Talat A. El-Kersh

Risk factors of nasal carriage of Staphylococcus aureus and methicillin-resistant Staphylococcus aureus among health care staff in a teaching hospital in central Saudi Arabia

Objectives: To investigate possible risk factors of Staphylococcus aureus (S. aureus) and methicillin-resistant S. aureus (MRSA) nasal carriage associated with various health troubles among healthcare workers (HCWs) at King Khalid University Hospital (KKUH). Method: This prospective study was conducted between May 2012 and January 2013 in KKUH, Riyadh, Saudi Arabia. A total of 200 nasal swabs were collected from HCWs. Identification was carried out based on morphology, Gram stain, catalase and coagulase test, Staphaurex PlusH test, chromogenic medium, oxacillin, and cefoxitin test using disc diffusion method. Characterization was carried out using disk diffusion method and E-test. Polymerase chain reaction was carried out to confirm using GeneXpert® Dx System (Cepheid) to detect mecA gene. Results: Among the 200 isolates, 80 (40%) were S. aureus carriers, and 36 (18%) of all HCWs were identified as MRSA carriers. There was a significant difference of S. aureus according to gender with male carriers (p=0.012), occupation particularly among nurses (p=0.006), and duration of working years in the hospital among 4-6 years group (p=0.002). Moreover, none of the risk factors assessed were significantly associated with the carriage rate of MRSA (p>0.05). Conclusion: The current study revealed that nursing staff was the potential colonizers of S. aureus and MRSA compared with other HCWs. Regular screening of carriers is required for prevention of nosocomial infections.

Isolation and characterization of native Bacillus thuringiensis isolates from Saudi Arabia

A total of 500 soil samples were collected from different localities across the kingdom to isolate native Bacillus thuringiensis (Bt) strains. Sodium acetate- (0.25 M) -selection heat-pasteurization, and 50% ethanol treatment methods were used for Bt isolation. Phenotypic characterization and identification of recovered Bt isolates was accomplished on the basis of morphological characteristics of colonies, parasporal crystal, and spores, as well as hemolytic activity, motility, susceptibility to antibiotics, and carbohydrate utilization (API 50CH system). Analysis of 16S rRNA gene was performed to further confirm Bt species identity and differentiate the spore-forming bacilli. Bioassay tests were conducted on larvae of Aedes caspius and Culex pipiens . Based on results, a total of 64 Bt isolates were recovered and the overall Bt index corresponding to the whole sampling areas was 0.25. Most of Bt isolates showed spherical crystals (56%), while, irregular, bipyramidal, and attached crystal to the spores constituted 14, 10 and 6% respectively. The most common biochemical type (31%) was as that of the reference Bt subsp. kurstaki (Btk). The 16S rRNA gene analysis, using the universal primer, provided an efficient identification of Bt isolates and their discrimination from the closely related Bacillus cereus , as well as from other spore forming bacilli. Bioassay showed that only one Bt isolate exhibited anti-diptera activity similar to Btk strain while most of the native Bt isolates exhibited weak (<30% mortality) or non insecticidal activity. However, results of motility, hemolytic activity, antibiotic-susceptibility patterns, and crystal shape, seem to suggest that many of our Bt isolates may exhibit parasporins activity. Key words: Bacillus thuringiensis , parasporal crystal, isolation, biochemical type, insecticidal, cry gene, mosquitoes.

Prevalence and risk factors of early fecal carriage of Enterococcus faecalis and Staphylococcus spp and their antimicrobial resistant patterns among healthy neonates born in a hospital setting in central Saudi Arabia

Objectives: To investigate the prevalence, antibiotic resistant profiles, and risk factors of early fecal carriage of Enterococcus faecalis (E. faecalis) and staphylococci among 150 healthy Saudi neonates born in a hospital setting in central Saudi Arabia. Methods: This prospective study was conducted in Al-Bukayriyah General Hospital, Qassim, Saudi Arabia, between June 2012 and January 2013. The E. faecalis and Staphylococcus spp. isolates were identified manually, and Vitek2 system was used for identity confirmation at the species level and minimum inhibitory concentration-susceptibility testing. Results: Enterococcus faecalis (n=73) and Staphylococcus spp. (n=18) were recovered. Unlike staphylococci, E. faecalis colonization did not significantly vary from day one up to 7 days of life, regardless of the type of feeding, but it was relatively higher among vaginally versus cesarean delivery. Both Staphylococcus epidermidis (S. epidermidis) and Staphylococcus aureus carriage increase as the body weight increases, and this difference was significant (p=0.025) for S. epidermidis. High-level resistance in Gentamycin among E. faecalis isolates was 25% and 11% to Streptomycin. Thirty percent of S. epidermidis were resistant to oxacillin and exhibited multidrug-resistant (MDR) patterns of 5 resistant markers, which were also observed among 2/5 (40%) of Methicillin-resistant Staphylococcus aureus isolates. Conclusion: Enterococcus faecalis did not significantly vary in relation to type of delivery, age up to 7 days, and type of feeding. The neonatal fecal carriage of MDR isolates should be considered as a crucial reservoir to the further spread of antimicrobial resistance genes among hospitals, cross infections, and the community.

Heparin-benzyl alcohol enhancement of biofilms formation and antifungal susceptibility of vaginal Candida species isolated from pregnant and nonpregnant Saudi women.

Biofilm formation by Candida species is a major contribute to their pathogenic potential.The aim of this study was to determine in vitro effects of EDTA, cycloheximide, and heparin-benzyl alcohol preservative on C. albicans (126) and non-albicans (31)vaginal yeast isolates biofilm formations and their susceptibility against three antifungal Etest strips. Results of the crystal violet-assay, indicated that biofilms formation were most commonly observed [100%] for C. kefyr, C. utilis, C. famata, and Rhodotorula mucilaginosa, followed by C. glabrata [70%], C. tropicalis [50%], C. albicans [29%], Saccharomyces cerevisiae [0.0%]. EDTA (0.3mg/ml) significantly inhibited biofilm formation in both C. albicans and non-albicans isolates (P=0.0001) presumably due to chelation of necessary metal cations for the process-completion. In contrast, heparin (-benzyl alcohol preservative) stimulated biofilm formation in all tested isolates, but not at significant level (P=0.567). Conversely, cycloheximide significantly (P=0.0001) inhibited biofilm formation in all C. albicans strains(126) and its effect was even 3 fold more pronounced than EDTA inhibition, probably due to its attenuation of proteins (enzymes) and/or complex molecules necessary for biofilm formation. Results also showed that all nonalbicans yeasts isolates were susceptible to 5-flucytosine (MIC50, 0.016 µg/ml; MIC90, 0.064 µg/ml), but 14% of C. albicans isolates were resistant (MIC50, 0.064 µg/ml; MIC90 >32 µg/ml). The MIC50 value of amphotricin B for all C. albicans and non-albicans isolates was at a narrow range of 0.023 µg /ml, and the MIC90 values were 0.047 µg/ml and 0.064 µg/ml respectively, thereby confirming its efficacy as a first line empiric- treatment of Candida spp infections.

A review of virulence factors, pathogenesis, and antibiotic resistance in Staphylococcus aureus

ISSN Staphylococcus aureus is a common pathogen associated with serious community and hospital-acquired diseases and has long been considered as a major problem of public health. This potent Gram-positive bacterium is able to bypass all barriers of the host defense system as it possesses a wide spectrum of virulence factors. S. aureus is also one of the prominent pathogens in biofilm-related infections of indwelling medical devices, which are responsible for billions in healthcare cost each year in the United States. S. aureus expresses a large number of virulence factors that are implicated in their pathogenesis. Methicillin-resistant S. aureus infections have reached epidemic levels in many parts of the world. This review describes the virulence factors, pathogenesis, and antibiotic resistance in S. aureus. Copyright 2016 Wolters Kluwer Health, Inc. All rights reserved.

Effect of incubation temperature and human serum on yeast to hyphal morphogenesis in vaginal Candida albicans and its correlation to virulence markers.

Aims: To investigate the effect of human serum, starvation and /or variation in incubation temperature on yeast and pseudo-hyphae and/ or hyphal cell differentiation in vaginal Candida albicans strains and, its correlation to exoenzymes productivity. Study Design: A total of 31 C. albicans strains previously isolated from high vaginal swab specimens of pregnant Saudi women, as well as the C. albicans QC strain ATCC 10231 were recruited from Brain Heart Infusion-glycerol stock cultures(-80oC) & included in the study. Place and Duration of Study: Department of Clinical Laboratory Sciences, College of Applied Medical Sciences, King Saud University, Riyadh, Saudi Arabia, between September 2013 and December 2013. Methodology: Each of thirty one vaginal C. albicans strains and the QC strain (ATCC Original Research Article British Microbiology Research Journal, 4(7): 798-812, 2014 799 10231) was grown in Modified Sabouraud Broth (MSB) at 25oC and at 37oC with or without addition of 20 % human serum; and morphological growth was observed at 2 hours intervals by phase contrast microscopy. Selected C. albicans strains that showed ability and/or weak-ability of yeast-hyphal transition were also tested for their exo-hydrolytic enzymes of phospholipase, and proteinase as caseinase, & gelatinase, and coagulase, virulence markers. Results: Showed that at 25oC 28/31(90.3%) strains were non filamentous, 3/31(9.6%) strains were moderately filamentous, and 0.0% strong filamentous, in comparison, at 37oC those numbers were 19/31(61.3%), 10/31(32.3%), and 2/31 (6.4%) respectively, suggesting that mere increase in temperature from 25oC to 37oC remarkably increases yeast morphogenesis to filamentous forms. Such increase was significantly (P<0.001) more pronounced upon the addition of 20% serum at either incubation temperature of 25oC or 37oC as expected. Generally the presence of serum and/or incubation at high temperature (37oC), speeds off hyphal growth formation. Additionally, results also showed that 8/31 (25.8%) strains exhibited transition to hyphal forms only in presence of serum, whereas 7/31 (22.6%), apparently lost their capacity to switch to hyphal forms even in presence of serum and/or at temperature of 37oC incubation. In contrast three strains 3/31, (9.7%) expressed such ability of filamentous growth in presence or absence of serum at 37oC as well as 25oC. These strains also showed enhanced secretion of exoenzymes. Therefore, these strains would be the most virulent ones. Whereas those strains (7/31, 22.6%) that did not show filamentous growth at any of the examined growth conditions would be considered as less virulent strains. However, considering the limited number of strains tested in this study, these findings require further substantiation by large sample size and in vivo animal studies. Conclusion: Results obtained suggest that vaginal C. albicans strains are heterogenous in their potency to switch from yeast to hyphae. Strains which show morphogenesis in absence of serum and/or at low temperature (25oC) exhibit higher exoenzymes activity suggesting that these strains are more pathogenic.