The role of particle size on bio-fouling properties of oil-impregnated nano-porous silica coatings

The growth of algae, barnacles, moulds and other organisms on ship hulls, concretes, painted or coated surfaces, especially in the tropics, could be harmful and aesthetically unattractive. Control of such growths usually includes the use of coatings that may contain chemicals that can destroy these organisms, and in some cases, other lives. However, manipulation of the topography of material surfaces in the so called Slippery Liquid Infused Porous Surfaces (SLIPS) seems to be excellent safety approach of tackling bio-fouling problems. In this work, we have fabricated hydrophobic silica coatings of different particle sizes, ranging from 10 nm to 700 nm; the coatings have been impregnated with non-volatile oil (squalane) to obtain artificial rims of Nepenthes Pitcher plant. Wettability and anti-biofouling tests carried out on the fabricated coatings using water drops and algal cell media have shown that surfaces coated with the smallest nano-sized particles (10 nm) possess better stability and anti-biofouling characteristics toward algae adhesion.Keywords: Nano-particles, Porous coating, oil-impregnation, bio-fouling, wettabilit

High prevalence of toxic shock syndrome toxin–producing epidemic methicillin-resistant Staphylococcus aureus 15 (EMRSA-15) strains in Kuwait hospitals

This study characterized EMRSA-15 isolates obtained from patients in Kuwait hospitals for their genotypic relatedness, antibiotic resistance and carriage of virulence genes using pulsed-field gel electrophoresis (PFGE), coagulase serotyping, SCCmec subtyping, spa typing, multilocus sequence typing and DNA microarray. The isolates were resistant to trimethoprim (75.6%), ciprofloxacin (29.7%), erythromycin and clindamycin (24.3%), tetracycline (19.0%), and gentamicin and kanamycin (21.6%). All 37 isolates belonged to sequence type (ST) 22, coagulase type XI, three PFGE types and eight subtypes, ten spa types including t223 (51.3%), t852 (13.5%), t032 (8.1%), t790 (8.1%), t3107 (5.4%) and one each of t309, t2251, t3935, t5708 and t5983. Twenty-six isolates (70.2%) carried SCCmec IVa, eight isolates carried SCCmec IV and three isolates carried SCCmec IVh. All isolates carried agr1, cap5 and egc gene cluster (seg, sei, selm, seln, selo, and selu). tst (toxic shock syndrome toxin) was detected in 23 isolates. Eight isolates (21.6%) were positive for Panton-Valentine leukocidin (PVL). Genotypic analysis revealed that 62.1% of the isolates comprising ST22-IVa-t223 (51.3%) and ST22-IVa-t309/t2251/t3935/t5708 (10.8%) were CC22-[tst1+] UK EMRSA-15/Middle Eastern variant, 21.6% were CC22-PVL+ EMRSA-15 variant and 16.2% were CC22-UK EMRSA-15/Barnim clone. These results show that the tst1 positive-ST22-IVa-t223 (Middle Eastern variant) and the CC22-PVL+ EMRSA-15 variant were the dominant EMRSA-15 variants in Kuwait hospitals

DNA microarray analysis of 'Staphylococcus aureus' from Nigeria and South Africa

'Staphylococcus aureus' is an important human pathogen with an arsenal of virulence factors and a propensity to acquire antibiotic resistance genes. The understanding of the global epidemiology of 'S. aureus' through the use of various typing methods is important in the detection and tracking of novel and epidemic clones in countries and regions. However, detailed information on antibiotic resistance and virulence genes of 'S. aureus', and its population structure is still limited in Africa. In this study, 'S. aureus' isolates collected in South Africa (n = 38) and Nigeria (n = 2) from 2001–2004 were characterized by spa typing and DNA microarray. The combination of these two methods classified the isolates into seven spa types and three clonal complexes (CCs) i.e. t064-CC8 (n = 17), t037-CC8 (n = 8), t1257-CC8 (n = 6), t045-CC5 (n = 5), t951-CC8 (n = 1), t2723-CC88 (n = 1), t6238-CC8 (n = 1), and untypeable-CC8 (n = 1). A high percentage agreement (>95%) and kappa coefficient (>0.60) was largely observed with antibiotic susceptibility testing and DNA microarray, indicating substantial agreement. Some antibiotic and virulence gene markers were associated with specific clones. The detection of the collagen-binding adhesion ('cna') gene was unique for t037-CC8-MRSA while the enterotoxin gene cluster ('egc') and staphylococcal complement inhibitor ('scn') gene were identified with t045-CC5-MRSA. Moreover, the combination of genes encoding enterotoxins ('entA', 'entB', 'entK', 'entQ') was noted with most of the CC8 isolates. The t045-CC5-MRSA clone was positive for the mercury resistance ('mer') operon. DNA microarray provides information on antibiotic resistance and virulence gene determinants and can be a useful tool to identify gene markers for specific 'S. aureus' clones in Africa

Genotyping of methicillin-resistant Staphylococcus aureus in the Sultan Qaboos University Hospital, Oman reveals the dominance of Panton–Valentine leucocidin-negative ST6-IV/t304 clone

The objective of this study was to determine the prevalence and distribution of methicillin-resistant Staphylococcus aureus (MRSA) genotypes circulating at a tertiary hospital in the Sultanate of Oman. A total of 79 MRSA isolates were obtained from different clinical samples and investigated using antibiogram, pulsed-field gel electrophoresis (PFGE), staphylococcal chromosome cassette mec (SCCmec), Spa typing and multilocus sequence typing (MLST). The isolates were susceptible to linezolid, vancomycin, teicoplanin, tigecycline and mupirocin but were resistant to tetracycline (30.4%), erythromycin (26.6%), clindamycin (24.1%), trimethoprim (19.0%), ciprofloxacin (17.7%), fusidic acid (15.2%) and gentamicin (12.7%). Molecular typing revealed 19 PFGE patterns, 26 Spa types and 21 sequence types. SCCmec-IV (86.0%) was the dominant SCCmec type, followed by SCCmec-V (10.1%). SCCmec-III (2.5%) and SCCmec-II (1.3%) were less common. ST6-IV/t304 (n = 30) and ST1295-IV/t690 (n = 12) were the dominant genotypes followed by ST772-V/t657 (n = 5), ST30-IV/t019/t021 (n = 5), ST22-IV/t852 (n = 4), ST80-IV/t044 (n = 3) and 18 single genotypes that were isolated sporadically. On the basis of SCCmec typing and MLST, 91.2% of the isolates were classified as community-associated MRSA and 8.8% of the isolates (consisting of four ST22-IV/t852, one ST239-III/t632, one ST5-III/t311 and one ST5-II/t003) were classified as healthcare-associated MRSA. The study has revealed the dominance of a Panton–Valentine leucocidin-negative ST6-IV/t304 clone and provided insights into the distribution of antibiotic resistance in MRSA at the tertiary hospital in Oman. It also highlights the importance of surveillance in detecting the emergence of new MRSA clones in a healthcare facility