A newly isolated Streptomyces sp. CS392 producing three antimicrobial compounds

With the aim of isolating new microbes capable of producing strong antimicrobial substances, strain CS392 was screened from 700 soil isolates preserved in our laboratory. The strain was related to genus Streptomyces based on various characteristics. Three highly active antimicrobial compounds, C1, C2 and C3, produced by the strain were purified by solvent extraction followed by silica gel column chromatography. These compounds were highly active against various Gram-positive resistant bacteria such as methicillin-resistant Staphylococcus aureus (MRSA), vancomycin-resistant Staphylococcus aureus (VRSA), and vancomycin-resistant Enterococcus (VRE). Among three, C3 was the most active against MRSA and VRSA with minimal inhibitory concentration (MIC) of 2 μg/ml while C2 and C3 had MIC values of 4 μg/ml for the strains. In case of Bacillus subtilis ATCC6633, C1 and C3 were more effective with MIC values of 0.5 μg/ml than C2 with MIC of 2 μg/ml. Those antibiotics were variably active (MIC of 4-32 μg/ml) against Micrococcus luteus ATCC 9341, Enterococcus faecalis ATCC 29212, Mycobacterium smegmatis ATCC 9341 and VRE.     

In vitro activities of antimicrobials against Brucella abortus isolates from cattle in Korea during 1998-2006

In vitro activities of 13 antibiotics were assessed against 85 Brucella abortus isolates from naturally infected cattle in the Republic of Korea during 1998-2006, using broth microdilution test. Tetracyclines showed the most excellent activity against B. abortus, displaying MIC values of 0.5 μg/ml or below. In particular, minocycline showed the lowest MIC??/?? values (0.125/0.125 μg/ml) in this study. Among four fluoroquinolones tested, ciprofloxacin (MIC??/??, 0.5/1 μg/ml) and norfloxacin (MIC??/??, 8/8 μg/ml) had the most and the least activities, respectively. Gentamicin (MIC??/??, 1/1 μg/ml) was more effective than streptomycin, erythromycin, rifampin, and chloramphenicol (MIC??/??, 2/2 μg/ml).     

Ciprofloxacin-1,2,3-triazole-isatin hybrids tethered via amide: Design,synthesis, and in vitro anti-mycobacterial activity evaluation

The purpose of this study was to prepare various novel amide tethered ciprofloxacin-1,2,3-triazole-isatin hybrids 7a-l, and evaluate their in vitro anti-mycobacterial activity as well as cytotoxicity in VERO cells. The synthesized hybrids showed considerable in vitro activity against both MTB H₃₇Rv and MDR-MTB with MIC of 0.12 to 32 μg/mL, and acceptable cytotoxicity in VERO cells (CC₅₀: 8.0–>128.0 μg/mL). In particular, the most active hybrid 7a (MIC_{MTB H37Rv}: 0.5 μg/mL and MIC_MDR-MTB: 0.12 μg/mL) had the activity in the same level with the first-line anti-tubercular agents isoniazid (MIC: 0.12 μg/mL) and rifampicin (MIC: 0.25 μg/mL), and it was 2-fold more active than the parent ciprofloxacin (MIC: 1.0 μg/mL) against MTB H₃₇Rv, and ≥16 folds more potent than ciprofloxacin (MIC: 2.0 μg/mL), isoniazid (MIC: >64 μg/mL) and rifampicin (MIC: >64 μg/mL) against MDR-MTB. Moreover, hybrid 7a (CC₅₀: 16.0 μg/mL) also displayed considerable cytotoxicity towards VERO cells. Thus, hybrid 7a could act as a platform for further investigations.     

Benzofuran-isatin hybrids tethered via different length alkyl linkers and their in vitro anti-mycobacterial activities

A series of novel benzofuran-isatin hybrids 6a–m tethered through different length alkyl linkers propylene, butylene, pentylene and hexylene were designed, synthesized and evaluated for their in vitro anti-mycobacterial activities against both drug-susceptible and multi-drug resistant (MDR) Mycobacterium tuberculosis (MTB) and cytotoxicity towards VERO cells. All hybrids with acceptable cytotoxicity in VERO cells (CC₅₀: 64 to >1024 μg/mL) also exhibited considerable anti-mycobacterial activities against both drug-susceptible and MDR-MTB strains with MIC in a range of 0.125–4 μg/mL. The SAR indicated that the length of the linker played a pivotal role on the activity, and the longer linker could enhance the activity. The most active hybrid 6d (MIC: 0.125 and 0.125 μg/mL) was comparable to or better than rifampicin (MIC: 0.5 μg/mL) and isoniazid (MIC: 0.06 μg/mL) against MTB H₃₇Rv, and was ≥256 folds more potent than rifampicin (MIC: 64 μg/mL) and isoniazid (MIC: >128 μg/mL) against MDR-MTB strain, but was less active than TAM16 (MIC: <0.06 μg/mL against the tested two strains). The hybrid 6d also showed low cytotoxicity towards VERO cell (CC₅₀: 128 μg/mL), but it was inferior to TAM16 in metabolic stability and in vivo pharmacokinetic profiles.     

Interaction of methylxanthines and gentamicin against Staphylococcus aureus and Pseudomonas aeruginosa: role of phosphodiesterase inhibition

Previous studies showed that methylxanthines increased the antimicrobial activity of gentamicin against Staphylococcus aureus and Pseudomonas aeruginosa. In this study, the effect of non-selective phosphodiesterase (PDE) inhibitors (methylxanthines: aminophylline and caffeine) and partially selective PDE inhibitors, dipyridamole and sildenafil, was evaluated on the antimicrobial activity of gentamicin using checkerboard method. Aminophylline at concentrations of 0.5 and 1 mg/ml reduced the minimal inhibitory concentration (MIC) of gentamicin (2 μg/ml) 2 and 4 times against S. aureus, and at concentrations of 0.5 and 2 mg/ml reduced the MIC of gentamicin (4 μg/ml) 2 and 4 times, respectively, against P. aeruginosa. Caffeine at concentrations of 1 and 2 mg/ml reduced the MIC of gentamicin (2 μg/ml) 4 and 32 times against S. aureus, and at concentrations of 0.12 and 2 mg/ml reduced the MIC of gentamicin (4 μg/ml) 2 and 4 times, respectively, against P. aeruginosa. However, dipyridamole and sildenafil (32 μg/ml) did not show any effect on MIC of gentamicin against S. aureus and P. aeruginosa. These results suggest that methylxanthines could increase gentamicin effects against S. aureus and P. aeruginosa but this effect is not mediated by inhibition of PDE 5, 6, 8, 10 and 11.     

Isolation and identification of antibacterial neo-compounds from the red ants of ChangBai Mountain, Tetramorium sp

Three novel coumarin compounds along with two known amide alkaloids were isolated from a methanol extract of the red ants of ChangBai Mountain, Tetramorium sp. Their structures were identified on the basis of IR, 2D NMR ((1)H-(1)H COSY, HSQC, HMBC and NOESY) and HRESIMS analysis. Antibacterial activity of all the compounds was evaluated using KB paper diffusion through measurement of inhibiting zone. It was found that four of all the compounds exhibited significant inhibitory activity against Gram-positive bacteria Bacillus subtilis with MIC values of 25 μg/ml (compounds 1-3) and 15 μg/ml (compound 4).     

Synergistic effects between silibinin and antibiotics on methicillin-resistant Staphylococcus aureus isolated from clinical specimens

Methicillin-resistant Staphylococcus aureus (MRSA) is a dangerous microorganism, and creates serious medical problems. It causes many types of infections in humans and often acquires multi-drug resistance. In this study, silibinin was evaluated against 20 clinical isolates of MRSA, either alone or in combination with ampicillin or oxacillin, using a checkerboard assay. The silibinin exhibited good activity against isolates of MRSA, and MRSA ATCC33952 and MSSA ATCC25923, with minimum inhibitory concentrations/minimum bactericidal concentrations (MICs/MBCs) ranging between 2-8/4-16 μg/mL, for ampicillin 2-1024/2-2048 μg/mL, and for oxacillin 0.25-32/0.5-64 μg/mL. The range of MIC(50) and MIC(90) were 0.5-4 μg/mL and 2-8 μg/mL, respectively. The MICs/MBCs for the combination of silibinin plus oxacillin or ampicillin were reduced by ≥4-fold against the MRSA isolates tested, demonstrating a synergistic effect, as defined by a fractional inhibitory concentration index (FICI) of ≤0.5. Furthermore, a time-kill study evaluating the growth of the tested bacteria showed that growth was completely attenuated after 2-5 h of treatment with the 1/2 MIC of silibinin, regardless of whether it was administered alone or with oxacillin (1/2 MIC) or ampicillin (1/2 MIC). In conclusion, silibinin exerted synergistic effects when administered with oxacillin or ampicillin and the antibacterial activity and resistant regulation of silibinin against clinical isolates of MRSA might be useful in controlling MRSA infections.     

In vitro inhibitory activity of sertraline against clinical isolates of Sporothrix schenckii

BackgroundSertraline (SRT) is an antidepressant that has proven its activity in vitro against Cryptococcus, Coccidioides, Trichosporon and other fungi. Disseminated sporotrichosis, although rare, has a high mortality and its treatment is difficult and prolonged, often relying in combining two or more antifungals.AimsIn our study we evaluate the antifungal activity of SRT, alone and in combination with itraconazole (ITC), voriconazole (VRC) and amphotericin B (AMB), against 15 clinical isolates of Sporothrix schenckii.MethodsWe used the broth microdilution method as described by the CLSI to test the susceptibility to antifungals, and the checkerboard microdilution method to evaluate drug interactions.ResultsThe minimum inhibitory concentration (MIC) with SRT was in the range of 4–8 μg/ml, while for AMB, VRC and ITC were 0.5–4 μg/ml, 0.5–8 μg/ml and 0.125–2 μg/ml, respectively. In addition, SRT showed synergy with ITC in one strain, mainly additivity with VRC, and indifference with AMB in others.ConclusionsThe MIC values with SRT for the isolates studied show the potential role of this drug as an adjuvant in the treatment of sporotrichosis, especially in disseminated or complicated cases.     

Antimicrobial effect of Korean propolis against the mutans streptococci isolated from Korean

The aim of this study was to determine the optimal concentration of Korean propolis against clinical isolates of mutans streptococci (MS) from Koreans. The antimicrobial activity was evaluated using the minimum inhibitory concentration (MIC) and time-kill curves against mutans streptococci. The MIC(90) values of propolis for MS were 35 μg/ml. Propolis had a bacteriostatic effect on Streptococcus mutans ATCC 25175(T) and bactericidal effects on Streptococcus sobrinus ATCC 33478(T) at > 2 × MIC (70 μg/ml). These results suggest that the propolis can be used in the development of oral hygiene products for the prevention of dental caries.     

In-vitro activity of 5-fluorocytosine against 1,021 Spanish clinical isolates of Candida and other medically important yeasts

The aim of this study was to determine the prevalence of primary resistance to 5-fluorocytosine (5FC) among clinical isolates of yeasts in Spain where this drug is not currently available for therapy. We have tested the in vitro activity of 5FC against 1,021 recent yeast clinical isolates, including 522 Candida albicans, 140 Candida parapsilosis, 68 Candida glabrata, 41 Candida dubliniensis, 50 Candida guilliermondii, 34 Candida tropicalis, 28 Candida krusei, 20 Candida famata, 11 Cryptococcus neoformans, 5 Cryptococcus albidus, 43 Rhodotorula spp., 24 Trichosporon spp., 5 Saccharomyces cerevisiae, 9 Pichia spp., and 21 isolates from other 11 yeast species. The MICs were determined by the ATB Fungus agar microdilution test (bioMerieux, France) and the following interpretive breakpoints were used: susceptible, > 4 microg/ml; intermediate, 8 to 16 microg/ml; resistant, > 32 microg/ml. 5FC was very active against Candida spp. and other medically important yeasts as 852 (83.4%) of the studied isolates were susceptible (MIC < 4 microg/ml). The species most susceptible to 5FC were C. dubliniensis (100%of isolates; MIC90, 0.25 microg/ml), C. famata (100% of isolates; MIC90, 0.25 microg/ml), C. guilliermondii (98%of isolates; MIC90, 0.25 microg/ml), C. glabrata (95.5% of isolates; MIC90, 0.25 microg/ml), and C. neoformans (90.9% of isolates; MIC90, 2 microg/ml). Primary resistance to 5FC was very uncommon, and a MIC > 32 microg/ml, indicator of in vitro resistance, was observed in 106 isolates (10.4%): 77 C. albicans (16.5% of isolates; MIC90, > 128 microg/ml), 9 C. parapsilosis (6.4% of isolates; MIC90, 8 microg/ml), 4 C. albidus (80% of isolates, MIC50, > 128 microg/ml), 3 C. glabrata (4.4% of isolates; MIC90, 0.25 microg/ml), 3 C. tropicalis (8.8% of isolates; MIC90, 4 microg/ml), 2 C. krusei (7.1% of isolates; MIC90, 8 microg/ml), 2 Rhodotorula spp. (4.6% of isolates, MIC90, 1 microg/ml), 8 Trichosporon spp. (33.3% of isolates; MIC90, 64 microg/ml), and 1 C. lipolytica (50% of isolates). Interestingly, most C. albicans (67 out of 77 isolates) resistant to 5FC were serotype B isolates.     

呼吸科住院患者耐碳青霉烯鲍曼不动杆菌抗菌药物敏感性及其分子特征

目的调查深圳市人民医院呼吸科住院患者耐碳青霉烯鲍曼不动杆菌（CRAB）的抗菌药物敏感性和耐药分子机制,以及克隆流行情况。方法收集2010年深圳市人民医院呼吸科住院患者临床分离CRAB29株,琼脂稀释法测定亚胺培南等15种抗菌药对CRAB的最低抑菌浓度（MIC）,PCR和DNA测序分析CRAB碳青霉烯酶基因型,脉冲场凝胶电泳（PFGE）分析菌株同源性。结果多粘菌素B对29株CRAB抗菌活性最强,敏感性100％,MIC50／MIC90为1／1μg/mL,其次米诺环素,敏感性96．6％,MIC50／MIC90为4／4μg/mL,替加环素中介率高达96．6％,MIC50／MIC90为4／4μg/mL。96．6％（28／29）CRAB携带ISAba1—blaOXA-23-like,对亚胺培南和美罗培南高度耐药,亚胺培南和美罗培南的MIC集中分布在32—64μg／mL;1株携带ISAba1—blaOXA-51-like CRAB,对亚胺培南和美罗培南中度耐药,亚胺培南和美罗培南的MIC分别为4μg/mL和8μg/mL。29株CRAB未发现blaOXA-24-like、blaOXA-143-like、金属酶基因及KPC酶基因。29株CRAB经PFGE分型共分2型,以A型28株（96．6％）为主要流行克隆,均携带ISAba1-blaOXA-23-like。结论2010年我院呼吸科临床分离CRAB主要携带ISAba1—blaOXA-23-like基因,并以克隆播散流行。     

Synthesis and antifungal activity of a novel series of 13-(4-isopropylbenzyl)berberine derivatives

By replacing the methyl group of 13-(4-isopropylbenzyl)berberine 2 with various acyl, alkyl, and benzyl groups via the demethylated intermediate, 13-(4-isopropylbenzyl)berberrubine 4, a novel series of 9-O-alkyl-13-(4-isopropylbenzyl)berberine derivatives was synthesized and examined for antifungal activities against various human pathogenic fungi. The introduction of various alkyl groups led to enhanced antifungal activity but that of acyl groups resulted in decrease of the activity. Among them, 9-O-butyl-13-(4-isopropylbenzyl)berberine 6d exhibited the most potent antifungal activities against Cryptococcus neoformans, Candida species (MIC=0.25-1 μg/ml), and Aspergillus species (MIC=2-4 μg/ml). The compound was found to be relatively safe up to 900 mg/kg in oral administration to mice.     

Peptides with antimicrobial and anti-inflammatory activities that have therapeutic potential for treatment of acne vulgaris

The pathogenesis of acne vulgaris is multifactorial involving infection of the pilosebaceous unit with Propionibacterium acnes and a cytokine-mediated inflammatory response. Five frog skin-derived antimicrobial peptides ([D4k]ascaphin-8, [G4K]XT-7, [T5k]temporin-DRa, brevinin-2GU, and B2RP-ERa), chosen for their low hemolytic activity against human erythrocytes, were assessed for their effects on the growth of clinical isolates of P. acnes and on the release of pro-inflammatory and anti-inflammatory cytokines from peripheral blood mononuclear (PBM) cells. All peptides inhibited the growth of P. acnes with the highest potency exhibited by [D4k]ascaphin-8 (minimum inhibitory concentration, MIC=3-12.5 μM). Release of TNF-α from concanavalin A (ConA)-stimulated PBM cells was significantly reduced by [D4k]ascaphin-8, [G4K]XT-7, brevinin-2GU, and B2RP-ERa (1 and 20 μg/ml) and by [T5k]temporin-DRa (20 μg/ml). Release of IFN-γ from unstimulated PBM cells was significantly reduced by [D4k]ascaphin-8 and brevinin-2GU (1 and 20 μg/ml). No peptide showed significant effects on Il-17 release. Release of the anti-inflammatory cytokines TGF-β, IL-4, and IL-10 from both unstimulated and ConA-treated PBM cells was significantly increased by [T5k]temporin-DRa and B2RP-ERa (1 and 20μg/ml). The potent activities of [D4k]ascaphin-8 and [T5k]temporin-DRa in inhibiting the growth of P. acnes and the release of pro-inflammatory cytokines, and in stimulating the release of anti-inflammatory cytokines suggest a possible therapeutic role in the treatment of acne vulgaris.     

泊沙康唑对临床来源接合菌的体外抗菌活性研究

目的研究泊沙康唑对临床来源的接合菌体外抗菌活性。方法对临床来源的43株接合菌采用ITS区序列分析进行准确鉴定,采用E-test纸片法研究泊沙康唑对43株菌的体外药物敏感性,观察其MIC值。结果经ITS序列分析鉴定,43株临床来源接合菌中最为常见的是小孢根霉和不规则毛霉(各12株),其次为米根霉(10株),ramosa(3株)。其他菌种分别为ornata、总状共头霉、微小根毛霉、卷曲毛霉、印度毛霉和冻土毛霉各1株。E-test纸片法测得泊沙康唑对毛霉属、根霉属和Lichtheimia spp.的MIC值范围分别为0.19～>32μg/mL、0.19～3μg/mL、0.002～0.38μg/mL,对总状共头霉和微小根毛霉的MIC值分别为1μg/mL和0.19μg/mL。结论泊沙康唑对大部分接合菌有效,不同种属MIC值范围不同,毛霉属真菌的MIC值差异较大。     

Complete genome sequence of highly multidrug-resistant Pseudomonas aeruginosa NCGM2.S1, a representative strain of a cluster endemic to Japan

We report the completely annotated genome sequence of Pseudomonas aeruginosa NCGM2.S1, a representative strain of a cluster endemic to Japan with a high level of resistance to carbapenem (MIC ≥ 128 μg/ml), amikacin (MIC ≥ 128 μg/ml), and fluoroquinolone (MIC ≥ 128 μg/ml).     

Susceptibilities to Amphotericin B, Fluconazole and Voriconazole of Trichosporon Clinical Isolates

A total of 35 Trichosporon isolates were collected from the Taiwan Surveillance of Antimicrobial Resistance of Yeasts (TSARY) project from 1999 to 2006, and their identifications as well as drug susceptibilities were determined. The most frequently isolated species was T. asahii (62.9%), and the most common clinical sample that yielded Trichosporon isolates was urine (37.1%). The etiology of all seven invasive trichosporonosis was T. asahii. For the 22 T. asahii isolates, the MIC(50) and MIC(90) for amphotericin B were 0.25 and 1 μg/mL, respectively. Those for fluconazole were 2 and 4 μg/mL, respectively, and for voriconazole 0.031 and 0.063 μg/mL, respectively. When the intraclass correlation coefficients (ICCs) and agreements were calculated, we found that the MICs of fluconazole obtained from different methods were similar and the inter-method discrepancies were low. Nevertheless, no unanimous MIC of amphotericin B and voriconazole was obtained among different methods.     

In vitro activity of a new triazole antifungal agent,Sch 56592, against clinical isolates of filamentous fungi

Sch 56592 is a new triazole derivative that possesses potent, broad-spectrum antifungal activity. We evaluated the in vitroactivity of Sch 56592 compared with that of itraconazole, amphotericin B and 5-fluorocytosine against 51 clinical isolates of filamentous fungi, including Aspergillus flavus(10), A. fumigatus(12), Fusariumspp. (13), Rhizopus spp. (6), Pseudallescheria boydii(5), and one isolate each of Acremoniumspp., A. niger, A. terreus, Paecilomycesspp., and Trichodermaspp. In vitrosusceptibility testing was performed using the microdilution broth method outlined in the NCCLS 27-A document. Sch 56592 was highly active against A. flavus(MIC₉₀, 0.25 μg/ml), A. fumigatus(MIC₉₀, 0.12 μg/ml), P. boydii(MIC₅₀, 1 μ/ml) and Rhizopusspp (M1C₅₀, 1 μg/ml). By comparison with itraconazole, Sch 56592 was four- to eight-fold more active against isolates of Aspergillusand both compounds showed equipotent in vitroactivity against P. boydiiand Rhizopusspp. Sch 56592 was four- to 16-fold more active than amphotericin B against Aspergillusspp. and P. boydiiand both antifungal drugs displayed similar activity against Rhizopusspp. Overall, Sch 56592 showed good in vitroactivity against all isolates tested (MIC, ≤ 2 μg/ml) except isolates of Fusarium(MIC range, 1–>4 μg/ml). On the basis of these data Sch 56592 has promising activity against Aspergillus spp. and other species of filamentous fungi that are likely to be encountered clinically. Additional in vitroand in vivostudies are warranted. This revised version was published online in June 2006 with corrections to the Cover Date.     

Molecular typing and antimicrobial susceptibility of Clostridium perfringens from broiler chickens

Clostridium perfringens (Cp) causes necrotic enteritis disease in commercial poultry. Antimicrobials are used to control and treat this disease and sometimes clinical outbreaks do not respond well to certain treatments. This study was designed to isolate Cp from clinical cases, type these isolates by multiplex PCR, and determine their antimicrobial susceptibility by micro-dilution method. A total of 67 Cp isolates were obtained from 155 broiler chicken flocks. All isolates were classified as type A and non-enterotoxin producers. Lincomycin, erythromycins, and tilmicosin showed very high minimal inhibitory concentration (MIC) 50 of ≥256 μg/ml. However, tylosin, amoxicillin, ampicillin, penicillin, florfenicol, danofloxacin, enrofloxacin, chlortetracycline, doxycycline, and oxytetracycline had variable MIC?? of 64, 0.5, 1, 1, 8, 4, 8, 4, 8, 0.5 μg/ml, respectively. It is recommended that Cp infections in Jordan be treated with either penicillins or tetracyclines especially amoxicillin and oxytetracycline.     

In Vitro Antibiotic Susceptibilities of Borrelia Isolates from Erythema Migrans Lesion of Lyme Disease Patients in Japan

Antibiotic susceptibilities of twelve borrelial isolates from skin of patients with erythema migrans (EM) and ticks (Ixodes persulcatus and I. ovatus) in Japan were examined by in vitro microdilution MIC method and macrodilution MBC method. Nine EM isolates and 3 tick isolates were susceptible to amoxicillin, erythromycin, and minocycline. MICs for Japanese isolates were 0.038–0.30 μg/ml, < 0.012 μg/ml, and < 0.012–0.05 μg/ml, respectively. MBCs were as follows: 0.038–0.88 μg/ml, < 0.012–0.10 μg/ml, and <0.025–0.78 μg/ml, respectively. These antibiotics could be recommended for treatment of patients in early stage of Lyme disease in Japan.