Influence of lipids and proteins amounts and pH values on the inhibitory effects of Origanum vulgare L. essential oil against Escherichia coli and Salmonella Typhimurium

Origanum vulgare L. (OVEO) essential oil has been considered a candidate antimicrobial for use in food conservation systems. However, studies on the influence of concomitant variations of different food components or physicochemical parameters on the antibacterial properties of OVEO are scarce. This study assessed the influence of concomitant variations in amounts of proteins - PTN (4.0, 6.0 or 8.0 g/100 mL) and lipids - LIP (3.75, 5.0 or 6.25 g/100 mL) and pH values (5.0, 5.5 or 6.0) in cultivation medium on the inhibitory effects of OVEO against Escherichia coli (EC) and Salmonella Typhimurium (ST). Lowest minimum inhibitory concentration values of OVEO against EC and ST were observed in media with the highest LIP amounts regardless the PTN amount and pH value. In absorbance based microtiter plate assay (MPA), for both EC and ST, OVEO caused the lowest Grmax values in medium containing the highest LIP and PTN amounts and lowest pH value. Highest Grmax values for EC and ST were observed in medium containing the lowest LIP and PTN amount and highest pH value. Grmax values estimated from viable counts of EC and ST in tested media with OVEO confirmed bacterial growth behavior similar to that observed in MPA. Overall, the LIP amount in media was as the most influential factor to enhance the antibacterial effects of OVEO. These results indicate that the concomitant influence of LIP and PTN amounts and pH values on the antibacterial effects of OVEO should be considered for optimizing its antimicrobial efficacy in foods.

Enzyme inhibition and antibacterial potential of 4-Hydroxycoumarin derivatives

The 4-Hydroxycoumarin derivatives are known to show a broad spectrum of pharmacological applications. In this paper we are reporting the synthesis of a new series of 4-Hydroxycoumarin derivatives synthesized through Knovenegal condensation; they were characterized by using UV-Vis, FT-IR, NMR spectroscopies. The synthesized compounds were evaluated for antibacterial activity against Staphylococcus aureus and Salmonella typhimurium strains. The compounds (2), (3) and (8) showed favorable antibacterial activity with zone of inhibitions 26.5± 0.84, 26.0 ± 0.56 and 26.0 ± 0.26 against Staphylococcus aureus (Gram-positive) respectively. However, the compounds (5) and (9) were found more active with 19.5 ± 0.59 and 19.5 ± 0.32 zone of inhibitions against Salmonella typhimurium (Gram-negative). Whereas, in urease inhibition assay, none of the synthesized derivatives showed significant anti-urease activity; although, in carbonic anhydrase-II inhibition assay, the compound (2) and (6) showed enzyme inhibition activity with IC50 values 263±0.3 and 456±0.1, respectively.

Effects of Gamma Interferon on Intestinal Epithelial Cells Stimulated with Salmonella Enterica serovar Typhimurium and Candida albicans.

Aims: The objective of this study was to determine the level of secretion of gammainterferon by interferon-primed and unprimed Caco-2 intestinal epithelial cells and their survival or growth following infection with Salmonella enterica subsp. enterica serovar Typhimurium (ATCC 14028), Salmonella enterica subsp. enterica serovar Typhimurium DT104 (ATCC 700408), and Candida albicans (Robin) Berkhout, anamorph (ATCC 10231) as well as the survival of the test microorganisms following infection. Study Design: Controlled laboratory experiments were performed using two different species of Salmonella and adenocarcinoma Caco-2 cells. Untreated/ unprimed Caco-2 cells served as control; Caco-2 cells’ growth and interferon production were then determined using, Enzyme Linked Immunosorbent Assay (ELISA) and flow cytometry. Place and Duration of Study: Department of Biological & Environmental Sciences Alabama A& M University and Center for Excellence in Post-Harvest Technologies, North Carolina A&T University USA April 2008 and February 2010. Methodology: Cell culture supernatants of Caco-2 intestinal epithelial cells, primed and unprimed with IFN-γ were infected with either wild-type Salmonella Typhimurium 14028, Candida albicans10231 or multi-drug resistant Salmonella Typhimurium DT104 were collected and analyzed. ELISA and flow cytometry were used to determine apoptosis, cell growth and interferon production. The Bioscreen-C Automated Growth Curve Analysis System was used under controlled environment to determine the growth of the microorganisms in the presence of different concentrations of IFN-γ. Results: Secretion of IFN-γ from Caco-2 cells that were previously treated with 50μg/ml, 20μg/ml, 10μg/ml, 5μg/ml, and 2.5 μg/ml of IFN-γ were not concentration dependent. However, the amount of IFN-γ released from Caco-2 cells was dependent on microbial stimulus type. Cells that were pretreated with 5 μg/ml and 2.5 μg/ml of IFN-γ and then infected with Salmonella Typhimurium DT104 showed an increase in the amount of IFN-γ in the culture medium after 5 minutes. IFN-y induced CaCo-2 cell death was dose-dependent for S.Typhimurium DT104 and Candida albicans. Results are reported as mean ± SEM fortriplicate values from three independent experiments at each time point and IFN-γ dose. Conclusion: These findings indicate that IFN-γ may serve as alternative antimicrobial compounds to reduce the persistence of multi-drug resistant microorganisms such as S. Typhimurium DT104. Induction of interferon-gamma production may be related to microbial virulence/pathogenicity. The potential of IFN-γ as a natural therapeutic for persistent infections in the immune-compromised populations still needs to be further investigated.

Prevalence of R-type ACSSuT in strains of Salmonella serovar Typhimurium DT193 isolated from human infections in Brazil / Prevalencia de resistencia de tipo ACSSuT en cepas de Salmonella serovariedad Typhimurium DT193 aisladas a partir de infecciones humanas en el Brasil

OBJECTIVE: To determine the prevalence of resistance to ampicillin, chloramphenicol, streptomycin, sulphonamides, and tetracyclines (ACSSuT) in Salmonella serovar Typhimurium definitive [phage] type (DT) 193 strains isolated from human sources over the last four decades. METHODS: From 2008 to 2010, 553 DT193 isolates out of 810 human-origin Salmonella ser. Typhimurium phage-typed strains isolated from the 1970s through 2008 were selected and tested for ACSSuT resistance: 91 strains isolated during the 1970s, 65 from the 1980s, 70 from the 1990s, and 327 from 2000-2008. Resistance profiles were determined using the disk diffusion method. RESULTS: †An antimicrobial susceptibility assay indicated 20.9 percent, or 116, of all isolates tested were ACSSuT-resistant, 52.0 percent (287) were resistant to one or more drugs in the ACSSuT profile, and 27.1 percent (150) were nonresistant (susceptible to antimicrobials). Based on the assay, overall antimicrobial resistance was extremely high in the 1970s (affecting 99.0 percent of isolates from that period) and remained high during the 1980s, when 95.4 percent of isolates had some type of antimicrobial resistance and incidence of Salmonella ser. Typhimurium DT193 R-type ACSSuT increased to 73.8 percent. R-type ACSSuT dropped to 27.1 percent (19 isolates) during the 1990s, and to 5.2 percent (17) during 2000-2008, despite a substantial increase in the number of isolates tested (397 versus 204, 111, and 98, respectively, for the previous three decades). CONCLUSIONS: †Although prevalence of Salmonella ser. Typhimurium DT193 R-type ACSSuT in Brazil has decreased since the 1970s, ACSSuT resistance markers continue to circulate. Therefore, continuous surveillance should be conducted to evaluate the occurrence of Salmonella ser. Typhimurium DT193 and its antimicrobial resistance.

OBJETIVO: Determinar la prevalencia de resistencia a la ampicilina, el cloranfenicol, la estreptomicina, las sulfonamidas y las tetraciclinas (ACSSuT) en cepas de Salmonella serovariedad Typhimurium fagotipo definitivo (DT) 193 aisladas de fuentes de origen humano durante las cuatro últimas décadas. MÉTODOS: Entre el 2008 y el 2010 se seleccionaron 553 aislados de DT193 entre 810 cepas de Salmonella serovariedad Typhimurium fagotipificadas aisladas desde la década de 1970 hasta el 2008, y en ellos se analizó la resistencia a ACSSuT: se estudiaron 91 cepas aisladas durante la década de 1970, 65 aisladas durante la década de 1980, 70 aisladas durante la década de 1990, y 327 aisladas entre el 2000 y el 2008, respectivamente. Los perfiles de resistencia a los antibióticos se determinaron mediante el método de difusión en disco. RESULTADOS: El antibiograma indicó que 20,9 por ciento (116) de todos los aislados que se analizaron fueron resistentes a ACSSuT, 52,0 por ciento (287) fueron resistentes a uno o más antibióticos del grupo ACSSuT y 27,1 por ciento (150) no fueron resistentes (es decir, fueron sensibles a dichos antibióticos). Según el análisis, la resistencia general a los antibióticos fue muy alta en la década de 1970 (y comprendió a 99,0 por ciento de los aislados de ese período) y continuó siendo alta durante la década de 1980, cuando 95,4 por ciento de los aislados presentó algún tipo de resistencia a los antibióticos y la incidencia de Salmonella serovariedad Typhimurium DT193 con resistencia de tipo ACSSuT aumentó hasta 73,8 por ciento. La resistencia de tipo ACSSuT descendió a 27,1 por ciento (31 aislados) durante la década de 1990, y a 5,2 por ciento (17 aislados) entre el 2000 y el 2008, a pesar del aumento importante en el número de aislados que se evaluaron (397 frente a 204, 111 y 98 en las tres décadas anteriores, respectivamente). CONCLUSIONES: Aunque la prevalencia de Salmonella serovariedad Typhimurium DT193 con resistencia de tipo ACSSuT en el Brasil ha disminuido desde la década de 1970, los marcadores de resistencia a ACSSuT continúan en circulación. Por consiguiente, debe llevarse a cabo una vigilancia permanente para evaluar la aparición de infecciones por Salmonella serovariedad Typhimurium DT193 y su resistencia a los antibióticos.

Tracing lineage by phenotypic and genotypic markers in Salmonella enterica subsp. enterica serovar 1,4,[5],12:i: - and Salmonella Typhimurium isolated in state of São Paulo, Brazil

Fifty-three Salmonella 1,4,[5],12:i:- and 45 Salmonella Typhimurium strains were characterised using phage typing, plasmid profiles and pulsed-field gel electrophoresis (PFGE) for comparison. The majority of the strains were subdivided into definitive type (DT) 41 (22.6 percent) and DT 193 (18 percent) and the 60-MDa plasmid was detected in 94.3 percent and 84.4 percent of strains, respectively. Genetic diversity was observed among all strains and 90 percent presented a > 70 percent similarity through PFGE analysis. These results suggest a close relationship between Salmonella 1,4,[5],12:i:- and Salmonella Typhimurium at the serotype level.

Antimicrobial susceptibility, phage types, and pulsetypes of Salmonella Typhimurium, in São Paulo, Brazil

A total of 283 Salmonella Typhimurium strains isolated from cases of human infections and non human sources, were examined for antimicrobial susceptibilityand the incidence of resistance was 38 percent and multiple resistance (to three or more antimicrobials) was 15 percent. All 43 multidrug-resistant strains (MDR) and 13 susceptible ones were characterized by phage typing and pulsed- field gel electrophoresis (PFGE). The strains encompassed 14 definitive phage types (DT), three were untypable (UT), and 18 atypicals or reaction does not conform (RDNC), which belonged to 21 PFGE patterns, A1-A21. The predominant phage types were DT49, DT193, and RDNC and two strains belonging to DT 104 and 104b were also identified. The most commum PFGE patterns were A1 and A8. Analysis by PFGE and phage typing demonstrated that the most of the MDR were multiclonal and association among multiresistance, phage typing, and PFGE patterns was not so significant.

Multidrug-resistant Salmonella typhimurium and Salmonella enteritidis identified by multiplex PCR from animals

Antibiotic resistance in Salmonella enteritidis and S. typhimurium, one of most frequent etiologic pathogens of food-borne bacterial gastroenteritidis in humans, is a serious health problem worldwide. Fifteen and 22 each of S. enteritidis and S. typhimurium were isolated from animals from 1983 to 1999 in Korea and tested for their antibiotic resistance patterns and phage types. S. enteritides isolates were highly resistant to sulfonamides (86.7%) and four of them (26.6%) showed multiple antibiotic resistance. The most frequent phage type (PT) of S. enteritids was PT1 (33.3%) even though none of them had multiple antibiotic resistance. S. typhimurium isolates were highly resistant to streptomycin, sulfonamides, and tetracycline, 100%, 95.5%, and 86.4% respectively. The incidence of multiple antibiotic resistance of S. typhimurium isolates was extremely high (100%) comparing to S. enteritidis isolates (26.7%). Two of the five ACSSuT type S. typhimurium isolates, resistant to ampicillin, chloramphenicol, streptomycin, sulfonamides, and tetracycline, were phage type DT104. All S. typhimurium isolates were sensitive to florfenicol. For the rapid detection of multiple antibiotic resistant S. enteritidis and S. typhimurium isolates, particularly ACSSuT type S. typhimurium DT104, antibiotic resistance genes, cmlA/tetR, PSE-1, and TEM, and Salmonella spp. Specific gene, SipB/C, were amplified using four pairs of primers in hot-started multiplex polymerase chain reaction. Two Korean isolates of S. typhimurium DT104 showed TEM amplicons instead of PSE-1 for the ampicillin resistance. The multiplex PCR used in this study was useful in rapid detection of ACSSuT type S. typhimurium and identification of b-lactamase gene distribution among Salmonella isolates.

Plasmid profiles, adhesive & invasive properties of Salmonella ser. Typhimurium strains: phage types 99 & 36.

Adhesive and invasive properties were compared with plasmid profile in S. Typhimurium strains of phage type 99(10) and 36(10). All strains of phage type 99 were multiple drug resistant (ApCmKmSmSuTcTp) and harboured small plasmids of 2.4-5.2 MDal. Six strains of the phage type 36 had ApCmTc R-pattern and two with only ampicillin resistance, carried plasmids of molecular size 2.6-5.2 MDal; two strains were sensitive to all antibiotics and devoid of plasmids. None of the strains were found to harbour high molecular weight plasmids. All plasmid positive strains of phage types 99 and 36 could be divided into two groups of three plasmid patterns each, which were phage type specific. All plasmid positive and negative strains adhered and invaded HeLa cells to different degrees. No correlation could be established between plasmid profile and adhesion invasion characteristics. High molecular weight plasmids therefore are unlikely to be essential for adhesion and invasion.

Plasmid profile analysis of Salmonella ser. Typhimurium phage untypable strains encountered in diverse geographic regions of India.

Plasmid profile analysis and antibiotic resistance pattern determination were carried out for 117 phage untypable S. Typhimurium strains. Majority of the strains (82%) were resistant to all the seven antibiotics tested, R-pattern being ApCmKmSmSuTcTp, rest (12%) showed heterogenous R-patterns. Plasmid DNA analysis revealed phage untypable strains to harbour large (58.8-114.3 MDal), intermediate size (36 MDal, 42 MDal) and small (1.8-5.2 MDal) plasmids with varying molecular weights. All the phage untypable strains could be subgrouped by plasmid profile analysis into 23 plasmid patterns. Plasmid profile analysis could discriminate large number of phage untypable strains on the basis of their plasmid pattern.

Obtención, aislamiento y caracterización de mutantes auxotróficos de salmonella typhinurium / Obtain, isolation and auxotrophics mutants of salmonella typhimurium

Se comprobó el efecto inductor mutagénico de la luz uv, obteniendo mutantes auxotróficos y morfológicos de salmonella typhimurium. El aislamiento de mutantes auxotróficos mediante la técnica de réplica en placa mejora con el uso de penicilina mediante el método de Hollyday, para la identificación de los requerimientos específicos de cada mutante, se caracterizó 3 mutantes auxotróficos de 24 mutantes escogidos al azar. De 24 mutantes auxotróficos, el 30 por ciento resultó ser metronina dependientes, y 25 por ciento revirtieron la características de mutantes auxotróficos.

Salmonella typhimurium isolated from bacteraemia.

During a two year period, a total of 15 strains of S. typhimurium were isolated and analysed by phage typing. Of these, 13 were found untypable, while two strains belonged to phage 76 and 22. All the strains were sensitive to Gentamicin and Cephaloridine. All but one showed multiple drug resistance.

Multiple drug resistant untypable Salmonella typhimurium infection in children & neonates.

Salmonella typhimurium infection in children and neonates is reported. Out of 21 cases, 6 were new-born and 13 were below one year of age. Clinical manifestations included fever, abdominal pain and diarrhoea. All the isolates were from stool, out of the total 21 cases, 4 expired. This study was done at Microbiology Department of Kasturba Medical College over a period of seven months.