The aim of this work, conducted between February and May 2019, was to evaluate the impact of hospitalization on colonization by methicillin-resistant Staphylococcus aureus among patients interned in the surgical department of a few health facilities in Ndé division.
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-imidazoles and β-lactams. 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 Staphylococcus at admission and discharge. 16 (28.07%) Staphylococcus aureus isolates were obtained at admission versus 25 (47.17%) at discharge. This result could be justified, at least in part, by a deselection of coagulase-negative Staphylococcus in favour of Staphylococcus aureus. But the mechanisms and conditions conducive to this selection are far from being clarified in the present work.
From the study of susceptibility profiles of isolates to the antibiotics used and more specifically to methicillin (highlighted in the present work using oxacillin and cefoxitin), it appears that resistance rates recorded at discharge were higher than those observed at admission. Indeed, proportion of nasal carriage of methicillin-resistant Staphylococcus aureus at discharge 16 (30.77%) was significantly higher than at admission 07(13.46%) with p = 0.0335. This result could be justified by the mobility of genetic factors, favoured both by the selection pressure imposed by broad spectrum antibacterial agents and the flexibility of the bacterial genome. These same factors could explain the multiple resistances regularly reported [9, 10] in accordance with the results of this study [9, 10, 12, 17,18,19,20].
Between admission and discharge, significant differences (p < 0.0001) concerning susceptibility profiles had been observed for antibiotics belonging to the β-lactams family (cefoxitin, oxacillin and penicillin G). This significant difference was in favour of a 4 times, 3 times and 2 times respectively higher resistance at discharge. This result could be justified by the direct effect of the use of antibiotics belonging to the β-lactams family (most commonly used antibiotics) in the selection and expression of resistance genes such as the mec A gene, which codes for methicillin resistance and induces resistance to practically all antibiotics in the β-lactams family. [1, 20,21,22,23].
These resistances are an alert as to the difficulty that would exist in managing a resistant infection and the need to use an antibiotic susceptibility test for therapeutic choice (personalization of management) with the antibiotics available and accessible in the target hospital settings in this work.
This result could be justified at least in part by a flaw in the respect of hygiene rules and the importance of the selection and dissemination of multi-resistant bacteria in the hospital environment.
Emergence and dissemination of bacteria resistant to antibiotics in hospitals as demonstrated in this investigation is an indirect indicator of the increasing additional cost to the patient. Given the standard of living and purchasing power, this evolution of resistance would be seen as a factor aggravating poverty through prolonged hospital stay and the cost of care. Taking into account the susceptibility profile at the patient's entry could be a major asset for drug management using antibiotics.