Bacteriological assessment of the hospital environment in two referral hospitals in Yaoundé-Cameroon

Introduction Many studies still show significant numbers of surgical patients contracting nosocomial infections each year globally with high morbidity and mortality. The aim of this study was to identify potential bacteria reservoirs that may be responsible for nosocomial infection in surgical services in the Yaoundé University Teaching Hospital (YUTH) and the Central Hospital Yaoundé (CHY). Methods A cross sectional descriptive study was conducted from June to August 2012. Air, water, and surface samples were collected from two surgical services and subjected to standard bacteriological analysis. Results A total of 143 surface samples were collected. Bacteria were isolated in all surfaces except from one trolley sample and a surgical cabinet sample. The predominant species in all services was coagulase negative Staphylococcus (CNS). The average number of colonies was 132. 82CFU/25cm2. The bacteria isolated in the air were similar to those isolated from surfaces. From the 16 water samples cultured, an average of 50.93 CFU/100ml bacteria were isolated. The distribution of isolated species showed a predominance of Burkholderia cepacia. Conclusion These results showed the importance of the hospital environment as a potential reservoir and source of nosocomial infections amongst surgical patient at YUTH and CHY, thus we suggest that Public health policy makers in Cameroon must define, publish guidelines and recommendations for monitoring environmental microbiota in health facilities.


Introduction
Despite significant scientific progress in the field of surgery, anesthesia and the use of antibiotics, estimates showed that an average of 2.5% of the 6 million surgical patients visiting US health facilities each year contract a nosocomial infection [1]. These lead to the increased burden on both the patient and society [1][2][3][4].
Nowadays, the assessment of health facilities environment (air, water, surfaces) has become part of a good health care quality and safety policy, including the assessment of risk of infection in surgery where surgical acts are performed sometimes with high-tech tools [5]. The main objective of this study was to identify potential bacteria reservoirs that may be responsible for nosocomial infection amongst surgical patient at the Yaoundé University Teaching hospital and at the Central Hospital Yaoundé in Cameroon.
Specifically, the bacteriological quality of the air, water and surfaces in these health facilities was assessed.

Ethical Consideration
Administrative authorizations were obtained from the Director of YUTH (Pr Maurice Nkam) and from the former Director of the CHY (Pr Bella Hiag A). Ethical clearance was not applicable in the context of this study.

Surface assessment
Of a total 143 samples in which bacterial culture were processed, 83 came from YUTH and 60 from the CHY. Bacteria was isolated in almost all samples 141 (98.60%). The average number of colonies was 132.82 CFU/25cm 2 . With regard to the classification of different hospital areas and surfaces, using the bio-contamination index values, 16 (11.18%) samples showed a reasonable number of colonies/25cm2 with 5 of these from CHY whereas 11 were from YUTH. Out of a total of 148 bacteria isolated on surfaces, 85(57.43%) were from YUTH where as 65(43.91%) were from CHY. Table 1 showed that the predominant species identified in each service was coagulase negative Staphylococcus.  Table 2 below.

Discussion
The main aim of this study was to identify potential bacteria reservoirs that may be responsible for nosocomial infection amongst

Surface assessment
The findings in this study showed that the surfaces of the hospitals are heavily contaminated by bacteria with only 1.39% negative.
These results are similar to those obtained by Meunier and coworkers (2005) in a study carried out in Strasbourg where they obtained à 3% negative cultures [6].The findings also showed that the objects sampled host microorganisms. Many observations abound in the same direction and show that these objects in this environment are known to harbor microorganisms such as Staphylococcus, Enterococcus, Acinetobacter [7,8]. The results of the colony counts suggest that microbial colonization of surfaces in these two hospitals is far higher than standard surface biocontamination values [9]. One hundred and forty eight bacteria (148) were identified, with coagulase negative Staphylococcus (57.43 %) being the most predominant species in all the surgical services. These results are similar to those obtained by Tagnouokam in 2008, who found a predominance of CNS (55%) [10]. These findings also colloborate with several studies which showed that the various components of the hospital environment (air, water , surfaces, clothes , food , medical devices, waste ) can accommodate many microorganisms specifically from human or environmental origin [11,12]. According to Kim and co-workers, (1981), the inanimate areas around patients are normally contaminated by microorganisms [13]. The presence of microbial contaminants on the surfaces is also favored by the formation of biofilms and the ability of these bacteria to survive for a long time in the environment [14].

Air assessment
This study showed clearly that, after performing culture and bacteria isolation on hospital air samples collected in areas where the atmosphere is under control, the level of infectious risk was acceptable in YUTH but above alert level in CHY according to the ASPEC guidelines [15]. This constitutes a significant risk factor for the occurrence of surgical site infections. These results also show that the level of aerobiocontamination at operating rooms varies from one hospital to another. Studies have shown that the air contamination was due to poor maintenance of the ventilation system or its operation disrupted by frequent opening of doors or sudden movements [16]. Moreover, the outside air naturally contains some bacterial flora in hospitals and these outside air microorganisms add to those inside and to inert tanks (water, surfaces, waste) [17]. This aero-biocontamination level observed in CHY denotes a lack of personal discipline that integrates training on hand washing and managing the operation room. Although air samples were collected during inactivity in the operation room, we isolated 25 bacteria, 65.79 % of which were coagulase negative Staphylococcus. These results are comparable with those obtained in England where a gold standard method (impactation) was used.
Indeed, the authors in the British study reported that among the isolated bacteria, CNS (86%) was predominant [18]. It is also important to note here that the bacteria species identified in this study are frequently identified in bacteriological analysis of the hospital environment [19]. According to the frequency of bacteria  co-workers (1983, 1985) have shown the relationship between the air quality in operation room and surgical wound infection occurring in prosthetic orthopedic surgery [20,21].

Water assessment
Seventy five percent of water samples were culture positive.
Considering the recommendations on the measurement of water biocontamination according to the ISO 19458 standard [22,23], all the positive cultures had more than 1 CFU/100ml. This points out the fact that the use of water for standard care in these health facilities is a health risk and that ways must be identified to manage  Humphrey (1989) showed that the basic gestures such as nasogastric tubes care and bathing can create aerosols and thus are sources of hospital contamination [26].
Overall, comparing the findings in this study with those of Verdeil and co-workers (1990) conducted in Toulouse France clearly suggest a significant correlation between the contamination of the hospital environment and the recovery of bacteria on surgical patients [5].

Conclusion
The results from this study provide evidence for directly incriminating the hospital environment as a potential bacteria reservoir for nosocomial infections in the surgical patients at YUTH and CHY, thus we suggest that Public health policy makers in Cameroon must define, publish guidelines and recommendations for monitoring environmental microbiota in health facilities.

Competing interests
The authors declare no conflict of interest.