Fluorescent in situ hybridization (FISH) allows rapid detection of microorganisms. We aimed (i) to evaluate the sensitivity and specificity of FISH for the detection of Acinetobacter spp. in blood culture specimens and (ii) to test the simultaneous application of two genus-specific probes labeled with the same fluorochrome to increase the fluorescent signal intensity and improve the detection of Acinetobacter spp. Three hundred and twenty blood culture specimens were tested via both the conventional laboratory methods and FISH to detect Acinetobacter spp. The specimens were examined separately with each genus-specific probe Aci and ACA, and also using a mixture of the both probes Aci and ACA. In all examinations, probe EUB338 was used accompanied by Aci and ACA. The specificity of FISH was 100% (97.5% confidence interval [CI] = 98.7% - 100%). The sensitivity of FISH by the use of probe Aci was 96.4% (95% CI = 81.7% - 99.9%), whereas, the sensitivity of this technique by the use of probe ACA as well as by the combination of both probes Aci and ACA was 100% (97.5% CI = 87.7% - 100%). Moreover, simultaneous hybridization by probes Aci and ACA increased the fluorescent signal of Acinetobacter spp. cells to 3+ in 13 specimens. In conclusion, FISH, particularly using a combination of Aci and ACA, is a highly accurate method for the detection of Acinetobacter spp. in blood cultures. Furthermore, simultaneous hybridization by the both probes Aci and ACA can increase the fluorescent signal intensity of Acinetobacter spp. cells in some blood culture specimens and facilitate the detection of these microorganisms.

Background and Aims: The most important factor for pathogenicity of Staphylococcus epidermidis is the ability to produce biofilm. Identification of biofilm-forming strains using an appropriate method and recognizing the mechanisms of biofilm formation can help understand the proper use of artificial medical equipment and prevent increased drugs resistance. The aim of this study was to 1) evaluate the biofilm formation of S. epidermidis isolates using phenotypic methods such as Tube Method (TM), Congo Red Agar Method (CRA) and Microtiter Plates Method (MTP) as well as PCR of the genes icaA and icaD 2) determine the drug resistance pattern of S. epidermidis isolates and its association with biofilm formation among clinical specimens and samples of healthy carriers. Materials and Methods: A total of 90 strains of S. epidermidis including 50 clinical isolates and 40 strains from healthy carriers were studied using the phenotypic methods TM, CRA and MTP, and the molecular PCR of the genes icaA and icaD. Antibiotic resistance profile of the strains was performed using disk diffusion method according to the CLSI standards. Results: A total of 90 strains (63.34% by TM, 37.78% by CRA method and 67.79% of MTP method) were able to form biofilm. No significant differences were found between the healthy and carriers groups in terms of antibiotic resistance. The icaA and icaD genes were detected among 100% and 85.24% of the biofilm forming strains, respectively. Conclusions: Comparing the phenotypic and molecular methods for the detection of biofilm formation among S. epidermidis isolatesshowed that MTP is the best method with the highest sensitivity and specificity and its simultaneous use with molecular methods is recommended.

Background: Stenotrophomonas maltophilia is a serious causative agent for bacteremia. Rapid identification of S. maltophilia in blood cultures is important to enable a satisfactory pathogen-based antibiotic therapy at an early stage. The aim of this study was to evaluate fluorescence in situ hybridization (FISH) for the identification of S. maltophilia in blood culture specimens.Methods: Three hundred positive blood culture specimens were examined by both FISH and conventional laboratory methods for the identification of S. maltophilia. The results of FISH were compared with the results of the conventional methods.Results: By conventional cultural and biochemical methods, S. maltophilia was identified in 47 blood culture specimens. Fluorescence in situ hybridization identified S. maltophilia in 46 of these 47 S. maltophilia-positive blood cultures. Thus, the sensitivity and specificity of FISH were 97.9% and 100%, respectively.Conclusions: Our findings suggest that FISH is a suitable method for the identification of S. maltophilia in blood cultures.

The production of pigments from bacteria is significant due to the low cost, high yield and ease of extract compared with other sources. Carotenoids are one of the most important pigments with antioxidant properties which are the precursor of vitamin A synthesis and have antibody overproduction ability, anti-tumor activity and inhibitory effect on the cardiovascular disease. The present study aimed to isolate and identify carotenoid-producing bacteria by highperformance liquid chromatography (HPLC) analysis of their carotenoid pigments. Twenty soil samples were collected from different regions of Tehran. After serial dilution each sample was cultured on BHI agar medium and incubated at 37°C. The pigment-producing bacteria were selected for further identification and their pigments were extracted by