Dose-dependent Susceptibility Research Articles

Impact of Cefepime Susceptible-Dose-Dependent MIC for Enterobacteriaceae on Reporting and Prescribing.

The CLSI cefepime breakpoints were revised to include a susceptible-dose-dependent (SDD) category for Enterobacteriaceae, with the intention that higher cefepime doses be used for these isolates. In this study, 1.6% of Enterobacteriaceae isolates were reported as SDD, with Escherichia coli the most common SDD organism. Cefepime was prescribed in three cases (4.8%); the majority of SDD isolates were treated with a carbapenem. Enterobacteriaceae with cefepime SDD MICs were not commonly treated with cefepime at our institution.

What does the susceptible-dose dependent interpretive category for cefepime in ESBL-producing bacteria?

In this study, we investigated the frequency of isolates included in the susceptible-dose dependent (SDD) category, according to the Clinical and Laboratory Standards Institute guidelines, carrying blaTEM, blaSHV and blaCTX genes among 92 Klebsiella pneumoniae and 80 Enterobacter cloacae clinical isolates. The presence of one or more extended-spectrum β-lactamases (ESBLs) genes was observed in 64% K. pneumoniae and 69% E. cloacae isolates. Nineteen isolates were included in SDD interpretive category criteria, of which 15 carried ESBL genes (seven K. pneumoniae and eight E. cloacae). Considering the high proportion of ESBL gene-containing isolates included in the SDD category (79%), we recommend that physicians exercise caution in the use of cefepime for treatment of infections caused by these isolates, reducing possible therapeutic failure, particularly in cases of ESBL-producing bacterial strains.

Population Pharmacokinetic Assessment and Pharmacodynamic Implications of Pediatric Cefepime Dosing for Susceptible-Dose-Dependent Organisms.

The Clinical and Laboratory Standards Institute (CLSI) revised cefepime (CFP) breakpoints forEnterobacteriaceaein 2014, and MICs of 4 and 8 μg/ml were reclassified as susceptible-dose dependent (SDD). Pediatric dosing to provide therapeutic concentrations against SDD organisms has not been defined. CFP pharmacokinetics (PK) data from published pediatric studies were analyzed. Population PK parameters were determined using NONMEM, and Monte Carlo simulation was performed to determine an appropriate CFP dosage regimen for SDD organisms in children. A total of 664 CFP plasma concentrations from 91 neonates, infants, and children were included in this analysis. The median patient age was 1.0 month (interquartile range [IQR], 0.2 to 11.2 months). Serum creatinine (SCR) and postmenstrual age (PMA) were covariates in the final PK model. Simulations indicated that CFP dosing at 50 mg/kg every 8 h (q8h) (as 0.5-h intravenous [i.v.] infusions) will maintain free-CFP concentrations in serum of >4 and 8 μg/ml for >60% of the dose interval in 87.1% and 68.6% of pediatric patients (age, ≥30 days), respectively, and extending the i.v. infusion duration to 3 h results in 92.3% of patients with free-CFP levels above 8 μg/ml for >60% of the dose interval. CFP clearance (CL) is significantly correlated with PMA and SCR. A dose of 50 mg/kg of CFP every 8 to 12 h does not achieve adequate serum exposure for older children with serious infections caused by Gram-negative bacilli with a MIC of 8 μg/ml. Prolonged i.v. infusions may be useful for this population.

Distribution and antifungal susceptibility of Candida species in patients with increased risk for fungal infections

Candida species are opportunistic yeasts that can be a serious threat for immunocompromised and critically ill patients, and a cause for increased morbidity and mortality in hospitalized patients. The aim of this study was to determine the frequency and distribution of different Candida species in clinical specimens in patients with increased risk for fungal infections, and to determine the antifungal susceptibility profile of invasive Candida species to antifungal agents. During a two year period, clinical specimens from 120 patients divided into 4 groups were analysed at the Institute of microbiology and parasitology, Faculty of Medicine, Skopje, Republic of Macedonia. Each of these 4 groups consisted of specimens from 30 patients, with primary immune deficiency, critically ill patients treated in the intensive care units (ICU), patients with mucosal candidiasis only, and patients with cystic fibrosis. All specimens were investigated with conventional mycological methods. Identification of Candida species was performed with VITEK-2 system (bioMérieux, France). E-test strips of fluconazole, voriconazole, amphotericin B and caspofungin (AB bioMerieux, France) were used for determination of the antifungal susceptibility profile. In this study, a total of 115 isolates of Candida species were confirmed in different clinical specimens (91 isolates from mucosal surfaces and 24 isolates from blood culture). Colonisation of mucosal membranes of gastrointestinal, respiratory and/or urinary tracts was registered in 56.67% (17/30), 56.67% (17/30), 90% (27/30) and 100% (30/30) of the specimens in the first, second, third and fourth group respectively. In all four groups of patients, the following Candida species were confirmed: C. albicans - 55%, C. glabrata - 17.6%, C. parapsilosis - 7.7%, C. tropicalis - 6.6%, unidentified Candida species - 4.4%, C. dubliniensis - 3.3%, C. kefyr - 2.2%, and one isolate of C. rugosa, C. pelliculosa and C. krusei each. Positive blood culture was registered in 23.33% specimens from the first group, 43.33% in the second group, 23.08% of the third group, and in one specimen of the fourth group. The most frequent isolates from blood culture were C. tropicalis and C. krusei, followed by C. albicans, C. parapsilosis and C. tropicalis, and in the second group C. albicans and C. pelliculosa were equally distributed, followed by C. parapsilosis and C. glabrata. All invasive isolates of Candida species were susceptible to amphotericin B, voriconazole and caspofungin. Resistance to fluconazole was registered in 8.3% (2/24) of all confirmed Candida species. Dose-dependent susceptibility to fluconazole was confirmed in 46% (11/24) of the isolates. Our study confirms high prevalence of colonisation and candidemia with non-albicans Candida species. Resistance to antifungal agents was registered only in two isolates of C. krusei. An epidemiological study is necessary for surveillance of dynamics of candidemia and antifungal susceptibility profile of invasive isolates of Candida species in our patients.

Cefepime Therapy for Monomicrobial Enterobacter cloacae Bacteremia: Unfavorable Outcomes in Patients Infected by Cefepime-Susceptible Dose-Dependent Isolates

A new category of cefepime susceptibility, susceptible dose dependent (SDD), for Enterobacteriaceae, has been suggested to maximize its clinical use. However, clinical evidence supporting such a therapeutic strategy is limited. A retrospective study of 305 adults with monomicrobial Enterobacter cloacae bacteremia at a medical center from 2008 to 2012 was conducted. The patients definitively treated with in vitro active cefepime (cases) were compared with those treated with a carbapenem (controls) to assess therapeutic effectiveness. The 30-day crude mortality rate is the primary endpoint, and clinical prognostic factors are assessed. Of 144 patients receiving definitive cefepime or carbapenem therapy, there were no significant differences in terms of age, sex, comorbidity, source of bacteremia, disease severity, or 30-day mortality (26.4% versus 22.2%; P = 0.7) among those treated with cefepime (n = 72) or a carbapenem (n = 72). In the multivariate analysis, the presence of critical illness, rapidly fatal underlying disease, extended-spectrum beta-lactamase (ESBL) producers, and cefepime-SDD (cefepime MIC, 4 to 8 μg/ml) isolates was independently associated with 30-day mortality. Moreover, those infected by cefepime-SDD isolates with definitive cefepime therapy had a higher mortality rate than those treated with a carbapenem (5/7 [71.4%], versus 2/11 [18.2%]; P = 0.045). Cefepime is one of the therapeutic alternatives for cefepime-susceptible E. cloacae bacteremia but is inefficient for cases of cefepime-SDD E. cloacae bacteremia compared with carbapenem therapy.

Nosocomial candidiasis in Rio de Janeiro State: Distribution and fluconazole susceptibility profile.

One hundred and forty-one Candida species isolated from clinical specimens of hospitalized patients in Rio de Janeiro, Brazil, during 2002 to 2007, were analized in order to evaluate the distribution and susceptibility of these species to fluconazole. Candida albicans was the most frequent species (45.4%), followed by C. parapsilosis sensu lato (28.4%), C. tropicalis (14.2%), C. guilliermondii (6.4%), C. famata (2.8%), C. glabrata (1.4%), C. krusei (0.7%) and C. lambica (0.7%). The sources of fungal isolates were blood (47.5%), respiratory tract (17.7%), urinary tract (16.3%), skin and mucous membrane (7.1%), catheter (5.6%), feces (2.1%) and mitral valve tissue (0.7%). The susceptibility test was performed using the methodology of disk-diffusion in agar as recommended in the M44-A2 Document of the Clinical and Laboratory Standards Institute (CLSI). The majority of the clinical isolates (97.2%) was susceptible (S) to fluconazole, although three isolates (2.1%) were susceptible-dose dependent (S-DD) and one of them (0.7%) was resistant (R). The S-DD isolates were C. albicans, C. parapsilosis sensu lato and C. tropicalis. One isolate of C. krusei was resistant to fluconazole. This work documents the high susceptibility to fluconazole by Candida species isolated in Rio de Janeiro, Brazil.

Antifungal susceptibility in vitro determined by the Etest® for Candida obtained from the oral cavity of irradiated and elderly individuals.

This study aimed to evaluate the in vitro antifungal susceptibility of Candida species of head-and-neck-irradiated patients (Group 1), non-institutionalized (Group 2) and institutionalized elders (Group 3) using Etest® methodology. Candida was isolated from saliva and presumptively identified by CHROMagar Candida(r), confirmed by morphological criteria, carbohydrate assimilation (API 20C AUX®) and genetic typing (OPE 18). The collection was made from 29, 34 and 29 individuals (Groups 1, 2 and 3, respectively) with 67 isolates. Etest® strips (ketoconazole, itraconazole, fluconazole, amphotericin B and flucytosine) on RPMI (Roswell Park Memorial Institute) agar, on duplicate, were used to evaluate susceptibility. ATTC (American Type Culture Collection) 10231 (Candida albicans) was used as quality control. Among the 67 isolates of Candida species, most were susceptible to azoles, flucytosine and amphotericin B. None of the isolates showed resistance and dose-dependent susceptibility to amphotericin B. There were nine strains resistant to itraconazole, six to fluconazole and two to ketoconazole and ten dose-dependent, mainly to flucytocine. The highest MIC (minimum inhibitory concentration) to C. albicans, C. tropicalis, C. parapsilosis was 2.671 μg.mL-1, 8.104 μg.mL-1, 4.429 μg.mL-1, all for flucytosine. C. krusei and C. glabrata were associated with higher MIC for azoles and C. glabrata with higher MIC to flucytosine. In summary, susceptibility to all tested antifungal agents was evident. The isolates were more resistant to itraconazole and dose-dependent to flucytosine. A comparison of C. albicans in the three groups showed no outliers. Higher MIC was associated with C. krusei and C. glabrata.

Evaluation of clinical outcomes in patients with Gram-negative bloodstream infections according to cefepime MIC

Predicted and observed failures at higher cefepime MICs have prompted the Clinical and Laboratories Standards Institute (CLSI) to lower the susceptible breakpoint for Enterobacteriaceae to ≤2mg/L, with dose-dependent susceptibility at 4–8mg/L, while the susceptibility breakpoint for nonfermentative organisms remain unchanged at ≥8mg/L. The contribution of increasing cefepime MIC to mortality risk in the setting of aggressive cefepime dosing is not well defined. Patients who were treated with cefepime for Gram-negative blood stream infections (GNBSIs), including both Enterobacteriaceae and nonfermentative organisms, were screened for inclusion in this retrospective cohort study. Demographic and microbiologic variables were collected, including pathogen, cefepime MIC, dosage, and interval. The objective was to define a risk-adjusted mortality breakpoint for cefepime MICs. Secondarily, we looked at time to death and length of stay (LOS) postculture. Ninety-one patients were included in the analysis. Overall, 19 patients died and 72 survived. Classification and Regression Tree analysis identified an inhospital mortality breakpoint at a cefepime MIC between 2 and 4mg/L for patients with a modified Acute Physiology and Chronic Health Evaluation II score ≤16.5 (4.2% versus 25%, respectively). Multivariate logistic regression revealed increased odds of mortality at a cefepime MIC of 4mg/L (adjusted odds ratio [aOR] 6.47; 95% confidence interval [CI] 1.25–33.4) and 64mg/L (aOR 6.54, 95% CI 1.03-41.4). Those with cefepime MICs ≥4mg/L experienced a greater median intensive care unit LOS for survivors (16 versus 2days; P=0.026). Increasing cefepime MIC appears to predict inhospital mortality among patients who received aggressive doses of cefepime for GNBSIs, supporting a clinical breakpoint MIC of 2mg/L.

In vitro antifungal activities of Euphorbia macroclada and fluconazole against pathogenic Candida species.

Background and Purpose: Candida species constitute an important group of opportunistic fungi, which cause various clinical diseases. Considering the resistance of some Candida species to conventional antifungal agents, treatment of such cases may be challenging and complicated. The purpose of this study was to evaluate and compare the antifungal activities of Euphorbia macroclada latex and fluconazole against different Candida species.Materials and Methods:A total of 150 Candida isolates including C. albicans (n=77), C. glabrata (n=28), C. parapsilosis (n=23), C. tropicalis (n=15), C. krusei (n=4), C. famata (n=1), C. kefyr (n=1) and C. inconspicua (n=1) were included in this study. In vitro antifungal activities of Euphorbia macroclada latex and fluconazole against these Candida species were evaluated, according to M27-A2 protocol on broth macrodilution method by the Clinical and Laboratory Standards Institute (CLSI). Results:Among 150 Candida isolates, 98 isolates (65.33%), i.e., C. albicans (n=41), C. glabrata (n=23), C. tropicalis (n=12) and C. parapsilosis (n=22) with minimal inhibitory concentration (MIC) ≤ 8 μg/ml were susceptible to fluconazole. Resistance to fluconazole was noted in 15 isolates, i.e., C. albicans (n=10), C. glabrata (n=2), C. krusei (n=1), C. kefyr (n=1), and C. inconspicua (n=1), with MICs of 64 µg/ml. The remaining isolates (n=37) including C. albicans (n=26), C. glabrata (n=3), C. tropicalis (n=3), C. parapsilosis (n=1), C. krusei (n=3) and C. famata (n=1) with MIC= 16-32 µg/ml showed dose-dependent susceptibility. The latex of Euphorbia macroclada was able to inhibit the growth of 30 out of 150 tested Candida isolates with MIC range of 128-512 µg/ml. These isolates were as follows: C. albicans (n=2), C. glabrata (n=4), C. parapsilosis (n=19), C. krusei (n=2) and C. tropicalis (n=3). Compared to other isolates, higher MIC values were noted for C. albicans and C. glabrata (512 µg/ml), respectively.Conclusion:The latex of Euphorbia macroclada showed notable antifungal activities against some pathogenic Candida species. Therefore, it can be potentially used as an alternative antifungal agent in future. However, further research is required to identify its active components.

Impact of Revised Cefepime CLSI Breakpoints on Escherichia coli and Klebsiella pneumoniae Susceptibility and Potential Impact If Applied to Pseudomonas aeruginosa

The CLSI reduced the cefepime Enterobacteriaceae susceptibility breakpoint and introduced the susceptible-dose-dependent (S-DD) category. In this study, MICs were determined for a Gram-negative collection to assess the impact of this change. For Enterobacteriaceae, this resulted in <2% reduction in susceptibility, with 1% being S-DD. If applied to Pseudomonas aeruginosa, the % susceptibility (%S) dropped from 77% to 43%, with 34% being S-DD. The new breakpoints did little to the Enterobacteriaceae %S, but for P. aeruginosa, a profound reduction was seen in %S. The recognition of a S-DD response to cefepime should alert clinicians to the possible need for higher doses.

Susceptibility of Cryptococcus neoformans and Cryptococcus gattii from clinical and environment sources in Nairobi, Kenya

Objective : To determine anti-fungal susceptibility of Cryptococcus neoformans and Cryptococcus gattii from environmental and clinical sources in Nairobi, Kenya. Design : Prospective study. Setting : Kenya Medical Research Institute, Mycology laboratory, Nairobi, Kenya. Subjects : A total of 123 isolates were tested for their susceptibility to fluconazole (FLC), amphotericin B(AMP) and fluorocytosine (5FC). Clinical isolates were 70(66 Cryptococcus neoformans and 4 Cryptococcus gattii ) while environmental isolates were 53(41 C. neoformans and 12 C. gattii ). The isolates were characterised using various phenotypic tests including microscopic morphology, physiological and biochemical tests (API 20 Caux), pigmentation on bird seed agar and reaction on canavanineglycine- bromthymolblue agar. European Committee on Anti-microbial Susceptibility Standards (EUCAST) was used as the reference method for susceptibility testing. Results : Most C. neoformans isolates; clinical (61/66; 92.4%) and environmental (38/41; 92.7%) were susceptible to FLC. The number of C. neoformans isolates inhibited at susceptible dose dependent (SDD) range (16-32μg/ml) by FLC were clinical (4/66; 6.1%) and environmental (2/41; 4.9%). One C. neoformans isolate each; clinical (1/66; 1.5%) and environmental (1/41; 2.4%) was resistant to FLC. All C. gatti isolates from clinical and environmental were fully susceptible to FLC. The percentage of C. neoformans isolates that were susceptible (S) (MIC ≤ 1.0 μg/ml) to AMP were; clinical(52/66; 90.2%) and environmental (37/41; 78.8%) while the rest were susceptible dose dependent (SDD) with MIC (2-8μg/ml). Reduced susceptibilities to 5FC was displayed in all clinical and environmental C. neoformans and C. gatii isolates; for instance resistance to 5FC was reported in C. neoformans ; clinical (8/66; 12.1%) and environmental (1/41; 2.4 %). Among the C. gattii isolates there was also decreased susceptibility to 5FC with Minimum Inhibition Concentration (MIC) range of between 0.5-32 μg/ml. There were no significant differences in susceptibility ranges among all the clinical and environmental isolates. Conclusion : This study demonstrated reduced susceptibilities among C. neoformans and C. gattii isolates to commonly used anti-fungal drugs.

Investigation of ERG11 gene expression among fluconazole-resistant Candida albicans: first report from an Iranian referral paediatric hospital

ABSTRACTThe multiplicity of mechanisms of resistance to azole antifungal agents has been described. As fluconazole- resistant clinical Candida albicans isolates that constitutively over-express ERG11 have been identified in previous studies, the aim of this study is to investigate this molecular mechanism involved in fluconazole resistance of C. albicans clinical isolates. Fluconazole susceptibility testing was carried out on clinical isolates of Candida spp. obtained from hospitalised children in an Iranian referral children's hospital. A polymerase chain reaction (PCR)-restriction fragment length polymorphism (RFLP) technique was used to differentiate Candida spp. The resistant C. albicans isolates were subjected to RT-qPCR using primers that identify ERG11 gene expression. Of the 142 Candida spp. isolates studied, C. albicans was the most predominant isolate, occurring in 68.3% (97/142) of the patients. According to the CLSI method, the majority of the C. albicans isolates (91.7%, 89/97), categorised as susceptible (minimum inhibitory concentration [MIC] ≤8 μg/mL), five isolates were considered resistant (MIC ≥64 μg/mL) and three had dose-dependent susceptibility (MIC=8.16–32 μg/mL). The ERG11 gene in the five fluconazole-resistant C. albicans isolates was upregulated 4.15–5.84-fold relative to the ATCC 10231 control strain. In this study, the expression of ERG11 was upregulated in all the fluconazole-resistant C. albicans isolates. There are limited data on the antifungal susceptibility of Candida spp. as well as the molecular mechanism of azole resistance in Iran, especially for isolates causing infections in children. Therefore, the surveillance of antifungal resistance patterns and investigation of other mechanisms of azole resistance in all Candida spp. isolates is recommended.

Diversity and antifungal resistance patterns of prevalent opportunistic pathogenic yeasts colonizing the oral cavities of asymptomatic human immunodeficiency virus-infected individuals, and their relation to CD4(+) counts.

Yeasts are important opportunistic pathogens, in individuals infected with human immunodeficiency virus (HIV). Yeast species inhabiting the oral mucosa of HIV-infected persons can act as source of oral lesions, especially as the individual progresses towards immunocompromised state. Present study was conducted to evaluate the diversity of yeasts in oral cavities of asymptomatic HIV-infected persons and their association with CD4(+) cell counts. 100 HIV seropositive subjects and 100 healthy controls were screened for oral yeast carriage using standard procedures. Of the 100 HIV-seropositive persons screened, 48 were colonized by different yeasts, either alone or in association with another species. Candida albicans was the most common species (56.90%) while non C. albicans Candida (NCAC) accounted for 39.65%. Among NCAC, Candida tropicalis and Candida krusei were most common. One isolate each of rare opportunistic pathogenic yeasts, Geotrichum candidum and Saccharomyces cereviseae, was recovered. The control group had an oral candidal carriage rate of 23%; C. albicans was the predominant species, followed by Candida glabrata, C. tropicalis and Candida parapsilosis. Antifungal susceptibility testing revealed no resistance in C. albicans, to the commonly used antifungal agents, whereas resistance or dose dependent susceptibility to fluconazole was observed in some of the NCAC species. Oral carriage of opportunistic pathogenic yeasts was greater in HIV-seropositive persons heading towards immunocompromised state, as evidenced by their CD4(+) cell count. The predominant yeast isolated in this study (C. albicans), was found to be susceptible to commonly used antifungals.

Diversity and antifungal resistance patterns of prevalent opportunistic pathogenic yeasts colonizing the oral cavities of asymptomatic human immunodeficiency virus-infected individuals, and their relation to CD4+ counts

Background:Yeasts are important opportunistic pathogens, in individuals infected with human immunodeficiency virus (HIV). Yeast species inhabiting the oral mucosa of HIV-infected persons can act as source of oral lesions, especially as the individual progresses towards immunocompromised state. Present study was conducted to evaluate the diversity of yeasts in oral cavities of asymptomatic HIV-infected persons and their association with CD4+ cell counts.Materials and Methods:100 HIV seropositive subjects and 100 healthy controls were screened for oral yeast carriage using standard procedures.Results:Of the 100 HIV-seropositive persons screened, 48 were colonized by different yeasts, either alone or in association with another species. Candida albicans was the most common species (56.90%) while non C. albicans Candida (NCAC) accounted for 39.65%. Among NCAC, Candida tropicalis and Candida krusei were most common. One isolate each of rare opportunistic pathogenic yeasts, Geotrichum candidum and Saccharomyces cereviseae, was recovered. The control group had an oral candidal carriage rate of 23%; C. albicans was the predominant species, followed by Candida glabrata, C. tropicalis and Candida parapsilosis. Antifungal susceptibility testing revealed no resistance in C. albicans, to the commonly used antifungal agents, whereas resistance or dose dependent susceptibility to fluconazole was observed in some of the NCAC species.Conclusion:Oral carriage of opportunistic pathogenic yeasts was greater in HIV-seropositive persons heading towards immunocompromised state, as evidenced by their CD4+ cell count. The predominant yeast isolated in this study (C. albicans), was found to be susceptible to commonly used antifungals.

Response to therapy in patients with cryptococcosis and AIDS: Association with in vitro susceptibility to fluconazole

BackgroundThe implications of the Cryptococcus neoformans resistance to fluconazole on patient therapy have not been fully elucidated due to the discordant results found in published studies. AimsTo establish the influence of C. neoformans resistance to fluconazole in the therapy of individuals with cryptococcosis and AIDS. MethodsThis study retrospectively compared the clinical course of patients with cryptococcosis according to the level of fluconazole resistance of their C. neoformans isolates. ResultsThis study included 71 episodes of cryptococcosis, defined as those isolates of C. neoformans obtained from patients with mycosis, of which 36 isolates were sensitive to fluconazole, 20 susceptible dose-dependent (SDD), and 15 were resistant. There were 5 treatment failures in the consolidation phase; two occurred in patients who had a susceptible strain, 2 in patients who had SDD strains, and one in a patient who had a resistant strain. During the maintenance treatment, relapses occurred in 4 of 33 patients (12%), seen during the follow-up period, none of which occurred in the group with resistant isolates. There were no significant differences in survival time free of treatment failure (p=0.65) or survival time free of failure or relapse (p=0.38). These results were not affected when tested in a Cox model that included age, CD4T lymphocyte counts, and use of antiretroviral therapy. ConclusionsIn HIV patients with cryptococcosis, the resistance of C. neoformans appeared not to increase the risk of failure or relapse during treatment.

Nasopharyngeal carriage of Streptococcus pneumoniae in Romanian children before the introduction of the pneumococcal conjugated vaccination into the national immunization programme: a national, multi-centre, cross-sectional observational study

We analysed the distribution of vaccine and non-vaccine Streptococcus pneumoniae serotypes and the antimicrobial susceptibility of pneumococcal strains isolated from healthy Romanian children. A multi-centre cross-sectional study was performed in four counties to evaluate carried strains of S. pneumoniae isolated from 2000 children aged 0-5 years. S. pneumoniae carriage was detected in 25.25% of the tested children. Carriage increased from 16.7% among infants to 29.4% in 3-5-year-old children (p<0.0001). The proportions of the serotypes included in pneumococcal conjugate vaccines PCV7, PCV10, and PCV13 among our isolates were 39.9%, 40.1%, and 58.7%, respectively. Erythromycin resistance was 72.5%, and it was significantly lower in non-vaccine serotypes compared with PCV13 serotypes: 57.3% versus 83.6% (p<10(-7)). Penicillin minimum inhibitory concentrations (MICs) >0.064mg/l were recorded in 71.6%, but the penicillin MIC was >2mg/l for only 8.4% of tested isolates. In Romanian children, the majority of carried S. pneumoniae isolates are vaccine serotypes. The isolates with MICs defining macrolide resistance were very frequent, as well as the isolates with MICs defining penicillin resistance in the case of meningitis or penicillin dose-dependent susceptibility for other infections, mainly for the strains belonging to PCV13 serotypes. The implementation of PCV13 within the Romanian national immunization programme could reduce the circulation of these strains with higher macrolide and/or penicillin MICs.

Genetic and phenotypic characterization of Candida albicans strains isolated from infectious disease patients in Shanghai.

Candida albicans, as an opportunistic pathogen, can cause superficial and life-threatening candidiasis in immunocompromised individuals. The formation of surface-associated biofilms and the appearance of drug resistance pose a significant challenge for clinical intervention. In this study, a total of 104 hospital-acquired C. alibcans clinical isolates were collected from sterile sites and mucosal lesions of 92 infectious disease patients in the Shanghai Public Health Clinical Center and analysed. The resistance rates to fluconazole, itraconazole and voriconazole were 12.5 %, 15.4 % and 11.5 % respectively. Multilocus sequence typing (MLST) analysis identified 63 diploid sequence types (DSTs) with a decentralized phylogeny, of which 37 DSTs (58.7 %) had not been reported in the online MLST database. Loss of heterozygosity was observed in ACC1 and ADP1 sequences obtained from six sequential isolates from a patient receiving antifungal treatment, which exemplified the effect of microevolution on C. albicans genetic alterations. Biofilm formation capability, an important virulence trait of C. albicans, was variable among strains isolated from different anatomical sites (P = 0.0302) and affected by genotypes (P = 0.0185). The mRNA levels of the azole antifungal target ERG11 gene and efflux pump genes (CDR1, CDR2 and MDR1) were detected in 9-18.1 % of azole-resistant and susceptible-dose dependent (S-DD) isolates. Twelve mutations encoding distinct amino acid substitutions in ERG11 were found in azole-resistant and S-DD isolates. Among them, A114S, Y132H and Y257H substitution in the ERG11 gene may be primarily related to azole resistance. Taken together, we observed a high level of diversity within C. albicans isolates. Multiple inter-related underlying mechanisms, including genetic and environmental factors, may account for high surface adhesion or azole resistance in clinical C. albicans infections.

Characterization of azole resistance mechanisms in Chilean clinical isolates of Candida albicans

The commensal yeast Candida albicans, can cause superficial or systemic candidiasis in susceptible hosts. In Chile, azole antifungals are the most widely used drugs in the treatment of candidiasis. In a previous study performed at our center, 2.1 and 1.6% of clinical isolates of C. albicans were found to be resistant to fluconazole and voriconazole, respectively. To characterize the resistance mechanisms involved in azoles resistance in Chilean clinical isolates. Eight resistant, nine susceptible-dose dependent (SDD) and 10 susceptible strains (n: 27) were selected according to the Clinical Laboratory Standards Institute (CLSI) M27-S3 criteria, from vaginal and urine samples. Mutations in the 408-488 region of the ERG11 gene were studied by sequencing, and the relative expression of ERG11 gene and efflux pump genes CDR1, CDR2 and MDR1, was evaluated by quantitative real-time PCR (q-PCR). No mutations were detected in the ERG11 gene and its overexpression was found only in 12.5% of the resistant strains (1/8). The most prevalent mechanism of resistance was the over-expression of efflux pumps (62.5%; 5/8). The study of the expression of efflux pumps by q-PCR could be a useful diagnostic tool for early detection of azole resistance in C. albicans.

Polyvinylpyrrolidone oral films of enrofloxacin: film characterization and drug release.

Enrofloxacin is a fluoroquinolone derivative used for treating urinary tract, respiratory and skin infections in animals. However, low solubility and low bioavailability prevented it from using on humans. Polyvinylpyrrolidone (PVP) is an inert, non toxic polymer with excellent hydrophilic properties, besides it can enhance bioavailability by forming drug polymer conjugates. With the aim of increasing solubility and bioavailability, enrofloxacin thin films were prepared using PVP as a polymer matrix. The obtained oral thin films exhibited excellent uniformity and mechanical properties. Swelling properties of the oral thin films revealed that the water uptake was enhanced by 21%. The surface pH has been found to be 6.8±0.1 indicating that these films will not cause any irritation to oral mucosa. FTIR data of the oral thin films indicated physical interaction between drug and polymer. SEM analysis revealed uniform distribution of drug in polymer matrix. In vitro drug release profiles showed enhanced release profiles (which are also pH dependant) for thin films compared to pure drug. Antibacterial activity was found to be dose dependent and maximum susceptibility was found on Klebsiella pneumonia making this preparation more suitable for respiratory infections.

Antifungal susceptibilities of Candida isolates causing bloodstream infections at a medical center in Taiwan, 2009-2010.

We used the Sensititre YeastOne (SYO) method (Trek Diagnostic Systems) to determine the MICs of nine antifungal agents against 474 nonduplicate blood Candida isolates. The MIC results were interpreted according to updated clinical breakpoints (CBPs) recommended by the Clinical and Laboratory Standards Institute (CLSI; document M27-S4) or epidemiology cutoff values (ECVs). The rates of fluconazole susceptibility were 99.2% (234/236) in Candida albicans, 86.7% (85/98) in C. tropicalis, and 97.7% (42/43) in C. parapsilosis. Among the 77 isolates of C. glabrata, 90.9% showed dose-dependent susceptibility (S-DD) to fluconazole. Nearly all isolates of C. albicans, C. parapsilosis, and C. krusei were susceptible to voriconazole; however, rates of voriconazole susceptibility were 78.6% in C. tropicalis. Few isolates of C. albicans (n = 5; 2.1%) and C. glabrata (n = 3; 3.9%), no isolates of C. parapsilosis, C. krusei, and C. guilliermondii, but 62.2% (n = 51) of C. tropicalis isolates were non-wild type for posaconazole susceptibility. For itraconazole susceptibility, 98.3% of C. albicans isolates were wild type, and 3.9% (n = 3) of C. glabrata isolates were non-wild type. Almost all of the isolates tested (>97% for all species) were susceptible to both micafungin and anidulafungin. All isolates tested were found to be wild type for amphotericin B susceptibility, with MICs of <1 μg/ml. Further evaluation is needed to establish CBPs of antifungal agents by the 24-h SYO method for the management of patients with candidemia or other invasive candida infections.