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Biomedical subjects

T C Sorrell

Publications and source records attributed to T C Sorrell.

At least 73 records · Page 4Linked to original sources
PubMed1990

Endocarditis associated with prosthetic cardiac valves.

Clinical features, microbiology, therapy and outcome of 26 episodes of prosthetic valve endocarditis occurring at Westmead Hospital from 1979 to 1989 were examined retrospectively. Presentation with a new or changed cardiac murmur was associated with early onset infection (within 12 months of prosthetic valve insertion; P = 0.0033). Corynebacteria were the commonest cause of early onset endocarditis (4 of 11 episodes) and Streptococcus viridans of late onset endocarditis (4 of 15 episodes). Nine of 11 episodes responded to antimicrobial therapy and 12 of 15 to medical-surgical therapy. There was a trend towards increased mortality in patients with early onset endocarditis presenting with a new or changed cardiac murmur (4 of 9 v. 1 of 17, P = 0.068), suggesting early surgery should be considered in this group. Analysis of antibiograms and published reports indicated that vancomycin and an aminoglycoside should be recommended as empirical therapy for endocarditis occurring 12 to 18 months after prosthetic valve insertion.

Aminoglycosides↗
PubMed1990

Horizontal transmission of Campylobacter jejuni amongst broiler chicks: experimental studies.

Horizontal transmission of Campylobacter jejuni was investigated in campylobacter-free broiler chicks. One hundred and twenty chicks housed individually, were provided with water containing 10(2)-10(9) c.f.u./ml C. jejuni. Colonization was rapid [47 of 73 (64%) positive cloacal cultures within 3 days and 65 of 73 (89%) within 7 days], dependent on C. jejuni strain and inoculum size but independent of chick age. Groups of 5-24 chicks in isolators were exposed to C. jejuni-contaminated water or colonized seeder chicks. Transmission occurred in 2-7 days concurrent with a gradual increase of C. jejuni in litter, water and feed. Environmental samples were culture-negative within 3 days following removal of colonized chicks. Treatment of 1-day-old chicks with adult caecal microbiota did not affect colonization. Treated and control chicks were all C. jejuni-positive within 3 days of seeder challenge.

Animal Feed↗
PubMed1989

Eicosanoids produced during interactions between Pseudomonas aeruginosa and alveolar macrophages are species-dependent.

Eicosanoid production during phagocytosis of pyogenic bacteria by rabbit alveolar macrophages was studied as a model of early events in the pathogenesis of pneumonia. Adherent alveolar macrophages, prelabelled with [3H]-arachidonic acid (AA), were incubated with live, opsonized Staphylococcus aureus or Pseudomonas aeruginosa (bacteria:macrophage ratio of 50:1) at 37 degrees C for 90 min. Supernatant eicosanoids were extracted and separated by reverse phase high performance liquid chromatography (RP-HPLC). While the amounts of labelled PGE2, TXB2, and PGD2 produced in response to the two organisms were equal, the amount of PGF2 alpha elicited by S. aureus amounted to three times that released during macrophage challenge with P. aeruginosa. Overall, preferential release of cyclooxygenase products occurred during phagocytosis of S. aureus. In contrast, eicosanoids identified presumptively as oxygenated metabolites of AA predominated in cultures challenged with opsonized P. aeruginosa. Live, non-opsonized P. aeruginosa elicited the same profile of eicosanoids, but in reduced amounts. Inhibitor studies indicated that these AA derivatives were not synthesized via the macrophage lipoxygenase pathway. Their production was dependent on the viability of P. aeruginosa. Macrophages challenged with opsonized, heat-killed P. aeruginosa resulted in production of an eicosanoid profile similar to that elicited by S. aureus. Secondary metabolism by P. aeruginosa of eicosanoids released from the macrophage did not contribute to the unique profile produced during the interaction of this organism with labelled macrophages. Our data indicate that during binding to macrophages, the primary human pathogen, P. aeruginosa, specifically modulates the profile of eicosanoids produced. This effect on inflammatory mediators may be of biological significance in the pathogenesis of pneumonia.

Animals↗
PubMed1988

Experimental colonization of broiler chicks with Campylobacter jejuni.

Minimal colonization inocula for two broiler strains of Campylobacter jejuni were determined in broiler chicks aged 2-3 days and 2 weeks. Individually housed chicks were exposed to a single oral or cloacal challenge. Diarrhoeal symptoms were absent in all 380 chicks included in the study. Chick susceptibility to the two C. jejuni strains varied. Colonization was effected by less than 10(2)-10(4) colony forming units (c.f.u.) via cloacal challenge and 10(4)-10(6) c.f.u. via the oral route. Colonization inocula for 2- to 3-day and 2-week-old chicks were similar. Treatment of 1-day-old chicks with fresh adult caecal flora or an anaerobic broth culture of adult caecal flora did not inhibit colonization after challenge with low-dose C. jejuni. Susceptible chicks were colonized rapidly. C. jejuni was detected in 167 of 189 (88%) colonized chicks within 3 days of challenge and persisted during the 2-week monitoring period. Our data suggest that colonization of broiler chicks with C. jejuni is effected more easily by the cloacal than the oral route and is independent of age.

Animals↗
PubMed1987

Extrapulmonary tuberculosis--a continuing problem in Australia.

Extrapulmonary tuberculosis (TB) remains a major health problem in Australia, with 24.3% of all new tuberculosis notifications in 1984 of extrapulmonary origin. We have reviewed our recent experience to assess the epidemiology and clinical features that may allow the earlier recognition and treatment of patients at risk for this disease. From 1980-1985, 51 cases of extrapulmonary TB were identified at Westmead Hospital. Thirty-eight patients were born outside Australia, mainly in South-East Asia and Europe. The commonest sites of disease were the lymph nodes, genitourinary tract, pleura and bone. Tuberculous lymphadenitis occurred predominantly in South-East Asians, whilst genitourinary tract disease was confined to Caucasians. A history of previous exposure to tuberculosis was obtained in 45% of patients. Fever, sweats and weight loss were noted in less than half of the cases. Changes consistent with old pulmonary disease were found on routine chest X-ray in 34% of cases. Laboratory confirmation of TB was made in 88% of cases, with typical histopathology in 90% and isolation of Mycobacterium tuberculosis in 69% of specimens submitted for analysis. Drug resistance was confined to isolates from South-East Asian patients.

Asia, Southeastern↗
PubMed1986

Propionibacterium acnes infection in neurosurgical patients. Experience with high-dose penicillin therapy.

Propionibacterium acnes is an underestimated but significant cause of cerebrospinal fluid (CSF) infection after neurosurgical procedures and in the presence of prosthetic devices. The most effective therapy for such infections has not been defined. We report here our experience with the use of high-dose penicillin in the treatment of six patients with postoperative infection which was caused by P. acnes. All patients received 3-4 million units of penicillin by the intravenous route every four hours, in combination with surgical drainage and removal of prosthetic devices where appropriate. All but one of the patients recovered from their infection. The remaining patient responded to penicillin but died of a massive intraventricular haemorrhage after 12 days. Isolates of P. acnes had minimal inhibitory concentrations to penicillin that ranged from 0.03-0.12 mg/L. No adverse reactions to penicillin were recorded. We conclude that high-dose intravenous penicillin therapy, in combination with surgical drainage and removal of foreign bodies, constitutes appropriate therapy for CSF infections that are due to P. acnes.

Combined Modality Therapy↗
PubMed1986

Campylobacter jejuni in broilers: the role of vertical transmission.

The role of broiler eggs in the transmission of Campylobacter jejuni to broiler grow-out flocks was investigated. Six breeder flocks supplying broiler eggs to hatcheries were examined for cloacal carriage of C. jejuni. Of 240 birds tested, 178 (74%) were C. jejuni-positive. Eggs from these birds examined for C. jejuni penetration of the egg shell indicated that 185 of 187 were campylobacter-free. Eggs from breeder flocks of unknown C. jejuni status were also examined for C. jejuni shell penetration. C. jejuni was not isolated from 142 eggs examined. A further 193 hatchery eggs incubated and hatched in the laboratory were campylobacter-free. Six farms containing the progeny of C. jejuni-positive breeder flocks were monitored. Eight hundred and forty birds from 14 flocks in these grow-out farms were campylobacter-free during their 6-week grow-out period. Experimental egg-penetration studies indicated that C. jejuni transmission via the egg is not easily effected. Of 257 eggs surface-challenged with C. jejuni, 162 hatched; all were campylobacter-free. Of 167 eggs injected with C. jejuni, 12 hatched; 2 of these were colonized with C. jejuni. Our data do not support a role for vertical transmission of C. jejuni in commercial broiler production.

Animals↗
PubMed1986

Is semiquantitative culture of central vein catheter tips useful in the diagnosis of catheter-associated bacteremia?

Semiquantitative culturing of catheter tips has been used as an index of catheter-related bacteremia. As the sensitivity and predictive values of this test have not been determined, we studied 780 tips from central vein catheters inserted into 440 critically ill patients in an intensive care unit. The results were correlated with clinical data for 30 bacteremic episodes which occurred in these patients, 14 of which were catheter related. When five or more colonies per plate were taken as a positive result, the sensitivity of the method was 92%, and the specificity was 83%. Although the predictive value of a negative result was excellent (99.8%), the predictive value of a positive result was low (8.8%) in our patient population, which had a relatively low incidence of catheter-related bacteremia (2%). We conclude that a semiquantitative culture technique is useful in the diagnosis of bacteremia associated with central vein catheters.

Bacteria↗
PubMed1986

Biliary sepsis. Reviewing treatment options.

Bactobilia is a frequent accompaniment of obstruction in the biliary tract, organisms present being normal intestinal aerobes and anaerobes. Bacterial colonisation of the bile may occur asymptomatically, may predispose to infection postoperatively, or may be associated with an attack of acute cholecystitis, occurring secondary to obstruction. The choice of an antimicrobial regimen for biliary infection should take into account the expected antibiotic sensitivities of organisms colonising bile, whether biliary obstruction or bacteraemia is present, and the activity of the antibiotic in bile. Often, high biliary concentrations of an antibiotic cannot be achieved due to obstruction, and in many cases high blood and tissue concentrations are of greater importance. Surgical prophylaxis should be reserved for patients at high risk of bactobilia (e.g. the elderly), when obstruction is present, for immunosuppressed patients, and those with artificial heart valves. A single perioperative dose of a 'first' or 'second generation' cephalosporin, gentamicin, or co-trimoxazole is effective. Antibiotic therapy for acute cholecystitis should be instituted if there is evidence of systemic toxicity, when surgery is to be delayed, or in patients with identified risk factors for bactobilia. Ampicillin or a cephalosporin may be appropriate in less severe disease, while in seriously ill patients, an aminoglycoside or cephalosporin with metronidazole or clindamycin is appropriate. Oral regimens include amoxycillin, an oral cephalosporin, or co-trimoxazole, in combination with metronidazole. In acute cholangitis, systemic therapy similar to that recommended for acute cholecystitis is indicated. Patients with recurrent cholangitis may have relatively antibiotic-resistant bacteria and efforts should be made to obtain a bacteriological diagnosis. Long term suppressant therapy with oral agents such as amoxycillin, cephalexin, or co-trimoxazole may be tried.

Anti-Bacterial Agents↗
PubMed1985

Prevention of sepsis associated with the insertion of intravenous cannulae. The experience in a coronary care unit.

The effect of a strictly maintained treatment protocol on the incidence of bacteraemia associated with peripheral intravenous catheters was studied in a coronary care unit. This protocol was supervised and carried out by nursing staff members. Before the introduction of the protocol in October 1981, Staphylococcus aureus bacteraemia associated with peripheral intravenous catheters had developed in five patients and led to the deaths of four of these patients. During this time, 2364 patients were admitted to the unit. Since October 1981, there have been no further episodes of systemic sepsis associated with peripheral intravenous catheters in 2279 patients admitted to the unit (P = 0.03; Fisher's exact test).

Australia↗
PubMed1985

Divergent expression of cytotoxic and microbicidal functions of rabbit alveolar and peritoneal macrophages: effects of non-specific activation and a natural microbicidal peptide, MCP-1.

Alveolar macrophages from NZW rabbits were intrinsically toxic to 6 xenogeneic cell lines and to Candida albicans in vitro. Macrophage-mediated candidacidal activity, but not cytostasis (inhibition of [3H] thymidine incorporation by target cells) or cytotoxicity (reduction in target cell number), was enhanced by prior injection of rabbits with Freund's complete adjuvant (FCA). Compared with alveolar macrophages, peritoneal macrophages were less candidacidal (median C. albicans killed, 24% versus 16%, p less than 0.01). In contrast to alveolar macrophages, peritoneal macrophages were not consistently cytostatic or cytotoxic. Only candidacidal activity was enhanced in FCA-elicited peritoneal macrophages (median C. albicans killed 28% versus 16% for resident peritoneal macrophages, p less than 0.01). Microbicidal concentrations of a cationic peptide produced by rabbit alveolar macrophages (MCP-1, 25-100 micrograms/ml) did not inhibit growth of 4 murine cell lines in vitro. Macrophage-mediated cytostasis and cytotoxicity were not enhanced by culture with exogenous MCP-1. Macrophage-mediated cytostasis was also unchanged in cultures containing 10(-5) 2' deoxycytidine. We conclude that rabbit macrophage populations are restricted in their expression of cytostatic and cytotoxic functions, that microbicidal activation can occur independently of cytotoxic activation and that in this system mechanisms of macrophage-mediated cytotoxicity to xenogeneic target cells are independent of MCP-1 and thymidine.

Animals↗
PubMed1985

A prospective study of adverse reactions associated with vancomycin therapy.

A prospective evaluation of the efficacy and safety of vancomycin was conducted in 54 consecutive patients over a 16-month period. Vancomycin was curative in 95% of 43 patients with proven infection. Drugs were ceased in six patients because of adverse reactions; in three of these vancomycin was considered the likely cause. Reactions included thrombophlebitis (20 of 54 patients), rash (4 of 54), nephrotoxicity (4 of 50), proteinuria (1 of 50) and ototoxicity (1 of 11 patients tested by audiometry). Thrombophlebitis occurred only with infusion through peripheral cannulae; nephrotoxicity and ototoxicity were confined to patients receiving an aminoglycoside plus vancomycin. We conclude that vancomycin, administered appropriately, constitutes safe, effective therapy for infections caused by susceptible bacteria.

Adolescent↗
PubMed1984

Systemic sepsis and intravenous devices. A prospective survey.

Seventy-five episodes of bacteraemia or fungaemia related to indwelling temporary intravenous devices were assessed by the Infectious Diseases Unit of The Westmead Centre, to determine the quality of care of these devices. The estimated incidence of systemic sepsis was 1% for all central venous catheters inserted and 0.1% for all peripheral venous catheters inserted. Sepsis was a major cause of death in 14 of 17 patients who died. Despite the existence of protocols for the insertion, management and early removal of intravenous devices, factors increasing the risk of sepsis included delay in the removal of the intravenous device and the presence of thrombophlebitis. Staphylococcus aureus was the most common isolate (41%); antibiotic resistant Gram-negative rods were also common (38%). It is concluded that continued education of resident and nursing staff is essential to minimize the risk of intravenous catheter-related sepsis.

Catheters, Indwelling↗
PubMed1984

Production of metabolic products of arachidonic acid during cell-cell interactions.

We studied interactions of human platelets and neutrophils with particular reference to the arachidonic acid pathway. Suspensions of [3H]arachidonate-labeled platelets and unlabeled neutrophils were stimulated with ionophore A23187. We detected several radioactive arachidonate metabolites, which are not produced by platelets alone. These included [3H]-labeled leukotriene B4 (LTB4), dihydroxy-eicosatetraeonic acid (DiHETE), and 5-hydroxy-eicosatetraenoic acid (5-HETE). DiHETE was formed when the platelet product [3H]12-HETE was added to ionophore-stimulated neutrophils. In addition, DiHETE was the major metabolite when [3H]5-HETE, a neutrophil arachidonate product, was added to stimulated platelets. We therefore suggest that upon stimulation, platelet-derived arachidonate can serve as precursor for the neutrophil-derived eicosanoids LTB4 and 5-HETE, and the platelet-derived product 12-HETE can be metabolized to DiHETE by stimulated human neutrophils. More recently we have shown that 12-HETE from thrombin-stimulated platelets can also be metabolized to a new product, 12,20-DiHETE, by unstimulated human neutrophils. It would appear that the platelet and neutrophil lipoxygenase pathways take part in cell-cell interactions--an observation that suggests a role for the neutrophils that are present in hemostatic plugs, thrombi, and inflammatory processes.

Arachidonate Lipoxygenases↗
PubMed1984

Exogenous ocular candidiasis associated with intravenous heroin abuse.

Seven young men developed disseminated candidiasis within 10 days of a single episode of intravenous heroin abuse. Sequential development of eye and skin lesions was noted in all cases. The bone or costal cartilage was involved in five. Ocular manifestations of candidiasis included episcleritis, chorioretinitis, and endophthalmitis. A presumptive diagnosis of candida chorioretinitis was established rapidly by culture of Candida albicans from involved skin and costal cartilage. Systemic therapy with amphotericin B plus 5-fluorocytosine resulted in cure of the episcleritis, chorioretinitis, osteomyelitis, costochondritis, and skin infection. Pars plana vitrectomy with local instillation of amphotericin B was required to cure chorioretinitis associated with vitreal extension of infection.

Adult↗
PubMed1984

Is the antimicrobial removal device a cost-effective addition to conventional blood cultures?

Two hundred and thirty-four blood cultures from 140 patients receiving antibiotics were processed using the antimicrobial removal device (ARD) in parallel with conventional blood cultures. One hundred and seventy cultures were obtained from patients suspected to have bacteraemia and 64 from patients known to have a positive conventional blood culture within the preceding three days. A total of 38 (16.2%) ARD-processed cultures were positive, compared with 21 (8.9%) conventional cultures (p less than 0.0001, Fisher's exact test). No instances of positive conventional cultures and negative ARD-processed cultures were identified. Thirty-three of 38 ARD-processed cultures became positive within 24 h, compared with 14 parallel conventional cultures (p less than 0.0001 Fisher's exact test). Although the yield and rapidity of isolation of bacteria from blood were improved by ARD processing, in only one of 140 patients did this information alter treatment. As the use of an ARD is associated with a sixfold increase in the cost of blood cultures, we conclude that, in our hands, general use of the device in patients receiving antibiotics is not cost-effective. Considerable care should be taken in selecting patients for ARD-processing of blood cultures.

Anti-Bacterial Agents↗