Interaction of alveolar macrophages with Staphylococcus aureus and induction of microbial L-forms during infection in rats.
In vivo cell interactions between Staphylococcus aureus and rat alveolar macrophages were investigated after intranasal inoculation during a 30-days period of examination. Some dynamic characteristics of microorganisms in the macrophages were examined by electron microscopy and acid phosphatase cytochemistry. It was found that at earlier infection intervals (days 3 and 7) the ingested cocci were sequestered in phagosomes and phagolysosomes and later many of the microbial cells were digested. An interesting finding was the intracellular appearance of cell wall-defective forms (L-forms) of S. aureus at later intervals (days 14 and 30 after challenge). Infection kinetics were evaluated by isolation and enumeration of colony-forming units of S. aureus from bronchoalveolar fluid and by assessment of blood and bronchoalveolar total and differential leukocyte counts. The results indicate that induction and survival of S. aureus L-forms may occur spontaneously in vivo. This phenomenon could explain some of the mechanisms, provoking the latent and relapsing lung infections.
Michailova
L
L
Department of Morphology of Microorganisms, Institute of Microbiology, Bulgarian Academy of Sciences, Sofia. michail@bas.bg
Stoitsova
S
S
Markova
N
N
Kussovski
V
V
Jordanova
M
M
Dimova
I
I
D000818:Animals; D001992:Bronchoalveolar Lavage Fluid / Q000382:microbiology; D015169:Colony Count, Microbial; D005260:Female; D016676:Macrophages, Alveolar / Q000382:microbiology* / Q000473:pathology / Q000648:ultrastructure; D008297:Male; D008854:Microscopy, Electron; D010587:Phagocytosis; D010588:Phagosomes / Q000382:microbiology / Q000473:pathology / Q000648:ultrastructure; D051381:Rats; D017208:Rats, Wistar; D013203:Staphylococcal Infections / Q000276:immunology / Q000382:microbiology* / Q000473:pathology; D013211:Staphylococcus aureus / Q000276:immunology / Q000472:pathogenicity / Q000502:physiology*