Colonization with methicillin-resistant Staphylococcus aureus after liver transplantation.

Methicillin-resistant Staphylococcus aureus (MRSA) is a frequent cause of infection after orthotopic liver transplantation (OLT). Colonization with MRSA is associated with a higher risk of infection. Previous studies have shown a high prevalence of MRSA colonization among OLT candidates. However, the risk of colonization with MRSA after OLT is still unclear. The objective of this study was to estimate the incidence and the factors associated with colonization with MRSA after OLT. This was a prospective cohort study including patients submitted to OLT between the years 2000 and 2002. Surveillance cultures of nasal swab specimens were performed within the 1st 72 hours of hospital admission and, subsequently, on weeks 2, 6, 13, and 26. Patients whose baseline cultures revealed nasal carriage of MRSA were excluded. A total of 60 patients were included in the study. The median follow-up was 72 days. A total of 9 patients (15%) became colonized. In multiple logistic regression analyses, the use of a urinary catheter for > or =5 days (P = .006), postoperative bleeding at the surgical site (P = .009), and preoperative use of fluoroquinolones (P = .08) were associated with a higher risk of colonization. Patients without any of these risk factors did not become colonized. In conclusion, nasal carriage of MRSA is frequently acquired after OLT. Periodic postoperative screening for MRSA carriage should be an integral component in programs designed to reduce nosocomial MRSA transmission in these patients. Further studies are needed to set up and validate a predictive model that could allow targeting postoperative screening to high-risk OLT recipients.     

甲氧西林耐药金黄色葡萄球菌基因分型及耐药现状研究

目的 研究烧伤病房分离的甲氧西林耐药金黄色葡萄球菌(MRSA)的葡萄球菌盒式染色体mec(SCCmec)基因分型及耐药现状. 方法 2012年9月-2013年9月,从笔者单位烧伤整形科ICU及普通病房送检的患者创面分泌物、血液及痰液标本r中,检出非重复金黄色葡萄球菌179株(ICU来源68株、普通病房来源111株).采月头孢西丁K-B纸片扩散法检测金黄色葡萄球菌MRSA表型,对ICU和普通病房中MRSA检出率进行比较.采用PCR法对MRSA进行SCCmec.分型,经检测甲氧西林耐药决定子mecA基因对前述MRSA鉴定结果进行验证 . 采用用 K-B纸片扩散法检测MRSA与甲氧西林敏感金黄色葡萄球菌(MSSA)对23种临床常用抗菌药物的耐药情况 除去MRSA对其耐药率为100.0％或0的抗菌药物,将SCCmecⅢ型MRSA与非SCCmecⅢ型MRSA 对剩余抗菌药物的耐药率进行比较对数据行Pearsonx2检验或校正x2检验. 结果 179株金黄色葡萄球菌中148株鉴定为MRSA占82.7％,其中ICU来源62株、普通病房来源86株;其余31株为MSSA占 17.3％.ICU中 MRSA在该病区内检出金黄色葡萄球菌中所占百分比为91.2％(62/68),显著高于普通病房中的77.5％(86/111),x2=5.526,P=0.019. PCR检测显示148株MRSA均携带mecA基因,其中106株为SCCmecⅢ型阳性占71.6％;ICU与普通病房中 SCCmecⅢ型MRSA占各自病区内检出MRSA的百分比分别为72.6％ (45/62)和70.9％ (61/86),差异无统计学意义(x2=0.048,P=0.826).148株MRSA对青霉素及头孢类抗生素共8种抗菌药物100.0％耐药,对万古霉素、替考拉宁、利奈唑胺、替加环素、呋喃妥因及奎奴普丁/达隔普汀的耐药率均为0除2种菌对其耐药率为0的6种抗菌药物外,MRSA对剩余17种抗菌药物的耐药率均显著高于MSSA(x2值为4.091 ～138.546,P＜0.05或P＜0.01) 106株SCCmecⅢ型MRSA对左氧氟沙星、环丙沙星、利福平、四环素、红霉素、林可霉素、庆大霉素、克林霉素的耐药率分别为56.6％(60/106)、85.8％ (91/106)、89.6％ (95/106) 、86.8％(92/106)、84.9％ (90/106)、78.3％(83/106)、92.5％ (98/106)、74.5％ (79/106),均显著高于42株非SCCmecⅢ型MRSA的33.3％ (14/42)、61.9％(26/42) 、71.4％ (30/42)、66.7％ (28/42) 、69.0％(29/42)、57.1％(24/42)、71.4％(30/42)、52.4％ (22/42),x2值为4.801 ～11.377,P＜0.05或P＜0.01. 结论 笔者单位烧伤病房的MRSA检出率高且耐药现状十分严峻,流行情况以SCCmec.Ⅲ型为主,未见对糖肽类抗生素耐药情况.     

荆州地区耐甲氧西林金黄色葡萄球菌的流行和耐药特征分析

目的 调查荆州地区社区相关性和医院相关性耐甲氧西林金黄色葡萄球菌(CA-MRSA和HA-MRSA)的流行和耐药特征.方法 连续收集2012年1月至2013年12月分离自荆州市中心医院门诊和住院患者送检样本的MRSA 159株.检测16种抗菌药物对所有菌株的最小抑菌浓度,采用多重PCR检测所有菌株的SCCmec分子型别,并分别以脉冲场凝胶电泳(PFGE)和耐药谱聚类分析对ICU的MRSA进行同源性分析.采用WHONET 5.6和SPSS 19.0软件对相关数据进行统计分析.结果 159株MRSA中,HA-MRSA 131株(82.4％),CA-MRSA 28株(17.6％).HA-MRSA和CA-MRSA在患者年龄、病区分布、来源样本类型、住院时间、抗感染治疗时间、感染类型和基础疾病的构成上差异有统计学意义(x2=19.103,31.372,59.756,71.703,54.153,59.756和54.232,P＜0.01).159株MRSA中未检出对万古霉素、利奈唑胺、替加环素和呋喃妥因耐药的菌株,但所有菌株对青霉素、头孢西丁和苯唑两林均耐药.HA-MRSA对莫西沙星、利福平、左氧氟沙星、环丙沙星和庆大霉素的耐药性高于CA-MRSA(x2=30.179,27.352,28.523,28.523和25.987,P＜0.01),但对红霉素和克林霉素的耐药性低于CA-MRSA(x2=13.106和11.743,P＜0.01).159株MRSA中,SCCmecⅡ型12株(7.5％),Ⅲ型113株(71.1％),Ⅳ型26株(16.4％),未能分型8株,CA-MRSA和HA-MRSA分别以Ⅳ(26/28,92.9％)型和Ⅲ型(113/131,86.3％)为主.ICU病区分离的49株HA-MRSA,经PFGE分型可分为6型,以Al(24株,49.0％)、A2亚型(9株,18.4％)和B型(9株,18.4％)为主;耐药谱聚类分析发现3群相关性很高的HA-MRSA,其对应的PFGE型别显示其分属于A1、A2亚型和B型.结论 荆州地区流行的MRSA以HA-MRSA为主,其与CA-MRSA在患者年龄、病区分布、感染类型以及耐药性等方面均显示出差异.HA-MRSA以SCCmecⅢ型为主,且在ICU病区存在HA-MRSA暴发流行.     

Clinical studies of enteritis caused by methicillin-resistant Staphylococcus aureus.

OBJECTIVE: To study the clinical features of methicillin-resistant Staphylococcus aureus (MRSA) enteritis in our surgical ward. DESIGN: Retrospective study. SETTING: Teaching hospital, Japan. SUBJECTS: 16 men and 1 woman who developed MRSA enteritis from January 1995 to October 1999. MAIN OUTCOME MEASURES: Causes and treatments. RESULTS: The underlying diseases were as follows: gastric cancer (n = 13), colorectal cancer (n = 2), recurrent cancer (n = 1) and bowel obstruction following gastrectomy (n = 1). 16 patients were operated on. Two cases were treated with histamine H2 receptor blockers. The mean age of patients was 65 years (range 50-80). In 13 cases MRSA enteritis developed within 6 days of operation. 10 strains of MRSA were isolated from stools, 8 from gastric juice, and 3 from intra-abdominal exudate. 10 patients were treated with vancomycin given through a nasogastric tube and 2 through a nasogastric tube and by drip intravenous infusion. 15 patients survived and 2 died. CONCLUSIONS: Patients who are given broad-spectrum antibiotics and whose gastric secretion is reduced are at high risk of MRSA enteritis. In the surgical ward, early diagnosis, treatment, and isolation are essential for patients with MRSA enteritis.     

Daptomycin for methicillin-resistant Staphylococcus aureus infections of the spine

BackgroundMethicillin-resistant Staphylococcus aureus (MRSA) infection is increasingly common. Treatment with vancomycin-based therapy is often unsuccessful. Daptomycin is a relatively new lipopeptide antibiotic with potent activity against MRSA.PurposeTo describe the successful management of MRSA infection involving the spine.Study designTwo case reports of MRSA infection, one involving epidural and lumbar subdural abscesses, the other with osteomyelitis and discitis.MethodsTwo cases are described, one with lumbar epidural and subdural abscesses and the other with osteomyelitis and discitis of the spine. Switching from vancomycin to daptomycin plus rifampin-based therapy resulted in patient improvement that allowed discharge from the hospital.ResultsBoth patients recovered fully from their infection.ConclusionsDaptomycin is a safe and effective option for the treatment of MRSA infection involving the spine.     

Positive nasal culture of methicillin-resistant Staphylococcus aureus (MRSA) is a risk factor for surgical site infection in orthopedics

Background Although nasal carriage of MRSA has been identified as one of the risk factors for surgical site infection (SSI) with MRSA, there have been no reports of this in the orthopedics field.Methods This prospective observational cohort study included 2,423 consecutive patients who were admitted to our department over 26 months and who underwent orthopedic surgery. We examined the relationship between pre-existing nasal MRSA and subsequent occurrence of SSI with MRSA.Results 63 patients (2.6%) had a positive nasal MRSA culture. 15 patients (0.6%) developed SSI with MRSA. The occurrence of SSI with MRSA in nasal MRSA carriers was significantly higher than that in non-carriers (4 out of 63 (6.3%) vs. 11 out of 2,360 (0.5%); p < 0.001) (adjusted OR: 11; 95% CI: 3–37; p = 0.001).Interpretation We recommend appropriate treatment of patients who are nasal carriers of MRSA before orthopedic surgery.     

Computerized antibiogram for methicillin-resistant Staphylococcus aureus in chest surgery.

BACKGROUND: An increasing number of cases of postoperative morbidity involving methicillin-resistant Staphylococcus aureus have been reported in thoracic surgery. To prevent its outbreak, cluster analysis using a personal computer was employed. METHODS: A total of 120 patients undergoing operations on the lung and mediastinum were included into this study. Materials were isolates of methicillin-resistant Staphylococcus aureus newly recovered from across the hospital. The cluster analysis used antimicrobial susceptibility in 12 drugs, which were categorically valued to produce Euclidean distance to form clusters of similarity. RESULTS: Six of the 120 patients were found to be positive for the microbe before or after thoracotomy. A total of two patients (1.7%) became symptomatic postoperatively, i.e., one of four preoperatively-positive patients and one of two postoperatively-positive cases. The analysis suggested that preoperative patients shared the strains in the same non-surgical ward. DISCUSSION: A computerized antibiogram does not always strictly type Staphylococcal strains but has advantages in typing with ease and at decreased cost. The current analysis suggested that patient harboring the strains migrated across wards. CONCLUSION: Computerized antibiograms for Staphylococcal strains may assist to prevent an outbreak of their infection in chest surgery.     

Positive nasal culture of methicillin-resistant Staphylococcus aureus (MRSA) is a risk factor for surgical site infection in orthopedics

Background Although nasal carriage of MRSA has been identified as one of the risk factors for surgical site infection (SSI) with MRSA, there have been no reports of this in the orthopedics field.

Methods This prospective observational cohort study included 2,423 consecutive patients who were admitted to our department over 26 months and who underwent orthopedic surgery. We examined the relationship between pre-existing nasal MRSA and subsequent occurrence of SSI with MRSA.

Results 63 patients (2.6%) had a positive nasal MRSA culture. 15 patients (0.6%) developed SSI with MRSA. The occurrence of SSI with MRSA in nasal MRSA carriers was significantly higher than that in non-carriers (4 out of 63 (6.3%) vs. 11 out of 2,360 (0.5%); p < 0.001) (adjusted OR: 11; 95% CI: 3–37; p = 0.001).

Interpretation We recommend appropriate treatment of patients who are nasal carriers of MRSA before orthopedic surgery.     

Active infective endocarditis due to methicillin-resistant Staphylococcus aureus in the acute phase of infectious mononucleosis

A 26-year-old male was treated for acute hepatitis due to Epstein-Barr virus and infectious mononucleosis in our hospital. At 2 weeks after admission, there was relapse with high fever. A blood culture detected methicillin-resistant Staphylococcus aureus. A two-dimensional echocardiogram revealed severe aortic regurgitation and vegetation on the left coronary cusp of the aortic valve. The diagnosis was active infective endocarditis due to methicillin-resistant Staphylococcus aureus in the acute phase of infectious mononucleosis. Following preoperative administration of vancomycin, the aortic valve was replaced with a Carbomedics prosthetic valve. The aortic valve was bicuspid, and the right cusp and non-coronary cusp were conjoined. As the focus of infection was localized to the left coronary cusp, the infected tissue was fully removed with resection of all the cusps. Although fever persisted long after the operation, the blood culture became negative for methicillin-resistant Staphylococcus aureus, and repeated echocardiograms including transesophageal echocardiogram showed no prosthetic valve infection. Vancomycin was administered until the C-reactive protein became negative at 45 days after the operation.     

Carriage of methicillin-resistant Staphylococcus aureus is associated with an increased risk of infection after liver transplantation

Methicillin-resistant Staphylococcus aureus (MRSA) is an important cause of sepsis in patients with cirrhosis and after liver transplantation. The association between nasal carriage of MRSA and sepsis in these patients is unclear. The goal of this study was to investigate the relationship between MRSA carriage before liver transplantation and subsequent sepsis after transplantation. This was a retrospective study of 374 consecutive adults who underwent orthotopic liver transplantation between 1998 and 2001 and for whom full data were available. Of these, 157 had been screened for MRSA as part of a study assessing the prevalence of MRSA infection. All MRSA carriers were treated with nasal mupirocin and chlorhexidine baths. The records of MRSA carriers and noncarriers were analyzed for Child and Model for End-Stage Liver Disease (MELD) score, posttransplantation MRSA, and other infections and mortality. Of the 157 patients who had an MRSA screen, 35 patients were MRSA nasal carriers. These carriers had significantly greater MELD score (mean, 16.2 compared with 13.1; P = .02) and Child scores (mean, 10 versus 9; P = .001) than noncarriers. The incidence of posttransplantation MRSA infection was significantly higher in MRSA carriers (31% versus 9%; P = .002). The incidence of other posttransplantation infection was not significantly different in the two groups. There was no significant difference in survival between the two groups (1-year patient survival, 74% and 82%, respectively). Patients carrying MRSA are predisposed to an increased risk of sepsis after liver transplantation with a trend to increased mortality. Screening for MRSA should be considered in high-risk patients being assessed for liver transplantation. (Liver Transpl 2003;9:754-759.)     

Morbidity and mortality of an endemic pathogen: methicillin-resistant Staphylococcus aureus

Over an 8-year period, two epidemics of methicillin-resistant Staphylococcus aureus (MRSA) occurred in a burn unit. Sources of sepsis were the burn wound and lung. Fourteen percent of the patients colonized with MRSA became bacteremic. The mean postburn day of bacteremia was 19 and the mortality rate was 5 percent. MRSA was introduced to the burn unit when a patient was transferred from another unit, on readmission of a previously infected patient, or heavy burn census when MRSA was epidemic in the hospital. Although the morbidity rate associated with MRSA infections was high, the mortality rate was low. Gram-negative sepsis has continued to be more lethal.     

What's in a name? Is methicillin-resistant Staphylococcus aureus just another S aureus when treated with vancomycin?

Methicillin-resistant Staphylococcus aureus (MRSA) strains, principally resistant to penicillinase-resistant penicillins and aminoglycosides, are increasingly common hospital isolates. We have examined the significance of MRSA colonization and infection in 1100 consecutively admitted, seriously burned patients in whom vancomycin was used to treat all staphylococcal infections. Colonization with S aureus (SA) was identified in 658 patients, in 319 of whom MRSA colonization was identified. Two hundred fifty-three SA infections occurred in 178 patients; of these infections, 58% were pulmonic and 38% were bacteremic. Methicillin-resistant SA infections occurred in 58 of the SA-infected patients. A severity index, based on multiple-regression analysis of mortality as a function of burn size and age in the study population, was used to estimate expected mortality. We demonstrated no measurable increase in mortality attributable to MRSA in this population of burned, SA-infected patients. The results question the clinical and economic value of added control practices, such as closing of units, refusal of transfer or admission, added isolation, treatment of carriers, furlough of colonized staff, and other expensive measures that are specifically directed at prevention of MRSA infections in critical care areas.     

In vitro infectability of prosthetic mesh by methicillin-resistant Staphylococcus aureus

Although mesh use is important for effective herniorrhaphy in adults, prosthetic infections can cause serious morbidity. Bacterial adherence to the mesh is a known precursor to prosthetic infection. We compared the ability of common mesh prosthetics to resist bacterial adherence. The meshes studied included polypropylene (Marlex^®), expanded polytetrafluoroethylene (PTFE) with and without silver chlorhexidine coating (DualMesh Plus^® and Dualmesh^®) composite meshes (Composix E/X^®, Proceed^?, and Parietex Composite^®) and lightweight polypropylene meshes (TiMesh^®, Ultrapro^®, and Vypro^®). Fifteen samples of each mesh type were individually inoculated with a suspension of 10⁸ methicillin-resistant Staphylococcus aureus (MRSA) in tryptic soy broth. After incubation at 37°C for 1 h, the mesh pieces were then removed and serially washed. The colony-forming units (CFU) of MRSA present in the initial inoculum, at the end of the 1-h warm-water bath (broth count), and the pooled washes (wash count), were determined using serial dilutions and spot plating. The bacteria not accounted for in the broth or wash counts were considered adhered to the mesh. Samples of each mesh type were also analyzed using scanning electron microscopy (SEM). Data are presented as the mean percentage adherence with ANOVA and Tukey’s test used to determine significance (P<0.05). The DualMesh Plus^® mesh had no detectable MRSA in the broth or the pooled wash samples. Dualmesh^® had less adherence compared with Marlex^®, Proceed^?, and Vypro^® (P<0.05). Conversely, Vypro^® had a statistically higher adherence (96%, P<0.05) as compared to TiMesh^®, Ultrapro^®, Composix E/X^®, and Parietex Composite^®. SEM confirmed bacterial adherence to all the mesh types except DualMesh Plus^®. The ability of a biomaterial to resist infection has an important clinical significance. DualMesh Plus^®, due to its antimicrobial coating, is the only mesh type of the nine tested that demonstrated a bactericidal property. Standard PTFE (Dualmesh^®) also had less bacterial adherence. Vypro^® demonstrated an increase in bacterial adherence; this was possibly due to the multifilament polyglactin 910 weaved within the prolene component of the mesh.     

Acute rise in methicillin-resistant Staphylococcus aureus infections in a coastal community.

OBJECTIVE: Describe the incidence of head and neck community-acquired methicillin-resistant Staphylococcus aureus (CA-MRSA) infections over a 5-year period at a coastal tertiary medical center. STUDY DESIGN: Retrospective chart review. SUBJECTS AND METHODS: All patients presenting to the otolaryngology service with cultures taken from head and neck infections between 1999 and 2004 were eligible for inclusion. Statistical analysis was used to determine significance of the changing incidence of isolated organisms over the study period. RESULTS: CA-MRSA infections rose from 21% to 64% over the 5-year period. The increasing trend in CA-MRSA infections reached statistical significance from 2003 to 2004. All CA-MRSA isolates were resistant to cefazolin and penicillin, but most were sensitive to clindamycin. CONCLUSIONS: Our data demonstrates a striking increase in the incidence of CA-MRSA. We have tailored our treatment of cutaneous head and neck infections to include empiric treatment for CA-MRSA using clindamycin. Awareness and monitoring of this trend will be important for all practitioners involved in the care of these patients.     

Rapid diagnosis of methicillin-resistant Staphylococcus aureus bacteremia by nested polymerase chain reaction.

OBJECTIVE: The purpose of this study was to establish a rapid and sensitive diagnostic method for methicillin-resistant Staphylococcus aureus (MRSA) bacteremia in postoperative patients. SUMMARY BACKGROUND DATA: As a result of diffusion and abuse of third-generation cephalosporin antibiotics in the 1980s in Japan, an outbreak of MRSA infection has been posed. In the field of surgery, severe postoperative infections with MRSA such as MRSA bacteremia, which may lead to multiple organ failure, have emerged with a high mortality. METHODS: Thirty-five patients with high fever (above 38.5 C) or watery diarrhea or both within 2 weeks after gastrointestinal major surgery and 6 healthy volunteers were examined. Nested polymerase chain reaction was used to detect mecA and toxic shock syndrome toxin-1 (TSST-1) genes in blood specimens. RESULTS: The mecA and TSST-1 genes were not detected in the blood samples of any of the six healthy volunteers. In all 12 samples from which MRSA colonies were isolated by blood culture, mecA and TSST-1 genes were detected. Although it took at least 48 hours to identify MRSA by the blood culture method, the presence of mecA and TSST-1 genes was determined by nested polymerase chain reaction method within only 3 to 4 hours after blood sampling. CONCLUSIONS: This method, as a sensitive and rapid monitoring system for MRS bacteremia, would be clinically beneficial for prevention of cross infection and for early determination of appropriate treatment for infected patients.     

Community-acquired methicillin-resistant Staphylococcus aureus: a cause of musculoskeletal sepsis in children.

Between August 1996 and August 1997, 130 children were admitted to our pediatric orthopaedic unit with Staphylococcus aureus musculoskeletal infection. Twenty-six of the 130 staphylococcal isolates were resistant to methicillin, an incidence of 20%. All but one of the infections, a femoral fixator-pin infection, were community-acquired. Twenty-two of the infections were superficial; however, there were four cases of deep musculoskeletal sepsis due to methicillin-resistant S. aureus. In areas where methicillin-resistant S. aureus is prevalent in the community, methicillin resistance should be considered in any overwhelming staphylococcal infection not responding to conventional antibiotics despite adequate surgical debridement.     

Necrotizing fasciitis caused by Staphylococcus aureus: the emergence of methicillin-resistant strains

Staphylococcus aureus is an uncommon causative agent of monomicrobial necrotizing fasciitis, but we have noted several cases over the years. The patients treated for necrotizing fasciitis between January 1998 and December 2008 in our institution were identified, and their medical records were reviewed. Of 105 necrotizing fasciitis cases during the study period, 18 were caused by monomicrobial S. aureus infection (17%). The median age was 62 years (range, 12-81 years). Among this cohort, 10 patients had coexisting medical conditions or risk factors, including diabetes and hypertension. Lower limbs and upper limbs are the most commonly involved sites. Among the bacterial isolates from these cases, 8 were methicillin-sensitive S. aureus (MSSA) and 10 were methicillin-resistant S. aureus (MRSA). One patient died in the MSSA group, and 5 patients died in the MRSA group. The mortality rate and other clinical characteristics were not significantly different between the 2 groups. However, all MRSA necrotizing fasciitis developed after the year 2000, and it was significantly different from MSSA necrotizing fasciitis that predominantly took place before the year 2000. In conclusion, S. aureus is an important pathogen of monomicrobial necrotizing fasciitis, and MRSA has emerged as the predominant causative agent in recent years. Therefore, MRSA-directed antibiotic therapy should be considered when treating patients suspected with necrotizing fasciitis in endemic areas.     

The importance of detecting methicillin-resistant Staphylococcus aureus in an intensive care setting

In recent years, the fight against nosocomial infections has constituted a major public health challenge. Measures aimed at preventing the spread of multiresistant bacteria (MRB) through carriage combine the more or less systematic detection of carriers and precautions concerning isolation. In the light of published data, elements for the evaluation of a cost-efficiency ratio for measures concerning detection and isolation in intensive care are presented. The high levels of methicillin-resistant Staphylococcus aureus (MRSA) observed in hospitals constitute the principal target. Although isolation precautions appear to be effective, the value of detecting MRSA remains a subject of debate. Such detection has several objectives: the identification of carriers, assistance in the implementation of isolation precautions, the eradication of carriage and the evaluation of strategy. These different objectives are discussed.