First Report of NDM-1-Producing Acinetobacter guillouiae.

BACKGROUND: Acinetobacter spp. is an opportunistic pathogen that has demonstrated increasing relevance in nosocomial infections. Carbapenem-resistant strains have been reported worldwide. METHODS: Since 2014, screening for metallo-ß-lactamases (MBLs) in all Acinetobacter spp. isolates using phenotypic methods and PCR has been implemented at the University Hospital Center Zagreb. RESULTS: The bacterial strain was isolated from the drain of a child hospitalized in a paediatric intensive care unit and identified as Acinetobacter guillouiae using a MALDI TOF automated system. The strain was resistant to meropenem, ceftazidime, cefotaxime, ceftriaxone, cefepime, sulbactam/ampicillin, gentamicin and ciprofloxacin, intermediately susceptible to piperacillin/tazobactam and imipenem, and susceptible to amikacin and colistin. The Hodge test and combined disk test with EDTA were positive. The MICs of meropenem and imipenem were not reduced by cloxacillin, but a small reduction of two dilutions was observed following the addition of sodium chloride, which indicated that OXA-58 was produced. PCR and sequencing of chromosomal DNA from boiled colonies revealed blaOXA-58 and blaNDM-1 genes. CONCLUSION: This is the first report of NDM-1 in Acinetobacter spp. in Croatia. The early detection of these genes will aid in the prevention and in the achievement of adequate infection control by limiting the spread of these organisms.

[Croatian guidelines for diagnostics and treatments of Helicobacter pylori infection]. / Hrvatski postupnik za dijagnostiku i terapiju infekcije Helicobacterom pylori.

In the past 30-year period of investigations, the crucial role of Helicobacter pylori in chronic gastritis, gastric and duodenal ulcer development, and subsequently in gastric cancer and MALT lymphoma pathogenesis, has been recognized. During the first meeting of European Helicobacter Study Group in 1996 in Maastricht, the first recommendations for diagnostics and treatments of Helicobacter pylori infection were published, later reviewed in 2000, 2007 and 2010. The first meeting of Croatian doctors focusing on the same topics, but suitable to specific national circumstances, was held as early as 1998. The need for updating the old guidelines has emerged during the last years. The working expert group of gastroenterologists was formed and gathered on Consesus Conference in December 2012 in Zagreb, to arrive to current guidelines for the clinical management of Helicobacter pylori infection in Croatia. The following topics relating to Helicobacter pylori infection were examined: 1. indications and contraindications for diagnostics and treatments; 2. diagnostic methods and 3. treatments applicable in our country.

Virulence Factors and Susceptibility to Ciprofloxacin, Vancomycin, Triclosan, and Chlorhexidine among Enterococci from Clinical Specimens, Food, and Wastewater.

Enterococcus faecalis and E. faecium are opportunistic pathogens commonly found in the microbiota of humans and other animals as well as in the environment. This article presents the results of antimicrobial susceptibility testing using phenotypic methods (broth microdilution and standardized disk diffusion) on selected clinical, food, and wastewater isolates of E. faecalis and E. faecium. The isolates were divided into subgroups based on their sensitivity to the following antibiotics: vancomycin (VAN) and ciprofloxacin (CIP), and biocides triclosan (TCL) and chlorhexidine (CHX). The study also investigated in vitro virulence factors, including biofilm formation ability, cell surface hydrophobicity (CSH) and ß-hemolysis, to explore aspects of pathogenesis. In our study, regardless of the isolation source, VAN-resistant (VAN-R) and CIP-resistant (CIP-R) E. faecalis and E. faecium were detected. The highest proportion of CIP-R strains was found among clinical isolates of E. faecalis and E. faecium, with clinical E. faecium also showing the highest proportion of VAN-R strains. But the highest proportion of VAN-R E. faecalis strains was found in wastewater samples. The highest TCL MIC90 values for E. faecalis were found in wastewater isolates, while for E. faecium, the highest TCL MIC90 values were observed in food isolates. The highest CHX MIC90 values for both E. faecalis and E. faecium were identified in clinical specimens. The results obtained for E. faecalis did not indicate differences in TCL MIC and CHX MIC values with respect to sensitivity to VAN and CIP. Higher CHX MIC50 and CHX MIC90 values were obtained for CIP-R and VAN-R E. faecium. Among the tested isolates, 97.75% of the E. faecalis isolates produced biofilm, while 72.22% of the E. faecium isolates did so as well. In biofilm-forming strength categories III and IV, statistically significantly higher proportions of CIP-susceptible (CIP-S) and VAN-susceptible (VAN-S) E. faecalis were determined. In category III, there is no statistically significant difference in E. faecium CIP sensitivity. In category IV, we had a significantly higher proportion of CIP-R strains. On the other hand, the association between the moderate or strong category of biofilm formation and E. faecium VAN susceptibility was not significant. E. faecalis isolated from wastewater had a CSH index (HI) ≥ 50%, categorizing them as "moderate", while all the other strains were categorized as "low" based on the CSH index. Among the E. faecalis isolates, cell surface hydrophobicity indices differed significantly across isolation sources. In contrast, E. faecium isolates showed similar hydrophobicity indices across isolation sources, with no significant difference found. Moreover, no correlation was found between the enterococcal cell surface hydrophobicity and biofilm formation in vitro. After anaerobic incubation, ß-hemolytic activity was confirmed in 19.10% of the E. faecalis and 3.33% of the E. faecium strains.

Infrequent finding of metallo-ß-lactamase VIM-2 in carbapenem-resistant Pseudomonas aeruginosa strains from Croatia.

One hundred sixty-nine nonreplicate imipenem-resistant Pseudomonas aeruginosa strains isolated in a large hospital on the coastal region of Croatia were studied. The most active antibiotics were colistin and amikacin. Most of the isolates were multiresistant. The most prevalent serotype was O12, followed by O11. Six strains carried the bla(VIM-2) gene located in a novel class 1 integron composed in its variable part of the bla(VIM-2)-bla(oxa-10)-ΔqacF-aacA4 genes. Metallo-ß-lactamase-producing strains belonged to sequence types ST235 and ST111.

Value of rapid aetiological diagnosis in optimization of antimicrobial treatment in bacterial community acquired pneumonia.

In 80 adult patients with community acquired pneumonia (CAP) conventional microbiological methods, polymerase chain reaction (PCR) and serum C-reactive protein (CRP) levels were performed and the appropriateness of the empirical antimicrobial treatment was evaluated according to bacterial pathogen detected. The aetiology was determined in 42 (52.5%) patients, with Streptococcus pneumoniae as the most common pathogen. PCR applied to bronchoalveolar lavage (BAL) provided 2 and PCR on sputum samples 1 additional aetiological diagnosis of CAP The mean CRP values in the S. pneumoniae group were not significantly higher than in the group with other aetiological diagnoses (166.89 mg/L vs. 160.11 mg/L, p = 0.457). In 23.8% (10/42) of patients with determined aetiology, the empirical antimicrobial treatment was inappropriate. PCR tests need further investigation, particularly those for the atypical pathogens, as they are predominant in inappropriately treated patients. Our results do not support the use of CRP as a rapid test to guide the antimicrobial treatment in patients with CAP.

[Comparative urinary bactericidal activity of oral antibiotics against gram-positive pathogens]. / Usporedna urinarna baktericidna aktivnost oralnih antibiotika prema gram-pozitivnim urinarnim patogenima.

In routine bacteriological laboratories the antibacterial activity of antibiotics is determined by in vitro testing, usually by disk-diffusion test. However, in vitro testing does not always reflect antibacterial efficiency of antibiotics in vivo. In this investigation, the urine samples obtained in a single oral dose pharmacokinetic study were examined for their bactericidal activity against a range of relevant Gram-positive urinary tract pathogens. Urinary bactericidal activity of linezolid had been previously compared with ciprofloxacin but not with other oral antibiotics such as beta-lactams. Linezolid showed satisfactory urinary bactericidal titres throughout the whole testing period against all Gram-positive cocci. Fluoroquinolones displayed high and persisting levels of urinary bactericidal activity against staphylococci, but their activity against enterococci was weaker. According to the results of ex-vivo testing amoxycillin could be recommended only for infections caused by E. faecalis. Amoxycillin combined with clavulanic acid can be considered as a therapeutic option for infections caused by S. saprophyticus and E. faecalis. Older cephalosporins had high titres only against S. saprophyticus. Their drawback is a short elimination half-time in urine resulting in rapid decrease of urinary bactericidal titers during dosing interval. Furthermore, they do not show activity against enterococci due to their intrinsic resistance to cephalosporins.

The effectiveness of systemic eradication therapy against oral Helicobacter pylori.

BACKGROUND: Helicobacter pylori infection is associated with numerous gastroduodenal diseases. The oral cavity could be a potential extragastric reservoir for H. pylori, and oral H. pylori might cause gastric reinfection after the eradication therapy. The aim of the study was to evaluate the presence of H. pylori in oral cavity of patients with gastric H. pylori infection and to examine the effectiveness of the eradication therapy against H. pylori in stomach and in the oral cavity. METHODS: Fifty-six patients with chronic periodontitis and gastric H. pylori were enrolled in the study. Gastric H. pylori infection was determined using (13) C-urea breath test before and 3 months after eradication therapy. The presence of the oral H. pylori was assessed using polymerase chain reaction before and 3 months after eradication therapy. The 1-week eradication therapy consisted of amoxycilin 1 g, clarithromycin 500 mg, and proton pump inhibitor 20 mg twice a day. RESULTS: Of 56 subjects with gastric infection, 23 (41.1%) harbored H. pylori in the oral cavity. Eradication rate in stomach was 78.3%, whereas in the oral cavity, H. pylori was not detected from any sample after the eradication therapy. CONCLUSION: Almost half of the patients with gastric H. pylori harbored the bacterium in the oral cavity. After the eradication therapy, H. pylori was not detected in the oral cavity, what suggests high effectiveness of the therapy protocol in the oral cavity, or it is possible that oral H. pylori is of a transient character.

Effect of azithromycin on acute inflammatory lesions and colonic bacterial load in a murine model of experimental colitis.

BACKGROUND: The aim of this study was to investigate the effect of the macrolide antibiotic azithromycin on mucosal changes and colonic bacterial load in a murine model of colitis. METHODS: Colitis was induced in CD1 mice using enema of 0.2% solution of dinitrofluorobenzene, combined with skin sensitization. Four experimental groups of animals (N = 10 per group) were treated with 50 mg/kg/day azithromycin (AZ) or metronidazole (MN) perorally, starting 24 h before (AZ-1, MN-1) or 6 h after (AZ+1, MN+1) induction of colitis and for consecutive 5 days. Additional experimental mice group was treated with 10 mg/kg/day methylprednisolone intraperitoneally after induction of experimental colitis in the same manner (MP). Two control groups consisted of healthy animals (C) that received the challenge enema with phosphate-buffered saline (PBS) and animals with experimental colitis (chall) treated with equivolume of PBS perorally. Clinical score (0-5) and histopathologic score (0-30) were used to assess inflammatory changes, and colon washings were used to determine changes in bacterial load. RESULTS: The anti-inflammatory effect of azithromycin did not differ from the effect of methylprednisolone, when compared with control group with experimental colitis. Metronidazole did not show a significant anti-inflammatory effect. Number of colonic bacteria did not differ significantly between control and experimental groups of animals. CONCLUSIONS: We documented the anti-inflammatory effect of azithromycin in a murine model of acute colitis, suggesting that effects were targeted to oxidative burst and on mucosal/bacterial interface, independent of luminal bacterial load. Further studies should be focused on effect of azithromycin on the role of bacterial biofilm in perpetuation of chronic intestinal inflammation.

Molecular variants of human papilloma viruses type 16 and 6 in women with different cytological results detected by RFLP analysis.

HPV infections are common and the presence of the same high-risk type in cervical specimens can be due to reinfection or persistence. Persistent infection is the most important predictor for development of cervical carcinoma. The aim of this study was to validate PCR-RFLP with two sets of primers: MY09/MY11 that amplify a fragment of L1 and P1/P2 that amplify a fragment of E1 ORF. PCR product of MY09/MY11 was digested with a set of 6 restriction enzymes (RE) and PCR product of P1/P2 with a set of 12 RE. Cervical samples from 110 women patients of the University Gynecologic Clinic CHC Zagreb were analyzed. There were 98 (89.1%) PCR positive samples detected with P1/P2 primers, and 94 (85.5%) PCR positive samples detected with MY09/MY11 primers. Seven HPV types were detected with P1/P2-RFLP technique and 17 with MY09/MY11-RFLP PCR positive samples amplified with both primer pairs agreed with each other in 82 samples; 16 samples were only positive with P1/P2 and 12 samples were only positive by MY09/MY11. HPV 16 was detected in 39 samples with MY09/11-RFLP, out of these two variants (two different patterns) were found with P1/P2 using Dde I, Hae III and Eco I. HPV 6 was detected in 9 samples with MY09/11-RFLP, out of these two variants were found with P1/P2 using HinfI. Combining these two PCR-RFLP methods subtypes of HPV 16 and HPV 6 were detected.

Helicobacter pylori eradication therapy success regarding different treatment period based on clarithromycin or metronidazole triple-therapy regimens.

BACKGROUND: The study compares the eradication success of standard first-line triple therapies of different durations (7, 10, and 14 days). MATERIALS AND METHODS: A total of 592 naive Helicobacter pylori-positive patients were randomized to receive pantoprazole, amoxicillin, and clarithromycin or metronidazole for 14 days (PACl14 or PAM14), 10 days (PACl10 or PAM10), or 7 days (PACl7 or PAM7). H. pylori eradication was assessed by histological, microbiological, and rapid urease examination. RESULTS: The intention-to-treat (ITT) and per-protocol (PP) analyses have shown no overall statistically significant differences between the eradication success of PACl and PAM treatment groups (ITT p = .308, PP p = .167). Longer treatment duration has yielded statistically significant increase in eradication success for clarithromycin (ITT p = .004; PP p = .004) and metronidazole (ITT p = .010; PP p = .034) based regimens. Namely, PACl10, PACl14, and PAM14 protocols resulted in eradication success exceeding 80% in ITT and 90% in PP analysis. Primary resistance to clarithromycin and metronidazole equals 8.2% and 32.9%, respectively. Prolonging the metronidazole-based treatment duration in patients with resistant strains resulted in statistically significant higher eradication success. CONCLUSIONS: For all antimicrobial combinations, 14 days protocols have led to a significant increase of H. pylori eradication success when compared to 10 and 7 days, respectively. Prolonging the treatment duration can overcome the negative effect of metronidazole resistance. Only PAM14, PACl10 protocols achieved ITT success > 80% and should be recommended as the first line eradication treatment in Croatia.

Antimicrobial effect of 0.2% chlorhexidine in infected root canals.

The aim of this study was to identify bacteria from the infected root canals of teeth with chronic apical periodontitis, and to evaluate the antibacterial effect of 0.2% chlorhexidine (CHX), as an irrigant, in reducing the microbial flora 48h after root canal preparation. A total of 44 subjects were randomly divided in the experimental group and the control group. The first bacterial samples from all root canals were obtained in the beginning, before any treatment. During mechanical instrumentation, root canals were irrigated three times, with 0.2% CHX in the experimental group, and with saline solution in the control group. All canals were dried and temporarily sealed with zinc oxide-sulfate cement. After 48 h the second samples were obtained. Bacterial samples were subjected to microbiologic processing. The study indicates that 0.2% CHX is significantly effective in reducing the microbial flora, and could be used as an irrigant solution.

Emergence of uropathogenic extended-spectrum beta lactamases-producing Escherichia coli strains in the community.

The aim of this study was to determine the virulence characteristics and resistance pattern of the extended-spectrum/lactamases (ESBLs)-producing Escherichia coli strains isolated from urine of outpatients in the Zagreb region during a five-month period, and to compare them with the non ESBLs-producing E. coli strains isolated in the same period. Out of 2451 E. coli strains isolated from urine of nonhospitalized patients with significant bacteriuria, a total of 39 ESBLs-producing strains (1.59%) were detected by a double-disk diffusion technique and by the broth-dilution minimal inhibitory concentration reduction method. The 45 non ESBLs-producing strains were randomly chosen, and phenotype of the two groups of strains was characterized and compared. Serogroup O4, hemolysin production, expression of P- and type 1 fimbriae as well as resistance to gentamicin and amikacin were significantly more prevalent characteristics among the ESBLs-producing strains than among non ESBLs-producing strains (p < 0.01), while higher prevalence of trimethoprim-sulfamethoxazole resistance among ESBLs-producing strains was not statistically significant (p > 0.05). Chromosomal DNA analysis by pulsed-field gel electrophoresis exhibited a great genomic similarity among ESBLs-producing strains and revealed that those highly virulent and resistant E. coli strains isolated from urine of outpatients in the Zagreb region had a clonal propagation.

Antimicrobial susceptibility and the in vitro postantibiotic effects of vancomycin and ciprofloxacin against Bacillus cereus isolates.

BACKGROUND: Vancomycin and ciprofloxacin were often used in the therapy of infections associated with Bacillus cereus. METHODS: Four B. cereus food and clinical isolates were chosen for determination of time-kill curves and postantibiotic effects (PAE) of ciprofloxacin and vancomycin. RESULTS: According to the minimum inhibition concentration (MIC), breakpoints defined by CLSI for Staphylococcus spp. were all four strains intermediate for vancomycin (MIC = 4 µg/ml) and sensitive to ciprofloxacin (MIC = 0.2 µg/ml) except the strain Bc63 resistant to the last antimicrobial (MIC = 1.6 µg/ml). The lowest CFU values of tested strains were reached after 3-5 hours of exposure to 4 × MIC of vancomycin, and after 6-7 hours exposure to 10 × MIC of ciprofloxacin. The maximum reduction of the CFU in the presence of vancomycin and ciprofloxacin was about 2.46 log10 and 2.48 log10, respectively. The average duration of the PAE of vancomycin and ciprofloxacin was 0.94 and 1.60 hours, respectively. The statistically significant differences between PAEs induced with 3 × MIC, 4 × MIC and 8 × MIC of vancomycin were observed (P < 0.05). Both antibiotics did not affect the sporulation of tested bacterial strains. CONCLUSIONS: The differences in PAE duration were strain and antimicrobial dependent.

Lactate dehydrogenase activity in Bacteroides fragilis group strains with induced resistance to metronidazole.

The aims of this study were to induce in vitro metronidazole resistance in nim-negative Bacteroides fragilis group strains and to determine the lactate dehydrogenase (LDH) activity of the induced strains. A collection of B. fragilis group strains were identified by matrix-assisted laser desorption/ionisation time-of-flight mass spectrometry (MALDI-TOF/MS). Minimum inhibitory concentrations (MICs) for metronidazole were determined by the agar dilution technique. The presence of nim genes was screened by PCR. A sample of 52 nim-negative metronidazole-susceptible strains were selected at random and were exposed to metronidazole in the resistance induction experiment. LDH activity was measured by spectrophotometry. Of the 52 selected strains, 12 (23.1%) acquired resistance to metronidazole. MICs ranged from 8mg/L to 96mg/L. Eight of the twelve induced strains displayed decreased LDH activity, whilst only one expressed a significant increase in LDH activity with LDH values of 49.1U/mg and 222.0U/mg, respectively. In conclusion, in vitro induction of metronidazole resistance could be selected in nim-negative B. fragilis group strains. A statistically significant decrease in LDH activity was in contrast to previous findings in which, underlying higher metronidazole MICs, an increase in LDH activity compensated for the decreased activity of pyruvate-ferredoxin oxidoreductase (PFOR). These findings could be explained if the induction caused only physiological and not genetic changes. We believe that genetic mutations in the B. fragilis strain that demonstrated an emergent increase in LDH activity were responsible for the increased activity.

Antimicrobial efficacy of photodynamic therapy, Nd:YAG laser and QMiX solution against Enterococcus faecalis biofilm.

BACKGROUND: Lasers have been recommended in final root canal disinfection protocol, however, there is no clear evidence about their efficacy against bacteria in biofilms. The aim of the study was to evaluate and compare the disinfection effect of antimicrobial photodynamic therapy (aPDT), Nd:YAG laser and QMiX solution against Enterococcus faecalis biofilm. METHODS: The study sample consisted of 65 dentine slices, which were inoculated with E. faecalis and incubated anaerobically for three weeks. The dentine discs were randomly allocated to one of the following experimental groups: aPDT (100 mW, 10 mg/ml phenothiazinium chloride, 1 min), Nd:YAG laser (2 W, 15 Hz, 4×5 s), QMiX solution (1 min). Positive controls did not receive any treatment and negative controls were treated with 5.25% NaOCl. To harvest surviving adherent cells, each dentine sample was transffered to a test tube containing of TSB, serial ten-fold dilutions were made and aliquot of 1 ml was plated onto blood agar plates and incubated for 48 h. Colony forming units grown were counted and transformed into actual counts based on the dilution factor. The remaining viable cells after each protocol were analysed by FISH. RESULTS: The aPDT and the QMiX solution were equally effective, with the reduction rate of E. faecalis CFUs of 98.8% and 99.3% respectively (p=1.107). The Nd:YAG laser caused 96% reduction of E. faecalis (P<0.001). CONCLUSION: The aPDT and the QMiX solution showed similar antibacterial efficacy against old E. faecalis biofilm, followed by Nd:YAG irradiation.

KPC-Producing Klebsiella pneumoniae Isolates in Croatia: A Nationwide Survey.

BACKGROUND: In the last few years, Klebsiella pneumoniae strains producing K. pneumoniae carbapenemase (KPC) enzymes have emerged as important multidrug-resistant pathogens in hospitalized patients. This report describes KPC-producing isolates collected through the Croatian antimicrobial resistance surveillance program in the early stage of their dissemination in Croatia. MATERIALS AND METHODS: Forty-eight KPC-producing K. pneumoniae isolates, collected during a period from February 2011 to August 2013, were analyzed in this study. Antimicrobial susceptibility profiles were determined using disk diffusion and E-test. Pulsed-field gel electrophoresis (PFGE) and multilocus sequence typing (MLST) were used for epidemiological analysis. Identification of ß-lactamase genes and associated antibiotic resistance mechanisms was performed by polymerase chain reaction and positive products were sequenced. Localization of blaKPC was investigated by S1 PFGE and Southern hybridization. RESULTS: Of 40 participating centers in Croatia, KPC isolates were recorded in 9 of them. They all had multidrug-resistant phenotype, but showed varying levels of resistance to carbapenems. All isolates displayed ST258, and PFGE showed that all but one were closely related. All isolates harbored blaKPC-2. Isolate with a unique PFGE pattern produced TEM-1, while others produced TEM-116. All isolates harbored blaSHV-11, but were negative for blaCTX-M and blaAmpC genes. All isolates contain one KPC-harboring plasmid, ranging in size from ∼60 to ∼210 kb, characterized as FIIs and IncR. CONCLUSION: This report describes that the early stage of KPC-producing K. pneumoniae dissemination in Croatia is associated with a prolific PFGE type belonging to ST258. So far, the spread of an outbreak strain is limited to the northwest region of the country.

[Choice of antimicrobial drug for infections caused by Chlamydia trachomatis and Chlamydophila pneumoniae]. / Izbor antimikrobnog lijeka u lijecenju infekcija uzrokovanih bakterijama Chlamydia trachomatis i Chlamydophila pneumoniae.

Chlamydia (C.) trachomatis is the most common bacterial cause of sexually transmitted disease in the world. A well documented feature of chlamydial infection is its high rate of recurrence among sexually active populations. However, it is difficult to distinguish whether the high rate of recurrent disease is due to reinfection or to persistent infection with the same organism. Of particular concern in this era of increasing antibiotic resistance is whether persistent infection is the consequence of increasing resistance to standard antimicrobial therapy. Azithromycin and doxycycline are considered by the Centers for Disease Control and Prevention (CDC) as first line drugs for the treatment of chlamydial infections; erythromycin, ofloxacin and levofloxacin are recommended as alternative-regimen. Although C. trachomatis has been historically sensitive to these antibiotics, in vitro resistance is being increasingly reported. However, although in vitro antimicrobial resistance has been described, the clinical significance of these findings is unknown. C. pneumoniae is associated with community-acquired pneumonias, acute exacerbations of chronic bronchitis, otitis media, sinusitis and reactive airway disease. Persistent nasopharyngeal infection with C. pneumoniae has been documented in adults following acute respiratory infection. Chronic infection with C. pneumoniae has also been implicated in the pathogenesis of atherosclerosis, although this is still very controversial. Azithromycin, clarithromycin and quinolones are frequently used for the treatment of C. pneumoniae respiratory infections. Microbiologic failure has been described in C. pneumoniae infections, even after prolonged courses of azithromycin, erythromycin and doxycycline.

[Is the methicillin-resistant Staphylococcus aureus heteroresistant to vancomycin in Croatia?]. / Ima li u Hrvatskoj sojeva Staphylococcus aureus heterorezistentnih na vankomicin?

INTRODUCTION: Staphylococcus (S.) aureus with reduced susceptibility to vancomycin has attracted much attention all over the world since the first report of Staphylococcus aureus isolate intermediarily resistant to vancomycin (VISA) in Japan 1997. Other authors from different parts of the world have also described VISA isolates in patients with treatment failures after prolonged vancomycin therapy. Most of the isolates were heterogeneously resistant (hVISA), i. e. only a part of the population showed resistance and the rest showed susceptibility to vancomycin. AIM: Aim of the study was to determine the existence of methicillin-resistant S. aureus (MRSA) strains with reduced susceptibility to vancomycin in Croatia. METHODS: Abbreviated population analysis was used for detection of strains with reduced susceptibility to vancomycin. Forty-eight MRSA strains from three different hospitals in Croatia were tested on brain-heart infusion agar (BHIA) screen plate containing 4 mg/L vancomycin. Thirty-three (68.7%) strains that showed growth on a screen plate were inoculated on BHIA plates with rising vancomycin concentrations (1-20 mg/L). After subcultivation and growth on a vancomycin-free BHIA plate, minimal inhibitory concentrations (MICs) were determined for all strains. RESULTS: Fourteen of 48 (29.1%) strains had vancomycin 8 mg/L and 1/48 (2.0%) strain had vancomycin 16 mg/L. In 3/48 (6.2%) MIC were stable after storage in liquid nitrogen for six months. Vancomycin MIC50 and MIC90 of all 33 strains grown on screen plate were 1 and 2 gm/L, respectively, when tested on Mueller-Hinton agar (MHA) before inoculation on BHIA with growing concentrations of vancomycin. Immediately thereafter, MIC were 4 and 8 mg/L, and after six months of storage, they were 4 and 4 mg/L, respectively. CONCLUSION: The prevalence of hVISA in Croatia is low, but there are some strains with reduced susceptibility to vancomycin. Unfortunately, because of lack of clinical data neither clinical correlation with laboratory findings nor therapeutic failures can be discussed.

[Helicobacter pylori--bacterial characteristics]. / Helicobacter pylori--bakterioloske znacajke.

Helicobacter pylori lives in the gastric mucosa of about half of world population. H. pylori is a gram-negative, microaerophilic, facultatively acidophilic rod, very sensitive to drying and usual disinfectants. H. pylori strains show great genetic variability, the main mechanism of this phenomenon being in vivo genetic recombination. The principal virulence factors are: vacuolating cytotoxin, enzyme urease, motility, adhesive molecules on the cell surface, catalase and superoxide-dysmutase, receptor for human lactoferin and factors which promote proinflammatory cytokine secretion. Strains of H. pylori are sensitive to ampicillin and tetracycline; resistance to macrolide antibiotics is 7-15% in different parts of the world, and to metronidazole is 7-50% or even more. Because in vitro sensitivity of H. pylori is the most important factor for successful therapy, it is necessary to monitor this sensitivity continuously in a particular area.

[Helicobacter pylori--bacteriologic diagnosis and antibiotic sensitivity tests]. / Helicobacter pylori--bakterioloska dijagnostika i testiranje osjetljivosti na antibiotike.

Bacteriological diagnosis of Helicobacter pylori consists of culture from gastric biopsies, gastric juice, faeces and from specimens obtained from oral cavity, antigen stool assay and molecular diagnostic methods. In routine work culture is done from gastric biopsies. Other specimens are usually cultivated for research purposes. Culture constitutes the most specific way to establish the diagnosis of H. pylori infection. One of the major advantages of culture is that it allows sensitivity testing to drugs used in therapy. Culture also allows characterisation of H. pylori. Antigen stoll assay is a non-invasive diagnostic procedure, which should be evaluated. Molecular methods have confirmed their potential for epidemiological research and for the detection of resistant H. pylori, especially for macrolides. The clinical settings, local availability and economic considerations should guide use of bacteriological diagnostic methods.