Pus

PUS (Latin pus, Greek ῥόον), an inflammatory exudate, i.e., a protein-rich fluid containing a large number of polymorphonuclear (neutrophil) leukocytes, also called here pus cells. However, pus cells are not a synonym for leukocytes: they are so-called degenerated or degenerating leukocytes, which constitute the main mass of the pus-forming elements. In most cases, pus also contains the causative agents of purulent inflammation, most often staphylococci, streptococci, meningococci, gonococci, less frequently other types (such as anaerobic bacilli, typhoid group bacilli, Pseudomonas pyocyaneus, very rarely Pseudomonas tuberculosis, Bacillus anthracis, syphilis spirochete, etc.). In the liquid part of pus (so-called pus serum), products of histolysis, proteolytic substances (enzymes), and tissue detritus are also found; sometimes a distinct admixture of mucus is clearly visible (in purulent catarrhs). Fibrin is usually absent, which is why pus never coagulates; fibrin found in pus may be a random admixture (e.g., during operations) or it may indicate the absence of proteolytic enzymes in the pus. Pus contains albumoses and peptones, which can independently of pyrogenic bacterial bodies cause fever. Histolytic processes in bacterial purulent infections are caused by the release by bacteria of proteolytic enzyme-like substances; on the other hand, autolytic (or heterolytic) enzymes may also form without the presence of bacteria due to the breakdown of tissue elements, in particular leukocytes. Pus cells contain glycogen, and in long-standing purulent processes also droplets of fat, which often gives both the pus itself and the walls of an abscess a distinct yellowish tint. The existence of proteids (the “hyaline” substance of Rovida) has also been proven in pus cells, which cause the property of pus to sometimes turn into a mucoid mass in a solution of common salt. This is why (for example, in the bladder during cystitis) pus can undergo a mucoid transformation. In addition to leukocytes, lymphocytes and epithelial cells (in purulent catarrhs) may be present in pus. Virchow’s former doctrine that pus is “transformed tissue,” i.e., that it is formed exclusively at the expense of autolysis of tissues and transformation (into leukocytes) of elements of these tissues (and regardless of whether they are epithelial or connective tissue), is now shared by very few, but in one form or another it still has supporters. Thus, the possibility of local formation of leukocytes (and therefore outside emigration; see Inflammation) is not denied; the possibility of polymorphonuclear “transformation” of tissue cells, for example of desquamated epithelium, is pointed out, and precisely in connection with those sharp changes in the tissue environment which are observed during inflammation. Thus, the question of the origin of the pus-forming elements cannot be considered solved in all details. The consistency of pus varies from liquid to more or less thick, sometimes creamy or distinctly mucoid. In the beginning of purulent inflammation, pus is usually liquid, less turbid (seropurulent infiltration); later it becomes more turbid and thick. Thick pus is a common phenomenon at the end of purulent inflammation, which is why the ancient physicians’ expression “pus bonum et laudabile,” indicating successful discharge from the body of the so-called materia peccans and emphasizing the favorable prognosis of the process, arose; thickening of pus indicates a decline in exudative phenomena and the beginning of reparative (e.g., granulation) processes. The color of pus is yellowish-green; in putrid inflammation it is gray, dirty green; in cocci infections a clear greenish hue predominates; blue-green pus is observed with infection by Pseudomonas aeruginosa; bloody shades are most often observed in streptococcal and ichorous lesions. In a quiescent state (in body cavities, in vitro), pus separates into 2 layers: the lower layer is turbid, thick, rich in formed elements, and the upper layer is more transparent. Sometimes this sediment is so significant that the upper layers of the fluid do not differ from serous exudate or even transudate, with which they can be confused, for example during punctures. The smell of fresh pus is specific, slightly sweet in appropriate cases, putrid; however, in acute purulent inflammation a special smell is often not felt. Pus has an alkaline reaction; during the formation of fatty and other acids in it, the reaction may become neutral or acidic. Specific gravity varies from 1.020 to 1.040. Pus serum consists of 913.7 parts water, 78.57 parts organic, and 7.73 parts inorganic compounds, thus standing close to blood serum. Pus in the body cavity, in abscesses (see), not finding an outlet for a long time, undergoes significant changes: pus cells and other formed elements completely decompose into fine-grained detritus (partly protein, partly fat), while the liquid parts are only slightly absorbed, which is explained by the presence of a pyogenic membrane around pus accumulations, and partly by the compression of draining lymphatic pathways. Decomposing proteins of pus may give rise to cholesterol crystals. Bacteria in old pus also undergo dissolution, which is probably explained by the isolation of pus accumulations and the weak possibility of renewal of nutrient substrates; sometimes in old abscesses changes in the cultural and biological properties of bacteria are observed, for example a decrease in their virulence. It should be borne in mind that the absence of bacteria in pus may be from the very beginning of purulent inflammation—this is the so-called aseptic purulent inflammation (such purulent inflammation can be caused by turpentine, croton oil, digoxin, calomel, kerosene, and other substances). Diagnosis of pus is easy, but still requires a certain caution: not all fluids (for example, in the crypts of the tonsils, in the Fallopian tubes, leukorrhea in the vagina) having a purulent character are actually pus; for example, necrotic softened areas (for example, in the liver during amebic dysentery), accumulations of mucus mixed with epithelium, abundant desquamation of the latter, and even food particles (“pus” plugs in the crypts of the tonsils) can simulate pus. To avoid errors, it is recommended to examine the fluid under a microscope. Accumulations of pus in body cavities are usually called empyema (empyema), for example empyema of the accessory nasal sinuses, pleural cavity, and appendix. If empyema has spread beyond its cavity and threatens to rupture through the skin, it is called empyema necessitate. The purulent process itself is also called “suppuratio” (Latin); the term “purulent” has the Latin synonym “purulentus”. See also Abscess, Blennorrhea, Inflammation. I. Davydovsky. GNUDI REFLEX (Gnudi), consisting of reflex extension of the foot with simultaneous adduction and supination, is caused by tapping on the lower part of the tendon of the m. tibialis posterior at the medial epicondyle (supine position, support of the foot with the hand, slight rotation of the ankle joint). It is observed in organic lesions of the pyramidal tract.