Microbiological monitoring is one of the major elements of infection control. Results can be used by medical officers to study the etiological structure dynamics and antibiotic resistance profiles of various microorganisms. Further, the tactics and strategy of antibiotic prevention and treatment can be reviewed to identify hospital strains and the empirical antibacterial treatment prescribed for prophylaxis and therapy can be validated.
In the last decades, the negative effect of infections on human health has resulted not only from the emergence of “new” and the return of “old” infections but also from the development of resistance to antimicrobial medicines that has resulted in a rapid decline in the efficiency of causal treatment against infections. Though therapy failures resulting from resistance attract less public attention than the emergence of new infections, the urgency and relevance of this problem is fully recognised by medical specialists throughout the world . In 2001 the World Health Organisation (WHO) approved and published the Global Strategy for Containment of Antimicrobial Resistance . WHO and countries of the European Union and North America view the development and spread of antimicrobial resistance as a global problem and a national priority. In the USA the spread of antimicrobial resistance is regarded as a national security threat . There are national programmes aimed at preventing the spread of antimicrobial resistance. In February 2004 a meeting of the WHO experts, was held in Wernigerode, Germany. The meeting was devoted to the implementation of the Global Strategy for Containment of Antimicrobial Resistance and it was suggested to categorize antimicrobial resistance as a new infection. In all documents supplied the attention focused on the action plan targeted at the optimization of antibacterial usage and on the principles of the development and spread of antimicrobial resistance.
In 2005, the Centre of Shared Access (CSA) was established as part of the microbiological laboratory at the Municipal Centre for Hygiene and Epidemiology in Minsk. At present, the CSA provides the up-to-date laboratory diagnostics for 19 hospitals and 62 outpatient and polyclinic facilities in the city. The establishment of the centralised municipal database for microbiological investigations resulted in the development of microbiological monitoring, which is one of the main elements of the infection control system. Microbiological monitoring is currently practiced at all hospitals of Minsk.
This report provides an analysis of the microbiological monitoring data on blood tests for hemoculture that are the most reliable tests for diagnosing generalized and localized infections and complications. The data were collected in 2006 – 2008 from patients treated in 19 hospitals in Minsk.
The CSA is equipped with the most up-to-date facilities and consumables for cultivation of microorganisms under the most favourable conditions. In addition, high-performance automated technology for the identification of microorganisms and drug sensitivity is available. The CSA equipment and specialists’ qualifications allows performing up to 700,000 investigations per year and the identification of over 500 species of microorganisms. The data analysis is performed with the help of WHONET analytical software as recommended by WHO. Microorganisms in blood were identified with the help of the BacT/Alert 3D blood sterility analyser and the following microbiological analysers: ATB Expression, mini Api and VITEK 2 Compact. Antibiotic sensitivity for pathogens was estimated for more than 30 antibiotics by the disk diffusion method and use of the VITEK 2 Compact automated bacteriological analyser. We analysed resistance to the most relevant antibiotics (amoxicillin /clavulanate, ampicillin, oxacillin, cefazolin, ceftazidime, cefepime, erythromycin, ciprofloxacin, vancomycin, imipenem, meropenem, gentamicin, amikacin) with regard to the increasing antibiotic resistance.
During the reporting period, 17,676 blood samples were obtained from patients suffering from generalised and localised infections (pneumonia, sepsis, endometritis, pyelonephritis, mastitis, pancreatitis, apostem, phlegmon, osteomyelitis, etc.). Microorganisms were found in 2,819 (16%) samples. Over 90 various genera and species of microorganisms were identified and 52% of positive samples contained 5 prevailing agents (Figure1).
Figure 1. Microorganisms most frequently detected in blood samples, 2006 – 2008 (n=1466)
In 2006 – 2008 the percentage of resistant strains of Staphylococcus epidermidis was 97.9% to amoxicillin/clavulanate, 98% to oxacillin, 92.8% to cefazoline, 83% to erythromycin, 57% to ciprofloxacin and 1.3% to vancomycin. The proportion of resistant Staphylococcus aureus strains was 75.9 to amoxicillin/clavulanate, 75.3% to oxacillin, 60.4% to cefazoline, 60.6% to erythromycin, 58.4% to ciprofloxacin, and 0.7% to vancomycin. Resistant Acinetobacter baumannii strains were 55.9% to imipinem, 44.2% to meropenem, 44.2% to amikacin, 74% to cefepime, 91.8% to ceftazidime, and 92.5% to ciprofloxacin. The proportion of resistant Enterococcus faecium strains was 75% to amoxicillin/clavulanate, 95.1% to ampicillin, 97.9% to gentamycin, and 6% to vancomycin. A low resistance of Klebsiella pneumoniae ss. pneumonia to carbapenems was revealed; 0.6% to imipenem and 4.6% to meropenem. The percentage of strains resistant to amikacin was 69.7%, to ciprofloxacin 77.8%, to ceftazidime 90.9%, and to cefepime 91.2%.
In Minsk hospitals the gram-negative rods are still considered to be a serious problem. However, in recent years greater problems have been caused by antibiotic resistant gram-positive cocci with an increasing amount of staphylococci strains resistant to methicillin and fluorquinolones. Similar tendencies have been observed in Belarus and neighbouring countries. In accordance with the results of the REZORT investigation, the average proportion of the S.aureus strains resistant to methicillin in the intensive care units of Russian hospitals was 49.9% . This figure demonstrates the tendency as compared to 2000 – 2001 when the average resistance of such strains was 34% . The high occurrence of associated staphylococci resistance to antibiotics of other pharmacological groups including macrolides, tetracyclines, lincosamides, aminoglycosides, fluorquinolones, and chloramphenicol (with the resistance proportion ranging from 34.1% for moxifloxacin to 53.5% for chloramphenicol) has been revealed.
The results of microbiological monitoring of bacteriological agents and resistance to antimicrobials provides the basis for developing new strategies and reviewing the existing regional recommendations for conducting adequate empirical antibiotic therapy and for preventing the spread of multiresistant hospital strains of microorganisms.
- Сидоренко С.В., Эйдельштейн М.В. Механизмы резистентности микроорганизмов. Практическое руководство по антиинфекционой химиотерапии. Под ред. Страчунского Л.С., Белоусова Ю.Б., Козлова С.Н. М., 2007: 19-31.
- WHO Global Strategy for Containment of Antimicrobial Resistance. World Health Organization 2001. Available from: http://www.who.int/drugresistance/WHO_Global_Strategy_English.pdf
Russian version: http://www.who.int/drugresistance/WHO_Global_Strategy_Russian.pdf
- National Intelligence Council. The Global Infectious Disease Threat and Its Implications for the United States. 2000.
Available from: http://www.dni.gov/nic/PDF_GIF_otherprod/infectiousdisease/infectiousdiseases.pdf
- Dekhnich A., Ryabkova E., Kretchikova O., et al. Antimicrobial resistance of nosocomial strains of Staphylococcus aureus in Russian ICUs: Results of multicenter study. Presented at 46th Interscience Conference on Antimicrobial Agents and Chemotherapy (ICAAC 2006), September 27-30, 2006, San Francisco, CA, USA. Poste K-794.
- Страчунский Л.С., Дехнич А.В., Эдельштейн И.А. и соавт. Эпидемиология антибиотикорезистентности нозокомиальных штаммов Staphylococcus aureus в России: результаты многоцентрового исследования. Клин Микробиол Антимикроб Химиотер. 2002; 4: 325-36.