This study reports for the first time molecular detection of Anaplasma platys infection in 4 (13.3%) of 30 Malaysian dogs investigated. A low occurrence (3.3%) of Babesia gibsoni was also noted, being detected in one of the 30 dogs. Rickettsia, Bartonella, Orientia tsutsugamushi, and Ehrlichia DNA were not detected in the dog blood samples. The role of A. platys as an agent of canine anaplasmosis and its transmission through Rhipicephalus sanguineus ticks merits further investigation.
A study was undertaken to evaluate the relevance of detecting IgM and IgG antibodies in diagnosis of canine leptospirosis in Kerala, a southern state of India, which is endemic for the disease. A total of 205 blood (35 from healthy vaccinated, 30 from healthy unvaccinated and 140 from diseased dogs) and 151 urine samples (11 from healthy vaccinated and 140 from diseased dogs) were collected from three districts of Kerala, Thrissur, Palakkad and Kozhikode with high incidence of leptospirosis. Recombinant LipL41 protein was used as antigen and IgG and IgM based ELISAs were standardized. The results were compared with the gold standard test, microscopic agglutination test (MAT). The MAT positive samples (146 samples) were divided into those having titre >1:800 and those between 1:100 and 1:400 in view that the former constituted the acute cases. It was found that IgM ELISA was more specific and sensitive in detecting acute cases (MAT >1:800) whereas IgG ELISA was less specific. In case of seroprevalence studies (MAT titre 1:100 to 1: 400), IgG ELISA was found to be more sensitive and specific than IgM ELISA. Receiver operating characteristic curves when plotted, revealed the accuracy of IgM ELISA in acute leptospirosis. Many samples were positive for both IgG and IgM antibodies. Polymerase Chain Reaction (PCR) targeting lipl41 gene was standardized and urine and blood samples from the same dogs were tested. PCR was found to be the specific test for the early detection of leptospires in blood even before seroconversion. However, PCR analysis of the urine samples was found to be insensitive. Hence, it can be concluded that the diagnostic strategies should be modified, and a combination of serological and molecular tests is recommended in endemic areas rather than simple detection of IgM or IgG antibodies, for the early detection of acute clinical cases of leptospirosis.
Otitis externa (OE) is a frequently reported disorder in dogs associated with secondary infections by Staphylococcus, Pseudomonas and yeast pathogens. The presence of biofilms may play an important role in the resistance of otic pathogens to antimicrobial agents. Biofilm production of twenty Staphylococcus pseudintermedius and twenty Pseudomonas aeruginosa canine otic isolates was determined quantitatively using a microtiter plate assay, and each isolate was classified as a strong, moderate, weak or nonbiofilm producer. Minimum biofilm eradication concentration (MBEC) of two ionophores (narasin and monensin) and three adjuvants (N-acetylcysteine (NAC), Tris-EDTA and disodium EDTA) were investigated spectrophotometrically (OD570nm ) and quantitatively (CFU/ml) against selected Staphylococcus and Pseudomonas biofilm cultures. Concurrently, minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) of planktonic cultures were assessed. 16/20 of the S. pseudintermedius clinical isolates were weak biofilm producers. 19/20 P. aeruginosa clinical isolates produced biofilms and were distributed almost equally as weak, moderate and strong biofilm producers. While significant antibiofilm activity was observed, no MBEC was achieved with narasin or monensin. The MBEC for NAC ranged from 5,000-10,000 µg/ml and from 20,000-80,000 µg/ml against S. pseudintermedius and P. aeruginosa, respectively. Tris-EDTA eradicated P. aeruginosa biofilms at concentrations ranging from 6,000/1,900 to 12,000/3,800 µg/ml. The MBEC was up to 16-fold and eightfold higher than the MIC/MBC of NAC and Tris-EDTA, respectively. Disodium EDTA reduced biofilm growth of both strains at concentrations of 470 µg/ml and higher. It can be concluded that biofilm production is common in pathogens associated with canine OE. NAC and Tris-EDTA are effective antibiofilm agents in vitro that could be considered for the treatment of biofilm-associated OE in dogs.
An epidemiological study of Ehrlichia canis infection in dogs in Peninsular Malaysia was carried out using molecular detection techniques. A total of 500 canine blood samples were collected from veterinary clinics and dog shelters. Molecular screening by polymerase chain reaction (PCR) was performed using genus-specific primers followed by PCR using E. canis species-specific primers. Ten out of 500 dogs were positive for E. canis. A phylogenetic analysis of the E. canis Malaysia strain showed that it was grouped tightly with other E. canis strains from different geographic regions. The present study revealed for the first time, the presence of genetically confirmed E. canis with a prevalence rate of 2.0% in naturally infected dogs in Malaysia.
Fleas of the genus Ctenocephalides serve as vectors for a number of rickettsial zoonoses, including Rickettsia felis. There are currently no published reports of the presence and distribution of R. felis in India, however, the ubiquitous distribution of its vector Ctenocephalides felis, makes it possible that the pathogen is endemic to the region. This study investigates the occurrence of Rickettsia spp. infection in various subspecies of C. felis infesting dogs from urban areas of Mumbai, Delhi and Rajasthan in India.
Ehrlichia canis is among the most prevalent tick-borne pathogens infecting dogs worldwide, being primarily vectored by brown dog ticks, Rhipicephalus sanguineus sensu lato (s.l.). The genetic variability of E. canis has been assessed by analysis of different genes (e.g., disulfide bond formation protein gene, glycoprotein 19, tandem repeat protein 36 - TRP36) in the Americas, Africa, Asia, and in a single dog sample from Europe (i.e., Spain). This study was aimed to assess the variations in the TRP36 gene of E. canis detected in naturally infected canids and R. sanguineus s.l. ticks from different countries in Asia and Europe. DNA samples from dogs (n = 644), foxes (n = 146), and R. sanguineus s.l. ticks (n = 658) from Austria, Italy, Iran, Pakistan, India, Indonesia, Malaysia, the Philippines, Singapore, Thailand, Vietnam, and Taiwan were included in this study. Ehrlichia canis 16S rRNA positive samples (n = 115 from the previous studies; n = 14 from Austria in this study) were selected for molecular examination by analyses of TRP36 gene. Out of 129 E. canis 16S rRNA positive samples from dogs (n = 88), foxes (n = 7), and R. sanguineus s.l. ticks (n = 34), the TRP36 gene was successfully amplified from 52. The phylogenetic analysis of the TRP36 pre-repeat, tandem repeat, and post repeat regions showed that most samples were genetically close to the United States genogroup, whereas two samples from Austria and one from Pakistan clustered within the Taiwan genogroup. TRP36 sequences from all samples presented a high conserved nucleotide sequence in the tandem repeat region (from 6 to 20 copies), encoding for nine amino acids (i.e., TEDSVSAPA). Our results confirm the US genogroup as the most frequent group in dogs and ticks tested herein, whereas the Taiwan genogroup was present in a lower frequency. Besides, this study described for the first time the US genogroup in red foxes, thus revealing that these canids share identical strains with domestic dogs and R. sanguineus s.l. ticks.