Pathogenicity of stable L-phase variants of Staphylococcus aureus: failure to colonize experimental endocarditis in rabbits

Controlled evaluation of hypertonic sucrose medium at a 1:5 ratio of blood to broth for detection of bacteremia and fungemia in supplemented peptone broth

The value of hypertonic media in the detection of bacteremia and fungemia is controversial, since prior clinical trials have yielded conflicting results with different media. Earlier, we showed that the addition of 10% sucrose to supplemented peptone broth at a 1:10 ratio of blood to broth yielded better recovery of Staphylococcus epidermidis, the Enterobacteriaceae, Pseudomonas aeruginosa, and yeasts. To evaluate the effect of 10% sucrose on blood cultured at a 1:5 ratio, we compared the yield and speed of detection of clinically important microorganisms from adult patients in 5,839 blood samples cultured in supplemented peptone broth with 0.03% sodium polyanetholesulfonate with and without 10% sucrose. The atmosphere of incubation (open venting units), 1:5 ratio of blood to broth, and methods of processing were the same for both bottles. Recovery of facultative gram-positive (P less than 0.02) and gram-negative (P less than 0.02) bacteria was improved, but the recovery of anaerobic gram-negative bacteria was both reduced (P less than 0.01) and delayed (P less than 0.02) by sucrose. The total yield of microorganisms including fungi, however, was increased with sucrose. The effect of sucrose on blood cultures appears to depend on the ratio of blood to broth as well as on the medium used and strains of microorganisms encountered.

Controlled evaluation of hypertonic sucrose medium for detection of bacteremia and fungemia in supplemented peptone broth

Because the value of hypertonic media in detection of bacteremia and fungemia is controversial, we evaluated supplemented peptone broth (SPB) with 0.03% sodium polyanetholsulfonate with and without 10% sucrose in 5,439 paired blood cultures from adult patients. The aerobic atmosphere, 1:10 ratio of blood to broth, and methods for processing blood cultures were identical. Only cultures with adequate blood samples (greater than or equal to 4 ml) were compared statistically. More clinically important bacteria were recovered from SPB with sucrose (P less than or equal to 0.001), including Staphylococcus epidermidis, Enterobacteriaceae, and Bacteroidaceae. However, only one of nine isolates of Neisseria gonorrhoeae grew in SPB with sucrose. Staphylococci (P less than 0.001), Enterobacteriaceae (P less than 0.01), Pseudomonas aeruginosa (P less than 0.01), and yeasts (P less than 0.05) were detected 1 or more days earlier in SPB with sucrose. The effect of sucrose on blood cultures appears to be medium dependent, based on comparisons of our results with those of published reports.

Infective endocarditis associated with cell wall-deficient bacteria. Electron microscopic findings in four cases

Although cell wall-deficient bacteria have been isolated in vitro from cases of endocarditis, no pathogenic role has been established for these forms in human disease. One criterion difficult to satisfy is the demonstration of these variants in human tissue, and electron microscopic documentation has not been reported. Cardiac valvular vegetations from four cases of endocarditis were examined by electron microscopy because of unusual histologic features of minimal inflammation and organization and small organisms that stained poorly by Gram stain. Although cell wall-complete bacteria were identified in the specimens, each showed the presence of cell wall-deficient forms within the vegetations; these variants predominated in three cases. Since manifestations of infective endocarditis were present in three cases and conventional cultures were negative, the evidence indirectly suggests a pathogenic role for these aberrant bacteria in human disease.

Staphylococcus aureus bacteremia and endocarditis associated with a removable infected intravenous device

Records of 21 patients with Staphylococcus aureus bacteremia associated with a removable infected intravenous device were reviewed. Sixteen patients had a peripheral intravenous catheter, four had a central venous catheter and one had a transvenous cardiac pacer. The duration of the indwelling intravenous device in situ prior to the detection of infection ranged from two to 11 (mean 5.2) days. The infected intravenous device was promptly removed as soon as bacteremia was suspected. Endocarditis was diagnosed in eight patients: in two patients an aortic murmur developed; in two the diagnosis was made clinically and was confirmed at necropsy (one mitral and one aortic); in four the diagnosis was made at necropsy (two tricuspid and two atrial wall). In patients with Staph. aureus bacteremia associated with a removable infected intravenous device, the risk of endocarditis developing was significant.

In vivo behavior of revertants from Stahylococcus aureus L-phase variants compared with the parent strain

The in vivo behavior of revertants of Staphylococcus aureus L-phase variants were studied in mice. The Giorgio strain of S. aureus was induced into L-phase variants by methicillin. After 13 serial passages in methicillin agar and six passages in antibiotic-free agar, reversion occurred. Six revertants, all phage untypable, coagulase negative, and mannitol negative, were inoculated intravenously into Swiss albino mice in comparison with the parent strain. Inoculation of 10(8) colony-forming units resulted in 38% mortality at 28 days for the Giorgio group and 0 to 2% for the revertants. The geometric mean titer of staphylococci in the kidneys was 3.5 x 10(5) for the Giorgio group and 0.5 x 10(0) to 1.0 x 10(2) for the revertants. Serial colony counts of blood, lungs, spleen, liver, and kidneys in mice inoculated with 10(7) colony-forming units showed faster clearance and failure of the revertant to colonize the kidneys. It is concluded that the in vivo behavior of the L-phase revertants was vastly different from that of the parent Giorgio strain.

Pathogenicity of stable L-phase variants of Staphylococcus aureus: failure to colonize normal and oxamide-induced hydronephrotic renal medulla of rats

The direct intramedullary inoculation of stable L-phase variants of Staphylococcus aureus failed to colonize normal and hydronephrotic rat kidneys induced by oral feeding of oxamide.