High Mortality Related with Staphylococcus aureus Bacteremia After Liver Transplantation

The aim of the present study was to analyze the characteristics of bacteremia occurring in liver-transplant patients in Andalusia, Spain, during the 1990s. At the three participating hospitals, 405 liver transplantations were performed during the study period, and 119 bacteremic episodes were observed following 91 of them (22.4%, 29.4 episodes/100 liver transplants). Gram-positive organisms were the predominant bacteria isolated in cases of early-onset bacteremia (70.7%, P=0.04). The most common sources of bacteremia were the abdomen (33.6%) and intravascular catheters (22.7%), but frequently the source of bacteremia was unknown (31.9%). Mortality at 30 days was 21%. Isolation of Staphylococcus aureus was the only independent risk factor for mortality (relative risk, 3.13; 95% confidence interval, 1.3–7.5; P=0.01). These results indicate that control measures are required in order to reduce the incidence of gram-positive bacteremia and catheter-related infection in this patient population. The observed etiology must be considered when empirical antimicrobial therapy is indicated while awaiting blood-culture results. Electronic Publication     

Methicillin resistant Staphylococcus aureus bacteremia seven years of survey in a French hospital

In our French general hospital with 1000 hospitalization beds, a specific isolation for multiresistant bacteria colonized or infected patients was set up since 1998. To assess the impact of these recommendations, the rate of methicillin-resistant Staphylococcus aureus (MRSA) and methicillin-sensitive Staphylococcus aureus (MSSA) bacteremia was calculated for each year since 1998. From 1998 to 2004, 493 cases of Staphylococcus aureus (SA) bacteremia occurred in our hospital: 319 strains were susceptible to methicillin and 174 were MRSA. During the 7 years period of our study, we observed a significant tendency for reduction in the number of bacteremia with MRSA strains (p=0.016). The significant decrease of the MRSA bacteremia between 1998 and 2004 was obtained through the cooperation between staff members, bacteriologists and hospital nosocomial infection committee members.     

Serratia marcescens bacteremia at a medical center in southern Taiwan: high prevalence of cefotaxime resistance.

Antimicrobial resistance of isolates and risk factors for mortality were retrospectively investigated in 71 adult patients with Serratia marcescens bacteremia. During the 4-year study period, 78 clinically significant episodes of S. marcescens bacteremia occurred in 71 patients. The mean age of the patients was 65 years (range, 25-86 years) with a male predominance (45 patients, 63%). Most of the bacteremic episodes were nosocomial (78%), and 34% were polymicrobial. The overall mortality rate within 2 weeks after the onset of bacteremia was 41%. The presence of malignancy and critical illness at initial presentation were independent risk factors for mortality. By disk susceptibility test, 72 isolates were resistant to cefotaxime (92%) but susceptible to ceftazidime (99%). All isolates were susceptible to meropenem. Among the 47 patients with monomicrobial S. marcescens bacteremia, the mortality rate within 5 days of onset in patients receiving appropriate empirical antimicrobial therapy was lower than that in patients receiving inappropriate therapy although this difference was not significant (14% vs 28%, p = 0.27). Among the patients with cefotaxime-resistant but ceftazidime-susceptible S. marcescens bacteremia treated with ceftazidime, 6 of 7 patients (86%) survived for more than 2 weeks, suggesting the potential effectiveness of ceftazidime in the treatment of cefotaxime-resistant Serratia infections. Further clinical studies are required to delineate the clinical role of ceftazidime therapy for infections caused by S. marcescens with this resistant phenotype.     

Validation and implementation of the GeneXpert MRSA/SA blood culture assay in a pediatric setting

Blood cultures positive for gram-positive cocci in clusters can pose a dilemma for empiric antimicrobial therapy because they could represent coagulase-negative staphylococcus or Staphylococcus aureus bacteremia. The GeneXpert MRSA/SA BC Assay (Cepheid, Sunnyvale, CA) is a polymerase chain reaction-based method for identifying S aureus and methicillin resistance that has been approved for use in adults, but data on its use in samples from pediatric patients is limited. We validated the Xpert MRSA/SA BC Assay for use with anaerobic and polymicrobial specimens from pediatric patients and implemented it for routine presumptive identification of S aureus in our pediatric hospital. The assay was 100% sensitive and specific for methicillin-resistant S aureus and 100% sensitive and 99.5% specific for methicillin-susceptible S aureus. Time to presumptive identification of S aureus bacteremia and determination of methicillin susceptibility was reduced by more than 24 hours. We found the Xpert MRSA/SA BC Assay to be a rapid, accurate tool for detecting methicillin-resistant and methicillin-susceptible S aureus in positive pediatric blood cultures, including polymicrobial cultures and those recovered in anaerobic blood culture media.     

Clinical evaluation of surveillance culture in cancer patients

To clarify usefulness of surveillance culture (SC) as a predictor of infection, we retrospectively studied 70 episodes of bacteremia in 271 cancer patients between April, 1984 and April, 1988. SC was obtained from the throat swabs, stool and urine on admission and then once weekly during hospitalization. Of 76 aerobic strains from blood, 18 (24%) were isolated from SC prior to bacteremia. Seven strains were first identified from SC within 4 days before bacteremia occurred. Of 63 cases of bacteremia, excluding polymicrobial bacteremia, 14 (22%) were initially detected by SC. An antibiotic therapy was altered within 5 days after bacteremia in 19 bacteremic patients with negative SC and 5 with positive SC. Six bacteremic patients with negative SC and 3 with positive SC died within 5 days after the onset of bacteremia. No significant differences were observed in antibiotic therapy (chi 2 test, p less than 0.05) or mortality (p greater than 0.05) between patients who had positive and negative SC. Routine SC is unlikely to influence an initial diagnosis or antimicrobial management for cancer patients with fever.     

Predisposing conditions and pathogens in bacteremia in hospitalized children

Between 1985 and 1995, 1037 bacteremic episodes were recorded in a pediatric tertiary care center and analyzed retrospectively. Gram-positive bacteria accounted for 719 episodes (68%), gram-negative bacteria for 303 (29%), fungi for 16 (2%), and anaerobes for 12 (1%). In 526 (51%) patients, primarily neonates and oncology patients, a predisposing condition was present. In 390 (38%) episodes a clinical source of infection was documented. Mortality was highest inPseudomonas bacteremia (45%). Since the bacterial spectrum differed widely between patient groups, the choice of empirical antimicrobial therapy should be based on any underlying condition present in the patient and the clinical source of infection. As anaerobes were rarely isolated, the routine use of anaerobic blood cultures in patients without predisposing conditions does not seem warranted.     

神经内科重症监护病房医院获得性肺炎 病原菌分布及耐药性分析

目的 探讨神经内科重症监护病房医院获得性肺炎的病原菌分布以及对抗生素的耐药性,为抗感染治疗提供参考。方法 2016年1月~2017年12月入住湖南省第二人民医院神经内科重症监护病房合并院内获得性肺炎的患者79例,采集痰标本进行细菌分离及培养,并对其进行相关药敏试验。结果 共分离出89株病原菌,其中革兰氏阴性菌占87.64%,革兰氏阳性菌10.11%,真菌2.25%。病原菌以鲍曼不动杆菌（24.72%）、肺炎克雷伯菌（19.10%）、铜绿假单胞菌（17.98%）,金黄色葡萄球菌为主（8.99%）为主;鲍曼不动杆菌对大部分抗菌药物耐药,铜绿假单胞菌对头孢哌酮舒巴坦和头孢他啶的耐药率较高,肺炎克雷伯菌耐药率低。金黄色葡萄球菌对青霉素耐药率高。结论 HAP致病菌以革兰氏阴性菌为主,其中鲍曼不动杆菌耐药严重,同时也应注意革兰氏阳性菌和真菌感染。     

Stenotrophomonas maltophilia bacteremia in pediatric patients-- a 10-year analysis.

BACKGROUND AND PURPOSE: Stenotrophomonas maltophilia bacteremia is an important cause of mortality among immunocompromised children. However, there has been little information concerning S. maltophilia bacteremia in the pediatric population. METHODS: We reviewed the drug susceptibility of bloodstream isolates of S. maltophilia and medical charts of S. maltophilia bacteremia patients less than 18 years old at the Department of Pediatrics, National Taiwan University Hospital from January 1993 to June 2003. The risk factors associated with mortality of the patients with S. maltophilia bacteremia were analyzed. RESULTS: In total, 32 episodes (31 patients) of S. maltophilia bacteremia were reviewed. The average rate of nosocomial bloodstream infection was 8.3 episodes per 100,000 patient-days, and an average of 6.4% of them were caused by S. maltophilia. Malignancy was the most common underlying disease (32%). Six episodes of S. maltophilia bacteremia had soft tissue involvement, and only 1 of them underwent surgical intervention and survived. These 32 isolates were most susceptible to trimethoprim-sulfamethoxazole (91%), and no obvious increase in multidrug resistance was noted in the previous 10 years. The crude mortality rate was 40.6%. Malignancy, failure to remove central venous catheter, and ineffective antibiotic treatment were significant risk factors for mortality. CONCLUSIONS: Early and effective antimicrobial therapy and removal of central venous catheter as soon as possible are vital for the successful management of S. maltophilia bacteremia.     

血培养常见菌株的分布及金黄色葡萄球菌耐药性的分析

目的调查同济医院2006年1月至2008年12月血培养中常见非重复分离菌株的构成;分析金黄色葡萄球菌对常用抗菌药物的耐药性。方法采用WHONET5．4软件分析连续3年血培养中的非重复分离菌株的分布;采用K-B纸片法测定金黄色葡萄球菌对常用抗菌药物的敏感性。结果2006年1月至2008年12月共分离细菌1336株,其中革兰阳性球菌占58．5％（781／1336）、革兰阴性杆菌占37．2％（497／1336）、真菌占4．27％（57／1336）。分离的前10位菌株依次为凝固酶阴性葡萄球菌（CNS,40．42％）、大肠埃希菌（13．47％）、肠球菌属（5．54％）、克雷伯菌属（4．94％）、金黄色葡萄球菌（4．34％）、草绿链球菌（4．34％）、真菌（4．27％）、沙门菌属（3．59％）、铜绿假单胞菌（3．29％）、嗜麦芽窄食单胞菌（3．14％）。金黄色葡萄球菌共58株,其中甲氧西林耐药金黄色葡萄球菌（methicillinresistantStaphylococcusoltl-eus。MRSA）占44．8％（26／58）。MRSA对头孢菌素类、氨苄西林／舒巴坦、红霉素、克林霉素、复方新诺明、庆大霉素和左氧氟沙星、磷霉素、利福平耐药率明显高于甲氧西林敏感的金黄色葡萄球菌（methicillin—susceptibleStaphylococcuso,uFeus,MSSA）,且差异具有统计学意义（P〈0．001）。未发现对万古霉素和替考拉宁不敏感的菌株。结论本院血培养分离株中,凝固酶阴性葡萄球菌仍占据第一位。金黄色葡萄球菌占分离菌株第五位,其中MRSA检出率较高,且耐药性严重。MRSA病区的分布及耐药谱分析提示可能存在MRSA的克隆传播。     

深圳市龙岗区患者痰培养细菌菌谱和耐药性研究

目的研究深圳市龙岗区患者痰培养细菌菌谱和耐药性,为临床合理应用抗菌药物提供依据。方法对来自深圳市龙岗区4间医院2007年1月至2008年6月患者合格痰标本中培养的细菌药敏试验进行回顾性分析。结果727株细菌中,革兰阴性杆菌595株,占81．8％,以鲍曼不动杆菌、铜绿假单胞菌为主;革兰阳性球菌132株,占18．2％,以凝固酶阴性葡萄球菌、金黄色葡萄球菌为主,而且凝固酶阴性葡萄球菌株数超过金黄色葡萄球菌。药敏结果提示革兰阴性杆菌及革兰阳性球菌对相当多数的抗生素耐药率较高。结论深圳市龙岗区患者痰培养细菌耐药情况较严重,条件致病菌菌株数比例较高。应加强药物尤其是抗菌药物的使用管理,规范应用抗生素。     

重症监护室6400例血培养病原菌分布及药敏分析

目的对重症监护室6400例血培养的病原菌进行分离,并对菌株的分布及药敏进行分析。方法回顾调查2011年1月至2013年6月高州市人民医院ICU病房6400例患者的血样标本,并对其病原菌种类进行分离。采用BDBACTECTM9120全自动血培养仪对血液进行培养,BD—Phoenix-100全自动细菌鉴定仪对细菌的种类进行鉴定并对细菌的药敏性进行检测。结果6400例血样中共检出细菌971株,阳性率为15．17％。其中革兰阴性菌检出515株,占53．04％;革兰阳性菌425株,占43．77％;真菌31株,占3．19％。检出病原菌主要为大肠埃希菌、铜绿假单胞菌、金黄色葡萄球菌、表皮葡萄球菌、肺炎克雷伯菌以及肠球菌等。其中,葡萄球菌对于甲氧西林和青霉素的耐药性最大,大肠埃希菌、肺炎克雷伯菌以及铜绿假单胞菌对亚胺培南都有很好的受药性。结论阴性葡萄球菌、鲍曼不动杆菌等在重症监护室中属于多发常见的病原菌,该种菌的耐药性以及多重耐药性都非常普遍,临床上应根据药敏检测结果进行用药。     

2012年深圳市光明新区人民医院细菌耐药监测

目的了解2012年深圳市光明新区人民医院临床分离菌对常用抗菌药物的耐药性。方法采用Microscanauto4鉴定及药敏系统对临床常规细菌进行监测．按CLSl2009年版标准判断药敏结果．并用WHONET5．4软件统计分析。结果全年共分离细菌1818株,其中革兰阳性菌占35．6％,革兰阴性菌占58．O％。葡萄球菌中耐甲氧西林金黄色葡萄球菌（MRSA）占18．3％,凝固酶阴性葡萄球菌（MRCNS）占71．9％。肺炎链球菌中青霉素非敏感的肺炎链球菌（PNSSP）占20．7％。大肠埃希菌和肺炎克雷伯杆菌产ESBLs菌株分别占43．2％和22．4％。检出5株亚胺培南耐药的肠杆科细菌。铜绿假单胞菌和鲍曼不动杆菌对头孢他啶、哌拉西林、妥布霉素、阿米卡星、环丙沙星、亚胺培南的耐药率均低于10％。结论本院常见致病菌耐药性不是十分严重,尤其是院内感染的铜绿假单胞菌和鲍曼不动杆菌对常用抗菌药物耐药率较低。     

Analysis of methicillin resistance among Staphylococcus aureus blood isolates in an emergency department

The increasing prevalence of methicillin-resistant Staphylococcus aureus (MRSA) has become of great concern in both hospital and community settings. To evaluate the prevalence and risk factors for methicillin resistance among Staphylococcus aureus, blood isolates in our Emergency Department (ED) were collected. All patients with S. aureus bacteremia (SAB) who presented to the ED from January 2000 to August 2005 were included, and a retrospective study was performed. A total of 231 patients with SAB were enrolled (median age, 59 yr; M:F, 125:106). Among these patients, methicillin-resistant strains accounted for 27.3% (63 patients). Catheter-related infection was the most frequent primary site of SAB (39.0%), followed by skin and soft tissue infection (16.5%). In multivariate analysis, recent surgery (OR, 3.41; 95% CI, 1.48-7.85), recent hospitalization (2.17; 1.06-4.62), and older age (> or =61 yr) (2.39; 1.25-4.57) were independently associated with the acquisition of methicillin-resistant strains. When antimicrobial therapy is considered for the treatment of a patient with suspected SAB, clinicians should consider obtaining cultures and modifying empirical therapy to provide MRSA coverage for patients with risk factors: older age, recent hospitalization, and recent surgery.     

Bacteremia in HIV-infected patients: short-term predictors of mortality

To identify characteristics associated with mortality in HIV-infected patients with bacteremia, 88 bacteremic episodes in 80 HIV-infected patients were prospectively identified over a 5-month period and observed for 30 days. Demographic, clinical, laboratory, and radiologic data were collected. Mean and median age was 41 years. Most study subjects were homosexual men. Median CD4 count was 20 cells/mm3. Gram-positive organisms predominated (65%). The most common source of bacteremia was intravascular catheters (45%). Overall mortality was 30%. A history of malignancy, three or more opportunistic infections, shock, low hemoglobin, source of bacteremia other than an intravascular catheter, resistance to therapy, and a second bacteremic episode during the study period, were all found to be independent predictors of mortality. In this cohort of HIV-infected patients, most of whom were severely immunosuppressed, several factors were found to be significantly and independently associated with mortality.     

Epidemiology of community-acquired Staphylococcus aureus bacteremia.

Methicillin-resistant Staphylococcus aureus (MRSA) is an important nosocomial pathogen which has been isolated with increasing frequency in recent decades. Community-acquired MRSA (CA-MRSA) infections have also become increasingly important in recent years. This study retrospectively analyzed the risk factors, duration of hospitalization, yearly trend and seasonal variation in prevalence, and antibiotic susceptibility of isolates of community-acquired S. aureus (CASA) bacteremia and CA-MRSA bacteremia from patients treated in a teaching hospital in northern Taiwan. A total of 104 clinical isolates of CASA bacteremia were collected between January 1999 and December 2001. Among these, 35 (33.7%) were identified as MRSA. After multivariate analysis, the independent risk factors for developing CA-MRSA bacteremia were diabetes mellitus (p=0.028), chronic obstructive lung disease (p=0.037), and renal insufficiency (p=0.041). Only 6 (17.1%) patients in the MRSA group had no identified risk factors. Most of the isolates of CA-MRSA had a high degree of resistance to most antibiotics, including clindamycin (71.4%), trimethoprim-sulfamethoxazole (65.7%), and chloramphenicol (41.2%). No major trend or seasonal variation in the prevalence was found during the study period. No difference in mortality related to resistance pattern was found. Although CA-MRSA is not the major pathogen in community-acquired bacteremia, it should be included in the differential diagnosis of Gram-positive bacterial bloodstream infection, especially in those patients with risk factors. Early empiric therapy with glycopeptides in these patients may reduce morbidity and mortality.     

Comparison of lysis-centrifugation with a biphasic blood culture medium for the recovery of aerobic and facultatively anaerobic bacteria

The Du Pont Isolator tube and Roche Septi-Chek blood culture bottle employ solid media which facilitate the removal of bacteria from static or cidal substances in blood to increase recovery and decrease detection time. In a comparison of 11,567 blood culture sets, the Isolator tube and vented Roche Septi-Chek bottle were positive for 533 (80%) and 494 (74%) of the aerobic and facultatively anaerobic organisms recovered, respectively. This difference was not significant. A significant difference was found in the overall detection time. The Isolator tube recovered the bacteria ca. 1 day earlier. The earlier detection time was most notable with Staphylococcus aureus, viridans streptococci, and Pseudomonas aeruginosa. Among the 355 bacteremic episodes analyzed by a computer program, the Isolator tube was responsible more often for the first report of bacteremia in a given patient. Both systems performed well for the recovery of aerobic and facultatively anaerobic bacteria, but it is recommended that either be used in combination with an unvented broth-containing bottle.     

Further increase of vancomycin-resistant Enterococcus faecium, amikacin- and fluoroquinolone-resistant Klebsiella pneumoniae, and imipenem-resistant Acinetobacter spp. in Korea: 2003 KONSAR surveillance

Monitoring temporal trends of antimicrobial resistance can provide useful information for the empirical selection of antimicrobial agents to treat infected patients and for the control of nosocomial infections. In this study, we analyzed antimicrobial resistance of clinically relevant bacteria in 2003 at Korean hospitals and at a commercial laboratory. The following organism-antimicrobial agent resistance combinations were very prevalent: oxacillin-resistant Staphylococcus aureus (68%), expanded-spectrum cephalosporin-resistant Klebsiella pneumoniae (25%), and fluoroquinolone-resistant Escherichia coli (33%), Acinetobacter spp. (58%), and Pseudomonas aeruginosa (40%). Moreover, gradual increases in vancomycin-resistant Enterococcus faecium (20%), cefoxitin-resistant E. coli (10%) and K. pneumoniae (23%), and imipenem-resistant P. aeruginosa (20%) and Acinetobacter spp. (13%) were also observed. The resistance rates of Acinetobacter spp. to most antimicrobial agents at hospitals and at the commercial laboratory were similar. Among the Acinetobacter spp. isolated at a tertiary-care hospital, 46.2% were multidrug-resistant to 9-12 of 13 antimicrobial agents, and 18.3% were panresistant. The exclusion of duplicate isolates at a tertiary-care hospital significantly lowered the proportion of oxacillin-resistant S. aureus, vancomycin-resistant E. faecium, and fluoroquinolone-resistant E. coli.     

Identification and characterization of bacterial pathogens causing bloodstream infections by DNA microarray

Bloodstream infections are potentially life-threatening and require rapid identification and antibiotic susceptibility testing of the causative pathogen in order to facilitate specific antimicrobial therapy. We developed a prototype DNA microarray for the identification and characterization of three important bacteremia-causing species: Staphylococcus aureus, Escherichia coli, and Pseudomonas aeruginosa. The array consisted of 120 species-specific gene probes 200 to 800 bp in length that were amplified from recombinant plasmids. These probes represented genes encoding housekeeping proteins, virulence factors, and antibiotic resistance determinants. Evaluation with 42 clinical isolates, 3 reference strains, and 13 positive blood cultures revealed that the DNA microarray was highly specific in identifying S. aureus, E. coli, and P. aeruginosa strains and in discriminating them from closely related gram-positive and gram-negative bacterial strains also known to be etiological agents of bacteremia. We found a nearly perfect correlation between phenotypic antibiotic resistance determined by conventional susceptibility testing and genotypic antibiotic resistance by hybridization to the S. aureus resistance gene probes mecA (oxacillin-methicillin resistance), aacA-aphD (gentamicin resistance), ermA (erythromycin resistance), and blaZ (penicillin resistance) and the E. coli resistance gene probes blaTEM-106 (penicillin resistance) and aacC2 (aminoglycoside resistance). Furthermore, antibiotic resistance and virulence gene probes permitted genotypic discrimination within a species. This novel DNA microarray demonstrates the feasibility of simultaneously identifying and characterizing bacteria in blood cultures without prior amplification of target DNA or preidentification of the pathogen.