Do Changes in Antimicrobial Resistance Necessitate Reconsideration of Surgical Antimicrobial Prophylaxis Strategies?

A Six-Year Retrospective Study of Microbiological Characteristics and Antimicrobial Resistance in Specimens from a Tertiary Hospital’s Surgical Ward

Surgery has revolutionized the practice of medicine by allowing the treatment of conditions amenable to conservative medical management with some of them pathophysiologically involving the prevalence of pathogenic microorganisms. On the other hand, infections such as surgical site infections or urinary tract infections may complicate patients hospitalized in surgical wards leading to considerable morbidity, mortality, and increased healthcare-associated costs. The aim of this study was to present the microbiological characteristics and antimicrobial resistance of all isolates identified in microbiological specimens from a surgical ward of a tertiary hospital in Greece during a six-year period. Only specimens that yielded at least one microorganism were included in the analysis. In total, 1459 strains in 789 positive cultures were isolated. The most common sample sent to the microbiology department was pus from surgical wounds. The most common pathogens among all 1459 strains isolated were Enterobacterales at 33% (n = 482), however, the most common genus was Enterococcus at 22.3% (n = 326). Antimicrobial resistance against third-generation cephalosporins was 23% (n = 111/482) among Enterobacterales, while, the rate of vancomycin-resistant enterococci (VRE) was 18.5% (n = 60/324) among Enterococcus species and was increasing in the last years of the study. Antimicrobial resistance of Acinetobacter baumannii to carbapenems was 68.8% (n = 11/16), which was lower than the corresponding rate in other wards in Greece. The antimicrobial resistance rates noted herein raise questions regarding the appropriateness of currently suggested antimicrobials in guidelines and imply that a revision could be required. Practicing clinicians should always be aware of local microbiological data that allow the selection of appropriate antimicrobials for the management of infections. Finally, the increasing rates of VRE noted herein mandate further actions from the point of infection control and antimicrobial stewardship.

Epidemiology and antimicrobial sensitivities of 536 multi-drug-resistant gram-negative bacilli isolated from patients treated on surgical wards

BACKGROUND

In this era of increasing antimicrobial resistance, infections caused by multi-drug-resistant (MDR) gram-negative bacilli (GNB) are becoming more common and pose a challenge to all clinicians, including surgeons.

METHODS

We evaluated the epidemiology and antimicrobial sensitivities of GNB isolated from patients treated on surgical wards at the University Hospital of Heraklion, Crete, Greece, from 2004 to 2009. The MDR isolates were defined according to an international expert proposal supported by the U.S. Centers for Disease Control and Prevention and the European Centre for Disease Prevention and Control.

RESULTS

A total of 1,153 GNB were isolated; 536 (46.5%) were MDR. The most common isolates were Escherichia coli (312 [27.8%]; MDR rate 50.2%), Pseudomonas aeruginosa (298 [25.8%]; MDR rate 39.6%), Acinetobacter baumannii (137 [11.9%]; MDR rate 83.9%), and Klebsiella pneumoniae (112 [9.7%]; MDR rate 44.6%). Most pathogens were isolated from patients hospitalized in the Departments of Surgical Oncology (32.3%), Orthopedic and Trauma Surgery (31.8%), General Surgery (18.1%), and Pediatric Surgery (15.5%). The clinical specimens comprised pus (45.1%), normally sterile fluids (22.5%), urine (16.8%), blood (6.3%), and other body fluids. Most effective in vitro against all MDR pathogens were colistin (83%), meropenem (57%), and imipenem-cilastatin (56%). The MDR P. aeruginosa was susceptible most often to colistin (94%) and aminoglycosides (tobramycin 56%, amikacin 55%), MDR A. baumannii only to colistin (94%), and MDR K. pneumoniae to meropenem (92%) and aminoglycosides (amikacin 76%, gentamicin 74%).

CONCLUSION

In a region with a high prevalence of antibiotic resistance, almost one-half of GNB isolated from surgical patients were MDR. Surgeons may consider these developments to guide empiric antibiotic therapy for infections caused by gram-negative pathogens.

Gentamicin collagen sponges for the prevention of sternal wound infection: a meta-analysis of randomized controlled trials

OBJECTIVE

The study objective was to determine whether the application of gentamicin collagen sponges reduces sternal wound infections in patients undergoing cardiac surgery.

METHODS

A meta-analysis of randomized controlled trials was performed.

RESULTS

Four randomized controlled trials were eligible for inclusion. By pooling data from 4 randomized controlled trials (4672 per-protocol patients), gentamicin collagen sponges reduced deep sternal wound infections (risk ratio, 0.62; 95% confidence interval, 0.39-0.97) and any sternal wound infections (risk ratio, 0.61; confidence interval, 0.39-0.98). In contrast, no benefit was demonstrated regarding superficial sternal wound infections (4 randomized controlled trials [4672 patients]; risk ratio, 0.65; 95% confidence interval, 0.34-1.25) and all-cause mortality (3 randomized controlled trials [3994 patients]; risk ratio, 0.90; 95% confidence interval, 0.57-1.42). On the basis of data from 2 randomized controlled trials (3410 patients), gentamicin collagen sponges also seemed to reduce surgically treated sternal wound infections (risk ratio, 0.59; 95% confidence interval, 0.41-0.86). The most commonly isolated pathogens were coagulase-negative Staphylococcus spp (43%) and Staphylococcus aureus (28%).

CONCLUSIONS

Gentamicin collagen sponges seem to reduce the sternal wound infection rate in patients undergoing cardiac surgery. The statistical heterogeneity among the existing trials underlines the need for additional large, high-quality randomized controlled trials.