Diagnosis and management of tuberculosis in transplant donors: a donor-derived infections consensus conference report

Mycobacterium tuberculosis is a ubiquitous organism that infects one-third of the world's population. In previous decades, access to organ transplantation was restricted to academic medical centers in more developed, low tuberculosis (TB) incidence countries. Globalization, changing immigration patterns, and the expansion of sophisticated medical procedures to medium and high TB incidence countries have made tuberculosis an increasingly important posttransplant infectious disease. Tuberculosis is now one of the most common bacterial causes of solid-organ transplant donor-derived infection reported in transplant recipients in the United States. Recognition of latent or undiagnosed active TB in the potential organ donor is critical to prevent emergence of disease in the recipient posttransplant. Donor-derived tuberculosis after transplantation is associated with significant morbidity and mortality, which can best be prevented through careful screening and targeted treatment. To address this growing challenge and provide recommendations, an expert international working group was assembled including specialists in transplant infectious diseases, transplant surgery, organ procurement and TB epidemiology, diagnostics and management. This working group reviewed the currently available data to formulate consensus recommendations for screening and management of TB in organ donors.

Review article: the effects of antitumour necrosis factor-α on bone metabolism in inflammatory bowel disease

BACKGROUND

Patients with inflammatory bowel disease (IBD) are at increased risk of osteoporosis. A number of studies have emerged in recent years indicating that tumour necrosis factor (TNF) blockade appears to have a beneficial effect on bone mineral density (BMD) in IBD patients.

AIMS

To provide a review of the available data regarding the effect of the currently licensed anti-TNF-α therapies on bone metabolism and BMD in IBD patients.

METHODS

A Medline search was performed using the search terms 'infliximab', 'bone metabolism', 'IBD', 'BMD', 'bone markers', 'adalimumab', 'bone disease', 'Crohn's disease' and 'ulcerative colitis'.

RESULTS

Infliximab has a beneficial effect on bone turnover markers in Crohn's disease (CD) patients in the short term. The longest study to date comprising 24 CD patients showed an overall improvement in two bone formation markers - b-alkaline phosphatase (P = 0.022) and osteocalcin (P = 0.008) at 4 months post-treatment. Moreover, the largest study to date comprising 71 CD patients showed significant improvement in sCTx, a bone resorption marker (P = 0.04) at week-8 post-treatment. There is little data looking at the effect of anti-TNF-α therapy on bone metabolism in ulcerative colitis. Moreover, the long-term effects of anti-TNF-α therapy on bone structure and fracture risk in IBD patients are currently not known. The effect of cessation of anti-TNF-α therapy on bone metabolism is also unknown.

CONCLUSION

Properly controlled long-term trials are needed to fully evaluate the impact of TNF blockade on bone mineral density.

Chromosome 5q candidate genes in coeliac disease: Genetic variation at IL4, IL5, IL9, IL13, IL17B and NR3C1

Genetic predisposition to coeliac disease (CD) is determined primarily by alleles at the HLA-DQB locus, and evidence exists implicating other major histocompatibility complex-linked genes (6p21) and the CTLA4 locus on chromosome 2q33. In addition, extensive family studies have provided strong, reproducible evidence for a susceptibility locus on chromosome 5q (CELIAC2). However, the gene responsible has not been identified. We have assayed genetic variation at the IL4, IL5, IL9, IL13, IL17B and NR3C1 (GR) loci, all of which are present on chromosome 5q and have potential or demonstrated involvement in autoimmune and/or inflammatory disease, in a sample of 409 CD cases and 355 controls. Thirteen single nucleotide polymorphisms were chosen on the basis of functional relevance, prior disease association and, where possible, prior knowledge of the haplotype variation present in European populations. There were no statistically significant allele or haplotype frequency differences between cases and controls. Therefore, these results provide no evidence that these loci are associated with CD in this sample population.

Haplotype variation at the IBD5/SLC22A4 locus (5q31) in coeliac disease in the Irish population

In addition to the well-established association of coeliac disease (CD) with HLA-DQ (6p21) and possibly CTLA4 (2q33), there is considerable evidence for a susceptibility locus on chromosome 5q, which contains many potential candidates for inflammatory disease, including a cluster of cytokine genes in 5q31. CD cases and controls were genotyped for four single-nucleotide polymorphism (SNP) markers that together characterize >90% of the haplotype variation at the IBD5 locus encoding, among others, the SLC22A4 gene. IBD5 and SLC22A4 map to 5q31 and have recently been associated with Crohn's disease and rheumatoid arthritis. Haplotype frequencies do not differ significantly between CD cases and controls in the Irish population, and therefore the chromosome 5 CD susceptibility locus most likely lies elsewhere on 5q.

A common p73 polymorphism is associated with a reduced incidence of oesophageal carcinoma

The incidence of oesophageal adenocarcinoma is rising; to date, no susceptibility genes have been identified. p73, a novel p53 homologue, maps to chromosome 1p36, a region commonly deleted in oesophageal cancers. p73 shares some p53-like activity, but in addition, may also play a role in gastrointestinal epithelial inflammatory responses. A non-coding p73 polymorphism (denoted AT or GC) may be functionally significant. We investigated whether this polymorphism might play a role in the aetiopathogenesis of oesophageal cancer. This was a case-control, retrospective study. 84 cases of oesophageal cancer (25 squamous and 59 adenocarcinoma) and 152 normal population controls were genotyped for this polymorphism. Informative cases were examined for p73 LOH within the tumour. AT/AT homozygotes were significantly less prevalent in the oesophageal cancer population (1/84 = 1.2%) compared to controls (15/152 = 9.9%) (P < 0.02), corresponding to an odds ratio of 0.11 (95% C.I. 0.02-0.6, P < 0.02), or 9-fold reduced risk. Moreover, AT/AT homozygotes were significantly less frequent in the cancer population than would be expected under the Hardy-Weinberg hypothesis (P = 0.0099). LOH at the p73 locus was observed in 37.8% (14/37) of the AT/GC heterozygotes studied; in all cases there was loss of the AT allele. Our findings indicate that p73 AT/AT homozygotes appear to be protected against the development of oesophageal cancer. Clinically, this observation could have implications in aiding identification of high-risk Barrett's oesophagus patients.

In vitro antimicrobial activities of novel anilinouracils which selectively inhibit DNA polymerase III of gram-positive bacteria

The 6-anilinouracils are novel dGTP analogs that selectively inhibit the replication-specific DNA polymerase III of gram-positive eubacteria. Two specific derivatives, IMAU (6-[3'-iodo-4'-methylanilino]uracil) and EMAU (6-[3'-ethyl-4'-methylanilino]uracil), were substituted with either a hydroxybutyl (HB) or a methoxybutyl (MB) group at their N3 positions to produce four agents: HB-EMAU, MB-EMAU, HB-IMAU, and MB-IMAU. These four new agents inhibited Staphylococcus aureus, coagulase-negative staphylococci, Enterococcus faecalis, and Enterococcus faecium. Time-kill assays and broth dilution testing confirmed bactericidal activity. These anilinouracil derivatives represent a novel class of antimicrobials with promising activities against gram-positive bacteria that are resistant to currently available agents, validating replication-specific DNA polymerase III as a new target for antimicrobial development.

Persistence of episomal HIV-1 infection intermediates in patients on highly active anti-retroviral therapy

Treatment of HIV-1-infected individuals with a combination of anti-retroviral agents results in sustained suppression of HIV-1 replication, as evidenced by a reduction in plasma viral RNA to levels below the limit of detection of available assays. However, even in patients whose plasma viral RNA levels have been suppressed to below detectable levels for up to 30 months, replication-competent virus can routinely be recovered from patient peripheral blood mononuclear cells and from semen. A reservoir of latently infected cells established early in infection may be involved in the maintenance of viral persistence despite highly active anti-retroviral therapy. However, whether virus replication persists in such patients is unknown. HIV-1 cDNA episomes are labile products of virus infection and indicative of recent infection events. Using episome-specific PCR, we demonstrate here ongoing virus replication in a large percentage of infected individuals on highly active anti-retroviral therapy, despite sustained undetectable levels of plasma viral RNA. The presence of a reservoir of 'covert' virus replication in patients on highly active anti-retroviral therapy has important implications for the clinical management of HIV-1-infected individuals and for the development of virus eradication strategies.

Chronic parvovirus B19 infection resulting in chronic fatigue syndrome: case history and review

The spectrum of disease caused by parvovirus B19 has been expanding in recent years because of improved and more sensitive methods of detection. There is evidence to suggest that chronic infection occurs in patients who are not detectably immunosuppressed. We report the case of a young woman with recurrent fever and a syndrome indistinguishable from chronic fatigue syndrome. After extensive investigation, we found persistent parvovirus B19 viremia, which was detectable by polymerase chain reaction (PCR) despite the presence of IgM and IgG antibodies to parvovirus B19. Testing of samples from this patient suggested that in some low viremic states parvovirus B19 DNA is detectable by nested PCR in plasma but not in serum. The patient's fever resolved with the administration of intravenous immunoglobulin.

Effect of zinc concentration in Mueller-Hinton agar on susceptibility of Pseudomonas aeruginosa to imipenem

The susceptibility of Pseudomonas aeruginosa to imipenem has been shown to vary according to zinc concentration in the media. MICs of imipenem for 68 unique clinical isolates of P. aeruginosa were determined in media supplemented with zinc at concentrations between 0.5 and 6.0 micrograms/ml. In agar containing up to 3 micrograms of zinc/ml, 75 to 82% of the strains were susceptible to imipenem at an MIC of < or = 4 micrograms/ml. In agar supplemented to contain 6 micrograms of zinc/ml, however, only 40% of the strains were susceptible to imipenem. Manufacturers should ensure that the concentration of zinc in commercial media is below 3 micrograms/ml to avoid false classification of isolates as resistant to imipenem.

Effect of time and temperature on inactivation of aminoglycosides by ampicillin at neonatal dosages

The administration of gentamicin at least 1 hour before administration of ampicillin in neonates has been advocated because of in vitro inactivation of aminoglycosides by beta-lactam antibiotics. This method would cause a delay in ampicillin dosing in the treatment of serious bacterial infections and unnecessarily complicate nursing procedures. We studied the effect of varying concentrations of ampicillin (50, 100, 200, and 400 micrograms/ml) on aminoglycosidic antibiotics in vitro with the use of stock solutions diluted in pooled sera obtained from cord blood and incubated samples at 25 degrees C, 37 degrees C, and 40 degrees C. We found inactivation of aminoglycosides to be dependent on time, temperature, and ampicillin concentration, but the degree of inactivation was small and does not support temporal separation of parenteral administration of ampicillin and aminoglycosides to neonates.

Imipenem stability in a predried susceptibility panel

We performed a 15-month study using 11 clinical strains and 1 control strain (ATCC 27853) of Pseudomonas aeruginosa to determine whether changes in the manufacturing process of Sensititre predried panels result in a reliable test of susceptibility to imipenem. MIC and breakpoint susceptibility results remained stable during the manufacturer's recommended shelf life of 18 months and compared well with standard agar disk diffusion and broth macrodilution results. Imipenem concentrations measured by high-pressure liquid chromatography were acceptable through 15 months but declined in the breakpoint panels by approximately 50% at 18 months. Between 9 months and panel expiration, 13 of 141 (9%) of the MIC panel packages had moisture entry, as indicated by pink desiccants, with a resultant loss of imipenem activity of 32 to 100%. It appears that the new manufacturing process produces MIC panels that are reliable for imipenem susceptibility testing until the labeled expiration date, provided that packages containing pink desiccants are not used.

Antibacterial organophosphorus compounds: phosphoranilidohydrazones of 5-nitro-2-furaldehyde

A series of phosphoranilidohydrazones of 5-nitro-2-furaldehyde was synthesized and evaluated for antibacterial activity. The series was prepared to examine the applicability of phosphoramidic hydrazones as carriers for the antibacterial nitrofuran moiety. Designed as analogues of nitrofurantoin, members of the series were chosen according to the Topliss approach to analogue design. The title compounds were devoid of gram-negative activity but possessed moderate antistaphylococcal activity. The most potent members of the series were equipotent with nitrofurantoin against Staphylococcus aureus. The relationship between structure and antistaphylococcal activity is discussed.

Rochalimaea elizabethae sp. nov. isolated from a patient with endocarditis

A Rochalimaea-like organism (strain F9251) was isolated from a patient with endocarditis after blood drawn for culture before antimicrobial therapy was subcultured onto blood and chocolate agars and incubated for 2 weeks in 5% CO2. The strain was phenotypically similar to known Rochalimaea species. The cellular fatty acid composition of strain F9251 was close to but distinct from those of the three known Rochalimaea species and was most similar to that of R. vinsonii. Labeled DNA from strain F9251 was 59 to 67% related to DNAs from type strains of the three described Rochalimaea species, and its 16S rRNA gene sequence was 98.9% or more homologous to their 16S rRNA gene sequences. These findings support classification of F9251 as a new Rochalimaea species, for which the name Rochalimaea elizabethae sp. nov. is proposed. The patient infected with the organism had large bacterial vegetations on his aortic valve and was cured with antibiotics and valve-replacement surgery. Recognition of the procedures required to identify this and other Rochalimaea species suggests that clinical laboratories should prolong the incubation times of cultures of blood and tissue from patients with suspected endocarditis, patients with fever of unknown origin, and immunocompromised patients with fever so that the full spectrum of disease caused by these organisms can be recognized.

Two cases of endocarditis due to Lactobacillus species: antimicrobial susceptibility, review, and discussion of therapy

Endocarditis caused by lactobacilli may lead to death or to relapse of infection, despite antimicrobial treatment. We report two cases of lactobacillus endocarditis in individuals with native bicuspid aortic valves who survived without relapse and review the 39 other cases reported in the literature. In only 15 previously reported cases have patients been cured with medical therapy alone. One of our patients, who was infected with Lactobacillus acidophilus, was cured by medical therapy alone, and our other patient, who was infected with Lactobacillus casei subspecies rhamnosus, required surgical replacement of his aortic valve. L. acidophilus was tolerant and L. casei subspecies rhamnosus was resistant to many antibiotics tested. Combinations of penicillin or daptomycin and gentamicin were synergistic by time-kill assay. Synergistic therapy with a penicillin and an aminoglycoside was effective clinically and appears to provide optimal medical treatment on the basis of microbiological data.

Disseminated, nonmeningeal gastrointestinal cryptococcal infection in an HIV-negative patient

Gastrointestinal cryptococcosis is extremely rare, especially in patients with no involvement of the central nervous system. We describe a 63-yr-old man undergoing prednisone therapy for chronic hepatitis and cirrhosis who presented with peritonitis, colitis, and skin lesions. Pathological studies revealed necrosis and numerous cryptococcal organisms in the colon, omentum, and skin, and cultures yielded Cryptococcus neoformans. The patient died of multisystem organ failure following emergency exploratory surgery performed when he had onset of symptoms of a bowel perforation after an endoscopic biopsy. Clinicians should be aware that gastrointestinal cryptococcosis can occur in the absence of infection of the central nervous system or lungs, and that it may affect relatively healthy patients who are immunocompromised because of splenectomy, chronic liver disease, or steroid therapy.

Randomized, double-blind trial of cefonicid and nafcillin in the treatment of skin and skin structure infections

We compared treatment with one daily intravenous dose of cefonicid and multidose nafcillin in 65 patients with severe infections of the skin or skin structure. Clinical cure or improvement was achieved in 91% of the patients given cefonicid and in 87% of the patients given nafcillin (P = 0.97). The use of cefonicid may allow outpatient therapy of some severe infections.

Mechanism of action and in vitro and in vivo activities of S-6123, a new oxazolidinone compound

The in vitro activity of S-6123, a synthetic antimicrobial compound of the new oxazolidinone series, was compared with those of other orally administered agents against 328 clinical isolates. The compound was moderately active (MICs, 16 to 64 micrograms/ml) against 90% of staphylococci, nonenterococcal streptococci, and Haemophilus influenzae, including strains resistant to beta-lactam antibiotics. S-6123 was minimally active against enterococci and facultative gram-negative bacilli. Nevertheless, the compound had significant activity in a lethal rat Escherichia coli peritonitis model at serum concentrations of one-tenth the MIC against the infecting organism. The drug demonstrated only bacteriostatic activity against susceptible organisms. Studies to define the mechanism of antibacterial action revealed that S-6123 inhibited ribosomal protein synthesis without inhibiting DNA or RNA synthesis. This compound represents a new series of antibacterial agents not related to any other antibacterial compound of natural or synthetic origin.

Activity and mechanism of action of DuP 105 and DuP 721, new oxazolidinone compounds

The in-vitro activities of DuP 721 and DuP 105, new oxazolidinone antibacterials, were compared with those of cefazolin, cephalexin, ciprofloxacin, clindamycin, oxacillin, penicillin, and vancomycin against Gram-positive cocci. DuP 721 was approximately four-fold more active than DuP 105 with an MIC of 2.0 mg/l for 90% of the Staphylococcus aureus, beta-haemolytic streptococcus and Streptococcus faecalis strains tested, and an MIC of 4.0 mg/l for 90% of the Str. faecium, penicillin-resistant Str. pneumoniae and viridans streptococcus strains tested. DuP 105 was most active against strains of Staph. epidermidis with an MIC of 4.0 mg/l for 90% of the strains tested. There was no cross resistance between these and the other antibacterial agents that were tested. Both oxazolidinones had bacteriostatic activity in broth against susceptible organisms. Both DuP 721 and DuP 105 inhibited ribosomal protein synthesis in a cell-free system. These synthetic, orally absorbable compounds represent a new series of antibacterial agents unrelated by chemical structure to any other currently available antimicrobial agents.

Phenazopyridine induced methaemoglobinaemia associated with decreased activity of erythrocyte cytochrome b5 reductase

A 25-year-old woman taking usual doses of phenazopyridine developed her third clinically significant episode of cyanosis. Life threatening methaemoglobinaemia was documented and was treated with methylene blue. The patient and several members of her family showed decreased activities of erythrocyte NADH-cytochrome b5 reductase, predisposing them to the development of clinically significant methaemoglobinaemia when challenged with oxidant drugs.

Mass transfer characteristics of hollow-fiber dialyzers and hemoperfusion devices

Clearance versus time tests were carried out on three charcoal-based hemoperfusion devices (Sandev, Becton-Dickinson and Gambro) using solutions of 1 gm/L sodium salicylate in a pH 7.4 buffer and in bovine blood at flow rates of 200 ml/min. Similar tests were performed on a Cordis Dow 2.5 m2 hollow-fiber dialyzer at a tube side flow rate (QB) of 200 ml/min. Buffer was pumped through the dialysate side at a flow rate (QD) of 400 ml/min. Two dialyzers were run in series at QB = 200 ml/min and QD = 500 or 1000 ml/min. Mass transfer resistances were computed from the test results. These values are useful in that they constitute an index of the intrinsic initial kinetics of solute transfer in each device. However, the clearance versus time curves indicate that these initial kinetics decrease at different rates for each hemoperfusion unit as sorption capacity begins to be depleted. In contrast, the initial clearances for the dialyzers remain at their initial values. These data reveal much about the relative mass transfer characteristics of these devices.

Omission of pepsin from simulated gastric fluid in evaluating activated charcoals as antidotes

Although simulated gastric fluid USP calls for 3.2 g of pepsin/liter, most researchers omit pepsin when evaluating adsorbents. The present results show that, although pepsin adsorbs strongly to activated charcoal, it does not interfere significantly with the adsorption of a typical drug like sodium salicylate. Therefore, its omission is justified. Gastric mucin also had almost no effect on salicylate adsorption.

Interference by tannic acid with the effectiveness of activated charcoal in "universal antidote"

Evidence is presented to show that tannic acid is responsible for the reduced effectiveness of "universal antidote" as compared with activated charcoal alone. Adsorption isotherm data indicate that tannic acid binds strongly to charcoal and hence uses up part of the adsorption capacity that would otherwise be available for binding of a drug or poison. Data on sodium salicylate adsorption from simulated gastric fluid, both with and without the presence of tannic acid, are presented that illustrate clearly that tannic acid interferes significantly with the adsorption of salicylate. Magnesium oxide, another component of "universal antidote," was found to offer no interference to salicylate adsorption, presumably because it does not adsorb to charcoal to any significant extent.