Investigation of the Genetic Basis of Tetracycline
Resistance in Staphylococcus aureus from Pakistan
Farhat Ullah1,
Salman Akbar Malik2, Jawad Ahmed3,
Farman Ullah1, Syed Majid Shah1,
Muhammad Ayaz1, Sajid Hussain1 and
Lubna Khatoon4
1Kohat University of Science
and Technology, Kohat, 2Quaid-i-Azam
University, Islamabad, 3Khyber Medical
University, Peshawar, 4University of
Agriculture, Faisalabad, Pakistan
*For correspondence:
Email:
farhataziz80@hotmail.com Tel:
0092-3339361513, 0092-922-554188
Received: 26 March 2011
Revised
accepted: 13 October 2012
Tropical
Journal of Pharmaceutical Research, December 2012;
11(6):
925-931
http://dx.doi.org/10.4314/tjpr.v11i6.8
Abstract
Purpose: To determine the prevalence and
genetic basis of tetracycline resistance in
Staphylococcus aureus.
Methods: One hundred and thirty (130)
clinical isolates of S. aureus were collected from
Khyber Teaching Hospital, Peshawar, Pakistan.
Susceptibility to antibiotics (doxycycline, tetracycline
and minocycline) was determined by Kirby-Bauer disc
diffusion method with minimum inhibitory concentration
(MIC) evaluated on Muller-Hinton agar as described by
the Clinical and Laboratory Standards Institute (CLSI).
The tetracycline-resistant strains (TET-R) were screened
by polymerase chain reaction (PCR) for the presence of
four common tetracycline resistance determinants, viz,
tet(K), tet(L), tet(M) and tet(O).
Results: Sixty (46.0 %) of these isolates
were methicillin-resistant S. aureus (MRSA) while 70
(54.0 %) were methicillin-susceptible S. aureus (MSSA).
Seventy four (56.9 %) strains were resistant to
tetracycline (TET-R), 30 (23.1 %) to minocycline and 23
(17.7 %) to doxycycline. A majority of the MRSA were
resistant to tetracyclines and all the MSSA were
sensitive to doxycycline and minocycline. The tet(K)
gene was found in 58 isolates and tet(L) in one isolate.
No tet(M) and tet(O) were detected.
Conclusion: This study indicates that resistance
to tetracyclines is mainly by efflux pumps mediated by
tet(K) in S. aureus in northwestern Pakistan.
Keywords: Staphylococcus aureus, Antimicrobial
susceptibility, Antibiotic resistance, Tetracycline,
Pakistan.
