The prevention and control of hospital-acquired or healthcare-associated infections (HAIs) are essential components in the functioning of a healthcare facility. HAIs are defined as infections contracted in a hospital or any healthcare facility after at least 48 hours of hospitalization. The impact of HAIs, also in relation to their contagiousness, is really demanding in terms of morbidity and mortality, being associated with prolonged hospital stays and a significant financial burden.
The incidence of HAIs is scarcely documented in veterinary healthcare facilities (VH), but according to a past survey on 38 AVMA accredited veterinary teaching hospitals, at least 1 outbreak was reported in 31/38 (82%) facilities, with 17 (45%) reporting more than 1 outbreak in a 5-year period. Restriction in patient admission (58%) and closure of some part of the facility (32%) were the measures adopted to control infection spread. The overall incidence of HAIs is supposed to be on the rise and run in parallel with the increment of susceptible patients and invasive procedures performed in VH. Furthermore, the latter is not always designed according to biosecurity requirements and limited resources are dedicated to infection prevention and control programs (IPC).
The chain of infection allowing the spread of the disease within the hospital includes six key elements linked together: susceptible host, pathogen, reservoir, portal of entry, mode of transmission, and portal of exit. Breaking any one of the links can hinder the spread of the infectious disease.
Generally, microorganisms associated with HAIs are commensal opportunistic pathogens, frequently undergoing a strong selective pressure due to overuse of antimicrobials in hospitals and, therefore, being multidrug-resistant (MDR). Pathogens of concern in healthcare facilities include methicillin-resistant Staphylococcus aureus (MRSA), ESBL-producing Enterobacteriaceae, Enterococcus spp., Klebsiella pneumoniae carbapenemase (KPC), Pseudomonas aeruginosa, and Acinetobacter spp. with rates of isolation varying among countries or facilities according to different socio-economic conditions, risk factors, financial investments on ICP, as well as different laws and policies on antimicrobial use and prescription.
It is worth noticing that pathogens involved in HAIs might harbor a zoonotic potential and be transmitted either way between humans (staff, owners) and animals, underlying if needed, the opportunity of a “one health” approach in the infection control practice in healthcare facilities.
The most susceptible hosts to causative pathogens of HAI are small animals hospitalized in an intensive care unit (ICU), while the most common sites of infection are the following: urinary tract, lungs, bloodstream, surgical site, and gastrointestinal tract. The incidence rate of HAIs in ICU small-animal patients is reported to be 12–16% over a period of 12 weeks. Patients hospitalized in the ICU have a risk up to 10 times higher of contracting an HAI compared to non-critically ill hospitalized animals. Furthermore, ICU patients have a greater likelihood of being colonized with MDR bacteria (e.g., E. coli) during the hospitalization, regardless of antimicrobial treatment. Intrinsic and extrinsic factors potentially associated with HAIs include: systemic inflammation, immunosuppression, poor body condition score, use of invasive medical or surgical devices, and widespread use of antimicrobials (e.g., fluoroquinolones).
Catheter-associated urinary tract infections (CUTI) are probably the most common HAIs in small animals. The normal defense mechanism of the urinary tract is hampered by the presence of the catheter allowing bacterial colonization of the device itself and the ascension of microorganisms to the bladder. Pathogens involved in CUTI might include microorganisms resident of the perineal region or nosocomial ones transmitted by the staff for an improper technique of urinary catheterization or through contamination of the urinary bag and the drainage system. Moreover, the tip of the urinary catheter might be a preferential site of bacterial biofilm formation. Bacterial biofilms are clusters of bacteria embedded in a self-produced matrix, able to attach to the surfaces of medical devices, evading the host defense systems, reducing antimicrobial penetration, and facilitating device-associated infections. Thus, permanent urinary catheterization should be performed only when strictly necessary, using a sterile technique, and a closed-circuit system for urine drainage and collection.
Fever of unknown origin, without clear evidence of a septic focus, is not an uncommon event in hospitalized patients with either long-term or short-term intravascular devices, and might be associated with bloodstream infections (BSI). Risk factors for BSI include administration of hypertonic solutions (glucose, propofol, parenteral nutrition), presence of a multilumen central venous catheter (CVC), longer permanence in situ of CVC, and the condition of immunosuppression. In case of a suspicion of BSI, intravascular devices should be removed and a culture of the tip of the catheter, as well as a blood culture, should be submitted. An empirical antimicrobial treatment should be directed toward pathogens commonly isolated in the healthcare facility according to the periodic data of prevalence reported.
Surgical site infections (SSI) are classified as: superficial, occurring within 30 days from a surgical procedure involving only the skin and subcutaneous tissues of incision; deep, occurring within 30 or 90 days, according to the procedure, and involving deep soft tissues of the incision; organ/space infections, occurring within 30 or 90 days, according to the procedure, involving an organ or cavity distant from the incision site. Epidemiological data relative to SSI in veterinary medicine are probably underestimated, mainly due to the retrospective nature of the studies, lacking a consensus on SSI definitions, and the fact that superficial infections are rarely reported. Risk factors reported to be associated with SSI include: hypotensive episodes during operation, type of surgical wound classification and presence of an implant, length of anesthesia and surgical procedure, increasing number of persons in the operation room, and postoperative body temperature. The compliance of the surgeon is the most effective measure in the prevention of SSI, if a strict and appropriate observation of the procedures of hand hygiene, surgical site preparation, and preservation of sterile equipment are guaranteed.
Hospital-acquired pneumonia might include ventilator-associated pneumonia (VAP) and aspiration pneumonia, which can occur in hospitalized patients with a wide range of disorders. VAP occurs at least 48 hours after endotracheal intubation and mechanical ventilation, and is normally associated with colonization of the oro-pharynx by MDR enteric bacteria or nosocomial ones, which might get access to the lower respiratory airways due to a decreased mucociliary clearance and an impaired immune system. Ileus, constipation, gastroesophageal reflux, laryngeal or esophageal disorders, recumbency, or depressed mentation are all potential contributing factors to aspiration pneumonia, which is a more frequent complication reported in hospitalized animals.
The institution of an ICP in a healthcare facility is a key element in monitoring and contrasting the occurrence of HAIs. Preventive measures are the most effective means to break the chain of infections and reduce the incidence of HAIs. Personal hygiene and protection, including hand hygiene and use of personal protective equipment, should be associated with standardized procedures of sanitization of the hospital environment and proper isolation and cohorting of patients according to the infectious risk.
ICP should include surveillance systems (active, targeted, passive, or syndromic) finalized to monitor health events, prevalence of antimicrobial resistance, and other potential risk factors associated with HAIs. Moreover, a coordinated antimicrobial stewardship policy in the VH should guide the appropriate use of antimicrobials to maximize their benefit, while causing the least harm. Periodic monitoring reports for the presence of MDR bacteria can assist in the timely notification of cases or outbreaks. During an outbreak, specific measures of intervention should be applied, ideally coordinated by a dedicated team, and appropriate infection control strategies should be implemented. Finally, education and training of hospital staff, including students, promoting awareness on the relevance and impact HAIs, is a key element of an ICP.
References
References are available upon request.