Enzymatic degradation of urinary indoxyl sulfate by Providencia stuartii and Klebsiella pneumoniae causes the purple urine bag syndrome

Purple discoloration of the colon found during autopsy: Identification of betanin, its aglycone and metabolites by liquid chromatography-high-resolution mass spectrometry

During autopsy of a 38-year-old man the forensic pathologist noted an atypical purple discoloration of the colon membrane. Hypothesis was that the discoloration could have been caused by ingestion of red beetroot. In order to exclude other toxicological causes for this finding and to analytically verify this hypothesis, colon membrane, blood and urine were screened not only for the typical forensically relevant substances but also for the main chromophoric beetroot compounds employing liquid chromatography-high-resolution mass spectrometry (LC-HRMS). Betanin (m/z 551.1495) and its aglycone betanidin (m/z 389.0973) were found in the extracts of colon membrane and urine. Betanin was detected in whole blood, and urinary analysis additionally revealed two metabolites: betanidin glucuronide (m/z 565.1294) and betanidin sulfate (m/z 469.0541) - showing the same fragmentation pattern as betanidin after the characteristic neutral loss of m/z 176.0315 and m/z 79.9554 for glucuronic acid and sulfate, respectively. This is the first time that betacyanins could be analytically confirmed as cause for a purple discoloration of the colon. Urine analysis further revealed that besides betanin itself betanidin phase II metabolites could be detected in human urine.

Purple urine bag syndrome

Purple urine bag syndrome (PUBS) is rare disease entity, occurs predominantly in constipated women, chronically catheterized and associated with bacterial urinary infections that produce sulphatase/phosphatase. The etiology is due to indigo (blue) and indirubin (red) or to their mixture that becomes purple. We present a case report of this rare phenomenon occurring in an 86-year-old woman.

Metabolite structure analysis by high-resolution MS: supporting drug-development studies

Effective characterization of drug metabolites in complex biological matrices is facilitated by mass spectrometers with high resolving power, mass accuracy and sensitivity. This review begins with an overview of high-resolution MS terminology and the different types of instrumentation that are currently available. Metabolite structure analysis offers unique challenges and, therefore, the different types of approaches used to solve problems are highlighted through specific examples. Overall, this review describes the value that high-resolution MS brings to drug-metabolism studies.

Indigogenic substrates for detection and localization of enzymes

Indoxyl esters and glycosides are useful chromogenic substrates for detecting enzyme activities in histochemistry, biochemistry and bacteriology. The chemical reactions exploited in the laboratory are similar to those that generate indigoid dyes from indoxyl-beta-d-glucoside and isatans (in certain plants), indoxyl sulfate (in urine), and 6-bromo-2-S-methylindoxyl sulfate (in certain molluscs). Pairs of indoxyl molecules released from these precursors react rapidly with oxygen to yield insoluble blue indigo (or purple 6,6'-dibromoindigo) and smaller amounts of other indigoid dyes. Our understanding of indigogenic substrates was developed from studies of the hydrolysis of variously substituted indoxyl acetates for use in enzyme histochemistry. The smallest dye particles, with least diffusion from the sites of hydrolysis, are obtained from 5-bromo-, 5-bromo-6-chloro- and 5-bromo-4-chloroindoxyl acetates, especially the last of these three. Oxidation of the diffusible indoxyls to insoluble indigoid dyes must occur rapidly. This is achieved with atmospheric oxygen and an equimolar mixture of K(3)Fe(CN)(6) and K(4)Fe(CN)(6), which has a catalytic function. H(2)O(2) is a by-product of the oxidation of indoxyl by oxygen. In the absence of a catalyst, the indoxyl diffuses and is oxidized by H(2)O(2) (catalyzed by peroxidase-like proteins) in sites different from those of the esterase activity. The concentration of K(3)Fe(CN)(6)/K(4)Fe(CN)(6) in a histochemical medium should be as low as possible because this mixture inhibits some enzymes and also promotes parallel formation from the indoxyl of soluble yellow oxidation products. The identities and positions of halogen substituents in the indoxyl moiety of a substrate determine the color and the physical properties of the resulting indigoid dye. The principles of indigogenic histochemistry learned from the study of esterases are applicable to methods for localization of other enzymes, because all indoxyl substrates release the same type of chromogenic product. Substrates are commercially available for a wide range of carboxylic esterases, phosphatases, phosphodiesterases, aryl sulfatase and several glycosidases. Indigogenic methods for carboxylic esterases have low substrate specificity and are used in conjunction with specific inhibitors of different enzymes of the group. Indigogenic methods for acid and alkaline phosphatases, phosphodiesterases and aryl sulfatase generally have been unsatisfactory; other histochemical techniques are preferred for these enzymes. Indigogenic methods are widely used, however, for glycosidases. The technique for beta-galactosidase activity, using 5-bromo-4-chloroindoxyl-beta-galactoside (X-gal) is applied to microbial cultures, cell cultures and tissues that contain the reporter gene lac-z derived from E. coli. This bacterial enzyme has a higher pH optimum than the lysosomal beta-galactosidase of animal cells. In plants, the preferred reporter gene is gus, which encodes beta-glucuronidase activity and is also demonstrable by indigogenic histochemistry. Indoxyl substrates also are used to localize enzyme activities in non-indigogenic techniques. In indoxyl-azo methods, the released indoxyl couples with a diazonium salt to form an azo dye. In indoxyl-tetrazolium methods, the oxidizing agent is a tetrazolium salt, which is reduced by the indoxyl to an insoluble coloured formazan. Indoxyl-tetrazolium methods operate only at high pH; the method for alkaline phosphatase is used extensively to detect this enzyme as a label in immunohistochemistry and in Western blots. The insolubility of indigoid dyes in water limits the use of indigogenic substrates in biochemical assays for enzymes, but the intermediate indoxyl and leucoindigo compounds are strongly fluorescent, and this property is exploited in a variety of sensitive assays for hydrolases. The most commonly used substrates for this purpose are glycosides and carboxylic and phosphate esters of N-methylindoxyl. Indigogenic enzyme substrates are among many chromogenic reagents used to facilitate the identification of cultured bacteria. An indoxyl substrate must be transported into the organisms by a permease to detect intracellular enzymes, as in the blue/white test for recognizing E. coli colonies that do or do not express the lac-z gene. Secreted enzymes are detected by substrate-impregnated disks or strips applied to the surfaces of cultures. Such devices often include several reagents, including indigogenic substrates for esterases, glycosidases and DNAse.

Purple urine bag syndrome in nursing homes: ten elderly case reports and a literature review

Purple urine bag syndrome (PUBS) is a rare occurrence, in which the patient has a purple-colored urine bag following urinary catheterization for hours to days. Most of authors believe it is a mixture of indigo (blue) and indirubin (red) that becomes purple. Previous study showed that PUBS occurred predominantly in chronically catheterized, constipated women. We collected 10 elderly patients with PUBS in two nursing homes. The first two cases were identified by chart review in 1987 and 2003, and then later eight cases (42.1%) were collected among 19 urinary catheterized elderly in the period between January 2007 and June 2007. In the present report, PUBS probably can occur in any patients with the right elements, namely urinary tract infection (UTI) with bacteria possessing these enzymes, diet with enough tryptophan, and being catheterized. Associations with bed-bound state, Alzheimer’s, or dementia from other causes are reflections of the state of such patients who are at higher risk for UTI, and hence PUBS occurred. Although we presented PUBS as a harmless problem, prevention and control of the nosocomial catheter-associated UTIs (CAUTIs) has become very important in the new patient-centered medical era. Thus, we should decrease the duration of catheterization, improve catheter care, and deploy technological advances designed for prevention, especially in the elderly cared for in nursing homes.

Catheter associated urinary tract infection: what is it, what causes it and how can we prevent it?

Catheter associated urinary tract infection (CAUTI) is one of the most frequently encountered health care associated infections today. Indwelling urinary catheters frequently become colonised with micro-organisms but the majority of cases will be asymptomatic. Differentiation between such colonisation and CAUTI is important for patient management, but unfortunately is not straightforward. This article discusses the diagnosis, causative microbiology and pathogenesis of CAUTI, and briefly considers complications of catheterisation and how these might be prevented.

Purple urine bag syndrome: a community-based study and literature review

AIM

Purple urine bag syndrome (PUBS) is considered as an uncommon phenomenon. This cohort study aimed to figure out the causative factors and the potential risks of PUBS.

METHODS

We recruited 84 patients with long-term urinary catheterization from seven nursing institutions and home care centre, then compared the differences of demographic, clinical, urine test and bacteriological data between the patients with and without PUBS.

RESULTS

The 2-month period prevalence of PUBS in chronic catheterized patients was 16.7%. PUBS-affecting patients had significantly higher proportion of female gender (P = 0.034), self oral intake (P = 0.036) and eating self-prepared food (P = 0.007). Otherwise, no statistical associations were found. Five different bacterial species were isolated from the urine of PUBS-affecting patients. No sequelae were found after forward follow-up for 6 months. We further discuss the associations between certain factors and PUBS according to literature review and the results of our study.

CONCLUSION

PUBS is not as rare as we thought before. The causative factors of PUBS have not been clearly characterized. It may be the combination of several factors that cause the PUBS. Female gender and food content were found to be associated factors of PUBS in our study. Asymptomatic PUBS is unnecessary to be treated by antibiotics.

[Biochemical and bacteriological investigation of six cases of purple urine bag syndrome (PUBS) in a geriatric ward for dementia]

AIM

Purple urine bag syndrome is a condition in which the urinary catheter bag turns purple. A tryptophan-indigo hypothesis has been proposed as the mechanism of PUBS, in which bacterial decomposition of tryptophan in gut associated with chronic constipation, bacterial overgrowth in the urinary tract and alkaline urine causes production of indigo and discoloration. We considered that further investigation of cases was needed.

METHODS

We investigated 6 cases exhibiting PUBS (3 males and 3 females).

RESULTS

All cases had chronic constipation. Oral ingestion was impossible in one case. PUBS disappeared after antibiotic treatment (3 cases) or spontaneously (one case). Alkaline urine and indicanuria were not found in all cases that showed the disappearance of PUBS. In bacterial culture of urine during the exhibition of PUBS, Enterococcus faecalis was isolated together with Morganella morganii (3 cases) and Pseudomonas aeruginosa (one case). Single infections by Klebsiella pneumoniae or Citrobacter species were also found. After disappearance of PUBS, infected bacterial species changed but no cases showed sterile urine. Urine and blood alpha-amino-n-butyric acid levels reduced after the disappearance of PUBS whereas tryptophan levels did not show related changes. In one case, blood protein concentration increased after the spontaneous disappearance of PUBS. Indicanuria and alkalization of urine from urinary catheter bag were more intense than of fresh urine.

CONCLUSIONS

The present results generally support the 'Tryptophan-indigo hypothesis'. Furthermore, it was suggested that additional factors associated with the occurrence of PUBS are an environment that facilitates specific bacterial growth in a hospital as well as abnormal metabolism relating to alpha-amino-n-butyric acid and reduced protein synthesis in patients.

Purple urine bag syndrome with acidic urine

Purple discoloration of a urinary catheter bag is very rare. This phenomenon is known as the purple urine bag syndrome. It is associated with urinary tract infections occurring in catheterized patients, generally elderly females with significant co-morbidities and constipation. The urine is usually alkaline. We present a unique case of this rare and interesting phenomenon occurring in acidic urine and discuss the pathophysiology.

An association of purple urine bag syndrome with intussusception

We report a case of an elderly lady with a long-term suprapubic catheter who developed purple discoloration of urine around the same time as she developed intussusception. Purple urine bag syndrome is a benign condition known to be associated with intestinal stasis. However, this association with intussusception should be kept in mind before the patient is reassured.

[Purple urine bag syndrome: a case report]

The authors report a case of dark purple urine in a woman with bowel obstruction and bilateral percutaneous nephrostomy urinary diversion for 30 years. This colour was due to the presence of high urinary concentrations of 3-indoxyl sulphate due to the enzymatic activity of Providencia rettgeri. A favourable course was observed in response to antibiotics.

Mass spectrometry analysis of urine and catheter of a patient with purple urinary bag syndrome

INTRODUCTION

Purple urinary bag syndrome (PUBS) is considered to be a benign condition observed in the urinary catheter and bag in some catheterized patients with urinary tract infections. This syndrome is usually reported to occur in alkaline urine.

CASE REPORT

We report of a catheterized patient with PUBS and slightly acidic urine (pH 6-6.5). A novel analysis method was developed using high pressure liquid chromatography and mass spectrometry (HPLC/MS) to detect compounds that are thought to be associated with PUBS. Urine, urinary sediment, and the plastic collection system were assayed and quantitated using these methods. The potential toxicity of one of these compounds, indoxyl sulfate, is discussed.

CONCLUSIONS

The presence of PUBS in a catheterized patient with slightly acidic urine is reported. A novel method for the analysis of chemical components of PUBS and the first direct confirmation of the presence of indigo in the urine sediment and collecting system are described.

Quantitative analysis of enzymatic assays using indoxyl-based substrates

Hydrolysis of indoxyl-based substrates by hydrolytic enzymes is a commonly used semiquantitative detection system that generates a water-insoluble indigo dye which is difficult to quantify. This work describes the quantitative analysis and enzyme kinetics for alkaline phosphatase (AP) and 5-bromo-4-chloro-3-indoxyl phosphate (BCIP) in solution obtained by applying known solubilization methodology from the textiles industry to the enzymatic product. This proposal is based on the reduction of the tetrahalo-indigo blue dye in a basic medium with the aim of generating its aqueous-soluble parent compound termed indigo white, which gives a rich yellow color in solution and is fluorescent. A quantitative ELISA (where a soluble end product is required) is accomplished for first time using BCIP as substrate.

Indoxyl sulphate and the purple urine bag syndrome: a case report

A case of purple urine bag syndrome, a rare condition in which the urinary catheter bag of chronically catheterised patients develops a discolouration, is reported. The excretion of indoxyl sulphate, an intermediate in the causal mechanism of this unusual phenomenon, was measured using Ehrlich's reagent and found not to be elevated in this 77 year-old man, when compared to elderly male control subjects.

Purple urine bag syndrome in a hemodialysis patient

Purple urine bag syndrome (PUBS) is an uncommon disorder, in which the plastic disposable urinary catheter bag turns purple or blue following hours or days of urinary catheterization. The purple discoloration results from indirubin dissolved in the plastic mixing with indigo in the urine. Bacteria possessing indoxyl sulfatase degrade indoxyl sulfate into indirubin and indigo. Indoxyl sulfate is derived from the metabolism of tryptophan. PUBS usually occurs in chronic catheterized elderly women who are constipated and poorly ambulant. The clinical course is benign and rarely causes sepsis. This investigation reports a 61-year-old female diabetic patient with end-stage renal disease on maintenance hemodialysis, who had two episodes of blue or purple urine bag discoloration. The urine culture of the first episode yielded Klebsiella pneumoniae, whereas that of the second episode yielded Escherichia coli, Enterococcus faecalis, and Proteus vulgaris. Both episodes resolved following oral antibiotics treatment and placement of new foley catheters. To our knowledge, this is the first recorded case of PUBS in a dialysis patient.

Purple urine bag syndrome

The purple urine bag syndrome (PUBS) is a rare condition associated with chronic urinary catheterization. It is characterized by the purple discoloration of the urine, collecting bag, and tubing. A number of factors are involved, but not always present, in its development including female sex, urinary tract infection, constipation, indicanuria, and alkaline urine. Despite multiple theories that involve the complex tryptophan metabolism to the tubing dye, the cause remains elusive. The syndrome resolves usually after treatment of urinary tract infection or changing of the collecting bag. We present a case of a patient with purple urine bag syndrome and a pertinent literature review.

Independent actions on cyclin-dependent kinases and aryl hydrocarbon receptor mediate the antiproliferative effects of indirubins

Indirubin, a bis-indole obtained from various natural sources, is responsible for the reported antileukemia activity of a Chinese Medicinal recipe, Danggui Longhui Wan. However, its molecular mechanism of action is still not well understood. In addition to inhibition of cyclin-dependent kinases and glycogen synthase kinase-3, indirubins have been reported to activate the aryl hydrocarbon receptor (AhR), a cotranscriptional factor. Here, we confirm the interaction of AhR and indirubin using a series of indirubin derivatives and show that their binding modes to AhR and to protein kinases are unrelated. As reported for other AhR ligands, binding of indirubins to AhR leads to its nuclear translocation. Furthermore, the apparent survival of AhR-/- and +/+ cells, as measured by the MTT assay, is equally sensitive to the kinase-inhibiting indirubins. Thus, the cytotoxic effects of indirubins are AhR-independent and more likely to be linked to protein kinase inhibition. In contrast, a dramatic cytostatic effect, as measured by actual cell counts and associated with a sharp G1 phase arrest, is induced by 1-methyl-indirubins, a subfamily of AhR-active but kinase-inactive indirubins. As shown for TCDD (dioxin), this effect appears to be mediated through the AhR-dependent expression of p27(KIP1). Altogether these results suggest that AhR activation, rather than kinase inhibition, is responsible for the cytostatic effects of some indirubins. In contrast, kinase inhibition, rather than AhR activation, represents the main mechanism underlying the cytotoxic properties of this class of promising antitumor molecules.

Fluorescent assays to quantitate enzymatic activities yielding as end product an aqueous-insoluble indigo-blue dye

Hydrolytic enzymes acting upon indoxyl-derivatized substrates produce a water-insoluble indigo-blue dye. The generation of indigo dye works well in nonquantitative histochemical or diagnostic assays. For quantitative analyses however, the technique is unsuited. In this paper two fluorescent methods are described that permit quantitative measurement of sialidase/neuraminidase activity toward indoxyl-derivatized N-acetyl-neuraminic acid substrates. The first method is based upon the reaction of the sialic/ N-acetyl-neuraminic acid with pyridoxamine and Zn2+ to produce a fluorescent chelate. This method is not sialic acid-specific and could be used for the quantitation of alpha-oxo acids. The optimum conditions for sialic acid fluorescent chelation are described. The second method is based upon the fluorescence of the reaction intermediates, indoxyl- and indigo-white, by arresting their conversion to nonfluorescent indigo-blue. This method is suitable for measuring any enzymatic activity toward indoxyl-derivatized substrates. Enzyme kinetics derived for influenza viral neuraminidase using the two techniques are described in this paper.

A case-control study of purple urine bag syndrome in geriatric wards

The clinical background of purple urine bag syndrome (PUBS) has not yet been well characterized. In previous reports, clinical, biochemical, or bacteriological analyses were carried out using urine or bacteria from a limited number of patients. Other than one report, we are not aware of any case-control studies that compared the clinical, biochemical, or bacteriological background between patients with and without PUBS. To examine the risk of PUBS, we carried out a case-control study. Twenty-six patients, in three long-term care wards, who had been catheterized for more than 3 months with the same types of balloon catheters and who had the same type of disposable plastic urine bags were enrolled as the PUBS-positive case group (14 patients; 2 men and 12 women), and as the PUBS-negative control group (12 patients; 4 men and 8 women) were enrolled. The data for urine tests (pH, sugar, protein, leukocyte counts, and bacterial yields and species) were compared for the two groups. A relatively higher prevalence of PUBS was observed in female and alkaline-urine-producing patients. Bacteriological studies, using fresh urine collected through the catheter, showed that the bacterial counts were significantly higher, by 1 to 2 logs, in most samples from the case group than those from the control group (P = 0.012). Although a total of 66 bacterial strains, belonging to 12 separate species, were isolated from the urine accumulated in bags, no causative relationship between bacterial species and PUBS was observed. These data suggest that a higher bacterial yield in urine acts as the most important factor in PUBS, in combination with other facilitating factors, such as female-specific ones and the alkaline condition of urine.

Characterization of a major form of human isatin reductase and the reduced metabolite

Isatin, an endogenous indole, has been shown to inhibit monoamine oxidase, and exhibit various pharmacological actions. However, the metabolism of isatin in humans remains unknown. We have found high isatin reductase activity in the 105,000 g supernatants of human liver and kidney homogenates, and have purified and characterized a major form of the enzyme in the two tissues. The hepatic and renal enzymes showed the same properties, including an M(r) of 31 kDa, substrate specificity for carbonyl compounds and inhibitor sensitivity, which were also identical to those of recombinant human carbonyl reductase. The identity of the isatin reductase with carbonyl reductase was immunologically demonstrated with an antibody against the recombinant carbonyl reductase. About 90% of the soluble isatin reductase activity in the liver and kidney was immunoprecipitated by the antibody. The Km (10 microm) and k(cat)/K(m) (1.7 s(-1) x microm(-1)) values for isatin at pH 7.0 were comparable to those for phenanthrenequinone, the best xenobiotic substrate of carbonyl reductase. The reduced product of isatin was chemically identified with 3-hydroxy-2-oxoindole, which is also excreted in human urine. The inhibitory potency of the reduced product for monoamine oxidase A and B was significantly lower than that of isatin. The results indicate that the novel metabolic pathway of isatin in humans is mediated mainly by carbonyl reductase, which may play a critical role in controlling the biological activity of isatin.

Aspergillus antigen testing in bone marrow transplant recipients

AIMS

To assess the clinical usefulness of a commercial aspergillus antigen enzyme linked immunosorbent assay (ELISA) in the diagnosis of invasive aspergillosis (IA) in bone marrow transplant recipients, and to compare it with a commercial latex agglutination (LA) test.

METHODS

In total, 2026 serum samples from 104 bone marrow transplant recipients were tested. These comprised 67 sera from seven patients who had died with confirmed IA, 268 sera from nine patients who had died with suspected IA, and 1691 sera from 88 patients with no clinical, radiological, or microbiological signs of IA.

RESULTS

The ELISA was more sensitive than the LA test. All patients who were ELISA positive were also LA positive, and a positive LA result never preceded a positive ELISA. Twelve of 16 patients with confirmed or suspected IA were ELISA positive on two or more occasions, compared with 10 of 15 who were LA positive. ELISA was positive before LA in five patients (range, 2-14 days), and became positive on the same day in the remainder. Aspergillus antigen was detected by ELISA a median of 15 days before death (range, 4-233). Clinical and/or radiological evidence of IA was noted in all patients, and a positive ELISA was never the sole criterion for introduction of antifungal treatment. Two samples (one from each of two patients without IA) gave false positive results.

CONCLUSIONS

The aspergillus ELISA is a specific indicator of invasive aspergillosis if the criterion of two positive samples is required to confirm the diagnosis. However, the test is insufficiently sensitive to diagnose aspergillosis before other symptoms or signs are apparent, and hence is unlikely to lead to earlier initiation of antifungal treatment. It is therefore unsuitable for screening of asymptomatic patients at risk of invasive aspergillosis, but does have a useful role in confirming the diagnosis in symptomatic patients.

Comparison of three rapid methods, tributyrine, 4-methylumbelliferyl butyrate, and indoxyl acetate, for rapid identification of Moraxella catarrhalis

Moraxella catarrhalis can easily be differentiated from other oxidase-positive, gram-negative cocci with tributyrine, 4-methylumbelliferyl butyrate, or indoxyl acetate. All M. catarrhalis give positive reactions, and all Neisseria spp. give negative reactions. The 4-methylumbelliferyl butyrate tube test and indoxyl acetate strip test provide same-day identification of M. catarrhalis isolates.

Evaluation of the indoxyl acetate hydrolysis test for rapid differentiation of Campylobacter, Helicobacter, and Wolinella species

A total of 410 well-defined Campylobacter, Helicobacter, and Wolinella strains, comprising 26 named species, subspecies, and defined groups, were tested for indoxyl acetate hydrolysis by a disk method by using disks prepared at the Centers for Disease Control, Atlanta, Ga. All C. coli (43 strains), C. cryaerophila (34 strains), C. fennelliae (5 strains), C. fennelliae-Campylobacter-like organism 3 (2 strains), C. jejuni (66 strains), C. jejuni subsp. doylei (3 strains), hippurate-negative C. jejuni-C. coli (15 strains), "C. upsaliensis" (39 strains), H. mustelae (5 strains), W. curva (1 strain), and W. recta (1 strain) hydrolyzed indoxyl acetate. Four strains gave weak positive reactions, and the remaining 196 strains, which belonged to 15 species, subspecies, and defined groups, gave negative reactions. Of the 410 study strains, 246 and 125 strains were tested for indoxyl acetate hydrolysis by a disk method and a tube method, respectively, by using commercially produced disks. The disk method, regardless of source, required less time and interpretation than the tube method did. Better differentiation between Campylobacter spp. was obtained with the indoxyl acetate test than with the trimethylamine N-oxide test. The indoxyl acetate disk distinguished C. lari from C. jejuni and C. coli, C. cinaedi from C. fennelliae, and H. pylori from H. mustelae and suggested that W. succinogenes could be differentiated from W. recta and W. curva. The indoxyl acetate disk method could be performed in 5 to 30 min, was easy to read and interpret, and should be useful as a routine diagnostic test for identification of Campylobacter spp.

Identification of Branhamella catarrhalis in 2.5 min with an indoxyl butyrate strip test

Branhamella catarrhalis, an occasional cause of human respiratory infections, unlike most other members of the family Neisseriaceae, produces a butyrate esterase. This is capable of breaking the ester linkage between butyryl groups and carrier molecules. B. caviae and B. ovis, which are rarely encountered in pathological specimens, also produce butyrate esterase. This property can be used as a rapid test in the identification of B. catarrhalis. The recently reported rapid test for butyrate esterase relies on the release of methylumbelliferate, which can be detected only by using UV light after 5 min of incubation. In the rapid test described here, indoxyl is liberated from indoxyl butyrate by butyrate esterase and spontaneously forms indigo in the presence of oxygen. B. catarrhalis can be distinguished from other oxidase-positive, gram-negative cocci after 2.5 min by inoculating the organism onto a filter paper strip containing this compound.