SEARCH · PubMed Health

Results for “Staphylococcus”

Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 235 records · Page 13Linked to original sources

PubMed2001

Staphylococcus aureus bacteriuria and surgical site infections by methicillin-resistant Staphylococcus aureus.

Surgical site infection (SSI) remains an important cause of morbidity among hospitalized patients. We reviewed 421 patients who underwent open urological operations between January 1993 and December 1997 in our institute. Group I consisted of 259 patients who received uncontrolled antimicrobial prophylaxis (AMP) between 1993 and 1995. Group II consisted of 162 patients who received controlled AMP between 1996 and 1997. In group II, penicillins or first to second-generation cephalosporins was used and the duration of use for these agents regulated according to the wound class of each operation. The operations with clean wounds showed the lowest rate of SSI in both groups; the operations with contaminated wounds showed the highest rate of SSI (32.0% in group I and 33.3% in group II). There was no significant difference in the total rates of SSI between the two groups (P=0.216). The most frequently isolated bacterial species was methicillin-resistant Staphylococcus aureus (MRSA), isolated in 73.3% of the cases in group I and in 93.3% in group II. There was no significant difference in the incidence of MRSA isolation between the two groups (P=0.114). The controlled AMP could not lower the incidence of MRSA-induced SSIs. In SSI patients, 22.7% of group I and 35.7% in group II, had MRSA bacteriuria before operation. The prohibition of third-generation cephalosporins and shorter duration of AMP did not reduce the incidence of SSI induced by MRSA because MRSA was not the emerging microorganism but rather a resident in the urological ward. On the other hand, the total incidence of SSI did not increase after regulation of AMP. This finding suggests that older antibacterial agents can prevent infection, except those caused by resistant microorganisms such as MRSA. The effective counter-measure for the prevention of MRSA-induced SSI is needed.

Anti-Infective Agents, Urinary↗

PubMed1999

Emergence of vancomycin resistance in Staphylococcus aureus. Glycopeptide-Intermediate Staphylococcus aureus Working Group.

BACKGROUND: Since the emergence of methicillin-resistant Staphylococcus aureus, the glycopeptide vancomycin has been the only uniformly effective treatment for staphylococcal infections. In 1997, two infections due to S. aureus with reduced susceptibility to vancomycin were identified in the United States. METHODS: We investigated the two patients with infections due to S. aureus with intermediate resistance to glycopeptides, as defined by a minimal inhibitory concentration of vancomycin of 8 to 16 microg per milliliter. To assess the carriage and transmission of these strains of S. aureus, we cultured samples from the patients and their contacts and evaluated the isolates. RESULTS: The first patient was a 59-year-old man in Michigan with diabetes mellitus and chronic renal failure. Peritonitis due to S. aureus with intermediate resistance to glycopeptides developed after 18 weeks of vancomycin treatment for recurrent methicillin-resistant S. aureus peritonitis associated with dialysis. The removal of the peritoneal catheter plus treatment with rifampin and trimethoprim-sulfamethoxazole eradicated the infection. The second patient was a 66-year-old man with diabetes in New Jersey. A bloodstream infection due to S. aureus with intermediate resistance to glycopeptides developed after 18 weeks of vancomycin treatment for recurrent methicillin-resistant S. aureus bacteremia. This infection was eradicated with vancomycin, gentamicin, and rifampin. Both patients died. The glycopeptide-intermediate S. aureus isolates differed by two bands on pulsed-field gel electrophoresis. On electron microscopy, the isolates from the infected patients had thicker extracellular matrixes than control methicillin-resistant S. aureus isolates. No carriage was documented among 177 contacts of the two patients. CONCLUSIONS: The emergence of S. aureus with intermediate resistance to glycopeptides emphasizes the importance of the prudent use of antibiotics, the laboratory capacity to identify resistant strains, and the use of infection-control precautions to prevent transmission.

Aged↗

PubMed2003

Susceptibility of skin and soft-tissue isolates of Staphylococcus aureus and Streptococcus pyogenes to topical antibiotics: indications of clonal spread of fusidic acid-resistant Staphylococcus aureus.

Staphylococcus aureus (SA) isolates (n = 255) from outpatients with skin and soft-tissue infections were collected in 3 different areas in Norway. Group A streptococci (GAS, n = 68) were isolated from skin or pharyngotonsillar specimens from outpatients. Minimum inhibitory concentrations (MIC) of bacitracin, fusidic acid and mupirocin were tested using the E-test. Pulsed field gel electrophoresis (PFGE) patterns of fusidic acid-sensitive (FusS) and -resistant (FusR) SA were compared. All GAS isolates showed MIC of bacitracin of < or = 1.0 mg/l, of mupirocin of < or = 0.125 mg/l and of fusidic acid 1.0-4.0 mg/l. All the SA showed MIC of mupirocin < or = 0.5 mg/l and of bacitracin of > or = 2.0 mg/l, 91% with MIC > or = 16 mg/l. FusR was shown by 32.5% of the SA strains with similar prevalence rates in 3 different geographical areas of Norway. One particular PFGE pattern (type 1) was shown by 76% of the FusR SA. SA of type 1 belonged to phage group II and produced exfoliative toxins. Thus, the results demonstrated a high prevalence of FusR among SA causing skin infections and that this was mainly due to dissemination of clonally related FusR SA.

Administration, Topical↗

PubMed2000

Nosocomial methicillin-resistant Staphylococcus aureus bacteremia: is it any worse than nosocomial methicillin-sensitive Staphylococcus aureus bacteremia?

OBJECTIVE: To determine the comparative virulence of methicillin-resistant Staphylococcus aureus (MRSA) and methicillin-sensitive S aureus (MSSA) by consideration of predisposing factors and outcomes in patients infected with these organisms in the healthcare setting. DESIGN: Analysis of an historical cohort of 504 bacteremic patients (316 MSSA and 188 MRSA), examining factors associated with mortality. SETTING: A 916-bed, university-affiliated, tertiary referral hospital. RESULTS: Risk factors for the development of MRSA include male gender, admission due to trauma, immunosuppression, presence of a central vascular line or an indwelling urinary catheter, and a past history of MRSA infection. Overall mortality was 22%. Death due to bacteremia was significantly greater in the MRSA group (risk ratio, 1.68; P<.05), although these patients were not found to be more likely to die due to underlying disease during treatment of bacteremia. In those patients who recovered from bacteremia, no significant differences for the outcome of death could be determined between the MRSA and MSSA groups. CONCLUSIONS: There is a general consensus in the published literature that MRSA bacteremia is more likely to be associated with death, and we confirm this conclusion. However, in contrast to other studies, our MRSA cohort does not appear to be more at risk of death due to underlying disease during treatment for bacteremia. Similarly, the general consensus that MRSA patients have an increased overall mortality was not confirmed in our study. Differences in comorbidities of patients may provide some explanation of these conflicting results, while an alternate explanation is that MRSA strains are more virulent than MSSA in some centers. Perhaps the most plausible explanation is that treatment is provided earlier and in a more aggressive fashion in some centers, leading to an overall lower mortality rate in all staphylococcal bacteremias in these institutions.

Australia↗

PubMed1983

Vancomycin treatment of bacteremia caused by oxacillin-resistant Staphylococcus aureus: comparison with beta-lactam antibiotic treatment of bacteremia caused by oxacillin-sensitive Staphylococcus aureus.

The epidemiology and therapy of 29 episodes of bacteremia caused by oxacillin- and aminoglycoside-resistant Staphylococcus aureus (OARSA) were compared with 29 episodes of bacteremia due to oxacillin-sensitive S. aureus (OSSA) that occurred during a 36-month period. Patients with bacteremia due to OSSA were younger (P less than 0.05) and were admitted more frequently with acute traumatic injury (P less than 0.01). The overall survival rate one month after persistent bacteremia was 74% for patients with OARSA bacteremia treated with vancomycin compared with 70% for patients with OSSA bacteremia treated with a beta-lactam antibiotic. The results indicate that vancomycin is an effective antibiotic for the treatment of bacteremia caused by OARSA and suggest that its effectiveness is comparable to that of beta-lactam antibiotic treatment of bacteremia due to OSSA.

Anti-Bacterial Agents↗

PubMed1983

Frequency of resistance to trimethoprim among isolates of Staphylococcus epidermidis and Staphylococcus saprophyticus.

Four hundred and forty-nine strains of staphylococci, 386 Staphylococcus epidermidis and 63 Staph. saprophyticus were tested by MIC and disc for susceptibility to trimethoprim. About 30% of clinically significant strains of Staph. epidermidis were resistant to trimethoprim; this fell to 12.6% in strains from normal flora. The frequency of resistance among clinically significant strains did not alter from 1976 to 1980. Strains of Staph. saprophyticus were uniformly sensitive to trimethoprim.

Culture Media↗

PubMed1999

Head-injured patients who are nasal carriers of Staphylococcus aureus are at high risk for Staphylococcus aureus pneumonia.

OBJECTIVE: To determine if head-injured patients with premorbid nasal colonization with Staphylococcus aureus are at increased risk for S. aureus infection. DESIGN: Patients admitted over a 2-yr period were enrolled if they met the following criteria: Injury Severity Score > or = 9, intensive care unit (ICU) admission, hospitalization in another hospital < 24 hrs, no recent use of antibiotics. SETTING: Acute care trauma facility. PATIENTS: Any patient sustaining acute, blunt, or penetrating injury and meeting the enrollement criteria were eligible. INTERVENTIONS: Swab cultures of both internal nares were performed within 72 hrs of readmission and cultured for S. Aureus. Patients were prospectively monitored for S. Aureus infections until discharge. MEASUREMENTS AND MAIN RESULTS: Admission nasal cultures were positive (NC+) for S. aureus in 144 of the 776 patients cultured. Forty of the 144 NC+ patients had isolated head (37) or high cervical spine (3) injury, and 11 of that group (27.5%) developed S. aureus infections. The remaining 104 patients positive for S. aureus on admission had no head injury (74) or head combined with torso and extremity injuries (30). S. aureus infection was diagnosed in 11 of the 104 patients (10.6%). The difference in incidence of infections is significant (p <.01), as is the difference in incidence of pneumonia (20% vs. 3.8%, respectively [p <.01]). Organisms causing pneumonia were often the same organisms isolated from the nares on admission. CONCLUSIONS: Nasal colonization with S. aureus at the time of severe head injury increases the risk of S. aureus pneumonia during hospitalization. Prophylactic measures against S. aureus pneumonia may help reduce the length and cost of hospitalization.

Adult↗

PubMed1989

Cloning and sequence determination of six Staphylococcus aureus beta-lactamases and their expression in Escherichia coli and Staphylococcus aureus.

The plasmid-encoded beta-lactamase genes of six strains of Staphylococcus aureus were cloned and shown to be expressed in Escherichia coli. The cloned genes were re-introduced into S. aureus via a shuttle vector, and expressed beta-lactamase. However, clones containing only the small amount of DNA found necessary for expression of ampicillin resistance in E. coli did not express beta-lactamase in S. aureus. Much larger pieces of DNA from the original plasmid were necessary to obtain expression in S. aureus. Some of the six strains of S. aureus synthesized beta-lactamase constitutively and some released only a small proportion of the enzyme into the medium. Both these characteristics were maintained in the clones so it is concluded that they are features either of the gene itself or of the surrounding DNA. The cloned genes were sequenced and the putative amino acid sequences of the beta-lactamases were compared. There are several differences between the sequences and in particular one change in the N-terminal region, at a position believed to be especially important for export of proteins from the cell, is thought to have a key effect on whether or not the enzyme is found in the medium.

Amino Acid Sequence↗

PubMed2004

Bloodstream infections caused by Staphylococcus aureus in a university hospital in Turkey: clinical and molecular epidemiology of methicillin-resistant Staphylococcus aureus.

In total, 177 patients with bloodstream infections caused by Staphylococcus aureus (BSISA) were investigated prospectively between June 1999 and June 2001. Of these, 19.8% had community-acquired BSISA, while 80.2% had nosocomial BSISA. Surgical intervention, foreign body, mechanical ventilation, total parenteral nutrition, and previous antibiotic treatment were found to be important risk factors for the nosocomial BSISA group. Secondary BSISA formed a greater proportion (62.9%) of community-acquired infections than of nosocomial infections (26.8%; p 0.0001). Catheter-related nosocomial BSISA was observed in 72.1% of patients. The suppurative complication rate was significantly higher among community-acquired infections (22.9%) than among nosocomial infections (6.3%; p 0.008). Of the nosocomial BSISA, 65.5% were methicillin-resistant. Analysis of 80 methicillin-resistant S. aureus isolates by pulsed-field gel electrophoresis identified ten main clones (A-J), but 61 (76.3%) of the 80 isolates belonged to clone A.

Adult↗

PubMed1989

Induction of resistance with heat-killed unencapsulated strains of Staphylococcus epidermidis against challenge with encapsulated strains of Staphylococcus epidermidis.

Active immunization of mice with high doses of heat-killed unencapsulated strains of Staphylococcus epidermidis, which were grown in brain heart infusion media, protected mice against challenge with encapsulated strains of S. epidermidis. The unencapsulated strains were capable of absorbing the protective antibody in rabbit hyperimmune sera prepared with the encapsulated strains. Also, mice treated with rabbit hyperimmune sera prepared with the unencapsulated strains were protected against challenge with the encapsulated strains. The protective activities of these rabbit hyperimmune sera were assumed to be essentially identical to those of the protective antibody induced by the encapsulated strains.

Animals↗

PubMed2004

Comparative analysis of antibiotic and antimicrobial biocide susceptibility data in clinical isolates of methicillin-sensitive Staphylococcus aureus, methicillin-resistant Staphylococcus aureus and Pseudomonas aeruginosa between 1989 and 2000.

AIMS: To analyse population minimum inhibitory concentrations (MICs) data from clinical strains of Staphylococcus aureus and Pseudomonas aeruginosa for changes over a 10-year period and to look for correlations between the antimicrobials tested. METHODS AND RESULTS: Data from the MIC study of 256 clinical isolates of Staph. aureus [169 methicillin-sensitive Staph. aureus (MSSA), 87 methicillin-resistant Staph. aureus (MRSA)] and 111 clinical isolates of Ps. aeruginosa against eight antimicrobial biocides and several clinically relevant antibiotics was analysed using anova, Spearman-Rho correlation and principal component analysis. Comparisons suggest that alterations in the mean susceptibility of Staph. aureus to antimicrobial biocides have occurred between 1989 and 2000, but that these changes were mirrored in MSSA and MRSA suggests that methicillin resistance has little to do with these changes. Between 1989 and 2000 a sub-population of MRSA has acquired a higher resistance to biocides, but this has not altered the antibiotic susceptibility of that group. In both Staph. aureus and Ps. aeruginosa several correlations (both positive and negative) between antibiotics and antimicrobial biocides were found. CONCLUSIONS: From the analyses of these clinical isolates it is very difficult to support a hypothesis that increased biocide resistance is a cause of increased antibiotic resistance either in Staph. aureus or in Ps. aeruginosa. SIGNIFICANCE AND IMPACT OF THE STUDY: The observation of negative correlations between antibiotics and biocides may be a useful reason for the continued use of biocides promoting hygiene in the hospital environment.

Anti-Bacterial Agents↗

PubMed1979

Surface properties of Staphylococcus saprophyticus and Staphylococcus epidermidis as studied by adherence tests and two-polymer, aqueous phase systems.

S. saprophyticus is an established pathogen in man, devoided of characteristics associated with pathogenicity in Staphylococcus aureus. The ability of this species to attach to cells from regions, viz. the urinary tract, where it acts as an invador and to cells from areas where it is known as a commensal, was compared to its behaviour in this respect with another staphylococcal species, viz. S. epidermidis. S. saprophyticus showed a preferenital adherence to human exfoliated urogenital cells, when compared with its ability to attach to skin and buccal cells from man and also when compared with procine cells from these regions. The profound ability to adhere to human exfoliated urogenital epithelial cells by far exceeded that of S. epidermidis, while no such species difference was found when testing porcine cells (S. saprophyticus is unknown as a urogenital tract pathogen in pigs). When studied in a two-polymer, aqueous phase system, S. saprophyticus and S. epidermidis were found to have a negative surface charge at pH 7.2, but the former carried a considerably higher surface charge density. Both staphylococcal species exhibited a poor hydrophobic interaction liability. These physico-chemical surface characteristics are briefly discussed with regard to the differential bacteria-cell interactions of these species.

Adhesiveness↗

PubMed1995

Comparative in vitro activities of LY191145, a new glycopeptide, and vancomycin against Staphylococcus aureus and Staphylococcus-infected fibrin clots.

Bactericidal activities of LY191145, an investigational glycopeptide, and vancomycin against Staphylococcus aureus were evaluated. Only LY191145 at a concentration 16-fold greater than the MIC was able to achieve 99.9% killing against methicillin-susceptible S. aureus (ATCC 25923; 8.0 h). Both agents demonstrated 99.9% killing against methicillin-resistant clinical isolate S. aureus MRSA67 over 24 h at concentrations 4-, 8-, and 16-fold greater than the MIC, but bacteria were killed at a more rapid rate by LY191145 (1.63 versus 5.02 h; P < 0.001). Against strain ATCC 25923- and MRSA67-infected fibrin clots, total reductions by LY191145 and vancomycin over 72 h were not statistically significantly different at a concentration 16 times the MIC (1.12 +/- 0.31 and 1.23 +/- 0.13 and 1.40 +/- 0.17 and 1.36 +/- 0.37 CFU/g; respectively). Increasing the drug concentration to 50 times the MIC did not alter the values significantly, and there was no statistically significant difference between the two agents. Overall, LY191145 exhibited more rapid bactericidal activity than vancomycin against S. aureus, and a concentration 16-fold greater than the MIC appears to be optimal.

Anti-Bacterial Agents↗

PubMed2000

A new class of genetic element, staphylococcus cassette chromosome mec, encodes methicillin resistance in Staphylococcus aureus.

We have previously shown that the methicillin-resistance gene mecA of Staphylococcus aureus strain N315 is localized within a large (52-kb) DNA cassette (designated the staphylococcal cassette chromosome mec [SCCmec]) inserted in the chromosome. By sequence determination of the entire DNA, we identified two novel genes (designated cassette chromosome recombinase genes [ccrA and ccrB]) encoding polypeptides having a partial homology to recombinases of the invertase/resolvase family. The open reading frames were found to catalyze precise excision of the SCCmec from the methicillin-resistant S. aureus chromosome and site-specific as well as orientation-specific integration of the SCCmec into the S. aureus chromosome when introduced into the cells as a recombinant multicopy plasmid. We propose that SCCmec driven by a novel set of recombinases represents a new family of staphylococcal genomic elements.

Amino Acid Sequence↗

PubMed2001

Bactericidal activities of two daptomycin regimens against clinical strains of glycopeptide intermediate-resistant Staphylococcus aureus, vancomycin-resistant Enterococcus faecium, and methicillin-resistant Staphylococcus aureus isolates in an in vitro pharmacodynamic model with simulated endocardial vegetations.

Daptomycin is an investigational lipopeptide antibiotic active against gram-positive organisms. The mechanism of action is unique, resulting in interference with cell membrane transport. The bactericidal activity of daptomycin was evaluated against glycopeptide-intermediate susceptible Staphylococcus aureus (GISA), vancomycin-resistant Enterococcus faecium (VREF), and methicillin-resistant S. aureus (MRSA) in an in vitro infection model with simulated endocardial vegetations. Simulated regimens of daptomycin at 6 mg/kg/day (D6) and 10 mg/kg/day (D10) were utilized. MICs and MBCs for daptomycin were determined in the absence and in the presence of albumin with the following results (MIC/MBC): for GISA-992, 0.5/1.0 and 16/16; for VREF-590, 2.0/2.0 and 32/32; and for MRSA-494, 0.25/0.25 and 1.0/4.0 microg/ml, respectively. During the first 8 h daptomycin significantly reduced the inoculum for all organisms. Daptomycin at 6 mg/kg/day and 10 mg/kg/day had log(10) CFU/g reductions of 5 and 6, 3.4 and 5, and 6.4 and 6.5 by 8 h for GISA-992, VREF-590, and MRSA-494, respectively. Against both GISA-992 and VREF-590, the D10 regimen achieved the limit of detection at 72 h, with D6 regimens showing slight regrowth. A concentration-dependent killing effect was noted to occur, with daptomycin demonstrating a more rapid and greater kill from the D10 versus the D6 regimen. The results of this study suggest that daptomycin demonstrates significant (P < 0.05) activity against gram-positive organisms in a simulated sequestered infection site.

Anti-Bacterial Agents↗

PubMed2005

Efficacy of Telavancin in a rabbit model of aortic valve endocarditis due to methicillin-resistant Staphylococcus aureus or vancomycin-intermediate Staphylococcus aureus.

The activities of telavancin and vancomycin were compared in vitro and in the rabbit model of aortic valve endocarditis against a methicillin-resistant Staphylococcus aureus strain, COL, and a vancomycin-intermediate S. aureus (VISA) strain, HIP 5836. Telavancin was bactericidal in time-kill studies at a concentration of 5 microg/ml against both COL and HIP5836. Vancomycin was bacteriostatic at 5 microg/ml and bactericidal at 10 microg/ml against COL and was bacteriostatic at 10 microg/ml against VISA strain HIP 5836. Compared to untreated controls, a twice-daily regimen of 30 mg/kg of telavancin reduced mean aortic valve vegetation titers of the COL strain by 4.7 log(10) CFU/g after 4 days of therapy and sterilized 6/11 vegetations compared to 3.4 log(10) CFU/g with 3/10 vegetations sterilized for a regimen of twice-daily vancomycin, 30 mg/kg; these differences were not statistically significant. Telavancin was significantly more effective than vancomycin in the VISA model, producing a 5.5 log(10) CFU/g reduction versus no reduction in CFU with vancomycin. In experiments comparing 2-day regimens of telavancin at 30 mg/kg and 50 mg/kg twice daily, organisms were rapidly eliminated from vegetations, but the effect was not different between the two doses. These results suggest that telavancin may be an effective treatment for endocarditis and other serious staphylococcal infections accompanied by bacteremia, including infections caused by staphylococci not susceptible to vancomycin.

Aminoglycosides↗

PubMed1998

Two-component anti-Staphylococcus aureus lantibiotic activity produced by Staphylococcus aureus C55.

Staphylococcus aureus C55 was shown to produce bacteriocin activity comprising three distinct peptide components, termed staphylococcins C55alpha, C55beta, and C55gamma. The three peptides were purified to homogeneity by a simple four-step purification procedure that consisted of ammonium sulfate precipitation followed by XAD-2 and reversed-phase (C8 and C18) chromatography. The yield following C8 chromatography was about 86%, with a more-than-300-fold increase in specific activity. When combined in approximately equimolar amounts, staphylococcins C55alpha and C55beta acted synergistically to kill S. aureus or Micrococcus luteus but not S. epidermidis strains. The N-terminal amino acid sequences of all three peptides were obtained and staphylococcins C55alpha and C55beta were shown to be lanthionine-containing (lantibiotic) molecules with molecular weights of 3,339 and 2,993, respectively. The C55gamma peptide did not appear to be a lantibiotic, nor did it augment the inhibitory activities of staphylococcin C55alpha and/or C55beta. Plasmids of 2. 5 and 32.0 kb are present in strain C55, and following growth of this strain at elevated temperature (42 degreesC), a large proportion of the progeny failed to produce strong bacteriocin activity and also lost the 32.0-kb plasmid. Protoplast transformation of these bacteria with purified 32-kb plasmid DNA regenerates the ability to produce the strong bacteriocin activity.

Amino Acids↗

PubMed1983

Expression of a cloned Staphylococcus aureus alpha-hemolysin determinant in Bacillus subtilis and Staphylococcus aureus.

A DNA sequence encoding Staphylococcus aureus alpha-hemolysin, which had been previously cloned and mapped in Escherichia coli K-12, was introduced into Bacillus subtilis BD170 and several strains of S. aureus by using plasmid vectors, some of which could replicate in all three organisms. The determinant was cloned on a 3.3-kilobase pair DNA fragment into B. subtilis by using the vector plasmid pXZ105 to form the hybrid plasmid pXZ111. B. subtilis cells harboring pXZ111 produced large zones of alpha-hemolysis after 18 h of growth at 37 degrees C on rabbit blood agar plates, and alpha-hemolysin activity was detected in supernatants prepared from growing cultures of this strain. The alpha-hemolysin was apparently secreted across the B. subtilis cell envelope. Polypeptides of molecular weights 34,000 and 33,000 were precipitated with anti-alpha-hemolysin serum from lysates prepared from BD170 cells harboring pXZ111. A hybrid replicon which could replicate in both E. coli and S. aureus was constructed in E. coli by ligating a HindIII fragment encoding the replication functions and chloramphenicol resistance genes of S. aureus plasmid pCW59 to the pBR322 alpha-hemolysin hybrid plasmid pDU1150. The DNA of this plasmid, pDU1212, was prepared in E. coli and used to transform protoplasts prepared from a non-alpha-hemolytic, nonrestricting strain of S. aureus RN4220. Some of the transformants contained plasmids which had suffered extensive deletions. Some plasmids, however, were transformed intact into RN4220. Such plasmids were subsequently maintained in a stable manner. pDU1212 DNA was prepared from RN4220 and transformed into alpha-hemolytic S. aureus 8325-4 and two mutant derivatives defective in alpha-hemolysin synthesis. All three strains expressed alpha-hemolysin when harboring pDU1212.

Bacillus subtilis↗