Hospitalization and colonization by methicillin-resistant Staphylococcus in the surgical department in 03 health facilities of the Ndé division, west-Cameroon CURRENT STATUS: POSTED

Background: Commensal flora colonization during hospitalization by bacteria is the first step for a nosocomial infections while antibiotic resistance reduces therapeutic options. In aim to control this phenomenon, we initiated this study to describe the impact of hospitalization on colonization by methicillin-resistant Staphylococcus in the surgical department in 03 health facilities of the Ndé division, west-Cameroon. Methods: This quasi-experimental study was carried out on patients admitted for surgery in 03 health facilities of the Ndé division, west-Cameroon (District Hospital of Bangangté, Protestant Hospital of Bangwa and Cliniques Universitaires des Montagnes). After obtaining ethical clearance and authorizations, nasal swabs were performed at admission and discharge, with the aim of isolating bacteria and performing their antibiotic susceptibility tests. Information on each participant's antibiotic therapy was recorded. Laboratory investigations were carried out according to standard protocols (CASFM, 2019). Results: The most commonly used antibiotics were β-lactam antibiotics. Of the 52 patients who agreed to participate in the study, 104 nasal swabs were performed. From the analysis, 110 (57 at admission versus 53 at discharge) Staphylococcus isolates were obtained. Overall, susceptibility testing showed that antibiotic resistance rates were higher at discharge than at admission; with significant differences between the susceptibility profiles obtained at admission and discharge for β-lactam antibiotics and not significant for fluoroquinolones and aminoglycosides. The nasal flora of 13 (25%) patients was colonized with methicillin-resistant Staphylococcus at admission versus 39 (75%) at discharge and 14 (24.56%) of the isolates obtained at admission were methicillin-resistant versus 37 (69.81%) at discharge. Of the variables studied, hospital stay remained the only variable significantly ( p =0.0080) associated with colonization by methicillin-resistant Staphylococcus . Conclusion: This work must be considered as an alarm bell regarding the role of health structures in the colonization and spread of multi-resistant bacteria in Ndé division. As a result, further investigations aimed at investigating the factors favouring this phenomenon should be carried out with an approach similar to that of the ONE resistance obtained at admission and at discharge of patients. Logistic regression analysis uni-variable and multi-variable was used to identify determinants of methicillin resistance by Staphylococcus strains . The analysis were performed using 95% as confidence interval and 5% as degree of significance.

recommend strict compliance with hygiene rules, personalized antibiotic therapy (performing antibiotic susceptibility tests) and an updated antibiotic prophylaxis and probabilistic antibiotic therapy according to the studies carried out in the locality.

Background
Staphylococcus are Gram-positive cocci bacteria found on the surfaces of our environment, as well as on the skin and mucous membranes (nasal mucosa) of humans [1,2]. Mutualist bacteria in humans, they can be pathogenic when the balance is disrupted, in fact in the presence of a decrease in immunity/injury, these bacteria can cause a multitude of diseases (sepsis, impetigo, endocarditis etc....) more or less severe while antibiotic resistance reduces therapeutic options. Methicillin resistance was observed in Staphylococcus strains in health facilities around 1961 after the introduction of methicillin, reflecting the role of health facilities in the selection and dissemination of antibiotic-resistant infectious agents [3]. This resistance results from the expression of the resistance genes such as the mec A gene, which induces resistance to almost all β-lactamins among Staphylococcus strains [3].
Studies on bacterial resistance in hospitals, more specifically on methicillin-resistant Staphylococcus (MRS) strains, have highlighted the acquisition of multi-resistant bacteria during hospital stay and the harmful consequences of these multi-resistant bacteria on patient's lives [4][5][6]; thus justifying the inclusion of the fight against bacterial resistance to antibiotics in global programs (Global Health Security Agenda, One Health) [7,8]. Also, several studies carried out throughout the world, in west Cameroon and more specifically in the hospitals of the Ndé division have shown that the hospital environment (mainly in surgery) is an environment conducive to the selection and dissemination of multi-resistant bacteria on one hand and to the exchange of genetic material between the bacteria in this environment and those in the human body on the other hand [9][10][11][12][13].
Management with antibiotics would become increasingly difficult as the length of hospital stay increases. Data useful for understanding this phenomenon of growing antibiotic resistance that threatens patient care are scarce around the world and particularly in developing countries where resources (human and financial) for research are limited. However, it is imperative to understand the evolution of these phenomena in order to address the morbidity and mortality that occur as a consequence of antibiotic-resistant bacterial infections. It is in this context and with the aim of making a modest contribution to global programs (Global Health Security Agenda, One Health) focused on the fight against antibiotic resistance that this work was initiated. In order to study the impact of hospitalization on colonization by MRS in patients interned in the surgical department of 03 care setting in the Ndé division. The results of this work will guide patient's antibiotic therapy (antibioprobabilistic) at admission and during hospitalization, and will provide a basis for implementing and evaluating strategies and policies to reduce the proportion of resistant bacteria among patients during their hospital stays and thus limit nosocomial infections. This will be done with a view to reducing the emergence of multi-resistant strains in hospitals and their spread from hospitals to the community.

Study site, populations and sampling
This study was a quasi-experimental study conducted from February to May 2019 in patients from admission to discharge in three health facilities of the Ndé division, west-Cameroon (District Hospital of Bangangté, Protestant Hospital of Bangwa and Cliniques Universitaires des Montagnes). When all administrative and ethical requirements were met, nasal swabs were performed by streaking both anterior nares with sterile moistened cotton swabs among patients whose consent was given. Nasal swabs were placed in labelled tubes containing heart-brain broth, stored in an icebox (2-8 o C) and transported without delay to the Laboratory of Microbiology of Cliniques Universitaires des Montagne for processing.

Bacterial isolation and identification
After seeding and 18-24 hours culture on selective culture media (Manitol salt agar), isolation and identification of Staphylococcus strains were based on cultural characteristics, Gram staining, catalase test, coagulase test and DNase test after performed sub-culture on nutritive agar.

Antimicrobial Susceptibility testing
The susceptibility testing of bacterial isolates against antibiotics was performed by the disk diffusion method (Kirby-Bauer method) on Mueller Hinton agar according to standard procedures recommended by "Comité d'Antibiogramme de la Société Française de Microbiologie (CASFM 2019)" [14]. After sub-culture on nutrient agar (during 24 hours at 37°C ) of a colony isolated on selective media (Manitol salt agar), the bacterial pure culture obtained has been used to perform a suspension in 0.9% saline with density equal to that of the McFarland (0.

Detection of methicillin resistance Stahylococcus
The phenotypic method based on susceptibility of oxacillin (1µg) and cefoxitin (30µg). The tests were concurrently performed with susceptibility testing of each isolate. Reference strains S. aureus ATCC 700699 and ATCC 25923 were used as a positive and negative control, respectively.

Data analysis
The data collected in this study were recorded in Microsoft Excel 2016 software and analyzed using StatView5 software. Descriptive analysis were carried out on the study variables, which included computation of addition and frequencies. A chi-square test was used to compare the susceptibility profiles and frequency of methicillin resistance obtained at admission and at discharge of patients.
Logistic regression analysis uni-variable and multi-variable was used to identify determinants of methicillin resistance by Staphylococcus strains. The analysis were performed using 95% as confidence interval and 5% as degree of significance.

Characteristics of study participants
During the study period from February to May 2019, 52 patients participated in the study. The age of the latter ranged from 5 to 79 years with a mean of 40.77 years. Patients were hospitalized for 3 and 22 days with a mean of 7.58 days. The characteristics of this population are summarized and presented in Table I. First of all, it appears that men accounted for almost 3/4 of the population. Similarly, visceral surgery was the most frequent type of surgery with a proportion of 3/4. Finally, the antibiotics most commonly administered to patients belonged to the families of nitro-5-imidazole and β-lactamines with proportions approximately equal to 4/5 and the antibiotics least administered to patients belonged to the family of macrolides with a proportion of 1/50.

Distribution of bacterial isolates
From admission to discharge from hospital, 104 samples were taken. From these analysis, 110 Staphylococcus isolates were obtained. Of these, 57 isolates were obtained at admission versus 53 at discharge. The distribution of Staphylococcus isolates is presented in Table II. The results presented in Table II show a significant variation between Staphylococcus aureus strains and coagulase negative Staphylococcus strains isolated at admission and those isolated at discharge.
Indeed, at admission Staphylococcus aureus represented practically 1/4 of the strains of Staphylococcus compared to approximately 1/2 at discharge.

Antibiotic susceptibility profiles of Staphylococcus isolates
The susceptibility profile of Staphylococcus isolates obtained at admission and at discharge is presented in Table III. n admission : number at admission ; n discharge : number at discharge. Table III shows that overall, the resistance rates obtained at discharge were higher than those obtained at admission. Significant and insignificant differences between the susceptibility profiles of the isolates obtained at admission and discharge were observed.
Significant differences were observed (p˂0.0001) for β-lactamines: cefoxitin, oxacillin and penicillin G in favour of a higher proportion of resistance to these antibiotics at discharge than at admission, resulting in resistance proportions respectively 4 times, 3 times and 2 times higher at discharge. In contrast, insignificant differences were mainly observed for fluoroquinolones (ciprofloxacin and norfloxacin with p=0.0624, p=0.0749 respectively) and cotrimoxazole (p=0.9878).

Distribution of methicillin-resistant Staphylococcus isolates
A systematic screening of methicillin-resistant Staphylococcus isolates was performed during the interpretive reading of the antibiotic susceptibility test. Overall 13 (25%) of patients were colonized by methicillin resistant Staphylococcus at admission versus 39 (75%) at discharge. The results of distribution of methicillin resistant Staphylococcus obtained at admission and at discharge are presented in Table IV. From Table IV, it appears that the proportion of methicillin-resistant Staphylococcus isolates obtained at discharge from hospital was almost three times that obtained at admission with a significant difference (p˂ 0,0001).

Research of the factors associated to colonization by MRS
In order to determine the factors associated to colonization by MRS, variables were identified and univariate analyses were first performed. Those who had presented a p≥ 0.20 were selected for the multi-variate analysis. The results of the latter are summarized and presented in Table V.

Discussion
The aim of this work, conducted between February and May 2019, was to evaluate the impact of hospitalization on colonization by methicillin resistant Staphylococcus in patients interned in the surgical department of a few health facilities.
The majority of patients were male (3/4). This could be justified by the fact that they are the most regularly involved in hazardous activities, requiring great physical effort and therefore more frequently victims of accidents of all kinds. These activities expose them to accidents that can only be remedied by invasive acts such as surgery. This view is shared by the proportion of visceral interventions for hernias. Other causes that are not clear from this work but which are most probably at the origin of internalizations in surgical departments include road accidents and those associated with other high-risk professions.
Data analysis indicated that more than 80% of the most commonly administered antibiotics to patients were nitro-5-imidazol and β-lactamines. Several reasons could explain this rate of use: 1.
these antibiotics have a wide spectrum of action on several bacterial types, have good tissue diffusion and are the most available and accessible in hospital pharmacies; 2. the less frequent adverse reactions (toxicity) to their administration encourage their choice in the management of patients during prophylaxis and anti-infectious therapy [15,16]. This development is further supported in the present work by the rates of use of other antibiotics (macrolide), which are certainly lower in relation to their relatively limited spectrum of Gram-positive bacteria and high toxicity [15].
Different frequencies were recorded for Staphylococcus aureus and coagulase-negative

Conclusions
At the end of our investigation, the aim was to evaluate the impact of hospitalization on colonization by methicillin-resistant Staphylococcus in patients interned in the surgical department of 3 care setting in the Ndé division. From this, it appears that the rates of antibiotic resistance of Staphylococcus strains isolated at discharge were globally higher (mainly with regard to antibiotics belonging to the β-lactamine family, the most used family) than those obtained at admission and that colonization by methicillin-resistant Staphylococcus was more important at discharge than at admission. It should be noted that the search for factors that could be significantly associated with colonization by methicillin-resistant Staphylococcus in the present work was limited to factors directly related to patients and their management (surgery and antibiotics administered). Although this aspect can be considered as a limitation, it does not detract from the quality of this work, which must be considered as an alarm bell with regard to the emergence and spread of resistant bacteria in Ndé division. As a result, further investigations to find the factors that promote this phenomenon should be carried out with an approach similar to that of the ONE HEALTH concept.

Consent for publication
Not applicable.

Availability of data and materials
All data generated or analysed during this study are included in this published article.