Research Article

Nasal Carriage of MRSA among Healthy College Students and Livestock

Kenneth Nnamdi Anueyiagu*, James Jingmang Kopmut, Chrysantus Achi Lagi and Kelly Nkem Okoh

Federal College of Animal Health and Production Technology, NVRI Vom

Editor | Muhammad Abubakar, National Veterinary Laboratories, Park Road, Islamabad, Pakistan.

Received | October 18, 2019; Accepted | February 14, 2020; Published | March 17, 2020

*Correspondence | K.N. Anueyiagu, Federal College of Animal Health and Production Technology, NVRI Vom; Email: anueyiagunnamdi@yahoo.com

Citation | Anueyiagu, K.N., J.J. Kopmut, C.A. Lagi and K.N. Okoh. 2020. nasal carriage of MRSA among healthy college students and livestock. Veterinary Sciences: Research and Reviews, 6(1): 33-39.

DOI | http://dx.doi.org/10.17582/journal.vsrr/2020/6.1.33.39

Keywords | Nasal carriage, Staphylococcus aureus, MRSA, methicillin, livestock, students

Introduction

S. aureus is one of the most significant bacterium associated with the nasal cavity of man and animals causing different pathogenic infection on the skin and soft tissues of both man and animals (Khalid and Ali, 2015).

Duration of treatment depends on the site and severity of the infection. Antibiotic resistance strains of S. aureus was first discovered in the year 1880 at Aberdeen, Scotland by surgeon Sir Alexander Ogston in pus from surgical abscesses in a knee joint.

Resistance of S. aureus to methicillin, a typical beta-lactam agent, was first reported in 1961. The ability of S. aureus to be resistance to methicilin is due to its acquisition of the mecA gene, that encodes for a new protein designated PBP2a, belonging to a family of enzymes necessary in building the bacterial cell wall. PBP2a has a very low affinity for beta-lactam antibiotics and confers resistance to methicillin and other beta-lactams (Pantosti, 2007)

Hiffinan in 2015 reported that MRSA strains are the cause of many zoonotic infections in the world today. A population of about 94,360 invasive MRSA infections is diagnosed annually in the US, with 18,650 associated deaths; with approximately 86% of all the invasive MRSA infection are health care associated nosocomial infections.

MRSA infection has been established in literature to affect livestock and are otherwise referred to as Livestock associated-Methicillin Resistant Staphylococcus aureus (LA-MRSA). The first documented account of MRSA in livestock was in a bovine mastitis case in the 1970s. Afterwards, MRSA had been isolated from food animals such as cattle, pigs, horses, and poultry (Aires-de-Sousa, 2017). While Wulf et al. (2006) screened 80 veterinary students and 99 veterinarians for MRSA, Voss et al. (2005) indicated transfer of MRSA from pigs to caretakers.

Using the economic models and findings of Lee et al. (2013), a single community associated with MRSA cost third party payers about $2,277 - $3,200 (which is about N455,400 – N640,000), and society $7,070 - $20,489 (about N1,414,000 –N14,097,800). Depending on the age of the patient, MRSA is peculiar and represent a substantial burden of resistant infections in hospitals (Dilip, 2003).

Direct contact with MRSA positive animals has been reported to be a major risk factor for humans (Grøntvedt et al., 2016) and if not managed properly could lead to outbreaks especially in underdeveloped countries where biosecurity in livestock farms is at the minimal.

The objective of this study was to establish the rate of nasal carriage of MRSA among students in a college of animal health and production, and livestock in the college farm.

Materials and Methods

Study area

This study was designed to cross-sectional survey the nasal carriage of MRSA among students and livestock in an animal health and production college. Approval was obtained from institutional committee on sampling ethics. Samples were collected between October 2017 and April 2018.

Sample collection

A total of about 160 nasal samples were collected from college students and livestock. Ten samples were collected from 13 classes of both National Diploma (ND) and Higher National Diploma (HND) streams from 3 schools (Science and Technology, Animal Health and Production Technology, Agriculture Technology and Environment Science) making a total of 130 samples. While 10 samples each were collected from goats, sheep and cattle respectively. One sterile swab stick, moistened in sterile distilled saline was inserted into the inner nasal septum of anterior nares of students and livestock, rubbed several times according to Hema et al. (2017). Then removed, capped, labeled and transported immediately in Amie’s transport media to Microbiology laboratory of Federal College of Animal Health and Production Technology Vom, for analysis.

Bacteriological assay

About 4.5 ml of peptone water was dispensed in 160 empty samples bottles each into which the 160 samples collected were placed for enrichment in peptone water and then incubated for 24 hours at 37 oC. Thereafter, a loopful was inoculated onto Mannitol Salt Agar (MSA) plates and incubated for another 24 hours at 37 oC. Suspected S. aureus colonies with yellowish appearance were observed and recorded. Other biochemical tests were carried out according to Cheesebrough (2000).

Susceptibility testing of MRSA isolates

Antibiotic sensitivity test was carried out with organism subculture onto Mueller Hinton Agar, oxacillin test disc placed on it and incubated again for 24 hours at 37 oC.

The diameter of zone of inhibition produced by each of the discs was measured, recorded, and isolates that were ≤ 10 mm were classified as resistant, 11-12 mm as intermediates, and ≥ 13 mm as susceptible based on standard interpretative chart as recommended by the clinical and laboratory start instate (CLSI, 2014).

Data analysis

Chi-Square test of independence, and correlation coefficient were performed to test for the association between the prevalence of MRSA in students and livestock sampled using R commander (Fox, 2019) software.

Results

Among the livestock sampled, sheep had the highest prevalence of 80% of S. aureus isolated; among students sampled, 68% those of Animal health and Production Technology had S. aureus being the highest group (Table 1). Out of 160 samples collected and analyzed from students and livestock, 83 (51.9%) S. aureus were isolated while 80 (44.44%) MRSA were identified.

Table 2 illustrates the association between the prevalence of MRSA in gender of animals and students. All the species had odds ratio of 1 signifying that the prevalence of MRSA has equal likelihood of occurrence. S. aureus isolates from students were more susceptible to antibiotics than isolates of livestock (Table 3). From the susceptibility pattern, the S. aureus isolates of students showed more resistance gentamycin than other antibiotics used (Table 4). While Table 5 showed the response of S. aureus isolates from sheep to antibiotics according to the susceptibility, intermediate and resistance values of each antibiotics.

Table 1: Prevalence of S. aureus based on livestock and students.

Specie	Sample (n)	Positive (n)	Prevalence %
Livestock
Cattle	10	4	40
Sheep	10	8	80
Goat	10	5	50
Students
Science and technology	60	27	45.0
Animal health and production technology	50	34	68.0
Agricultural technology and env. science	20	5	25.0
Total	160	83	51.9

 

Table 2: Gender prevalence of MRSA isolated from livestock and students.

Animal	Gender	Sample (n)	Positive (%)	P-value	OR (95% C1)
Cattle	Bull Cows	2 1	20 10	1.000	1 1(0.046, 64.797)
Sheep	Ram Ewes	2 5	20 50	1.000	1 1(0.088, 6.748)
Goat	Buck Does	2 3	20 30	1.000	1 1(0.077, 9.567)
Students	Male Female	26 39	20 30	1.000	1 1(0.441, 2.277)

 

Table 3: Antibiotics susceptibility of S. aureus from student and ruminant.

Animal	Sample (n)	Positive (n)	Prevalence %
Cattle	4	0	0
Sheep	8	1	12.5
Goat	5	0	0
Students	66	16	24.24

 

Discussions

The study shows 50.8% overall prevalence of nasal colonization of S. aureus in healthy students in the College of Animal Health and Production Technology with a prevalence of 45%, 68%, and 25% from students of schools of Science and Technology, Animal Health and Production, and Agricultural Technology and Environmental Science respectively. These results showed the students’ nasal passage were considerably colonized by this organism. This is consistent with Gulani et al. (2016) with an overall prevalence of 44.3%. The School of Animal Health and Production Technology had the highest level of S. aureus prevalence compared to the two other schools. This could be as a result of their regular contact the livestock and environment during farm and clinical practical classes. Zomer et al. (2017) reported a comparatively low prevalence of 0.56% for people who do not have professional contact with livestock which is similar to low prevalence of students of Agricultural Technology and Environmental Science respectively.

Table 4: Prevalence of antibiotics resistance among students.

Antibiotics	Susceptible (%)	Intermediate (%)	Resistance (%)
Rifampicin	38 (18.63)	4 (8.16)	8 (7.34)
Gentamycin	16 (7.84)	N/A	34 (31.19)
Erythromycin	21 (10.29)	7 (14.29)	22 (20.18)
Ciprofloxacin	25 (12.25)	15 (30.61)	10 (9.17)
Streptomycin	37 (18.14)	N/A	13 (11.93)
Pefloxacin	12 (5.88)	10 (20.41)	7 (6.42)
Chloramphenicol	30 (14.71)	7 (14.29)	13 (11.93)
Sulfonamide	25 (12.25)	6 (12.24)	2 (1.83)

 

Table 5: Prevalence of antibiotics resistance among animals.

Antibiotics	Susceptible (%)	Intermediate (%)	Resistance (%)
Rifampicin	15 (13.16)	2 (16.67)	0
Gentamycin	12 (10.53)	N/A	5 (100)
Erythromycin	17 (14.91)	0	0
Ciprofloxacin	12 (10.53)	5 (41.67)	0
Streptomycin	17 (14.91)	N/A	0
Pefloxacin	8 (7.02)	4 (33.33)	0
Chloramphenicol	17 (14.91)	0	0
Sulfonamide	16 (14.04)	1 (8.33)	0

 

Among the livestock sampled, rate of MRSA isolation was highest in sheep. This agrees with the work of Gulani et al. (2016) which stated that among livestock and animal handlers, sheep recorded the highest. However, a study in Maiduguri in 2016 disagrees with this study; it stated a lower isolation of MRSA in sheep (4.6%) than other ruminants (Mai-siyama, 2014). In France, relatively high prevalence of MRSA among cattle (44.8%) was recorded, in Tunisia (29%) and Saudi Arabia (21.8%) (Gharsa et al., 2012).

Originally it was thought that MRSA transmission was basically from human to animal, with MRSA colonization and infection occurring through contact between human hands and anterior nares of the animal. There is now increasing evidence that MRSA can be transmitted in both directions; zoonosis and reverse zoonosis that is from animal to human and human to animal respectively. When animals get exposure to and colonized by MRSA, they could become reservoir hosts of this organism to other animals and their human handlers (Weese, 2005). Possible transmission and dissemination of the MRSA isolates could occur through contact which includes proximity through rearing and treating, domestication, nasal dropping during movement within the community and contamination of the meat by infected handlers (Lee, 2003). Livestock associated MRSA can enter a hospital setting through people with nasal colonization or through in-patients who needed treatment for MRSA infection according to Cuny et al. (2015). The Cuny et al. (2015) study confirmed a rise in livestock associated MRSA in hospital setting in Germany from 14% in 2008 to 23% in 2011. An outbreak can be the outcome in nearby communities as well as livestock farm, if not controlled. The implication is the circle of infection and reinfection of MRSA within and outside livestock farms increases the difficulty of treating diseases caused by this methicillin resistant organism in livestock and humans. Therefore, to increase preventive measures of MRSA colonization, the use of masks and hand gloves can be considered knowing that transmission of S. aureus occurs primarily through contact from hand to nose.

From Table 2, there is no statistical significant difference between the prevalence of MRSA in male and female students which is consistent with the findings of Rodriguez et al. (2014) and Fan et al. (2016). However, there was statistical association between the prevalence of MRSA in livestock, and students. It was also discovered that there was a strong linear correlation between MRSA in livestock, and students indicating that the MRSA increase in livestock results in an increase in students’ getting infected. This is in line with the findings of Ye et al. (2016) that pig workers carried MRSA and MDRSA isolates with multiple markers of livestock-association (tetracycline-resistance, IEC-negative, and CC9). Prospective studies are needed to investigate MRSA transmission between animals and humans and implement preventive measures.

The results of overall antimicrobial resistance (AMR) to other antibiotics showed Gentamycin to nave the highest prevalence of 31.19% for among students and 100% for livestock. A study agreed with a higher frequency of Gentamycin and Erythromycin resistance (Shibabaw et al., 2014). However, it contradicts the work of Garoy et al. (2019) where Gentamycin had 1.2%. Isolation of multiple drug resistance S. aureus has over the years been connected with the abuse of antibiotics, contact with livestock, and low standard of infection control, and prevention practices in Nigeria (Aiken et al., 2014). In addition, S. aureus isolates from students were resistant to more number of antibiotics than those of livestock. This is in agreement with the work of Castillo et al. (2014) which stated that the reason may be nontherapeutic use of antibiotics in food-animal rearing.

However, susceptibility pattern of S. aureus isolates from students indicated that the isolates were highly susceptible to Rifampin (18.63%), Streptomycin (18.14%), Chloramphenical (14.71%), Sulfonamide (12.25%) and Pefloxacin (5.88%). Resistant pattern showed Gentamycin to be highest (31.19%) followed by Erythromycin (20.18%) and the least was Sulfonamide (1.83%). There was more percentage resistance to the antibiotics used than the percentage susceptible. The isolates from animals were very susceptible to the antibiotics used. This study highpoints the importance of regular surveillance of antibiotic susceptibility pattern of S. aureus and MRSA to select appropriate therapy.

In considering the result of the study the prevalence of MRSA in livestock and students in the College of Animal Health and Production Technology using chi-squared test of independence and a P-Value of 5% significant level, X2=7.939, P=0.047 the alternative hypothesis was accepted, meaning there is an association between the prevalence of MRSA in livestock and students.

The correlation coefficient between prevalence of MRSA in livestock and students is +3 which show a strong positive correlation. The increased in MRSA in livestock also lead to the increased in students MRSA and vice versa.

One of the major limitation to this work is that molecular analysis of samples was not done. This would have enabled confirmation of strains from human sample to be of animal origin or vice versa. Further work is advocated on this.

Conclusions and Recommendations

Veterinary and animal production students are at increased risk of being MRSA reservoirs and could lead to zoonotic transmission to human populace outside the academic environment leading to Community Associated - MRSA (CA-MRSA). Therefore, MRSA colonization should be considered an occupational risk for members of the veterinary, animal health and production team – staff and students inclusive, particularly those in large animal practices. In addition, these professionals should be educated on the risk of MRSA transmission from livestock, and their environment. To add to the robustness of this work, differentiating human from livestock associated MRSA should further be done using molecular markers.

Acknowledgements

We are grateful to the management of Federal College of Animal Health and Production Technology, Vom for approving the collection of samples from students and livestock. Staff members of Microbiology Laboratory of the College are appreciated.

Authors’ Contributions

KNA developed the concept, wrote the protocol, supervised the bacteriological assays, carried out the data analysis and drafted the manuscript. JJK collected the samples and participated in carrying out the bacteriological assays. CAL participated in the final proofreading of the manuscript, engaged in bacteriological assays and contributed in the interpretation of the result. KNO participated in the final proofreading of the manuscript, engaged in bacteriological assays and contributed in the interpretation of the result. All authors read and approved the final manuscript.

Conflicts of interest

The authors declare that they have no conflict of interests.

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