UTIs are the second most common postoperative complication of patients treated in orthopedic wards, more common than deep venous thrombosis, pneumonia or renal failure [11, 1]. The risk of major postoperative complications such as surgical site infections (SSIs) after orthopedic surgery is estimated from 1.4% to over 20%. In the studied center, SSI incidence rate was 6.6%, about 6 times higher as compared with European HAI-Net .
Unfortunately, the presented data indicate that in the studied department, the epidemiology of the UTI is also a significant problem, e.g. according to the data of the American NHSN program regarding the departments of orthopedics and traumatology, CA-UTI incidence density was more than three times lower . In the European ECDC infection surveillance program, the CA-UTI incidence rate was 4.1 per 1000 patient-days, hence it was more than twice lower than in the examined ward – in spate that it concern intensive care units .
The data obtained in this study are also significantly higher than in another comparable hospital in Poland .
Unfortunately, the problem may have been the bladder catheterization procedure used in this ward, which has never been validated, hence the conclusion about the need for systematic surveillance regarding UTIs identification, but also infection prevention and control, especially for indwelling catheters, i.e. insertion and hygiene [25, 24]. An example would be the intervention described by Takker et al. in the surveillance of patients undergoing total hip and knee replacement and hip fracture treatment, where morbidity was reduced from 2.1–1.1%. The intervention involved the implementation of catheter surveillance principles, including qualification for catheterization, which resulted in a reduction in the number of procedures from 55.2–19.8% . Our presented data indicate a significantly higher proportion of catheterized patients, which is probably the result of overusing this procedure, not only in intraoperative but also in postoperative period.
In case of orthopedic patients, it has been shown that the proper use of perioperative antibiotic prophylaxis in accordance with local decision-making standards improves the patient's prognosis in terms of SSIs and additionally also in the prevention of CA-UTIs . Indwelling catheters can increase postoperative urinary tract infection and may not be required in total joint arthroplasty . Based on the current evidence, the urinary catheterization during total joint arthroplasty increased the postoperative CA-UTIs, and it may not be routinely required for patients undergoing such procedures.
On the other hand, however, postoperative complication is urinary retention, especially common after anorectal and hernia surgery and after orthopedic surgery [4, 2], hence withdrawal of routine perioperative catheter use may prove difficult in practice, especially in the elderly patient population, because the risk increases with the patient's age.
In addition to the catheterization procedure itself, many other factors contribute to the development of UTI, including patient-dependent unmodifiable factors, with age that is a particularly strong predictor of UTI. This is confirmed by other authors [1, 14] as well as by presented results, which indicate a significant, more than 3-fold higher risk of infection in patients aged 75 years and older. One of the conditions may be a generally weaker immune response in older patients, but also a weaker physical condition or limited mobility. Consideration should be given to HAI surveillance by introducing special HAI exposure alert among various other elements of HAI – including UTIs prevention and control in orthopedic departments, using the generally accepted scale for geriatric patients, e.g. the Bathel scale, used to assess patients' mobility. Such a stratified description of patients would facilitate the implementation of special surveillance of persons exposed to HAIs.
Typical microbial virulence factors are important in CA-UTI pathomechanism, especially formation of abundant biofilm and urease responsible for increasing urine pH and accompanying precipitation of urinary stones. These features are present in the Pseudomonas aeruginosa, Klebsiella pneumoniae, Morganella morganii, Proteus mirabilis and some Providencia spp. infections. Also some strains of Staphylococcus aureus and coagulase-negative staphylococci [18, 22]. Thus, the dominance of Enterobacterales Gram-negative bacteria [11, 19, 23] in presented study is not a cause for concern.
However, the described low drug sensitivity is a big problem. Especially resistance to quinolones and extended spectrum cephalosporins remains a major challenge, because these antibiotics are widely used as first-line therapy in the treatment of UTIs. Particular consideration should be given to penicillins sensitive to beta-lactamases (due to the high proportion of ESBL + strains) and fluoroquinolones, which significantly limits the available therapeutic options. CTX-M ESBLs are becoming more common worldwide, especially CTX-M-15, often associated with the uropathogenic E. coli clone. In addition plasmids, that are often carrying ESBL genes also carry determinants of fluoroquinolone resistance . Therefore, the use of both ciprofloxacin - a drug common in empirical therapy of UTIs, as well as eagerly used empirically in Poland, for bladder infections - trimethoprim / sulfamethoxazole, carry the risk of therapeutic failure.
The matter gets complicated by the high prevalence of MDR strains, especially non-fermenting Acinetobacter baumannii and Klebsiella pneumoniae, which account for about 1/4 of all UTIs [12, 16]. The studied department, unfortunately, represents a very typical ward. According to data from Mazzariol et al.  from 2014 in EU / EEA countries the percentage of ESBL (+) K. pneumoniae resistant strains in UTIs was even over 70% (Romania, Grece), and ESBL (+) E. coli over 40% (Bulgaria). In Poland, above ESBL (+) strains constituted 65% of K. pneumoniae strains and 11% of E. coli. In the countries of Northern Europe (Finland, Iceland), the prevalence of this type of resistant strains is significantly lower . Unfortunately, in the studied unit the high prevalence of MDR microorganisms was observed not only in UTIs, but also in surgical site infections: 22.6%, and also mainly concerned the Gram-negative bacilli: Acinetobacter baumannii and Klebsiella pneumoniae .
The limitation of our study was retrospective rather than prospective UTI analysis and limited ability to compare our results with various local antibiotic sensitivity patterns in the UTI orthopedic patient population, due to the lack of comparative data – non-SSI infections in patients after orthopedic surgery are poorly described.