- Bell Raj Eapen
MD, DNB, MSc (bioinf)
- Murali Srinivasan
- Geetanjali Bhas MD, DNB
Dr. Bell Raj Eapen
Atlas Star Medical Centre
P.B.No: 112392, Dubai, UAE
Background and Objectives:
Antimicrobial resistance is on the rise and its
early detection is important in implementing effective
Materials and Methods: This
is a retrospective study of the antibiotic sensitivity
profile of 107 culture positive samples collected
over a period of 17 months. The antimicrobial
susceptibility tests were done using the Bauer
- Kirby method.
Results: E-coli was the commonest
organism isolated. Penicillin G and Ciprofloxacin
were the most effective antibiotics against gram
+ve and gram -ve infections respectively.
Discussion: Antibiotics like
Co-trimoxazole and Gentamycin fared better than
newer antibiotics because of limited use.
Key Words: Antibiotic Sensitivity,
Over the past decade, antimicrobial resistance
has emerged in all kinds of micro-organisms worldwide
and Dubai is no exception. This is primarily due to
the increase in antibiotic abuse.1 Early detection of
emerging trends in antimicrobial resistance may facilitate
implementation of effective control measures.
Dubai has a large expatriate population. Since it is
the economic hub of the region, a large number of people
travel in and out of Dubai. This may facilitate the
importation of various micro-organisms to the region.
The laboratory testing of antibiotic susceptibility
contributes directly to patient care and the expertise
of the microbiology laboratory can have powerful influence
on antibiotic usage. We present the data collected over
a period of 17 months in a private clinic in Dubai,
mainly catering to the expatriate Indian population.
This is a retrospective study of the antibiotic
sensitivity profile of 107 positive culture samples
collected over a period of 17 months starting from January
2004. The samples which included pus from various lesions,
urine, stool, throat swab and vaginal swabs were carefully
collected without contamination from external sources
according to NCCLS guidelines.2 The culture media used
in our study were nutrient agar, blood agar (incubated
anaerobically if necessary), chocolate agar, CLED agar
(for urine) and Mc Conkey's agar.
Bacterial growth was identified based
on the colony characteristics, Gram's stain and biochemical
reactions.3 Antimicrobial susceptibility tests were
done by the Bauer - Kirby method using Mueller - Hinton
agar.4 The diameter of the zone of inhibition in millimeters
was scored as per Table 1.
Mean Sensitivity Score was calculated
as per the following formula.
Mean Sensitivity Score = (Total Sensitivity score /
No. Of samples analyzed) x 100
We collected data from 107 positive culture
samples belonging to 74 male and 33 female patients.
The age distribution is as per Figure 1. Urine and throat
swabs showed maximum positivity with 37 and 28 each.
The number of various samples showing positive culture
is depicted in Figure 2. E-coli was the commonest organism
grown in urine and stool while streptococcus pyogenes
was predominantly seen in throat swabs. The complete
list of all the organisms isolated is shown in Table
2. The Total sensitivity score of each organism against
commonly used antibiotics is given in Table 3. E-coli
showed maximum sensitivity to ciprofloxacin (Mean score
= 85) while streptoccus aeureus and streptococcus pyogenes
showed maximum response to penicillin G (Mean score
= 100). The Mean sensitivity score of commonly used
antibiotics is shown in Figures 3 and 4.
E.Coli was the predominant organism isolated
in Urine and stool samples. However ear, nose and throat
samples showed mainly gram +ve organisms like Staph.
Aureus and Streptococcus pyogenes. Klebsiella was the
commonest Gram -ve organism isolated from these samples.
Gram +ve organisms showed maximum sensitivity
to Penicillin G and Erythromycin while Ciprofloxacin
was most effective against Gram -ve organisms. Co-trimoxazole
showed a broad spectrum of activity and it performed
better than Amoxycillin with Clavulanic acid. Among
the parenteral antibiotics Gentamycin fared better than
most third generation Cephalosporins.
Co-Trimoxazole and Gentamycin are rarely
used these days because of the allergic reactions5 and
ototoxicity6 respectively. Hence these old antibiotics
are still effective in most infections. However the
widely used newer antibiotics are slowly becoming less
effective in this region.
There are reports of even Methicillin
Resistant Staph Aureus responding to Co trimoxazole.7
However the use of Co-Trimoxazole as a prophylactic
antibiotic in HIV infected patients may change its sensitivity
profile in the future.8 The objectives of an antibiotic
strategy are to implement clinical guidelines which
cover the treatment of an individual patient and the
policies based on these which will have maximum effects
in public health.9
||Del Rosso JQ. Antibiotic resistance:
overview and significance in dermatology. Cutis
2005; 75: 12-8.
||Zapantis A, Lacy MK, Horvat RT et
al. Nationwide Antibiogram Analysis Using NCCLS
M39-A Guidelines. J Clin Microbiol 2005; 43: 2629-34.
|| Gobernado M, Lopez-Hontangas JL.
[Bacterial identification methods]. Enferm Infecc
Microbiol Clin 2003; 21 Suppl 2: 54-60.
||Matsen JM, Koepcke MJ, Quie PG. Evaluation
of the Bauer-Kirby-Sherris-Turck single-disc diffusion
method of antibiotic susceptibility testing. Antimicrobial
Agents Chemother 1969; 9: 445-53.
||Mohamed KB. Fixed drug eruption associated
with co-trimoxazole. J Pediatr 1999; 135: 396.
||Khosla SN, Nand N, Khosla P et al.
Gentamycin ototoxicity. J Assoc Physicians India
1988; 36: 182.
||Bishara J, Pitlik S, Samra Z et al.
Staphylococcus aureus, Israel, 1988-1997. Emerg
Infect Dis 2003; 9: 1168-9.
||Crewe-Brown HH, Reyneke MP, Khoosal
M et al. Increase in trimethoprim-sulphamethoxazole
(co-trimoxazole) resistance at Chris Hani Baragwanath
Hospital, Soweto, in the AIDS era. S Afr Med J 2004;
||Brooks A. UK strategy to cut antibiotic
use outlined. Bmj 1998; 317: 699.