In vitro activities of posaconazole, fluconazole, itraconazole, voriconazole, and amphotericin B against a large collection of clinically important molds and yeasts.

The in vitro activity of the novel triazole antifungal agent posaconazole (Noxafil; SCH 56592) was assessed in 45 laboratories against approximately 19,000 clinically important strains of yeasts and molds. The activity of posaconazole was compared with those of itraconazole, fluconazole, voriconazole, and amphotericin B against subsets of the isolates. Strains were tested utilizing Clinical and Laboratory Standards Institute broth microdilution methods using RPMI 1640 medium (except for amphotericin B, which was frequently tested in antibiotic medium 3). MICs were determined at the recommended endpoints and time intervals. Against all fungi in the database (22,850 MICs), the MIC(50) and MIC(90) values for posaconazole were 0.063 microg/ml and 1 mug/ml, respectively. MIC(90) values against all yeasts (18,351 MICs) and molds (4,499 MICs) were both 1 mug/ml. In comparative studies against subsets of the isolates, posaconazole was more active than, or within 1 dilution of, the comparator drugs itraconazole, fluconazole, voriconazole, and amphotericin B against approximately 7,000 isolates of Candida and Cryptococcus spp. Against all molds (1,702 MICs, including 1,423 MICs for Aspergillus isolates), posaconazole was more active than or equal to the comparator drugs in almost every category. Posaconazole was active against isolates of Candida and Aspergillus spp. that exhibit resistance to fluconazole, voriconazole, and amphotericin B and was much more active than the other triazoles against zygomycetes. Posaconazole exhibited potent antifungal activity against a wide variety of clinically important fungal pathogens and was frequently more active than other azoles and amphotericin B.

In vitro Gram-positive antimicrobial activity of evernimicin (SCH 27899), a novel oligosaccharide, compared with other antimicrobials: a multicentre international trial.

The antimicrobial activity of evernimicin (formerly SCH 27899), a novel oligosaccharide antimicrobial of the everninomicin class, was evaluated against four groups of Gram-positive pathogens: (i) Streptococcus pneumoniae (n = 1452); (ii) methicillin- or oxacillin-resistant Staphylococcus aureus (MRSA) and coagulase-negative staphylococci (MR-CoNS; n = 1427); (iii) enterococci (n = 1517); and (iv) non-pneumococcal streptococci (n = 1388), using the Etest method at each study centre throughout Eastern and Western Europe, Scandinavia, South Africa, Turkey and North America. Comparative MICs were determined for a variety of reference compounds, including vancomycin, quinupristin/dalfopristin, chloramphenicol, penicillin, ampicillin, oxacillin, ceftriaxone and ciprofloxacin. Evernimicin was highly active against all strains tested, with MIC90 values < or = 1.0 mg/L, ranging from 0.047 mg/L against S. pneumoniae to 1.0 mg/L against MRSA/MR-CoNS and enterococci. Compared with the reference agents, the MIC90 of evernimicin were lower against all species. Against MRSA and MR-CoNS the MIC90s of evernimicin, quinupristin/dalfopristin and vancomycin (the three most active agents) were 1.0, 1.5 and 3.0 mg/L, respectively. Against all species tested, the relative activities and spectra of these agents were: evernimicin > vancomycin > quinupristin/dalfopristin. The Etest proved to be reliable and reproducible, despite occasional interpretive difficulties caused by observer inexperience. Quality control results were excellent among the 33 participant sites. The results of this in vitro, multicentre, multinational study demonstrate that evernimicin possesses high antimicrobial activity against Gram-positive organisms that compares favourably with established antibacterial treatments and newer agents such as quinupristin/dalfopristin. Further clinical investigations of everninomicin class compounds appear warranted.

Aminoglycoside resistance mechanisms in clinical isolates of Pseudomonas aeruginosa from the Canary Islands.

Strains of Pseudomonas aeruginosa resistant to aminoglycoside antibiotics were selected from 152 clinical isolates. We identified two patterns of resistance correlating with the resistance mechanism characterized by changes in permeability, enzymatic modification due to the acetylating enzyme, AAC(6')-II, or a combination of both. We detected enzymatic activity of the phosphorylase enzyme, APH(3'), in all the isolates. We compared the mechanisms of resistance detected by three methods i.e., radioenzymatic assay, phenotype of resistance and DNA probes. The phenotype of resistance was tested using a kit developed by Schering-Plough Corp. Hybridization was made with 18 DNA probes for the most frequent genes encoding for aminoglycoside-modifying enzymes. All isolates with AAC(6') activity hybridized with the aac(6')-Ib probes and to a minor degree, with the aac(6')-IIb probe. None of the isolates showed hybridization with aph(3')-I, aph(3')-II, or aph(3')-III DNA probes. Serotyping of the strains showed that the O:11 serotype was the most frequent one in strains whose resistance was due to the AAC(6') enzyme. The O:6 serotype was associated with changes in permeability. Encoding of the resistance mechanism seemed to be chromosomal in all the strains.

In vitro activity of evernimicin and selected antibiotics against methicillin-resistant staphylococci: a 24-country study.

OBJECTIVE: To collect and analyze data on susceptibility of methicillin-resistant staphylococci to evernimicin and other antimicrobial agents. METHODS: Recent clinical isolates of methicillin-resistant staphylococci from 33 laboratories in North America, Europe and South Africa were investigated. RESULTS: Of the antimicrobial agents tested, evernimicin had the lowest MIC90s for methicillin-resistant Staphylococcus aureus and methicillin-resistant coagulase-negative staphylococci (0.75 and 1.0 mg/L, respectively). Resistance to ciprofloxacin and erythromycin was widespread, with higher levels of resistance in North America than in other regions. CONCLUSIONS: Susceptibility surveys help to determine the antimicrobial activity of new agents. Ciprofloxacin- and erythromycin-resistant staphylococci were prevalent throughout all regions.

The application of molecular techniques for the study of aminoglycoside resistance.

Aminoglycosides have been cinically used since 1944. Although this class of antibacterial agents has some nephrotoxicity and ototoxtcity issues, they continue to be part of the hospital armamentarium because of then rapid bactericidal activity, especially in combination with ß-lactams. Bacterial resistance to aminoglycosides can be caused by modifying enzymes, changes in cell permeability, and changes in the cellular target. The clinical observation of high levels of aminoglycoside resistance most often results from the acquisition of genes that encode modifying enzymes and are often plasmid-borne. Aminoglycosides are inactivated by three classes of enzymes:

Long-term performance and complications of the Tesio twin catheter system for hemodialysis access.

The Tesio twin catheter system (Medcomp, Harleysville, PA) was developed to overcome the problems with the existing central venous catheters in providing high-efficiency dialysis, such as inadequate blood flows, high recirculation rates, and need for surgical insertion. The relatively large internal lumens and multiple side holes in a spiral pattern allow for high blood flow rates and lower tendency to thrombosis. In this series, 82 catheter pairs were placed in 75 patients and monitored for a period encompassing 231 patient-months. We achieved mean nominal blood pump flow rates of 400 +/- 6 mL/min and an average recirculation of 4.6% +/- 0.5%. In 20 sets of catheters, a nominal blood flow rate of 388 +/- 6 mL/min was measured ultrasonically at 352 +/- 8 mL/min, representing an error of 36 +/- 5 mL/min. Thrombosis of the catheter occurred at a rate of one episode per 21 patient-months, and on all occasions responded to local instillation of urokinase. Despite having two exit sites, the infection rates were comparable to other catheters: exit site infections occurred at a rate of one per 21 patient-months and bacteremic episodes occurred at one per 11.5 patient-months, necessitating catheter removal once per 46 patient-months. Based on these data, we believe that the Tesio twin catheter system is an excellent long- and short-term vascular access for providing high-efficiency dialysis.

The most frequent aminoglycoside resistance mechanisms--changes with time and geographic area: a reflection of aminoglycoside usage patterns? Aminoglycoside Resistance Study Groups.

The aminoglycoside resistance mechanisms revealed by two surveys in Europe and other countries have been compared to those revealed in earlier studies. Mechanisms have become more complex in all bacterial groups. In Providencia, Serratia, Pseudomonas, Acinetobacter, and Staphylococcus species isolates, genus-specific mechanisms were very common, and it was not possible to see differences between different geographic areas. In other Enterobacteriaceae, the increasing complexity of mechanisms was most often caused by combinations of gentamicin-modifying enzymes with AAC(6')-I, which acetylates amikacin but not gentamicin. The occurrence of these combinations varied by geographical region and among hospitals. The frequency of these combinations correlated with aminoglycoside usage in either the geographical regions or in individual hospitals. These broad-spectrum combinations occurred most frequently in Citrobacter, Enterobacter, and Klebsiella species but also occurred in Escherichia, Morganella, Proteus, Salmonella, and Shigella species. Often the only clinically available aminoglycoside that retained its normal activity was isepamicin.

Comparison of ultrasound, CT, and MR imaging in the evaluation of candidates for TIPS.

To compare ultrasound (US), CT, and MRI in the evaluation of hepatic vascular anatomy, portal and splenic venous flow, and collateral pathways (varices and spontaneous shunts) in candidates for transjugular intrahepatic portosystemic shunting (TIPS), 17 patients with history of refractory variceal bleeding or intractable ascites underwent duplex US, contrast-enhanced CT, and MRI before TIPS. The appearance of portal and hepatic anatomy was graded from 1 (not visible) to 4 (excellent visualization) independently by four radiologists. Presence and direction of portal and splenic venous flow, and presence and location of varices and spontaneous portosystemic shunts were also assessed. Results and effects of interobserver variation were assessed for significance using Friedman's ANOVA and Wilcoxon's signed-rank test. MRI yielded higher scores than CT or US for hepatic veins (P < .0001) and inferior vena cava (P < .0001). MRI and CT scored better than US for portal vein branches (P = .012) and splenic vein (P = .0038). All tests demonstrated the main portal vein well, with no statistically significant difference. US and MRI were more sensitive than CT for detecting portal vein flow and direction (US 76%, CT 0%, MRI 82%). MRI was most sensitive for splenic vein flow and direction (US 41%, CT 0%, MRI 76%). CT and MRI were more sensitive than US in detecting varices (US 5%, CT 50%, MRI 58%) and spontaneous shunts (US 13%, CT 75%, MRI 75%). Interobserver variation did not influence results significantly P = .3691). MRI provides the most useful information and may be the preferred single imaging test prior to TIPS.

The changing nature of aminoglycoside resistance mechanisms and the role of isepamicin--a new broad-spectrum aminoglycoside. The Aminoglycoside Resistance Study Groups.

Aminoglycoside resistance mechanisms from recent studies were compared with those found in earlier studies in the USA and Europe for three pathogen groups. Among Citrobacter-Enterobacter-Klebsiella, four single mechanisms (AAc(3)-II, AAC(3)-I, ANT(2")-I and AAC(6')-I were found in all studies, but the most recent studies showed a significant increase in combinations of AAC(6')-I with the other common mechanisms. Since AAC(6')-I confers resistance to tobramycin, netilmicin and amikacin, combinations of it with the other gentamicin modifying enzymes conferred broad-spectrum resistance to all clinically available aminoglycosides except isepamicin. Similar changes occurred in Escherichia-Morganella-Proteus-Salmonella-Shigella except that the frequency of combinations was much lower and two additional single mechanisms - AAC(3)-IV and permeability - were also found frequently. Among aminoglycoside-resistant Pseudomonas, three mechanisms, AAC(6')-II, ANT(2")-I and permeability, were always common and remained common. However, combinations of the three mechanisms with each other and with other mechanisms were more common in the recent surveys. Different genes which produce different proteins with the same aminoglycoside-modifying activity are now known. The results of hybridisation studies with two aac(3)-I, 2 aac(6')-II and 4 aac(6')-I gene probes are presented. The most commonly occurring genes were: aac(3)-Ia, aac(3)-IIa, aac(6')-IIa, aac(6')-Ib and, in Serratia, aac(6')-Ic. The activity of isepamicin against amikacin resistant strain which produce AAC(6')-I can be related to differences in the structure of these two similar aminoglycosides at Position 3". Amikacin may form a stable complex with AAC(6')-I enzymes via binding interaction at Position 3 and 3". Isepamicin, which has a secondary amino group at Position 3", may only be able to interact at Position 3 and enzyme-isepamicin complexes are likely to be less stable.

Current status of carbon dioxide angiography.

The current status of carbon dioxide as an angiographic contrast agent is reviewed in this article. The physical characteristics of intravascular carbon dioxide, pertinent physiology, and principles of imaging are discussed. In addition, the advantages and limitations of carbon dioxide are compared with those of iodinated contrast. Examples of diagnostic and therapeutic procedures in both the arterial and venous systems show the utility of carbon dioxide angiography.

CO2 digital angiography: a safer contrast agent for renal vascular imaging?

Although the new nonionic contrast agents are safer than ionic agents, renal insufficiency and even death still occur occasionally. Therefore, we have explored the use of carbon dioxide (CO2) as an alternative angiographic contrast agent used in combination with digital subtraction angiography. Clinical observations have been made in over 800 patients. The images obtained are of equivalent diagnostic quality compared with those using conventional iodinated contrast agents. Recent advances in imaging, including "stacking," provide images comparable with iodinated contrast. Very small vessels, equivalent to third-order branches of the renal artery, can be imaged satisfactorily with CO2. Occasional studies with CO2 yield information not apparent with iodinated contrast agents, including excellent visualization of arteriovenous shunts, collateral circulations, malignant tumors, and minute amounts of arterial bleeding. Many of the advantages and disadvantages of CO2 derive from its special physical and chemical properties. The advantages include no allergic potentiation and no renal metabolism of CO2, because CO2 is cleared by the lungs and does not recirculate. Other advantages include delivery by very small catheters because of the low viscosity of CO2, minimal discomfort on injection, and very low cost. However, the low-density and compressibility of CO2 poses some special problems. Imaging requires digital subtraction angiography with electronic enhancement and injections require an experienced investigator and, ideally, a dedicated CO2 injector. The dedicated CO2 injector provides calculated, controlled dosing and rates for injection, while excluding the possibility of air contamination. The buoyancy of CO2 inhibits good filling of dependent vessels. Accordingly, CO2 does not normally produce good nephrographic images, although proximal renal arteries are normally shown clearly. Experimental studies in dogs, whose renal arteries have been injected repeatedly with very large doses of CO2, demonstrate only transient changes in renal blood flow and no endothelial cell damage. However, these studies also showed clearly that renal ischemia can occur due to a "vapor lock" phenomenon if the kidney is positioned vertically above the injection site, and recurrent injections are given without time for absorption of the arterially delivered CO2 boluses. Uncontrolled studies in over 800 patients have confirmed that CO2 likely has a very low renal toxicity. At the University of Florida, CO2 is the radiologic contrast agent of choice in patients with renal insufficiency, especially those with diabetes mellitus, and in those with pre-existing allergy to iodinated contrast agents. Further controlled clinical studies are required to define the true clinical utility and safety of CO2 compared with conventional radiologic contrast agents.

Permanent indwelling peritoneal access device for the management of malignant ascites.

The case presented demonstrates an alternative management approach for malignant ascites. A permanent indwelling peritoneal port for at-home, small-volume paracentesis, provided palliative therapy for a patient who had malignant ascites secondary to breast cancer. The device allowed paracentesis without the risk of repetitive peritoneal puncture or diuretic therapy.

Mediastinal mass and tracheal compression due to an aneurysm of a systemic-to-pulmonary collateral artery in a patient with pseudotruncus arteriosus.

A patient with pseudotruncus arteriosus who presented with a large mediastinal mass due to a systemic-to-pulmonary collateral artery aneurysm is reported. This aneurysm caused tracheal compression with resulting dyspnea and postobstructive pneumonitis, which are unusual presenting features in these patients. The differential diagnosis for a mediastinal mass arising in a patient with pseudotruncus arteriosus, or any other patient with possible systemic-to-pulmonary collateral arteries, should include aneurysm.

Characterization of the chromosomal aac(6')-Ic gene from Serratia marcescens.

The DNA sequence of the chromosomal aac(6')-Ic gene from Serratia marcescens, which had been previously cloned (H. M. Champion, P. M. Bennett, D. A. Lewis, and D. S. Reeves, J. Antimicrob. Chemother. 22:587-596, 1988) was determined. High-pressure liquid chromatographic analysis of extracts prepared from Escherichia coli carrying the chromosomal aac(6')-Ic gene on a plasmid confirmed the presence of 6'-N-acetyltransferase activity in this strain, which was suggested by the aminoglycoside resistance profile. DNA sequence analysis of the cloned 2,057-bp PstI fragment revealed several regions of homology to previously characterized sequences from GenBank, including the rpoD and tRNA-2 genes of E. coli. Subcloning experiments confirmed the coding sequence of the aac(6')-Ic gene to be at positions 1554 to 1992. The predicted amino acid sequence of the AAC(6')-Ic protein suggested that it was the third member of a family of AAC(6') proteins which included a coding region identified between the aadB and aadA genes of Tn4000 and an AAC(6') protein encoded by pUO490, which was isolated from Enterobacter cloacae. Primer extension analysis suggested that the -35 region of the aac(6')-Ic promoter overlapped a large palindromic sequence which may be involved in the regulation of the aac(6')-Ic gene. Hybridization experiments utilizing a restriction fragment from the aac(6')-Ic gene showed that all S. marcescens organisms carried this gene whether or not the AAC(6')-I resistance profile was expressed. Organisms other than Serratia spp. did not hybridize to this probe.

Correlation between aminoglycoside resistance profiles and DNA hybridization of clinical isolates.

DNA hybridization data and aminoglycoside resistance profiles (AGRPs) were determined for 4,088 clinical isolates from three studies (United States, Belgium, and Argentina). The correlation between susceptibility profiles and hybridization results was determined with nine DNA probes. For each of the seven aminoglycoside resistance profiles which we were able to test, the data suggested at least two distinct genes could encode enzymes which lead to identical resistance profiles. Furthermore, the DNA hybridization data showed that individual strains carried up to six unique aminoglycoside resistance genes. DNA hybridization revealed interesting differences in the frequencies of these genes by organism and by country.

Efficacy of automated biopsy guns versus conventional biopsy needles in the pygmy pig.

Debate over which biopsy needle is the best has intensified recently with the introduction of automated biopsy guns including the 18-gauge long-throw and short-throw Biopty, the 18-gauge Cook, and the 14- and 18-gauge Klear Kut. To evaluate the efficacy of these mechanized biopsy guns versus that of conventional manual biopsy needles in the acquisition of adequate tissue for histopathologic evaluation, open hepatic and renal biopsies were performed in 15 pygmy pigs. The specimens were evaluated separately in a double-blind fashion by two histopathologists using graded criteria. Overall, the best results were obtained with the manual 14-gauge Tru-Cut needle, the long-throw 18-gauge Biopty gun, and the 18-gauge Cook biopsy gun. By comparison, the aspiration-type needles did not perform as well when considered as a group. Several other needles scored well in the biopsy of either the liver or kidney, but not in both. Disappointing results were obtained with the Klear Kut guns (both 14- and 18-gauge) and the Vacu Cut and PercuCut needles.

Management considerations in treating metabolic abnormalities associated with theophylline overdose.

We treated a patient who intentionally overdosed with theophylline complicated by metabolic disturbances. Management of the patient's hypokalemia with moderate doses of potassium chloride resulted in hyperkalemia with associated electrocardiographic changes. The rapid clearance of theophylline due to the administration of oral activated charcoal was believed to be a contributing factor. It is likely that theophylline-induced hypokalemia is due to intracellular sequestration of potassium and that as the theophylline level decreases potassium will reequilibrate out of the cell. The case provides support for the conservative management of metabolite abnormalities associated with theophylline overdose.