Prevalence of some mastitis causes in dromedary camels in Abu Dhabi , United Arab Emirates

The present study was designed to determine the prevalence of different types of mastitis in camels in U.A.E. and to identify the causative microorganisms and their sensitivity to different antimicrobial agents. From 162 lactating she-camels, 630 milk samples were collected from different cities in Abu Dhabi Emirate/UAE. The overall prevalence of mastitis was 18.52% (7.94% on quarter basis), the prevalence of clinical and sub clinical mastitis was found to be 24.70% and 11.67% on animal basis, respectively; it being 9.70% and 5.86% on quarter basis, respectively. The hind quarters were more frequently affected than the fore quarters. Bacteriological examination of milk samples revealed that Staphylococcus was the chief etiological agents both in clinical and sub clinical mastitis (41.67%) in camels, followed by Streptococcus spp. (21.67%), Enterobacter spp. (15.00%), C. pyogenes (10.00%), Micrococcus spp. (5.00%), Pasteurells spp. (5.00%) and Pseudomonas aeruginosa (1.66%). Most of the Staphylococcus spp., Streptococcus spp. and C. pyogenes strains were sensitive to carbenicillin, gentamycin, kanamycin, and erythromycin, but resistant to colistin and sulphamethoxazole. Other pathogens like Enterobacter, Micrococcus, Pasteurella spp. and Ps. aeuroginosa isolates showed variable sensitivities to the antimicrobials.


Introduction
The dromedary camel (Camelus dromedarius) is the most important livestock animal in the desert and semidesert areas of Northern and Eastern Africa as well as in the deserts of the Arabian Peninsula.Dromedary camels rearing in the UAE are mainly for milk, meat production and for racing purposes (1).In UAE, the population of dromedary camels is around 459,242 (2).All are onehumped camels and are commonly found in certain parts of UAE, especially Abu Dhabi and Al-Ain cities and Western region.Peak milk yield of 20-40 liter per day has been recorded (3)(4)(5).Mastitis is a complex disease occurring world-wide among dairy animals, with heavy economic losses (6)(7)(8)(9) due to of reduced milk yield, degradation of milk quality and additional cost in the care and treatment of mastitis (10).Bacterial infections are considered the primary cause of mastitis in domestic animals (10).Reports of inflammation of the camel udder have appeared from various countries, such as Egypt (11,12), India (13), Saudi Arabia (14,15), Somalia (16,17), Sudan (18), UAE (19).Few available literatures indicate that Staphylococcus aureus, Streptococcus spp.(10,14,(20)(21)(22)(23)(24)(25), Micrococcus spp.(12,20,26), Streptococcus agalactiae (19,27,28), coagulase negative staphylococci (20), Pasteurella haemolytica (21), Escherichia coli (20,21) and Corynebacterium spp.(14,24) have been implicated as causes of mastitis in camels.Accordingly, the present study was taken up with a view to determine the prevalence of different types of mastitis in camels in U.A.E., to identify the causative microorganisms and to determining the sensitivity of mastitis pathogens to different antimicrobial agents.Accordingly, the present study was taken up with a view to determine the prevalence of different types of mastitis in camels in U.A.E., to identify the causative microorganisms and to determining the sensitivity of mastitis pathogens to different antimicrobial agents.

Materials and methods
For assessing the prevalence of different types of clinical mastitis in camels, a systemic survey was conducted; this was done by visiting different camel herds around Abu Dhabi Emirate in the time period between September 2009 to December 2011.The camels were allowed to graze freely in the desert, but were also supplemented with concentrate feed and green grass.The information pertaining to the camels examined during this study was conducted.This included age, lactation number, stage of lactation, pregnancy, previous mastitis history, etc.
Clinical mastitis was recognized by abnormal milk secretion, signs of udder inflammation and detection of mastitis pathogens by bacteriological culture, whereas subclinical mastitis was recognized by apparently normal milk, total count of somatic cells and the presence of pathogenic microorganisms.

Collection of milk samples
A total of 630 milk samples from 162 lactating shecamels, were collected from the individual quarters infected with different types of subclinical and clinical mastitis separately in the sterilized test tubes under aseptic precautions, in accordance with International Dairy Federation standards (29).The milk samples immediately after collection were taken to the central laboratory at Al Wathba Veterinary Hospital, Baniyas, Abu Dhabi for bacteriological examinations.

Cultural isolation
Using standard microbiology techniques including: Culture on general, selective and special indicators media with the special supplement and different atmospheres necessary for different bacteria.Whether they are fast or slow growing and fastidious or regular in their growth needs (aerobic, 10% Co2 and anaerobic conditions), (30).Primary incubation may take from 24-72 hrs according to the microorganism species.Temperature of incubation is 37 °C for most of cases although some cases need to be incubated on another range (25 -45°C) (31,32).Identification using commercially available sets of biochemical and enzymatic testing for the identification of the isolates (API 20 A, NE, E and API 20 Coryn) and rapid microbial detection systems like Vitek 2 (Biomerioux France).

Antimicrobial sensitivity test
The antimicrobial sensitivity test was conducted using Bauer-Kirby technique, as described by (33).The antimicrobial agents used in this study were carbenicillin, gentamycin, kanamycin, erythromycin, ampicillin, cephalothin, tetracycline, penicillin G, colistin, sulphomethoxazole and streptomycin.

Statistical Analysis
The SPSS 20 software was used for all statistical analyses.Differences were considered significant at a level of P<0.05.

Prevalence of mastitis
In order to determine the prevalence of subclinical and clinical mastitis in camels, a total of 162 lactating shecamels (630 quarters) were examined for the presence of mastitis.The results are presented in Table 1.Out of 85 camels (340 quarters) examined for the presence of clinical mastitis, 21 camels (33 quarters) were found to have clinical mastitis, the incidence being 24.70% (9.70% on quarter basis).A total of 77 camels were examined for estimating the prevalence of subclinical mastitis, 30 (11.67%) camels were found to have subclinical mastitis; these animals were carrying mastitis pathogens in their udder secretion.Subclinical infection of mastitis was detected in 17 (5.86%) of the 290 quarters examined.Taking into consideration all the 162 camels examined during this study, the prevalence of mastitis on animal basis was found to be 18.52%, while on quarter basis 7.94%.It was further observed that hind quarters were affected with clinical and subclinical infections (69.69% and 76.47%, respectively) more frequently than fore quarters (30.30% and 23.53 %, respectively) (Table 2).

Frequency distribution of mastitis pathogens
The data available on the relative frequency of different types of microorganisms encountered in udder infection (Table 3) revealed that Staphylococcus was the most important organism involved in the causation of clinical and subclinical mastitis in camels (41.67 %).Streptococcus spp.came next in importance (21.67%), followed by Enterobacterium spp.(15.00%), C. pyogenes (10.00%), while the prevalence of miscellaneous organisms was low.Among the staphylococcal infections, S.aureus was the predominant in the infections of clinical and subclinical mastitis (38.33%).while among the streptococcal infection, Str.agalactiae was predominant (13.33 %).

Sensitivity of mastitis pathogens
As many as 60 isolates obtained from the cases of clinical and subclinical mastitis, during the present study, were subjected to sensitivity test, using 11 different antimicrobial agents as listed in Table 4.It is evident from the table that most of the Staphylococcus spp., Streptococcus spp.and C. pyogenes strains (> 80%) were sensitive to carbenicillin, gentamycin, kanamycin and erythromycin.All these isolates were however found resist to colistin and sulphamethoxazole.The Enterobacter isolates showed moderate sensitive to carbenicillin and sulphamethoxazole, while less sensitive or even resist to the other antimicrobial agents.All the Micrococcus isolates were found highly sensitive to carbenicillin, gentamycin, cephalothin and sulphamethoxazole.While the Pasteurella spp.showed highly sensitive only to carbenicillin and cephalothin.Ps. aeruginosa were found resist to all antimicrobial agents except for carbenicillin.

Discussion
The prevalence of camel mastitis as revealed during the present study is considered low, especially when compared to the report of (10,19,21,25,(34)(35)(36)(37), which revealed the prevalence rate ranging from 38%-83%.There is no definite explanation for the relative low prevalence of mastitis in camels in this study, but the possible factors contributing to it may be the hygienic milking procedures followed by the camel owners and the good hygienic condition of the milking area.It was also noticed during the present study that the prevalence of clinical mastitis was higher than subclinical infections.However, (12)(13)(14)19,21,36,(38)(39)(40)(41) who found subclinical mastitis seems to be more common.The majority of the clinical cases in this study were sub acute infections, with signs of swelling of the udder and teats, heat, congestion and pain of the mammary gland as well as abnormal milk secretion.However, (42) who reported chronic mastitis (57.15%) was the commonest clinical mastitis.Peracute, chronic and gangrenous mastitis have been described in camels (13,14,18,21,25,(41)(42)(43).It was further observed that hind quarters were affected with clinical and subclinical infections more frequently than fore quarters.A higher risk of infections in hind quarters compared to the front ones which could be due to the unfavorable hygienic condition; greater exposure to dung and urine.In addition, due to the shorter length of the hind teats with a corresponding shorter teat canal, the defence potential in the hind quarter could be decreased.However, (26) found that subclinical mastitis was higher in fore quarters than hind quarters.Bacteriological examination of milk samples revealed that Staphylococci was the chief etiological agents both in clinical and sub clinical mastitis (41.67%) in camels, followed by Streptococcus spp.(21.67%),Enterobacter spp.(15.00%), and C. pyogenes (10.00%), while the incidence of miscellaneous organisms was low.These findings, in general, agree with those of other workers investigating in camels in Iraq (21,42), in Saudi Arabia (14,25,43,45), in Egypt (21,34,39) in U.A.E.(19,46,47), in Sudan (18), In India (13,36), in Nigeria (48), and in Kingdom of Bahrain (50).However, (10) from Ethiopia found the predominant etiological agents of camel mastitis in the study area were found to be coagulase negative staphylococci.(24) reported that the most predominant bacterial isolates were Micrococcus spp., Staphylococcus aureus, Streptococcus spp.and Corynebacterium spp.The isolation of genera of pathogenic bacteria from the camel milk samples suggests the need for strict hygienic measures during the production and handling of camel milk to reduce public health hazards.Education of the camel owners about the importance of hygienic milking practices would minimize the adverse effect of mastitis on the yield and quality of camel milk.A study to determine the sensitivity of mastitis pathogens, isolated during the present investigations, revealed that Most of the Staphylococcus spp., Streptococcus spp.and C. pyogenes strains were sensitive to carbenicillin, gentamycin, kanamycin, and erythromycin, but resistant to colistin and sulphamethoxazole.The other mastitis pathogens like Enterobacter, Micrococcus, Pasteurella spp.and Ps.aeruginosa isolates were showed variable pattern of sensitivity to the antimicrobial agents.This suggested that these antimicrobial agents could be used for treatment of mastitis in camels in U.A.E.More or less similar pattern of sensitivity of the bacterial isolates in the present study to some of the above mentioned antimicrobial agents have been reported by (24,26,44,48,50).

Table 1 :
Incidence of clinical and subclinical mastitis in camels.

Table 2 :
Distribution of clinical and subclinical infections in camels according to the position of quarters involved.

Table 3 :
Relative frequency of different type of mastitis pathogens in clinical and sub clinical infections.

Table 4 :
In vitro sensitivity of mastitis pathogens isolates.