Adjunctive antimicrobials in surgery of soft tissue infections: evaluation of cephalosporins and carbapenems.

The authors report three trials of B-lactams and carbapenems for soft tissue infections treated on a surgical service: 1) cefmetazole versus cefoperazone, n = 44; 2) cefotetan versus cefoxitin, n = 24; and 3) meropenem versus imipenem, n = 44. A total of 138 hospitalized patients were enrolled with 112 meeting evaluability criteria. Four hundred twenty-three isolates were cultured (mean, three/patient) of which 67 per cent were aerobes and 33 per cent anaerobes. Cure rates for each trial were: 1) 93 per cent; 2) 92 per cent; 3) 100 per cent. Failures were caused by resistant organisms (Streptococcus group D, Bacteroides fragilis and Pseudomonas) appearing in incompletely drained infection sites. Three patients receiving meropenem had adverse effects (headache, nausea) and one receiving cefoxitin (truncal rash). Operative drainage and debridement remain the critical elements in therapy. Agents with longer half lives allowing twice daily dosing (cefmetazole and cefotetan) were as effective and less expensive than multiple doses of short-acting agents. The extended spectrum carbapenems are most useful for severe infections or resistant organisms.

Colectomy for necrotizing amebic pancolitis in early childhood with survival.

A case of necrotizing amebic pancolitis in a 6-year-old boy with asplenia, partial situs inversus, and cyanotic congenital heart disease is reported and the literature is reviewed briefly. Our patient was managed successfully by prompt colectomy, ileostomy, a Stamm gastrostomy, and extensive drainage of the peritoneal cavity with administration of metronidazole postoperatively and prolonged jugular vein Broviac catheter hyperalimentation. This child may be the first survivor of total colonic amebic necrosis in childhood. Necrotizing amebic colitis appears to be more hazardous in infancy and childhood than in adult years. Malnutrition and additional illnesses and malformations may produce greater immunocompromise in the very young, placing them at greater risk for the ultimate of amebic intestinal complications, total colonic necrosis and disintegration.

Substance P increases lymphocyte traffic and lymph flow through peripheral lymph nodes of sheep.

Substance P, an 11 amino acid residue vasoactive neurotransmitter peptide, has been found on acute infusion (50 micrograms) into cannulated afferent lymphatics of popliteal lymph nodes of sheep to produce marked elevations in both efferent lymph flow and in the outputs of both blast and small recirculating lymphocytes into popliteal node efferent lymph (chronically cannulated). These elevations were characterized by a delay in the onset of major elevations, a marked prolongation of the elevations and a substantially greater stimulative effect on the output of blast lymphocytes. It is suggested that the number and types of substance P receptors on lymphocytes and in sheep peripheral lymph nodes may be responsible for these observations. Infusion of substance P, known for involvement in pain impulse transmission, was able to briefly overcome anaesthesia-induced depression in lymphocyte traffic. The substance P-induced alterations in lymph flow and lymphocyte traffic in vivo were demonstrated to be due to local rather than systemic effects of substance P.

In vivo influences of phorbol ester and calcium ionophore on lymphocyte traffic, lymph flow and efferent lymph levels of thromboxane B2 in sheep.

In vitro systems have provided increasing evidence of significant lymphocyte transmembrane signalling by plasma membrane receptors which utilize antigen and other ligand activation of the inositol phosphate dual second messenger system of intracellular signalling. Elevation of intracellular Ca2+ and activation of protein kinase C are important products of these signals and appear to provide a complete set of mitogenic signals for both T and B cells. Calcium inophore and phorbol ester have been found to mimic these events in vitro and are here employed in vitro to study their effects on lymphocyte traffic and efferent lymph flow through primary peripheral lymph nodes of sheep and on the output into efferent lymph of the arachidonic acid metabolite, thromboxane B2. Calcium ionophore and phorbol ester were given alone or in combination to popliteal lymph nodes of sheep by drainage area injection or by acute infusion into cannulated afferent lympatics of study popliteal lymph nodes whose efferent lymphatic was chronically cannulated for study. The findings resembled those of drainage area immunization with an early increase in efferent lymph flow and prompt and marked depressions in the output into efferent lymph of both small recirculating and blast lymphocytes ('shutdown', 'recruitment'), followed by a marked increase in the output into efferent lymph of both small recirculating and blast lymphocytes. The greatest elevation in both small recirculating and blast lymphocyte outputs was at 24 and 48 h following phorbol ester and calcium ionophore administration. Acute phorbol ester and calcium ionophore administration was associated with a prompt and marked elevation in efferent lymph levels of thromboxane B2 which were of short duration. The findings observed here with lymph node drainage area infusion/injection of both phorbol ester and calcium ionophore are quite similar to those encountered in this sheep lymphocyte traffic model following popliteal lymph node drainage area immunization with killed Salmonella muenchen antigen.

Prompt elevations of PGE2 and thromboxane A2 metabolites in peripheral node efferent lymph of sheep following drainage area immunization.

In the past decade, the main interest in the involvement of prostaglandin E2 (PGE2) in the immune response has been concerned with its role in immunomodulation (suppression) both in vitro and in vivo. Comparatively little attention has been devoted to its immunostimulatory role. It has been suggested that PGE2, like histamine, may function as a 'double agent', initially triggering, facilitating and augmenting a stimulatory immune response and later modulating, limiting and contributing to the turning off of this response. We here report an early (within minutes) immunostimulatory involvement of PGE2 (and thromboxane A2) in the sheep, with prompt elevations in levels of PGE2 and thromboxane B2 in popliteal lymph node efferent lymph following drainage area immunization with killed Salmonella muenchen bacteria. These elevations were associated with an increase in efferent lymph flow and an equally prompt but limited depression of lymphocyte outputs into efferent lymph ('shutdown', 'recruitment'). Local increases in blood flow and vascular permeability probably play important roles in these events.

Substance P increases and prolongs increased output of T4 (CD4) lymphocytes from lymph nodes of sheep in vivo: is it a mediator of immunological memory?

There are receptors on lymphocytes for substance P which are found both on small recirculating and on blast lymphocytes. The principal effect of substance P on lymphocytes appears to be a stimulating one, both in vitro and in vivo. The in vivo administration of substance P to sheep by acute infusion into cannulated afferent lymphatics of peripheral lymph nodes has been found to stimulate efferent lymph flow and the output into efferent lymph of both small recirculating and blast lymphocytes. We here report that substance P both enhances and prolongs the enhancement of the output of T4 (CD4) lymphocytes from lymph nodes of sheep in vivo. This output-stimulating effect appears to be specific to T4 (CD4) lymphocytes and is associated with a depressant effect on the output of T8 (CD8) and B lymphocytes. The output-stimulating effect on small T4 (CD4) lymphocytes is quite prolonged, lasting in excess of 96 h after a single 50 micrograms acute infusion. A brief post-infusion depression in T4 (CD4) lymphocyte output is associated with an equally brief, but marked, elevation in the output into efferent lymph of the arachidonic acid metabolite, thromboxane B2. The output-stimulating effect of substance P on blast T lymphocytes is confined to the T4 (CD4) blast lymphocytes. Substance P or a similar molecule may be of value when a specific T4 (CD4) lymphocyte output stimulant effect is desired. A single prior (6 days) acute infusion of substance P into a popliteal lymph node via its cannulated afferent lymphatic produced profound changes in the response to nodal drainage area immunization with killed S. muenchen bacteria. The latent period prior to increased antibody production was abolished, as was the standard post-immunization 'shutdown' period of decreased output of lymphocytes into efferent lymph. These changes were accompanied by a marked and progressive increase in antibody production. The findings reported here suggest substance P-induced long-term potentiation (LTP) of the immune response and raise the question of an involvement of substance P as a major mediator of immunological memory.