Establishment of an active laboratory-based surveillance for bacterial meningitis in Croatia and molecular characterization of Neisseria meningitidis isolates causing meningococcal disease that were collected in the year 2000, the first year of activity.

In 2000, 23 Neisseria meningitidis (meningococcal [Men]) isolates were collected in Croatia through an active laboratory-based surveillance for bacterial meningitis (17 Men serogroup B [MenB], 4 MenC, 1 MenW135, and 1 nongroupable isolate). Molecular characterization revealed a substantial level of diversity with only six isolates belonging to electrophoretic type 5 (ET-5) and ET-37 hypervirulent complexes.

Comparison of five different methods for detection of SHV extended-spectrum beta-lactamases.

Five different methods for detection of different types of SHV extended-spectrum beta-lactamases (ESBL) were compared: minimum inhibitory concentration (MIC) determination of beta-lactam with and without clavulanic acid, double-disk synergy test (DDST), inhibitor potentiated disk diffusion test (IPDDT), three-dimensional test (TDT) and PCR/Nhe I test. MIC determination of beta-lactam with and without clavulanic acid was the most sensitive method regardless of the type of beta-lactamase. However the specificity of this method was a little above 90%. IPDDT turned out to be a very sensitive method too but it lacks specificity because 26.9% of ceftazidime sensitive strains (putative ESBL negative), gave a positive result. It is important to put all four disks on the plate because ceftazidime and aztreonam were more sensitive indicators for SHV-5 and SHV-12 beta-lactamase producers while cefotaxime and ceftriaxone were more reliable in detecting SHV-2 beta-lactamase producers. The DDST detected all SHV-5 and SHV-12 beta-lactamase producers and 95.2% of SHV-2, so it was less sensitive than MIC determination but was highly specific, since there were no false negative results observed. The sensitivity of DDST can be improved by using all four disks and placing them at the smaller distance from the central disk (2.5 cm). The TDT was the least sensitive method, particularly for SHV-5 and SHV-12 beta-lactamase producers. The PCR/Nhe I test for detection of ESBL blaSHV genes is a highly sensitive and specific method but it is rather laborious and thus not very practical for use in routine clinical laboratories. Nevertheless it has potential to serve as the gold standard in epidemiological investigations on ESBLs. According to the results of this investigation MIC determination of beta-lactam with and without clavulanic acid, even if only one antibiotic is used and the PCR/Nhe I tests are the most reliable methods for detection of SHV ESBLs.

[Effect of inoculum size on sensitivity and specificity of the double-disk synergy test for the detection of wide-spectrum beta-lactamases]. / Utjecaj velicine inokuluma na osjetljivost i specificnost dvostrukog disk-sinergijskog testa u detekciji beta-laktamaza prosirenog spektra.

The plasmid-mediated extended-spectrum beta-lactamases (ESBL) confer resistance to oxymino-cephalosporins, such as cefotaxime, ceftazidime, and ceftriaxone and to monobactams such as aztreonam. It is well known fact that ESBL producing bacteria exhibit a pronounced inoculum effect against broad spectrum cephalosporins like ceftazidime, cefotaxime, ceftriaxone and cefoperazone. The aim of this investigation was to determine the effect of inoculum size on the sensitivity and specificity of double-disk synergy test (DDST) which is the test most frequently used for detection of ESBLs, in comparison with other two methods (determination of ceftazidime MIC with and without clavulanate and inhibitor potentiated disk-diffusion test) which are seldom used in clinical laboratories. The experiments were performed on a set of K. pneumoniae strains with previously characterized beta-lactamases which comprise: 10 SHV-5 beta-lactamase producing K. pneumoniae, 20 SHV-2 + 1 SHV 2a beta-lactamase producing K. pneumoniae, 7 SHV-12 beta-lactamase producing K. pneumoniae, 39 putative SHV ESBL producing K. pneumoniae and 26 K. pneumoniae isolates highly susceptible to ceftazidime according to Kirby-Bauer disk-diffusion method and thus considered to be ESBL negative. According to the results of this investigation, increase in inoculum size affected more significantly the sensitivity of DDST than of other two methods. The sensitivity of the DDST was lower when a higher inoculum size of 10(8) CFU/ml was applied, in distinction from other two methods (MIC determination and inhibitor potentiated disk-diffusion test) which retained high sensitivity regardless of the density of bacterial suspension. On the other hand, DDST displayed higher specificity compared to other two methods regardless of the inoculum size. This investigation found that DDST is a reliable method but it is important to standardize the inoculum size.

[Neisseria meningitidis with a decreased sensitivity to penicillin in the Zagreb District]. / Neisseria meningitidis smanjene osjetljivosti na penicilin na podrucju zagrebacke Zupanije.

Of the total of 35 clinical isolates from blood and/or cerebrospinal fluid in patients from the Zagreb area in the period from 1996-1999 Neisseria meningitidis serogroup B was identified in 33 (94%). N. meningitidis strains with decreased susceptibility to penicillin have been occurring in Zagreb since 1998, and during the two-year period in this study we isolated 3/19 (16%) such strains (MIC, 0.12 microgram/ml). Molecular typization of strains with decreased susceptibility to penicillin shows that they do not belong to a particular meningococcal clonal group. All isolated N. meningitidis strains were susceptible to the third generation cephalosphorins, quinolones and chloramphenicol. A single strain (3%) was resistant to rifampin, but 13/35 (37%) were resistant to trimethoprim/sulfamethoxazole. Consequently, trimethoprim/sulfamethoxazole is not recommended for chemoprophylaxis of meningococcal disease. Initially patients with meningococcal disease should be treated with the third generation cephalosporins, and further treatment should be continued in accordance with the antimicrobial susceptibility testing results. This study emphasizes the utility and importance of meningococcal disease monitoring throughout the Republic of Croatia.

Antibiotic resistance among gram-negative nosocomial pathogens in the intensive care unit: results of 6-year body-site monitoring.

Results of 6-year body-site monitoring in an intensive care unit (ICU) are presented and antimicrobial resistance of gram-negative isolates analyzed. The study included 622 patients. Six hundred thirty-five bacterial isolates-causes of nosocomial sepsis, pneumonia, and urinary tract infections (UTIs)-were tested during the study. Gram-negative bacteria were the predominant isolates, causing 65% of cases of sepsis, 78.7% of pneumonias, and 70.2% of UTIs. Gram-negative isolates (454) were highly resistant to antimicrobials commonly used in the ICU, with the exception of imipenem. Resistance was 1.1% among pathogens responsible for UTIs, 6.7% among those causing sepsis, and 13.6% among those responsible for pneumonia. Klebsiella pneumoniae associated with pneumonia and sepsis was significantly less resistant to ciprofloxacin than were isolates from urine (22.8% and 13.9%, respectively, vs 44.4%). Pseudomonas aeruginosa strains responsible for pneumonia were less resistant to ceftazidime than were isolates causing sepsis and UTI (35.7% vs 51.3% and 51.5%, respectively). Acinetobacter calcoaceticus strains associated with UTI were significantly more resistant to netilmicin than were strains responsible for sepsis and pneumonia (83.3% vs 40.3% and 42.6%, respectively). The study confirmed that in addition to focused microbiologic surveillance, multiple-body-site monitoring can provide unique information about the sensitivity of the pathogens involved. The results suggest that antimicrobial resistance among nosocomial pathogens depends on the site of infection or the type of microbiologic specimen.

[Analysis of the flow of medical information from Croatia into the world]. / Analiza tokova medicinskih informacija iz Hrvatske u svijet.

It is commonly thought that an article published in a renown international journal gives its authors better chances for visibility. The present paper aims at answering three questions: (a) does an article published in a top international journal guarantee that its authors will be visible, (b) is an article published in a domestic journal (not covered by ISI) completely inaccessible to the international public, and (c) which are the information flows and how far does the medical information from Croatia reach. Selected was a corpus of 60 authors, who simultaneously publish in foreign journals and in Lijecnicki vjesnik (LV). The corpus consists of 1053 articles published in the 1961-1986 period. Out of these, 369 articles were published in LV and 684 in foreign journals; 177 among them are covered by the Science Citation Index. A total of 4481 citations were collected for the entire corpus of 1053 articles. The citations pertain to 506 articles, i.e. 48% of articles were cited. There are 190 cited and 83 uncited journals. The citations were distributed among 890 journals. Although the studied authors published their papers in renown international journals, a number of examples proves that this does not guarantee their visibility. An article published in LV need not necessarily remain inaccessible to the world--this depends on the article itself. The present analysis provides a compendious insight into the transfer of information from Croatia into the world. The data from citation analysis enable the deduction of "average number of citations per paper". With an appropriate interpretation it can be used as an indicator of information transfer.

[Is the medical research carried out in Croatia an integral part of science worldwide?]. / Jesu li medicinska istrazivanja izvedena u SR Hrvatskoj integralni dio znanosti u svijetu?

Presented are the results of a scientometric study carried out on a sample containing 5339 journal articles published by the Croatian authors over the period of 11 years. The analysis is performed on a macro-level, i.e. it is based on journal-aggregates data. To evaluate whether Croatian output in medicine is incorporated into the mainstream of the world science or suffers from the intellectual island effect, the extent of the journals' coverage by high quality international secondary literature, is examined. The extent of coverage is found to be 80%, making only that part of the Croatian output accessible to the world scientific community.