Nasal Colonization Prevalence Antimicrobial Susceptibility Profiles And Molecular Characteristics Of Staphylococcus Aureus And MRSA In Diabetes Mellitus Patients From Communities

ObjectiveTo investigate nasal colonization prevalence, antimicrobial susceptibility patterns and molecular characteristics of Staphylococcus aureus and MRSA in diabetes mellitus patients from communities, thus can provide scientific basia for preventing and controlling of Staphylococcus aureus and MRSA infection in patients with diabetes mellitus. MethodsCross-sectional study and probability proportional sampling method were conducted to enroll patients with diabetes mellitus in 11 communities of Foshan Lishui. Persons who were not diabetes mellitus from the same community were selected as control population. Epidemiologic information were obtained by self-designed questionnaires and anterior nares swabs were collected at the same time. Staphylococcus aureus was identified according to microbiologic assays methods and MRSA was detected by Cefoxitin disk diffusion test and mec A gene PCR assay. χ2 test, Fisher exact probability test and logistic regression analysis were used to analyze the risk factors of carriying Staphylococcus aureus and MRSA. Antimicrobial susceptibility to antibiotics of Staphylococcus aureus was tested by K-B disk diffusion. PCR assay was applied to detect virulence genes of PVL and SCCmec typing of MRSA. The molecular typing of Staphylococcus aureus was conducted by multilocus sequencing typing. ResultsPatients demographics: A total of 529 patients with diabetes mellitus and 427 control population were recruited for this study. Among patients with diabetes, 161 were males(30.43%), mean age was 66.13±9.34 years.The average age of control group was 64.39±9.45 years,181 of them were males(42.39%).Prevalence and risk factors: 46 strains of Staphylococcus aureus(8.70%) and 22 strains of MRSA(4.15%) were determined in patients with diabetes. 25 strains of Staphylococcus aureus(5.85%) and 12 strains of MRSA(2.81%) were determined in control group. There was no statistical difference toward the rate of Staphylococcus aureus and MRSA between diabetes mellitus and control group. Males could unlikely to carry Staphylococcus aureus(OR=0.45, 95%CI:0.20-0.99), the diabetes mellitus, whose blood sugar control to normal level were 2.04 times risk to carry Staphylococcus aureus than the subjects whose were not.Antimicrobial susceptibility testing: Staphylococcus aureus had different resistance rates to different antibiotics. The resistant rates of cefoxitin, erythromycin, trimethoprim, moxifloxacin and clindamycin of MRSA were significantly higher than those of MSSA(P<0.05). The resistance rates of other antibiotics between MRSA and MSSA were close. No MSSA strain was resistant to linezolid. The rate of multiple drugs resistance of Staphylococcus aureus was 43.66% and MRSA had higher mult-resistant rate to antibiotics toward MSSA, and the difference was statistical significantly(P=0.014). There was statistical difference toward teicoplanin and erythromycin resistant rate between diabetes mellitus and control population(P<0.05). The multiple drugs resistant rate of SA in patients with diabetes was 52.17%,while the rate in control population was 28.00%.PVL gene screeing: Ten strains of Staphylococcus aureus were carring PVL gene, the carriage rate was 14.08%. Six isolates were MRSA(17.65%, 6/34) and four isolates were MSSA(10.81%, 4/33) and there was no statistical difference between the two groups regarding to PVL carriage rates. Five strains of Staphylococcus aureus were carring PVL gene in each group of diabetes mellitus(10.87%, 5/46) and control population(20.00%, 5/25) and there was no statistical difference between the two groups regarding to PVL carriage rates.SCCmec typing: According to the result of detecting SCCmec typing of 34 MRSA strains, we found that one was SCCmecⅠtype(2.94%), four were SCCmec Ⅱ type(11.76%), five were SCCmec Ⅲ type(14.71%), thirteen were SCCmec Ⅳ type(38.24%), five were SCCmec Ⅴ type(14.71%), six strains were not typable(17.64%). 10 strains of MRSA were classified as HA-MRSA and 18 strains of MRSA were classified as CA-MRSA according to SCCmec typing.MLST: 30 STs were found among the 71 Staphylococcus aureus isolates. The most common ST was ST398(9/71, 12.68%), followed by ST7(8/71, 11.26%), ST59(5/71, 7.04%) and ST 72(5/71, 7.04%). According to the clustering analysis between ST types, 2 clonal complexes(CC45 and CC59), 6 doublets(D5, D7, D72, D88, D398 and D2483) and 10 singletons(ST1, ST6, ST9, ST10, ST25, ST30, ST188, ST944, ST946 and ST1937) were found. By e BURST analysis, 11 CCs were identified. CC5 was the most common(28/71, 39.44%), followed by CC398(11/71, 15.49%), CC7(9/71, 12.68%) and CC59(9/71, 12.68%). There was no essential difference between diabetes mellitus and control group in the origin of strains. ConclusionsThere was no difference of nasal colonization prevalence between diabetes mellitus and control group. Females and blood sugar control normally of diabetes mellitus were the independent risk factors for carrying Staphylococcus aureus. The resistance rates of MRSA were higher than that of MSSA commonly and both of them had high multi-drug resistance rate. There were several PVL-positive isolates in Staphylococcus aureus. CA-MRSA was the major type for MRSA, coexisting with HA-MRSA. The STs of Staphylococcus aureus were diverse and were related to international epidemic clones.