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PubMed1996

Increased incidence of beta-lactamase-plasmid negative, high level methicillin-resistant Staphylococcus aureus (MRSA).

Recently isolated strains of methicillin-resistant Staphylococcus aureus (MRSA) have high levels of resistance to the agent and produce beta-lactamase less frequently than methicillin-susceptible strains (MSSA). This phenomenon has been observed in Japan. The majority of MSSA strains (26 of 30) isolated in 1992 produced beta-lactamase while only 18 of 31 and 25 of 67 MRSA strains, isolated in 1991 and in 1992 respectively, produced the enzyme. We analyzed the beta-lactamase gene (blaZ) in 30 strains each of MRSA and MSSA isolated from our hospital using the polymerase chain reaction. We found that 28 MSSA strains but only 14 MRSA strains possessed the gene. In addition, the present study indicates that many recently isolated MRSA strains, which lacked blaZ gene and were negative for beta-lactamase, consistently produced coagulase of type II (coagulase typing is a marker of epidemiology for Staphylococcus aureus). These beta-lactamase negative, type II coagulase producing and highly methicillin-resistant MRSA strains are considered to have an increased ability to successfully colonize individuals and an increased epidemic potential, probably because of the saving of the energy otherwise expended in beta-lactamase production and of the loss of beta-lactamase plasmid coding the mecA gene repressor, resulting in constitutive PBP2' production. These factors may contribute to the wide spread of these strains of MRSA in a nosocomial environment.

Humans↗
PubMed1990

[Four cases of airway infections caused by MRSA (methicillin resistant Staphylococcus aureus)].

Currently, infections caused by MRSA (methicillin-resistant Staphylococcus aureus) pose a great problem clinically. We present 4 patients with MRSA infections experienced by us. In these patients the infection was localized in the trachea and main bronchus. The first patient was a 62-year-old man. After undergoing operation for early gastric cancer, he had septic shock and was admitted to our center. The second was a 60-year-old man. After he underwent operation for advanced gastric carcinoma at another hospital septicemia developed due to suture failure and he was admitted to our center. The third was a 38-year-old woman who was admitted to our center because of grades II degrees-III degrees burns on 75 to 80% of her body surface area. The fourth was a 60-year-old man who was admitted to our center because of rupture of an aneurysm of the abdominal aorta. It is assumed that MRSA has quite different characteristics from the usual MSSA (methicillin-sensitive Staphylococcus aureus) in that it produces a new penicillin-bound protein (PBP-2') within cells. Thus, from the fiberoptic bronchoscopy findings of our own cases it is considered that there may be cases in which the observed lesion is localized in the central airway alone, without involvement of the segmental bronchi. We believe it necessary to take some prompt measures under a suspicion of airway infection caused by MRSA in the following cases: (1) compromised hosts under tracheal intubation, (2) patients who are under treatment with second or third generation cephalosporins, and (3) patients with production of bloody sputum, and (4) endotoxin-positive patients.

Adult↗
PubMedDate not supplied

[State of methicillin resistant Staphylococcus aureus in the Hospital of Navarre (2000-2002)].

BACKGROUND: The aim of the present paper was to determine the prevalence and characteristics shown by isolations of Methicillin Resistant Staphylococcus Aureus, isolated in our Microbiology Service. METHODS: Retrospective study, covering the years 2000, 2001 and 2002. Analysis was made of the origin of the infection (nosocomial or non-nosocomial), the unit of origin in the event of nosocomial origin, anatomical localisation of the sample, and pattern of antibiotic sensitivity. RESULTS: The isolations of Methicillin Resistant Staphylococcus aureus accounted for 7.88% of the Staphylococcus aureus isolated. Less than half of the strains (44.87%) had a nosocomial origin and were most often isolated in the exudates of wounds. With respect to the pattern of resistance, there was some 50% of resistance to erythromycin, some 43.60% to clindamycine and some 21.79% to mupirocin. CONCLUSIONS: The prevalence and resistance pattern in vitro of the isolations of Methicillin Resistant Staphylococcus Aureus in our hospital are lower than that published in other areas of Spain.

Anti-Bacterial Agents↗
PubMed1995

Molecular epidemiology of a multiple strain outbreak of methicillin-resistant Staphylococcus aureus amongst patients and staff.

Since methicillin-resistant Staphylococcus aureus (MRSA) isolates are not endemic in our hospital, which is a tertiary referral centre, the finding of 13 MRSA isolates from 12 patients associated with an acute vascular surgery ward between October 1993 and December 1993 prompted further epidemiological and laboratory investigations. Two strains were distinguished by antibiogram and phage-typing. One strain, resembling EMRSA-16, colonized six patients and was probably introduced from another hospital in the Oxford Region. Five other patients were colonized by a second strain, gentamicin-resistant and non-typable by phage-typing, probably introduced into the hospital 12 months previously by a patient from Nairobi, Kenya. A 12th patient was colonized by both strains simultaneously. Of 46 staff members screened three were colonized--one by an EMRSA-16 strain, a second by the gentamicin-resistant 'Nairobi'-strain and a third member carried yet a further distinct MRSA strain. The healthcare worker colonized by the 'Nairobi'-strain had been carrying the isolate 12 months previously and was the likely source of this strain. These isolates were also characterized by the repetitive extragenic palindromic-polymerase chain reaction (REP-PCR), a novel PCR-based methodology which has not been previously used in characterizing Staphylococcus aureus in an outbreak. This method corroborated the strain classifications provided by the traditional methods, confirming that there had been spread of two strains simultaneously. Our study demonstrates that multiple strains of MRSA may circulate amongst patients and staff during an outbreak, patients may be colonized by more than one strain simultaneously and long-term staff carriage (> 12 months) may be an important source of colonization in patients. REP-PCR is a rapid and effective molecular typing method for MRSA.

Bacterial Typing Techniques↗
PubMed2001

RNAIII inhibiting peptide (RIP), a global inhibitor of Staphylococcus aureus pathogenesis: structure and function analysis.

Staphylococcus aureus are gram-positive bacteria that can cause serious diseases in humans and animals. S. aureus infections can be prevented by the heptapeptide RNAIII inhibiting peptide (RIP). RIP was originally isolated from culture supernatants of coagulase negative staphylococci presumed to be S. xylosus. The sequence of RIP was identified as YSPXTNF. Native RIP and its synthetic analogue YSPWTNF have been shown to be effective inhibitors of diseases caused by various strains of S. aureus, including, cellulitis, keratitis, septic arthritis, osteomylitis and mastitis. RIP is therefore considered to be a global inhibitor of S. aureus. We show here that: 1) the amide form of RIP (YSPWTNF-NH2) is highly stable and is therefore the one recommended for use. 2) RIP inhibits S. aureus pathogenesis by inhibiting the synthesis of both agr transcripts RNAII and RNAIII. 3) Although RIP inhibits agr, it also reduces bacterial adherence to mammalian cells and to plastic (tested on HEp2 cells and on polystyrene by fluorescence and atomic force microscopy), suggesting that RIP can be used safely as a therapeutic molecule. 4) RIP derivatives were designed and tested for their ability to inhibit RNAIII in vitro and cellulitis in vivo. Not all peptides that inhibited RNAIII also inhibited an infection in vivo, indicating that studies must be carried out in vivo before considering a peptide to be of therapeutic potential. 5) The RIP derivative containing Lysine and Isoleucine at positions 2 and 4, respectively, inhibited S. aureus infections in vivo (tested on cellulitis), suggesting that both RIP YSPWTNF and its derivative YKPITNF are effective inhibitors of infections caused by S. aureus.

Bacterial Proteins↗
PubMed2005

[Vancomycin-resistant Staphylococcus aureus].

The evolution and molecular mechanisms of vancomycin resistance in Staphylococcus aureus were reviewed. Case reports and research studies on biochemestry, electron microscopy and molecular biology of Staphylococcus aureus were selected from Medline database and summarized in the following review. After almost 40 years of successful treatment of S. aureus with vancomycin, several cases of clinical failures have been reported (since 1997). S. aureus strains have appeared with intermediate susceptibility (MIC 8-16 microg/ml), as well as strains with heterogeneous resistance (global MIC < or =4 microg/ml), but with subpopulations of intermediate susceptibility. In these cases, resistance is mediated by cell wall thickening with reduced cross linking. This traps the antibiotic before it reaches its major target, the murein monomers in the cell membrane. In 2002, a total vancomycin resistant strain (MIC > or =32 microg/ml) was reported with vanA genes from Enterococcus spp. These genes induce the change of D-Ala-D-Ala terminus for D-Ala-D-lactate in the cell wall precursors, leading to loss of affinity for glycopeptides. Vancomycin resistance in S. aureus has appeared; it is mediated by cell wall modifications that trap the antibiotic before it reaches its action site. In strains with total resistance, Enterococcus spp. genes have been acquired that lead to modification of the glycopeptide target.

Anti-Bacterial Agents↗
PubMed1997

A case of superantigen-related glomerulonephritis after methicillin-resistant Staphylococcus aureus (MRSA) infection.

A case in which the enterotoxins of Staphylococcus aureus may have served as bacterial superantigens is presented. This 71-year-old man developed proteinuria and renal dysfunction after contacting pneumonia caused by methicillin-resistant Staphylococcus aureus (MRSA), coagulase type II. The infection occurred after surgery for recurrent lung cancer. Staphylococcus enterotoxins B, C, and TSST-1 were detected from the bacillus. Ten days after the onset of pneumonia, proteinuria was noted; urinary protein was as high as 1.8 g/day. The serum creatinine was elevated from 1.0 mg/dl to 3.7 mg/dl. Several immunological reactions were detected; the serum levels of IgG and IgA were increased, and the selective usage of T-cell receptor V beta (TCRV beta) was observed. Serum levels of IL-1 beta, IL-2, IL-6, IL-8, IL-12, and tumor necrosis factor alpha (TNF alpha) were also elevated. Examination of the renal biopsy specimen by light microscopy showed minor to mild mesangial proliferative glomerulonephritis. Immunofluorescence microscopy demonstrated the deposition of IgG, IgA, and C3, mainly along the capillary walls. Electron microscopy revealed electron dense deposits, mainly in the subepithelial areas, and injury to the glomerular basement membrane. When the pneumonia improved following antibiotic therapy, the renal function also improved, and proteinuria decreased. The levels of immunoglobulins and the usage of TCRV beta also decreased. Because staphylococcus enterotoxins act as superantigens, we believe this to be a typical case of superantigen-related glomerulonephritis.

Aged↗
PubMed2026

The spatial and temporal distribution of Staphylococcus aureus along a tropical Hawaiian watershed.

Staphylococcus aureus is a leading cause of community-acquired skin and soft-tissue infections worldwide. One major route of exposure is recreating in marine waters, but knowledge is limited regarding the drivers of S. aureus in surface waters that discharge into marine environments. This study explores spatial and temporal distributions of S. aureus, including antimicrobial-resistant and virulence genes, using both culture-dependent and molecular techniques across a tropical Hawaiian watershed with a gradient of human influence. Negative binomial generalized linear mixed models revealed that the interaction between spatial and temporal factors was the strongest predictor of S. aureus and associated genes. Cultured S. aureus was highest at mid-watershed sites in summer, which included a popular swimming hole, suggesting human shedding as a significant source. Molecular detection of S. aureus (femA gene) yielded concentrations two orders of magnitude higher than cultured concentrations and peaked at estuarine sites with the greatest nutrients and water residence times. In the winter at upstream sites with no public access, staphylococci antibiotic-resistant (mecA) and S. aureus virulence gene (etb) were elevated, indicating highly pathogenic S. aureus strains in surface waters may originate from zoonotic sources. Our findings indicate that human and zoonotic sources contribute antibiotic-resistant and virulent S. aureus to watersheds, with streams facilitating environmental transmission to marine waters. This watershed-scale assessment enables the prediction of spatial and temporal conditions associated with elevated S. aureus concentrations, thereby reducing exposure and infections.

Staphylococcus aureus↗
PubMed2003

Staphylococcus aureus meningitis: experience with cefuroxime treatment during a 16 year period in a Danish region.

Staphylococcus aureus is a rare cause of bacterial meningitis and there is no consensus on antibiotic treatment. Nafcillin is a common choice in countries where it is approved and marketed. High-dose cefuroxime has been the systemic treatment used in the study region, and a retrospective record review was conducted to determine its clinical efficacy. Cases of bacterial meningitis during 1984-1999 in the County of North Jutland, Denmark (approx. 490000 inhabitants), were identified in a regional bacteriology register. Inclusion of a case required either growth of S. aureus from > or = 2 specimens of cerebrospinal fluid (CSF), 1 positive CSF specimen with a CSF leucocyte count > 10(8)/l or 1 positive CSF specimen with a concurrent positive blood culture. A diagnosis of brain abscess required growth of S. aureus from aspirated pus. Staphylococcus aureus meningitis was confirmed in 45 patients, and 5 additional patients had a brain abscess. 44 cases were nosocomial (mortality 16%) and 6 were community acquired (mortality 83%). None of the isolates was methicillin resistant and 6 were penicillin susceptible. Intraventricular antibiotic treatment was given to 28 patients, systemic therapy included cefuroxime in 32 patients (64%) as either a primary or secondary choice, 6 (12%) were treated with penicillin G, 10 (20%) with penicillinase-resistant penicillin and 2 (4%) with cephalothin. Among 31 nosocomial cases treated systemically with cefuroxime the mortality was 10% (95% exact confidence limits 2-26%). In conclusion, cefuroxime seems to be a valid choice for S. aureus meningitis in the nosocomial setting.

Adolescent↗
PubMed1995

Multicenter evaluation of arbitrarily primed PCR for typing of Staphylococcus aureus strains.

Fifty-nine isolates of Staphylococcus aureus and a single strain of Staphylococcus intermedius were typed by arbitrarily primed PCR (AP-PCR). To study reproducibility and discriminatory abilities, AP-PCR was carried out in seven laboratories with a standardized amplification protocol, template DNA isolated in a single institution, and a common set of three primers with different resolving powers. The 60 strains could be divided into 16 to 30 different genetic types, depending on the laboratory. This difference in resolution was due to differences in technical procedures (as shown by the deliberate introduction of experimental variables) and/or the interpretation of the DNA fingerprints. However, this did not hamper the epidemiologically correct clustering of related strains. The average number of different genotypes identified exceeded those of the more traditional typing strategies (F. C. Tenover, R. Arbeit, G. Archer, J. Biddle, S. Byrne, R. Goering, G. Hancock, G. A. Hebert, B. Hill, R. Hollis, W. R. Jarvis, B. Kreiswirth, W. Eisner, J. Maslow, L. K. McDougal, J. M. Miller, M. Mulligan, and M. A. Pfaller, J. Clin. Microbiol. 32:407-415, 1994). Comparison of AP-PCR with pulsed-field gel electrophoresis (PFGE) indicated the existence of strains with constant PFGE types but variable AP-PCR types. The reverse (constant AP-PCR and variable PFGE patterns) was also observed. This indicates additional resolution for combined analyses. It is concluded that AP-PCR is well suited for genetic analysis and monitoring of nosocomial spreading of staphylococci. The interlaboratory reproducibility of DNA-banding patterns and the intralaboratory standardization need improvement.

Bacterial Typing Techniques↗
PubMed1988

Methicillin-resistant Staphylococcus aureus at Tygerberg Hospital.

During 1985 Staphylococcus aureus was isolated from blood cultures of 74 patients at Tygerberg Hospital who were suffering from serious illness compatible with systemic spread of the organism. Twenty-six isolates (35%) were community-acquired and none were methicillin-resistant, while 48 were hospital-acquired of which 23 (48%) were methicillin-resistant. Methicillin resistance appears to be a problem confined to hospital isolates of S. aureus.

Cross Infection↗
PubMed2000

Molecular epidemiology of methicillin-resistant Staphylococcus aureus in Finland.

This study reports the recent trends in the occurrence of methicillin-resistant Staphylococcus aureus in Finland, with special focus on characterization of the strains linked to interhospital epidemics and local outbreaks. Between 1981 and 1997, the annual number of methicillin-resistant Staphylococcus aureus isolations ranged from 89 to 272. Of all blood isolates of Staphylococcus aureus reported to the National Infectious Disease Register during the period 1995-97 (n = 2049), only six were resistant to methicillin. Between 1992 and 1997, typing analysis by various methods (i.e., antibiogram, phage typing, ribotyping, and pulsed-field gel electrophoresis) identified 18 different strains capable of causing intrahospital outbreaks or interhospital epidemics. These 18 strains were separated into 13 different ribotypes and 14 major pulsed-field gel electrophoresis types. Multiresistance was investigated as a possible marker for epidemicity. Eight of the ten interhospitally spread strains were multiresistant compared to only three of the eight intrahospitally spread outbreak strains. More than one-third of the epidemic and local outbreak strains were suspected to be of foreign origin. The majority (6 of 10) of the epidemics were localized in southern and western Finland, and the largest epidemic, which occurred in the Helsinki metropolitan area, involved over 200 persons. Thus far, the epidemics have remained primarily intracity problems, and only two strains have become endemic.

Anti-Bacterial Agents↗
PubMed2001

[Research of drug resistance and detection of methicillin-resistant Staphylococcus aureus in chronic maxillary sinusitis].

OBJECTIVE: To investigate the detection method of methicillin-resistant staphylococcus aureus (MRSA) in chronic maxillary sinusitis and the situation of drug resistance to some common antibiotics. METHOD: Using multiplex polymerase chain reaction technique to detect the drug resistant gene (mecA) of MRSA and specific gene (femA) of staphylococcus aureus at the same time. Drug resistant tests were performed with disk diffusion (K-B) method. RESULT: femA is a specific gene of staphylococcus aureus, the detective ratio of mecA in MRSA is 96.2% (51/53). Vancomycin is the only antibiotic which is sensitive to MRSA, while others are not. CONCLUSION: MRSA can be rapidly and specifically identified with multiplex PCR. There are drug resistance to many antibiotic drugs for MRSA.

Adolescent↗
PubMed1997

Comparative performances of six agglutination kits assessed by using typical and atypical strains of Staphylococcus aureus.

Six commercial agglutination tests designed for the identification of Staphylococcus aureus were compared by using a strain collection which included 512 staphylococci representing 33 species (318 isolates of Staphylococcus aureus [including 144 oxacillin resistant], 46 S. epidermidis isolates, 15 S. haemolyticus isolates, 12 S. saprophyticus isolates, 29 S. schleiferi isolates, 30 S. lugdunensis isolates, and 62 other coagulase-negative staphylococci). This group also included a proportion of strains with unusual phenotypes (e.g., 19 coagulase-negative S. aureus isolates, 26 clumping factor-negative S. aureus isolates, and 4 S. aureus isolates each with a double deficiency). The overall sensitivity for identification of typical and atypical S. aureus was high with the Staphaurex Plus test (Murex Biotech) (99.7%), the Pastorex Staph Plus test (Sanofi Diagnostics Pasteur) (99.7%), and the Slidex Staph Plus test (bioMérieux) (100%). The overall rate of specificity was affected by the unusual inclusion in this study of a high proportion of non-S. aureus species, such as S. lugdunensis and S. schleiferi, which express a clumping factor and therefore produce a positive result with the agglutination tests.

Agglutination Tests↗
PubMed2000

Intracellular Staphylococcus aureus induces apoptosis in mouse osteoblasts.

Staphylococcus aureus invades osteoblasts and is the primary cause of osteomyelitis. This study examined the ability of S. aureus to induce apoptosis in a mouse osteoblast cell line. The presence of intracellular S. aureus was demonstrated by transmission electron microscopy. Light microscopy was utilized to examine morphological changes in the osteoblasts following killing of extracellular bacteria. Cell rounding was observed, and dark centers due to condensation of chromatin were noted in cells in infected osteoblast cultures. DNA was isolated from infected osteoblast cultures, and electrophoresis revealed the laddering effect characteristic of cells undergoing apoptosis. Additionally, an in situ cell death detection assay was utilized to label apoptosis-induced DNA strand breaks. Apoptotic nuclei were present, providing further evidence that S. aureus induces apoptosis in osteoblasts.

3T3 Cells↗
PubMed1989

Generation and characterization of monoclonal antibodies against Staphylococcus aureus thermonuclease.

Monoclonal antibodies (MAbs) against Staphylococcus aureus thermonuclease (TN) were raised by immunizing BALB/c mice with a commercial TN preparation. Six monoclones were generated producing MAbs specific for S. aureus TN as tested in Western blots and ELISA. They all combined with a 17 kD and a 21 kD protein, respectively, both of which showed DNase activity. All MAbs were of IgG1 isotype with kappa light chain. Competition ELISA showed that five of the MAbs recognized a total of three different binding sites of TN, designated I, II and III, respectively. Only the anti-site II MAbs inhibited the DNase activity. A MAb-based sandwich ELISA showed a lower detection limit for TN of approximately 0.5 ng/ml protein. Only S. aureus strains (culture supernatants) showed positive ELISA (31 positive/31 tested), although other tested gram positive cocci produced thermostable nucleases. The MAbs have potentials as reagents for rapid and specific detection of S. aureus.

Animals↗
PubMed1965

SENSITIVITY OF MIXED POPULATIONS OF STAPHYLOCOCCUS AUREUS AND ESCHERICHIA COLI TO MERCURIALS.

Staphylococcus aureus was found to have a higher resistance to merbromin and mercuric chloride in the presence of Escherichia coli. The protective effect of the gram-negative organism on S. aureus was due to the production of extracellular glutathione and hydrogen sulfide and to an unequal distribution of the inhibitor between the two species. S. aureus did not significantly influence the resistance of E. coli to mercurials.

Centrifugation↗
PubMedDate not supplied

The burden of Staphylococcus aureus infections on hospitals in the United States: an analysis of the 2000 and 2001 Nationwide Inpatient Sample Database.

BACKGROUND: Previous studies have investigated the impact of Staphylococcus aureus infections on individual hospitals, but to date, no study using nationally representative data has estimated this burden. METHODS: This is a retrospective analysis of the 2000 and 2001 editions of the Agency for Healthcare Research and Quality's Nationwide Inpatient Sample database, which represents a stratified 20% sample of hospitals in the United States. All inpatient discharge data from 994 hospitals in 28 states during 2000 and from 986 hospitals in 33 states during 2001, representing approximately 14 million inpatient stays, were analyzed to determine the association of S aureus infections with length of stay, total charges, and in-hospital mortality. RESULTS: Staphylococcus aureus infection was reported as a discharge diagnosis for 0.8% of all hospital inpatients, or 292 045 stays per year. Inpatients with S aureus infection had, on average, 3 times the length of hospital stay (14.3 vs 4.5 days; P<.001), 3 times the total charges (48,824 US dollars vs 14,141 US dollars; P<.001), and 5 times the risk of in-hospital death (11.2% vs 2.3%; P<.001) than inpatients without this infection. Even when controlling for hospital fixed effects and for patient differences in diagnosis-related groups, age, sex, race, and comorbidities, the differences in mean length of stay, total charges, and mortality were significantly higher for hospitalizations associated with S aureus. CONCLUSIONS: Staphylococcus aureus infections represent a considerable burden to US hospitals, particularly among high-risk patient populations. The potential benefits to hospitals in terms of reduced use of resources and costs as well as improved outcomes from preventing S aureus infections are significant.

Age Factors↗