[Monitoring bacterial resistance to antibiotics in the CroatianRepublic]. / Pracenje rezistencije bakterija na antibiotike u Republici Hrvatskoj.

In 1996 a Committee for antibiotic resistance surveillance in Croatia was founded by the Croatian Academy of Medical Sciences. In this study antibiotic surveillance results for the period June 1-December 31, 1997 from 12 microbiology laboratories throughout Croatia are presented. Sensitivity to antibiotics was determined by disk diffusion method for the following bacteria: Streptococcus pneumoniae, Staphylococcus aureus, Enterococcus spp., Escherichia coli, Klebsiella spp. and Pseudomonas aeruginosa. In general, high proportion of resistant isolates was recorded throughout Croatia, although some regional variations were noticed. Mean resistance of pneumococci to penicillin was 38%, in S. aureus resistance to methicillin was 47%, and 3rd generation cephalosporin-resistance in E. coli was 6% and in Klebsiella spp. 21%. In P. aeruginosa resistance to gentamicin averaged 50%, to imipenem 13% and to ceftazidim 8%. Future aims of the Committee are to continue routine antibiotic resistance surveillance during certain periods every year, and to estimate clinical significance of resistant bacteria, detect mechanisms of resistance and improve the quality of laboratory work through education and quality control projects.

Epidemiological analysis of methicillin-resistant Staphylococcus aureus in a Zagreb Trauma Hospital using a randomly amplified polymorphic DNA-typing method.

During a 1-month period in 1996, all inpatients and staff in the Zagreb Trauma Hospital were screened for methicillin-resistant Staphylococcus aureus (MRSA) carriage in order to control MRSA spread within the hospital. During the study period, 663 patients were admitted to the hospital, and screening prior to discharge revealed that 42 were colonised or infected with MRSA. Twenty-three (55%) of these would not have been detected if active screening had not been performed. Amongst 205 staff members, MRSA carriage was only found in one (0.5%) nurse. The prevalence and incidence of MRSA carriage varied significantly amongst the wards and was related to the length of hospital stay. One-third of the patients colonised or infected with MRSA had a history of previous admission to another hospital, and one-third were transferred to another institution after discharge. Thirty-nine of 42 MRSA isolates shared the same antibiotic sensitivity pattern, suggesting endemic spread of MRSA. However, randomly amplified polymorphic DNA molecular typing revealed four profiles, the most common involving 15 of 36 tested strains. There was no obvious clustering of epidemiological types by ward, except for the appearance of a single type on the burns unit, and it was likely that different strains had been introduced into the hospital by patient transfers from elsewhere. The results of this study indicate that a substantial proportion of MRSA carriers escape infection control measures if active screening is not performed. Based on the results of this study, steps have been taken to improve interhospital communication about the transfer of patients colonised with MRSA. Randomly amplified polymorphic DNA typing proved to be a useful aid to epidemiological investigations of MRSA.

Prevalence and antibiotic sensitivity pattern variations of bacterial isolates in different settings and different periods of time.

The problem of bacterial antibiotic resistance emerged as soon as the first antibiotics became available for clinical use. The aim of this study was to estimate differences in the prevalence and antibiotic sensitivity pattern of the most frequent isolates between two different hospitals (Sveti Duh General Hospital, Zagreb, und University Hospital of Traumatology, Zagreb), different wards of the same hospital (nephrology, urology and surgery of Sveti Duh General Hospital) and different periods of time (01. 03.--31. 12. 1993 and 01. 01.--31.07. 1995). E. coli was the most frequent urine isolate at the Sveti Duh Hospital, whereas more resistant K. pneumoniae was the most frequent urine isolate at the University Hospital of Traumatology. S. pneumoniae was the most frequent lower respiratory tract isolate in the Sveti Duh Hospital, whereas in the University Hospital of Traumatology P. aeruginosa and A. anitratus prevailed. In both hospitals, staphylococci were the most frequent blood culture isolates, but in gram-negative sepsis E. coli was the most frequent pathogen in the Sveti Duh Hospital, and S. marcescens in the University Hospital of Traumatology. Difference in the prevalence of microorganisms may have partially been due to the different patient profile in the two hospitals, but we showed that the antibiotic sensitivity pattern of the most frequent nosocomial pathogens P. aeruginosa and K. pneumoniae differed between different settings as well, and that this pattern may change with time. This clearly points to the need of continuous surveillance of the prevalence and antibiotic sensitivity pattern of microorganisms in local environment, which should be the basis for effective empiric therapy.

Diagnostic value of a P-fimbriation test in determining duration of therapy in children with urinary tract infections.

The patients were 117 children (aged 4 months to 14 years) with uncomplicated urinary tract infections caused by co-trimoxazole-sensitive Escherichia coli. The patients were randomly assigned to receive treatment with co-trimoxazole for 3 days (n = 58) or 7 days (n = 59). Urine was analyzed for bacteria before and immediately after treatment and again at 1 and 2 months. After 3 days' treatment, infection persisted in 14 of 31 patients with P-fimbriated strains of E coli and in 1 of 27 patients with non-P-fimbriated strains. After 7 days' treatment, infection persisted in 2 of 40 patients with fimbriated strains and in none of the 19 patients with nonfimbriated strains. One or 2 months after treatment, 3 days' treatment was rated successful in 26 of 27 patients with nonfimbriated strains and in none of the patients with fimbriated strains. Seven days' treatment was rated successful in all patients with nonfimbriated strains and in 32 of 40 patients with fimbriated strains. The results indicate that the length of treatment of urinary tract infections in children should be adjusted according to the presence of bacterial P-fimbriae in addition to the patients' clinical condition.

Disk diffusion sensitivity testing and antibacterial activity of azithromycin.

Azithromycin (CAS 83905-01-5) disks with the selected loading (10, 15, 20 micrograms) were used for determination of the most suitable azithromycin disk concentration. Estimation was carried out by means of the regression line related to the zone size inhibition. Testing was performed on a variety of freshly isolated gram-positive, gram-negative and anaerobic bacteria derived from various specimens collected from patients. Using the disk diffusion method with 10 micrograms of azithromycin per disk in total 431 gram-positive, 875 gram-negative bacterial strains and 59 anaerobic bacteria were analysed. It was concluded that azithromycin disk containing 10 micrograms is sufficient for determination of bacterial sensitivity.

An evaluation of netilmicin, 150 mg BID, in systemic infections.

The efficacy and tolerance of netilmicin administered in a simplified dosage schedule (150 mg BID) were evaluated in an open study of 20 patients with acute systemic infections. Duration of therapy ranged from 6 to 11 days. All isolated causative organisms were eradicated; 85% (17/20) of the patients experienced complete clinical resolution, and the remaining 15% (3/20) experienced definite improvement. No patients developed nephrotoxicity of ototoxicity. The results of this study demonstrate that netilmicin is both effective in the treatment of serious systemic infections and well tolerated when administered at 150 mg twice daily.