Investigation of Mannheimia haemolytica bacteriophages relative to host diversity

Pollution by Antibiotics and Antimicrobial Resistance in LiveStock and Poultry Manure in China, and Countermeasures

The demand for animal protein has increased considerably worldwide, especially in China, where large numbers of livestock and poultry are produced. Antibiotics have been widely applied to promote growth and prevent diseases. However, the overuse of antibiotics in animal feed has caused serious environmental and health risks, especially the wide spread of antimicrobial resistance (AMR), which seriously affects animal and human health, food safety, ecosystems, and the sustainable future development of animal protein production. Unfortunately, AMR has already become a worldwide challenge, so international cooperation is becoming more important for combatting it. China’s efforts and determination to restrict antibiotic usage through law enforcement and effective management are of significance. In this review, we address the pollution problems of antibiotics; in particular, the AMR in water, soil, and plants caused by livestock and poultry manure in China. The negative impact of widespread and intensive use of antibiotics in livestock production is discussed. To reduce and mitigate AMR problems, we emphasize in this review the development of antibiotic substitutes for the era of antibiotic prohibition.

Diversity and characterization of temperate bacteriophages induced in Pasteurella multocida from different host species

Background

Bacteriophages play important roles in the evolution of bacteria and in the emergence of new pathogenic strains by mediating the horizontal transfer of virulence genes. Pasteurella multocida is responsible for different disease syndromes in a wide range of domesticated animal species. However, very little is known about the influence of bacteriophages on disease pathogenesis in this species.

Results

Temperate bacteriophage diversity was assessed in 47 P. multocida isolates of avian (9), bovine (8), ovine (10) and porcine (20) origin. Induction of phage particles with mitomycin C identified a diverse range of morphological types representing both Siphoviridae and Myoviridae family-types in 29 isolates. Phage of both morphological types were identified in three isolates indicating that a single bacterial host may harbour multiple prophages. DNA was isolated from bacteriophages recovered from 18 P. multocida isolates and its characterization by restriction endonuclease (RE) analysis identified 10 different RE types. Phage of identical RE types were identified in certain closely-related strains but phage having different RE types were present in other closely-related isolates suggesting possible recent acquisition. The host range of the induced phage particles was explored using plaque assay but only 11 (38%) phage lysates produced signs of infection in a panel of indicator strains comprising all 47 isolates. Notably, the majority (9/11) of phage lysates which caused infection originated from two groups of phylogenetically unrelated ovine and porcine strains that uniquely possessed the toxA gene.

Conclusions

Pasteurella multocida possesses a wide range of Siphoviridae- and Myoviridae-type bacteriophages which likely play key roles in the evolution and virulence of this pathogen.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12866-021-02155-9.

Feeding subtherapeutic antimicrobials to low-risk cattle does not confer consistent performance benefits

Stanford, K., Gibb, D. J., Schwartzkopf-Genswein, K. S., Van Herk, F. and McAllister, T. A. 2015. Feeding subtherapeutic antimicrobials to low-risk cattle does not confer consistent performance benefits. Can. J. Anim. Sci. 95: 589–597. Two-hundred and forty steers were obtained from the same ranch in each of 2 yr. Growth performance, health status and carcass characteristics from steers fed subtherapeutic antimicrobials were compared with those of control steers without antimicrobial metaphylaxis. Experimental groups included Control, not fed antimicrobials; CTCS-700, fed 350 mg head−1 d−1 chlortetracycline (CTC) and 350 mg head−1 d−1 sulfamethazine; CTC-11, fed 11 mg kg−1 CTC; TYL, fed 11 mg kg−1 tylosin phosphate; and CTC-350, fed 350 mg head−1 d−1 CTC. Steers were housed in pens of 10 steers and fed antimicrobials during both backgrounding and finishing periods. The incidence of bovine respiratory disease, pinkeye and bloat did not differ among experimental groups, although the incidence of foot rot was lower in Control steers (P<0.05) than in steers receiving TYL. In both years of the study, overall performance (backgrounding+finishing) was not improved by subtherapeutic antimicrobials. Similarly, carcass characteristics and the incidence and severity of liver abscesses were not improved compared with Control steers by feeding subtherapeutic antimicrobials. The results of the present study demonstrate that low-risk steers may be managed in small pens with equivalent growth performance, carcass characteristics and health status to steers fed subtherapeutic antimicrobials.

Isolation and Characterization of Lytic Properties of Bacteriophages Specific for M. haemolytica Strains

Aim of Study

The objective of this study was isolation and morphological characterization of temperate bacteriophages obtained from M. haemolytica strains and evaluation of their lytic properties in vitro against M. haemolytica isolated from the respiratory tract of calves.

Material and Methods

The material for the study consisted of the reference strain M. haemolytica serotype 1 (ATCC^®) BAA-410™, reference serotypes A1, A2, A5, A6, A7, A9 and A11, and wild-type isolates of M. haemolytica. Bacteriophages were induced from an overnight bacterial starter culture of all examined M. haemolytica strains treated with mitomycin C. The lytic properties and host ranges were determined by plaque assays. The morphology of the bacteriophages was examined in negative-stained smears with 5% uranyl acetate solution using a transmission electron microscope. The genetic analysis of the bacteriophages was followed by restriction analysis of bacteriophage DNA. This was followed by analysis of genetic material by polymerase chain reaction (PCR).

Results

Eight bacteriophages were obtained, like typical of the families Myoviridae, Siphoviridae and Podoviridae. Most of the bacteriophages exhibited lytic properties against the M. haemolytica strains. Restriction analysis revealed similarities to the P2-like phage obtained from the strain M. haemolytica BAA-410. The most similar profiles were observed in the case of bacteriophages φA1 and φA5. All of the bacteriophages obtained were characterized by the presence of additional fragments in the restriction profiles with respect to the P2-like reference phage. In the analysis of PCR products for the P2-like reference phage phi-MhaA1-PHL101 (DQ426904) and the phages of the M. haemolytica serotypes, a 734-bp phage PCR product was obtained. The primers were programmed in Primer-Blast software using the structure of the sequence DQ426904 of reference phage PHL101.

Conclusions

The results obtained indicate the need for further research aimed at isolating and characterizing bacteriophages, including sequence analysis of selected fragments. Moreover, standardization of methods for obtaining them in order to eliminate M. haemolytica bacteria involved in the etiopathogenesis of BRDC is essential.

Comparative analysis of multiple inducible phages from Mannheimia haemolytica

BACKGROUND

Mannheimia haemolytica is a commensal bacterium that resides in the upper respiratory tract of cattle that can play a role in bovine respiratory disease. Prophages are common in the M. haemolytica genome and contribute significantly to host diversity. The objective of this research was to undertake comparative genomic analysis of phages induced from strains of M. haemolytica serotype A1 (535A and 2256A), A2 (587A and 1127A) and A6 (1152A and 3927A).

RESULTS

Overall, four P2-like (535AP1, 587AP1, 1127AP1 and 2256AP1; genomes: 34.9-35.7 kb; G+C content: 41.5-42.1 %; genes: 51-53 coding sequences, CDSs), four λ-like (535AP2, 587AP2, 1152AP2 and 3927AP1; genomes: 48.6-52.1 kb; 41.1-41.4 % mol G+C; genes: 77-83 CDSs and 2 tRNAs) and one Mu-like (3927AP2; genome: 33.8 kb; 43.1 % mol G+C; encoding 50 CDSs) phages were identified. All P2-like phages are collinear with the temperate phage φMhaA1-PHL101 with 535AP1, 2256AP1 and 1152AP1 being most closely related, followed by 587AP1 and 1127AP1. Lambdoid phages are not collinear with any other known λ-type phages, with 587AP2 being distinct from 535AP2, 3927AP1 and 1152AP2. All λ-like phages contain genes encoding a toxin-antitoxin (TA) system and cell-associated haemolysin XhlA. The Mu-like phage induced from 3927A is closely related to the phage remnant φMhaMu2 from M. haemolytica PHL21, with similar Mu-like phages existing in the genomes of M. haemolytica 535A and 587A.

CONCLUSIONS

This is among the first reports of both λ- and Mu-type phages being induced from M. haemolytica. Compared to phages induced from commensal strains of M. haemolytica serotype A2, those induced from the more virulent A1 and A6 serotypes are more closely related. Moreover, when P2-, λ- and Mu-like phages co-existed in the M. haemolytica genome, only P2- and λ-like phages were detected upon induction, suggesting that Mu-type phages may be more resistant to induction. Toxin-antitoxin gene cassettes in λ-like phages may contribute to their genomic persistence or the establishment of persister subpopulations of M. haemolytica. Further work is required to determine if the cell-associated haemolysin XhlA encoded by λ-like phages contributes to the pathogenicity and ecological fitness of M. haemolytica.