Candidemia in Adult Patients in the ICU: A Reappraisal of Susceptibility Testing and Antifungal Therapy.

OBJECTIVE: To provide updates on the epidemiology and recommendations for management of candidemia in patients with critical illness. DATA SOURCES: A literature search using the PubMed database (inception to March 2023) was conducted using the search terms "invasive candidiasis," "candidemia," "critically ill," "azoles," "echinocandin," "antifungal agents," "rapid diagnostics," "antifungal susceptibility testing," "therapeutic drug monitoring," "antifungal dosing," "persistent candidemia," and "Candida biofilm." STUDY SELECTION/DATA EXTRACTION: Clinical data were limited to those published in the English language. Ongoing trials were identified through ClinicalTrials.gov. DATA SYNTHESIS: A total of 109 articles were reviewed including 25 pharmacokinetic/pharmacodynamic studies and 30 studies including patient data, 13 of which were randomized controlled clinical trials. The remaining 54 articles included fungal surveillance data, in vitro studies, review articles, and survey data. The current 2016 Infectious Diseases Society of America (IDSA) Clinical Practice Guideline for the Management of Candidiasis provides recommendations for selecting empiric and definitive antifungal therapies for candidemia, but data are limited regarding optimized dosing strategies in critically ill patients with dynamic pharmacokinetic changes or persistent candidemia complicated. RELEVANCE TO PATIENT CARE AND CLINICAL PRACTICE: Outcomes due to candidemia remain poor despite improved diagnostic platforms, antifungal susceptibility testing, and antifungal therapy selection for candidemia in critically ill patients. Earlier detection and identification of the species causing candidemia combined with recognition of patient-specific factors leading to dosing discrepancies are crucial to improving outcomes in critically ill patients with candidemia. CONCLUSIONS: Treatment of candidemia in critically ill patients must account for the incidence of non-albicans Candida species and trends in antifungal resistance as well as overcome the complex pathophysiologic changes to avoid suboptimal antifungal exposure.

Anti-Candida activity and in vitro toxicity screening of antifungals complexed with ß-cyclodextrin.

The emergence of resistant fungal species and the toxicity of currently available antifungal drugs are relevant issues that require special consideration. Cyclodextrins inclusion complexes could optimize the antimicrobial activity of such drugs and create a controlled release system with few side effects. This study aimed to assess the in vitro toxicity and antifungal effectiveness of nystatin (Nys) and chlorhexidine (Chx) complexed or not with ß-cyclodextrin (ßCD). First, a drug toxicity screening was performed through the Artemia salina bioassay. Then, the minimum inhibitory concentrations (MICs) against Candida albicans were determined with the broth microdilution test. After MICs determination, the cytotoxicity of the drugs was evaluated through the methyl-thiazolyl-tetrazolium (MTT) and neutral red (NR) assays and through cell morphology analysis. The PROBIT analysis was used to determine the median lethal concentration (LC50), and the cell viability values were submitted to one-way analysis of variance(ANOVA)/Tukey (α = 0.05). Overall, the ßCD-complexed antifungals were less toxic against A. salina than their raw forms, suggesting that inclusion complexes can reduce the toxicity of drugs. The MICs obtained were as follows: Nys 0.5 mg/L; Nys:ßCD 4 mg/L; Chx 4 mg/L; and Chx:ßCD 8 mg/L. Chx showed significant cytotoxicity (MTT: 12.9 ± 9.6%; NR: 10.6 ± 12.5%) and promoted important morphological changes. Cells exposed to the other drugs showed viability above 70% with no cellular damage. These results suggest that antifungals complexed with ßCD might be a biocompatible option for the treatment of Candida-related infections.

The effect of TiO2 nanoparticles on bacterial growth: the effect of particle size and their structure - a systematic review.

One of the widely used microbiological methods to determine the toxicity of chemicals, catalysts, and other types of materials is the minimum inhibitory concentration (MIC) test. The present study aims to investigate the influence of composition of composite materials based on TiO2 and their particle size as well as bacterial type and shape based on the MIC values reported in the literature. The results show that among the 36 articles selected, most of the studies used Escherichia coli (E. coli) (26) and Staphylococcus aureus (S. aureus) (19) bacteria to determine MIC values. This study revealed that the MIC in values below 70 µg ml-1 for S. aureus was lower than that for E. coli bacteria (below 200 µg ml-1). Importantly, MIC value decreased from 60.6 to 7.66 µg ml-1 with decrease in the size of nanoparticles. It follows from the increased surface area for smaller-sized particles, thus increased interaction with bacteria during MIC test.

High levels of antimicrobial resistance in Escherichia coli and Salmonella from poultry in Ecuador.

Objective: To describe antimicrobial resistance profiles of Escherichia coli and Salmonella spp. isolated from chicken carcasses and the antimicrobials commonly used in animals in Ecuador and provide information on antimicrobial resistance patterns for implementing evidence-based corrective measures. Methods: Meat samples were collected from chicken carcasses in 199 slaughterhouses across Ecuador as part of a national pilot study for monitoring antimicrobial resistance in agricultural sources in 2019. Samples were tested for E. coli and Salmonella spp. Sensitivity to 10 critically important and three highly important antimicrobials (from a human health perspective) was assessed. The country report submitted to the World Organization for Animal Health was accessed to extract the quantity of antimicrobials produced or imported for use in animals. Results: Of 383 samples, E. coli was isolated from 148 (39%) and Salmonella spp. from 20 (5%) samples. Ninety percent of the isolates were resistant to at least one critically important antimicrobial. Resistance was highest to erythromycin (E. coli 76%; Salmonella spp. 85%) and tetracycline (E. coli 71%; Salmonella spp. 90%). Critically or highly important antimicrobials (colistin, tetracycline, trimethoprim/sulfamethoxazole) formed the bulk (87%) of antimicrobials used in animals as per the World Organization for Animal Health report. Conclusions: High prevalence of antimicrobial resistance in poultry in Ecuador calls for the development of guidelines and regulations on the use of antimicrobials and for engagement with livestock producers. The existing surveillance system needs to be strengthened to improve the monitoring of antimicrobial use and evolving resistance patterns.

Antibacterial Effects of X-ray and MRI Contrast Media: An In Vitro Pilot Study.

Some radiological contrast agents have been shown to have effects on bacterial growth. In this study, the antibacterial effect and mechanism of action of iodinated X-ray contrast agents (Ultravist 370, Iopamiro 300, Telebrix Gastro 300 and Visipaque) and complexed lanthanide MRI contrast solutions (MultiHance and Dotarem) were tested against six different microorganisms. Bacteria with high and low concentrations were exposed to media containing different contrast media for various lengths of time and at pH 7.0 and 5.5. The antibacterial effect of the media was examined in further tests using agar disk diffusion analysis and the microdilution inhibition method. Bactericidal effects were found for microorganisms at low concentrations and low pH. Reductions were confirmed for Staphylococcus aureus and Escherichia coli.

[Comparison of Epsilometer test and agar dilution method in detecting the sensitivity of Helicobacter pylori to metronidazole].

OBJECTIVE: Agar dilution method (ADM) was used as the golden standard to evaluate the consistency of Epsilometer test (E-test) in detecting the sensitivity of Helicobacter pylori (H. pylori) to metronidazole. METHODS: From August 2018 to July 2020, patients with H. pylori infection treated for the first time in Peking University Third Hospital for gastroscopy due to dyspepsia were included in this study. Gastric mucosas were taken from the patients with H. pylori infection. H. pylori culture was performed. Both the ADM and E-test were applied to the antibiotic susceptibility of H. pylori to metro-nidazole, and the consistency and correlation between the two methods were validated. RESULTS: In the study, 105 clinical isolates of H. pylori were successfully cultured, and the minimum inhibitory concentration ≥ 8 mg/L was defined as drug resistance. Both ADM and the E-test showed high resistance rates to metronidazole, 64.8% and 62.9%, respectively. Among them, 66 drug-resistant strains were detected by ADM and E-test, and 37 were sensitive strains, so the consistency rate was 98.1%. Two strains were evaluated as drug resistance by ADM, but sensitive by the E-test, with a very major error rate of 1.9%. There was zero strain sensitive according to ADM but assessed as resistant by the E-test, so the major error rate was 0%. Taking ADM as the gold standard, the sensitivity of E-test in the detection of metronidazole susceptibility was 97.1% (95%CI: 0.888-0.995), and the specificity was 100% (95%CI: 0.883-1.000). Cohen's kappa analysis showed substantial agreement, and kappa coefficient was 0.959 (95%CI: 0.902-1.016, P < 0.001). Spearmans correlation analysis confirmed this correlation was significant (r=0.807, P < 0.001). The consistency evaluation of Bland-Altman method indicated that it was good, and there was no measured value outside the consistency interval. In this study, cost analysis, including materials and labor, showed a 32.2% higher cost per analyte for ADM as compared with the E-test (356.6 yuan vs. 269.8 yuan). CONCLUSION: The susceptibility test of H. pylori to metronidazole by E-test presents better agreement with ADM. Because it is less expensive, less labor intensive, and more rapid, it is an easy and reliable method for H. pylori susceptibility testing.

Applications of Lab on a Chip in Antimicrobial Susceptibility of Staphylococcus aureus: A Systematic Review.

Background and Objectives: Staphylococcus aureus is a prevalent bacterium capable of inducing various infections, including skin and soft tissue infections, bloodstream infections, pneumonia, and surgical site infections. The emergence of antimicrobial resistance in S. aureus, particularly methicillin-resistant S. aureus, has raised substantial concerns within global healthcare settings. Prior to antibiotic prescription, the ideal approach is antimicrobial susceptibility testing (AST); however, this is frequently perceived as excessively complex and time-intensive. Lab-on-a-chip (LOC) technology holds promise in addressing these challenges and advancing fundamental microbiological research while also aiding in the development of therapeutic strategies. This systematic review aims to evaluate the potential utility of LOC for AST of S. aureus. Materials and Methods: This study adhered to the PRISMA guidelines. Various databases, including SCOPUS, PubMed/MEDLINE, SCIELO, and LILACS, in addition to gray literature sources, were employed in the review process. Results: Sixteen studies were included in this systematic review. All these studies detailed the effectiveness, rapidity, and predictability of LOC systems for assessing S. aureus susceptibility to various antibiotics. When comparing the LOC approach to traditional manual methods, it was evident that LOC requires a minimal quantity of reagents. Furthermore, most studies reported that the entire LOC procedure took 10 min to 7 h, with results being equally accurate as those obtained through traditional AST protocols. Conclusions: The potential application of LOC for AST of S. aureus is emphasized by its ability to provide rapid access to minimum inhibitory concentration data, which can substantially aid in selecting the most suitable antibiotics and dosages for treating challenging infections caused by this microorganism. Moreover, the rapid AST facilitated by LOC holds promise for enhancing the appropriateness and efficacy of therapy in clinical settings.

Clinical characteristics, antimicrobial resistance, and risk factors for mortality in paediatric invasive pneumococcal disease in Beijing, 2012-2017.

BACKGROUND: To analyse clinical characteristics, antibiotic susceptibility, and risk factors for mortality in paediatric invasive pneumococcal disease (IPD) in Beijing. METHODS: Paediatric IPD patients in our hospital were retrospectively collected from 2012 to 2017. Clinical manifestations, laboratory tests, antimicrobial susceptibility and serotype of isolates, and risk factors for mortality of IPD were analysed. RESULTS: Overall, 186 IPD cases were enrolled. The major manifestations were meningitis (76), pneumonia with bacteraemia (60), bacteraemia without focus (21), and pneumonia with empyaema (22). Of 72 cases with underlying diseases, leukaemia (18.0%), congenital heart disease (15.3%), primary immunodeficiency disease (12.5%), nephrotic syndrome (12.5%), and cerebrospinal fluid leakage (12.5%) were most common. In total 96.9% of isolates would have been covered by the pneumococcal conjugate vaccine (PCV13), including 19F (32.8%), 19A (23.4%), 4 (17.2%), and 23F (9.4%). Nonsusceptibility rates of penicillin, cefotaxime, and cefepime among nonmeningitis patients increased between 2012 and 2017; The mortality rate was 21.5%. Meningitis, respiratory failure, multiple organ failure, and white blood cell count < 4000 cells/µL were independent risk factors for mortality. CONCLUSION: Meningitis was the most common clinical manifestation of IPD, and was frequently associated with death. Strains in the PCV13 vaccine would cover most of the cases, and so wider use of PCV13 should be considered.

Ambient NO2 is associated with Streptococcus pneumoniae-induced pneumonia in children and increases the minimum inhibitory concentration of penicillin.

The present study aimed to assess the correlation between ambient air pollutants and Streptococcus pneumoniae (S. pneumoniae)-induced pneumonia in children and retrospectively reviewed the daily data regarding S. pneumoniae from children with pneumonia in a tertiary hospital of Hangzhou City, between January 1st, 2018, and December 31st, 2018. The excess risk (ER) of NO2 with regard to the daily number of S. pneumoniae isolates obtained from the respiratory tract specimens of children with pneumonia was 13.31% (95% confidence interval [CI]: 3.12-24.51%, P = 0.010) in the single-pollutant model. An increase of 10 µg/m3 in NO2 exposure was associated with a 23.30% increased risk for the acquisition of S. pneumoniae-induced pneumonia in children (95% CI: 2.02-49.02%; P = 0.031) according to the multi-pollutant model. The ER of NO2 with regard to the daily number of S. pneumoniae isolates (1 µg/ml ≤ minimum inhibitory concentration (MIC) to penicillin ≤ 2 µg/ml) obtained from the respiratory tract specimens of children with pneumonia was 15.80% (95% CI: 2.02-31.45%; P = 0.024) in the single-pollutant model. According to the multi-pollutant model, the ER of NO2 with regard to the daily number of S. pneumoniae isolates (1 µg/ml ≤ MIC to penicillin ≤ 2 µg/ml) obtained from the respiratory tract specimens of children with pneumonia was 37.09% (95% CI: 5.70-77.81%; P = 0.018). In conclusion, ambient NO2 is associated with S. pneumoniae-induced pneumonia in children. More importantly, NO2 exposure is associated with the increased MICs of penicillin against S. pneumoniae from children with pneumonia.

From Etest to Vitek 2: Impact of Enterococcal Linezolid Susceptibility Testing Methodology on Time to Active Therapy.

Different linezolid antimicrobial susceptibility testing (AST) methodologies yield various results. In 2018, we transitioned our linezolid AST methodology from the Etest to Vitek 2. We sought to evaluate the impact of this change on antibiotic use among 181 inpatients with vancomycin-resistant enterococcal (VRE) infections. The transition from Etest to Vitek 2 resulted in an increase in linezolid susceptibility (38% versus 96%; P < 0.001) and a reduction in time to active antibiotic therapy (3 versus 2.6 days; P = 0.007).

Systematic Review of Whole-Genome Sequencing Data To Predict Phenotypic Drug Resistance and Susceptibility in Swedish Mycobacterium tuberculosis Isolates, 2016 to 2018.

In this retrospective study, whole-genome sequencing (WGS) data generated on an Ion Torrent platform was used to predict phenotypic drug resistance profiles for first- and second-line drugs among Swedish clinical Mycobacterium tuberculosis isolates from 2016 to 2018. The accuracy was ∼99% for all first-line drugs and 100% for four second-line drugs. Our analysis supports the introduction of WGS into routine diagnostics, which might, at least in Sweden, replace phenotypic drug susceptibility testing in the future.

Antibacterial activity of salvia officinalis L. against periodontopathogens: An in vitro study.

Being aware of the remarkable antimicrobial potential of S. officinalis L., we aimed to evaluate the antimicrobial activity of the S. officinalis dichloromethane crude extract (SOD), dichloromethane-soluble fractions (SODH and SODD), SODD subfractions (SODD1 and SODD2), and pure substances (manool, salvigenin, and viridiflorol) against periodontopathogens. This bioassay-guided study comprises five antimicrobial tests-determination of the Minimum Inhibitory Concentration (MIC), determination of the Minimum Bactericidal Concentration (MBC), determination of the antibiofilm activity, construction of the Time-kill curve (determination of Bactericidal Kinetics), and determination of the Fractional Inhibitory Concentration Index-on six clinical bacterial isolates and three standard bacterial strains involved in periodontal disease. SOD has moderate activity against most of the tested bacteria, whereas SODD1, SODH1, SODH3, and manool afford the lowest results. The Porphyromonas gingivalis (ATTC and clinical isolate) biofilm is considerably resistant to all the samples. In association with chlorhexidine gluconate, only SODH1 exerts additive action against P. gingivalis (clinical isolate). Therefore, SODH1 and manool are promising antibacterial agents and may provide therapeutic solutions for periodontal infections.

[Pathogenicity and drug-resistance analysis of Candida glabrata in patients with oral candidiasis].

Objective: To investigate the detection rate, population features and in vitro antifungal drug susceptibility of Candida glabrata in patients with oral candidiasis. Methods: The saliva fungi culture cases and the ratio of Candida glabrata in patients with oral candidiasis were analyzed during 2014-2018. Fungal species were identified by CHROMagar Candida chromogenic medium and API 20C AUX yeast identification kit. Sixty strains with cfu≥200/ml were collected and performed the in vitro antifungal susceptibility tests by using ATB FUNGUS 3 susceptibility kit. Results: The number of patients with oral candidiasis was 12 401 and the ratio of Candida glabrata was 3.44% (427/12 401) from 2014 to 2018. The positive ratio of infection increased with age increasing.The positive rate of female aged 41 to 50 years old began to increased. Female aged more than 50 years old subgroups demonstrated the tendency towards increased positive rates with increasing age. It was found out through clinical data analyzing that the patients with oral candidiasis were the most and oral lichen planus, Sjögren's syndrome and xerostomia carrying high quantity ratios of infection. Candida glabrata had highest resistance(8.3%) to the fluconazole, 6.7% of the isolates were of non-WT phenotype to itraconazole and voriconazole, all of the isolates were of WT phenotype to amphotericin B. Conclusions: The ratio of infection in the patients with oral candidiasis increased with age increasing and the olders are susceptible to infection. Candida glabrata has a certain resistance to azoles and clinically reasonable use of antifungal drugs according to the results of drug susceptibility is very important.

[Comparison study on sensitivity of five ophthalmic antibiotics to common drug-resistant Staphylococci on ocular surface].

Objective: To investigate the in vitro antibacterial sensitivity of levofloxacin, tobramycin, cefazolin sodium, clindamycin and fusidic acid to 67 strains of Staphylococci in ocular surface infection. The purpose of this study is to provide reference for clinical selection of drugs. Methods: Experimental study. Sixth-seven strains of drug-resistant Staphylococci isolated from the Department of Microbiology, Henan Provincial Ophthalmic Hospital during January 2018 and May 2019 were collected. There were 67 strains of Staphylococci including 28 strains of drug-resistant Staphylococcus epidermidi, 17 strains of drug-resistant Staphylococcus aureus, 15 strains of drug-resistant Staphylococcus intermedius and a few other kinds of drug-resistant Staphylococci. The minimum inhibitory concentrations (minimum inhibitory concentration, MIC) of levofloxacin, tobramycin, cefazolin sodium, clindamycin and fusidic acid in 67 strains of drug-resistant Staphylococci were determined by microliquid-based method. The sensitivity was determined according to the American CLSI-M100 standard. The statistical analysis of the data was carried out by using two-dimensional test and Fisher accurate test. Results: Fourteen strains of fusidic acid were sensitive to 17 strains of MRS-Meca-resistant Staphylococcus epidermidis, the difference between fusidic and levofloxacin is statistically significant; 14 strains of cefazolin sodium and 11 strains of fusidic acid were sensitive to 14 strains of ß-Lac enzyme-producing Staphylococcus aureus, and there were significant differences between the two drugs and levofloxacin; 6 strains of cefazolin sodium and 5 strains of fusidic acid were sensitive to 10 strains of MRS-Meca-resistant Staphylococcus intermedius, as compared to levofloxacin, there were significant differences between cefazolin sodium and levofloxacin (P=0.011,0.033). Cefazolin sodium was sensitive to 5 strains of MRS-Meca-positive other drug-resistant Staphylococci, which was significantly different from levofloxacin (P=0.048); 54 and 48 strains of cefazolin sodium and fusidic acid were sensitive to 67 strains of drug-resistant Staphylococci, and the sensitive rates were 80.1% and 71.6%, respectively, which were significantly higher than those of levofloxacin, tobramycin and clindamycin. There were significant statistical differences between drug sensitivity (χ²=18.377,9.940；P=0.000,0.003). Conclusions: The sensitivity of cefazolin sodium and fusidic acid to 67 strains of drug-resistant Staphylococci is better than that of levofloxacin, tobramycin and clindamycin, these findings may provide guidance for the clinical treatment of drug-resistant Staphylococci in ocular infection. (Chin J Ophthalmol, 2020, 56: 621-625).

[A study of bacterial distribution and drug resistance in skin and soft tissue infection].

Objective: To investigate pathogenic bacteria and drug resistance in the patients with skin and soft tissue infection in order to provide the scientific evidences for clinical reasonable use of antibiotics. Methods: A retrospective analysis was performed on patients with skin and soft tissue infections in Department of Dermatology, Peking University Third Hospital from January 2012 to December 2017. Pus, secretions, skin lesions, urine, throat swabs, and alveolar lavage fluid were collected for bacterial culture, bacterial species were identified by VITEK2 Compact system and BD-Bruker MALDI Biotyper system. Drug resistance was detected by K-B agar diffusion method recommended by CLSI. Results: A total of 392 strains of bacteria were isolated from 327 patients distributed in 21 genus and 56 species, of which 225 were gram-positive cocci (57.40%), 114 were gram-negative rods (29.08%), 46 were gram-positive rods (11.73%), and 7 were gram-negative cocci (1.79%). The top 3 bacteria were Staphylococcus aureus 91(23.21%), Staphylococcus epidermidis 42 (10.71%), and Pseudomonas aeruginosa 24 (6.12%). Staphylococcus had a high rate of resistance to penicillin and erythromycin (>50%). Gram-negative rods were resistant to ampicillin (86.1%), and also had certain resistance to most second-generation and some third-generation cephalosporin (about 50%). There was no significant change in the drug resistance rate of MRSA compared to MSSA. Only the resistance rate to tetracycline was statistically different (P<0.05). Conclusion: The emergence of drug-resistant strains is an important factor leading to refractory infections. There are a wide range of pathogenic bacteria species among the skin and soft tissue infection patients, and antimicrobial drugs should be chosen wisely according to drug sensitivity.

A Guide to Bacterial Culture Identification And Results Interpretation.

PURPOSE: To provide a guide to interpreting bacterial culture results. METHODS: Studies were identified via a PubMed literature search (from 1966 to January 2018). Search terms included microbial sensitivity tests, microbial drug resistance, and anti-infective agents/pharmacology. Articles were included if they were published in English. References within identified articles were also reviewed. RESULTS: This paper reviewed core concepts of interpreting bacterial culture results, including timing of cultures, common culture sites, potential for contamination, interpreting the Gram stain, role of rapid diagnostic tests, conventional antibiotic susceptibility testing, and automated testing. CONCLUSION: This guide can assist pharmacists in their role as integral members of the antimicrobial stewardship team in an effort to improve patient care.

Antimicrobial Drug Resistance in Blood Culture Isolates at a Tertiary Hospital, Uganda.

We summarize antimicrobial drug resistance (AMR) patterns from blood cultures at a tertiary hospital in Uganda. High rates of resistance to first-line antibiotic drugs were observed among Staphylococcus aureus and gram-negative organisms. Microbiology services with susceptibility testing should be strengthened to support standardized reporting of AMR data in sub-Saharan Africa.

[Etiological and drug sensitivity analysis of lacrimal canaliculitis].

Objective: To analyze the etiology and drug sensitivity of lacrimal canaliculitis. Methods: Retrospective study of case series. The general information, culture results and drug sensitivity results of 52 patients (including 10 males and 42 females with an average age of 60.3 years) clinically diagnosed with lacrimal canaliculitis during 2011 and 2016 at Beijing Tongren Hospital of Capital Medical University have been analyzed. The enumeration data have been tested with Chi-square method. Results: The positive rate of bacterial culture was 78.8%, and the fungal culture tests of all cases showed negative results. Sixty strains of bacteria were isolated from 41 patients whose bacterial culture tests showed positive results, Gram-positive bacteria have been confirmed as the main among the isolated bacteria with Streptococcus (18.3%), Propionibacterium (18.3%), and Streptococcus (15.0%) identified as the three common genera. Thirteen cases (25.0%, all the 13 patients were female) involved with mixed infection, 13.3% (8/60) of the isolated strains were multi-drug resistant bacteria. The drug sensitive rate of the bacteria to fluoroquinolones antibiotics(79.3%, 230/290) was higher than that to cephalosporins(62.1%, 36/58) and aminoglycoside antibiotics(56.3%, 98/174), and such differences are of statistical significance (χ(2)=7.977, 27.738, P<0.05). Except for the fact that gram-positive bacteria are mostly sensitive to vancomycin, the sensitive rate of the bacteria to gatifloxacin was the highest and that to tobramycin was the lowest. Conclusion: Lacrimal canaliculitis tend to affect women and elderly patients. Staphylococcus, Propionibacterium, and Streptococcus are the three most common genera. Gatifloxacin may be the preferred antibiotic. Antibiotics combination therapy should be applied for multi-drug resistant bacteria. (Chin J Ophthalmol, 2018, 54: 111-114).

[Genetic typing and susceptibility testing of strains from Staphylococcus aureus keratitis or conjunctivitis patients].

Objective: To study the relationship between genetic typing and the antibiotic susceptibility of staphylococcus aureus (SA) isolated from keratitis or conjunctivitis patients. Methods: Experimental study. Thirty-four (34) strains of Staphylococcus aureus were isolated from 34 cases of keratitis or conjunctivitis. The genomic DNA was extracted and amplified with PCR. With the method of multi locus sequences typing (MLST), gene fragments from 7 house-keeping genes were amplified and the products were sequenced. The results were submitted to the MLST website (www.pubmlst.org). In comparison with the allele of the corresponding gene, the allele spectrums of the strain were obtained with 7 housekeeping genes. At last, the MLST genotypes of the isolated strains were determined. With the START software, the evolutionary tree was established with UPGMA method. With the microdilution method, the MIC(90) of 13 antimicrobial agents was determined. The MIC(90) value of antimicrobial agents among different genotypes of Staphylococcus aureus was comparatively analyzed. Results: Ten (10) genotypes were obtained from 34 strains of Staphylococcus aureus. The dominant types were ST239, ST2592 and ST188. The clustering of genotyping was relatively concentrated, mainly in group Ⅰ (25 strains of SA, 83.3% of the total), and followed by group Ⅱ (5 strains of SA, 16.7%). The conjunctival isolates were distributed in the subgroup A of group Ⅰ. The cornea isolates were concentrated in subgroup B and group Ⅱ. With the exact probability method, the R×C chi square tests were used as statistic analysis method. The difference between the bacterial genotyping of two sources was statistically significant (P=0.011). Twenty-four strains of SA in group Ⅰ was sensitive to Vancomycin, Rifampicin and Amikacin (sensitivity ratio was 24/24, 20/24 and 20/24, respectively), and was generally resistant to other antibiotics. The values of MIC(90) of ciprofloxacin, ofloxacin, gatifloxacin and moxifloxacin to Staphylococcus aureus in subgroup A (0.16±0.07, 0.51±0.42, 0.31±0.14, 0.22±0.33) were significantly lower than the values in subgroup B(0.74±0.11, 0.84±0.45, 0.67±0.03, 0.68±0.26). The difference was statistically significant (P=0.004, 0.026, 0.034, 0.001). There was no significant difference between the MIC(90) values of the other 9 kinds of antibiotics in the subgroup A and in the subgroup B of Staphylococcus aureus (P value 0.047-0.561). Conclusion: The genotype of Staphylococcus aureus of corneal isolations and conjunctival isolations were different. The conjunctival isolates were distributed in the subgroup A of group Ⅰ and the corneal isolates were concentrated in subgroup B and group Ⅱ. There is a significant correlation between the MLST genotypes and antibiotic sensitivity. (Chin J Ophthalmol, 2018, 54:767-774).

COMPARISON OF TWO DIFFERENT METHODS FOR TIGECYCLINE SUSCEPTIBILITY TESTING IN ACINETOBACTER BAUMANNII.

- Tigecycline susceptibility testing (TST) presents a tremendous challenge for clinical microbiologists. Previous studies have shown that the Epsilometer test (E-test) and Vitek 2 automated system significantly overestimate the minimum inhibitory concentrations for tigecycline resistance compared to the broth microdilution method (BMM). This leads to very major errors or false susceptibility (i.e. the isolate is called susceptible when it is actually resistant). The aim of this study was to compare E-test against BMM for TST in carbapenem-resistant and carbapenem-susceptible Acinetobacter (A.) baumannii and to analyze changes in tigecycline susceptibility between two time periods (2009-2012 and 2013-2014), with BMM as the gold standard. Using the EUCAST criteria, the rate of resistance to tigecycline for the OXA-23 MBL-positive, OXA-23 MBL-negative and carbapenemase-negative strains for BMM was 54.5% (6/11), 29.4% (5/17) and 2.7% (1/37), respectively; the OXA-24/40 and OXA-58 producing organisms did not exhibit any resistance. With E-test, all OXA-23 MBL-positive organisms (11/11), 23.5% (4/17) of OXA-23 MBL-negative, and 4.1% of OXA-24/40 (3/74) strains displayed tigecycline resistance; there were no resistant strains among the OXA-58 and carbapenemase-negative isolates. Resistance emerged in the bacterial isolates from 2013 to 2014. Although tigecycline does not display cross-resistance, the highest rates of resistant A. baumannii isolates were observed among those producing VIM MBL, regardless of the testing method. These findings suggest that the commercial E-test does not provide reliable results for TST of A. baumannii. Further confirmation with the dilution method should be recommended, particularly in cases of serious infections.