Geometric Mean MICs Research Articles

Amoxicillin for the secondary prevention of rheumatic fever in children not allergic to penicillin

Amoxicillin for the secondary prevention of rheumatic fever in children not allergic to penicillin To the Editor: In October 2014, a communication from the Department of Health substituted azithromycin for erythromycin for penicillin-allergic patients. This was for certain conditions including acute rheumatic fever and prophylaxis of rheumatic fever. It has recently been suggested that owing to the challenges with the availability of oral penicillin, azithromycin should be used as a penicillin substitute for patients who are not allergic to penicillin. In our opinion it is inappropriate to substitute a macrolide for another form of penicillin (amoxicillin) in this situation. The primary reason is that despite many decades of use, there is no significant group A beta-haemolytic streptococcal (GABHS) resistance to penicillin. There are, however, increasing reports of GABHS resistance to macrolides, and azithromycin in particular.[1-4] A previously reported randomised trial[5] of 125 mg phenoxymethylpenicillin (pen VK) or amoxicillin given three times a day for 10 days to children with GABHS pharyngitis demonstrated that the recurrence of the original GABHS within 21 days after the end of therapy was higher with pen VK (20%) than with amoxicillin (13%). The geometric mean minimum inhibitory concentrations for amoxicillin and pen VK against 88 isolates of GABHS were 0.008 and 0.009 μg/mL, respectively. The mean concentrations of amoxicillin and pen VK in sera after 125 mg doses were 3.86 μg/ mL and 1.74 μg/ mL, respectively. In this study, therefore, amoxicillin was active against Gram-positive organisms at an inhibitory level similar to that of pen VK, but had higher blood levels. This study suggests that amoxicillin is probably at least as good as pen VK for the treatment of GABHS pharyngitis. We therefore recommend, as per the South African Essential Drugs List, benzathine penicillin 600 000 units for children <30 kg and 1.2 million units for children ≥30 kg by intramuscular injection every 28 days for the secondary prevention of rheumatic fever. If it is not advisable to use an intramuscular form of penicillin (for example with a patient on warfarin), then in the absence of pen VK and in the absence of penicillin allergy, children weighing <20 kg should be given amoxicillin 125 mg twice daily, and children weighing ≥20 kg given 250 mg twice daily. There is no defined azithromycin paediatric dosage for the secondary prevention of rheumatic fever in penicillin allergy. Azithromycin has however been dosed long term in clinical trials in children with cystic fibrosis.[6-8] There is no consensus on the dosage, but there is some support[6-9] for 250 mg once daily (<40 kg) or 500 mg once daily (≥40 kg) three times a week (Monday, Wednesday and Friday). We recommend that azithromycin is used for the secondary prevention of rheumatic fever only in children who are allergic to penicillin and is dosed 250 mg (<40 kg) or 500 mg (≥40 kg), once a day three times a week (Monday, Wednesday and Friday).

The Investigational Fungal Cyp51 Inhibitor VT-1129 Demonstrates Potent In Vitro Activity against Cryptococcus neoformans and Cryptococcus gattii.

Thein vitroactivities of the novel fungal Cyp51 inhibitor VT-1129 were evaluated against a large panel ofCryptococcus neoformansandCryptococcus gattiiisolates. VT-1129 demonstrated potent activities against bothCryptococcusspecies as demonstrated by low MIC50and MIC90values. ForC. gattii, thein vitropotency was maintained against all genotypes. In addition, significantly lower geometric mean MICs were observed for VT-1129 than for fluconazole againstC. neoformans, including isolates with reduced fluconazole susceptibility.

The novel arylamidine T-2307 demonstrates in vitro and in vivo activity against echinocandin-resistant Candida glabrata.

Candida species are major causes of invasive mycoses in immunocompetent and immunocompromised hosts. Treatment options are limited in the setting of antifungal resistance and increased rates of echinocandin-resistant Candida glabrata have been reported. The novel arylamidine T-2307 demonstrates potent in vitro antifungal activity against Candida species. Our objective was to evaluate the in vitro and in vivo activity of T-2307 against resistant C. glabrata. In vitro activity was determined against 42 clinical C. glabrata isolates, including 17 echinocandin-resistant strains. Neutropenic ICR mice were inoculated intravenously with an echinocandin-resistant C. glabrata isolate (T-2307; caspofungin MICs ≤0.008 and 0.5 mg/L, respectively). Therapy with vehicle control, T-2307 (0.75, 1.5, 3 or 6 mg/kg subcutaneously once daily) or caspofungin (1 or 10 mg/kg intraperitoneally once daily) began 1 day post-challenge. Kidneys were collected on day 8 and fungal burden was assessed by counting cfu. T-2307 demonstrated potent in vitro activity against C. glabrata (geometric mean MIC 0.0135 mg/L), which was maintained against echinocandin-resistant isolates (geometric mean MIC 0.0083 mg/L). T-2307 also demonstrated in vivo efficacy in mice infected with echinocandin-resistant C. glabrata. Significant reductions in fungal burden were observed at each dosage level of T-2307 compared with control. Reductions in fungal burden were also observed with high-dose caspofungin. T-2307 demonstrated potent in vitro activity against C. glabrata, including echinocandin-resistant isolates, which translated into in vivo efficacy against invasive candidiasis caused by an echinocandin-resistant C. glabrata strain. These results demonstrate the potential for T-2307 as therapy against echinocandin-resistant Candida.

Plasmid-Mediated OqxAB Is an Important Mechanism for Nitrofurantoin Resistance in Escherichia coli.

Increasing consumption of nitrofurantoin (NIT) for treatment of acute uncomplicated urinary tract infections (UTI) highlights the need to monitor emerging NIT resistance mechanisms. This study investigated the molecular epidemiology of the multidrug-resistant efflux gene oqxAB and its contribution to nitrofurantoin resistance by using Escherichia coli isolates originating from patients with UTI (n = 205; collected in 2004 to 2013) and food-producing animals (n = 136; collected in 2012 to 2013) in Hong Kong. The oqxAB gene was highly prevalent among NIT-intermediate (11.5% to 45.5%) and -resistant (39.2% to 65.5%) isolates but rare (0% to 1.7%) among NIT-susceptible (NIT-S) isolates. In our isolates, the oqxAB gene was associated with IS26 and was carried by plasmids of diverse replicon types. Multilocus sequence typing revealed that the clones of oqxAB-positive E. coli were diverse. The combination of oqxAB and nfsA mutations was found to be sufficient for high-level NIT resistance. Curing of oqxAB-carrying plasmids from 20 NIT-intermediate/resistant UTI isolates markedly reduced the geometric mean MIC of NIT from 168.9 μg/ml to 34.3 μg/ml. In the plasmid-cured variants, 20% (1/5) of isolates with nfsA mutations were NIT-S, while 80% (12/15) of isolates without nfsA mutations were NIT-S (P = 0.015). The presence of plasmid-based oqxAB increased the mutation prevention concentration of NIT from 128 μg/ml to 256 μg/ml and facilitated the development of clinically important levels of nitrofurantoin resistance. In conclusion, plasmid-mediated oqxAB is an important nitrofurantoin resistance mechanism. There is a great need to monitor the dissemination of this transferable multidrug-resistant efflux pump.

In Vitro and In Vivo Antimicrobial Activities of Minocycline in Combination with Azithromycin, Clarithromycin, or Tigecycline against Pythium insidiosum.

The present study investigated the in vitro and the in vivo interactions among azithromycin, clarithromycin, minocycline, and tigecycline against Pythium insidiosum. In vitro antimicrobial activities were determined by the broth microdilution method in accordance with CLSI document M38-A2, and the antibiotic interactions were assayed using the checkerboard MIC format. In vivo efficacy was determined using a rabbit infection model. The geometric mean MICs of azithromycin, clarithromycin, minocycline, and tigecycline against P. insidiosum were, respectively, 1.91, 1.38, 0.91, and 0.79 μg/ml. By checkerboard testing, all combinations resulted in in vitro synergistic interactions (>60%). Antagonism was not observed. The in vivo studies showed that azithromycin (20 mg/kg/day twice daily) alone or in combination with minocycline (10 mg/kg/day twice daily) significantly decreased the fungal burden. This study demonstrates that azithromycin possesses potent curative efficacy against subcutaneous pythiosis in the rabbit model.

Anti-Pseudomonas aeruginosa activity of 1,10-phenanthroline-based drugs against both planktonic- and biofilm-growing cells.

The beneficial antimicrobial properties of 1,10-phenanthroline (phen)-based drugs, together with the imperative need to develop new chemotherapeutic options for prevention/treatment of infections caused by MDR Gram-negative bacteria, led us to evaluate the effects of phen, 1,10-phenanthroline-5,6-dione (phendione), [Ag(phendione)2]ClO4 and [Cu(phendione)3](ClO4)2·4H2O on planktonic- and biofilm-growing Pseudomonas aeruginosa. Thirty-two non-duplicated Brazilian clinical isolates of P. aeruginosa with distinct genetic backgrounds were used in all experiments. The effect of test compounds on planktonic bacterial proliferation was determined as recommended by CLSI protocol. The effect on biofilm formation was evaluated by crystal violet incorporation (biomass determination) and XTT (viability assay). Mature biofilm disorganization was evidenced by staining with crystal violet. Phen-based compounds presented anti-P. aeruginosa activity, but with different potencies concerning the geometric mean MIC: [Cu(phendione)3](2+) (7.76 μM) > [Ag(phendione)2](+) (14.05 μM) > phendione (31.15 μM) > phen (579.28 μM). MICs of each compound were similar irrespective of whether the P. aeruginosa isolates were susceptible or resistant to classical antimicrobials (ceftazidime, meropenem and imipenem). The pretreatment of bacteria with phen, phendione and phendione's metal derivatives at 0.5 × MIC value inhibited biofilm formation, particularly the use of [Cu(phendione)3](2+) and [Ag(phendione)2](+), which significantly reduced both biomass (48% and 44%, respectively) and viability (78% and 77%, respectively). The compounds studied also disrupted mature biofilm in a dose-dependent manner, especially [Ag(phendione)2](+) and [Cu(phendione)3](2+) (IC50, 9.39 and 10.16 μM, respectively). Coordination of phendione to Ag(+) and Cu(2+) represents a new promising group of anti-infective agents, which revealed a potent anti-P. aeruginosa action against both planktonic- and biofilm-growing cells.

In Vitro Susceptibility Profiles of Eight Antifungal Drugs against Clinical and Environmental Strains of Phaeoacremonium.

In vitro susceptibilities of a worldwide collection of molecularly identified Phaeoacremonium strains (n = 43) belonging to seven species and originating from human and environmental sources were determined for eight antifungal drugs. Voriconazole had the lowest geometric mean MIC (0.35 μg/ml), followed by posaconazole (0.37 μg/ml), amphotericin B (0.4 μg/ml), and isavuconazole (1.16 μg/ml). Caspofungin, anidulafungin, fluconazole, and itraconazole had no activity.

In Vitro Activities of Eight Antifungal Drugs against a Global Collection of Genotyped Exserohilum Isolates.

The in vitro susceptibilities of 24 worldwide Exserohilum isolates belonging to 10 species from human and environmental sources were determined for eight antifungal drugs. The strains were characterized by internal transcribed spacer (ITS) sequencing and amplified fragment length polymorphism fingerprinting. Posaconazole had the lowest geometric mean MIC (0.16 μg/ml), followed by micafungin (0.21 μg/ml), amphotericin B (0.24 μg/ml), itraconazole (0.33 μg/ml), voriconazole (0.8 μg/ml), caspofungin (1.05 μg/ml), isavuconazole (1.38 μg/ml), and fluconazole (15.6 μg/ml).

In vitro and in vivo antidermatophytic activities of some Iranian medicinal plants.

In the last decades, the number of people suffering from dermatophytoses has seriously increased, which may be due to the development of resistant strains to a range of antifungal drugs. The present study was aimed to evaluate the antidermatophytic properties of eight extracts from the selected spices and herbs, which were ethno-medicinally used in Iran against Trichophyton mentagrophytes, Trichophyton interdigitale, Microsporum canis, and Microsporum gypseum (10 strain of each). The in vitro antifungal activities of the extracts from four spices and four plants were evaluated by the broth macro dilution method against four dermatophyte strains. In addition, the in vivo therapeutic effects of Myrtus communis L. and Cinnamomum zeylanicum Blume extracts (the most active extracts) on dermatophytosis induced by M. canis and T. mentagrophytes in guinea pigs were evaluated. Results of in vitro antifungal assay revealed that all the tested extracts demonstrated both fungistatic and fungicidal activities with the geometric mean (GM) MIC ranging from 0.058 to 3.73 mg/ml and GM (MFC) ranging from 0.058 to 7.46 mg/ml, respectively. Two extracts (M. communis and C. zeylanicum) significantly inhibited the growth of all the tested dermatophytes, while other extracts demonstrated weak (MICs of >0.625 mg/ml) to moderate (MICs ranging from 100 to 0.625 mg/ml) activities. In vivo antidermatophytic assay demonstrated that clotrimazole cured T. mentagrophytes and M. canis infection on days 21 and 17, respectively, whereas M. communis and C. zeylanicum extracts significantly (p < 0.05) cured T. mentagrophytes and M. canis infection on days 9 and 13 as well as 9, 11, respectively. Phytochemical screening showed the presence of flavonoids, tannins, phenols, and alkaloids in M. communis and alkaloids, flavonoids, and tannins in C. zeylanicum. Findings of the present study also provided the scientific evidence that natural plants could be used in traditional medicine for the prevention and treatment of dermatophytic infections.

Molecular identification andin-vitroantifungal susceptibility testing of Candida species isolated from patients with onychomycosis.

Background and Purpose: Candida species are the most opportunistic fungi affecting the nails and resulting in onychomycosis. In this study, we identified and evaluated in-vitro susceptibility of the recovered isolates against fluconazole (FLC), voriconazole (VRC), and clotrimazole (CLT) using the Clinical and Laboratory Standards Institute (CLSI) M27-A3 document.Materials and Methods:From patients with either clinically or mycologically proven onychomycosis, 97 isolates comprising of seven Candida species were isolated, which were identified by both conventional and molecular techniques such as polymerase chain reaction-restriction fragment length polymorphism. In addition, Candida dubliniensis was confirmed by restriction endonuclease analysis. Antifungal susceptibility of each isolate against the three azoles applied in this study was determined using the CLSI microdilution reference method M27-A3. Results: Candida parapsilosis (C. parapsilosis) was the most frequently isolated species (n=44), followed by C. albicans (n=23), C. tropicalis (n=13), C. glabrata (n=7), C. krusei (n=6), C. guilliermondii (n=3), and C. dubliniensis (n=1). All the isolates were susceptible to CLT. VRC had lower minimum inhibitory concentration (MIC) values for the isolates compared to FLC. Geometric mean MIC values of VRC, FLC, and CLT for C. parapsilosis isolates were 0.07 μg/ml, 0.8 μg/ml, and 0.35 μg/ml, respectively. Collectively, all species exhibited greater susceptibility to VRC in comparison to C. albicans (P≤0.001).Conclusion:This study showed that non-albicans Candida species were the most common etiologic agents of non-dermatophyte onychomycosis. The major antifungal agents used in clinics to empirically treat yeast onychomycosis are FLC and CLT. Our data suggested that CLT is a better choice for the treatment of Candida onychomycosis, especially in drug resistant cases.

Comparison of antimicrobial susceptibilities of pharyngeal, rectal, and urethral Neisseria gonorrhoeae isolates among men who have sex with men.

U.S. surveillance for Neisseria gonorrhoeae antimicrobial susceptibilities is based exclusively on male urethral isolates. These data inform gonorrhea treatment guidelines, including recommendations for the treatment of extragenital infections, but data on the susceptibilities of extragenital isolates are limited. We compared the antimicrobial susceptibilities of pharyngeal, rectal, and urethral gonococcal isolates collected from men who have sex with men (MSM), at five sentinel sites throughout the United States. MICs were determined by the agar dilution method. Generalized linear models were used to compare (i) the proportions of isolates with elevated MICs and (ii) geometric mean MICs according to anatomic site, adjusted for city. In December 2011 to September 2013, totals of 205 pharyngeal, 261 rectal, and 976 urethral isolates were obtained. The proportions of isolates with elevated ceftriaxone MICs (≥ 0.125 μg/ml) did not differ according to anatomic site (0.5% of pharyngeal isolates, 1.5% of rectal isolates, and 1.7% of urethral isolates, with a city-adjusted odds ratio [aOR] of 0.4 [95% confidence interval {CI}, 0.0 to 3.9] for pharyngeal versus urethral isolates and an aOR of 0.9 [95% CI, 0.2 to 4.2] for rectal versus urethral isolates). The city-adjusted geometric mean ceftriaxone MICs of pharyngeal (0.0153 μg/ml) and rectal (0.0157 μg/ml) isolates did not differ from that of urethral isolates (0.0150 μg/ml) (ratios of geometric mean MICs of 1.02 [95% CI, 0.90 to 1.17] and 1.05 [95% CI, 0.93 to 1.19], respectively). Similar results were observed for other antimicrobials, including cefixime and azithromycin. These findings suggest that, at the population level, gonococcal antimicrobial susceptibility surveillance based on urethral isolates from MSM adequately reflects the susceptibilities of N. gonorrhoeae strains circulating among MSM.

Analysis of Neisseria gonorrhoeae azithromycin susceptibility in the United States by the Gonococcal Isolate Surveillance Project, 2005 to 2013.

Azithromycin, administered with ceftriaxone, is recommended by the CDC for the treatment of gonorrhea. Many experts have expressed concern about the ease with which Neisseria gonorrhoeae can acquire macrolide resistance. We sought to describe gonococcal azithromycin susceptibility in the United States and to determine whether azithromycin susceptibility has changed over time. We analyzed data from 2005 to 2013 from the Gonococcal Isolate Surveillance Project, a CDC-supported sentinel surveillance network that monitors gonococcal antimicrobial susceptibility. A total of 44,144 N. gonorrhoeae isolates were tested for azithromycin susceptibility by agar dilution methods. The overall azithromycin MIC50 was 0.25 μg/ml, and the MIC90 was 0.5 μg/ml. There were no overall temporal trends in geometric means. Isolates from men who had sex with men had significantly higher geometric mean MICs than isolates from men who had sex exclusively with women. The overall prevalence of reduced azithromycin susceptibility (MIC, ≥2 μg/ml) was 0.4% and varied by year from 0.3% (2006 and 2009) to 0.6% (2013). We did not find a clear temporal trend in gonococcal azithromycin MICs in the United States, and the prevalence of reduced azithromycin susceptibility remains low. These findings support the continued use of azithromycin in a combination therapy regimen for gonorrhea.

Luliconazole Demonstrates Potent In Vitro Activity against Dermatophytes Recovered from Patients with Onychomycosis

The in vitro activities of luliconazole, amorolfine, ciclopirox, and terbinafine were determined against 320 dermatophyte isolates from large toenails of onychomycosis patients enrolled into an ongoing phase 2b/3 clinical study. The geometric mean MIC for luliconazole was 0.00022 μg/ml against all isolates, compared to 0.0194 to 0.3107 μg/ml for the three other agents. The in vitro potency of luliconazole was maintained regardless of the dermatophyte species.

Antifungal Susceptibility Patterns of Opportunistic Fungi in the Genera Verruconis and Ochroconis

Species of Verruconis and species of Ochroconis are dematiaceous fungi generally found in the environment but having the ability to infect humans, dogs, cats, poultry, and fish. This study presents the antifungal susceptibility patterns of these fungi at the species level. Forty strains originating from clinical and environmental sources were phylogenetically identified at the species level by using sequences of the ribosomal DNA internal transcribed spacer (rDNA ITS). In vitro antifungal susceptibility testing was performed against eight antifungals, using the Clinical and Laboratory Standards Institute (CLSI) broth microdilution method. The geometric mean MICs for amphotericin B (AMB), flucytosine (5FC), fluconazole (FLC), itraconazole (ITC), voriconazole (VRC), and posaconazole (POS) and minimum effective concentrations (MECs) for caspofungin (CAS) and anidulafungin (AFG) across the Ochroconis and Verruconis species were as follows, in increasing order. For Verruconis species, the values (μg/ml) were as follows: AFG, 0.04; POS, 0.25; ITC, 0.37; AMB, 0.50; CAS, 0.65; VRC, 0.96; 5FC, 10.45; and FLC, 47.25. For Ochroconis species, the values (μg/ml) were as follows: AFG, 0.06; POS, 0.11; CAS, 0.67; VRC, 2.76; ITC, 3.94; AMB, 5.68; 5FC, 34.48; and FLC, 61.33. Antifungal susceptibility of Ochroconis and Verruconis was linked with phylogenetic distance and thermotolerance. Echinocandins and POS showed the greatest in vitro activity, providing possible treatment options for Ochroconis and Verruconis infections.

Linezolid Minimum Inhibitory Concentration (MIC) Creep in Methicillin-Resistant &lt;i&gt;Staphylococcus aureus&lt;/i&gt; (MRSA) Clinical Isolates at a Single Japanese Center

The aim of this study was to evaluate whether linezolid minimum inhibitory concentration (MIC) creep occurred in Staphylococcus aureus clinical isolates, including methicillin-resistant S. aureus (MRSA), over a recent 5-year period at a single Japanese center. A total of 453 MRSA and 195 methicillin-susceptible S. aureus (MSSA) isolates recovered from inpatients from April 1, 2008 to March 31, 2013 were analyzed. The MIC of linezolid was determined by automated Vitek-2 system. The modal MIC, MIC range, MIC50 and MIC90 (MICs required to inhibit the growth of 50% and 90% of organisms, respectively), geometric mean MIC and percentages of susceptible and resistant isolates were evaluated for each fiscal year. None of the S. aureus isolates were resistant to linezolid. Isolates with an MIC of >1 µg/mL were more common in the MSSA samples than in the MRSA samples (91.3% versus 38.2%, p<0.001). The linezolid geometric mean MIC increased by 0.403 µg/mL (from 1.178 in 2008 to 1.582 in 2012) in the MRSA isolates (p=0.006, r(2)=0.945 according to a linear regression analysis) over the 5-year period; however, no increase was observed in the MSSA isolates. The frequency of MRSA isolates with an MIC of 1 µg/mL decreased (from 76.3% in 2008 to 35.4% in 2012) and the isolates with MICs of >1 µg/mL increased over time (from 23.7% in 2008 to 64.6% in 2012). This report demonstrates the occurrence of linezolid MIC creep, as determined using the geometric mean MIC, in MRSA clinical isolates at a single Japanese center.

Molecular Characterization and In Vitro Antifungal Susceptibility of Candida Glabrata Clinical Isolates with Reduced Echinocandin Susceptibility and High Level Multi-Azole Resistance

Candida glabrata is the second most commonly isolated yeast recovered from blood cultures in the United States. We characterized 85 C. glabrata clinical isolates recovered from various clinical specimens obtained from immunocompromised individuals. This collection was unique because it included a series of isolates recovered from the blood of a patient who only partially responded to antifungal therapy. In vitro activity of caspofungin, micafungin, anidulafungin, fluconazole, voriconazole and amphotericin B was evaluated. Most of the isolates were susceptible to the echinocandins, triazoles and amphotericin B. The geometric mean MIC of the antifungals for the susceptible isolates (n=79) were as follows: caspofungin, 0.061315 ± 0.076934; micafungin, 0.123521 ± 0.457202; anidulafungin, 0.044158 ± 0.895249; fluconazole, 7.013461 ± 20.56794; voriconazole, 0.324939 ± 1.051247; amphotericin B, 0.474923 ± 0.162994. Five of the six serial blood isolates showed a reduced echinocandin susceptibility (RES) to the echinocandins and the triazoles. Characterization of the hot spot 1 region of FKS1, FKS2 and FKS3 showed no amino acid alterations. However, the genes coding for the drug efflux proteins CgCDR1, CgCDR2, CgSNQ2, as well as Cgcyp51 were over-expressed in the isolates with RES and azole resistance compared to the susceptible isolates, indicating that the upregulation of the synthesis of efflux proteins and the drug target is responsible for conferring resistance to triazoles in these isolates. These results demonstrate that multiechinocandin and multi-azole resistant C. glabrata clinical isolates can emerge under the selection pressure imposed by specific drug therapy over a relatively short period of time.

Evaluation of anti-Candida activity of Vitis vinifera L. seed extracts obtained from wine and table cultivars.

For the first time, grape seed extracts (GSEs), obtained from wine and table cultivars of Vitis vinifera L., cultured in experimental fields of Lazio and Puglia regions of Italy and grown in different agronomic conditions, have been tested on 43 Candida species strains. We demonstrated a significant correlation between the content of the flavan-3-ols in GSEs extracts, with a polymerization degree ≥4, and anti-Candida activity. Moreover, we demonstrated that GSEs, obtained from plants cultured with reduced irrigation, showed a content of polymeric flavan-3-ols >250 mg/g with geometric mean MIC values between 5.7 and 20.2 mg/L against Candida albicans reference strains. GSE, showing 573 mg/g of polymeric flavan-3-ols, has been tested in an experimental murine model of vaginal candidiasis by using noninvasive in vivo imaging technique. The results pointed out a significant inhibition of Candida albicans load 5 days after challenge. These findings indicate that GSEs with high content of polymeric flavan-3-ols can be used in mucosal infection as vaginal candidiasis.

Multidrug-resistant endemic clonal strain of Candida auris in India

Candida auris is a recently described rare agent of fungemia. It is notable for its antifungal resistance. A total of 15 C. auris isolates, originating from seven cases of fungemia, three cases of diabetic gangrenous foot, and one case of bronchopneumonia from a tertiary care hospital in south India, were investigated. All of the 15 isolates were identified by sequencing and 14 of these along with 12 C. auris isolates previously reported from two hospitals in Delhi, north India, two each from Japan and Korea were genotyped by amplified fragment length polymorphism (AFLP). In vitro antifungal susceptibility testing (AFST) was done by the Clinical and Laboratory Standards Institute (CLSI) broth microdilution method. Candida auris isolates were misidentified as Candida haemulonii by VITEK. All were resistant to fluconazole [geometric mean minimum inhibitory concentration (MIC) 64 μg/ml] and 11 isolates were resistant to voriconazole (MIC ≥1 μg/ml). Forty-seven percent of the C. auris isolates were resistant to flucytosine (MIC ≥64 μg/ml) and 40% had high MIC (≥1 μg/ml) of caspofungin. Breakthrough fungemia developed in 28.6% of patients and therapeutic failure in 4 (66.7%) patients. Interestingly, the 26 Indian C. auris isolates from north and south India were clonal and phenotypically and genotypically distinct from Korean and Japanese isolates. The present study demonstrates that C. auris is a potential emerging pathogen that can cause a wide spectrum of human mycotic infections. The prevalence of a C. auris endemic clonal strain resistant to azoles and other antifungals in Indian hospitals with high rates of therapeutic failure in cases of fungemia is worrisome.

The frequency of BRO β-lactamase and its relationship to antimicrobial susceptibility and serum resistance in Moraxella catarrhalis

We investigated the frequency of BRO β-lactamase and its relationship to antibiotic susceptibility profiles and serum susceptibility. Moraxella catarrhalis clinical isolates (n=197) were collected from patients with respiratory tract infections in Tokyo between November 2004 and April 2005. Phenotypic and genotypic detection of β-lactamases was performed. The MICs of 6 antibiotics were determined by Etest, and the serum bactericidal assay was conducted by using the culture-and-spot test. Nearly all (192; 97%) of the clinical isolates were β-lactamase producers; of these, 182 (95%) were bro-1 and 10 (5%) were bro-2 positive. MIC50, MIC90, and geometric mean MICs of penicillin, amoxicillin, cefixime, and clarithromycin for BRO-1 isolates were significantly higher than for BRO-2 isolates. The frequency of intermediate and full serum resistance was significantly higher in BRO-1 isolates than in BRO-2 isolates (P=0.0056), but not BRO-negative isolates (P=0.1333). We provide the first evidence that the presence of BRO-1 in M.catarrhalis is associated with reduced susceptibility to clarithromycin and β-lactam antibiotics, as well as serum non-sensitive (intermediate and resistant).

Antimicrobial susceptibility and mechanisms of high-level macrolide resistance in clinical isolates of Moraxella nonliquefaciens

We investigated antimicrobial susceptibility and the molecular mechanism involved in conferring high-level macrolide resistance in 47 clinical isolates of Moraxella nonliquefaciens from Japan. Antimicrobial susceptibility was determined using Etest and agar dilution methods. Thirty-two erythromycin-non-susceptible strains were evaluated for the possibility of clonal spreading, using PFGE. To analyse the mechanism related to macrolide resistance, mutations in the 23S rRNA gene and the ribosomal proteins, and the presence of methylase genes were investigated by PCR and sequencing. The efflux system was examined using appropriate inhibitors. Penicillin, ampicillin, amoxicillin, cefixime, levofloxacin and antimicrobials containing β-lactamase inhibitors showed strong activity against 47 M. nonliquefaciens isolates. Thirty-two (68.1 %) of the 47 isolates showed high-level MICs to macrolides (MIC ≥128 mg l(-1)) and shared the A2058T mutation in the 23S rRNA gene. The geometric mean MIC to macrolides of A2058T-mutated strains was significantly higher than that of WT strains (P<0.0001). Thirty-two isolates with high-level macrolide MICs clustered into 30 patterns on the basis of the PFGE dendrogram, indicating that the macrolide-resistant strains were not clonal. In contrast, no common mutations of the ribosomal proteins or methylase genes, or overproduction of the efflux system were observed in A2058T-mutated strains. Moreover, of the 47 M. nonliquefaciens strains, 43 (91.5 %) were bro-1 and 4 (8.5 %) were bro-2 positive. Our results suggest that most M. nonliquefaciens clinical isolates show high-level macrolide resistance conferred by the A2058T mutation in the 23S rRNA gene. This study represents the first characterization of M. nonliquefaciens.