Prevalence and antibiogram study of Staphylococcus aureus isolated from clinical and selected drinking water of Dutsin-Ma, Katsina state, Nigeria

Background

Multidrug resistant Staphylococcus aureus in clinical and environmental samples is a global problem. Data comparing antibiogram of bacteria from these two sources in Nigeria is scarce. Therefore, this study compares antibiogram of isolates from both sources from Dutsin-Ma, Katsina State, Nigeria.

Methodology

A total of 120 and 150 clinical and aquatic samples respectively were collected for a five months period. Samples were analyzed for isolation of S. aureus using mannitol salt agar. Bacteria identification were carried out using standard biochemical characterization. Antibiogram of the isolates were determined using disc diffusion methods and comparison with Clinical Laboratory Standard Institute (CLSI)'s Standard.

Result

A total of 120 and 45 S. aureus were isolated from both clinical and aquatic samples respectively. Highest (100.0%) resistance to cloxacillin was observed among isolates from each source. Clinical and aquatic isolates showed least resistance of 20.0% and 48.0% respectively to gentamicin. All isolated S. aureus (165) from this studies were multidrug resistant with different antibiotic resistant pattern.

Conclusion

This study revealed that multidrug resistance strains of S. aureus can be isolated from both clinical and drinking water sources, hence, a public health significance that calls for urgent attention by clinicians and public health workers.

Solubilization and characterization of diacylglycerol acyltransferase from microspore-derived cultures of oilseed rape

Particulate fractions prepared from microspore-derived (MD) embryos of oilseed rape (Brassica napus L. cv. Reston) and an embryogenic MD cell suspension culture of oilseed rape (B. napus L. cv. Jet Neuf) were used as a source of diacylglycerol acyltransferase (DGAT, EC 2.3.1.20) for enzyme characterization and development of a solubilization procedure. DGAT activity in the 1500-100,000 g fraction from MD embryos was stimulated 4-5-fold by 3 to 4 mg of BSA/ml of reaction mixture. DGAT activity from MD embryos was stimulated 2-3-fold by fluoride salts and 1.4-fold by NaCl, whereas iodide salts caused substantial inhibition of enzyme activity. The effect of the various 1:1 electrolytes on enzyme activity appeared to be related more to their differential effects on solution structure rather than ionic strength. DGAT was solubilized from membranes of MD embryos and the cell suspension culture by about 80 and 50% respectively, using 2 M NaCl in 1% (w/v) octanoyl-N-methyl-glucamide (MEGA-8) (pH 8.0 buffer) at a detergent to protein ratio of 2:1. The specific activity of solubilized DGAT was about 2-fold greater than that of the particulate enzyme. The mechanism of solubilization appeared to be related to the lowering of the critical micellar concentration of MEGA-8 in the presence of NaCl. DGAT, solubilized from MD embryos, eluted with an M(r) of about 2 x 10(6) during gel-filtration chromatography on a Superose 6 column equilibrated in buffer containing 0.1% (w/v) MEGA-8. The solubilized enzyme exhibited optimal activity at pH 7. At concentrations above 2 microM acyl-CoA, the specificity of solubilized DGAT for oleoyl-CoA and palmitoyl-CoA was considerably greater than for stearoyl-CoA.

Comparison of hexamethyldisilazane (HMDS), Peldri II, and critical-point drying methods for scanning electron microscopy of biological specimens

Three different drying methods, critical-point drying (CPD), Peldri II, and hexamethyldisilazane (HMDS), were compared using representative animal (rat kidney, trachea, duodenum, lung, and red blood cells) and plant (leaves from ten species of monocotyledons and dicotyledons) specimens. All three drying methods produced identical results with animal specimens. Plant specimens showed signs of shrinkage regardless of which drying method was employed. The order of preservation quality from best to worst for leaves was CPD > Peldri II > HMDS, with the CPD method providing substantially better results in all but one case. Postfixation of leaves with osmium tetroxide resulted in poorer preservation in all instances. Peldri II caused complete extraction of leaf cuticular wax, while both both CPD and HMDS showed minimal extraction compared with samples air dried directly from acetone. These results indicate that HMDS provides a time-saving and inexpensive alternative to CPD for animal specimens. Plant specimens, particularly those containing cells with large central vacuoles, are adequately preserved only with the CPD method. In addition, postfixation with osmium should be avoided when processing plant specimens for scanning electron microscopy.