Introduction
Healthcare-associated infections (HAIs) occur in patient care settings, especially in hospital environments. With the rapid increase and widespread proliferation of multidrug-resistant (MDR) bacteria, the control and prevention of HAIs remains a challenging health problem. HAIs are caused by viral, fungal, and bacterial pathogens, such as Staphylococcus aureus, Pseudomonas aeruginosa, and Pseudomonas stutzeri. P. stutzeri is a nonfluorescent denitrifying bacterium that is widely distributed among diverse ecological niches; however, it has been isolated as an opportunistic human pathogen [1]. We witnessed an increase in the incidence of P. stutzeri isolations from patient wounds across several wards in our medical center. Here, we discuss our observations and share recommendations for the avoidance of increased P. stutzeri incidence in hospital settings.
Case
In the plastic surgery department of our hospital, patients with soft tissue defects are treated with a daily disinfectant regimen, and a bi-weekly wound swab culture is performed. After May 2016, the incidence of P. stutzeri isolations rapidly increased in patients with soft tissue defects of various body parts. P. stutzeri was isolated from nine patients across three wards. Patient characteristics are presented in Table 1. The majority of the patients’ wounds were caused by burns or traumas, with two cases occurring because of postoperative soft tissue defects. All patients underwent wound sterilization treatment performed by a single plastic surgeon in the plastic surgery facility. When an increase in wounds contaminated by P. stutzeri was observed, the authors consulted the Infection Control Department of the hospital. The department hypothesized that the environment, disinfectant method, and medical staff within the plastic surgery facility could be the source of infection. Therefore, an investigation was conducted. The infection control department produced cultures using samples obtained from the wound dressing room environment, dressing products, and the doctor’s hands and gowns. Sterile cotton swabs containing the samples were streaked across a third of a blood agar plate. We found that P. stutzeri was isolated from the saline-soaked cotton dressing container and different strains were isolated from the dressing cart and doctor’s gowns (Table 2).
Therefore, since P. stutzeri was isolated from the saline-soaked cotton container, the disinfectant was believed to be the cause of the outbreak. After removing the contaminated container, we implemented a procedure to prepare fresh saline-soaked cotton each time a wound dressing was required. As a result, the incidence of P. stutzeri isolations decreased over the next two months (Figure 1).
Discussion
HAIs, also known as nosocomial infections, refer to infections that occur 48 hours after admission to medical institutions such as hospitals, nursing hospitals, and outpatient clinics [2]. HAIs do not include infections in the incubation period at the time of admission. Each year, millions of patients worldwide are affected by HAIs. Recently, incidences have been attributed to an increase in immunocompromised patients and the generalization of invasive procedures, both of which often lead to extended periods of hospitalization, thereby increasing the mortality risk and medical expenses. Furthermore, a high incidence of infections are caused by MDR bacteria, such as methicillin-resistant Staphylococcus aureus (MRSA), vancomycin-resistant Staphylococcus aureus, and vancomycin-resistant enterococci [3]. HAIs are commonly caused by MRSA, Acinetobacter baumannii, and Pseudomonas aeruginosa, which can lead to urinary tract infections, postoperative surgical site infections, pneumonia, and soft tissue infections [4]. Less commonly, HAIs have been shown to be caused by P. stutzeri, an anaerobic, nonfermenting, active, gram-negative, oxidase-positive bacteria. P. stutzeri rarely induces community-acquired and nosocomial infections, yet HAIs caused by P. stutzeri involve pneumonia, meningitis, osteomyelitis, prosthetic knee infections, and soft tissue infections. In addition, P. stutzeri can lead to severe bacteremia in immunocompromised patients [5]. Therefore, epidemiologic studies are needed to improve monitoring and control of HAIs.
In this case report, the authors witnessed a sudden increase in the number of patients with P. stutzeri isolations despite application of the medical institution’s standard sterilization protocol. Nine patients had P. stutzeri-infected wounds, with five wounds caused by burns or trauma, two wounds caused by diabetes mellitus, and two wounds caused by postoperative soft tissue defects. For each case, cultures were obtained from the wound dressing room environment and products, including the saline-soaked cotton container, the potadine-soaked cotton container, dressing forceps, dressing carts, and dressing beds, and from the healthcare team, including the doctor’s hands and gowns. Results indicated that the strain of P. stutzeri originated exclusively from the saline-soaked cotton container. In addition, Gram-positive bacilli were found on the dressing cart and bed, and three colonies of Staphylococcus aureus and coagulase-negative staphylococci were detected on the doctor’s gown and hands, respectively. Therefore, the observed HAIs were caused by cross-contamination of sterile sites. These findings are supported by the reduction of P. stutzeri isolations once the contaminated container was removed and a procedure of preparing fresh dressings as needed was implemented. Our findings lend support to the new strategy implemented to reduce the incidence of HAIs.
In the intensive care unit, 40–60% of HAIs are caused by normal flora infections while 20–40% are caused by cross-infections from medical personnel [6]. The probability of nosocomial infections has decreased with the application of alcohol-based hand sanitizers and propagation of hand hygiene education [7]. However, despite wearing personal protective equipment, such as gowns and masks, and practising appropriate hand hygiene, doctors remain a primary conduit of HAIs because they are in frequent contact with patients and hospital environments [8]. This notion is supported by the findings of this case report because bacterial isolations were found on the physician’s gown and dressing cart. Therefore, medical institutions should consider infection control strategies to improve sanitization methods and environments.
However, this case report also revealed bacterial isolations in the dressing product, demonstrating the importance of appropriate wound care. Topical antiseptics, such as povidone-iodine, chlorhexidine, alcohol, acetate, hydrogen peroxide, boric acid, and silver nitrate are used in clinical practice [9]. Normal saline has been used typically for wet dressings because it is cheap and easy to apply, even though the solution has no antiseptic properties [10]. In this case, P. stutzeri was isolated from the saline-soaked cotton container, even though the solution and dressing were replaced and freshly prepared daily. However, because saline does not disinfect, harmful bacteria can multiply and be transmitted to other patients. Therefore, the authors eliminated the use of the dressing container and implemented a dressing procedure that administered saline solution on an individual, need-by-need basis. This new method eradicated the observed bacterial isolations.
Although bacteria of the same species were detected in the saline-soaked cotton container, a limitation of the present study might be that a single doctor performed the sterilization wound dressings in our case. This factor is significant because the bacterial contamination could have been a product of individual actions rather than institutional procedures.