Talat El-kersh - Academia.edu (original) (raw)

Papers by Talat El-kersh

Journal of pure and applied microbiology, Jun 2, 2024

ChemInform, 2007

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was e... more ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF.

PubMed, 2002

Objective: To detect group B streptococcal carrier state of Saudi females during 3rd trimester of... more Objective: To detect group B streptococcal carrier state of Saudi females during 3rd trimester of pregnancy and to assess type of specimens and the techniques used for the organism detection. Methods: A total of 867 consecutive vaginal and rectal swabs were obtained from 217 pregnant women at > 28 weeks of gestation and their follow up testing from King Khalid University Hospital, Riyadh, Kingdom of Saudi Arabia. Swab-specimens were cultured comparatively on Islam and Edwards blood agar plates, and into selective Lim broth. Enrichment Lim broth cultures (>12 hours) with and without positive modified coagglutination test were then subcultured on Islam and Edwards sheep blood agar plates. Presumptive colonies were then tested for group B streptococcus identity by convential biochemical reactions, serogrouping and serotyping. Collected neonatal swab-specimens (184) were also treated similarly. Results: In comparison to Lim broth enrichment culture, the direct swab specimen culture on Edwards blood agar or Islam agar plates technique revealed 84% sensitivity and 100% specificity, whereas modified coagglutination test after selective Lim broth enrichment revealed 100% sensitivity and 96% specificity. Group B streptococcus was isolated in at least one of the specimens from the 217 patients in 66 cases. Of these 66 cases, group B streptococcus was isolated from both vaginal and rectal swabs in 33 (50%) cases and only from vaginal swabs in 22 (33%) and rectal swabs in 11 (17%) cases. Of the group B streptococcus positive cases, 10 (15%) cases had spontaneously lost their carriage, upon follow up testing, whereas out of the 151 negative cases, 4 (2.6%) cases became positive for group B streptococcus colonization upon follow up testing with an overall carriage rate of (60/217) 27.6%. Certain demographic factors were found to alter such rate of carriage. Additionally, 50% of group B streptococcal colonized mothers vertically transmitted the homologous serotypes of the organism to their newborns, but clinical infection was not recorded during the study period. Conclusion: Group B streptococci colonization rate among term Saudi pregnant women is relatively high (27.6%); and thereby constitutes a group of women whose infants are at great risk of early-onset invasive disease. The modified coagglutination test after growth amplification seems rapid and cost-effective to detect lightly or heavily group B streptococcal colonized women. Vaginal and rectal swab specimens at late pregnancy appeared necessary to accurately identify group B streptococcus maternal colonization.

Annals of Saudi medicine

Commensal neonatal fecal flora constitute a reservoir of antibiotic resistance. The aim of this s... more Commensal neonatal fecal flora constitute a reservoir of antibiotic resistance. The aim of this study was to characterize the prevalence of fecal carriage of extended spectrum beta lactamases (ESBLs) and carbapenemase producing gram-negative bacteria among 150 neonates who were born in two hospitals in central Saudi Arabia. From June 2012 to January 2013, 150 healthy neonates.

Saudi medical journal, 2002

To detect group B streptococcal carrier state of Saudi females during 3rd trimester of pregnancy ... more To detect group B streptococcal carrier state of Saudi females during 3rd trimester of pregnancy and to assess type of specimens and the techniques used for the organism detection. A total of 867 consecutive vaginal and rectal swabs were obtained from 217 pregnant women at > 28 weeks of gestation and their follow up testing from King Khalid University Hospital, Riyadh, Kingdom of Saudi Arabia. Swab-specimens were cultured comparatively on Islam and Edwards blood agar plates, and into selective Lim broth. Enrichment Lim broth cultures (>12 hours) with and without positive modified coagglutination test were then subcultured on Islam and Edwards sheep blood agar plates. Presumptive colonies were then tested for group B streptococcus identity by convential biochemical reactions, serogrouping and serotyping. Collected neonatal swab-specimens (184) were also treated similarly. In comparison to Lim broth enrichment culture, the direct swab specimen culture on Edwards blood agar or Is...

Egyptian dental journal, 1987

British Microbiology Research Journal, 2014

Aims: To investigate the effect of human serum, starvation and /or variation in incubation temper... more 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.

Journal of Infectious Diseases, 1995

The effect of subinhibitory concentrations of ciprofloxacin, lomefloxacin, norfloxacin, ofloxacin... more The effect of subinhibitory concentrations of ciprofloxacin, lomefloxacin, norfloxacin, ofloxacin, and sparfloxacin on urease activity and on cell surface hydrophobicity of urea-splitting bacteria was examined. Quinolones at 0.5 MICs demonstrated variable effects on bacterial-urease activity. Norfloxacin inhibited enzyme activity in Proteus vulgaris and Proteus mirabilis, while other quinolones had no effects. In Morganella morganii, sparfloxacin and ciprofloxacin enhanced urease activity, particularly at the initial phase of growth. All quinolones tested showed no marked effect on urease activity by Providencia rettgeri. Quinolones at the same concentrations induced an increase in the cell surface hydrophobicity, which was strain-dependent. There was no correlation between urease inhibition and cell surface hydrophobicity. Inhibition of urease activity by quinolones, in addition to their antibacterial activities, may prevent the progression of urinary tissue damage and stone formation.

AFRICAN JOURNAL OF BIOTECHNOLOGY, 2011

A total of 500 soil samples were collected from different localities across the kingdom to isolat... more 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.

African Journal of Microbiology Research, 2012

Group B streptococcus (GBS) is a significant cause of serious infections in neonates and the comp... more Group B streptococcus (GBS) is a significant cause of serious infections in neonates and the composition of the vaginal micro-biota also affect neonatal outcome. To investigate vaginal carriage of Group B streptococcus in 217 term Saudi pregnant women, the direct antigen detection method in selective enrichment broth, Todd-Hewitt broth with 8 µg/ml gentamicin and 15 µg/ml nalidixic acid, using 2 commercial kits was used and compared to Centers for Disease Control and Prevention, CDCgold standard method where following enrichment conventional means for identifying GBS is through isolation on subculture to blood agar plates, which requires 72 h before a final result is achieved. Phenotypic traits of Group B streptococcus serotypes distribution, antibiotic susceptibility patterns, biofilm formation and its associated vaginal micro-biota were also studied. The CDC-gold standard method positivity rate of Group B streptococcus was 23%, with no significant correlation with any of the studied demographic factors. In comparison, direct antigen detection method in boiled selective enrichment broth growth revealed 52.2 and 100% sensitivity and 100% specificity after growth amplification for 4 and 18 h incubation, respectively. Of 50 Group B streptococcus isolates, serotype II was the most predominant (42%), followed by serotype IV (16%). No resistance to ampicillin, cefepime, ceftriaxone or vancomycin was found, but 10, and 6%, of the strains were resistant to erythromycin and clindamycin, respectively. Overall 54% of Group B streptococcus strains were biofilm producers, but (100%) among serotype Ib, III, or V. Of several coexistent, Escherichia coli and Enterococcus feacalis were the most frequently Group B streptococcus-associated organisms, but with no statistical correlation.

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

11 Samples of the Bacillus thuringiensis (Bt)

African Zoology, 2021

Mosquito resistance to insecticides has recently increased the burden of the majority of mosquito... more Mosquito resistance to insecticides has recently increased the burden of the majority of mosquito-borne diseases, and controlling the spread of these diseases should mainly rely on vector control measures. The present study aimed to investigate the toxicity of locally isolated mosquitocidal Bacillus thuringiensis (Bt) isolates and toxin complexes (TCs) from the two nematode bacterial symbionts Photorhabdus luminescens akhurstii (HRM1) and Photorhabdus luminescens akhurstii (HS1) on Aedes caspius. Out of sixty-eight local Bt isolates, four showed LC50 values ranging from 13.8–15.6 ppm, similar to LC50 recorded against the reference Bacillus thuringiensis israelensis (Bti-H14) (13.0 ppm). Seventeen isolates were more toxic than the Bti-H14 by 1.3–11.1 fold (LC50 values 1.17–9.9 ppm vs 13.0 ppm). Two isolates were less toxic than Bti-H14, showing LC50 values of 39.4 and 24.1 ppm, respectively. Additionally, the TCs from HRM1 and HS1 showed promising larvicidal toxicity, with HS1 being ...

Samples of the Bacillus thuringiensis (Bt) and Pseudomonas frederiksbergensis (Pf), both proved t... more Samples of the Bacillus thuringiensis (Bt) and Pseudomonas frederiksbergensis (Pf), both proved to be safe to living 12 organisms and environment, were isolated from rural soil of Saudi Arabia, and evaluated for entomopathogenicity 13 against 3 rd larval stage of Culex pipiens. Spore-crystal mixture of the Bt isolate showed a mosquitocidal activity 14 similar to that of the reference B. t. israelensis H14 (Bti-H14). However, toxin extract of Pf, identified as glycolipid 15 biosurfactants, showed 14 times higher toxicity than that of the Bti-H14. This significant difference in toxicity could 16 be attributed to the difference in the bacterial product used as it was the purified crude toxins of pf compared to 17 spore-crystal mixture of Bt isolate or Bti-H14. Light and electron microscopy showed destructive effects for the Pf 18 toxin extract on the midgut epithelial layer of treated larvae. Epithelial cells were first appeared with cytoplasmic 19 extensions followed by cellular and n...

This study investigated the prevalence and Antibiotic sensitivity profiles of Gram negative bacte... more This study investigated the prevalence and Antibiotic sensitivity profiles of Gram negative bacteria (GNB) isolated from urine specimens of out-patients with urinary tract infections (CA-UTI) in Armed Forces Hospital in southern Saudi Arabia, risk factors for infection, and extended spectrum β-lactamase production (ESBLs). The Vitek2 system (BioMe rieux, France), was used for microbial identification, susceptibility testing, and ESBL detection, which was also confirmed by the Clinical and Laboratory Standards Institute double-disk synergy test. A total of 269 GNB were studied. E. coli accounted for 77 % (206/269), Klebsiella pneumoniae for 16 % (43/269) and other GNB 7% (20/269). Fifty four % (23/43) of K. pneumoniae and 44% (91/206) of E coli isolates, were ESBL positive. Females comprised 74% (200/269) of patients, and 14% (37/269) were pregnant. Patients aged ≤10 years and those aged 7180 years showed significant high risk to CA-UTI at frequency of 20.4 % (55/269) and 24.9 %(67/2...

Molecules, 2019

Currently, global efforts are being intensified towards the discovery of local Bacillus thuringie... more Currently, global efforts are being intensified towards the discovery of local Bacillus thuringiensis (Bt) isolates with unique anticancer properties. Parasporins (PS) are a group of Bt non-insecticidal crystal proteins with potential and specific in vitro anticancer activity. However, despite the significant therapeutic potential of PS-producing Bt strains, our current knowledge on the effects of these proteins is limited. Hence, the main objective of this study was to screen Bt-derived parasporal toxins for cytotoxic activities against colon (HT-29) and cervical (HeLa) cancerous cell lines. Nine non-larvicidal and non-hemolytic Bt strains, native to Saudi Arabia, were employed for the isolation of their parasporal toxins. 16S rDNA sequencing revealed a 99.5% similarity with a reference Bt strain. While PCR screening results indicated the absence of selected Cry (Cry4A, Cry4B, Cry10 and Cry11), Cyt (Cyt1 and Cyt2) and PS (PS2, PS3 and PS4) genes, it concluded presence of the PS1 ge...

2016 International Congress of Entomology, 2016

Background: The incidence of mosquito-borne diseases and the resistance of mosquitoes to conventi... more Background: The incidence of mosquito-borne diseases and the resistance of mosquitoes to conventional pesticides have recently caused a panic to the authorities in the endemic countries. This study was conducted to identify native larvicidal biopesticides against Culex pipiens for utilization in the battle against mosquito-borne diseases. Methods: Larvicidal activities of new indigenous Bacillus thuringiensis isolates and crude toxin complexes (TCs) of two nematode bacterial-symbionts, Photorhabdus luminescens akhurstii (HRM1) and Ph. luminescens akhurstii (HS1) that tested against Cx. pipiens. B. thuringiensis isolates were recovered from different environmental samples in Saudi Arabia, and the entomopathogenic nematodes, Heterorhabditis indica (HRM1) and He. sp (HS1) were isolated from Egypt. Larvicidal activities (LC50 and LC95) of the potentially active B. thuringiensis strains or TCs were then evaluated at 24 and 48h post-treatment. Results: Three B. thuringiensis isolates were almost as active as the reference B. thuringiensis israelensis (Bti-H14), and seven isolates were 1.6-5.4 times more toxic than Bti-H14. On the other hand, the TCs of the bacterial symbionts, HRM1 and HS1, showed promising larvicidal activities. HS1 showed LC50 of 2.54 folds that of HRM1 at 24h post-treatment. Moreover, histopathological examinations of the HS1-treated larvae showed deformations in midgut epithelial cells at 24h post-treatment. Conclusion: Synergistic activity and molecular characterization of these potentially active biocontrol agents are currently being investigated. These results may lead to the identification of eco-friend mosquito larvicidal product(s) that could contribute to the battle against mosquito-borne diseases.

Saudi Medical Journal, 2016

Objectives: To investigate the prevalence, antibiotic resistant profiles, and risk factors of ear... more 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.