Evaluation of Staf-Sistem 18-R for identification of staphylococcal clinical isolates to the species level

Evaluation of Anti-Candida albicans Activities of Herbal Preparations Sold at the Kumasi Central Market in the Ashanti Region of Ghana

Candida albicans (C. albicans) is predominantly the leading cause of candidiasis among women with urogenital candidiasis. Since most people in resource-limited countries depend on herbal medicine for their primary care needs, many herbal drugs are sold to manage various infectious diseases. This study, therefore, evaluated the anti-C. albicans activities of five selected herbal preparations indicated for treating candidiasis sold at the Kumasi Central Market in the Ashanti Region of Ghana. The market was divided into five clusters, and one herbal preparation was randomly selected from each cluster. Using the Kirby Bauer disc diffusion antimicrobial susceptibility test, the herbal preparations were tested against clinically isolated C. albicans. Fluconazole, a standard antifungal drug, was included in the evaluation as a positive control. The experiments were performed on three different days and each in triplicates. Among the five selected herbal preparations, only one was effective against C. albicans with a mean inhibition zone of 19.1 mm. This effective herbal drug was prepared from Centella asiatica sap, Turnera microphylla leaves, and Vitex agnus-castus leaves. The results suggest that not all the herbal preparations selected were effective against C. albicans. Hence, we recommend that the authorities continually check the effectiveness of the herbal preparations on the market.

Comparison of methods for the identification of coagulase-negative staphylococci

Coagulase-negative staphylococci (CNS) species identification is still difficult for most clinical laboratories. The scheme proposed by Kloos and Schleifer and modified by Bannerman is the reference method used for the identification of staphylococcal species and subspecies; however, this method is relatively laborious for routine use since it requires the utilization of a large number of biochemical tests. The objective of the present study was to compare four methods, i.e., the reference method, the API Staph system (bioMérieux) and two methods modified from the reference method in our laboratory (simplified method and disk method), in the identification of 100 CNS strains. Compared to the reference method, the simplified method and disk method correctly identified 100 and 99% of the CNS species, respectively, while this rate was 84% for the API Staph system. Inaccurate identification by the API Staph method was observed for Staphylococcus epidermidis (2.2%), S. hominis (25%), S. haemolyticus (37.5%), and S. warneri (47.1%). The simplified method using the simple identification scheme proposed in the present study was found to be efficient for all strains tested, with 100% sensitivity and specificity and proved to be available alternative for the identification of staphylococci, offering, higher reliability and lower cost than the currently available commercial systems. This method would be very useful in clinical microbiology laboratory, especially in places with limited resources.

Identification and antimicrobial susceptibility patterns of Staphylococcus spp. isolated from canine chronic otitis externa

Swab samples obtained from 96 dogs with chronic otitis externa were cultured for the isolation of Staphylococcus species. Of 57 staphylococcal strains, 41 (72%) were coagulase-negative (CNS). The identification of staphylococci strains was made by standard procedures for the routine identification of staphylococci in clinical practice. S. sciuri was the most frequent species isolated (22.8%) from chronic otitis externa in dogs followed by S. intermedius (12.3%), S. auricularis (10.5%) and S. aureus (8.8%). Three (5.2%) CNS strains could not be identified. Bacterial isolates were susceptible to enrofloxacin, gentamicin, cephalothin, chloramphenicol and neomycin. Resistance was most common to penicillin G, oxacillin and ampicillin.

Glyceraldehyde-3-phosphate dehydrogenase-encoding gene as a useful taxonomic tool for Staphylococcus spp

The gap gene of Staphylococcus aureus, encoding glyceraldehyde-3-phosphate dehydrogenase, was used as a target to amplify a 933-bp DNA fragment by PCR with a pair of primers 26 and 25 nucleotides in length. PCR products, detected by agarose gel electrophoresis, were also amplified from 12 Staphylococcus spp. analyzed previously. Hybridization with an internal 279-bp DNA fragment probe was positive in all PCR-positive samples. No PCR products were amplified when other gram-positive and gram-negative bacterial genera were analyzed using the same pair of primers. AluI digestion of PCR-generated products gave 12 different restriction fragment length polymorphism (RFLP) patterns, one for each species analyzed. However, we could detect two intraspecies RFLP patterns in Staphylococcus epidermidis, Staphylococcus hominis, and Staphylococcus simulans which were different from the other species. An identical RFLP pattern was observed for 112 S. aureus isolates from humans, cows, and sheep. The sensitivity of the PCR assays was very high, with a detection limit for S. aureus cells of 20 CFU when cells were suspended in saline. PCR amplification of the gap gene has the potential for rapid identification of at least 12 species belonging to the genus Staphylococcus, as it is highly specific.

Rapid and accurate identification of Staphylococcus species by tRNA intergenic spacer length polymorphism analysis

PCR-amplified tRNA gene (tDNA) intergenic spacer length polymorphism (tDNA-ILP) was analyzed for its ability to identify to the species level type strains (n = 18) and clinical isolates (n = 163) of staphylococci. Amplified products obtained by PCR with outwardly directed consensus tDNA primers were separated by agarose and polyacrylamide gel electrophoreses. The results were compared with those obtained by biochemical identification and ribotyping. Each type strain presented a specific tDNA-ILP pattern. PCR with fluorescent primers allowed for the detection of labelled DNA fragments on polyacrylamide gels by using an automated laser fluorescence sequencer and provided enhanced pattern resolution in comparison with that by analysis on agarose gels. tDNA patterns indistinguishable from those of the type strains were produced by clinical isolates of all tested species except for some isolates of S. aureus (n = 3) and S. haemolyticus (n = 1), which showed variant patterns. Strains of S. saprophyticus and S. xylosus showed very closely related profiles, and S. cohnii subspecies were indistinguishable. The identities obtained by tDNA-ILP analysis agreed with those obtained by the biochemical method to the species level for 99% (162 of 163) of the strains tested and to the subspecies level for 96% (156 of 163) of the strains tested. These results indicate that fluorescence-labelled PCR analysis of tDNA-ILP provides an accurate and rapid molecular method for the identification of human staphylococci.