A cross sectional study to assess nasal carriage of methicillin resistant Staphylococcus aureus in healthcare professionals in a tertiary care ...
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205
RESEARCH ARTICLE
A cross sectional study to assess nasal carriage of methicillin resistant
Staphylococcus aureus in healthcare professionals in a tertiary care hospital
Fibhaa Syed, Nasim Akhtar, Mohammad Ali Arif, Adil Ramzan Ramzan, Rauf Niazi, Syed ubaid Hasnain, Muhammad Danish Hanif,
Sana Asghar, Aamna Naheed
Abstract
Objective: To determine the nasal carriage of staphylococcus aureus and methicillin-resistant staphylococcus
aureus among healthcare workers in a tertiary care setting.
Methods: The cross-sectional study was conducted at the Pakistan Institute of Medical Sciences, Islamabad,
Pakistan, from April to July 2018, and comprised healthcare workers at the institution. Nasal swabs were collected
and cultured on Mannitol salt agar. Mannitol fermenting colonies which were gram-positive cocci, catalase-positive
and coagulase-positive were identified as staphylococcus aureus. Antibiotic susceptibility test was performed by
modified Kirby-Bauer disc diffusion method. Methicillin resistance was detected using cefoxitin disc diffusion
method. Data was analysed using SPSS 23.
Results: Of the 210 nasal swabs, 52(24.76%) had a staphylococcus aureus growth, and of them, 15(7.1%) were
methicillin-resistant. No association could be established with either any single category of healthcare worker or an
inter-department variation (p>0.05). Likewise, there was no association with age, gender, duration of service,
smoking, co-morbidities, use of antibiotics in the preceding six months, treating a patient with methicillin-resistant
staphylococcus aureus in the preceding six months and hospitalisation in the preceding year (p>0.05).
Conclusion: The frequency of nasal carriage of methicillin resistant staphylococcus aureus amongst healthcare
workers was regardless of the nature of their professional engagement.
Keywords: Methicillin resistant staphylococcus aureus, Nasal carriage, Healthcare professionals. (JPMA 71: 205; 2021)
DOI: https://doi.org/10.47391/JPMA.062
Introduction a higher treatment cost but also higher mortality.5
Staphylococcus (S.) aureus and coagulase-negative The anterior nares are the main reservoir of MRSA,
staphylococci are both commensal and opportunistic although other body sites are also colonised, such as skin,
pathogens that colonise humans.1 Although hands, axillae and intestinal tract.1,6 Three types of MRSA
asymptomatic carriage of these microorganisms is carriers have been described: non-carriers, persistent
common but they also contribute significantly to hospital carriers and intermittent carriers. Persistent carriers are
associated infections (HAIs).2 Methicillin-sensitive chronically colonised by the same strain. Intermittent
staphylococcus aureus (MSSA) and methicillin-resistant carriers are colonised with varying strains for short
staphylococcus aureus (MRSA) have been responsible for periods of time. A form of short-term carriage is transient
endemic and epidemic nosocomial infections. MRSA is carriage which is identified during or after a work shift and
undoubtedly the most common antimicrobial resistant in most cases lost before the next shift.7 Nasal carriage of
pathogen worldwide and poses a threat in the hospital S. aureus has been associated with an increased risk of
and the community.3 infection for the colonised individual, but the risk to
S. aureus can cause a multitude of infections, including, persistent carriers is unclear.8 Approximately 5% of the
but not limited to, the skin, soft tissues, bones, joints, colonised healthcare workers develop clinical infections.7
indwelling catheters and prosthetic devices infections, Healthcare workers (HCWs) are likely to play an
infective endocarditis, pneumonia, bacteraemia, important role as vectors through transmission of MRSA
septicaemia and shock.4 MRSA is associated with poorer rather than being the main sources.7 The issue for
clinical outcomes compared to MSSA infections. With screening HCWs for colonisation with resistant bacteria
limited treatment options, MRSA infections not only have has been broached, but the topic remains controversial
and open to further discussion based on evidence.9,10
Department of General Medicine, Pakistan Institute of Medical Sciences, The nasal carriage of MRSA varies widely amongst
Islamabad, Pakistan. HCWs and data from Pakistan is limited, especially from
Correspondence: Fibhaa Syed. Email: fibhaasyed@gmail.com the federal capital territory. Additionally, factors that
Vol. 71, No. 1-B, January 2021F. Syed, N. Akhtar, M. A. Arif, et al
206
could influence the nasal carriage of MRSA, including preceding year. A sterile cotton swab with sterile test
duration of employment, smoking status, co- tube was used for sample collection. The swabs were
morbidities, use of antibiotics, treating patients with moistened with sterile normal saline and carefully
MRSA etc., have not been previously assessed in inserted into each nostril. The sample was collected by
Pakistan. rotating the swab five to six times in both nares. The
samples were immediately transported to the
The current study was planned to fill the gap by laboratory for further processing.
identifying the frequency of MRSA in the anterior nares
of HCWs working in a tertiary care setting. It also The samples were inoculated onto Nutrient agar and
planned to identify any risk factors for nasal carriage of Mannitol salt agar within one hour of collection, and
staphylococci based on personal and professional incubated at 37°C for 18-24 hours. Mannitol fermenting,
parameters. yellow-coloured colonies were subjected to gram
staining. Further biochemical tests, like catalase and
Subjects and Methods deoxyribonuclease (DNase), were performed for the
The cross-sectional study was conducted at the confirmation of staphylococcus. In accordance with the
Pakistan Institute of Medical Sciences (PIMS), Clinical Laboratory Standards Institute (CLSI) guidelines,
Islamabad, Pakistan, from April to July 2018. After resistance to methicillin was determined by disk diffusion
approval from the institutional ethics review method using 30μg Cefoxitin disk (Oxoid, UK) on Mueller
committee, the sample size was calculated by taking Hinton agar plates. For each strain, a bacterial suspension
MRSA prevalence 8.5 % in HCWs11 using Rao online adjusted to 0.5 McFarland turbidity standards was used.
calculator at 95% confidence level and standard error The plates were incubated for 24 hours at 37°C. The
5%.12 HCWs from all categories and departments of the results were interpreted according to CLSI criteria. A zone
hospital were included, while all individuals suffering of 22mm was
from a nasal pathology, rhinitis or upper respiratory considered sensitive. MRSA ATCC 33591 was used as
tract infection were excluded. resistant control while MSSA ATCC 25923 was taken as
Those included after taking informed consent were sensitive control.13
categorised as doctor, nurse, paramedic staff Data was analysed using SPSS 23. Continuous variables
(technician, operation theatre assistant, anaesthesia were reported as means ± standard deviation (SD), and
assistant, physiotherapist and dispenser), office worker categorical variables were reported as frequencies and
(clerk, peon, computer operator and receptionist) and percentage. Chi-square test was applied to find
janitorial staff. HCW profile was recorded, such as age, association of different variables between those positive
gender, ward where they worked, working category and for MRSA and those negative for it. After checking for data
duration of service in the healthcare sector. Additional normality, t-test was applied for comparison of mean
information, such as smoking status, the presence of co- values related to age and duration of service with nasal
morbidities, such as diabetes mellitus (DM), carriage of MRSA. P207 A cross sectional study to assess nasal carriage of methicillin resistant Staphylococcus aureus...
Table-2: Methicillin-resistant staphylococcus aureus (MRSA) nasal carriage amongst none in the MRSA group and 1(0.51%) in the non-MRSA
healthcare workers from different departments. group had treated a patient with MRSA in the preceding
six months (p>0.05).
Department MRSA Total
Positive Negative In the MSSA group, 23(62.1%) were males compared to
83(47.97%) in the non-MSSA group. The mean age in
General Medicine 1 33 34
MSSA was 36.11±10.23 years compared to 38.07±10.52
Pulmonology Nil 4 6
Gastroenterology 3 18 21
years in on-MSSA (p>0.05). The mean duration of service
General Surgery 3 25 28 11.05±10.64 years in MSSA compared to 12.83±10.63
Orthopaedics 1 7 8 years in non-MSSA subjects (p>0.05).
Neurosurgery Nil 4 4
Neurology 1 8 9 In the MSSA group, 15(40.54%) were smokers; 9(24.3%)
Psychiatry Nil 3 3 had co-morbidities; none (0%) had been hospitalised
Urology Nil 5 5 over the preceding year; and 25(67.57%) had received
Ear, Nose, Throat (ENT) Nil 6 6 antibiotics in the preceding six months. The
Emergency 1 18 19 corresponding numbers in the non-MSSA group were
Nephrology Nil 8 8 57(32.95%); 28(15.7%); 1(0.56%); and 99(72.26%). None
Oncology Nil 3 3 of the differences were was statistically significant
Cardiology Nil 7 7
(p>0.05).
Plastic surgery Nil 3 3
Ophthalmology 1 4 5 Discussion
Paediatrics Nil 7 7
Gynaecology& Obstetrics 3 20 23
Nosocomial infections are a major problem for infection
Dermatology Nil 4 4 control worldwide. MRSA has been recognised as one of
Radiology 1 6 7 the most sinister pathogens responsible for such
Total 15 195 210 infections.14
The present study was designed keeping in mind the
37(17.6%) were MSSA and 15(7.1%) were MRSA. threat of cross-transmission of MRSA through nasal
carriage in HCWs. One of the most effective methods of
From among MRSA samples, 8(53.3%) were from males. In reducing nosocomial infections by this organism may be
the 195(92.9%) individuals who tested negative for MRSA, by identifying the carriers and eradicating it. MRSA
98(50.2%) were males (p>0.05). The mean age of the healthy carriers are asymptomatic, but they transmit the
individuals who tested positive for MRSA was 39.07±11.26 pathogen to others.15
years, while the mean age of individuals who tested
negative was 37.62±10.435 years (p>0.05). The highest As elsewhere, MRSA epidemiology varies in different
prevalence of MRSA nasal carriage was amongst doctors parts of Pakistan. The current study reported that out
(Table-1). of 210 HCWs evaluated, 52(24.76%) were positive for
staphylococcus; 37(17.6%) MSSA and 15(7.1%) MRSA. A
Of the 15 MRSA cases, 3(20%) each were found in study in Rawalpindi showed 18.2% HCWs were nasal
Gastroenterology, General Surgery, and Gynaecology carriers of S. aureus and 1.5% (7/468) were nasal
departments (Table-2). carriers of MRSA.16 In Lahore General Hospital, 380
The mean duration of employment in the MRSA group samples were studied, and 89(23.42%) yielded growth
was 13.67±12.28 years, and in the non-MRSA group it of S. aureus, with overall MRSA frequency of 8.15%.17 A
was 12.43±10.526 years (p>0.05); 7(46.7%) in MRSA and study in Allama Iqbal Medical College, Lahore,
64(32.9%) in non-MRSA groups were smokers (p>0.05); evaluated 100 nasal swabs; 40% were S. aureus and
in MRSA group, 1(9.1%) had DM, 3(12%) had HTN and 27% were MRSA.18
none had IHD, while in the non-MRSA groups the In a study in Peshawar, MRSA prevalence in HCWs was
corresponding numbers were 10(5.13%), 22(11.28%) 62.7% compared was to 37.22% in the community.19
and 1(0.51%) (p>0.05); in the MRSA group, there was
none with a history of hospitalisation within the A study which was limited to the orthopaedic staff of a
preceding years, while there was 1(0.51%) in the non- hospital in Peshawar reported 1.4% MRSA-positive
MRSA group (p>0.05); 11(73.3%) in the MRSA group and cases.20 A few studies have found inter-department
112(57.43%) in the non-MRSA group had received variation in MRSA prevalence,16,17 while the current study
antibiotics in the preceding six months (p>0.05), and could not establish such a variation. Some studies also
Vol. 71, No. 1-B, January 2021F. Syed, N. Akhtar, M. A. Arif, et al
208
reported a relationship between HCW category and MRSA Source of Funding: None.
status.16-18 The current study found the highest
prevalence amongst doctors but the difference was not References
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