ObjectiveTo analyze the characteristics of distribution and drug resistance of clinical isolated staphylococci in the Whire Union Bacterial Resistance Surveillance Network across Sichuan from 2015 to 2018, so as to provide reference for clinical rational drug use and management of drug-resistant bacteria in Sichuan.MethodsA total of 18 023 strains of staphylococci were isolated from 9 hospitals of Whire Union Bacterial Resistance Surveillance Network for four years (2015-2018). Drug susceptibility test was carried out by disk diffusion method or automated instrument method. The data were statistically analyzed by WHONET 5.6 according to CLSI 2016 standard.ResultsThe 18 023 strains of staphylococci included 10 865 (60.28%) Staphylococcus aureus and 7 158 (39.72%) coagulase negative staphylococci. No strains resistant to vancomycin and linezolid were found. The detection rates of methicillin-resistant Staphylococcus aureus and methicillin-resistant coagulase-negative staphylococci were 25.10% (2 727/ 10 865) and 75.60% (5 411/7 158), respectively. The sensitivity of methicillin-resistant staphylococci to most antibiotics was significantly lower than that of methicillin-sensitive strains (P<0.05). The susceptibility rate of staphylococci to some antibiotics was significantly different from 2015 to 2018(P<0.05). The susceptibility rates of Staphylococcus aureus from different samples to rifampicin, moxifloxacin, ciprofloxacin, levofloxacin, oxacillin and erythromycin were significantly different (P<0.05). The susceptibility rates of Staphylococcus aureus from different departments in different samples of sulfamethoxazole, rifampicin, moxifloxacin, ciprofloxacin, levofloxacin, oxacillin, gentamicin, tetracycline, clindamycin and erythromycin were significantly different (P<0.05).ConclusionsThe susceptibility of strains isolated from different periods, different specimens and departments to the same antimicrobial agents varies greatly. For the infection of staphylococci, we should use drugs under the guidance of drug susceptibility according to the source of samples, which can avoid the abuse of beta-lactam drugs. Strengthening the monitoring and control of drug-resistant bacteria can prevent or reduce the spread of drug-resistant bacteria.
Objective To investigate the incidence rate, molecular epidemiology and risk factors for methicillin-resistant Staphylococcus aureus (MRSA) infection. Methods A total of 119 Staphylococcus aureus strains isolated from January 2016 to December 2020 in general surgery of this hospital were collected retrospectively and divided into MRSA group and methicillin-sensitive Staphylococcus aureus group according to whether or not resistant to oxacillin. The clinical data of all patients infected with Staphylococcus aureus and drug sensitivity of Staphylococcus aureus were collected. Molecular typing was performed by multilocus sequence typing (MLST), resistance gene, virulence gene and biofilm gene were detected by polymerase chain reaction (PCR) method, and a case-control study was used to identify risk factors for MRSA infection. ResultsThe detection rate of MRSA was 57.98% (69/119), mainly was from pus specimens (80.67%, 96/119). The results of MLST showed that the dominant clone types were ST88 (37.68%, 26/69), ST951 (27.54%, 19/69) and ST59 (18.84%, 13/69). The results of PCR showed that the detection rates of mecA, mecC, Aac (6′ )/Aph (2′ ′ ), Aph (3)-Ⅲ, ant (4′ )- Ⅰ a, tetM, qnrA, panton-valentine leukocidin, fibronectin-binding protein A, staphylococcal enterotoxin A, staphylococcal enterotoxin B, α-hemolysins, intracellular adhesion A, staphylococcal accessory regulators A, and fibronectin-binding protein B in 69 strains of MRSA were 100%, 0.00%, 27.54%, 34.78%, 18.84%, 14.49%, 1.45%, 8.70%, 98.55%, 11.59%, 91.30%, 94.20%, 92.75%, 97.10% and 86.96%, respectively. Multivariate analysis showed that hospital transfer, wound infection, catheter related infection, drainage tube and history of cephalosporin using were risk factors for MRSA infection. ConclusionsThe detection rate of MRSA in general surgery of this hospital is high. ST88 is the most common clone type. The carrying rates of resistant-, virulence- and biofilm-related genes are high. Hospital transfer, wound infection, drainage tube, history of cephalosporin using etc. are high risk factors for MRSA infection. It is advised that invasive operation should be reduced, antibiotics should be used rationally, hand hygiene should be paid attention to, environmental sanitation disinfection should be carried out regularly, and the monitoring of MRSA bacteria should be strengthened, so as to reduce and control the infection and spread of MRSA.
Objective To validate the advantage of repairing bone defect by staphylococcus aureus injection carried in collagen membrane. Methods Twentyfour adult New Zealand rabbits were divided into two groups randomly. After the experimental model of standard bone defect had been made by operation, collagen membrane/staphylococcus aureus injection and staphylococcus aureus injection with the same quantity were transplanted in bone defect areas of the two groups respectively. The reconstructed tissues were observed by general method, X-ray, histology, and immunohistochemistry at 2nd、4th、6th、8th week respectively. Results The experimental group showed that new bone proliferated distinctly in bone defect areaand the proliferation lasted long, and no excessive connective tissue in defectarea. X-ray observation showed that there was continual callus growth in transplantation area in early stage and the distribution of new bones was even in the group. Histological observation showed that there were many new bone growth centers in bone defect area, trabecular bones were sequentially distributed, and mature bone replacement was complete. Immunohistochemical examination showed that bone morphogenetic protein (BMP) could be seen for a long time and BMP took up a large part in the new bone tissues. Conclusion Collagen membrane could prevent parenchyma from penetrating into bone defect area and provide room for new bone growth. As the carrier of staphylococcus, collagen membrane could reduce the overflow of staphylococcus and improve its curative effect as well.
ObjectiveTo investigate the appropriate concentration of methicillin-resistant Staphylococcus aureus (MRSA) in establishing chronic femoral osteomyelitis model in rabbits.MethodsForty-eight adult New Zealand white rabbits were randomly divided into 6 groups with 8 rabbits in each group. Animals in groups B, C, D, E, and F were injected 1×109, 1×108, 1×107, 1×106, 1×105 CFU/mL MRSA on the location of 2 cm of the femoral supracondyle, respectively, and group A was injected with aseptic saline as a control. The general observation were performed at 4 weeks after operation, and the wound secretions were taken for bacteriological examination. The serum C-reactive protein content was detected at preoperation and 2 weeks and 4 weeks after operation. The X-ray, CT scan, and Norden imaging scoring were performed at 4 weeks after operation. At 4 weeks after operation, the animals were sacrificed, and the specimens were observed and evaluated by general scores; and the HE staining and histological score were also performed.ResultsFive rabbits died of severe infection in group B, 2 died in group C, and no rabbit died in groups D, E, and F. General observation showed that the incision healed without soft tissue swelling in group A; most animals had visible incision swelling and sinus formation, femoral thickening, bone destruction, and damage decreased with the decreasing of the concentration of liquid bacterial in groups B-D; the infection signs were seen in groups E and F, and the degree of infection were less than that of group D. Bacteriological examination showed that fistula formation animal in groups B, C, D, and E were cultured with positive results, and with the decrease of concentration, the number of animal fistula formation decreased gradually; and bacteriological culture did not be performed in group F because of no sinus formation. There was no significant difference in the content of C-reactive protein between groups before operation (P>0.05). The contents of C-reactive protein in groups B-F were significantly higher than those in group A at 2 and 4 weeks after operation (P<0.05). At 4 weeks after operation, the content of C-reactive protein was in the order of groups B, C, D, E, F, and A in turn from high to low, showing significant differences between groups (P<0.05). Imaging examination showed that there was no soft tissue swelling and bone destruction in group A; bone destruction, massive sequestrum formation, and soft tissue swelling were found in groups B and C; bone destruction was observed in groups D and E, and the degree of sequestrum formation was not as good as that in group C; and there was a small amount of bone infection in group F. The Norden scores in groups B-F were significantly higher than that in group A, and in groups B and C than those in groups D, E, and F, and in groups D and E than that in group F (P<0.05); there was no significant difference between groups B and C, and between groups D and E (P>0.05). The specimens general observation scores in groups B-F were significantly higher than that in group A, while in groups B and C than those in groups D, E, and F (P<0.05); there was no significant difference between groups D, E, and F (P>0.05). HE staining showed that the structure of bone trabecula in group A was clear and the structure was arranged neatly; in groups B-F, trabecular bone destruction and inflammatory cell infiltration were seen and the degree gradually decreased. The histological scores in groups B-F were significantly higher than that in group A, and in group B than those in groups C-F, in groups C and D than that in group F (P<0.05); there was no significant difference between groups C, D, and E, and between groups E and F (P>0.05).ConclusionThe optimal MRSA concentration of rabbit model of chronic osteomyelitis of femur is between 1×106 and 1×107 CFU/mL.
ObjectiveTo analyze the pathogenic bacteria distribution, structure and characteristics of drug resistance in patients with acute stroke complicated with pulmonary infection, in order to provide reference for the prevention of hospital infection and rational use of antimicrobial agents.
MethodsA total of 864 clinical specimens of acute stroke complicated with pulmonary infection were chosen for study between January 2012 and December 2014. Separation and cultivation were done in accordance with the operation procedures regulated by the Ministry of Health. Drug sensitivity examination was done by Kirby-Bauer (k-b). Super-extensive spectrum β lactamase (ESBL) and methicillin resistant staphylococcus aureus (MRSA) were detected to analyze the bacterial species and resistance transition.
ResultsA total of 864 samples were cultivated, in which G-bacteria accounted for 61.2%. The main pathogenic bacteria was Klebsiella pneumoniae bacteria, Escherichia coli, Pseudomonas aeruginosa, Acinetobacter baumanmii and Staphylococcus aureus. Imipenem had high antimicrobial activity to G-bacilli, especially to Escherichia coli and Klebsiella pneumoniae bacteria. Linezolid, vancomycin and teicoplanin had high antibacterial activity to staphylococcus aureus. Vancomycin resistant Staphylococcus aureus was not found. Ciprofloxacin had high antibacterial activity to Pseudomonas aeruginosa, while imipenem had low antibacterial activity to Pseudomonas aeruginosa. Amikacin had high antibacterial activity to acinetobacter.
ConclusionG-bacilli are predominant in acute stroke complicated with pulmonary infection. ESBLs and MRSA detection rate is high, and we should pay attention to the rational use of antibiotics to reduce drug resistance.
Objective To investigate the effect of aureolysin （Aur） on staphylococcus aureus biofilm formation of dacron biomaterial surfaces under different Aur concentration. Methods Ninety dacron biomaterials were divided into 3 groups （group A, group IA, control group） with random number table （30 piece in each group）. Dacron biomaterials were put into vials contained staphylococcus aureus （105 CFU/ml） respectively; then Aur was added to make the concentration at 400ng/ml in group A, and group B at 80ng/ml. The thickness and number of staphylococcus aureus biofilm on the surfaces of dacron biomaterials of each group were evaluated by confocal laser microscopy and scanning electron microscopy after incubating 6h, 16h, 24h, 30h, and 48h. Results The thickness and number of staphylococcus aureus biofilm on dacron biomaterials surfaces increased significantly with time dependence in control group. The thickness and number of staphylococcus aureus biofilm in group A were less than those in group B and control group at each time points （P〈0. 05）. The thickness and number in group B were significantly decreased than those in control group （P 〈 0. 05）. Conclusion The study shows that Aur can effectively inhibit the formation of staphylococcus aureus biofilm on dacron biomaterials surfaces with dose dependence.
Objective To establish rabbit models of mixture-infectious endophthalmitis induced by exogenous Staphylococcus aureus (S. aureus) and Escherichia coli (E. coli). Methods A total of 84 eyes of 42 New Zealand white albino rabbits were randomly divided into 4 groups. There were 21 eyes in each group. Rabbit eyes in group 1, 2, 3 and 4 received an intravitreal injection of 0.1 ml of mix bacterium (2times;104 CFU/ ml, including 103 S. aureus and 103 E. coli), S. aureus (104 CFU/ ml), E. coli (104 CFU/ml), and sterilized saline respectively. The eyes were examined by slit-lamp microscopy, ophthalmoscopy, A/B scan, electroretinography (ERG) and bacterial culture of vitreous humors at the timepoints of 6, 12, 24, 48 and 72 hours, and 4, 7, 10, 14 days after intravitreal injection. All eyeballs were then enucleated for histopathological examination. Results Various degrees of inflammatory reactions were presented in the 3 experimental groups after the injection, and the development trend of the disease was nearly the same. In group 1 active intraocular inflammation like anterior chamber exudates, started at 12 hours after injection (which was early than that in group 2 and 3), aggravated between 48 and 72 hours, alleviated slowly from 4 to 7 days, and was obviously better after 10 to 14 days while the corneal neovascularization and vitreous gray opacity begun to form. The bacterial culture was positive in group 1 (100％, 6 hours to 14 days after injection), group 2 (100%, 6 hours to 3 days after injection) and group 3 (100% from 6 hours to 7 days, and 67.67% at 14 days after injection). It was negative for group 2 (7 to 14 days after injection) and group 4 (6 hours to 14 days after injection). The amplitude of ERG b wave dissapeard in group 1 to 3, and decreased less than 30% in group 4 from the 48th hour after injection. Histopathological examination revealed that all intraocular structures infiltrated with inflammatory cells. Conclusion Complicated endophthalmitis rabbit models can be successfully established by intravitreal injection with S. aureus and E. coli.
ObjectiveTo summarize the clinical features and experience of Methicillin-resistant Staphylococcus aureus (MRSA)-associated enteritis.
MethodsClinical data of 21 patients with MRSA-associated enteritis who were treated in our hospital from Jan. 2003 to May. 2015 were analyzed retrospectively.
ResultsAfter diagnosed or suspected of MRSA-associated enteritis, the 21 patients received a drug therapy with vancomycin instead of other antibiotic, 3 patients (14.3%) who failed to get satisfactory symptom relief received a plus therapy with biapenem; 13 patients (61.9%) received treatment which plus drugs such as Bacillus licheniformis capsules or combining Bifidobacterium to regulate intestinal microflora. Severe complications, such as intestinal fistula (8 patients, 38.1%）, toxic shock (16 patients, 76.2%）, organ system failure (14 patients, 66.7%) occurred in 17 patients (80.9%) of the 21 patients when 2-7 days (mean of 4.7 days) after diarrhea. Among 21 patients received therapy, 7 patients (33.3%) were cured and 2 patients (9.5%) were improved, whereas 11 patients died, with a total mortality of 52.4%, another 1 patient was lost to follow up (4.8%). There were 8 patients who were followed-up for 1-12 months (the median time was 3.1-month). During the followed-up period, 2 of them died and others stayed alive without occurrence.
ConclusionAlthough uncommon, MRSA-associated enteritis progressed rapidly, with many complications and high mortality rate. Early diagnosis and timely targeted treatment restoring the balance of gastrointestinal microecology are the key to decrease its mortality.
Objective To investigate the genetic polymorphism of methicillin resistant Staphylococcus aureus ( MRSA) isolated from hospital acquired pneumonia. Methods Seventy-four hospitalized patients were diagnosed as noscomial MRSA pneumonia from January 2007 to January 2008 in Xinhua Hospital, Shanghai Jiaotong Univesity. The genes of MRSA were amplified by random amplified polymorphic DNA typing ( RAPD) assay in 82 clinical isolates from these patients. Results Two to 15 amplified DNA fragments were observed in agarose gel and they were classified into 11 genotypes. Genotypes Ⅲ, Ⅵ and Ⅶ ( 32. 56% , 30. 23% and 13. 95% , respectively) were mainly isolated from the ICU. Both independent genotypes and overlapping genotpyes with those from ICU were identified in isolates from the departments of geriatrics, emergency and respiratory medicine. Outbreak or cluster cases ( 48. 65% ) were found in 36 of the 74 patients while all outbreak cases occurred in the ICU. Conclusions Noscomial MRSA pneumonia is easy to disseminate and small-scale outbreak may occur especially in ICU. RAPD is valuable for identification and prevention of the spread of MRSA in hospital.
Methicillin-resistant Staphylococcus aureus is one of the important pathogens of healthcare-associated infections. In order to prevent and control the transmission of the drug-resistant organism in healthcare facilities, the Healthcare Infection Society and the Infection Prevention Society jointly conducted the guidelines for the prevention and control of methicillin-resistant Staphylococcus aureus in 2021. This article introduces the guide from the background, preparation process, main prevention and control measures and further studies, and compares the guidelines with the current prevention and control measures in China, so as to provide a methodological reference for preparation of the guide for domestic infection prevention and control practitioners, and provide evidence-based prevention and control strategies for clinical practice.
