Prevalence and Antimicrobial Susceptibility of Bovine Mycoplasma Species in Egypt

Simple Summary

Bovine Mycoplasma species, particularly antimicrobial resistant Mycoplasma bovis are important causes of bovine respiratory disease (BRD) in cattle, which causes major economic losses worldwide. Thus, the current study aimed to determine the prevalence and antimicrobial resistance profiles of bovine Mycoplasma spp. isolated from cattle’s respiratory tracts, in addition to evaluating the fluoroquinolone resistance in the recovered isolates using broth microdilution and conventional PCR techniques in Egypt. Our result showed that M. bovis was the most common spp. (61%), followed by M. bovirhinis (15%). In total, mycoplasma isolates were more prevalent among all examined lung tissues (38%), followed by nasal swabs (35%), tracheal tissues (28%), and tracheal swabs (27%). All the examined mycoplasma isolates (n = 76) were 100% susceptible to spectinomycin, tulathromycin, spiramycin, and tylosin, but high doxycycline and enrofloxacin minimum inhibitory concentrations (MICs) values were observed among 43.4% and 60.5% of the tested isolates, respectively. Three and two mycoplasma isolates with high enrofloxacin MICs were confirmed to be M. bovis and M. bovirhinis, respectively, by PCR assays. All molecularly confirmed mycoplasma isolates (n = 5) were positive for the gyrA gene (100%), meanwhile, three isolates (60%) were positive for the parC gene. In conclusion, understanding antimicrobial resistance mechanisms is a significant tool for the future development of genetic-based diagnostic techniques for the rapid detection of resistant mycoplasma strains.

Abstract

Among many bovine Mycoplasma species (spp.), Mycoplasma bovis is recognized as a significant causative agent of respiratory diseases in cattle. In recent years, resistant M. bovis isolates, especially to fluoroquinolones, have been reported globally as a result of the extensive usage of antimicrobials in the treatment of bovine pneumonia. Therefore, the aim of this study is to investigate the prevalence and antimicrobial susceptibility patterns of bovine Mycoplasma spp. isolated from the respiratory tracts of cattle in Egypt and to assess the fluoroquinolones resistance in the recovered mycoplasma isolates via broth microdilution and conventional PCR techniques. Conventional phenotypic methods identified 128 mycoplasma isolates (32%) from 400 different samples, with M. bovis being the predominant spp. (61%), followed by M. bovirhinis (15%). Of note, mycoplasma isolates were rarely isolated from total healthy lung tissues (7/55, 12.7%), but they were frequently isolated from pneumonic lungs (31/45, 68.9%). All the examined mycoplasma isolates (n = 76) were sensitive to tilmicosin, tylosin, tulathromycin, spiramycin, and spectinomycin (100% each), while 60.5% and 43.4% of the examined isolates had high minimum inhibitory concentration (MIC) values to enrofloxacin and doxycycline, respectively. Three and two mycoplasma isolates with high enrofloxacin MICs were confirmed to be M. bovis and M. bovirhinis, respectively, by PCR assays. All molecularly confirmed mycoplasma isolates (n = 5) were positive for the gyrA gene (100%); meanwhile, three isolates (60%) were positive for the parC gene. In conclusion, our findings revealed alarming resistance to enrofloxacin and doxycycline antibiotics; thus, antimicrobial usage must be restricted and molecular techniques can help in the rapid detection of the resistant strains.

Cytotoxic essential oil from Annona sengalensis Pers. leaves

The cytotoxicity against brine shrimp of the essential oil obtained from the leaves of Annona senegalensis Pers. (Annonaceae) was studied. The confirmation of this toxicity has been done by using selected tumor cell lines (A549, HT29, MCF 7, RPMI, and U251). The results showed that the total oil and its fractions have showed mild to moderate cytotoxicity in brine shrimp lethality bioassay with LC50 = 27.3 μg/ml, and against some human tumor cell lines. The total oil and its fractions were analyzed by gas chromatography/mass spectroscopy (GC/MS). Seventy three compounds were identified.

Apoptosis and lens vesicle development

PURPOSE

To study the development of the rat lens vesicle in relation to apoptosis.

MATERIALS AND METHODS

Fetuses of Wistar Kyoto rats were removed by laparotomy on day 10-15 of gestation. Some fetuses were fixed in 2% paraformaldehyde and embedded in paraffin for a TUNEL technique examination of DNA fragmentation. Macrophages were stained immunohistochemically with antibody. Some fetuses were fixed in 4% glutaraldehyde and 1% osmic acid and embedded in Luveak 812, then examined with a transmission electron microscope (TEM).

RESULTS

On day 11 of gestation (E11) before the start of lens invagination, apoptotic changes were noted in the cells between the surface ectoderm and optic vesicle, with the appearance of phagocytic cells. Apoptotic cells were present at the junction of the surface ectoderm and the lens placode, in the ventral and dorsal thirds of the lens placode and in the outer layer of the optic vesicle in the same axes on E12. Apoptotic changes appeared in the lens stalk, surface ectoderm and the anterior lens epithelium on E12.5. The lens vesicle was detached completely from the surface ectoderm by E13 and some cells had the typical characteristics of macrophages in the extracellular space between the surface ectoderm and the anterior lens epithelium. Apoptotic changes were confirmed by the TUNEL method, and macrophages were stained immunohistochemically.

CONCLUSIONS

Apoptosis may have a major role during the whole process of lens vesicle development. Apoptosis may eliminate the cells between the surface ectoderm and the optic vesicle, help trigger invagination and facilitate separation from the ectoderm. Apoptosis might aid in the bowing of the optic vesicle during lens invagination.