Distribution and virulence of Escherichia coli harboring cyclomodulins and supplementary virulence genes isolates from clinical and environmental samples.

This study aimed to determine the prevalence of cyclomodulins (cdt, cnf, pks and cif) in Escherichia coli (E. coli) isolated from clinical and environmental samples, the presence of supplementary virulence genes (SVG), antibiotic resistance, and in vitro cytotoxicity. 413 E. coli were isolated from clinical (stool from obese subjects, normal weight subjects, children with diarrhea, and children without diarrhea; and urine from pregnant and non-pregnant women with urinary tract infections) and environmental (water and different foods) samples. PCR was performed to identify E. coli pathotypes, the four cyclomodulins, and 18 SVG; virulence score, cytotoxic assay, and antibiotic resistance assay were performed. Fifteen percent of E. coli were positive for cyclomodulins and were found in all isolation sources; however, in children with diarrhea, they were more frequent. The most frequent cyclomodulin was cdt. More DEC strains harbor cyclomodulins than non-DEC, and cyclomodulins were most frequent among aEPEC pathotype. SVG ehaC was associated with cyclomodulin-positive strains. Cyclomodulin-positive E. coli had a higher virulence score but no significant cytotoxic activity. They were slightly more resistant to antibiotics. In conclusion, cyclomodulins-positive E. coli was widely distributed in humans, food, and the environment, and they were associated with SVG ehaC, suggesting that these genes may play a role in the pathogenesis of the cyclomodulins. However, more research is needed.

Virulence genes, antimicrobial resistance profile, phylotyping and pathotyping of diarrheagenic Escherichia coli isolated from children in Southwest Mexico.

Diarrheagenic E. coli (DEC) strains are one of the most important etiology factors causing diarrhea in children worldwide, especially in developing countries. DEC strains have characteristic virulence factors; however, other supplemental virulence genes (SVG) may contribute to the development of diarrhea in children. Therefore, this study aimed to determine the prevalence of DEC in children with diarrhea in southwestern Mexico and to associate childhood symptoms, SVG, and pathotypes with diarrhea-causing DEC strains. DEC strains were isolated from 230 children with diarrhea aged 0-60 months from the state of Oaxaca, southwestern Mexico; clinical data were collected, and PCR was used to identify SVG and pathotypes. Antibiotic resistance profiling was performed on DEC strains. 63% of samples were DEC positive, single or combined infections (two (21%) or three strains (1.3%)) of aEPEC (51%), EAEC (10.2%), tEPEC (5.4%), DAEC (4.8%), ETEC (4.1%), EIEC (1.4%), or EHEC (0.7%) were found. Children aged ≤ 12 and 49-60 months and symptoms (e.g., fever and blood) were associated with DEC strains. SVG related to colonization (nleB-EHEC), cytotoxicity (sat-DAEC and espC-tEPEC), and proteolysis (pic-aEPEC) were associated with DECs strains. E. coli phylogroup A was the most frequent, and some pathotypes (aEPEC-A, DAEC-B), and SVG (espC-B2, and sat-D) were associated with the phylogroups. Over 79% of the DEC strains were resistant to antibiotics, and 40% were MDR and XDR, respectively. In conclusion aEPEC was the most prevalent pathotype in children with diarrhea in this region. SVG related to colonization, cytotoxicity, and proteolysis were associated with diarrhea-producing DEC strains, which may play an essential role in the development of diarrhea in children in southwestern Mexico.

Outbreak of Serratia marcescens in the Neonatal Intensive Care Unit of a Tertiary Care Hospital in Mexico.

Introduction: We describe an outbreak of Serratia marcescens (S. marcescens) infection in the neonatal intensive care unit at Women's Hospital in Sinaloa, Mexico. Methods: In April 2021, an outbreak of S. marcescens infection was identified. A case was identified as any patient who tested positive for S. marcescens and showed signs of an infectious process. Results: S. marcescens was isolated from the blood cultures of 15 neonates with clinical signs of neonatal sepsis. Statistical analysis showed that all neonates had an invasive medical device. The problem was controlled after hospital hygiene and sanitation measures were strengthened. Conclusion: The study provides evidence of an outbreak of nosocomial bacteremia due to the cross-transmission of S. marcescens. The findings highlight the need for hospitals to implement strict hygiene measures, especially regarding hand washing, to prevent future outbreaks.

Virulence-associated genes and antimicrobial resistance patterns in bacteria isolated from pregnant and nonpregnant women with urinary tract infections: the risk of neonatal sepsis.

Uropathogenic Escherichia coli (UPEC) is classified as the major causative agent of urinary tract infections (UTIs). UPEC virulence and antibiotic resistance can lead to complications in pregnant women and (or) newborns. Therefore, the aim of this study was to determine the etiological agents of UTIs, as well as to identify genes related to virulence factors in bacteria isolated from pregnant and nonpregnant women. A total of 4506 urine samples were collected from pregnant and nonpregnant women. Urine cultures were performed, and PCR was used to identify phylogroups and virulence-related genes. Antibiotic resistance profiles were determined. The incidence of UTIs was 6.9% (pregnant women, n = 206 and nonpregnant women, n = 57), and UPEC belonging to phylogroup A was the most prevalent. The presence of genes related to capsular protection, adhesins, iron acquisition, and serum protection in UPEC was associated with not being pregnant, while the presence of genes related to adhesins was associated with pregnancy. Bacteria isolated from nonpregnant women were more resistant to antibiotics; 36.5% were multidrug resistant, and 34.9% were extensively drug resistant. Finally, UTIs were associated with neonatal sepsis risk, particularly in pregnant women who underwent cesarean section while having a UTI caused by E. coli. In conclusion, UPEC isolated from nonpregnant women carried more virulence factors than those isolated from pregnant women, and maternal UTIs were associated with neonatal sepsis risk.

Association of PCSK1 and PPARG1 Allelic Variants with Obesity and Metabolic Syndrome in Mexican Adults.

Metabolic diseases, including obesity, diabetes, and metabolic syndrome, are among the most important public health challenges worldwide. Metabolic diseases are classified as multifactorial diseases in which genetic variants such as single-nucleotide polymorphisms (SNPs) may play an important role. The present study aimed to identify associations linking allelic variants of the PCSK1, TMEM18, GPX5, ZPR1, ZBTB16, and PPARG1 genes with anthropometric and biochemical traits and metabolic diseases (obesity or metabolic syndrome) in an adult population from northwestern Mexico. METHODS: Blood samples were collected from 523 subjects, including 247 with normal weight, 276 with obesity, and 147 with metabolic syndrome. Anthropometric and biochemical characteristics were recorded, and single-nucleotide polymorphisms (SNPs) were genotyped by real-time PCR. RESULTS: PCSK1 was significantly (p < 0.05) associated with BMI, weight, and waist-to-hip ratio; TMEM18 was significantly associated with systolic blood pressure and triglyceride levels; GPX5 was significantly associated with HDL cholesterol levels. In addition, PCSK1 was associated with obesity (p = 1.0 × 10-4) and metabolic syndrome (p = 3.0 × 10-3), whereas PPARG1 was associated with obesity (p = 0.044). CONCLUSIONS: The associations found in this study, mainly between allelic variants of PCSK1 and metabolic traits, obesity, and metabolic syndrome, may represent a risk for developing metabolic diseases in adult subjects from northwestern Mexico.

Antitumor activity of bovine lactoferrin and its derived peptides against HepG2 liver cancer cells and Jurkat leukemia cells.

Liver cancer and leukemia are the fourth and first causes, respectively, of cancer death in children and adults worldwide. Moreover, cancer treatments, although beneficial, remain expensive, invasive, toxic, and affect the patient's quality of life. Therefore, new anticancer agents are needed to improve existing agents. Because bovine lactoferrin (bLF) and its derived peptides have antitumor properties, we investigated the anticancer effect of bLF and LF peptides (LFcin17-30, LFampin265-284 and LFchimera) on liver cancer HepG2 cells and leukemia Jurkat cells. HepG2 and Jurkat cells were incubated with bLF and LF peptides. Cell proliferation was quantified by an MTT assay, and cell morphology and damage were visualized by light microscopy or by phalloidin-TRITC/DAPI staining. The discrimination between apoptosis/necrosis was performed by staining with Annexin V-Alexa Fluor 488 and propidium iodide, and the expression of genes related to apoptosis was analyzed in Jurkat cells. Finally, the synergistic interaction of bLF and LF peptides with cisplatin or etoposide was assessed by an MTT assay and the combination index. The present study demonstrated that bLF and LF peptides inhibited the viability of HepG2 and Jurkat cells, inducing damage to the cell monolayer of HepG2 cells and morphological changes in both cell lines. bLF, LFcin17-30, and LFampin265-284 triggered apoptosis in both cell lines, whereas LFchimera induced necrosis. These results suggested that bLF and LF peptides activate apoptosis by increasing the expression of genes of the intrinsic pathway. Additionally, bLF and LF peptides synergistically interacted with cisplatin and etoposide. In conclusion, bLF and LF peptides display anticancer activity against liver cancer and leukemia cells, representing an alternative or improvement in cancer treatment.

Vibrio parahaemolyticus Is Associated with Diarrhea Cases in Mexico, with a Dominance of Pandemic O3:K6 Clones.

In the present study, we conducted surveillance of the V. parahaemolyticus strains present in clinical samples from six geographical regions of Mexico (22 states) from 2004 to 2011. The serotype dominance, virulence genes, presence of pandemic O3:K6 strains, and antibiotic resistance of the isolates were investigated. In total, 144 strains were isolated from the clinical samples. Seven different O serogroups and twenty-five serovars were identified. Most clinical isolates (66%, 95/144) belonged to the pandemic clone O3:K6 (tdh+, toxRS/new+ and/or orf8+) and were detected in 20 of the 22 states. Among the pandemic clones, approximately 17.8% (17/95) of the strains cross-reacted with the antisera for the K6 and K59 antigens (O3:K6, K59 serotype). Other pathogenic strains (tdh+ and/or trh+, toxRS/new-, orf8-) accounted for 26.3%, and the nonpathogenic strains (tdh- and/or trh-) accounted for 7.6%. Antimicrobial susceptibility testing showed that most of the strains were resistant to ampicillin (99.3%) but were sensitive to most tested antibiotics. The level of multidrug resistance was 1.3%. Our results indicate that pandemic O3:K6 is present in most Mexican states, thus, constant surveillance of V. parahaemolyticus strains in diarrhea patients is a public health priority and is useful for conducting risk assessments of foodborne illnesses to prevent V. parahaemolyticus outbreaks. Overall, our observations indicate that the pandemic O3:K6 clone of V. parahaemolyticus has become a relatively stable subpopulation and may be endemically established in Mexico; therefore, constant surveillance is needed to avoid new outbreaks of this pathogen.

ISOLATION, CHARACTERIZATION, AND ANTIMICROBIAL SUSCEPTIBILITY OF BACTERIA ISOLATED FROM SEA LION (ZALOPHUS CALIFORNIANUS) PUPS IN NORTHWESTERN MEXICO.

Bacterial infections have been documented in marine mammals for decades, and some are considered emerging pathogens with zoonotic potential. The aerobic oral (n=16) and rectal (n=17) bacterial microbiota and their antimicrobial resistance were characterized for 17 apparently healthy California sea lion pups (Zalophus californianus) captured with a hoop net in Farallon Island, Sinaloa, Mexico, in 2016. Bacteriologic cultures, Analytical Profile Index, and PCR were used to identify bacterial species. The Escherichia coli phylogenetic groups were identified by PCR, Salmonella serotypes were identified, and resistance to antibiotics was evaluated. Overall, 39 bacterial species were isolated, including E. coli and Salmonella spp. (35.9% each) and Pseudomonas aeruginosa (28.2%). For E. coli, UNKNOWN phylogroup was the most prevalent (57.7%), followed by the A phylogroup (37.1%). Most Salmonella serotypes were identified as Newport (92.8%); serotype Saintpaul was also identified (7.2%). Sea lions with bacterial co-colonization included 24.2%, from which two bacterial species were isolated, and 3% with three species. Overall, 59% of bacteria were resistant to at least one antibiotic tested, and 25.6% were extensively drug resistant. Bacteria were highly resistant to ampicillin and cefotaxime. This study demonstrates the importance of characterizing the microbiome of sea lions, and the potential effect of pathogens with antimicrobial resistance on wildlife conservation and public health.

Epidemiological and clinical characteristics of pregnant women and neonates with COVID-19 in Northwest Mexico.

INTRODUCTION: The SARS-CoV-2 virus, which causes COVID-19, has spread quickly worldwide, causing millions of cases and thousands of deaths. Some risk factors in the general population are related to the development of severe COVID-19 or death, but in pregnant women and neonates, the information is limited. OBJECTIVE: To determine the epidemiological and clinical characteristics of pregnant women and neonates diagnosed with COVID-19 by RT-PCR and serological tests, and analyze the relationship between the influenza vaccination and COVID-19 symptoms in infected pregnant women in Sinaloa state. METHODS: We collected samples from 116 pregnant women and 84 neonates from the Women´s Hospital of Sinaloa. They were diagnosed with COVID-19 by RT-PCR and serological tests (IgG), and sociodemographic, clinical and laboratory parameters were recorded. RESULTS: A total of 11.2% (13/116) of the pregnant women were RT-PCR+, 25% (29/116) were IgG+ and 4.3% (5/116) were positive for both tests. Symptoms such as rhinorrhea (P = .04), cough (P = .02) and polypnea (P = .04) in pregnant women were related to COVID-19, also leukocyte index was higher in pregnant women with COVID-19 (P = .03), but the associations were lost after the Bonferroni correction. No laboratory parameters or underlying diseases were associated with COVID-19, and most infected pregnant women had mild cases. We found an association between the influenza vaccine and less common COVID-19 symptoms in pregnant women who were infected (P = .01). A total of 7.2% (6/84) of neonates were RT-PCR+, 35.7% (30/84) were IgG+, and there were no symptoms or underlying diseases associated with neonates who were infected. In conclusion, this work demonstrated that some symptoms were related to COVID-19, most pregnant women and neonates had mild cases, and the influenza vaccine could decrease the severity of COVID-19 cases in pregnant women.

Association of FTO, ABCA1, ADRB3, and PPARG variants with obesity, type 2 diabetes, and metabolic syndrome in a Northwest Mexican adult population.

AIM: To identify associations among allelic variants of the genes FTO, ABCA1, ADRB3, and PPARG with anthropometric and biochemical traits, metabolic diseases (obesity, T2D or metabolic syndrome) in an adult population from Northwest Mexico. METHODS: Blood samples were collected from 846 subjects including 266 normal weight subjects, 285 with obesity, and 295 with T2D. Of the 846 persons in the study, 365 presented metabolic syndrome diagnostic criteria. Anthropometric and biochemical traits were recorded and 4 single nucleotide polymorphisms (SNPs): FTO rs9939609 A-allele, ABCA1 rs9282541 A-allele, ADRB3 rs4994 G-allele, and PPARG rs1801282 G-allele were genotyped by real-time PCR. RESULTS: FTO rs9939609 A-allele was significantly associated with obesity (p: 8.3 × 10-4), and metabolic syndrome (p: 0.001), but no individual SNPs were significantly associated with T2D. Finally, the cumulative risk of the four SNPs was significantly associated with obesity (p: 1.95 × 10-4). CONCLUSION: Associations in FTO, ABCA, ADRB3, and PPARG SNPs presented in this study with obesity and metabolic syndrome could represent a risk for developing metabolic diseases in Northwest Mexican adult subjects.

Non-diarrheagenic and diarrheagenic E. coli carrying supplementary virulence genes (SVG) are associated with diarrhea in children from Mexico.

Escherichia coli strains, including diarrheagenic E. coli (DEC), are among the most important causes of childhood diarrhea in developing countries. Since these strains also colonize healthy children, additional factors leading to diarrhea remains to be discovered. We therefore conducted a comprehensive study to investigate if supplementary virulence genes (SVG) carried by DEC strains and non-DEC strains, contribute to diarrhea in Mexican children. E. coli strains were isolated from n = 317 children between 6 and 12 years, n = 114 with diarrhea and n = 203 asymptomatic children from Northwestern Mexico, PCR was used to identify SVG, then virulence score and cytotoxic assay in HT-29 cells were performed to evaluate virulence of E. coli strains. DEC prevalence was 18.6% and its presence was significantly associated with diarrhea cases. aEPEC, tEAEC, ETEC, DAEC, aEAEC, tEPEC, and EIEC pathotypes were identified. aEPEC strains were significantly associated with asymptomatic children, whereas ETEC was only identified in children with diarrhea. E. coli strains carrying colonization-related SVG and/or proteolysis-related SVG were significantly associated with diarrhea. DEC strains were associated to diarrhea if strains carried SVG ehaC, kps, nleB, and/or espC. Virulence score was significantly higher in E. coli from diarrhea cases than asymptomatic. In addition, DEC strains carrying SVG+ were more virulent, followed by non-DEC SVG+ strains, and correlated with the cytotoxicity assay. Nearly 50% of DEC strains were MDR, and ~10% were XDR. In conclusion the findings of this work provide evidence that the presence of E. coli strains (regardless if strains are DEC or non-DEC) with SVG were associated with diarrhea in Mexican children.

Analysis of Epidemiological and Clinical Characteristics of COVID-19 in Northwest Mexico and the Relationship Between the Influenza Vaccine and the Survival of Infected Patients.

The first cases of unexplained pneumonia were reported in Wuhan, China, in December of 2019. Later, a novel coronavirus (SARS-CoV-2) was identified as the causal agent of pneumonia. This virus has since spread to more than 180 countries and has been declared a pandemic by the World Health Organization. Herein, we aimed to determine the epidemiological and clinical characteristics of symptomatic patients with coronavirus disease 2019 (COVID-19) and the relationship between the influenza vaccine with a lower risk of severe COVID-19 infection in the state of Sinaloa. We collected demographic and clinical data of 4,040 patients with acute respiratory infections across Sinaloa state hospitals from February 28 to May 15, 2020. The prevalence of COVID-19 among hospitalized patients with respiratory symptoms in Sinaloa showed 45.2% of men were more affected than women (p < 0.001), and people aged 40-49 years were the most affected. The main symptoms of COVID-19 infection were cough and fever (p < 0.001), while hypertension, obesity, and type 2 diabetes were the chronic diseases associated with COVID-19 than non-COVID-19 (p < 0.003). Healthcare workers were most likely to be infected compared to other occupations (p < 0.001). The general lethality rate was 14.1%, and males >62 years were the ones who had a higher lethality rate (p < 0.001); the aforementioned chronic diseases were related to higher lethality of COVID-19 (p < 0.001). Likewise, higher lethality was seen in housewives and patient retirees/pensioners compared with other occupations (p < 0.001). Finally, we found there was a relationship between influenza vaccination and a lower risk of severe COVID-19 infection and mortality (p < 0.001). These findings showed that healthcare workers, men >62 years with chronic diseases, and retired people were most affected. Furthermore, the influenza vaccine could decrease the severeness of COVID-19 cases.

Prevalence of Cyclomodulin-Positive E. coli and Klebsiella spp. Strains in Mexican Patients with Colon Diseases and Antimicrobial Resistance.

Colon diseases, such as colorectal cancer (CRC), are multifactor diseases that affect more than one million people per year; recently, the microbiota has been associated with an etiologic factor, specifically bacterial cyclomodulin positivity (CM+). Unfortunately, there are no studies from Mexico that detail the presence of bacterial CM+ in patients with colon diseases. We therefore performed a comprehensive study to investigate the associations and prevalence of cyclomodulin-positive Diarrheagenic E. coli (DEC), non-DEC, and Klebsiella spp. strains isolated from Mexican subjects with colon diseases. In this work, we analyzed 43 biopsies, 87 different bacteria were isolated, and E. coli was the most frequently noted, followed by Klebsiella spp., and Enterococcus spp. E. coli, non-DEC, and EPEC belonging to phylogroup B2 were the most prevalent. More than 80% of E. coli and Klebsiella were CM+. pks, cdt, cnf, and cif were identified. cdt was associated with non-DEC, cif and its combinations with EPEC, as well as cdt and psk with Klebsiella. Lastly, all the CM+ bacteria were resistant to at least one antibiotic (34% were MDR, and 48% XDR). In conclusion, the high prevalence of bacterial CM+ in colon disease patients suggests that these bacteria play an important role in the genesis of these diseases.

Lactoferrin Disaggregates Pneumococcal Biofilms and Inhibits Acquisition of Resistance Through Its DNase Activity.

Streptococcus pneumoniae colonizes the upper airways of children and the elderly. Colonization progresses to persistent carriage when S. pneumoniae forms biofilms, a feature required for the development of pneumococcal disease. Nasopharyngeal biofilms are structured with a matrix that includes extracellular DNA (eDNA), which is sourced from the same pneumococci and other bacteria. This eDNA also allows pneumococci to acquire new traits, including antibiotic resistance genes. In this study, we investigated the efficacy of lactoferrin (LF), at physiological concentrations found in secretions with bactericidal activity [i.e., colostrum (100 µM), tears (25 µM)], in eradicating pneumococcal biofilms from human respiratory cells. The efficacy of synthetic LF-derived peptides was also assessed. We first demonstrated that LF inhibited colonization of S. pneumoniae on human respiratory cells without affecting the viability of planktonic bacteria. LF-derived peptides were, however, bactericidal for planktonic pneumococci but they did not affect viability of pre-formed biofilms. In contrast, LF (40 and 80 µM) eradicated pneumococcal biofilms that had been pre-formed on abiotic surfaces (i.e., polystyrene) and on human pharyngeal cells, as investigated by viable counts and confocal microscopy. LF also eradicated biofilms formed by S. pneumoniae strains with resistance to multiple antibiotics. We investigated whether treatment with LF would affect the biofilm structure by analyzing eDNA. Surprisingly, in pneumococcal biofilms treated with LF, the eDNA was absent in comparison to the untreated control (∼10 µg/ml) or those treated with LF-derived peptides. EMSA assays showed that LF binds S. pneumoniae DNA and a time-course study of DNA decay demonstrated that the DNA is degraded when bound by LF. This LF-associated DNase activity inhibited acquisition of antibiotic resistance genes in both in vitro transformation assays and in a life-like bioreactor system. In conclusion, we demonstrated that LF eradicates pneumococcal-colonizing biofilms at a concentration safe for humans and identified a LF-associated DNAse activity that inhibited the acquisition of resistance.

Interaction between Streptococcus pneumoniae and Staphylococcus aureus Generates ·OH Radicals That Rapidly Kill Staphylococcus aureus Strains.

Streptococcus pneumoniae rapidly kills Staphylococcus aureus by producing membrane-permeable hydrogen peroxide (H2O2). The mechanism by which S. pneumoniae-produced H2O2 mediates S. aureus killing was investigated. An in vitro model that mimicked S. pneumoniae-S. aureus contact during colonization of the nasopharynx demonstrated that S. aureus killing required outcompeting densities of S. pneumoniae Compared to the wild-type strain, isogenic S. pneumoniae ΔlctO and S. pneumoniae ΔspxB, both deficient in production of H2O2, required increased density to kill S. aureus While residual H2O2 activity produced by single mutants was sufficient to eradicate S. aureus, an S. pneumoniae ΔspxB ΔlctO double mutant was unable to kill S. aureus A collection of 20 diverse methicillin-resistant S. aureus (MRSA) and methicillin-susceptible S. aureus (MSSA) strains showed linear sensitivity (R2 = 0.95) for S. pneumoniae killing, but the same strains had different susceptibilities when challenged with pure H2O2 (5 mM). There was no association between the S. aureus clonal complex and sensitivity to either S. pneumoniae or H2O2 To kill S. aureus, S. pneumoniae produced ∼180 µM H2O2 within 4 h of incubation, while the killing-defective S. pneumoniae ΔspxB and S. pneumoniae ΔspxB ΔlctO mutants produced undetectable levels. Remarkably, a sublethal dose (1 mM) of pure H2O2 incubated with S. pneumoniae ΔspxB eradicated diverse S. aureus strains, suggesting that S. pneumoniae bacteria may facilitate conversion of H2O2 to a hydroxyl radical (·OH). Accordingly, S. aureus killing was completely blocked by incubation with scavengers of ·OH radicals, dimethyl sulfoxide (Me2SO), thiourea, or sodium salicylate. The ·OH was detected in S. pneumoniae cells by spin trapping and electron paramagnetic resonance. Therefore, S. pneumoniae produces H2O2, which is rapidly converted to a more potent oxidant, hydroxyl radicals, to rapidly intoxicate S. aureus strains.IMPORTANCEStreptococcus pneumoniae strains produce hydrogen peroxide (H2O2) to kill bacteria in the upper airways, including pathogenic Staphylococcus aureus strains. The targets of S. pneumoniae-produced H2O2 have not been discovered, in part because of a lack of knowledge about the underlying molecular mechanism. We demonstrated that an increased density of S. pneumoniae kills S. aureus by means of H2O2 produced by two enzymes, SpxB and LctO. We discovered that SpxB/LctO-produced H2O2 is converted into a hydroxyl radical (·OH) that rapidly intoxicates and kills S. aureus We successfully inhibited the toxicity of ·OH with three different scavengers and detected ·OH in the supernatant. The target(s) of the hydroxyl radicals represents a new alternative for the development of antimicrobials against S. aureus infections.

Strategies of Vibrio parahaemolyticus to acquire nutritional iron during host colonization.

Iron is an essential element for the growth and development of virtually all living organisms. As iron acquisition is critical for the pathogenesis, a host defense strategy during infection is to sequester iron to restrict the growth of invading pathogens. To counteract this strategy, bacteria such as Vibrio parahaemolyticus have adapted to such an environment by developing mechanisms to obtain iron from human hosts. This review focuses on the multiple strategies employed by V. parahaemolyticus to obtain nutritional iron from host sources. In these strategies are included the use of siderophores and xenosiderophores, proteases and iron-protein receptor. The host sources used by V. parahaemolyticus are the iron-containing proteins transferrin, hemoglobin, and hemin. The implications of iron acquisition systems in the virulence of V. parahaemolyticus are also discussed.

Bactericidal effect of bovine lactoferrin and synthetic peptide lactoferrin chimera in Streptococcus pneumoniae and the decrease in luxS gene expression by lactoferrin.

Streptococcus pneumoniae (pneumococcus) is responsible for nearly one million child deaths annually. Pneumococcus causes infections such as pneumonia, otitis media, meningitis, and sepsis. The human immune system includes antibacterial peptides and proteins such as lactoferrin (LF), but its activity against pneumococcus is not fully understood. The aim of this work was to evaluate the bactericidal effect of bovine lactoferrin (bLF) and the synthetic LF-peptides lactoferricin (LFcin17-30), lactoferrampin (LFampin265-284), and LFchimera against S. pneumoniae planktonic cells. The mechanism of damage was also investigated, as well as the impact of these peptides on the transcription levels of genes known to encode important virulence factors. S. pneumoniae planktonic cells were treated with bLF, LFcin17-30, LFampin265-284 and LFchimera at different time points. The viability of treated planktonic cells was assessed by dilution and plating (in CFU/ml). The interaction between LF and LF-peptides coupled to fluorescein was visualized using a confocal microscope and flow cytometry, whereas the damage at structural levels was observed by electron microscopy. Damage to bacterial membranes was further evaluated by membrane permeabilization by use of propidium iodide and flow cytometry, and finally, the expression of pneumococcal genes was evaluated by qRT-PCR. bLF and LFchimera were the best bactericidal agents. bLF and peptides interacted with bacteria causing changes in the shape and size of the cell and membrane permeabilization. Moreover, the luxS gene was down-regulated in bacteria treated with LF. In conclusion, LF and LFchimera have a bactericidal effect, and LF down-regulates genes involved in the pathogenicity of pneumococcus, thus demonstrating potential as new agents for the treatment of pneumococcal infections.