This study examined the prevalence of bovine mastitis and identified the bacterial causes and their antibiotic sensitivity at the Kenya Agricultural and Livestock Research Organization (KARI) research farm in Naivasha, Kenya. The researchers found that subclinical mastitis was more common than clinical mastitis. Staphylococcus species were the most frequently isolated bacteria. Gentamicin and ampicillin showed the highest antibiotic sensitivity, making them the recommended treatments. The study concluded that mastitis rates were relatively high and recommended improved milking hygiene, treatment of clinical cases, and antibiotic sensitivity testing to guide therapy and prevent indiscriminate antibiotic use.

1. PREVALENCE OF BOVINE MASTITIS
AND ITS BACTERIAL CAUSES WITH
THEIR ANTIBIOTIC SENSITIVITY IN A
RESEARCH CENTRE FARM IN KENYA
*Ndirangu, P.N.1
, Siamba, D.2
, Wesonga, H.O.1
, Nyongesa, P2
andMugambi, J.M.1
1
KARI, Veterinary Research Centre, P.O. Box, 32 00902, Kikuyu
2
Masinde Muliro University of science and technology, P.O. Box 190, Kakamega
Presenter: Dr. Peter N. Ndirangu

2. INTRODUCTION
• Dairy industry is largest agricultural sub-sector
in Kenya contributing 14% of agricultural GDP
and 3.5% of total national GDP (GoK, 2008)
• The sector is faced with challenges including
bovine mastitis. Mastitis causes economic
losses; decreased milk production, veterinary
costs, premature culling of cows, cost of
replacement as well as discarding and down-
grading of milk (Mungube et al., 2005)

3. • Mastitis refers to inflammation of mammary
glands, caused by infectious and non-
infectious agents. Main etiological agents are
infectious microorganisms, bacteria
• Occurs in two forms: subclinical and clinical
Mastitic milk Normal milk

4. • Clinical is easily diagnosed via physical
examination of udder and milk.
• Subclinical require use of tests like strip cup,
California mastitis test (CMT), somatic cell
count, culture
Strip cup CMT reagent & paddle

5. Culture and sensitivity testsSomatic cell analyzer for milk

6. • What is the treatment for mastitis?
Antibiotics are largely applied in mastitis
therapy and Some of those used in Kenya are:
penicillin, streptomycin, tetracycline,
getamycin, ampicillin and sulphonamides
(Ndirangu et al., 2013).
Antibiotics resistance is one reason for low
efficacy of antibiotic therapy of mastitis. In
Kenya only a few studies have reported the
antibiotic sensitivity rates of the bacterial
causes of mastitis (Gitau et al. 2011)

7. • Successful mastitis treatment programs
require prior in vitro antibiotic sensitivity
testing so as to avoid indiscriminate use of
antibiotics. Given systemic or imm.
• What were the big questions?

8. 1. What is the extent of mastitis in the farm?
2. Which are the bacterial etiological agents of
the disease and which are the best drugs to
use?
OBJECTIVES
• To determine the mastitis management
practices and prevalence in cattle.
• To determine the bacterial causes of mastitis
and their antibiotic sensitivity rates in the
Sahiwal and dairy herds.

9. MATERIALS AND METHODS
1. Sampling and study herds
Study design was a cross-sectional study carried
out in two herds of KARI-Naivasha.
Sahiwal herd: sahiwal breed, which is a dual-
purpose breed. The herd size was 192
lactating cows where a random sample of 50
cows was selected
Dairy herd: Made up of Friesians & crossbreeds.
Herd size was 92 lactating cows and a
random sample of 50 cows was selected.

10. Sahiwal herd
Dairy herd

11. 2. Determination of mastitis prevalence
Cow details recorded: type of grazing, breed,
stage of lactation, parity, hygiene status, etc.
Clinical mastitis diagnosed by physical
examination of cows; visual observation,
palpation & stripping to see physical changes
in milk before milk sample collection.
Subclinical form was diagnosed by CMT (David
et al., 2005). The CMT results were
interpreted based on gel formation as -ve (no
gel) or +ve (gel) .. scored 1-3

12. 3. Milk sample collection
389 milk samples collected from 100 cows in 2
herds since some cows had lost quarters.
Collected aseptically. Teats were washed with
warm water, dried with disposable gauze
dipped in 70% ethyl alcohol. The first two
squirts of milk were discarded.

13. 4. Bacterial isolation and identification
Samples for were selected based on their
mastitis status, clinical mastitis samples were
selected and those samples with a CMT score
of 2 and 3. In total, 53 samples were selected
(32 from sahiwal and 21 dairy herd).
1 ml of milk was streaked on to blood agar with
5% sheep blood and incubated aerobically at
37o
C. plates were examined at 24 hours and
those with no growth were re-incubated and
examined the following day.

14. • Bacteria were identified microscopically
through Gram-staining, morphology and
arrangement of the stained bacterial cells,
followed by biochemical tests mainly catalase
test (used for differentiating Gram-positive
cocci and rods) and indole test (for
differentiating Gram-negative cocci) as
described by Holt et al. (1993).

15. 5. Antibiotic sensitivity testing
Sensitivity was determined for 19 bacterial
isolates (15 Staph. species & 4 Strep. Species)
via Kirb-Bauer disc diffusion method (Quinn et
al. ,2000). Isolates selected were those giving
a pure culture and a growth score of 3 or 4.
8Antibiotics used: ampicillin, tetracycline, co-
trimoxazole, streptomycin, kanamycin,
gentamycin, sulphamethoxazole &
chloramphenicol. Zones of inhibition were
measured.

16. RESULTS AND DISCUSSIONS
Managemen
t practices
Grazing
system
Milking
method
Milking
hygiene
Sahiwal herd Free Hand Poor
Dairy herd Semi-zero Machine Good
Prevalence Clinical
mastitis
Subclinical
mastitis
Teat injuries
Sahiwal 3/50 (6%) 27/50(54%) 9/50(18%)
Dairy 0 18/50(36%) 3/50 (6%)

17. • Subclinical mastitis was the most common as
reported by others in different parts of Kenya
(Ngatia, 1988; Omore et al., 1996; Ondieki et
al., 2013). Form of mastitis is an indication of
the degrees of udder infection. The 6% clinical
mastitis in sahiwal cows is similar to 5.6%
prevalence of chronic clinical mastitis
reported by Ondieki et al. (2013). However,
this was less than the 13.3% reported by
Omore et al. (1996) for cows from Kiambu.

18. Prevalence of subclinical mastitis reported here
is similar to those reported by others like
Ngatia, 1988; shem et al., 2001
Prevalence of subclinical mastitis in sahiwal
cows examined was highest during mid-
lactation (4-9 months) of 51.9% and dairy herd
was most prevalent in late lactation (66.7%).
This finding agrees with the observation made
by Ayano et al. (2013).

19. Bacterial isolates
Sahiwal herd: isolation rate was 30/32(93.8%) .
The isolates were Staph. spp 26/30 (86.7%),
Strep. spp. 2/30 (6.3%), Corynebacterium 1/30
(3.3%) and E.coli 1/30 (3.3%).
Dairy herd: isolation rate was 18/21 (85.7%).
Bacteria were Staph. spp 10/18 (55.6%), Strep.
spp. 7/18 (38.9%) and Corynebacterium 1/18
(5.6%).
Similar bacteria have been reported by others
like Gitau et al., 2012; Ondiek, et al., 2013

20. Antibiotic sensitivity
Gentamycin and ampicillin showed highest
sensitivity of 18/19(94.7%), kanamycin (79%),
co-trimoxazole and chloramphenicol (73.7%),
tetracycline (63.2%), streptomycin (52.6%) &
sulphamethoxazole (21.1%). Similar findings
have been reported by others (Ondiek et al.,
2013; Gitau et al., 2011). This may be due to
extensive use and misuse of tetracycline,
streptomycin and penicillin for many years in
Kenya while

21. • Gentamycin & kanamycin were introduced
recently in Kenya thus resistance to the two
drugs has not developed extensively.
CONCLUSIONS AND RECOMMENDATIONS
1. Bovine mastitis in KARI-Naivasha was
relatively high, particularly the subclinical
form, thus effective control measures needs
to be instituted. Such to include;
improvement of milking hygiene, teat
disinfection, routine testing for mastitis,
effective treatment of mastitis cases, among
others.

22. 2. Mastitis etiological agents found were Staph.
spp., Strept. spp., Corynebacterium and E. coli.
Maintenance of environmental hygiene can
help to reduce Intrammamary infections with
Staphylococci and E. coli.
3. Bacteria isolates were most sensitive to
Gentamycin, ampicilin and kanamycin and
therefore these are the drugs of choice for
mastitis therapy in the study area. However,
antibiotic sensitivity testing is a pre-liquisite
prior to initiating mastitis therapy.

23. • Director KARI
• This study was funded by Eastern Africa
Agricultural Productivity Project (EAAPP).
• Authors are grateful to technical staff of KARI-
VRC and MUUST for their part in sample
collection and bacteriological analysis.
• Management and staff of KARI-Naivasha for
allowing us to use their cows.
ACKNOWLEDGEMENTS

24. THANK YOU