streptococcus pneumoniae or pneumococcus bacterias

antibiotic bacteria bacterium biology cell cocci coccus dimensional disease gram graphic health human illness illustration immunization infection medical meningitis microbe microbial microbiology microorganisms microscope microscopic organism pandemic pathogen pathogenic pathology pneumococcal pneumococcus pneumonia pneumoniae positive prophylaxis purulent pyogenic respiratory science scientific sepsis sick sickness spherical staphylococci streptococcus surgical three virus