ABSTRACT
Staphylococcus aureus is gaining worldwide attention because of its substantial impact on public health. The current study aimed to characterize S. aureus strains isolated from wild birds in the Kasur district of Punjab, Pakistan from 2021 to 2022. A total of one hundred samples were collected from five wild bird species. The samples were enriched, inoculated on selective agars and cultured for 24 hr at 37.00 ËC. All isolates were verified by matrix-assisted laser desorption ionization-time-of-flight mass spectrometry (MALDI-TOF MS) and polymerase chain reaction (PCR) after Gram staining. Positive isolates were screened for phenotypic (Kirby-Bauer disk diffusion and minimum inhibitory concentration s), genotypic antibiotic resistance, and virulence genes. These samples yielded 30 (30.00%) S. aureus isolates, confirmed by polymerase chain reaction utilizing the 16S rRNA gene. Staphylococcus aureus was more prevalent in cloacal samples (16.00%) than oral samples (14.00%). Various S. aureus isolates showed varying degrees of resistance to three different antibiotics. Oxacillin (56.66%; n = 17) and tetracycline (33.33%; n = 10) showed the highest resistance rates with the lowest susceptibility (43.33%; n = 13). In contrast, vancomycin, rifampicin, linezolid, and daptomycin were 100% susceptible. Further disc diffusion study revealed resistance to tetracycline (33.33%), erythromycin (16.66%), and gentamicin (10.00%). The tetK gene was found in 33.33% of wild bird samples, while the ermA gene was found in 16.66% of samples. The aacA-D gene was only found in three (10.00%) isolates. None of the isolates tested positive for virulence genes. In conclusion, S. aureus is carried by wild birds in this area, posing a potentail threat to both humans and animals.
ABSTRACT
Hypervirulent Aeromonas hydrophila (vAh) has emerged as the etiologic agent of epidemic outbreaks of motile Aeromonas septicemia (MAS) in high-density aquaculture of farmed carp in China and catfish in the United States, which has caused millions of tons of lost fish. We conducted a global survey to better understand the evolution, geographical distribution, and phylogeny of vAh. Aeromonas isolates were isolated from fish that showed clinical symptoms of MAS, and pure cultures were screened for the ability to utilize myo-inositol as the sole carbon source. A total of 113 myo-inositol-utilizing bacterial strains were included in this study, including additional strains obtained from previously published culture collections. Based on a gyrB phylogeny, this collection included 66 A. hydrophila isolates, 48 of which were vAh. This collection also included five new vAh isolates from diseased Pangas catfish (Pangasius pangasius) and striped catfish (Pangasianodon hypophthalmus) obtained in Cambodia and Vietnam, respectively. Genome sequences were generated from representative vAh and non-vAh isolates to evaluate the potential for lateral genetic transfer of the myo-inositol catabolism pathway. Phylogenetic analyses of each of the nine genes required for myo-inositol utilization revealed the close affiliation of vAh strains regardless of geographic origin and suggested lateral genetic transfer of this catabolic pathway from an Enterobacter species. Prediction of virulence factors was conducted to determine differences between vAh and non-vAh strains in terms of virulence and secretion systems. Core genome phylogenetic analyses on vAh isolates and Aeromonas spp. disease isolates (55 in total) were conducted to evaluate the evolutionary relationships among vAh and other Aeromonas sp. isolates, which supported the clonal nature of vAh isolates. IMPORTANCE This global survey of vAh brought together scientists that study fish disease to evaluate the evolution, geographical distribution, phylogeny, and hosts of vAh and other Aeromonas sp. isolates. In addition to vAh isolates from China and the United States, four new vAh isolates were isolated from the lower Mekong River basin in Cambodia and Vietnam, indicating the significant threat of vAh to modern aquaculture and the need for improved biosecurity to prevent vAh spread.
ABSTRACT
Brucellosis is an important zoonotic disease of animals and humans caused by bacteria of the genus Brucella. Brucellae are Gram-negative intracellular bacteria which infect a wide variety of animals including goats, sheep, buffaloes, cows, pigs, and wildlife. The objectives of this study were to determine the seroprevalence and spatial distribution of brucellosis in Central Punjab, Pakistan. A total of 1083 blood samples of goats, sheep, buffaloes, and cows were collected from 38 villages of four districts (Kasur, Faisalabad, Lahore, and Okara) of Punjab, Pakistan, and screened for brucellosis by Rose Bengal Plate test (RBPT) and PCR confirmed. Epidemiological, demographic data and GPS coordinates for every sample were collected. By using interpolation of the Aeronautical Reconnaissance Coverage Geographic Information System (Arc GIS), a surface plot was generated applying inverse distance weight (IDW). It was found that 35 (3.23%) serum samples were positive for brucellosis. In eight (61.5%), six (75%), seven (87.5%), and eight (89%) villages, positive goats, sheep, buffaloes, and cattle were detected, respectively. In general, older animals are more often positive for brucellosis. In goats bucks were more often RBPT positive than females while in sheep, buffaloes, and cattle more females were positive. The spatial distribution of brucellosis shows that it is widely distributed in the western region of the study area in goats and in the South-West region in sheep. Similarly, for buffaloes it is restricted to the south-east and north-west regions, and in cattle brucellosis is present in western region of study area only. Reflected by this study, brucellosis poses a risk for livestock in developing countries due to lack of awareness by officials, owners, and consumers, and control measures are missing. A risk map of brucellosis was generated to develop effective strategies for awareness rising and to improve the quality of control programs in Pakistan.