Nirmal A Pathare1, Sara Tejani1, Harshini Asogan1, Gaitha Al Mahruqi1, Salma Al Fakhri1, Roshna Zafarulla1 and Anil V. Pathare2*
1Oman Medical College and 2Sultan Qaboos University Hospital, Muscat, Oman
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Background: The prevalence of community-associated methicillin-resistant Staphylococcus aureus [CA-MRSA] is unknown in Oman.
Methods: Nasal and cell phones swabs were collected from hospital visitors and health-care workers on sterile polyester swabs and directly inoculated onto a mannitol salt agar containing oxacillin, allowing growth of methicillin-resistant microorganisms. Antibiotic susceptibility tests were performed using Kirby Bauer’s disc diffusion method on the isolates. Minimum inhibitory concentration (MIC) was determined for vancomycin and teicoplanin against the resistant isolates of MRSA by the Epsilometer [E] test. A brief survey questionnaire was requested be filled to ascertain the exposure to known risk factors for CA-MRSA carriage.
Results: Overall, nasal colonization with CA-MRSA was seen in 34 individuals (18%, 95% confidence interval [CI] =12.5%-23.5%), whereas, CA-MRSA was additionally isolated from the cell phone surface in 12 participants (6.3%, 95% CI =5.6%-6.98%). Nasal colonization prevalence with hospital-acquired [HA] MRSA was seen in 16 individuals (13.8%, 95% confidence interval [CI] =7.5%-20.06%), whereas, HA-MRSA was additionally isolated from the cell phone surface in 3 participants (2.6%, 95% CI =1.7-4.54). Antibiotic sensitivity was 100% to linezolid and rifampicin in the CA-MRSA isolates. Antibiotic resistance to vancomycin and clindamycin varied between 9-11% in the CA-MRSA isolates. Mean MIC for vancomycin amongst CA- and HA-MRSA were 6.3 and 9.3 μg/ml, whereas for teicoplanin they were 13 and 14 μg/ml respectively by the E-test. There was no statistically significant correlation between CA-MRSA nasal carriage and the risk factors (P>0.05, Chi-square test).
Conclusions: The prevalence of CA-MRSA in the healthy community hospital visitors was 18 % (95% CI, 12.5% to 23.5%) as compared to 13.8% HA-MRSA in the hospital health-care staff. Despite a significant prevalence of CA-MRSA, these strains were mostly sensitive. Recommendation: The universal techniques of hand washing, personal hygiene and sanitation are thus warranted.
Methicillin resistant Staphylococcus aureus [MRSA] has emerged as a
virulent pathogen and is a leading cause of nosocomial infections.[1-3]
Although first reported in 1972, there are increasing number of
hospital outbreaks with increased mortality, morbidity and health care
costs. Furthermore, since 1990s, MRSA has also emerged as cause of infection in the community.[5,6]
Community-acquired MRSA [CA-MRSA] is usually seen in subjects with well
recognized risk factors such as intravenous drug usage, debilitating
co-morbid conditions like diabetes mellitus, malignancies,
cardiovascular or renal failure, etc.[7-11] However, the first reported CA-MRSA was in Australian aboriginals and native Canadians in the 1990s.
The first reported cases of CA-MRSA in the USA were seen with no
contact to health care system in native Americans from Minnesota, North
Dakota and Nebraska as well as in Los Angeles and San Francisco.[13,14]
The emergence of CA-MRSA in the community is a significant public health concern as transmission from individual to individual is a primary health care concern leading to the spread of microorganisms of significant potential for morbidity and mortality. However, not the mere presence of CA-MRSA but its antibiotic sensitivity-resistance pattern plays a significant role in the risk assessment. Methicillin-resistant strains became more common than methicillin-susceptible strains, first in hospitals [HA-MRSA] and later in the community.[3,15] Prevalence of CA-MRSA is variable, being low in some European countries, whereas, there is increasing evidence that it is significantly higher in many other parts of the world.[16,17] Some studies from India have reported a prevalence of CA-MRSA in the range of 4.6–10.6% from a rural setting,[18,19] whereas others like Gaud et al reported CA-MRSA prevalence of 16.4% in an urban setting from Bangalore, in India.
Thus, in view of the rising trend of the increasing prevalence of CA-MRSA, and its propensity to develop resistance, it is imperative not only to study the prevalence of CA-MRSA in Oman, but also its antibiotic susceptibility and resistance pattern. Unfortunately, the prevalence of CA-MRSA in Oman is unknown.
Aim of this study
Patients and Methods
The hospital visitor community comprised of 189 subjects, with a mean age of 25.43±17.5 years old; most of the subjects were female (63.5%). The hospital health- care workers comprised of 116 subjects, with a mean age of 33.23±8.9 years old; the majority of the persons in this cohort were females (67.2%) (Table 1a). There was no statistically significant correlation between CA- and HA- MRSA isolates and the demographic characteristics or the risk factors namely gender, underlying co-morbidities like diabetes, hypertension, skin/soft tissue infections, skin ulcers/wounds, recent exposure to antibiotics, or hospital exposure (Table 1b; P>0.05, Chi-square test).
|Table 1a. Demographic characteristics for the two study cohorts.|
|Table 1b. Underlying risk factors for the two cohorts of the study|
Overall, in the hospital visitor community, CA-MRSA were isolated in 34 individuals from their nasal vestibules giving a carriage rate of 18.0% (95% CI=12.5% to 23.5%). (Table 2) CA-MRSA was also isolated from the cell phone surfaces in 12 individuals yielding a carriage rate of 6.3% (95% CI=5.6% to 6.98%). In 2 participants (1.06%), CA-MRSA was isolated both from nasal vestibules and from their cell phone swabs. In the hospital health workers, the nasal carriage [HA-MRSA] was observed in 16 individuals with a colonization rate of 13.8% (95% CI=7.5% to 20.06%) and in 3 individuals, cell phone swabs grew HA-MRSA giving a colonization rate of 2.6% (95% CI=1.7% to 4.54%). However, none of the hospital health workers showed positive MRSA isolation from nose and cell-phone from the same individual.
|Table 2. Prevalence of CA-MRSA and HA-MRSA isolates in the Community and Health Care staff .|
A total of 46 and 19 isolates were respectively obtained and
confirmed as CA-MRSA and HA-MRSA from the culture characteristics and
Gram staining in the community hospital visitors and the hospital
health-care workers. Amongst the CA-MRSA isolates antibiotic resistance
with erythromycin and clindamycin varied between 11-35%, whereas, most
isolates were sensitive to rifampicin, doxycycline, vancomycin,
linezolid, and teicoplanin. (Figure 1a)
However, amongst the HA-MRSA isolates, a significantly higher antibiotic resistance was seen with both erythromycin and clindamycin, varying between 42-63%, whereas, the sensitivity of HA-MRSA isolates to rifampicin, doxycycline, vancomycin, and linezolid was 95%, 89%, 84%, and 100% respectively (Figure 1b). Overall, there was no significant differences in the resistance pattern between the nasal and cell phone CA-MRSA isolates [Table 3; p>0.05, Chi-square test] Overall, the vancomycin-resistant CA-MRSA were 2.1%. Mean MIC by the E test for vancomycin amongst CA-MRSA isolates [n=4] was 6.5 μg/ml with a range between 6 to 8, whereas, amongst the HA-MRSA isolates [n=3] it was 9.3 μg/ml with a range between 8 to 12. Mean MIC by the E test for teicoplanin amongst CA-MRSA isolates [n=4] was 13 μg/ml with a range between 12 to 16, whereas amongst the HA-MRSA isolates [n=4] it was 14 μg/ml with a range between 12 to 16.
|Figure 1a. Antibiotic resistance and susceptibility pattern by the Kirby-Bauer Disc diffusion method in CA-MRSA isolated (n=46).|
|Figure 1b. Antibiotic resistance and susceptibility pattern by the Kirby-Bauer Disc diffusion method in HA-MRSA isolated (n=19).|
|Table 3. Antibiotic sensitivity and resistance pattern of the CA-MRSA [n=19] and HA-MRSA isolates [n=46].|
The authors wish to thank Dean, Oman Medical College for providing necessary research facilities. This work was supported by a FURAP grant in August 2013 from the ‘The Research Council’ [TRC] of the Sultanate of Oman. (Grant No. FRP/OMC/13/001).