Mutagenic and Genotoxic Screening of Eight Commonly used Skin Whitening Creams in Nigeria

Skin whitening (bleaching) creams are often used to deliberately lighten the skin in response to social pressures or for the treatment of skin pigmentation. Bleaching creams contain varied concentrations of hydroquinone, corticosteroids, ammoniated mercury and kojic acid. Prolonged use of these creams may have deleterious (mutagenic) effect on the genetic material (DNA) of body cells. The purpose of this study was to evaluate the mutagenicity potentials of eight commonly used bleaching creams (Body white, Tura, Maxitone, Movate, Amos white, Top gel, Ultra clair, Fair and white), using the modified Ames test (with and without metabolic activation) that uses the wild type Escherichia coli (0157:H7) as tester strain. The assay was examined for revertant strains of the organism with at least three alterations in the phenotypic characteristics of the wild type organism. Results obtained showed that the eight bleaching creams produced revertant strains of the organism with alteration in more than three of its phenotypic characteristics and compared favourably with the standard mutagen (ethidium bromide), which produced the same effect. Three mutation mechanisms (forward, backward and silent mutations) were identified. The introduction of liver enzymes (S9 mix) made no significant difference in the number of characteristics altered (p>0.05). The results of this study revealed that the eight bleaching creams were mutagenic in bacteria and could be said to possess carcinogenic potentials. Their mechanism of mutagenesis could also be by intercalation just as ethidium bromide

Transfer of tetracycline resistance gene (tetr) between replicons in some enteric bacteria of diarrhoeal origin from some hospitals in South-South, Nigeria

From April to June 2005, a total of 120 feacal samples were obtained from diarrheagenic patients (0-5 years) attending Baptist Medical Center, Eku (BMC), Central Hospital, Agbor (CHA) and University ofBenin Teaching Hospital, Benin City (UBTH). These were screened for the presence of bacteria that could cause diarrhoea. The enteric organisms isolated included Escherichia coli, Klebsiella spp.,Salmonella spp., Aeromonas spp., Shigella spp. and Shigella spp. Antimicrobial susceptibility testing among the isolates showed resistance to amoxicillin (92%), amoxicillin-clavulanic acid (84.4%),tetracycline (71.4%), gentamycin (43.5%), nalidixic acid (38.3%) and nitrofurantoin (7.9%). E. coli showed the highest resistance to most of the antibiotics. Tetracycline resistance gene was detected in about72% (110) of the total isolates, out of which 76 (69%) were subjected to curing experiment in the presence of 75 ìg/ml acridine orange. Sixty (79%) of tetracycline resistant isolates lost their tetracyclineresistance markers (tetr) indicating that the tetr gene was located on a plasmid. Attempt was made to transfer the tetr gene from one replicon to the other within the same species and from one genus to theother. The rate of intra-species transfer of tetr gene (67%) was significantly higher (< 0.05) than its rate of inter-generic transfer (24%)

Incidence and antibiotic susceptibility pattern of Staphylococcus aureus amongst patients with urinary tract infection (UTI) in UBTH Benin City, Nigeria

Staphylococcus aureus is one of the most widely spread human pathogen. Considering the havoc it causes on life and subsequently on the economy, it became necessary to determine its incidence andantibiogram in our environment for adequate control and treatment. Records of microbial cultures and antibiotic sensitivity test results of suspected cases of urinary tract infection (UTI) of the University ofBenin Teaching Hospital (UBTH) Benin City from January 1st to 31st December, 2005 were retrieved and statistically analyzed. Two thousand, one hundred and twelve (2,112) early morning mid-stream, urine samples were cultured and seven different microbial agents were isolated and identified. Staphylococuus aureus was found to be the most common organism isolated presenting 22.8%, closely followed by Klebsiella spp. (10.1%), Escherichia coli (8.2%), Proteus mirabilis (4.8%), Enteronacter spp. (4.4%), Pseudomonas aeruginosa (2.0%) and Candida albican (1.0%). No growth was recorded in 46.6%of cultures. The occurrence of S. aureus was found to be significantly higher (65.8%) in females compared to males (34.2%) (P>0.05). 35% of cases were observed between the ages of 21 to 30 yearsand the majority were female (46.7%). The S. aureus strains were sensitive to augmentin (83%), oxfloxacin (75.9%), nitrofurantion (63.5%) and gentamycine (50.2%). S. aureus was found to be highlyresistant to tetracycline (80.9%), naladixic acid (79.3%) and contrimoxazole (87.3%). It was observed that S. aureus, among other organisms isolated, is the leading cause of UTI in our environment. Augmentin and oxfloxacin could be the drug of choice in the treatment of S. aureus

Tyrosinase inhibitory activity of supernatant and semi-purified extracts from squid pen fermented with Burkholderia cepacia TKU025

[[abstract]]Reports of tyrosinase inhibitors from microorganisms are rare. The tyrosinase inhibitory activity was found from the culture supernatant of Burkholderia cepacia TKU025 with 1 % squid pen as the sole carbon/nitrogen source. The fourth-day supernatant showed the strongest tyrosinase inhibitory activity (500 U/ml) and the highest total phenolic content (789 μg/ml GAE). The supernatant was further purified by liquidâliquid partition, and it was found that the methanol extract exhibited the lowest IC50 value of 2 μg/ml in the tyrosinase inhibitory activity assay and was compared with the positive control kojic acid and vitamin C. Significant associations between the tyrosinase inhibitory potency and the total phenolic content were found for the supernatant, extract, and fractions. The tyrosinase inhibitory activity persisted even when it was treated with acidic or alkaline conditions of pH 2 or 12. The tyrosinase inhibitory activity remained at 100 %, even after treatment at 100 °C for 60 min. The tyrosinase inhibitor also showed antimicrobial activity against Escherichia coli, Bacillus cereus, Aspergillus fumigatus, and Fusarium oxysporum.[[booktype]]紙本[[booktype]]電子