Retention of Acholeplasma laidlawii by Sterile Filtration Membranes: Effect of Cultivation Medium and Filtration Temperature

This experimental study compares cell size, zeta potential, and the ability to penetrate tailor-made size exclusion membrane filters of mycoplasma Acholeplasma laidlawii cultivated in five different cultivation media. The influence of relevant filtration process parameters, in particular transmembrane pressure and filtration temperature, on their respective retention was tested. The impact of the filtration temperature was further evaluated for the Gram-negative bacteria species Brevundimonas diminuta, the Gram-positive bacteria species Staphylococcus epidermidis, the Pseudomonas phage PP7, and the mycoplasma species Mycoplasma orale The findings were correlated to the different mechanical properties of the particles, especially also with respect to the different bacterial cell envelopes found in those species. This study suggests that mycoplasma, surrounded by a flexible lipid bilayer, are significantly susceptible to changes in temperature, altering the stiffness of the cell envelope. Mycoplasma retention could thus be increased significantly by a decreased filtration temperature. In contrast, Gram-negative and Gram-positive bacteria species, with a cell wall containing a cross-linked peptidoglycan layer, as well as bacteriophages PP7 exhibiting a rigid protein capsid, did not show a temperature-dependent retention within the applied filtration temperatures between 2 and 35 °C. The trends of the retention of A. laidlawii with increasing temperature and transmembrane pressure were independent of cultivation media. Data obtained with mycoplasma M. orale suggest that the trend of mycoplasma retention at different filtration temperatures is also independent of the membrane pore size and thus retention level.LAY ABSTRACT: Media in biopharmaceutical processes are sterile-filtered to prevent them from bacterial contamination. Mycoplasma represent a relevant class of bacteria. In this publication it is shown that mycoplasma cell size depends on the media they are cultivated in. Membranes used for sterile filtration retain bacteria predominantly by size exclusion. Thus, an altered cell size can result in different retention values. Another characteristic of mycoplasma is the flexible lipid bilayer and the absence of a rigid cell wall. The lipid bilayer can undergo a phase transition from a gel to a liquid-crystal phase at a certain temperature, which makes it stiffer at lower temperatures. A higher stiffness can result in higher retention values during filtration, as the deformability of the mycoplasma cell is lower and the cell does not squeeze through the membrane pores.

ABBREVIATIONS

ALCM: A. laidlawii culture medium; ASTM: American Society for Testing and Materials; ATCC: American Type Culture Collection; CFU/mL: colony-forming units per milliliter; DLS: Dynamic light scattering; LRV: Log reduction value; PES: Polyethersulfone; PFU/mL: Plaque-forming units per milliliter; PSD: Particle size distribution; PVP: Polyvinylpyrrolidone; SDS: Sodium dodecyl sulfate; SEM: Scanning electron microscopy; SLB: Saline lactose broth; TMP: Transmembrane pressure; TSB: Tryptic soy broth.

Mycoplasma Clearance and Risk Analysis in a Model Bioprocess

Mycoplasmas are a type of bacteria that lack cell walls and are occasional cell culture contaminants. In a biotechnology setting, because they can pass through 0.2 μm filters, mycoplasmas could pose a potential patient safety hazard if undetected contaminants from the production culture were not completely removed by downstream biotechnology manufacturing. In this study we investigated the ability of typical commercial monoclonal antibody purification operations to clear and kill mycoplasmas, using Acholeplasma laidlawii as a model organism. Our spike/removal studies have shown that protein A column chromatography clears about 4-5 log₁₀ Column regeneration effectively prevents A. laidlawii column carryover between chromatography runs. Moreover, low-pH hold steps, typically implemented after protein A purification, effectively kill A. laidlawii using either pH 3.8 glycine or acetate solutions (LRV ≥5.30 and ≥4.57, respectively). Solvent/detergent treatment, used in some processes instead of low-pH hold, also completely kills highly concentrated A. laidlawii (LRV ≥5.95).LAY ABSTRACT: Biotechnology medicines need to be free from contaminating microorganisms such as mycoplasmas, a type of bacteria that can cause disease in humans (e.g., walking pneumonia). Here we show that some monoclonal antibody manufacturing steps can effectively clear and/or kill Acholeplasma laidlawii, a model mycoplasma species used in our study. This provides an additional level of safety assurance of biotechnology medicines for patients.

The Development of a Microbial Challenge Test with Acholeplasma laidlawii To Rate Mycoplasma-Retentive Filters by Filter Manufacturers

Mycoplasma are bacteria that can penetrate 0.2 and 0.22 μm rated sterilizing-grade filters and even some 0.1 μm rated filters. Primary applications for mycoplasma filtration include large scale mammalian and bacterial cell culture media and serum filtration. The Parenteral Drug Association recognized the absence of standard industry test parameters for testing and classifying 0.1 μm rated filters for mycoplasma clearance and formed a task force to formulate consensus test parameters. The task force established some test parameters by common agreement, based upon general industry practices, without the need for additional testing. However, the culture medium and incubation conditions, for generating test mycoplasma cells, varied from filter company to filter company and was recognized as a serious gap by the task force. Standardization of the culture medium and incubation conditions required collaborative testing in both commercial filter company laboratories and in an Independent laboratory (Table I). The use of consensus test parameters will facilitate the ultimate cross-industry goal of standardization of 0.1 μm filter claims for mycoplasma clearance. However, it is still important to recognize filter performance will depend on the actual conditions of use. Therefore end users should consider, using a risk-based approach, whether process-specific evaluation of filter performance may be warranted for their application.

LAY ABSTRACT

Mycoplasma are small bacteria that have the ability to penetrate sterilizing-grade filters. Filtration of large-scale mammalian and bacterial cell culture media is an example of an industry process where effective filtration of mycoplasma is required. The Parenteral Drug Association recognized the absence of industry standard test parameters for evaluating mycoplasma clearance filters by filter manufacturers and formed a task force to formulate such a consensus among manufacturers. The use of standardized test parameters by filter manufacturers, including the preparation of the culture broth, will facilitate the end user's evaluation of the mycoplasma clearance claims provided by filter vendors. However, it is still important to recognize filter performance will depend on the actual conditions of use; therefore end users should consider, using a risk-based approach, whether process-specific evaluation of filter performance may be warranted for their application.

Taxonomic status of the agent of cereals pale-green dwarf and proposition of founding in the class of Mollicutes, of the order III Acholeplasmatales, family I Acholeplasmataceae, genus II Pluraplasma gen. nov., and its first species Pluraplasma granulum sp. nov

The paper includes the data concerning the taxonomic status of the agent of cereals pale-green dwarf (ACPGD) which has been defined as the phytopathogenic variant of the mollicute Acholeplasma laidlawii and called A. laidlawii var. granulum. Since besides phytopathogenicity ACPGD has such fundamental differences from A.laidlawii as: a very large genome of 2200 thousand pairs of nucleotides (t.p.n.) to 2310 t.p.n. that practically equals a sum of genomes of A. laidlawii (1600 t.p.n.) and phytoplasmas (710 t.p.n.); two forms of DNA-dependent RNA-polymerase (one form functions in A. laidlawii); a capacity to form extracellular fructosobisphos-phatase which looks like its hypothetical phylogenetic precursor a bacteria Bacillus subtilis; availability of numerous fermentative activities which are absent in acholeplasmas; peculiar relation to sterols availability in nutrient media that is not characteristic of all the known acholeplasmas; extremely rich, as to quantity and quality, composition of antigens to react almost homologously with antibodies to representatives of Acholeplasma genus and separate species of Mycoplasma genus; great similarity (above 88 %) of sequences of 16S rRNA of ACPGD and representatives of Phytoplasma genus and other properties described in the paper, so it is concluded, that proceeding from its characteristics, ACPGD cannot be referred to either of the existing genera of the Mollicules class, because according to all its features this mollicute is a transition form of the microorganism, it is the hitherto unknown chain between these genera of mollicutes and sporiferous bacteria, ACPGD is a probable representative of mollicute precursor with genome of about 1600 t.p.n. and, first of all, of genera Acholeplasma and Phytoplasma which arised as a result of the evolutionary splitting of its genome. On this basis, it is recommended to found for ACPGD in the Mollicutes class, order III Acholeplasmatales, family I Acholeplasmataceae, a new genus II Pluraplasma gen. nov. and its first species Pluraplasma granulum sp. nov., the strain 118 being its typical representative.

[On the nature of the pathogen of pale-green dwarfism in cereals]

The paper presents more precise data concerning optimal temperature demands to growth of white-yellow dwarfness of cereals (WYDC) identified before as Acholeplasma laidlawii var. granulum, its relation to sterols and genome properties was determined using pulse-electrophoresis. It was established that the agent strains 84 and 118, characterized by phytopathogenicity, grew most intensively at 32 degrees C; they behaved as mesoplasmas but, as it had been found, they were capable to synthesis of carotenoids and displayed close serologic affinity for A. laidlawii PG8. That is, the above strains are typical acholeplasmas capable to live in leafhoppers which carry a disease and in cereals plants and cause a disease with typical symptoms of "yellows" in the latter. Molecular weight of the strain 84 genome was 2200 t.p.n. (GC = 33 mol %); in strains 118 it was 2310 t.p.n. (GC = 34.2 mol %). Allowing for the fact that molecular weight of genome of A. laidlavii var. granulum is almost by 1/3 (1600 + 710 t.p.n.) more than that of A. laidlawii PG8 genome, the authors think that the agent of WYDC is the evolution precursor (or one of precursors) which initiated the Acholeplasma and Phytoplasma genera as a results of splitting of their genomes.

[Change in lectin specificity of winter wheat seedlings in the course of infection with mycoplasms]

The activity of soluble lectins in leaves and roots of seedlings of winter wheat (Triticum aestivum L.) cultivar Mironovskaya 808 increased 1 day and 2 days, respectively, after infection with the mycoplasma Acholeplasma laidlawii 118. Analysis of acid-soluble proteins of wheat leaves by PAGE revealed the appearance of 22- and 20-kDa polypeptides, the disappearance of a 14-kDa polypeptide, and an increase in the content of polypeptides with molecular weights of 76, 48, 25, and 18 kDa. The 18-kDa polypeptide is a subunit of wheat germ agglutinin. A change in the activity of lectins may be a nonspecific response of plants to infection with the pathogen.

Colistin sulfate as a suitable substitute of thallium acetate in culture media intended for mycoplasma detection and culture

Thallium acetate in concentrations of 500 to 1000 mg/l is tolerated in the culture by the most mollicutes of the orders Mycoplasmatales and Acholeplasmatales and by this reason it is added in the culture media as a selective element for the detection and propagation of mycoplasmas and acholeplasmas. Because of the high toxicity of thallium acetate and its accumulation in the environment, thallium acetate is not biodegradable, an alternative was searched. The results and analysis of tests with nine mollicute species are presented here. It is recommended to replace thallium acetate in the formulations where it is used and colistin sulfate is proposed as its substitute.

Development and qualification of a novel virus removal filter for cell culture applications

Commercial bioreactors employing mammalian cell cultures to express biological or pharmaceutical products can become contaminated with adventitious viruses. The high expense of such a contamination can be reduced by passing all gases and fluids feeding the bioreactor through virus inactivation or removal steps, which act as viral barriers around the bioreactor. A novel virus barrier filter has been developed for removing viruses from serum-free cell culture media. This filter removes the 20 nm minute virus of mice by >3 log reduction value (LRV), the 28 nm bacteriophage PhiX174 by >4.5 LRV, the mycoplasma Acholeplasma laidlawii by > or =8.8 LRV, and the bacteria Brevundimonas diminuta by > or =9.2 LRV. Robust removal occurs primarily by size exclusion as demonstrated over a wide range of feedstocks and operating conditions. The filtered media are indistinguishable from unfiltered media in growth of cells to high densities, maintenance of cell viability, and productivity in expressing protein product. Insulin and transferrin show high passage through the filter. The virus barrier filter can be autoclaved. The relatively high membrane permeability enables the use of a moderate filtration area.

A polymerase chain reaction based method for detecting Mycoplasma/Acholeplasma contaminants in cell culture

A detection system that utilizes a primer mixture in a nested polymerase chain reaction for detecting Mycoplasma contaminants in cell cultures is described. Primers were designed to amplify the spacer regions between the 16S and 23S ribosomal RNA genes of Mycoplasma and Acholeplasma. This detection system was able to detect 20-180 colony forming units per milliliter of sample. Eight commonly encountered Mycoplasma and Acholeplasma contaminants, which include Mycoplasma (M.) arginini, M. fermentans, M. hominis, M. hyorhinis, M. orale, M. pirum, M. salivarium, and Acholeplasma laidlawii, were consistently amplified. Mycoplasma contaminants generated a single DNA band of 236-365 base pairs (bp), whereas A. laidlawii produced a characteristic two-band pattern of 426 and 219 bp amplicons. Species identification could be achieved by size determination and restriction enzyme digestion. Minor cross-reactions were noted with a few closely related gram positive bacteria and DNA from rat cell lines. A Mycoplasma Detection Kit for detecting Mycoplasma contaminants in cell cultures has been developed based on this approach.

[Effect of mycoplasma contamination of the human uterine leiomyosarcoma cell line SK-UT-1B on karyotype structure]

The karyotypic variability has been investigated for human uterine leiomyosarcoma cell line SK-UT-1B, cultivated for 30-90 days after contamination with Acholeplasma laidlawii, strain PG-8. The character of cell distribution for chromosome number gradually changes in contaminated cells, comparatively to the control, with the lengthening of the term of contamination. So, in 30 days the analysed distributions do not differ in the experimental and in the control variants, the modal number of chromosomes being equal to 46. In 60 days the frequency of cells with modal number of chromosomes have a tendency to decrease, and the range of variability in the number of chromosomes tend to increase. In 90 days, the frequency of cells with modal number of chromosomes decreases significantly, and the range of variability on the number of chromosomes increases significantly. The number of chromosomal aberrations gradually increases in contaminated cells, as compared to the control, with the lengthening of the term of contamination. So, in 30 days the number of chromosomal aberrations does not increase, only the number of dicentrics (telomeric associations) has the tendency to increase. In 60 days, the number of chromosomal aberrations, mainly dicentrics, increases significantly. In 90 days, the number of chromosomal aberrations increases significantly, including both dicentrics and chromatid breaks. The possible reasons of the observed character of karyotypic variability is discussed. Our previous results make it possible to suppose that the increase in the number of dicentrics in "markerless" line SK-UT-1B with long term contamination may be an additional evidence on the role of dicentrics in cell adaptation to in vitro conditions in such lines.

Evaluation of current sterility tests for human live viral vaccines

Current sterility tests for human viral vaccines were evaluated. A total of 43 lots of bulk suspension of live viral vaccines (measles, mumps, rubella and oral poliomyelitis) produced by six manufacturers in Japan were evaluated for bacteriostatic and mycoplasmastatic activities. Some of them showed fairly high bacteriostatic and mycoplasmastatic activities, due to antibiotics added during vaccine production. It was concluded that the current sterility test for mycoplasmas is not reliable to detect viable mycoplasmas in live viral vaccines.

Breeder turkey hens seropositive and culture-negative for Mycoplasma synoviae

Four flocks of clinically normal turkey breeder hens were shown to have suspect and positive Mycoplasma synoviae (MS) hemagglutination-inhibition (HI), enzyme-linked immunosorbent assay, and, in some cases, serum plate agglutination serology in the absence of MS isolation. In all cases, HI serology for Mycoplasma gallisepticum (MG) and M. meleagridis was negative. Acholeplasma laidlawii was isolated from some hens in each of these MS-seropositive culture-negative flocks. Immunoblotting was used to help determine if this positive MS serology was a result of cross-reactive antibodies to A. laidlawii or to some other Mycoplasma species. When sera from two of the flocks were reacted with MS antigen in immunoblotting, a strong and characteristic MS immunoblot profile was seen. Immunoblotting gave no evidence of a strong antibody response to A. laidlawii, M. iowae, or MG. This suggests the presence (or earlier presence) of MS in these flocks that is difficult to isolate by routine methods. Furthermore, this work shows that immunoblotting can be an important tool in the diagnosis of poultry diseases.

Effects of age, environmental temperature and relative humidity on the colonization of the nose and trachea of calves by Mycoplasma spp

Nasal and tracheal swabs sequentially collected from three groups of eight calves between the ages of 1 and 98 days indicated that the nose and trachea were colonized by Mycoplasma spp. during the first weeks of life. Over 92% of all calves harboured Mycoplasma spp. in their noses when they were 2 weeks old, the rate of recovery falling gradually thereafter. The peak period of recovering mycoplasmas from the noses and tracheas of calves was at 6 weeks old. M. bovirhinis, M. arginini and Acholeplasma laidlawii predominated in the nose while M. dispar and M. bovirhinis predominated in the trachea. There was no association between rates of isolation and clinical signs of respiratory disease. There were no significant differences between the frequencies of isolation of Mycoplasma spp. from groups of calves kept under different environmental temperatures and relative humidities.

Evaluation of a digitonin disk assay to discriminate between acholeplasma and mycoplasma isolates from bovine milk

A study was undertaken to evaluate effectiveness of a digitonin disk inhibition test to discriminate between Acholeplasma laidlawii and Mycoplasma sp. isolated from bovine milk. The test measured zone diameters of growth inhibition surrounding a digitonin-containing disk on solid medium. Zones of inhibition for 20 isolates of A. laidlawii, ranging from 8-14 mm, did not overlap those of 261 isolates of Mycoplasma sp., ranging from 16 to 38 mm. Examination of variation in zone diameters for M. bovis found that inhibition was not appreciably affected by agar dehydration. Zones of inhibition increased with increasing dilutions of stock culture and decreased with increasing incubation time. Analysis of variance and Fisher's least significant difference test of logn zone diameters revealed that differences in mean logn zone diameters were different at the 0.01 level of significance between some of the six species of mycoplasma examined, indicating that growth among some species of mycoplasma was effected differently by digitonin. The digitonin test was found to clearly discriminate between A. laidlawii and Mycoplasma sp. indicating that the test would be useful as a practical screening test of individual-cow and bulk tank milk for mycoplasmas.

Comparison of two methods for detection of mollicutes (Mycoplasmatales and Acholeplasmatales) in cell cultures in the Netherlands

A total of 1949 cell cultures was tested for contamination with mollicutes by cultivation on and in mycoplasma media, 25.7% of the cell cultures was positive, 243 strains of Mycoplasma hyorhinis were isolated. Furthermore, mainly M. arginini and M. orale were detected, less often Acholeplasma laidlawii, M. fermentans and M. pneumoniae. Optimal conditions for isolation were discussed. About one third of 217 hybridoma cultures and two third of 57 myeloma cultures proved to be contaminated, all with M. hyorhinis. A DNA fluorochrome staining method (DAPI-test) was compared to cultivation for testing 1039 cell cultures. The efficiency of the DAPI-test could be estimated to be about 96% that of cultivation about 89%, but cultivation is more specific. The highest assurance is obtained when both methods are applied.

Isolation and pathogenicity of mycoplasmas from geese

Several mycoplasma isolation trials were performed on infertile goose eggs and goose embryos which died during incubation, as well as on geese of different ages. A total of 43 out of 110 goose eggs proved to be contaminated by mycoplasmas. Upon autopsy of birds which laid positive eggs, lesions were observed in the airsacs. Mycoplasmas could be isolated from their air sacs and oviduct. Four out of 15 strains examined biochemically and serologically with antisera prepared against all known avian mycoplasma species were identified as Acholeplasma laidlawii and A. axanthum, respectively. Two strains proved to be glucose-positive and arginine-negative and 9 were glucose-negative but arginine-positive. Some strains caused 50-80% mortality among embryos inoculated intra-yolk-sac at 12 days. In goslings inoculated at the age of 3 days with these strains, we observed fibrinous airsacculitis and peritonitis. By inoculating laying geese with one of the strains, we demonstrated decreasing egg production, increasing early-embryo mortality and egg transmission of mycoplasmas.

Mycoplasmal infection of insect cell cultures

Twenty-five cell cultures of three insect orders from eight laboratories were tested for mycoplasmal infection. Acholeplasma laidlawii was detected in one culture, an incidence of 4.0%. A. laidlawii, Mycoplasma orale, M. arginini, but not M. hyorhinis, could establish infections of drosophila Dm-1 cell cultures at 25 degrees C. In prospective studies, drosophila Dm-1 cultures were intentionally infected with broth-propagated A. laidlawii and M. hyorhinis. M. hyorhinis did not grow and was eliminated from the Dm-1 cultures during consecutive passages. A. laidlawii grew without obvious cytopathic effects during six weekly passages; titers of over 10(7) CFU/ml were recorded at Passages 2 and 5 (p2 and p5). Minimal cell culture infectious doses were also determined during these studies. 0.1 milliliter cell samples were inoculated into Leighton tubes containing either fresh M1A culture medium or 3T6 indicator cells in McCoy's 5a medium. After 4 d of incubation at 25 and 37 degrees C, respectively, the cover slips were stained by DNA fluorochrome Hoechst 33258 (A. laidlawii) or by specific fluorescein-conjugated antiserum (M. hyorhinis). At p2 with both mycoplasma species, the procedure using M1A medium and incubation at 25 degrees C without 3T6 cells was inferior to indicator cells. In five of six experiments at least a two-log higher titer of mycoplasmas was needed to be detected with M1A and 25 degrees C. At p5 no difference could be found. Uridine phosphorylase assays of Dm-1 cultures infected with A. laidlawii, M. hyorhinis, M. orale, and M. arginini gave clearly positive results only with A. laidlawii. The ratio of incorporated uridine to incorporated uracil method yielded false positives with two drosophila cell lines. Suggestions for assay of mycoplasmas in invertebrate cell cultures are given.

Isolation of acholeplasmas and a mycoplasma from vegetables

The isolation of Mollicutes from food has not been reported. To isolate Mollicutes in the presence of high levels of unwanted bacteria, we first incubated fresh vegetables in liquid culture media containing lysozyme, ampicillin, and thallous acetate. Culture fluids were than separated from the vegetable samples, subjected to one freeze-thaw cycle, and passed through a filter of 0.4-micron porosity. Filtered samples were cultured in SP4 medium and in a conventional medium containing horse serum. With this procedure 21 acholeplasma isolations representing three species were obtained from endive, broccoli, and kale. Of 35 food samples tested, 11 were positive for acholeplasmas; acholeplasmas isolated from 6 of these samples were recovered only in SP4 medium. In seven single vegetable samples, two or more Acholeplasma spp. were isolated. A. laidlawii was isolated from all three vegetables and A. axanthum was found in broccoli and kale. Four isolates were serologically identified as A. oculi. Mycoplasma verecundum was the only Mycoplasma species recovered. Several isolates could not be typed serologically, as they reacted with antisera to both A. morum and A. hippikon. these isolates may include new Acholeplasma spp.

Bovine genital mycoplasmosis

Infection, lesions and clinical significance of Acheloplasmas, Mycoplasma bovis and Mycoplasma bovigenitalium in genital disease of cattle are described. A more detailed account is given of ureaplasma infections. Acute and chronic forms of granular vulvitis in both field and experimental disease are described as well as the role of the organism in abortion. Recovery rates of ureaplasma and mycoplasma from semen and preputial washings in bulls are outlined and their significance in disease is discussed. There are problems in differentiating pathogenic from nonpathogenic isolates. Methods are being developed to treat semen for these organisms. This paper provides a concise summary of clinical and microbiological aspects of bovine genital mycoplasmosis.

[Biochemical and serologic study of Acholeplasmae isolated from monkeys]

Biochemical and serological properties of mycoplasmas isolated from the blood, feces and parenchymatous organs of monkeys have been studied to determine their species. It was established that the isolated strains belong to the family Acholeplasmatoceae. The study of their biochemical properties in different tests has revealed the presence of 5 biochemically heterogeneous groups. Their serological properties suggest that 13 out of 45 strains are identical to the reference strain of A. laidlawii A, and all other strains have been classified as new Acholeplasma species which have never been isolated from monkeys before.

[Use of the growth inhibition test, the CFT, and the agar gel diffusion precipitation test to identify mycoplasmae isolated from monkeys]

The data are presented on comparative evaluation of the growth inhibition test (GIT), the diffuse precipitation test in agar gel (DPTAG) and the complement fixation test (CFT) in the identification of Mycoplasma isolated from monkeys. The results obtained in the study of 4 Mycoplasma strains from the internal organs of monkeys in the CFT and the DPTAG with hyperimmune rabbit sera provided by Microbiological Associates, Bethesda, Maryland, USA, allowed these Mycoplasma to be identified as M. laidlawii (l 6916, p 6240 and M 6802) and M. hominis (C 7034), which was confirmed by the study of the biological properties of these strains and in the GIT. The CFT and the DP-TAG, equally to the GIt and other serological tests, can be used for identification of newly isolated Mycoplasma strains.

A severe outbreak of bovine mastitis assoicated with Mycoplasma bovigenitalium and Acholeplasma laidlawii

An outbreak of clinical mastitis is described in which 75 cows of a herd of 200 Friesian cows were affected in one or more quarters over a period of three months. Sixty animals failed to return to normal despite various intramammary and systemic antibiotic treatments. Heifers, dry cows and lactating animals were affected. The milk of 15 out of 53 animals tested yielded mixed cultures of Mycoplasma bovigenitalium and Acholeplasma laidlawii. Thirteen of 34 sera showed evidence of antibodies to A laidlawii.

Isolation of Mycoplasma arginini from swine and from a swine waste disposal system

Mycoplasma arginini was isolated from the pharynges and tonsils of 4 of 6 swine necropsied during an epizootic of respiratory tract diseases and lameness. The organism was also isolated from 2 of 16 asymptomatic swine examined in the same herd approximately 10 months after the epizootic. In addition, M arginini, Acholeplasma laidlawii, and other acholeplasmas were isolated from recycled effluent of an anaerobic lagoon used for disposal of waste from the swine herd. This observation represents the 1st report of a Mycoplasma species isolated from a lagoon or sewage system. The pathogenicity of a strain of M arginini isolated during the epizootic was examined by inoculating young swine intranasally, intratracheally, intravenously, and intraperitoneally. The agent colonized in the pharynges of 2 pigs inoculated intranasally, but did not produce overt signs of clinical disease. Although neutralizing antibodies to M arginini were not detected, 1 animal that had been infected naturally and 2 that had been inoculated intravenously did develop complement-fixing antibodies. The findings indicate that M arginini can colonize in the nasal and pharyngeal mucosae of swine, but that it is not highly pathogenic for these animals.

Spread and control of mycoplasmal infection of cell cultures

Environmental sampling was performed during trypsinization and passage of 3T-6 cell cultures that contained a mean of 4.3 X 10(7) colony forming units (CFU) per ml supernatant of A. laidlawii. The lip of the culture flask and the outside of the used pipet were always heavily contaminated. The outside of the culture flask (3/7), the work surface (8/12) and the outside of a pan of disinfectant (4/5) were regularly contaminated with mycoplasmas. Airborne mycoplasmas were detected eight of 32 times (25%) by settling plates; simultaneous forced-air samplers by two different methods were always negative. The technician's hands were contaminated two of 15 samples. When hands were contaminated, more contamination was detected in the environment. Droplets of A. laidlawii and M. orale inoculated onto work surfaces survived drying for a minimum of 3 days, even in laminar airflow cabinets. Twenty-five of 31 (80.6%) cell culture technicians carried M. salivarium in their throats; only two carried M. orale. It is concluded that mycoplasma-infected clltures are the most common source of further infection. Recommendations for prevention and control of mycoplasmal infection are listed.

Infectious bovine keratoconjunctivitis: experimental induction of infection in calves with mycoplasmas and Moraxella bovis

Eyes of 14 calves were exposed by conjunctival instillation to cultures of either Mycoplasma conjunctivae (6 calves) or Acholeplasma laidlawii (8 calves). Calves were observed for clinical signs of infectious bovine keratoconjunctivitis (IBK), and eyes were examined for the test organisms by bacteriologic cultural technique for 60 days. Acholeplasma laidlawii became established in the eyes of 5 of 8 calves; M conjunctivae became established in the eyes of 4 of 6 calves. On day 28, eyes of 9 of the 14 calves were exposed by conjunctival instillation to Moraxella bovis, and all developed IBK. Five calves exposed to Moraxenjunctivae or A laidlawii, but not to Mor bovis, did not develop IBK. Four calves not exposed to M conjunctivae or A laidlawii, but exposed to Mor bovis, developed IBK. Mycoplasmas do not have a major role in IBK, but might produce ancillary effects similar to those of infectious bovine rhinotracheitis virus, wind, ultraviolet radiation, dust, and other irritants.

Simple method for immunofluorescent identification of mycoplasma colonies

General purpose rubber stoppers proved to be a simple, rapid, and satisfactory method of transferring mycoplasma colonies from agar to microscope slides for immunofluorescence.

Effectiveness of certain teat dips and sanitizers in vitro and on teat skin against Mycoplasma agalactiae subsp. bovis

Seven teat dip and sanitizer products were tested in vitro and in vivo for mycoplasmacidal activity against Mycoplasma agalactiae subsp. bovis (M. bovimastitidis). Most, but not all products tested appeared to kill the mycoplasma at satisfactory dilutions. These mycoplasma survived longer on teat skin during humid, rainy weather than during warm, dry weather. Acholeplasma laidlawii was frequently found on normal teat skin.

Experimentally produced calf pneumonia

Experimental pneumonia was produced in calves by the endobronchial inoculation of pneumonic lung homogenates. Irradiated homogenates produced minimal pneumonia. Ampicillin treatment of the homogenates and the experimental calves reduced the extent of pneumonia. Treatment with tylosin tartrate prevented experimental pneumonia. These results suggest that the total pneumonia was due to organisms susceptible to tylosin tartrate and that the residual pneumonia remaining after ampicillin treatment was due to organisms susceptible to tylosin tartrate but not to ampicillin. Of the organisms isolated from the lungs, the ones in this latter category most likely to be responsible are Mycoplasma dispar and ureaplasmas (T-mycoplasmas).

Mycoplasmas and cuffing pneumonia in a group of calves

The mycoplasmas found in the lungs of 20 calves, housed together for six months, and the related pulmonary pathology are reported. Twelve calves had cuffing pneumonia and in this group there was a significantly higher isolation frequency of Mycoplasma dispar and Ureaplasma spp compared with the non-pneumonic group. Mycoplasma bovirhinis and Acholeplasma laidlawii were isolated from the lungs of calves in both groups. Mycoplasma arginini was not recovered from the lungs of any calf. The significance of the peribronchiolar lymphocytic accumulation in the lungs of the non-pneumonic animals and their differentiation from peribronchiolar lymphocytic cuffs is discussed.

[Identification of mycoplasmas isolated from monkeys]

The authors identified 15 strains of mycoplasmae isolated from Papio hamadryas suffering from leukemia and from healthy Macacus rhesus, a green monkey and saimiri. A study was made of their biochemical properties, antigenic properties in the reaction of growth depression with immune sera to a number of standard strains, and also the protein composition by electrophoresis in polyacrylamide gel (EPAG). A number of mycoplasmae were identified as A. laidlawii, M. arthritidis--Campo and M. cynomolgus KI, affilated to M. orale II. Four strains were apparently a mixture of three mycoplasmae (M. cynomolgus KI, M. arthritidis--Campo, and M. hyorhinis). Six strains of mycoplasmae (three enzymatically active, belonging according to EPAG data to a single serological type, and three--enzymatically inert, differing by EPAG) could not be identified.