Ecological impacts of tributyltin on estuarine communities in the Hastings River, NSW Australia.

Oyster (Saccostrea commercialis) biomonitoring, assessment of oyster and gastropod (Bembicium auratum) abundance, and gastropod imposex were used to measure the significance of tributyltin (TBT) contamination in an intertidal mangrove forest. We studied the bioavailable levels of TBT in oysters approximately 1 km downstream and 2 km upstream from a TBT waste disposal site. We found observable declines in the abundance of oysters and gastropods correlated with the bioavailable TBT and these findings were confirmed by mapping oyster beds. Oyster cover near the disposal site ranged from 0% to 5% while downstream and upstream populations ranged in cover from 25-50% to 5-25%, respectively. Similarly, gastropod abundances at the disposal site were only 7% of the downstream population and 17% of the upstream population. Imposex was present in 90% of female B. auratum from populations near the disposal site but this effect declined more sharply than the population level effects.

Assessment of metals in fish from Lake Macquarie, New South Wales, Australia.

The concentrations of the metals cadmium, copper, mercury, lead, silver, selenium and zinc were measured in the muscle and gonad tissues of five species of fish, yellowfin bream (Acanthopagrus australis), silverbiddy (Gerres subfasciatus) and trumpeter whiting (Sillago maculata), southern log finned goby (Favonigobious lateralis), and the halfbridled goby (Arenigobius frenatus) from the contaminated Lake Macquarie NSW and three relatively uncontaminated reference estuaries, Wallis Lake, Port Stephens, and St. Georges Basin NSW. Fish from Lake Macquarie were found to have elevated concentrations of selenium, lead, cadmium, and zinc in one or both of these tissues in these species. Increased concentrations relative to background concentrations were most often observed at Cockle Bay, the site with the highest concentrations of these metals in sediments. The degree to which fish accumulated metals appeared to be related to life history characteristics of the species, with sediment-dwelling fish showing the greatest propensity to accumulate metals.

Assessment of metals in sediments from Lake Macquarie, New South Wales, Australia, using normalisation models and sediment quality guidelines.

Industrial activity since the 1890s and, more recently catchment development has resulted in significant metal contamination in Lake Macquarie, an estuary in New South Wales, Australia. This paper presents an analysis of metal concentrations in surface sediments from Lake Macquarie using normalisation models to estimate enrichment relative to natural background concentrations and by comparing concentrations with sediment quality guidelines (SQGs) and effects range median quotients to assess the potential for ecological harm. Of the 12 metals examined, cadmium, lead, mercury, selenium, silver and zinc were enriched in surface sediments throughout the lake. The greatest contamination was found in the north of the lake and, for selenium, also in areas adjacent to two power stations. Comparisons with SQGs and effects range median quotients found that sediments from a site in Cockle Bay had concentrations of metals with the highest likelihood of causing adverse effects on sediment associated biota, and that the likelihood adverse decreased with distance from Cockle Bay. Comparisons with historical sediment quality data indicated that there has been a marked reduction in surface metal concentrations throughout the lake over 15 years. Models could not be constructed for all metals due to low background concentrations. For most metals, simple linear regression models were adequate, but for selenium and arsenic a multiple regression model provided a better estimate of background concentrations. SQGs possibly overestimated effects for arsenic, which has naturally high concentrations in the lake and underestimated the potential for ecological effects in coarser sediments.

Using benthic recruitment to assess the significance of contaminated sediments: the influence of taxonomic resolution.

The use of small-scale experimental units as a means of evaluating the ecological effects of contaminated sediments was examined at the species, family, mixed and phylum levels of taxonomic resolution. Sediments were taken from various locations representing a range of contaminant loads. Containers with these sediments were placed in situ at a relatively uncontaminated location for 90 days. The containers were retrieved and the abundance of the macrofauna which recruited to the containers was estimated. The results showed that the composition of the benthic communities in the more highly contaminated sediments differed significantly from those in less contaminated sediments. Analyses at the different taxonomic levels showed that all but the phylum level data showed some differences in community structure among sediment types. The study showed that small-scale experiments are useful for examining the effects of contaminants and that higher levels of taxonomic resolution can be used to describe variations in the structure of benthic communities at this spatial scale.

Cefamandole versus cefazolin in vascular surgical wound infection prophylaxis: cost-effectiveness and risk factors.

PURPOSE: Recent studies of perioperative antimicrobial prophylaxis have indicated an improved efficacy of beta-lactamase-stable cephalosporins compared with cefazolin, the most commonly used prophylactic agent. Previous studies in our institution have revealed a superiority of cefamandole to cefazolin in patients undergoing heart surgery, although there was no difference between cefazolin and cefuroxime in patients undergoing peripheral vascular surgery. This study was therefore designed to compare cefamandole with cefazolin in wound infection prophylaxis in clean vascular surgery. METHODS: The study was conducted from August 1990 through May 1992 and consisted of 893 patients with aortic or infrainguinal arterial procedures randomized to receive either cefamandole or cefazolin. RESULTS: The difference in infection rates associated with cefamandole versus cefazolin prophylaxis (3.2% vs 1.9%, respectively) was not significant (p = 0.42). A cost savings of approximately $95,000 per year at our institution favors the continued use of cefazolin over cefamandole. Risk factor analysis was carried out for preoperative and postoperative events that might have predisposed to infection. Only preoperative use of aspirin and the postoperative finding of a lymphocele correlated with a higher infection rate. CONCLUSIONS: Cefazolin continues to be the most cost-effective antibiotic for prophylaxis in clean vascular surgical procedures.

Antibiotic therapy in septic shock.

Septic shock is a life-threatening illness characterized by hypotension, impaired organ function and/or failure, and metabolic abnormalities. Septic shock can develop in patients infected with a variety of gram-positive and gram-negative bacteria, viruses, fungi, rickettsiae, spirochetes, protozoa, and parasites. Immediate recognition, diagnosis, and treatment are key elements in reducing the morbidity and mortality associated with this condition. Rapid administration of appropriate antibiotics in correct doses plays a major role in patient survival. Infections with gram-negative bacteria appear to be associated with septic shock more than any other etiologic agent; therefore, antibiotic selection must include those drugs with superior gram-negative coverage. The selection of appropriate antibiotics should be based on sound clinical judgement plus knowledge of the antimicrobials used. The principles of rational therapy include the following: (1) know the type of microorganisms or suspected organism being treated; (2) be familiar with resistant organisms in both the community as well as the hospital; and (3) initiate combination therapy with a beta-lactam antibiotic plus an aminoglycoside or use monotherapy with either a carbapenem or selected third generation cephalosporin. After culture results are known, the antibiotic regimen should be narrowed to cover the specific infecting microorganism using the least expensive, least toxic antibiotic available. The beta-lactam antibiotics include all penicillins, cephalosporins, carbapenems, and monobactams. Penicillins with extensive gram-negative coverage include all the carboxy (carbenicillin, ticarcillin, and ticarcillin plus clavulanic acid) and ureido (piperacillin, mezlocillin, azlocillin) penicillins. The third generation cephalosporins (cefoperazone, cefotaxime, ceftazidime, ceftizoxime, ceftriaxone, and moxalactam) have the broadest gram-negative coverage within the cephalosporin family.(ABSTRACT TRUNCATED AT 250 WORDS)

Selecting cost-effective antimicrobial prophylaxis in surgery: are we getting what we pay for?

The acquisition, administration, and infection-related expenses associated with the use of cefazolin or cefamandole during a prospective randomized comparison of antimicrobial prophylaxis in cardiac surgery were compared. Although the acquisition cost and administration charges related to the use of cefamandole were in excess of those incurred with cefazolin, differences in the charges associated with treating the wound infections that failed prophylaxis with each regimen made cefamandole the more cost-effective prophylactic agent (mean total of $766 per cefazolin recipient vs. $315 per cefamandole recipient). Analysis of prophylactic antimicrobials should include the expenses associated with "prophylactic failures." The agent that is least expensive for the pharmacy may not be the most cost-effective choice for the institution.

Efficacy of cefazolin, cefamandole, and gentamicin as prophylactic agents in cardiac surgery. Results of a prospective, randomized, double-blind trial in 1030 patients.

In an effort to develop an improved regimen of antibiotic prophylaxis in cardiac surgery, 1030 patients who were to have elective cardiothoracic surgery involving a median sternotomy were selected at random to receive cefamandole or cefazolin, with or without gentamicin, in a prospective double-blind study. Cefazolin was significantly less effective than cefamandole at both the sternal (1.8% vs. 0.4%, respectively, p less than 0.05) and donor sites (1.3% vs. 0%, respectively, p less than 0.02). Seven Staphylococcus aureus infections occurred among cefazolin recipients as compared with no such infections among the patients receiving cefamandole (p less than 0.01). All five wound infections yielding fungi or gentamicin-resistant gram-negative rods occurred in patients who had received gentamicin as a second prophylactic agent. These data suggest that gentamicin has no role as a prophylactic antibiotic in cardiac surgery and that, compared with cefamandole, cefazolin offers unreliable prophylaxis against deep infection at both the sternal and donor sites.

Cefoxitin versus erythromycin, neomycin, and cefazolin in colorectal operations. Importance of the duration of the surgical procedure.

Perioperative parenteral cefoxitin was compared with oral erythromycin, neomycin and parenteral cefazolin in a prospective, double-blind, randomized evaluation of 119 patients undergoing colorectal operations. Patients receiving cefoxitin had a higher wound infection rate than patients receiving erythromycin-neomycin-cefazolin (12.5% v 3.2%, respectively, p = .06). A direct correlation existed between the duration of the operation and the infection rate. Cefoxitin prophylaxis was as effective as erythromycin-neomycin-cefazolin in patients undergoing surgical procedures of 4 hours or less (infection rates of 4.8% and 4.0%, respectively). However, for surgical procedures lasting more than 4 hours, 5 of 14 patients (37.5%) receiving cefoxitin developed a wound infection v 0 of 13 patients receiving erythromycin-neomycin-cefazolin (p less than .05). It is speculative as to whether frequent two-gram doses of cefoxitin given during the operation would provide prophylaxis equivalent to erythromycin-neomycin-cefazolin.

Antibiotic prophylaxis in vascular surgery.

Preoperative and intraoperative antibiotic prophylaxis of infection in peripheral vascular surgery has been widely used although controlled studies have been lacking. A randomized, a prospective, double-blind study of cefazolin versus placebo during 565 arterial reconstructive operations was performed at this hospital from February 1976 through August 1977. Among the 462 patients undergoing surgery of the abdominal aorta and lower extremity vasculature, there was a highly significant difference in the infection rates: 6.8% for placebo recipients versus 0.9% for cefazolin recipients (p less than .001). Of the 18 infections, four involved vascular grafts and all four graft infections occurred in the placebo group. Over 8% of abdominal wounds of patients receiving placebo became infected versus 1.2% of cefazolin patients (p less than .05). Groin wounds were infected infrequently, 1.1% for placebo patients versus none for cefazolin patients. No infections occurred among 103 brachiocephalic procedures. Skin antisepsis was analyzed retrospectively. Infection rates were significantly higher (p less than .01) following hexachlorophene-ethanol versus a povidone-iodine skin preparation. Adverse effects of cefazolin were carefully monitored: no rash, phlebitis, or emergence of resistant strains was observed. A breif perioperative course of cefazolin and povidone-iodine skin antisepsis are recommended in vascular reconstructive surgery of the abdominal aorta and lower extremity vasculature.