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Virtually all methicillin-resistant Staphylococcus aureus (MRSA) infections in the largest Portuguese teaching hospital are caused by two internationally spread multiresistant strains: the 'Iberian' and the 'Brazilian' clones of MRSA.

OBJECTIVE: To determine the nature (clonal type and antibiotic resistance pattern) of methicillin-resistant Staphylococcus aureus (MRSA) strains recovered from the largest teaching hospital in Portugal and to detect temporal trends in clonal types during three consecutive surveillance periods in 1992--93, 1994--95 and 1996. METHODS: MRSA strains were characterized by chromosomal SmaI macrorestriction patterns using pulsed-field gel electrophoresis (PFGE) and by DNA fingerprints---applied to ClaI digests---capable of probing two specific areas of the staphylococcal chromosome: (1) the vicinity of the mecA gene, and (2) the attachment site(s) and copy number of transposon Tn554. The combination of these methods can generate 'clonal types' useful for epidemiological tracking of MRSA strains. RESULTS: During the 1992--93 collection period, 65% of MRSA strains carried the mecA polymorph I, Tn554 pattern E and PFGE pattern A (I::E::A)---a clonal type that was used to define the 'Iberian MRSA', which is widely spread throughout southern Europe. The representation of this clone decreased to 42% in 1994--95 and to 20% in 1996. At the same time, a second multiresistant MRSA strain carrying mecA polymorph XI, Tn554 type B and PFGE pattern B (XI::B::B)---a clonal type characteristic of the so-called 'Brazilian MRSA'---increased from 5% in 1992--93 to 36% in 1994--95 and 29% in 1996. CONCLUSIONS: Throughout the four years of surveillance, the Iberian and Brazilian MRSA types and their single subtype variants together have been responsible for the overwhelming majority (close to 90%) of all MRSA infections in the largest teaching hospital of Portugal. The mechanism of epidemicity of these two multiresistant international MRSA clones remains to be elucidated.

Journal Article↗

[Studies on the relationship between gastric acidity and the development of MRSA. Especially for the prevention of MRSA enterocolitis].

Enterocolitis caused by methicillin-resistant Staphylococcus aureus (MRSA) has recently been recognized as one of the severe postoperative complications in surgery on the digestive organs. This disease often occurs in the early days after gastrointestinal operation, especially after gastrectomy. MRSA enterocolitis seems to occur when MRSA has first infected the naso-pharyngeal mucosa preoperatively, and then moved into the stomach, and subsequently proliferated in the higher pH gastric juices. The aim of this experiment was to reveal the relationship between the acidity of gastric juices and bacterial growth in the stomach during the pre and post operative period in an effort to prevent of MRSA enterocolitis. In vitro, MRSA was cultured for various periods at various pH values, and its proliferation was observed. MRSA did not grow in the culture at pH 1 at all, neither did it grow at pH 2 when cultured for more than 8 hours. This data shows the germicidal effect of high acidity in the stomach. Clinically, twenty patients with cancer in the digestive tract had the bacteria in their gastric juices examined in terms of acidity before and after operation. In cases with an increased pH level in the gastric juices after the operation. S. aureus including MRSA, was isolated frequently from the stomach. In vitro, incubation of MRSA with gastric juices collected from those cases showed no development of MRSA when the pH was below 3.98. In order to prevent the onset of MRSA enterocolitis, the remnant stomachs of ten patients with stomach cancer were filled with hydrochloric acid lemonade just after operative reconstruction.(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗

Incidence of methicillin-resistant Staphylococcus aureus (MRSA) isolation in a skilled nursing home: a third report on the risk factors for the occurrence of MRSA infection in the elderly.

A case control study was carried out in order to evaluate the various factors which may influence the occurrence of methicillin-resistant Staphylococcus aureus (MRSA) infections in a skilled nursing home. From April 1991 to March 1994, bacterial cultures were performed in 55 out of 102 residents in a nursing home based on various clinical aspects. We divided 102 residents into following three groups; (1) the MRSA group (n = 10), residents whose materials for bacterial culture were positive for MRSA, (2) the non-MRSA group (n = 45), residents whose specimens were negative for MRSA but positive for other bacteria, (3) the control group (n = 47), residents who did not have to undergo a bacterial culture because they were free from moderate and severe infectious diseases. Compared with the control group, the activities of daily living score and the serum albumin level were significantly lower in the MRSA group and the non-MRSA group at the beginning of the study. In contrast, the number of antibiotics used prior to the bacterial culture and the proportion of hospitalization within 6 months prior to the bacterial culture were significantly larger in the MRSA group than in either the non-MRSA group, or the control group. These results thus suggest that a low activities of daily living score, the use of many kinds of antibiotics and a recent previous hospitalization may be risk factors of MRSA infection in a nursing home environment.

Aged↗

[The effect of handwashing improving program and MRSA carrier screening program on the MRSA infection rates in an intensive care unit].

PURPOSE: To assess the effect of handwashing improving program and MRSA carrier detection program on MRSA(methicillin resistant Staphylococcus aureus) infection rate in a intensive care unit. METHOD: The intervention was Nosocomial Infection(NI) control program consisted of hand washing improving program and identification and treatment of MRSA carrier. Data on the NI and MRSA infections were collected by an infection control nurse based on the definition of CDC. MRSA infection rates were calculated by the number of MRSA infection per 100 admissions or 1,000 patients-days. The difference of MRSA infection rates between pre and post intervention was tested by Chi-square at =.05. RESULT: MRSA infection rates 3.0% or 3.2 per 1,000 patient-days at the pre, 4.6% or 3.7 per 1,000 patient-days at the post, and the differences were not statistically significant (p=.411, p=.769 respectively). CONCLUSION: The handwashing improving program and MRSA carrier detection program was not effective in reducing the Nosocomial Infection(NI) or MRSA infection rates. It is recommended further studies with a longer intervention and follow-up period.

English Abstract↗

[Experiences of postoperative staphylococcal enteritis caused by methicillin-cephem resistant Staphylococcus aureus (MRSA) and the state of the isolation of MRSA].

During the last 12 months, three cases of postoperative staphylococcal enteritis were experienced in our surgical ward. Kanamycin, Clindamycin and Latamoxef were given prophylactically in all cases. They developed dehydration with severe diarrhea and paralytic ileus in three to ten days after abdominal surgery. MRSA was cultured from the intestinal fluid or feces and Minocycline, sensitive anti-microbial agent to the organism, was administered intravenously and their conditions improved dramatically. Since the nosocomial infections of MRSA are believed to be the cause of these cases, following items were investigated; 1) the frequency of MRSA among Staphylococcus aureus clinically isolated from patients in surgical ward, 2) the state of nasal carriage of MRSA in medical staffs and inpatients without infections in surgical ward, 3) drug sensitivity of MRSA to ten kinds of antibiotics. The results were as follows; 1) the frequency of MRSA was 83% of all the strains of Staphylococcus aureus, 2) the nasal carrier status was 2 in 46 medical staffs and 4 in 17 inpatients, 3) 124 strains of MRSA, 114 isolated from patients and 10 from nasal carriers, showed the identical drug sensitivity, that is, MRSA is sensitive to Minocycline and resistant to every other antibiotics. It is believed that these three cases were due to nosocomial infections of MRSA, and early diagnosis of MRSA enteritis should lead to early antibiotic therapy and to a cure of this serious postoperative complication.

Adult↗

Spread of methicillin-resistant Staphylococcus aureus (MRSA) among household contacts of individuals with nosocomially acquired MRSA.

OBJECTIVE: To determine the frequency with which methicillin-resistant Staphylococcus aureus (MRSA) is spread from colonized or infected patients to their household and community contacts. DESIGN: Retrospective cohort study. SETTING: University hospital. PARTICIPANTS: Household and community contacts of MRSA-colonized or -infected patients for whom MRSA screening cultures were performed. RESULTS: MRSA was isolated from 25 (14.5%) of 172 individuals. Among the contacts of index patients who had at least one MRSA-colonized contact, those with close contact to the index patient were 7.5 times more likely to be colonized (53% vs 7%; 95% confidence interval, 1.1 to 50.3; P = .002). An analysis of antimicrobial susceptibility and DNA fingerprint patterns suggested person-to-person spread. CONCLUSIONS: MRSA colonization occurs frequently among household and community contacts of patients with nosocomially acquired MRSA, suggesting that transmission of nosocomially acquired MRSA outside of the healthcare setting may be a substantial source of MRSA colonization and infection in the community.

Adolescent↗

[Epidemiological studies on drug-resistance patterns, coagulase types, and MRSA-phage types of MRSA isolates during 1990-1994].

We examined drug-resistance patterns, coagulase types, and MRSA-phage types of 125 MRSA strains isolated from clinical specimens during the period of January 1990 and December 1994. No vancomycin-resistant strain was isolated. Twenty one antibiotics were divided into three classes, low-intermediate- and high-isolation-frequency class, based on isolation frequencies of resistant strains. Minocycline, chloramphenicol, streptomycin, and imipenem were found to be included in low-isolation-frequency class (16.8-40%). In intermediate-isolation-frequency class (45.6-62.9%), cefmetazole, amikacin, gentamicin, and tetracycline were included. Oxacillin, ampicillin, piperacillin, ceftizoxime, cefoperazone, cefazolin, erythromycin, oleandomycin, kitasamycin, clindamycin, kanamycin, tobramycin, and ofloxacin belonged to high-isolation-frequency class (97.6-100%). MIC90s of vancomycin and minocycline (1.56 and 25 micrograms/ml) were lower than that of other 13 drugs. Comparing medical ward with dental ward, imipenem-, gentamicin-, and minocycline-resistant strains at medical ward, chloramphenicol- and streptomycin-resistant strains at dental ward were isolated dominantly on each ward, MRSA isolates were classified to 39 types by drug-resistance patterns. The isolation frequencies of coagulase type II and type IV strains were 65.6% and 29.6%, respectively. At dental ward, the isolation frequency of coagulase type IV strains was higher than that of coagulase type II strains during 1990-1992. However, coagulase type II strains were isolated considerably more than type IV strains during 1993-1994. By MRSA-phage typing, MRSA isolates were grouped into 18 MRSA-phage types. One hundred and twenty five MRSA isolates were divided into 56 types by using drug-resistance patterns, coagulase typing, and MRSA-phage typing. It was considered that such classification in combination of three methods is useful to make decision of epidemic by the same MRSA strain.

Anti-Bacterial Agents↗

Identification of methicillin-resistant Staphylococcus aureus (MRSA): Comparison of a new molecular genetic test kit (GenoType MRSA) with standard diagnostic methods.

Results obtained from 188 isolates of staphylococci using standard diagnostic methods for identifying MRSA were compared with those achieved with a newly available molecular genetic test kit, the GenoType, Version 1, MRSA (Hain Lifescience GmbH, Nehren, Germany). The GenoType MRSA detects the mecA gene and, in addition, a highly specific sequence for Staphylococcus aureus (S. aureus) by polymerase chain reaction (PCR) and reverse hybridization. There was a 100% overall correlation between the results of conventional and molecular genetic testing. 143 isolates were tested positive for MRSA, 10 isolates were identified as oxacillin-sensitive Staphylococcus aureus strains (MSSA), and 35 isolates were coagulase-negative staphylococci of various species. However, five of the 143 MRSA strains yielded ambiguous results with the first line standard tests and therefore required additional testing leading to delay of definitive diagnosis. As expected, mecA could not only be detected in MRSA strains, but also in coagulase-negative staphylococci. The reliable identification as S. aureus from the same isolate is therefore an essential prerequisite for MRSA diagnosis. The GenoType MRSA fulfills this requirement by parallel detection of a S. aureus-specific sequence and the mecA gene. Molecular genetic testing with the GenoType MRSA kit needs much less time than conventional microbiological methods. Therefore genetic testing provides not only a considerable advantage with respect to reliability but also to speed.

Bacterial Proteins↗

Methicillin-resistant Staphylococcus aureus (MRSA) isolation from diabetic foot ulcers correlates with nasal MRSA carriage.

Methicillin-resistant Staphylococcus aureus is increasingly isolated from diabetic foot ulcers, and may be associated with an adverse prognosis. We have explored the relationship between MRSA isolation from foot ulcers and nasal MRSA carriage. Over a 12 month period, 65 consecutively attending patients with diabetic foot ulceration were recruited. Demographic information was collected, and the ulcer and nose swabbed bacteriologically using standard techniques. The patients were mean age 61 year, diabetes duration 14 year, and HbA1c 8.5%. There were 61% male and 85% with type 2 diabetes. Ulcers were neuropathic in 55%, ischaemic in 14% and neuroischaemic in 31%. MRSA was isolated from 12 (19%) ulcers, and 11 (17%) had nasal carriage. Of the MRSA positive ulcer patients 7/12 (58%) had nasal MRSA carriage, compared with 4/53 (8%) with MRSA negative ulcers (p<0.0003). We conclude that nasal MRSA carriage in diabetic patients is a significant risk factor for foot ulcer MRSA infection.

Adult↗

Active surveillance for methicillin-resistant Staphylococcus aureus (MRSA) decreases the incidence of MRSA bacteremia.

OBJECTIVES: To evaluate the influence of performance of active surveillance cultures for methicillin-resistant Staphylococcus aureus (MRSA) on the incidence of nosocomial MRSA bacteremia in an endemic hospital. DESIGN: Before-after trial. SETTING: A 700-bed hospital. PATIENTS: All patients admitted to the hospital who were at high risk for MRSA bacteremia. INTERVENTION: Performance of surveillance cultures for detection of MRSA were recommended for all patients at high risk, and contact isolation was implemented for patients with positive results of culture. Each MRSA-positive patient received one course of eradication treatment. We compared the total number of surveillance cultures, the percentage of surveillance cultures with positive results, and the number of MRSA bacteremia cases before the intervention (from January 2002 through February 2003) after the start of the intervention (from July 2003 through October 2004). RESULTS: The number of surveillance cultures performed increased from a mean of 272.57 cultures/month before the intervention to 865.83 cultures/month after the intervention. The percentage of surveillance cultures with positive results increased from 3.13% before to 5.22% after the intervention (P < .001). The mean number of MRSA bacteremia cases per month decreased from 3.6 cases before the intervention to 1.8 cases after the intervention (P < 0.001). CONCLUSIONS: Active surveillance culture is important for identifying hidden reservoirs of MRSA. Contact isolation can prevent new colonization and infection and lead to a significant reduction of morbidity and healthcare costs.

Bacteremia↗

[Analysis of methicillin-cephem resistant Staphylococcus aureus (MRSA) hospital infection and toxigenicity of MRSA].

MRSA infectious diseases were often observed in our ward including general, pediatric and neurosurgery during recent two years. Following items were investigated for analysing a prevalence of the infections; 1) the frequency of MRSA in Staphylococcus aureus isolates from clinical materials, 2) the monthly number of patients with MRSA infectious diseases, 3) the biologic types and the toxigenicity of MRSA isolates from clinical materials, nasal carriers and an environmental material in the ward. The results were as follows. 1) Methicillin-cephem resistant strain was determined in 204 of 247 Staphylococcus aureus isolates (83%). 2) Monthly registration showed a trend that an increased number of the patient in one unit was followed by an increase in other units. 3) Most of MRSA isolates were classified into type II coagulase and two kinds of strains were predominantly found in isolates from clinical materials by plasmid DNA analysis. Most of MRSA isolates had capabilities of producing type C enterotoxin and toxic shock syndrome toxin-1 (TSST-1). The results suggested that the frequent MRSA infectious diseases attributed to hospital infection. Since hospital infection of virulent MRSA may cause serious infectious diseases, much concern to inhibit the spread of this organism should be required.

Bacterial Toxins↗

A holistic approach to MRSA eradication in critically ill patients with MRSA pneumonia.

BACKGROUND: The number of Methicillin-resistant Staphylococcus aureus (MRSA) pneumonia cases is increasing in many European countries. In this observational study in one medical and three surgical ICUs multiple interventions for the treatment and eradication of nosocomial MRSA-pneumonia were used. PATIENTS AND METHODS: Twenty-one critically ill patients (age: 59 +/- 14 years, 15 males/6 females, 18 ventilator-associated, 3 nosocomial, clinical pulmonary infection score > 6 in all patients, APACHE II 18 +/- 5) were enrolled. The patients were treated with a 7-day course of iv linezolid (600 mg bid) plus rifampicin (600 mg bid), endotracheal vancomycin 100 mg qid, thrice daily mouth and throat washing with chlorhexidine 1% fluid and nasal mupirocin ointment, twice daily skin and hair washings with chlorhexidine gluconate 4% and tracheostomy (n = 8) wound care with povidone-iodine spray. Control samples (endotracheal secretions, nose, wound, and pharyngeal swabs) were taken 2, 3, 4, 7 days and 2 months thereafter. Multilobular pneumonia was seen in 16, pleural effusion in 12, and MRSA bacteremia in 4 patients. RESULTS: One patient died during the follow-up period due to cerebral bleeding. In the remaining 20 patients, pneumonia was clinically cured in all patients and all patients were free of MRSA after eradication. Six patients died due to myocardial infarction (n = 3), gram-negative septic shock (n = 2), herpes encephalitis (n = 1) > 7 days after eradication. No MRSA reinfection occurred during the control period. CONCLUSION: We conclude that in patients with MRSA pneumonia an approach using a 7-day course of intravenous linezolid plus rifampicin, intratracheal vancomycin, nasal mupirocin, cutaneous and oropharyngeal chlorhexidin plus povidone-iodine cures pneumonia and is effective for MRSA eradication.

Acetamides↗

Is methicillin-resistant Staphylococcus aureus (MRSA) contamination of ward-based computer terminals a surrogate marker for nosocomial MRSA transmission and handwashing compliance?

A survey of two acute district general hospitals (A and B) was undertaken to investigate the extent of methicillin-resistant Staphylococcus aureus (MRSA) contamination of ward-based computer terminals. Of 25 terminals examined, MRSA was identified in six (24%). Environmental contamination was of a low level. Five of the MRSA positive terminals were from hospital A which had a significantly higher rate of MRSA transmission compared to hospital B (1.02 vs. 0.49 new inpatient MRSA cases per 100 hospital admissions for 1999). MRSA containment and handwashing policies were similar at both hospitals, though only hospital B actively audited handwashing compliance and had a 44% higher rate of paper towel usage per hospital bed. Ward-based computer terminals pose a low risk of MRSA cross-infection. This risk can be further reduced if all staff wash their hands before and after patient contact.

Computer Terminals↗

A pilot study of an anti-MRSA bio-engineered lacteal complex (anti-MRSA BLC) in a murine septicemia model.

Methicillin-resistant Staphylococcus aureus (MRSA) is an important pathogen of humans and other animals, causing septicemia, abcessation, toxemia, and other infectious diseases. Refined bioengineered lacteal complex (BLC), made specifically against MRSA, is a novel complex of low molecular weight immunogenic and antimicrobial molecules. It was evaluated in vivo using a mouse model of MRSA-induced peritonitis. Intraperitoneal dosing of anti-MRSA BLC demonstrated a therapeutic effect (83% survival) against an intraperitoneal MRSA challenge that caused 100% mortality in untreated animals. Anti-MRSA BLC is a promising therapeutic modality for MRSA infection.

Animals↗

A study of the relationship between environmental contamination with methicillin-resistant Staphylococcus aureus (MRSA) and patients' acquisition of MRSA.

OBJECTIVE: The study aimed to examine the presence of methicillin-resistant Staphylococcus aureus (MRSA) in the environment and its relationship to patients' acquisition of MRSA. DESIGN: A prospective study was conducted in a 9-bed intensive care unit for 14 months. At every environmental screening, samples were obtained from the same 4 sites in each bed space. Patients were screened at admission and then 3 times weekly. All environmental and patient strains were typed using pulsed-field gel electrophoresis. RESULTS: MRSA was isolated from the environment at every environmental screening, when both small and large numbers of patients were colonized. Detailed epidemiological typing of 250 environmental and 139 patient isolates revealed 14 different pulsed-field gel electrophoresis profiles, with variants of EMRSA-15 being the predominant type. On only 20 (35.7%) of 56 occasions were the strains isolated from the patients and the strains isolated from their immediate environment indistinguishable. There was strong evidence to suggest that 3 of 26 patients who acquired MRSA while in the intensive care unit acquired MRSA from the environment. CONCLUSIONS: This study reveals widespread contamination of the hospital environment with MRSA, highlights the complexities of the problem of contamination, and confirms the need for more-effective cleaning of the hospital environment to eliminate MRSA.

Cross Infection↗

Selective screening of carriers for control of methicillin-resistant Staphylococcus aureus (MRSA) in high-risk hospital areas with a high level of endemic MRSA.

Screening for methicillin-resistant Staphylococcus aureus (MRSA) carriage in patients at risk was evaluated as part of a control program in a 26-bed medical intensive care unit (ICU) of a university hospital with a high level of endemic MRSA. Control measures included isolation and barrier precautions, skin decolonization with chlorhexidine of patients from whom MRSA was recovered, and mupirocin treatment of nasal carriers of MRSA. Of 3,686 patients admitted during a 4-year period, 44% were screened, which occurred during admission for 38%; MRSA was recovered from 293 patients (8%). There were 150 imported cases and 143 ICU-acquired cases, of which 51% and 45%, respectively, were first identified through screening. Nasal swab cultures identified 84% of MRSA carriers. The incidence of all ICU-acquired cases and of acquired colonization or infection decreased from 5.8% and 5.6% to 2.6% and 1.4% (P = .002 and P < .001), respectively, whereas that of imported cases remained unchanged (range, 3.8% to 4.3%; P = .8). Selective screening for nasal carriage during admission to high-risk areas may contribute to identification of a substantial proportion of cases of MRSA and to early implementation of effective control measures.

Carrier State↗

[Nosocomial infections due to methicillin-resistant S. aureus (MRSA) at the Kagoshima University Hospital (1). Coagulase typing of MRSA].

Nosocomial infection due to MRSA at the Kagoshima University Hospital and their coagulase typing were examined using S. aureus (349 strains) clinically isolated in 1989. The results were as follows: 1) S. aureus consisted of 43.6% of MRSA and 56.7% of Methicillin-sensitive S. aureus (MSSA). 2) MRSAs were recovered most frequently from the specimens from the respiratory tract (47.8%). 3) The isolation of MRSA gradually increased in frequency from January to August; however, that of MSSA did not show a similar tendency. 4) The isolation of MRSA was higher in frequency in the surgical wards, the ICU and the pediatric ward. 5) When classified into 8 coagulase types, MRSAs (133 strains) consisted of only 3 types (54.1% of type II, 32.3% of type VII, and 12.0% of type IV), whereas MSSAs contained all coagulase types. As compared with the results of coagulase typing at other institutions, the incidence of type VII was much more frequent at our hospital. 6) A few coagulase types of MRSA appeared in each ward. Also, type II MRSA strains increased in June and July, and type VII MRSA increased in August. However, MSSA strains did not show any similar tendency.

Bacterial Typing Techniques↗

A Panton-Valentine leucocidin (PVL)-positive community-acquired methicillin-resistant Staphylococcus aureus (MRSA) strain, another such strain carrying a multiple-drug resistance plasmid, and other more-typical PVL-negative MRSA strains found in Japan.

Community-acquired methicillin-resistant Staphylococcus aureus (CA-MRSA) was collected from children with bullous impetigo in 2003 and 2004. One strain collected in 2003 was Panton-Valentine leucocidin (PVL) positive. In 2004, a multiple-drug-resistant PVL(+) CA-MRSA strain was isolated from an athlete with a cutaneous abscess. These strains were analyzed by multilocus sequence typing, spa typing, agr typing, coagulase typing, staphylococcal cassette chromosome mec (SCCmec) typing, PCR assay for 30 virulence genes, drug susceptibility testing, pulsed-field gel electrophoresis, and for plasmids. The two Japanese PVL(+) CA-MRSA strains belonged to the globally extant ("pandemic") sequence type 30 (ST30) with SCCmec IV. A transmissible, multiple-drug resistance plasmid emerged in such ST30 strains. The PVL(-) CA-MRSA strains ("domestic" CA-MRSA) accumulated for bullous impetigo, exhibiting new genotypes. Hospital-acquired MRSA of ST91 (but not pandemic ST5) shared common features with the PVL(-) CA-MRSA strain.

Adolescent↗