Antimicrobial use and methicillin-resistant Staphylococcus aureus in a large nursing home

INTRODUCTION: In 1997, 18% of Staphylococcus aureus clinical isolates at the Wisconsin Veterans Home were resistant to methicillin. By 2002, 51% were resistant. METHODS: We determined the antibiotic sensitivity pattern of our methicillin-resistant S. aureus (MRSA) isolates as well as changes in utilization of specific antibiotics between two time periods. We reasoned that antibiotics with activity against methicillin-sensitive S. aureus (MSSA), but not MRSA, might be driving the overgrowth of MRSA. RESULTS: In our facility, MRSA is usually resistant to quinolones; MSSA is usually sensitive. Both MSSA and MRSA are usually sensitive to TMP-sulfa. An increased percentage of S. aureus resistant to methicillin (18%) was associated with a 42% increase in quinolone use and a 37% decrease in TMP-sulfa use. CONCLUSION: Our analysis and previous reports suggest that replacement of TMP-sulfa by quinolones could be selecting MRSA in our facility. This conclusion, however, is speculative, based on association, and requires confirmation.     

Epidemiology of methicillin-resistant Staphylococcus aureus at a children's hospital.

OBJECTIVE: To describe the relative contribution of and risk factors for both community-acquired and nosocomial methicillin-resistant Staphylococcus aureus (MRSA) infections. DESIGN: Retrospective cohort study. SETTING: 270-bed, tertiary-care children's hospital. PARTICIPANTS: All MRSA-infected children from whom MRSA was recovered between October 1, 1999, and September 30, 2001. METHODS: Demographic, clinical, and risk factor data were abstracted from medical records. Categorical variables were analyzed using the chi-square or Fisher's exact test and continuous variables were analyzed using the Mann-Whitney test. RESULTS: Of the 62 patients with new MRSA infection, 37 had community-acquired MRSA and 25 had nosocomial MRSA. Most community-acquired MRSA infections were of the skin and soft tissue, the middle ear, and the lower respiratory tract. Nosocomial MRSA infections occurred in the lower respiratory tract, the skin and soft tissue, and the blood. Risk factors for infection, including underlying medical illness, prior hospitalization, and prior surgery, were similar for patients with community-acquired MRSA and nosocomial MRSA. History of central venous catheterization and previous endotracheal intubation was more common in patients with nosocomial MRSA. Only 3 patients with community-acquired MRSA had no identifiable risk factor other than recent antibiotic use. Resistance for clindamycin, erythromycin, and levofloxacin was similar between strains of community-acquired MRSA and nosocomial MRSA. CONCLUSIONS: Similarities in patient risk factors and resistance patterns of isolates of both community-acquired and nosocomial MRSA suggest healthcare acquisition of most MRSA. Thus, classifying MRSA as either community acquired or nosocomial underestimates the amount of healthcare-associated MRSA.     

The epidemiology of mupirocin resistance among methicillin-resistant Staphylococcus aureus at a Veterans' Affairs hospital.

OBJECTIVE: To describe the clinical and molecular epidemiology of mupirocin-resistant (MR) and mupirocin-susceptible (MS) methicillin-resistant Staphylococcus aureus (MRSA) at a Veterans' Affairs hospital and to assess risk factors associated with the acquisition of MR MRSA. DESIGN: All clinical MRSA isolates for the period October 1990 through March 1995 underwent susceptibility testing to mupirocin. Mupirocin resistance trends were measured, and MS MRSA and MR MRSA isolates underwent typing by pulsed-field gel electrophoresis (PFGE). A retrospective case-control study was conducted to evaluate risk factors for having MR versus MS MRSA. SETTING: The James H. Quillen Veterans' Affairs Medical Center in Mountain Home, Tennessee, included a 324-bed acute-care hospital, a 120-bed nursing home, and a 525-bed domiciliary. Colonizations and infections with MRSA were endemic, and mupirocin ointment was commonly used. PATIENTS: Inpatients and outpatients at the facility. RESULTS: MS MRSA was recovered from 506 patients and MR MRSA from 126. Among MR MRSA isolates, 58% showed low-level mupirocin resistance (minimum inhibitory concentration [MIC] > or = 4 to 256 microg/mL), and 42% showed high-level mupirocin resistance (MIC > or = 512 microg/mL). A significant increase (P=.002) in the number of high-level MR isolates occurred during the 1993 to 1995 period. A case-control study showed that presence of a decubitus ulcer correlated with high-level resistant isolates (P<.05). The distribution of PFGE patterns did not differ for MR and MS MRSA CONCLUSIONS: Use of mupirocin ointment in a program aimed at managing endemic MRSA infection or colonization resulted in a significant increase in the recovery of high-level MR MRSA isolates. These isolates appeared to emerge from our existing MRSA pool. A case-control study provided few clues concerning patients likely to harbor MR MRSA. We confirmed the position that the extended use of mupirocin ointment should be avoided in settings where MRSA is endemic.     

A longitudinal analysis of methicillin-resistant Staphylococcus aureus in a Hong Kong teaching hospital.

OBJECTIVES: To review the incidence and trends of MRSA during a 12-year (1989-2000) period at a university teaching hospital and the relationship between strain distribution by antibiogram and molecular typing. DESIGN: Retrospective review of laboratory-based surveillance records on MRSA isolation and characterization of strains by antimicrobial susceptibility and PFGE. A patient episode was counted at the time when MRSA was first isolated. SETTING: A 1,350-bed university teaching hospital in Hong Kong. PATIENTS: Those with clinical isolates of MRSA. RESULTS: During 1989 to 2000, the hospital recorded 1,203,175 deaths and discharges (D&D) and encountered 5,707 patient episodes of new MRSA isolation. The overall incidence of patient episodes of MRSA was 0.47/100 D&D. In 1989, the incidence was 0.81/100 D&D and fell to a low of 0.33/100 D&D in 1995, but then rose to 0.50/100 D&D in 2000. Antibiogram and DNA typing identified 5 major types. PFGE type A constituted 68% (211/312) of isolates and was present throughout the 12-year period. PFGE type B constituted 13% (40/312) of isolates and was only present from 1995 to 2000. These isolates form a distinct clone and had unique antibiotic resistance profiles. CONCLUSIONS: The study showed the establishment of a dominant MRSA clone (PFGE type A group) in the intensive care, medical, and surgical units and the appearance of a new MRSA strain in 1995 (PFGE type B), which partly explained the rise in incidence of MRSA cases and a disproportionate rise in MRSA bacteremia from 1995 to 2000.     

Ten years' experience with methicillin-resistant Staphylococcus aureus in a large Australian hospital.

The Royal Brisbane Hospital (RBH) is a 1200-bed teaching hospital with acute, general and specialist units for adult patients. Methicillin-resistant Staphylococcus aureus (MRSA) was first detected at the RBH in 1975 and the number of new patients colonized and infected increased from one in 1975 to 720 in 1989, with a peak of 811 in 1987. Virulence may be inferred from blood culture isolates. Between 1979 and 1989 the number of patients with S. aureus bacteraemia increased from 40 to 138 per year. The percentage of these isolates which were MRSA varied from a low of 4% in 1980 to a peak of 37% in 1984 with 28% in 1989. The control attempts, sensitivity patterns, sources of the isolates and their probable impact and importance will be discussed.     

一所大型教学医院临床分离肺炎链球菌耐药性分析

目的了解一所大型教学医院临床分离的肺炎链球菌临床分布及耐药情况,为临床合理使用抗菌药物,预防和控制感染提供依据。方法收集中南大学湘雅医院2010年11月-2012年11月临床标本分离的肺炎链球菌192株,均经全自动细菌鉴定仪鉴定。采用K B法检测其对常用14种抗菌药物的敏感性,琼脂稀释法检测青霉素的最低抑菌浓度(MIC)。结果肺炎链球菌主要分离自儿科（36.98%）,标本主要为痰液（64.07%）;患者年龄呈双峰分布,以＜5岁和＞50岁的感染者较多。肺炎链球菌对红霉素、氯霉素、四环素、克林霉素耐药率均＞80%。192株肺炎链球菌青霉素MIC范围为0.015～≥32.0 μg/mL,其中MIC50为2.0 μg/mL,MIC90为16.0 μg/mL。非侵袭性肺炎链球菌耐药性高于侵袭性肺炎链球菌。结论该院肺炎链球菌耐药情况较为严重,在临床上对肺炎链球菌的治疗应重视青霉素耐药菌株的出现。     

综合性医院金黄色葡萄球菌分布及耐药趋势

目的了解医院金黄色葡萄球菌临床分布及耐药性,为合理应用抗菌药物提供依据。方法收集2008-2011年医院临床与门诊患者送检标本分离出的金黄色葡萄球菌,细菌鉴定采用VITEK微生物分析仪,药物敏感性试验采用BIOMIC药敏测定仪,耐药性分析采用WHONET5.4软件。结果近4年医院检出金黄色葡萄球菌1 252株,其中MRSA 898株占71.7%;金黄色葡萄球菌检出以痰液标本为主占63.3%,检出病区内科36.5%、外科12.4%;内科病区除磺胺甲噁唑/甲氧苄啶和左氧氟沙星外,对其他抗菌药物耐药率均高于外科病区;金黄色葡萄球菌对利奈唑胺和万古霉素未发现耐药株,对呋喃妥因和磺胺甲噁唑/甲氧苄啶耐药率<30.0%;对青霉素耐药率>90.0%,痰标本中金黄色葡萄球菌对抗菌药物的耐药率除利奈唑胺、万古霉素、呋喃妥因、磺胺甲噁唑/甲氧苄啶外均高于总标本中金黄色葡萄球菌的耐药率。结论 MRSA耐药性高,应规范临床用药,加强MRSA耐药性监测,有效控制感染。     

Epidemiological study of Staphylococcus aureus resistance to new quinolones in a university hospital.

During a 14-month period, from December 1984 to February 1986, 630 Staphylococcus aureus isolates were identified at Broussais Hospital. Thirty-eight isolates (6%), from 35 patients, were found to be pefloxacin-resistant S. aureus (PRSA) with minimal inhibitory concentrations greater than or equal to 8 mg l-1. PRSA isolates were tested for susceptibility to 35 antibiotics, including nine quinolones, and heavy metal ions. Phage-type was determined. Out of the 38 PRSA isolates, 35 (92%) were methicillin- and multiply-resistant; however, all PRSA isolates were sensitive to vancomycin and coumermycin. Fifteen isolates (39%) had similar phage-type and identical antibiotic susceptibility pattern with high level resistance to pefloxacin (MICs equal to 64 mg l-1); they were isolated from the same surgical unit. The 23 remaining PRSA isolates differed by their phage and susceptibility patterns. Pefloxacin MICs ranged from 8 to 512 mg l-1 with a bimodal distribution; cross-resistance was observed with the eight other quinolones tested. Only nine PRSA isolates (24%), including four 'epidemic' isolates, were obtained from patients who had been treated with quinolones. From these data there is apparently no direct relationship between quinolone administration and selection of PRSA in infected patients.     

Epidemiology of methicillin-resistant Staphylococcus aureus at a university hospital in the Canary Islands.

OBJECTIVES: To describe the epidemiology of methicillin-resistant Staphylococcus aureus (MRSA) at a university hospital in Tenerife, Canary Islands, during a 40-month period and to evaluate the effectiveness of the application of control measures. DESIGN: Laboratory-based surveillance, medical charts and microbiological records review, and characterization of strains by pulsed-field gel electrophoresis (PFGE) were used to describe the epidemiology. Infection control practices were introduced as an intervention. SETTING: A 650-bed, tertiary-care university hospital. SUBJECTS: Patients with clinical and nasal isolates of MRSA and colonized staff members. RESULTS: The rate of nosocomial MRSA infections was 32.5% for 1997, 17.9% for 1998, 14.5% for 1999, and 25.6% during the first 4 months of 2000. The major sites of isolation for nosocomial MRSA infection included surgical wounds (25%) and the lower respiratory tract (24%). Intensive care units and surgical specialties had more frequent MRSA cases. Characteristics associated with nosocomial MRSA isolates included prior use of intensive antibiotic therapy, prolonged hospital stays, major underlying illness, invasive procedures, and older age. PFGE type A (subtype A1) was the strain most frequently found and the only PFGE type involved in clusters. CONCLUSIONS: Surveillance cultures and contact droplet precautions were followed by decreased rates for 2 years. Nevertheless, the spread of PFGE subtype A1 to many different areas of the hospital and the increase in incidence during the first third of 2000 indicates either that surveillance cultures were not used widely enough or that compliance with isolation measures was suboptimal.     

Rapid dissemination of Staphylococcus aureus with classic oxacillin resistance phenotype at a new university hospital

To determine the prevalence rates of oxacillin-resistant Staphylococcus aureus (ORSA) at a new university hospital since its opening, the results of disk diffusion tests on all clinical isolates, recovered between 1990 and 1998 at the National Cheng Kung University Hospital, were reviewed. In order, to investigate the mechanisms of oxacillin resistance among strains of S. aureus in Taiwan, MICs were determined by an agar dilution method, and polymerase chain reaction and colony hybridization assays were performed on 288 isolates collected during November 1998 to detect the mecA gene. The prevalence rates of ORSA increased rapidly from 14.1% in 1990 to 61.0% in 1998. The increasing rates were most rapid in the first four-year period, ranging from 11.6 to 106.7% per year, and became steady after 1994, ranging from 1.8% to 11.6%. Of 288 clinical isolates collected in November 1998, 206 (71.5%) were resistant to oxacillin (MIC >/= 16 mg/L), and four were borderline resistant (MIC 2-8 mg/L). All 210 strains possessed the mec A gene (classic resistance). The present study demonstrated that ORSA could disseminate in a new hospital with great speed, and indicated that all ORSA strains in Taiwan revealed classic resistance phenotype.     

Methicillin-resistant Staphylococcus aureus: a 5-year review of surveillance data in a tertiary care hospital in Saudi Arabia.

BACKGROUND: Staphylococcus aureus is an important pathogen that leads to serious infections in the community and in hospitals. Evidence has shown that the prevalence of infection and colonization with drug-resistant S. aureus, such as methicillin-resistant S. aureus (MRSA) and glycopeptide intermediately susceptible S. aureus, is increasing. Authorities must be aware of the prevalence of MRSA infection and colonization in their country in order to implement and monitor infection control policies that help curtail further emergence of this pathogen. OBJECTIVES: To examine the trend of hospital-acquired MRSA infection and colonization in a tertiary care institution in Saudi Arabia during a 5-year period in order to identify specific areas at high risk for MRSA transmission, and to review our MRSA decolonization procedure and outcomes. METHODS: Surveillance data prospectively collected from January 1, 2000, through December 31, 2004, on hospital-acquired (HA) MRSA were analyzed, with an emphasis on the trend of HA-MRSA infection and colonization, areas of high transmission, risk factors, and effectiveness of the implemented decolonization policy. RESULTS: During the study period, 442 cases of HA-MRSA infection and colonization were identified. Of these, 51.2% were infections, and 48.8% were colonizations. An increasing trend in the incidence rates of infection and colonization was noticed during the study period, and most cases were identified on the surgical ward (33.3%) and medical ward (32.1%). Of the 34 infected patients who underwent systematic decolonization, 35.3% were successfully decolonized, and of the 11 who underwent topical decolonization, 63.6% were successfully decolonized. CONCLUSION: The increasing trend of HA-MRSA infections has been a noticeable global problem. We identified a gradual increase in the rates of MRSA colonization and infection in a tertiary care center Saudi Arabia and recognize the importance of abiding by strict infection control policies, including hand hygiene and proper isolation practices. Continued surveillance for MRSA and other emerging multidrug-resistant pathogens is also needed.     

Staphylococcus aureus colonization among healthcare workers at a tertiary care hospital.

We describe the epidemiology of Staphylococcus aureus colonization among 200 healthcare workers. The prevalence of S. aureus was 28%, and the prevalence of methicillin-resistant S. aureus (MRSA) was 2%. The incidence of MRSA colonization was extremely low. This study suggests that the risk of MRSA transmission to healthcare workers is low in a hospital where MRSA is endemic.     

Nosocomial bacteremia in children: a 15-year experience at a general hospital in Mexico.

OBJECTIVE: To describe the incidence and etiology of nosocomial bloodstream infections in children at a general hospital. DESIGN: Review of nosocomial bloodstream infections detected in children during 1991-2005. Data were prospectively gathered through active surveillance. Annual rates of infection were compared. SETTING: A public general hospital in San Luis Potosi, Mexico. PATIENTS: Children younger than 15 years of age admitted to pediatric wards and subjected to prospective surveillance for nosocomial infection. INTERVENTIONS: Measures instituted to decrease the incidence of hospital-acquired infection during the 15-year study period included establishing active surveillance for hospital-acquired infection, reinforcing compliance with handwashing recommendations, decreasing the degree of crowding on wards, establishing guidelines for the management of intravenous catheters and solutions, preparing parenteral nutrition and intravenous solutions under a laminar air-flow hood, and increasing nursing personnel. RESULTS: There were 868 nosocomial bloodstream infections detected in 29,273 subjects (overall rate, 2.94 episodes per 100 discharges). Infection rates were greatest among children admitted to the neonatal intensive care unit and lowest for those admitted to the school-age ward and the infectious diseases ward. There was a significant decrease in rates of nosocomial bacteremia in all of the wards. The organisms isolated most commonly were Klebsiella pneumoniae, Candida species, and coagulase-negative staphylococci. Mortality rates were higher for children with a gram-negative bacterial bloodstream infection (45.2%) and lower for children with a gram-positive bacterial infection (19.2%).Conclusions. Rates of nosocomial bloodstream infection decreased over the past 15 years at our hospital but continue to cause significant mortality. Continuing efforts to decrease the frequency of and mortality due to bloodstream infection are warranted.     

Staphylococcus aureus colonization of the newborn in a Darlington hospital.

Evidence from research studies suggests a relationship between neonatal infection with Staphylococcus aureus and the level of umbilical colonization. During a 3-month prospective study (September-December 1990) the incidence and levels of S. aureus colonization were determined for all 370 live births in the Darlington Unit by taking swabs at 48 h and 8/9 days from the base of the umbilical cord. Infants were situated in one of four locations (The Special Care Unit, one of two wards or home) and the location at the time of swabbing was recorded. The overall percentages colonized at 48 h and 8/9 d were 68% and 65% respectively. Forty-eight hours after delivery, 49% showed a high level of S. aureus colonization. Although the percentage of infants colonized with S. aureus was almost identical at each sampling, only 62% were culture-positive on both occasions. Between 48 h and 8/9 days, 12% (44) of infants developed S. aureus infections of whom 35 showed heavy growth. Statistical analysis showed a significant relationship between levels of colonization at the two sampling times but no relationship between location and levels of colonization over the time period.     

Role of healthcare workers in outbreaks of methicillin-resistant Staphylococcus aureus: a 10-year evaluation from a Dutch university hospital.

BACKGROUND AND OBJECTIVE: The benefit of screening healthcare workers (HCWs) at risk for methicillin-resistant Staphylococcus aureus (MRSA) carriage and furloughing MRSA-positive HCWs to prevent spread to patients is controversial. We evaluated our MRSA program for HCWs between 1992 and 2002. SETTING: A university medical center in The Netherlands, where methicillin resistance has been kept below 0.5% of all nosocomial S. aureus infections using active surveillance cultures and isolation of colonized patients. DESIGN: HCWs caring for MRSA-positive patients or patients in foreign hospitals were screened for MRSA. MRSA-positive HCWs had additional cultures, temporary exclusion from patient-related work, assessment of risk factors for persisting carriage, decolonization therapy with mupirocin intranasally and chlorhexidine baths for skin and hair, and follow-up cultures. RESULTS: Fifty-nine HCWs were colonized with MRSA. Seven of 840 screened employees contracted MRSA in foreign hospitals; 36 acquired MRSA after contact with MRSA-positive patients despite isolation precautions (attack rate per outbreak varied from less than 1% to 15%). Our hospital experienced 17 MRSA outbreaks, including 13 episodes in which HCWs were involved. HCWs were index cases of at least 4 outbreaks. In 8 outbreaks, HCWs acquired MRSA after caring for MRSA-positive patients despite isolation precautions. CONCLUSION: Postexposure screening of HCWs allowed early detection of MRSA carriage and prevention of subsequent transmission to patients. Where the MRSA prevalence is higher, the role of HCWs may be greater. In such settings, an adapted version of our program could help prevent dissemination.     

医院环境与住院患者耐甲氧西林金黄色葡萄球菌分布与耐药性分析

目的了解耐甲氧西林金黄色葡萄球菌(MRSA)在医院内的流行及耐药情况,为MRSA医院感染的预防与控制提供科学依据。方法以某三级甲等综合医院2010年6-12月,医院环境分离的40株金黄色葡萄球菌(SAU),与临床标本分离的155株SAU为研究对象,采用K-B纸片法进行MRSA鉴定与药物敏感性试验。结果 195株SAU中,MRSA检出率为88.72%,其中临床分离株和环境分离株中的MRSA检出率分别为88.39%和90.00%,两者相比差异无统计学意义;临床MRSA株,主要分布于痰液及伤口分泌物;环境MRSA株主要分布于病房空气及病床架与床旁桌;MRSA对β-内酰胺类抗菌药物耐药率为100.00%,万古霉素的敏感率为100.00%,对其他抗菌药物不同程度耐药。结论 MRSA在医院内有较高的流行度,且呈多药耐药性,应长期进行MRSA感染目标性监测,切实做好MRSA感染或定植患者的消毒隔离工作。     

Antimicrobial susceptibility of Staphylococcus aureus isolated from hospital inpatients, 2009: report from the Australian Group on Antimicrobial Resistance

In 2009, the Australian Group on Antimicrobial Resistance (AGAR) conducted a period-prevalence survey of clinical Staphylococcus aureus isolated from hospital inpatients. Thirty medical microbiology laboratories from each state and mainland territory participated. Specimens were collected more than 48 hours post-admission. Isolates were tested by Vitek2 (AST-P579 card) and by Etest for daptomycin. Nationally, the proportion of S. aureus that were MRSA was 33.6%, ranging from 27.3% in South Australia to 41.4% in New South Wales/Australian Capital Territory. Resistance to the non-beta-lactam antimicrobials was common except for rifampicin, fusidic acid, daptomycin and high-level mupirocin. No resistance was detected for vancomycin, teicoplanin, quinupristin-dalfopristin or linezolid. Resistance in the methicillin susceptible S. aureus (MSSA) was rare apart from erythromycin (12%) and absent for vancomycin, teicoplanin, daptomycin, quinupristin-dalfopristin and linezolid. The proportion of methicillin resistant S. aureus (MRSA) has remained stable since the first AGAR inpatient survey in 2005 yet during the same time frame resistance to many antimicrobials, in particular tetracycline, trimethoprim-sulphamethoxazole and gentamicin, has significantly decreased. This suggests that non-multi-resistant community-associated MRSA (CA-MRSA) clones are becoming more common in the hospital setting and replacing the long-established multi-resistant clones such as ST239-III (Aus 2/3 EMRSA). Given hospital outbreaks of CA-MRSA are thought to be extremely rare it is most likely that patients colonised at admission with CA-MRSA have become infected with the colonising strain during their hospital stay.