Antibiotic bacterial resistance is an important public health problem. Antibiotic inappropriate use is critical to development of bacterial resistance. Nephrology Departments meet several sites of microbiological interest: Urinary Tract, Central Venous Catheter (CVC) for hemodialysis treatment, Peritoneal Catheter (PC) for peritoneal dialysis (PD) treatment, the peritoneal dialysis fluid, the bloodstream, the CVC- or PD- skin exit-sites. Knowledge both of the pathogens epidemiology and the antibiotic resistance is necessary for timely and effective treatment of infections.We aimed to study the prevalence of bacterial pathogens and their emerging resistance patterns to commonly used antibiotic drugs.
Material and methods
We performed a retrospective analysis of microbiological reports from patients admitted to Nephrology Department between January 2008 and December 2012. The infection sites were: urine, soft tissues, peritoneal dialysis fluid, bloodstream, CVC- or PD- skin exit-site, CVC- or PC-tips. We used commercial blood culture bottles to assess bacteraemia and sterile cotton for superficial infections; the urine samples and CVC- or PC- tips were collected in sterile single-use pots for microbiological culture. All samples were collected and processed from patients in accordance with standard protocols. Antibiotic susceptibility of the isolates was done by disc diffusion method according to international guidelines recommendations.
We analyzed 1249 microbiological reports. The majority of isolates were: Escherichia coli, Staphylococcus Aureus, Enterococcus Faecalis, Pseudomonas Aeruginosa, Candida, Staphylococcus Epidermidis, Klebsiella Pneumoniae. We reviewed the antibiotic susceptibility patterns for the firsts 4 bacterial pathogens identified. We found: a) Escherichia Coli: the susceptibility to imipenem, meropenem, colistin, ertapenem and tigecycline was 100%; to amikacin was 97.7%; the susceptibility to piperacillin-tazobactam, gentamicin, cefotaxime, ceftazidime, tobramycin, cotrimoxazole, piperacillin, ciprofloxacin, levofloxacin, ampicillin was under 90%. The proportion of extended spectrum betalactamase (ESBL)-Escherichia Coli was 37%. b) Staphylococcus Aureus: the susceptibility to linezolid, mupirocin and tigecycline was 100%; to teicoplanin and vancomycin, fusidic acid, daptomycin, trimethoprim/sulfamethoxazol, tobramycin and tetracycline was over 90%. The proportion of methicillin resistant Staphilococcus Aureus (MRSA) was 15% c) Enterococcus Faecalis: the susceptibility to teicoplanin, daptomycin was 100%; to amoxicillin and clavulanic acid, vancomycin, ampicillin-sulbactam, imipenem and linezolid was over 90%. d) Pseudomonas Aeruginosa: the susceptibility to colistin was 100; to imipenem was 78%; to meropenem and piperacillin was 77%; to amikacin was 75%.(Figure)
Nephropathic patients are at risk for infections caused by nosocomial multidrug resistant (MDR) pathogens exhibiting decreased susceptibility to many antibiotic drugs. Antimicrobial regimens can be modified when the infecting strain has been identified and antimicrobial susceptibilities are known. The nephrological practice meets multiple pathologies of microbiological interest: post-infectious GN, complicated Urinary Tract Infections (UTI), acute pyelonephritis, CVC-related infections, PD-related peritonitis, CVC- or PD-catheter skin exit-site infections, bloodstream infection (sepsis, bacteraemia). The prevalence of MDR bacterial pathogens, e.g. MRSA, ESBL-producing Enterobacteriaceae or vancomycin-resistant enterococcus (VRE), is increasing. In this study, Escherichia coli, Staphylococcus Aureus and Enterococcus Faecalis showed different antibiotic susceptibility patterns. Pseudomonas Aeruginosa showed high percentage of susceptibility to colistin only. Both Gram-positive and Gram-negative were resistant to fluoroquinolones. Based on our survey, in suspected UTI and/or pyelonephritis we prescribe as empiric therapy (ET): amikacin, amoxicillin and clavulanic. In suspected CVC infection we prescribe as ET: trimethoprim/sulfamethoxazole and amikacin. It should not be used fluoroquinolones in UTI as ET because the susceptibility is less than 55%. Penicillin G should not be used as ET because its lowest susceptibility.
Infections caused by MDR organisms are becoming more frequently in daily practice. Antibiotic resistance of bacterial pathogens to commonly used antibiotics is increasing and it is important to review the recommended guidelines for ET in line with local patterns of bacterial pathogens and antibiotic susceptibilities. Depending on antibiotic susceptibility pattern of the isolates, antibiotic ET should be updated. Our report on bacterial spectra of major antibiotic susceptibility patterns enables a more rational use of antibiotics.