Rapid biochemical tests for characterization of the Mycoplasmatales

Survey of respiratory disease associated with Mycoplasma gallisepticum in British gamebirds (2016-2019): In vitro antibiotic sensitivity, pathology and detection of other pathogens

BACKGROUND

The causes of respiratory disease in British gamebirds were investigated during 2016-2019 following concerns about poorer responses to antibiotic treatment. Emphasis was placed on Mycoplasma gallisepticum, but other possible bacterial and viral causes were included, along with gross and histopathological examination.

METHODS

Clinical respiratory disease outbreaks were investigated.

RESULTS

Mycoplasma gallisepticum was detected by PCR in 65 of 69 outbreaks in pheasants and partridges and isolated from 56 of these. Partial mgc2 gene sequences from 28 M. gallisepticum isolates were compared, and 26 proved identical, suggesting the prevalence of a dominant sequence type. Minimum inhibitory concentration values for tiamulin, tylosin, tylvalosin, doxycycline and tetracycline were significantly higher than the reference strain but could not be correlated with treatment failures. Other bacterial species were isolated from sinuses but were not consistently correlated with disease. RT-PCRs detected coronaviruses in 18% of 49 outbreaks and avian metapneumovirus in 8%. Histopathological lesions were typical of M. gallisepticum sinusitis and significantly associated with M. gallisepticum PCR outbreak positivity.

CONCLUSION

Mycoplasma gallisepticum remains an important cause of respiratory disease in gamebirds. Synergism with other pathogens may have played a role in some outbreaks. Specific reasons for variable responses to antibacterial treatment were not identified.

Influences of swab types and storage temperatures on isolation and molecular detection of Mycoplasma gallisepticum and Mycoplasma synoviae

Routine diagnosis of Mycoplasma gallisepticum (MG) and Mycoplasma synoviae (MS) is performed by collecting oropharyngeal swabs, followed by isolation and/or detection by molecular methods. The storage temperature, storage duration and the type of swab could be critical factors for successful isolation or molecular detection. The aim of this study was to compare the influence of different types of cotton-tipped swab stored at different temperatures, on the detection of MG and MS. To achieve this, combined use of traditional culture analysis (both agar and broth), with modern molecular detection methods was utilized. Performances of wooden and plastic shaft swabs, both without transport medium, were compared. Successful culture of M. gallisepticum was significantly more efficient from plastic swabs when compared to wooden, whereas no difference was seen for the re-isolation of M. synoviae. Storage at 4°C compared to room temperature also increased the efficiency of culture detection for both Mycoplasma species. When stored at room temperature, PCR detection limits of both MG and MS were significantly lower for wooden compared to plastic swabs. The qPCR data showed similar detection limits for both swab types when stored at both temperatures. The results suggest that swabs with a plastic shaft are preferred for MG and MS detection by both culture and PCR. While a lower storage temperature (4°C) is optimal for culture recovery, it seems that both temperatures investigated here are adequate for molecular detection and it is the swab type which carries a greater influence.

Mycoplasma tullyi sp. nov., isolated from penguins of the genus Spheniscus

A mycoplasma isolated from the liver of a dead Humboldt penguin (Spheniscus humboldti) and designated strain 56A97^T, was investigated to determine its taxonomic status. Complete 16S rRNA gene sequence analysis indicated that the organism was most closely related to Mycoplasma gallisepticum and Mycoplasma imitans(99.7 and 99.9 % similarity, respectively). The average DNA-DNA hybridization values between strain 56A97^T and M. gallisepticum and M. imitans were 39.5 and 30 %, respectively and the Genome to Genome Distance Calculator gave results of 29.10 and 23.50 %, respectively. The 16S-23S rRNA intergenic spacer was 72-73 % similar to M. gallisepticum strains and 52.2 % to M. imitans. A partial sequence of rpoB was 91.1-92 % similar to M. gallisepticum strains and 84.7 % to M. imitans. Colonies possessed a typical fried-egg appearance and electron micrographs revealed the lack of a cell wall and a nearly spherical morphology, with an electron-dense tip-like structure on some flask-shaped cells. The isolate required sterol for growth, fermented glucose, adsorbed and haemolysed erythrocytes, but did not hydrolyse arginine or urea. The strain was compared serologically against 110 previously described Mycoplasma reference strains, showing that, except for M. gallisepticum, strain 56A97^T is not related to any of the previously described species, although weak cross-reactions were evident. Genomic information, serological reactions and phenotypic properties demonstrate that this organism represents a novel species of the genus Mycoplasma, for which the name Mycoplasma tullyi sp. nov. is proposed; the type strain is 56A97^T (ATCC BAA-1432^T, DSM 21909^T, NCTC 11747^T).

A diagnostic polymerase chain reaction for Mycoplasma iowae using primers located in the intergenic spacer region and the 23S rRNA gene

Mycoplasma iowae is primarily a pathogen of turkeys and, although uncommon, it still persists in some areas of the world, where it may cause embryo mortality and leg lesions. A species-specific diagnostic polymerase chain reaction was developed using a forward primer based in the intergenic spacer region between the 16S rRNA and the 23S rRNA ribosomal genes and a reverse primer located within the 23S rRNA gene. The polymerase chain reaction proved to be both sensitive and specific. It detected M. iowae DNA in the six reference strains of serotypes I, J, K, N, Q and R and in 28 field isolates. With the six serotypes the test detected between 1 and 5 pg of M. iowae DNA. There were no non-specific reactions with the other avian Mycoplasma species. When the closest phylogenetically related species were checked, a weak reaction with Mycoplasma muris was observed that disappeared when the annealing temperature was increased by 2°C.

Implementing best practices and validation of cryopreservation techniques for microorganisms

Authentic, well preserved living organisms are basic elements for research in the life sciences and biotechnology. They are grown and utilized in laboratories around the world and are key to many research programmes, industrial processes and training courses. They are vouchers for publications and must be available for confirmation of results, further study or reinvestigation when new technologies become available. These biological resources must be maintained without change in biological resource collections. In order to achieve best practice in the maintenance and provision of biological materials for industry, research and education the appropriate standards must be followed. Cryopreservation is often the best preservation method available to achieve these aims, allowing long term, stable storage of important microorganisms. To promulgate best practice the Organisation for Economic Development and Co-operation (OECD published the best practice guidelines for BRCs. The OECD best practice consolidated the efforts of the UK National Culture Collections, the European Common Access to Biological Resources and Information (CABRI) project consortium and the World Federation for Culture Collections. The paper discusses quality management options and reviews cryopreservation of fungi, describing how the reproducibility and quality of the technique is maintained in order to retain the full potential of fungi.

Mycoplasma gallisepticum infection in the grey partridge Perdix perdix: outbreak description, histopathology, biochemistry and antioxidant parameters

Background

The grey partridge is an important game bird in Europe that has declined considerably over the last decades. The production and release of farm-bred birds can be threatened by infectious agents. The objective of this study was to describe the outbreak, pathology, and blood and tissue biochemical responses in a flock of grey partridges naturally infected with Mycoplasma gallisepticum.

Results

Morbidity and mortality rates were 100% and 60%, respectively. Necropsy revealed an accumulation of caseous exudate within the infraorbital sinuses, tracheitis, pneumonia and airsacculitis. There were significant increases in activities of lactate dehydrogenase, creatine kinase and amylase, and levels of total protein and glucose in Mycoplasma-infected birds when compared to control. Catalase showed significantly lower activity in the heart, lungs, liver and gonads of Mycoplasma-infected birds. Glutathione-S-transferase activity was elevated in the eye and the associated infraorbital sinus and kidneys, and decreased in the liver. Decreased levels of reduced glutathione were found in the heart, kidneys, liver and gonads. The activity of glutathione reductase was lower only in the lungs. Compared to healthy birds, mycoplasmosis in the grey partridge caused significant differences in the level of lipid peroxidation in lungs and plasma (p < 0.05), while the ferric reducing antioxidant power was lower in the heart and kidneys (p < 0.01). Significant correlations among responses of the antioxidant parameters were found namely in the heart, lungs, spleen, liver and plasma. There were also numerous significant inter-tissue correlations of all the studied antioxidant parameters.

Conclusions

The present study demonstrates the high susceptibility of grey partridges to natural infection by M. gallisepticum, the severity of the disease based on histopathology, and the modulation of blood chemical profiles and oxidative stress-associated parameters in the avian hosts, thus enhancing the understanding of the pathogenesis of mycoplasmosis in birds. Moreover, the reported reference values can be useful for the evaluation of the state of health in grey partridges.

Analysis of the 16S to 23S rRNA intergenic spacer region of Mycoplasma synoviae field strains

Mycoplasma synoviae has been associated with economic loss in the chicken and turkey industries. The molecular characterization of M. synoviae at strain level allows the analysis of relationships between strains that may be valuable in epidemiological investigations. In the present study, the intergenic spacer region (ISR) between the 16S and 23S rRNA genes was examined to see whether useful information about strains could be derived. M. synoviae has two copies of this region, which may not be exactly the same (intercistronic heterogeneity). Sequencing of the ISRs of 21 M. synoviae isolates and the type strain revealed that 19 of them had such heterogeneity so DNA cloning was performed where necessary. All sequences were analysed and aligned; the percentage similarity of the DNA was calculated and a dendrogram was constructed. The length of the ISRs varied between 305 and 309 base pairs. Apart from having extra A/Ts in poly-A or poly-T regions and the presence of a few polymorphisms, the sequences of the M. synoviae strains were similar. Based on phylogenetic analysis, the strains were assigned to 10 groups-taking into account that within each group the DNA similarity was 100%, while the lowest similarity between groups was 95.8%. The results were compared with those obtained with the vlhA gene, resulting in very similar M. synoviae groups. Although the ISR could be a good target for strain typing, as has been shown by others for Mycoplasma gallisepticum, the method may be too cumbersome for routine use with M. synoviae because of complications with intercistronic heterogeneity. However, if the ISR sequence information was to be combined with other mutation detection techniques it could increase the discriminatory power.

In vitro evaluation of various antimicrobials against Mycoplasma gallisepticum and Mycoplasma synoviae by the micro-broth method, and comparison with a commercially-prepared test system

The efficacy of danofloxacin, a new quinolone antimicrobial agent, was tested in vitro by the micro-broth method with nine field strains of Mycoplasma gallisepticum (Mg) and eight of M. synoviae (Ms) and comparison was made with oxytetracycline and tylosin tartrate. The virulent S6 strain of Mg was also included for reference. All Mycoplasma strains, including a strain of Mg that was resistant to tylosin tartrate, were susceptible to danofloxacin with minimal inhibitory concentrations ranging from pound 0.008 to 0.5 microg/ml. A commercially produced test system (Sensititre), using micro-plates whose wells were predosed with antimicrobial agents and then dried, was also investigated. Results with the same three antimicrobials were in agreement with those obtained by the micro-broth method. With the exception of the tylosin resistant strain, the Mg strains were more susceptible to erythromycin than the Ms strains. Conversely, Ms strains were susceptible to apramycin, while the Mg strains appeared to be resistant.

Investigations into the survival of Mycoplasma gallisepticum, Mycoplasma synoviae and Mycoplasma iowae on materials found in the poultry house environment

Following preliminary experiments to determine suitable methods for studying mycoplasma survival, suspensions of Mycoplasma gallisepticum (four strains), Mycoplasma synoviae (two strains) or Mycoplasma iowae (two strains) were seeded onto replicate samples of cotton, rubber, straw, shavings, timber, food, feathers and human hair. The organisms were also seeded onto human skin, ear and nasal mucosa. All samples were cultured for viability after 4, 8, 12 and 24 h, and then daily up to 6 days. The identity of recovered mycoplasmas was confirmed by indirect immunofluorescence. All three Mycoplasma species survived for the longest time on feathers with M. gallisepticum surviving between 2 and 4 days and M. synoviae 2 to 3 days. The type strain of M. iowae remained viable for 5 days on feathers, while the field strain was still viable at the end of the 6-day experiment. This strain also survived for at least 6 days on human hair and several other materials. M. gallisepticum survived on human hair up to 3 days and one recent field isolate also survived in the nose for 24 h. Survival times of the organisms were generally less on other materials although M. gallisepticum could be isolated from straw, cotton and rubber samples after 2 days.

Development and evaluation of an improved diagnostic PCR for Mycoplasma synoviae using primers located in the haemagglutinin encoding gene vlhA and its value for strain typing

Using published primers, detection of Mycoplasma synoviae and strain identification using the vlhA gene sequence was attempted. However, of 21 M. synoviae strains examined, three could not be amplified, so a new reverse primer was designed with a target in the conserved region of the vlhA gene. This allowed all 21 M. synoviae strains, a further nine strains and also material from 11 swab samples from M. synoviae-positive birds, to produce a PCR product, suggesting that the method could also be suitable for clinical specimens. The protocol was then tested on the type strains of M. synoviae and the other 22 recognised avian Mycoplasma species, with amplification of M. synoviae only. Further testing demonstrated that this PCR was equally or more sensitive than other PCR tests used to detect M. synoviae. Subsequent DNA sequence analysis of the PCR product based on percent similarity and evolutionary relationship appeared to be a useful tool for strain differentiation.

Dual infection with Mycoplasma synoviae and a tenosynovitis-inducing reovirus in chickens

One group of embryonated chicken eggs was inoculated with sterile myco-plasma broth and another with a broth culture of Mycoplasma synoviae. Each group was subdivided into two and the chicks were hatched in four isolation pens. At 1 day of age one uninfected and one M. synoviae infected group were inoculated with a reovirus known to cause tenosynovitis. Birds were closely observed, and some were killed for sampling as chicks (1-5 weeks) and the remainder as adults (25-30 weeks). Clinical signs related to both organisms were seen in the dual-infected chicks and were more pronounced than in either of the corresponding single infections. There were significant weight differences between the infected and control chicks, except in single M. synoviae infection, and the mean weight of the birds with mixed infection was less than those with either single infection. Gross and histological lesions were observed in the hocks and livers of chicks in each infected group although with a higher incidence and severity in the dual-infection. Microscopic lesions were seen in the hearts of some birds in all three groups. Leg lesions associated with the reovirus infection persisted to maturity and another observation in mature, virus-infected birds was impaired egg production and fertility. M. synoviae was reisolated consistently from tracheas of single and dual-infected birds of all ages and reovirus from the tendons of inoculated birds for 4 weeks. Antibodies to both agents persisted throughout the period of the experiment.

Pathogenicity of Mycoplasma iowae for chick embryos

An investigation was carried out into the pathogenicity of four strains of Mycoplasma iowae for chick embryos. Doses ranging from approximately 10(6) to 10 colony-forming units of M. iowae per egg were inoculated via the yolk sac at 7 days of incubation. Groups of 10 or more eggs per dose were used. The eggs were incubated through to hatch, and dead embryos and hatched chicks were examined for abnormalities and mycoplasma recovery. All four strains of M. iowae caused embryo mortality but two were especially virulent - one killed all the embryos while the other killed all but one. Most deaths occurred towards the end of incubation and the main abnormalities were dwarfing and congestion. Some embryos were oedematous, especially around the head, and livers and spleens were often mustard-coloured. Hatched chicks had a low incidence of air sac lesions. Mycoplasmas, identified by immunofluorescence as M. iowae were isolated from almost every exposed embryo and chick, and from almost every site sampled. No mycoplasmas were isolated from broth-inoculated controls.

Exacerbation of Mycoplasma gallisepticum infection in turkeys by rhinotracheitis virus

Groups of 1-day-old turkey poults from a parent flock free of antibodies to turkey rhinotracheitis virus (TRTV) and the pathogenic mycoplasmas, were infected by eyedrop with virulent TRTV, with Mycoplasma gallisepticum (Mg) or with both agents together. Dual infection resulted in increased morbidity compared with those groups given single infections. The presence of the Mg in the dual infection had no apparent effect on the pathogenesis of the virus, but the virus caused the Mycoplasma to be more invasive. Mg infection caused a transient depression in TRTV ELISA antibody titres at 29 days post-inoculation. At 14 days post-infection Mg haemagglutination inhibition (HI) and rapid serum agglutination (RSA) titres were higher (P <0.01) in the mixed infection group compared with those infected with Mg alone, but there was no significant difference between ELISA antibody titres of these two groups.

Development and evaluation of a diagnostic PCR for Mycoplasma synoviae using primers located in the intergenic spacer region and the 23S rRNA gene

Mycoplasma synoviae (Ms) is an important pathogen of poultry, causing economic losses to this industry. Early and reliable diagnosis is a key to controlling the spread of this organism. In this study, a polymerase chain reaction with one primer based on the intergenic spacer region (ISR) was validated for detection of Ms. The ISR primer was paired with a general primer from within the 23S rRNA gene. The PCR primers were tested with the 22 other recognised avian Mycoplasma species to check the specificity and with 21 field isolates of Ms from various hosts and countries, and with several swab samples. The PCR appeared to be specific and sensitive. Four different sample preparation methods were compared for use in this PCR, and the amplification protocol was compared with three others, confirming the comparative sensitivity of the new PCR.

A putative transposase gene in the 16S–23S rRNA intergenic spacer region of Mycoplasma imitans

Examination of the nucleotide sequences of the 16S–23S intergenic transcribed spacer (ITS) region ofMycoplasma imitansandMycoplasma gallisepticumidentified a putative transposase gene located only in the ITS ofM. imitans, which can be used as a genetic marker to distinguish these two species. The relative size of the PCR products of the ITS region allowed a clear distinction to be made between strains ofM. imitansandM. gallisepticum, both of which could be readily discriminated from the type strains of all the other recognized avianMycoplasmaspecies. In addition, the putative transposase gene assigned in the ITS ofM. imitanswas shown to include a sequence homologous to that of the P75 gene ofM. gallisepticum. This is believed to be the first description of an insertion element in the rRNA operon region of a mycoplasma species.

Infectious agents associated with respiratory disease in pheasants

In a case-control study of the infectious agents associated with natural outbreaks of respiratory disease in pheasants, 28 batches of birds from sites affected by disease and eight batches of birds from unaffected sites were examined by six veterinary laboratories in England, Wales and Scotland, and tested for mycoplasmas, other bacteria and viruses. Sinusitis was the commonest sign of disease and was associated with Mycoplasma gallisepticum as detected by PCR in the trachea (P < 0.05) and conjunctiva (P < 0.01). Sinusitis was also associated with pasteurella cultured from the sinus (P < 0.05), antibody to avian pneumovirus (APV) (P < 0.01) and avian coronaviruses as detected by reverse-transcriptase PCR (P < 0.05); there was no association between disease and APV as detected by PCR. Avian coronaviruses were the most common infectious agents detected. They were genetically close to infectious bronchitis virus (IBV) but differed in their gene sequence from all the serotypes of IBV previously identified in domestic fowl, and serological tests with six known IBV types showed little cross reactivity. Mycoplasma species other than M gallisepticum were cultured in 18 batches of pheasants but, with the exception of Mycoplasma gallinaceum, were not associated with disease.

Detection of Mycoplasma synoviae in clinically normal pheasants

Mycoplasma synoviae was isolated from the tracheas of seven clinically normal pheasants found in the vicinity of a chicken farm infected with M synoviae, but not from 120 pheasants and partridges with respiratory disease. When specimens were examined by the polymerase chain reaction only two additional pheasants infected with M synoviae were identified, one healthy and one diseased.

Causes of mortality and non-fatal conditions among grey seals (Halichoerus grypus) found dead on the coasts of England, Wales and the Isle of Man

A survey of the diseases detectable in 141 grey seals stranded on the coasts of England and Wales away from breeding colonies was carried out between mid-1989 and early 1997. The most common fatal conditions in pups less than three weeks of age were trauma (24 per cent of deaths) and dystocia (12 per cent); in pups more than three weeks of age thy were starvation (22 per cent) and pneumonia (22 per cent); in juveniles they were drowning in fishing gear (30 per cent) and starvation (19 per cent), and in adults a variety of respiratory diseases were the most common causes of death (45 per cent). Many other diseases, both fatal and non-fatal, were recorded.

The comparative metabolism of the mollicutes (Mycoplasmas): the utility for taxonomic classification and the relationship of putative gene annotation and phylogeny to enzymatic function in the smallest free-living cells

Mollicutes or mycoplasmas are a class of wall-less bacteria descended from low G + C% Gram-positive bacteria. Some are exceedingly small, about 0.2 micron in diameter, and are examples of the smallest free-living cells known. Their genomes are equally small; the smallest in Mycoplasma genitalium is sequenced and is 0.58 mb with 475 ORFs, compared with 4.639 mb and 4288 ORFs for Escherichia coli. Because of their size and apparently limited metabolic potential, Mollicutes are models for describing the minimal metabolism necessary to sustain independent life. Mollicutes have no cytochromes or the TCA cycle except for malate dehydrogenase activity. Some uniquely require cholesterol for growth, some require urea and some are anaerobic. They fix CO2 in anaplerotic or replenishing reactions. Some require pyrophosphate not ATP as an energy source for reactions, including the rate-limiting step of glycolysis: 6-phosphofructokinase. They scavenge for nucleic acid precursors and apparently do not synthesize pyrimidines or purines de novo. Some genera uniquely lack dUTPase activity and some species also lack uracil-DNA glycosylase. The absence of the latter two reactions that limit the incorporation of uracil or remove it from DNA may be related to the marked mutability of the Mollicutes and their tachytelic or rapid evolution. Approximately 150 cytoplasmic activities have been identified in these organisms, 225 to 250 are presumed to be present. About 100 of the core reactions are graphically linked in a metabolic map, including glycolysis, pentose phosphate pathway, arginine dihydrolase pathway, transamination, and purine, pyrimidine, and lipid metabolism. Reaction sequences or loci of particular importance are also described: phosphofructokinases, NADH oxidase, thioredoxin complex, deoxyribose-5-phosphate aldolase, and lactate, malate, and glutamate dehydrogenases. Enzymatic activities of the Mollicutes are grouped according to metabolic similarities that are taxonomically discriminating. The arrangements attempt to follow phylogenetic relationships. The relationships of putative gene assignments and enzymatic function in My. genitalium, My. pneumoniae, and My. capricolum subsp. capricolum are specially analyzed. The data are arranged in four tables. One associates gene annotations with congruent reports of the enzymatic activity in these same Mollicutes, and hence confirms the annotations. Another associates putative annotations with reports of the enzyme activity but from different Mollicutes. A third identifies the discrepancies represented by those enzymatic activities found in Mollicutes with sequenced genomes but without any similarly annotated ORF. This suggests that the gene sequence is significantly different from those already deposited in the databanks and putatively annotated with the same function. Another comparison lists those enzymatic activities that are both undetected in Mollicutes and not associated with any ORF. Evidence is presented supporting the theory that there are relatively small gene sequences that code for functional centers of multiple enzymatic activity. This property is seemingly advantageous for an organism with a small genome and perhaps under some coding restraint. The data suggest that a concept of "remnant" or "useless genes" or "useless enzymes" should be considered when examining the relationship of gene annotation and enzymatic function. It also suggests that genes in addition to representing what cells are doing or what they may do, may also identify what they once might have done and may never do again.

Identification of Mycoplasma iowae by colony immunoblotting utilizing monoclonal antibodies

The utility of monoclonal antibody Mab-2C in identification of Mycoplasma iowae (MI) by colony immunoblotting technique was explored. Colony immunoblots of reference MI strains, field isolates, and mycoplasmas recovered from experimentally inoculated turkey embryos were probed with Mab-2C. The monoclonal antibody identified colonies of all the MI isolates tested and did not cross-react with colonies of M. gallisepticum, M. synoviae, or M. meleagridis. In western immunoblots of 22 MI field isolates, Mab-2C showed immunoreactivity with an antigen of approximately 45 kD molecular weight. No phenotypic variation of the epitope recognized by Mab-2C was observed in colony immunoblots of MI colonies. The monoclonal antibody reported here can be used for identification of MI colonies by a simple and rapid colony immunoblot method.

Pathogenicity and cytadherence of Mycoplasma imitans in chicken and duck embryo tracheal organ cultures

Two strains of the avian organism Mycoplasma imitans were examined for pathogenicity and cytadherence in chicken and duck embryo tracheal organ cultures, and a virulent strain of the related pathogen Mycoplasma gallisepticum was included for comparison. All consistently cause ciliostasis in tracheal explants from both hosts, and examination of infected tissues by immunofluorescence and transmission electron microscopy demonstrated that M. imitans proliferated on the epithelial surface and adhered to the respiratory epithelium by means of its terminal tip structure in the same manner as M. gallisepticum. These observations endorse the striking phenotypic similarities between M. imitans and M. gallisepticum and suggest that M. imitans may have pathogenic potential in vivo.

A rapid method for detection of N-acetylglucosaminidase-type chitinase activity in crossed immunoelectrophoresis and sodium dodecyl sulfate-polyacrylamide gel electrophoresis gels using 4-methylumbelliferyl-N-acetyl-D-glucosaminide as substrate

A method for the detection of N-acetylglucosaminidase (GlcNAcase) activity has been developed by using 4-methyl-umbelliferyl-N-acetyl-D-glucosaminide (4-MU-GlcNAc) as substrate in crossed immunoelectrophoresis (CIE) and sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) gels. Visualization of the reaction with a 366 nm ultra-violet light is possible in approximately 30 min. The method is fast and sensitive in comparison with previous methods. The same band as in SDS-PAGE, showing both GlcNAcase and chitinase activity, was found in the present study; we therefore conclude that this method is also useful in a GlcNAcase-type chitinase assay.

Typing of strains from a single-source outbreak of Pseudomonas pickettii

Plasmid profiles, genome restriction fragment polymorphisms, carbohydrate oxidation-fermentation reactions, methylumbelliferyl substrate hydrolysis patterns, antimicrobial susceptibilities, and results obtained with the Biolog GN biochemical substrate kit were used to type 19 common-source, but mixed-biotype, outbreak strains and one epidemiologically distinct strain of Pseudomonas pickettii. Biotyping with conventional and methylumbelliferyl substrates failed to distinguish between strains. Plasmid profile testing was found to be inconsistent and not reproducible. The Biolog GN kit allowed greater strain differentiation than restriction fragment polymorphism did (12 biotypes versus 5 biotypes); antimicrobial susceptibility testing yielded 4 biotypes, and oxidation-fermentation tests gave 3 biotypes. Oxidation-fermentation results were consistent with restriction fragment polymorphs in all but 1 of the 20 strains tested. For ease of typing, comprehensive typeability, and reproducibility, oxidation-fermentation tests should be performed initially and followed if necessary by restriction fragment polymorph analysis for the elucidation of P. pickettii infection outbreaks.

Evaluation of two fluorogenic assays for identification of Streptococcus species isolated from bovine mammary glands

Liquid and agar assays that utilized 4-methylumbelliferyl-conjugated beta-D-glucuronide, beta-D-galactoside, or N-acetyl-beta-D-glucosaminide, and agglutination by Dolichos biflorus lectin were evaluated for identification of Streptococcus species isolated from bovine mammary glands. A greater number of Streptococcus uberis isolates were negative for N-acetyl-beta-D-glucosaminidase by the liquid assay compared with the agar assay. Enzyme profiles for Streptococcus dysgalactiae were similar by both assays. Streptococcus dysgalactiae was the only species that agglutinated when mixed with lectin from D. biflorus. Most Streptococcus agalactiae isolates were positive for beta-D-glucuronidase and beta-D-galactosidase by both assays. Two Streptococcus equinus strains had negative enzyme profiles by the liquid assay; however, both strains had enzyme profiles consistent for S. equinus by the agar method. Incorporation of 4-methylumbelliferyl-conjugated substrates into trypticase soy agar did not appear to alter agar characteristics and eliminated aliquoting substrates and inoculating tubes. More than one enzyme profile was produced per Streptococcus species or serogroup by both methods. However, some profiles were similar between species, which hindered accurate identification of Streptococcus species.

Rapid identification of Salmonella from poultry meat products by using 'Mucap Test'

A study was made in order to improve a new Salmonella identification test (Mucap Test) in which umbelliferone is released, giving a blue fluorescent light under a Wood lamp, after contact with Salmonella colonies. The study concerned 354 colonies, previously isolated from 55 poultry meat samples. Two enrichment media [Tetrathionate Bile Broth (TBB) and Rappaport Vassiliadis (RV)] and two isolation media [Brilliant Green Agar (BGA) and Desoxycholate Agar (DA)] were used, and the results of the test obtained respectively with each association were compared. The sensitivity was consistently good, but the specificity of the test was generally poor. The best association seemed to be RV/DA which gave 85% specificity, against 39% for TBB/BGA, 58% for TBB/DA, and 77% for RV/BGA. The predominant genera responsible for false-positive results were Pseudomonas and Proteus Providencia.

Rapid identification of Branhamella catarrhalis with 4-methylumbelliferyl butyrate

Branhamella catarrhalis can be distinguished from Neisseria spp. by the presence of butyrate esterase. This enzyme can be rapidly detected when 4-methylumbelliferyl butyrate is used as the substrate. All B. catarrhalis strains tested gave a positive fluorescence reaction within 5 min, while Neisseria spp. remained negative, even after 18 h of incubation.

Rapid biochemical tests for the identification of groups A, B, C, F, and G streptococci from throat cultures

A test employing three fluorogenic 4-methylumbelliferyl substrates and the lectin of Dolichos biflorus was developed for the identification of beta-hemolytic streptococcal colonies associated with throat cultures. This non-serological method is unique in that it permits the accurate identification of groups C, F, and G streptococci, as well as groups A and B streptococci. The method is rapid, simple, and specific and appears to be a useful means to identify groups A, B, C, F, and G streptococci.

Detection of mixed Mycoplasma species

Immunofluorescence can be used to demonstrate mixed species within a mycoplasma culture; however, it may fail to do so if one species is present in very low numbers. To enhance the detection of minor components in such mixtures, a technique was developed, based on the growth inhibition test, whereby the growth of the major component in a mixed culture was inhibited, thus permitting the minor component to emerge. The method was applied to 67 field isolates from chickens and turkeys, which had been examined by immunofluorescence and were thought to contain only one mycoplasma species. Of these, 26 cultures were found to be mixtures, and in some instances the pathogenic species Mycoplasma gallisepticum and M. meleagridis were revealed.

Rapid detection of yeast enzymes by using 4-methylumbelliferyl substrates

In a preliminary study with a limited number of isolates, the usefulness of 17 4-methylumbelliferyl substrates for identifying yeast isolates was investigated. Substrates to detect acid phosphatase, glucosidase, and pyrophosphate diesterase showed promise.