Dissemination of blaOXA-58 in Proteus mirabilis isolates from Germany.

Objectives: Characterization of Proteus mirabilis isolates harbouring bla OXA-58 with emphasis on the genetic environment of this resistance determinant. Methods: Strains of P. mirabilis ( n = 37) isolated from different patients were tested for the presence of bla OXA-58 . The genetic context of bla OXA-58 was determined by WGS of two strains and Sanger sequencing. Clonality of the strains was assessed by PFGE. Susceptibility testing was performed by microdilution according to EUCAST. Results: Four strains isolated in different geographical regions of Germany were positive for bla OXA-58 , and WGS showed that this resistance gene was harboured on a plasmid. Sanger sequencing confirmed the presence of two nearly identical plasmids, 6219 and 6208 bp in size, in all four strains. Upstream of bla OXA-58 an IS Aba 3-like transposase gene was located. The P. mirabilis strains were not clonally related according to PFGE. MICs of meropenem for three of the strains were only just above the EUCAST breakpoint and the Carba NP test was positive for only two of the strains. Conclusions: To our knowledge, this is the first description of bla OXA-58 in the species P. mirabilis . The resistance gene is harboured by almost identical plasmids in strains not clonally related and from different geographical regions. Apart from an IS Aba 3-like transposase gene upstream of bla OXA-58 the genetic context is different from bla OXA-58 harboured on plasmids in the genus Acinetobacter . With MICs of meropenem well below the EUCAST breakpoint or only just above it and equivocal or false negative results from the Carba NP test, bla OXA-58 can be easily overlooked in P. mirabilis .

Compared with Cotrimoxazole Nitroxoline Seems to Be a Better Option for the Treatment and Prophylaxis of Urinary Tract Infections Caused by Multidrug-Resistant Uropathogens: An In Vitro Study.

The resistance of uropathogens to various antibiotics is increasing, but nitroxoline remains active in vitro against some relevant multidrug resistant uropathogenic bacteria. E. coli strains, which are among the most common uropathogens, are unanimously susceptible. Thus, nitroxoline is an option for the therapy of urinary tract infections caused by multiresistant bacteria. Since nitroxoline is active against bacteria in biofilms, it will also be effective in patients with indwelling catheters or foreign bodies in the urinary tract. Cotrimoxazole, on the other hand, which, in principle, can also act on bacteria in biofilms, is frequently inactive against multiresistant uropathogens. Based on phenotypic resistance data from a large number of urine isolates, structural characterisation of an MDR plasmid of a recent ST131 uropathogenic E. coli isolate, and publicly available genomic data of resistant enterobacteria, we show that nitroxoline could be used instead of cotrimoxazole for intervention against MDR uropathogens. Particularly in uropathogenic E. coli, but also in other enterobacterial uropathogens, the frequent parallel resistance to different antibiotics due to the accumulation of multiple antibiotic resistance determinants on mobile genetic elements argues for greater consideration of nitroxoline in the treatment of uncomplicated urinary tract infections.

Performance of a matrix-assisted laser desorption ionization-time-of-flight mass spectrometry system for the identification of bacterial isolates in the clinical routine laboratory.

BACKGROUND: Matrix-Assisted Laser Desorption Ionization-Time-of-Flight Mass Spectrometry (MALDI-TOF MS) has emerged as a new tool for the fast and reliable identification of microorganisms. We evaluated the performance of a MALDI-TOF MS-system for the identification of various clinical isolates in the routine microbiology setting. MATERIAL AND METHODS: For the evaluation study a set of 1116 bacterial isolates were collected in the routine microbiology laboratory. Additonally 108 isolates of strain culture collections (ATTC, DSMZ) were utilized. Identification of the bacterial isolates was perfomed with a Microflex LT mass spectrometer in combination with the MALDI-Biotyper 2.0 software (Bruker Daltonik GmbH, Bremen, Germany). The results of the MALDI-TOF MS were compared to phenotypic bacterial identification systems used in our routine laboratory. Discrepancies were resolved by 16 S rDNA-sequencing. RESULTS: Of the 108 reference strains tested, 101 (93.5%) were correctly identified to species level. Overall, 1062 (95.2%) of the 1116 strains collected in the routine laboratory were correctly identified with the MALDI-Biotyper. Accuracy for the identification of Enterobacteriaceae, non-fermenting gram-negative rods, staphylococci, enterococci and streptococci with the MALDI-Biotyper was 95.5%, 79.7%, 99.5%, 100% and 93.7%, respectively. Results were available in 12 minutes for direct smear and in 20 min with an extraction method. CONCLUSIONS: The MALDI-TOF method proves to be a fast and reliable method for the identification of the most important bacterial isolates in the clinical laboratory.

Genetic diversity of Legionella pneumophila in hospital water systems.

It has been shown that different patients who had acquired legionellosis in a hospital setting were infected with the same strain even years apart. However, there are no longitudinal data describing the molecular epidemiology of Legionella pneumophila strains that contaminate a water system. This raised the question if there are any shifts of L. pneumophila strains over time, or after carrying out control measures. Using genotyping on a large collection of isolates, we investigated in a retrospective study the distribution of L. pneumophila serogroups and PFGE types in six different hospitals of the University of Heidelberg between 1991 and 2001. A total of 2012 water samples were drawn for routine testing and for evaluation of control measures, 747 samples were positive for L. pneumophila. Serogroups were determined by latex agglutination or by direct fluorescence assay; and 515 L. pneumophila isolates from water systems and six from patients underwent PFGE typing after SfiI-restriction. We identified seven serogroups and 19 genotypes among the water isolates. Each hospital had one to four predominating PFGE types that were stable over the investigation period. The oldest buildings in hospitals 4 and 5 (built 1876 and 1907) had more types than the newest one (built 1986). In all hospitals PFGE types were identified that could be found only sporadically. Although each hospital had its own warm water supply, we identified types that could be found in more than one hospital. However, there was no overlap of types in buildings that were fed from different wells. Infrequently occurring nosocomial legionellosis (n=3) were only caused by predominant strains. Contamination of water supplies seemed to be dominated by stable genotypes, even after various control measures. Additional genotypes could be isolated sporadically, however, their pathogenetic relevance seemed to be questionable.

Antibiotic-Resistant E. coli in Uncomplicated Community-Acquired Urinary Tract Infection.

BACKGROUND: Routine urine culture testing is not recommended for uncomplicated urinary tract infections (UTIs). As a result, the antibiotic resistance patterns or the organisms causing UTIs are not adequately reflected in routine data. We studied the sensitivity of Escherichia coli (E. coli) to trimethoprim (TMP) and to cotrimoxazole (i.e., trimethoprim/sulfamethoxazole, TMP/SMX) in community-acquired UTI and compared the findings with the resistance data of the Antimicrobial Resistance Surveillance System (ARS). METHODS: General practitioners and internists in private practice prospectively recruited all of their adult patients with symptoms of a urinary tract infection from May 2015 to February 2016. Urine specimens from all patients were tested (including urine culture testing and antibiotic susceptibility) and infections were defined as uncomplicated or complicated UTIs. RESULTS: 1245 participants from 58 medical practices were enrolled in the study. Pathogenic organisms were found in the urine of 877 patients, of whom 74.5% had E. coli infections. Among the E.-coli-positive UTIs, 52.4% were classified as uncomplicated and 47.6% as complicated. The prevalence of E. coli that was resistant to TMP and to TMP/SMX in uncomplicated UTIs was 15.2% and 13.0%, respectively, compared to 25.3% and 24.4%, respectively, from all UTIs in ARS in 2015. Study participants who had previously taken antibiotics had the highest prevalence of E. coli resistance (30.9%), followed by those who had two or more UTIs within the past six months (28.9%). CONCLUSION: E. coli with resistance to TMP was significantly less prevalent among the study patients with uncomplicated UTIs than in the routine data of the ARS. Accordingly, TMP should still be considered as an option for the treatment of uncomplicated UTIs. TMP/SMX is considered the agent of second choice because of its side effects. Surveillance systems based on routine data do not yield a representative sample for the evaluation of the resistance situation in patients with uncomplicated UTIs.

Longitudinal study of the molecular epidemiology of methicillin-resistant Staphylococcus aureus at a university hospital.

Surveillance for methicillin-resistant Staphylococcus aureus (MRSA) at the University Hospital of Heidelberg revealed an increase in the numbers of newly detected MRSA isolates in recent years. We conducted a study to assess the dynamics of the changes in the MRSA population. Pulsed-field gel electrophoresis (PFGE) typing of MRSA isolates from all patients at the University Hospital of Heidelberg collected between 1993 and 2004 was performed. The microbiology database contained 1,807 entries for newly detected MRSA isolates from 1,301 patients. A total of 1,252 isolates were available for PFGE typing. The isolates could be classified into 109 different PFGE types. Most PFGE types (n=70) were detected less than five times and showed no evidence of transmission (sporadic strains). They accounted for 8.7% of all isolates, with few variations in frequency over the time. Thirty-seven PFGE types were clustered by time of detection, and transmission of the strains was likely (local epidemic strains). A total of 37.3% of the isolates belonged to this group of strains. The remaining 54.0% of the isolates belonged to only two further PFGE types (endemic strains). One endemic strain accounted for 5.0% of all isolates in 1994 and 68.2% in 2004. A second endemic strain was detected in 1.1% of all isolates in 1998 but in 12.4% in 2004. Statistical analysis of the associations between the kind of strain (sporadic, local epidemic, or endemic) and the patients' characteristics revealed a significant association for age and mode of acquisition. The remarkable increase in the rate of MRSA detection at the University Hospital of Heidelberg is mainly due to the dissemination of two different strains. Infection control measures seemed sufficient to prevent further transmission of some but not all of the strains.