConclusionsThe H. pylori vacA genotypes identified herein were similar to those reported for other regions of Mexico. The vacA s1m1 genotype was not associated with gastric ulcer. In the southern Mexican population, the IL-1B -511C and -31T alleles and the -511C/-31T and -511T/-31T haplotypes are associated with increased risk of chronic gastritis and gastric ulcer.

Chemical Composition of Hexane Extract of Citrus aurantifolia and Anti-Mycobacterium tuberculosis Activity of Some of Its Constituents

The main aim of this study was to isolate and characterize the active compounds from the hexane extract of the fruit peels of Citrus aurantiifolia, which showed activity against one sensitive and three monoresistant (isoniazid, streptomycin or ethambutol) strains of Mycobacterium tuberculosis H37Rv. The active extract was fractionated by column chromatography, yielding the following major compounds: 5-geranyloxypsoralen (1); 5-geranyloxy-7-methoxycoumarin (2); 5,7-dimethoxycoumarin (3); 5-methoxypsoralen (4); and 5,8-dimethoxypsoralen (5). The structures of these compounds were elucidated by 1D and 2D NMR spectroscopy. In addition, GC-MS analysis of the hexane extract allowed the identification of 44 volatile compounds, being 5,7-dimethoxycoumarin (15.79%), 3-methyl-1,2-cyclopentanedione (8.27%), 1-methoxy-ciclohexene (8.0%), corylone (6.93%), palmitic acid (6.89%), 5,8-dimethoxypsoralen (6.08%), α-terpineol (5.97%), and umbelliferone (4.36%), the major constituents. Four isolated coumarins and 16 commercial compounds identified by GC-MS were tested against M. tuberculosis H37Rv and three multidrug-resistant M. tuberculosis strains using the Microplate Alamar Blue Assay. The constituents that showed activity against all strains were 5 (MICs = 25–50 μg/mL), 1 (MICs = 50–100 μg/mL), palmitic acid (MICs = 25–50 μg/mL), linoleic acid (MICs = 50–100 μg/mL), oleic acid (MICs = 100 μg/mL), 4-hexen-3-one (MICs = 50–100 μg/mL), and citral (MICs = 50–100 μg/mL). Compound 5 and palmitic acid were the most active ones. The antimycobacterial activity of the hexane extract of C. aurantifolia could be attributed to these compounds.

Antibacterial and Antimycobacterial Lignans and Flavonoids from Larrea tridentata

Three lignans and four flavonoids were isolated and characterized from Larrea tridentata and compounds were tested against 16 bacterial species/strains. Results showed that: dihydroguaiaretic acid (1) had activity towards methicillin resistant (MR) Staphylococcus aureus (minimum inhibitory concentration (MIC) 50 µg/mL) and multidrug‐resistant (MDR) strains of Mycobacterium tuberculosis (MIC 12.5–50 µg/mL); 4‐epi‐larreatricin (2) was active against Enterobacter cloacae (MIC 12.5 µg/mL), as well as sensitive (MIC 50 µg/mL) and MDR strains of M. tuberculosis (MIC 25 µg/mL). 3′‐Demethoxy‐6‐O‐demethylisoguaiacin (3) displayed activity against sensitive and resistant S. aureus (MIC 25 µg/mL), Enterococcus faecalis (MIC 12.5 µg/mL), Escherichia coli (MIC 50 µg/mL), E. cloacae (MIC 12.5 µg/mL) and MDR strains of M. tuberculosis (MIC 12.5 µg/mL). 5,4′‐Dihydroxy‐3,7,8,3′‐tetramethoxyflavone (4) and 5,4′‐dihydroxy‐3,7,8‐trimethoxyflavone (5) were active against M. tuberculosis MDR strains having MIC values of 25 and 25–50 µg/mL, respectively, while 5,4′‐dihydroxy‐7‐methoxyflavone (6) was active against S. aureus (MIC 50 µg/mL) and E. faecalis (MIC 50 µg/mL). We concluded that lignan 3 is the main compound responsible for the antibacterial activity of L. tridentata. Lignans 1 and 2 as well as flavonoid 6 contribute with some degree of antibacterial activity. On the other hand, compounds 1, 2, 3, 4 and 5 contributed to the antimycobacterial activity found in L. tridentata. Copyright

Prevalence of Multidrug-Resistant Bacteria at a Tertiary-Care Teaching Hospital in Mexico: Special Focus on Acinetobacter baumannii

Our aim was to determine the prevalence of multidrug resistance of Acinetobacter baumannii and other pathogens at a tertiary-care teaching hospital in Mexico over a 3-year period. Clinical isolates of A. baumannii (n = 550), Pseudomonas aeruginosa (n = 250), some Enterobacteriaceae species (n = 500) and Staphylococcus aureus (n = 250) collected over a 3-year period were included. Susceptibility tests were performed by the broth microdilution method. 74% of A. baumannii, 40% of Escherichia coli, 34% of P. aeruginosa, 22% of Klebsiella pneumoniae, 9% of Enterobacter cloacae, and 7% of Serratia sp. were multidrug resistant. 59% of A. baumannii clinical isolates were meropenem-resistant. A. baumannii isolates from the lower respiratory tract were the most susceptible, followed by urine clinical isolates. Species from Enterobacteriaceae showed susceptibility rates higher than 90% to meropenem and tigecycline and Serratia sp. showed the highest susceptibility to the drugs evaluated. For P. aeruginosa, the most potent drug was levofloxacin, followed by meropenem and piperacillin-tazobactam. With regard to S. aureus, 96% of the isolates were susceptible to vancomycin, followed by tigecycline and minocycline (91% of strains susceptible). The high multidrug resistance observed underscores the need for surveillance of bacterial drug resistance.