In Vitro Activity of Carbenicillin Against Gram-negative Bacilli

The activity of a new semisynthetic penicillin, carbenicillin, was determined against 241 strains of gram-negative bacilli with the tube-dilution technique. Of 143 strains of Pseudomonas sp., 99 had a minimal inhibitory concentration of 200 to 300 mug/ml. The majority of strains of Escherichia coli and Proteus spp. were sensitive to this antibiotic, with minimal inhibitory concentrations of 25 mug/ml or less. Strains of Klebsiella sp. were quite resistant to carbenicillin. The size of inoculum had no significant effect on the minimal inhibitory concentration for Pseudomonas sp.     

植物提取物对霉菌的抑制作用

以生活环境中常见的霉菌(青霉、米曲霉和黑曲霉)为试验菌,选取可能对其有抑制作用的植物,通过对其有机成分进行粗提,用滤纸片法筛选对上述霉菌有抑制效果的植物。经查阅相关文献,得备选植物共25种,试验后发现黄连抑制作用最强,其次是丁香和黄芩,最后对这3种中草药植物的最低抑菌浓度进行定量测定。     

In Vitro and In Vivo Activity of Hamycin Against Blastomyces dermatitidis

Clinical responses of patients with blastomycosis to treatment with hamycin have been variable. An explanation for this was sought in a series of studies in which in vitro and in vivo susceptibilities to hamycin of five strains of Blastomyces dermatitidis were compared. Minimal inhibitory concentrations of hamycin for the five strains indicated uniformly high levels of in vitro susceptibility (0.008 to 0.016 μg/ml). In vivo activity was measured in infected mice treated intraperitoneally for a period of 28 days with doses of the drug ranging from 0.001 to 0.030 mg per mouse. Significant differences in response to treatment among the five strains were noted (P < 0.001), and protective doses were found to vary from 0.001 to >0.030 mg per mouse per day. Further observations of infected mice after treatment revealed marked rates of relapsing infection, and several strains caused death. Persistent inapparent infections were also detected on culture of selected organs. Toxicity due to hamycin alone was not observed. These results suggest that variations in clinical responses to hamycin therapy in treatment of blastomycosis reflect differences in pathogenesis and host response in vivo to the infecting organism rather than differences in susceptibility of B. dermatitidis to hamycin.     

In Vitro Antifungal Activity of Dihydroxyacetone Against Causative Agents of Dermatomycosis

Dihydroxyacetone (DHA), a three-carbon sugar, is the browning ingredient in commercial sunless tanning formulations. DHA preparations have been used for more than 50 years and are currently highly popular for producing temporary pigmentation resembling an ultraviolet-induced tan. In this work, the in vitro antifungal activity of dihydroxyacetone was tested against causative agents of dermatomycosis, more specifically against dermatophytes and Candida spp. The antifungal activity was determined by the broth microdilution method according to the Clinical and Laboratory Standards Institute guidelines for yeasts and filamentous fungi. The data obtained show that the fungicidal activity varied from 1.6 to 50 mg ml⁻¹. DHA seems to be a promising substance for the treatment of dermatomycosis because it has antifungal properties at the same concentration used in artificial suntan lotions. Therefore, it is a potential low-toxicity antifungal agent that may be used topically because of its penetration into the corneal layers of the skin.     

Nystatin-Intralipid Preparation: Characterization and In Vitro Activity Against Yeasts and Molds

The objective of our studies is the development of a novel formulation of nystatin (NYT) that could be administered systemically and might be used for therapy of invasive mycoses. We developed a formulation of nystatin and intralipid (IL), which is a clinically used food supplement, and this report focuses on the characterization of NYT-IL, assessment of its antifungal activity and in vitro toxicity. We characterized physical properties of the NYT-IL preparation and its stability during storage. Susceptibility of Candida, Aspergillus and Fusarium species was determined using a CLSI technique. In vitro toxicity of NYT-IL was assessed using an assay measuring hemolysis of sheep red blood cells (SRBC) and leakage of potassium. It was found that: (1) the particle size in NYT-IL did not differ from that of IL; (2) over 80% of NYT was in association with IL; and (3) these features did not change during storage. All Candida and Aspergillus strains had lower minimal inhibitory concentration (MIC) values for NYT-IL than that for NYT; the MICs of the Fusarium strains were similar for NYT & NYT-IL. Toxicity assays showed that the NYT-IL formulation is less toxic than NYT. In conclusion, we describe a novel, characterized, stable formulation of nystatin, nystatin-intralipid, with in vitro activity against pathogenic Candida and Aspergillus species.     

In Vitro Activity of Mitochondrial ATP Synthetase Inhibitors Against Plasmodium falciparum

ABSTRACT. The mitochondrion appears to be essential for the growth of asexual, intraerythrocytic stages of Plasmodium falciparum and may thus be a suitable chemotherapeutic target. The in vitro activity of almitrine, a mitochondrial ATP synthetase inhibitor used for the treatment of hypoxemia, was compared with other mitochondrial inhibitors against chloroquine-susceptible and chloroquine-resistant P. falciparum using an isotopic semimicro drug susceptibility assay. The 50% inhibitory concentration (IC50) values of almitrine (range: 2.6–19.8 μM) were within similar range of values of other mitochondrial ATP synthetase inhibitors and doxycycline, a mitochondrial protein synthesis inhibitor. Almitrine was equally active against chloroquine-susceptible and chloroquine-resistant parasites. Drug combination studies showed no interaction between chloroquine and almitrine. Our results suggest that almitrine, a clinically safe drug, may represent a lead compound with a specific target against the mitochondrial ATP synthetase which may be useful for antimalarial chemotherapy.     

Improved Microscopy of Mycoplasma In Vitro

Techniques were developed for continuous microscopic observation of mycoplasmata growing in vitro in Rose chambers by using an inverted phase microscope. The methods permitted direct microscopic observation of undisturbed growth of mycoplasmata in liquid medium. Inocula of mycoplasmata were passed through 0.22-mum filters before culture to provide a suspension of discrete particles. The sequential growth of Mycoplasma pneumoniae was followed from points or single straight lines, with development of branching, a net-like confluence of filaments, large bodies occurring in the center of developing colonies, and finally coccoid forms. Other species of Mycoplasma which did not attach as readily to glass could be observed also by inverted phase microscopy. Umbonation of colonies (a "friedegg" appearance) occurred in liquid medium, indicating that this appearance was not due simply to interaction with the agar medium, but may reflect a qualitative difference in growth patterns between center and periphery. For growth on solid medium, direct observation of colonies in uncovered plates of agar medium was made by using inverted phase microscopy. This was found helpful in detecting small colonies and in observing relationships between colonies.     

In Vitro Antifungal Activity of Micafungin and Caspofungin Against Dermatophytes Isolated from China

Aims

The aims of this study are to investigate the in vitro activities of micafungin and caspofungin that are two new echinocandin antifungal drugs against clinically isolated dermatophytes in China and to define MEC (minimal effective concentration) as the reading endpoints of this study in accordance with (Clinical and laboratory Standards Institute) CLSI M38-A2 reference.

Methods

Minimal effective concentrations (MECs) of micafungin and caspofungin for 82 dermatophyte strains were determined according to CLSI (formerly NCCLS) M38-A2 broth microdilution methods.

Results

(1) The MEC_90s of micafungin for Trichophyton violaceum and Trichophyton tonsurans were 0.25 μg/mL, and for Microsporum canis and Trichophyton verrucosum were 0.06 μg/mL. The MEC_90s for Trichophyton rubrum, Trichophyton mentagrophytes, Microsporum gypseum and Epidermophyton floccosum were 0.03 μg/mL. (2) The MEC_90s of caspofungin for T. rubrum, T. violaceum and T. tonsurans were 1 μg/mL, and for T. mentagrophytes, M. canis, M. gypseum, E. floccosum and T. verrucosum were 0.5 μg/mL. (3) Compared with caspofungin, micafungin demonstrated lower MEC value to dermatophytes (P < 0.05).

Conclusions

Micafungin has stronger in vitro antifungal activity than caspofungin.     

In Vitro Activity of a New Antifungal Azolyl-substituted Indole Against Aspergillus fumigatus

A new 2- (α -azolylbenzyl)indole derivative exhibited high in vitro activity against 10 strains of Aspergillus fumigatus. This active compound, MT18n, had MIC of 2 μg/mL and is slightly less active than itraconazole and amphotericin B. The mechanism of action of this compound was evaluated through scanning electron microscopy, ergosterol biosynthesis inhibition and phospholipase A 2 -like activity inhibition studies. Scanning electron microscopy allowed observation of the membrane perturbations caused by MT18n and inference of a critical role of MT18n in membrane synthesis inhibition. Like other azole derivatives MT18n inhibits ergosterol biosynthesis, with a minimal inhibitory concentration of 6 μM. On the other hand, MT18n (10 μM) decreased the secreted phospholipase A 2 -like activity of Aspergillus fumigatus, an enzyme involved in the invasion process of the host. These results show the high in vitro activity of MT18n against Aspergillus fumigatus and suggest that this compound disturbs the membrane structure via ergosterol biosynthesis inhibition and exhibits phospholipase activity inhibition.     

Effect of Inoculum Size on In Vitro Susceptibility Testing with Lincomycin

There is disagreement in the literature as to whether lincomycin is primarily a bacteriostatic or a bactericidal agent against gram-positive cocci and also regarding the levels of activity of this agent against susceptible microorganisms. These questions were examined in a study of the effect of inoculum size on the results of tube dilution susceptibility determinations with lincomycin against 49 clinical isolates of Staphylococcus aureus and 25 strains of streptococci and pneumococci. Lincomycin was both highly active and bactericidal when tested against 40 strains of S. aureus with inocula containing a maximum of 10(4) cells per ml [median minimal inhibitory concentration (MIC), 0.78 mug/ml; median minimal bactericidal concentration (MBC), 1.56 mug/ml]. With inocula of 10(5) cells per ml, lincomycin was primarily bacteriostatic (median MIC, 1.56 mug/ml; median MBC, 12.5 mug/ml). There were further decreases in inhibitory levels and significant losses of bactericidal activity when inocula containing more than 10(7) cells were tested (median MIC, 3.13 mug/ml; median MBC > 100 mug/ml). Similar measurements with streptococci and pneumococci revealed a lesser effect of inoculum size. The mean MBC value for alpha-hemolytic streptococci increased from 0.40 to 1.05 mug/ml with an increase in inocula from 10(4) to 10(6) cells per ml, but without a marked increase in MIC values. Similar results were obtained for beta-hemolytic streptococci and pneumococci.     

In Vitro Activity of Coumermycin A1 Against Mycobacterium tuberculosis var. hominis

Coumermycin A(1) exhibited in vitro activity against eight strains of Mycobacterium tuberculosis var. hominis. All eight strains were inhibited by levels of 2.5 mug/ml, and six of the eight strains were inhibited by levels of 0.3 mug/ml or less.     

Topical Formulations Containing Pimenta pseudocaryophyllus Extract: In Vitro Antioxidant Activity and In Vivo Efficacy Against UV-B-Induced Oxidative Stress

Pimenta pseudocaryophyllus is a Brazilian native plant that presents high concentrations of flavonoids and other polyphenolic compounds. Herein, we evaluated: (1) the chemical properties of P. pseudocaryophyllus ethanolic extract (PPE), (2) the in vitro antioxidant activity (AA) of PPE and of two different topical formulations (F1 and F2) containing PPE, (3) physico-chemical and functional stability, (4) in vitro release of PPE, and (5) in vivo capacity of formulations to prevent UV-B irradiation-induced skin damage. Results show that the polyphenol and flavonoid contents in PPE were 199.33 and 28.32 mg/g, respectively, and HPLC results show the presence of eugenol, tannic acid, and rutin. Evaluation of the in vitro AA of PPE demonstrated a dose-dependent effect and an IC₅₀ of 4.75 μg/mL in 2,2-diphenyl-1-picrylhydrazyl (DPPH) and 3.0 μg/mL in 2,2′-azinobis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) assays. The ferric-reducing antioxidant power (FRAP assay) was 0.046 μmol/L trolox equivalent/μg/mL of extract. Among the AA, only the capacity to scavenge DPPH radical of PPE was maintained in F1 and F2. In addition, both formulations satisfactorily released the extract. The evaluation of the functional stability of F1 and F2 did not demonstrate loss of activity by storage at room temperature and at 4°C/6 months. In irradiated mice, treatment with F1 and F2 added with PPE significantly increased the capacity to scavenge ABTS radical and the FRAP of skin compared to vehicle-treated mice. In conclusion, the present results suggest that formulations containing PPE may be a topical source of antioxidant compounds to decrease oxidative damages of the skin.     

In Vitro Development of Exoerythrocytic Forms of Plasmodium Gallinaceum Sporozoites In Avian Macrophages

ABSTRACT Exoerythrocytic forms of Plasmodium gallinaceum were cultured in vitro using salivary gland sporozoites extracted from experimentally infected Aedes fluviatilis mosquitoes. the host cells were macrophage precursors from chicken bone marrow. At various times after introduction of Sporozoites, the cultures were stained by Giemsa or by immunofluorescence assay (IFA) using anti-sporozoite-specific monoclonal antibodies (MAb). the time to complete parasite development in vitro was 50-70 h. By 70 h, ruptured segmenters and free merozoites were visible within the cells. Inoculation of normal chickens with infected cultures induced parasitemia after a pre-patent period of 10-11 days. In vitro young exoerythrocytic forms, late schizonts that include the matured segmenters, and free merozoites shared common antigens with the sporozoites as revealed by IFA using anti-sporozoite-specific MAbs. Our data indicate that macrophages support development of P. gallinaceum sporozoites and that the circumsporozoite proteins are present until Ac end of the primary exoerythrocytic schizogony.     

In Vitro Activity of Coumermycin A1

The in vitro activity of coumermycin A(1) was compared with that of novobiocin, ampicillin, and minocycline. Coumermycin was found to be the most active antibiotic of the four against Staphylococcus aureus. It was about 50 times more active than novobiocin or minocycline against the strains tested. Coumermycin also showed good activity against group A streptococci and pneumococci, moderate activity against Escherichia coli, indole-positive Proteus species, and Pseudomonas aeruginosa, and poor activity against Klebsiella-Enterobacter and enterococci. Against P. mirabilis, however, coumermycin activity was almost equal to that of ampicillin. The new antibiotic was further found to be greatly reduced in activity in the presence of plasma, but its minimal inhibitory concentration was not greatly affected by inoculum size. Coumermycin was found to be bacteriostatic in its action, and resistance to it developed slowly. Also, cross-resistance was present with novobiocin but absent with ampicillin or minocycline.     

The Effects of Environmental Conditions on the In Vitro Activity of Selected Antimicrobial Agents Against Escherichia coli

Various environmental conditions likely to be encountered at a nidus of infection were evaluated for their effect on selected classes of antimicrobial agents. The minimum inhibitory concentration (MIC) of several aminoglycosides (apramycin, kanamycin, gentamicin, tobramycin, amikacin), tetracycline, and chloramphenicol for five strains of E. coli were unchanged by temperature (35°–39.5°C), atmosphere (aerobic to anaerobic), pH > 7, NaCl concentration (up to 150 mM), zinc concentration (up to 50 mM), and manganese (up to 10 mM). However, the aminoglycoside MICs were increased up to fivefold at pH < 6.5. Magnesium and calcium ion concentrations >10 mM and ferric iron concentrations ≥10 mM increased aminoglycoside MICs from 3.66- to 8-fold. Tetracycline MICs were increased 1.2- to 6.5-fold when the concentration of magnesium or calcium was ≥10 mM. The results of this in vitro study might provide insight into the effects of local in vivo environmental conditions on several classes of antimicrobial agents. Received: 22 September 1997 / Accepted: 6 October 1997     

Cytoglobin Exhibits Anti-Fibrosis Activity on Liver In Vivo and In Vitro

Cytoglobin, generated using genetic engineering method, is a kind of recombinant human stellate cell activation-associated protein. We speculate that it could influence the development of hepatic fibrosis like Sellate cell activation-associated protein which was discovered by Kawada et al. Therefore, we investigated its anti-fibrosis effect on liver both in vivo and in vitro. During our research, we found that cytoglobin showed obvious effect compared with the control group on Thioacetamide-induced liver fibrosis in SD rats, including significantly decrease in aspartate aminotransferase, Hyaluronic acid, laminin and collagen I(Col I) levels in serum and hydroxyproline in livers, which are the important indices reflecting the degree of hepatic fibrosis. Meanwhile, the viability of rat hepatic stellate cell line T6 (HSC-T6) cells was inhibited by cytoglobin and the apoptosis induced by cytoglobin in HSC-T6 cells was detected by Annexin V/PI double staining. Activation of the caspase cascade including caspase-3 for the intrinsic pathways was demonstrated. The results also showed that the expression of Bcl-2 protein decreased whereas that of Bax protein increased, leading to an increase of the Bax/Bcl-2 ratio. Our results demonstrated that cytoglobin exhibited anti-fibrosis activity on livers in vivo and in vitro, involving apoptosis induction.