[Susceptibility of drug-resistant staphylococci isolated from different parts of the ocular anterior segment to common ophthalmic antibiotics]

Objectie To investigate the susceptibility of drug-resistant staphylococci isolated from different parts of the anterior segment to levofloxacin, tobramycin, cefazolin sodium, fusidic acid and clindamycin. Methods: Experimental Study. A total of 67 patients with anterior segment infection (33 cases of conjunctivitis, 6 cases of bacterial keratitis, 7 cases of blepharitis, 9 cases of neonatal dacryocystitis, 9 cases of neonatal dacryocystitis, 1 case of adult dacryocystitis and 11 cases of other infectious eye diseases) were collected from the conjunctival sac, cornea, eyelid margin and lacrimal sac. Minimum inhibitory concentration (MIC) determination of methicillin-resistant Staphylococcus (MRS) strains and β-lactamase-producing (β-Lac) strains by a micro-liquid-based method, according to the M100 standard of the American Institute for Clinical and Laboratory Standardization Susceptibility and resistance determinations were made. Data were statistically analyzed using Chi-square or Fisher's exact test. Results: Thirty-five MRS, 30 β-Lac and 2 β-Lac MRS isolates were identified from 67 multidrug-resistant Staphylococcus . There were 3, 9, 4, and 19 MRS isolates isolated from the lacrimal sac, cornea, eyelid margin and conjunctival sac, accounting for 3/4, 9/12, 4/8, 19/43 (44.2%) of the isolated sites respectively. There were 1, 3, 3, and 23 β-Lac isolates, accounting for 1/4, 3/12, 3/8 and 23/43 (53.5%) of the isolated sites, respectively. The highest proportion of β-Lac isolates isolated from patients with a diagnosis of conjunctivitis was 17 (25.3%) from the conjunctival sac. Among the MRS strains isolated from the cornea and lacrimal sac, 5 (7.5%) and 3 (4.5%) were from patients diagnosed with bacterial keratitis and neonatal tear, respectively. The number of MRS strains and β-Lac isolates isolated from patients with a diagnosis of blepharitis were both 3 (4.5%) from the lid margin.Among the strains isolated from the eyelid margin and the conjunctival sac, drug-resistant Staphylococcus epidermidis was the main strain, the drug-resistant Staphylococcus aureus was the major isolates in lacrimal sac and cornea. Among the 35 MRS isoaltes, 25, 24, 12, 12, and 11 were sensitive to cefazolin sodium, fusidic acid, levofloxacin, clindamycin and tobramycin, and the sensitivity rates were 71.4%, 68.6%, 34.3%, 34.3% and 31.4%, the difference was statistically significant (χ²=22.756, P<0.001), The sensitivity rates of levofloxacin, tobramycin, cefazolin sodium, fusidic acid and clindamycin against MRS isolates from the anterior segment were both statistically significant differences (χ²=18.493, 11.594, 8.906, 9.841, 16.059; all P<0.05). The susceptibility rates of MRS isolates against five antibiotics was statistically significant differences (χ²=33.080, P<0.001). Among the 30 β-Lac isolates, 27, 22, 19, 16, and 8 were sensitive to cefazolin sodium, fusidic acid, levofloxacin, tobramycin and clindamycin, and the sensitivity rates were 90.0 % , 73.3%, 63.3%, 53.3% and 26.7%, the difference was statistically significant (χ²=28.280, P<0.001). The sensitivity rates of five antibiotics against β-Lac isolates from the anterior segment were both statistically significant differences (χ²=50.971, 24.543, 48.147, 44.899, 18.676; all P<0.001). The susceptibility rates of β-Lac isolates against five antibiotics was statistically significant differences (χ²=23.383, P<0.001). The sensitivity of cefazolin sodium and fusidic acid against β-Lac isolates were higher than MRS isolates. Conclusions: Cefazolin sodium and fusidic acid may be the best choice for the treatment of drug-resistant Staphylococcus isolated from anterior conjunctival sac, cornea, eyelid margin and lacrimal sac, especially for β-Lac-producing drug-resistant Staphylococcus infection.

[Analysis of the diagnostic efficiency of combining multiple laboratory hematological indicators in alpha-fetoprotein-negative hepatocellular carcinoma]

Objective: To establish a diagnostic model for alpha-fetoprotein-negative hepatocellular carcinoma (AFP-NHCC) by combining multiple laboratory hematological indicators and explore its clinical diagnostic efficiency. Methods: A total of 124 inpatients, including 110 males and 14 females, aged 57 (51, 66) years, who were first diagnosed with AFP-NHCC in the PLA General Hospital were included from December 2011 to June 2017. Meanwhile, 331 cases of non-HCC were enrolled as the control group, including 279 males and 52 females, aged 58 (51, 63) years old, with 47 cases of hepatitis B virus (HBV) infection, 40 cases of liver cirrhosis, 64 cases of hepatic hemangioma or cysts, 7 cases of liver nodules, 8 cases of fatty liver, 146 cases of non-liver disease and 19 health controls. Subjects in the AFP-NHCC group and the control group were divided into a training group and a validation group. A total of 196 subjects were involved in the training group, including 103 AFP-NHCC patients and 93 non-HCC patients (19 healthy controls, 25 patients with HBV infection, 22 patients with liver cirrhosis, 23 patients with hepatic hemangioma or cyst, and 4 patients with liver nodules). The differences in laboratory parameters were analyzed, and a diagnostic model of AFP-NHCC under different AFP levels was established. Likewise, 259 subjects, including 113 patients with liver disease, were involved in the validation group to verify the diagnostic efficiency of the model for AFP-NHCC. The receiver operating characteristic (ROC) curve was used to analyze the sensitivity and specificity of different models, and the area under the curve (AUC) was calculated to evaluate the diagnostic performance of different models. Results: In the training group, the indicators of AFP-NHCC diagnostic model included platelet (PLT), prothrombin activity (PTA), serum albumin (ALB), prothrombin time (PT) and carbohydrate antigen 19-9 (CA19-9), and the AUC of the model was 0.848 (95%CI: 0.786-0.911) when AFP≤5 μg/L. Similarly, the indicators of AFP-NHCC diagnostic model included PLT, PTA, ALB, PT and hematocrit (HCT), and the AUC of the model was 0.839 (95%CI: 0.780-0.897) when AFP≤10 μg/L. When AFP≤20 μg/L, the indicators of AFP-NHCC diagnostic model contained PLT, PTA, ALB, PT, HCT and AFP, and the AUC of the model was 0.866 (95%CI: 0.815-0.917). The AUC values of these three models were higher than those of AFP and CA19-9 alone for the diagnosis of AFP-NHCC [0.634 (95%CI: 0.560-0.709), 0.691 (95%CI:0.620-0.761), all P<0.05]. The indicators screened by these three models were combined to establish the final diagnostic model, and the AUC of the model was 0.873 (95%CI: 0.824-0.923), with the sensitivity of 78.6% (81/103) and the specificity of 81.7% (76/93). In the validation group, the predictive AUC of the final model in liver disease patients was 0.892 (95%CI: 0.832-0.951), with the sensitivity of 100% (21/21) and the specificity of 71.7% (66/92), while in the total validation population, the predictive AUC was 0.931 (95%CI: 0.890-0.972), with the sensitivity of 100.0% (21/21) and the specificity of 75.6% (180/238). Conclusion: The final diagnostic model includes PLT, PTA, ALB, PT, HCT, CA19-9 and AFP, which has higher sensitivity and specificity, and has good diagnostic efficiency for the clinical diagnosis of AFP-NHCC.

[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 β-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).

First Report in China on the Identification and Drug Sensitivity of Mycobacterium elephantis Isolated from the Milk of a Cow with Mastitis

OBJECTIVE

In this study, milk from a cow with mastitis was analyzed to determine the presence of mycobacterial infection. Milk quality and security problems pertaining to the safe consumption of dairy products were also discussed in this study.

METHODS

Milk was preprocessed with 4% NaOH. Then, mycobacteria were isolated from the milk sample on L-J medium. The isolate was identified using multiple loci Polymerase Chain Reaction (PCR) and multi-locus sequence analysis with 16S rRNA, sodA, hsp65, and ITS genes. The drug sensitivity of the isolate to 27 antibiotics was tested through alamar blue assay.

RESULTS

Smooth, moist, pale yellow colonies appeared on the L-J medium within a week after inoculation. Based on the results of multiple loci PCR analysis, the isolate was preliminarily identified as non-tuberculous mycobacteria. The 16S rRNA, SodA, hsp65, and ITS gene sequences of the isolate exhibited 99%, 99%, 99%, and 100% similarities, respectively, with those of the published reference strains of Mycobacterium elephantis (M. elephantis). The drug sensitivity results showed that the strain is resistant to isoniazid, p-aminosalicylic acid, and trimesulf but is sensitive to ofloxacin, rifampicin, amikacin, capreomycin, moxifloxacin, kanamycin, levofloxacin, cycloserine, ethambutol, streptomycin, tobramycin, rifabutin, ciprofloxacin, linezolid, cefoxitin, clarithromycin, and minocycline.

CONCLUSION

To the best of our knowledge, this study is initially to report the isolation of M. elephantis from the milk of a cow with mastitis in China.

[A preliminary study on the molecular characteristics of D-cycloserine resistance of Mycobacterium tuberculosis]

Objective: To investigate the relationship between D-cycloserine resistance and the gene mutations of alrA, ddlA and cycA of Mycobacterium (M.) tuberculosis, as well as the association between D-cycloserine resistance and spoligotyping genotyping. Methods: A total of 145 M. tuberculosis strains were selected from the strain bank. D-cycloserine resistant phenotypes of the strains were determined by the proportion method and the minimal inhibitory concentration was determined by resazurin microtiter assay. PCR amplification and DNA direct sequencing methods were used for the analysis of gene mutations. Relationship between the resistance phenotype and genotype was analyzed by chi-square test. Results: Of the 145 clinically collected strains, 24 (16.6%) of them were D-cycloserine resistant and 121 (83.4%) were sensitive. There were only synonymous mutations noticed on alrA, ddlA and cycA in sensitive strains. Of the 24 D-cycloserine resistant strains, 3 (12.5%) isolates' cycA and 1 (4.2%) isolates' alrA happened to be non-synonymous mutations, in which the codes were 188, 318 and 508 of cycA, and 261 of alrA, respectively. Results on drug sensitivity tests confirmed the minimal inhibitory concentration of the mutant strains were all increased to some degrees. The D-cycloserine resistant rates of 88 Beijing genotype and 57 non-Beijing genotype strains were 20.5% and 10.5% , respectively, but with no statistically significant difference (χ(2) =2.47, P>0.05). Conclusions: The non-synonymous mutations of alrA and cycA might contribute to one of the mechanisms of M. tuberculosis D-cycloserine resistance. M. tuberculosis Beijing genotype or non-Beijing genotype was not considered to be associated with the D-cycloserine resistance.