In contrast, most bacteria that are successful as parasites interfere to some extent with the activities of phagocytes or in some way avoid their attention. Bacterial pathogens have devised numerous and diverse strategies to avoid phagocytic engulfment and killing. Most are aimed at blocking one or more of the steps in phagocytosis, thereby halting the process. Phagocytes Bacteria can avoid the attention of phagocytes in a number of ways. Pathogens may invade or remain confined in regions inaccessible to phagocytes.
Some pathogens are able to avoid provoking an overwhelming inflammatory response.
Without inflammation the host is unable to focus the phagocytic defenses. Some bacteria or their products inhibit phagocyte chemotaxis. Fractions of Mycobacterium tuberculosis are known to inhibit leukocyte migration. Such a strategy hides the antigenic surface of the bacterial cell. Phagocytes cannot recognize bacteria upon contact and the possibility of opsonization by antibodies to enhance phagocytosis is minimized.