Gernot Zarfel

ESBL-producing E. coli in Austrian sewage sludge

The aim of this study was to investigate the degree of contamination of sewage sludge with ESBL-producing Escherichia coli strains and the effectiveness of different sewage sludge treatment methods. Monthly sewage sludge samples were collected between January and September 2009 in 5 different sewage treatment plants and tested for the presence of ESBL E. coli. In addition, the number of colony forming units (CFU) of E. coli and coliform bacteria before and after the different sludge treatment methods (aerobic/anaerobic digestion, lime stabilization, and thermal treatment) was investigated. Of the 72 sewage sludge samples investigated, ESBL-positive E. coli were found in 44 (61.1%) sewage sludge samples. The classification of beta-lactamase groups was carried out in 15 strains resulting in the detection of 2 different groups (CTX-M and TEM) of bla genes. All 15 of them had a CTX-M gene and 4 of these strains furthermore carried a TEM gene. With regard to the CFU of E. coli and coliform bacteria, thermal treatment and lime stabilization following dehydration sufficiently reduced pathogen concentrations. The plants using merely stabilization and dehydration showed an increase of E. coli and coliform bacteria and thus also an increase in ESBL-producing E. coli.

Orally administered colistin leads to colistin-resistant intestinal flora and fails to prevent faecal colonisation with extended-spectrum β-lactamase-producing enterobacteria in hospitalised newborns.

Colonisation and infection with extended-spectrum β-lactamase-producing Enterobacteriaceae (ESBL-E) is an emerging problem. The aim of this study was to investigate whether colistin, which is reported to be effective against multiresistant enterobacteria, prevents ESBL-E colonisation in neonates. For prophylaxis of necrotising enterocolitis, oral gentamicin (15 mg/kg/day) is routinely used in all neonates hospitalised at the Neonatal Intensive Care Unit of University Hospital Graz (Austria). During the study period from May 2005 to September 2007, three ESBL-E outbreaks (total duration 18 months) occurred. During these outbreaks, gentamicin was immediately replaced by oral colistin (8 mg/kg/day) in all hospitalised neonates. All neonates colonised with ESBL-E during the study period were retrospectively analysed with regard to the influence of colistin on ESBL-E colonisation. Genetic relatedness of isolates was assessed by repetitive sequence-based polymerase chain reaction (rep-PCR). During the study period, 30 (4.5%) of 667 neonates were colonised with ESBL-E. Twelve of twenty-one patients colonised with Klebsiella pneumoniae (ESBL-Kp) and one of nine patients colonised with Klebsiella oxytoca (ESBL-Ko) had received oral colistin at time of colonisation with ESBL-E. Amongst ESBL-Kp, the rate of colistin resistance was significantly higher in the colistin group (P=0.0075). Four different clones of ESBL-Kp and three different clones of ESBL-Ko were isolated, indicating the occurrence of patient-to-patient transmission. Colistin-resistant as well as colistin-susceptible isolates were detected within the same clones, indicating induction of resistance. At the dosage used, oral colistin did not prevent colonisation with ESBL-E and appeared to select colistin-resistant strains or to induce colistin resistance.

Occurrence and genotyping using automated repetitive-sequence–based PCR of methicillin-resistant Staphylococcus aureus ST398 in Southeast Austria☆☆☆

In this retrospective study, the occurrence and genetic relatedness of methicillin-resistant Staphylococcus aureus (MRSA) ST398 in Austrian MRSA patients was investigated. From 2002 to 2008, 14 MRSA ST398 were detected. First occurrence of MRSA ST398 was already found in 2004. Spa ribotyping assigned 12 isolates to spa type t011 and 1 each to spa type t034 and spa type t1451. Isolated MRSA ST398 was nontypeable by pulsed-field gel electrophoresis (NT-MRSA) using restriction enzyme SmaI; therefore, genotyping was performed using automated repetitive-sequence-based PCR (rep-PCR) on the DiversiLab system. Rep-PCR results assigned 10 (71%) of the 14 MRSA ST398 into 1 cluster with a similarity >95%; there was 1 cluster consisting of 2 isolates with a similarity >99% and 2 unique MRSA ST398 isolates. In conclusion, MRSA ST398 was continuously detected in Southeast Austria; first in 2004 with up to 5 MRSA ST398 isolates in 2008. Automated rep-PCR proved as a reliable technique in determining genetic relatedness of NT-MRSA ST398 and demonstrates clonal spread of MRSA ST398 in the investigated region.

Contaminated Handwashing Sinks as the Source of a Clonal Outbreak of KPC-2-Producing Klebsiella oxytoca on a Hematology Ward

ABSTRACT We investigated sinks as possible sources of a prolonged Klebsiella pneumonia carbapenemase (KPC)-producing Klebsiella oxytoca outbreak. Seven carbapenem-resistant K. oxytoca isolates were identified in sink drains in 4 patient rooms and in the medication room. Investigations for resistance genes and genetic relatedness of patient and environmental isolates revealed that all the isolates harbored the blaKPC-2 and blaTEM-1 genes and were genetically indistinguishable. We describe here a clonal outbreak caused by KPC-2-producing K. oxytoca, and handwashing sinks were a possible reservoir.

Comparison of extended-spectrum-β-lactamase (ESBL) carrying Escherichia coli from sewage sludge and human urinary tract infection

For many years, extended-spectrum-beta-lactamase (ESBL) producing bacteria were a problem mainly located in medical facilities. Within the last decade however, ESBL-producing bacteria have started spreading into the community and the environment. In this study, ESBL-producing Escherichia coli from sewage sludge were collected, analysed and compared to ESBL-E. coli from human urinary tract infections (UTIs). The dominant ESBL-gene-family in both sample groups was bla(CTX-M), which is the most prevalent ESBL-gene-family in human infection. Still, the distribution of ESBL genes and the frequency of additional antibiotic resistances differed in the two sample sets. Nevertheless, phenotyping did not divide isolates of the two sources into separate groups, suggesting similar strains in both sample sets. We speculate that an exchange is taking place between the ESBL E. coli populations in infected humans and sewage sludge, most likely by the entry of ESBL E. coli from UTIs into the sewage system.

Emergence of carbapenem-resistant Enterobacteriaceae in Austria, 2001–2010

We report the emergence of carbapenem-resistant Enterobacteriaceae in Austria. Over a 10-year period, carbapenem-resistant Enterobacteriaceae isolates were obtained from 13 hospitalized patients, with the first isolation in the year 2005 and a remarkable increase in the number of involved patients in 2010. Carbapenem-resistant Enterobacteriaceae comprise eight Klebsiella pneumoniae isolates, four Klebsiella oxytoca isolates, and one Escherichia coli isolate. The detected carbapenemases were the metallo-β-lactamases New Delhi β-lactamase, VIM and IMP, and the serin-β-lactamase Klebsiella pneumoniae carbapenemase.

Nosocomial Outbreak of Klebsiella pneumoniae Carbapenemase-Producing Klebsiella oxytoca in Austria

ABSTRACT To date, no outbreak of carbapenemase-producing bacteria has been reported for Austria. While outbreaks of Klebsiella pneumoniae carbapenemase (KPC)-producing K. pneumoniae have been increasingly reported, no outbreak caused by KPC-producing Klebsiella oxytoca has been described yet, to the best of our knowledge. We report an outbreak of KPC-producing K. oxytoca. In 5 months, 31 KPC-producing Klebsiella oxytoca strains were isolated from five patients. All patients were admitted to the same medical intensive care unit in Austria.

Fecal carriage and intrafamilial spread of extended-spectrum β-lactamase-producing enterobacteriaceae following colonization at the neonatal ICU.

Objective: Fecal carriage of extended-spectrum &bgr;-lactamase-producing enterobacteriaceae may contribute to the spread of extended-spectrum &bgr;-lactamase-producing enterobacteriaceae into the community. The objective of this study was to assess the duration of fecal carriage after discharge and the occurrence of intrafamilial transmission. Design: Case series. Setting: Quaternary care children’s hospital. Patients: Patients colonized with extended-spectrum &bgr;-lactamase-producing enterobacteriaceae at the neonatal ICU and the respective household members. Interventions: Screening for intestinal extended-spectrum &bgr;-lactamase-producing enterobacteriaceae colonization was done at 1, 2, 4, 6, 9, and 12 months after discharge. Genetic relatedness of isolated extended-spectrum &bgr;-lactamase-producing enterobacteriaceae strains was determined using automated rep-PCR. Results: Twenty-five neonates (case-patients) colonized with extended-spectrum &bgr;-lactamase-producing enterobacteriaceae (one extended-spectrum &bgr;-lactamase-Escherichia coli; six extended-spectrum &bgr;-lactamase-Klebsiella pneumoniae; 11 extended-spectrum &bgr;-lactamase-Klebsiella oxytoca; and seven extended-spectrum &bgr;-lactamase-Serratia marcescens) were included. Duration of fecal carriage was longer (up to 1 yr) in case-patients colonized with Klebsiella species than in case-patients colonized with Serratia marcescens (<4 months). During follow-up, strains and species of extended-spectrum &bgr;-lactamase-producing enterobacteriaceae different from the primary strain were found in four and three case-patients, respectively. In nine of 49 (18.4%) included household members, extended-spectrum &bgr;-lactamase-producing enterobacteriaceae were found during the follow-up period. In two of nine colonized household members, the isolated extended-spectrum &bgr;-lactamase-producing enterobacteriaceae was identical to the primary strains of the respective case-patients. Conclusions: After intestinal colonization with extended-spectrum &bgr;-lactamase-producing enterobacteriaceae at the neonatal ICU, infants potentially remain carriers during the first year after discharge. Intrafamilial spread has been proven.

Antimicrobial activity of gentamicin palmitate against high concentrations of Staphylococcus aureus

The reduction of implant related infections plays a pivotal role in orthopaedic surgery as an increasing number of people require implants (up to 200,000 per year in the United States (source: Joint Implant Surgery & Research Foundation 2010)). The aim of the current study is to prevent and thus decrease the number of bacterial infections. Both pre and post operative systemic antibiotic treatment and gentamicin containing bone cements (polymethylmethacrylate, PMMA) are commonly used strategies to overcome infections. In this study, the antimicrobial efficacy of gentamicin sulfate loaded bone cement was compared with titan discs coated with a new form of gentamicin, gentamicin palmitate. Adherence prevention, killing rates and killing kinetics were compared in an in vitro model, using Staphylococcus aureus (S. aureus), which together with Staphylococcus epidermidis (S. epidermidis) represents 60% of bacteria found responsible for hip implant infections (An and Friedman, 1996, J Hosp Infect 33(2):93–108). In our experiments gentamicin, which was applied as gentamicin palmitate on the surface of the implants, showed a high efficacy in eliminating bacteria. In contrast to gentamicin sulfate containing bone cements, gentamicin palmitate is released over a shorter period of time thus not inducing antibiotic resistance. Another benefit for clinical application is that it achieves high local levels of active ingredient which fight early infections and minimize toxic side effects. Furthermore, the short term hydrophobic effect of gentamicin palmitate can successfully impede biofilm formation. Thus, the use of self-adhesive antibiotic fatty acid complexes like gentamicin palmitate represents a new option for the anti-infective coating of cementless titan implants.

Resistance patterns of Escherichia coli isolated from sewage sludge in comparison with those isolated from human patients in 2000 and 2009

For some time now, antibiotic-resistant bacterial strains have been found in the human population, in foods, in livestock and wild animals, as well as in surface waters. The entry of antibiotics and resistant bacterial strains into the environment plays an important role in the spread of antibiotic resistance. The goal of the present study was to monitor the entry of antibiotic resistances into the environment through the contamination of wastewater. To assess the extent of transmission of antibiotic resistances from human sources into the environment, the resistance patterns of Escherichia coli strains isolated from human patients have been compared to those found in strains isolated from sewage sludge. Our results may indicate if resistances to particular antibiotics are more prone than others to spread into the environment. To monitor the increase of specific resistances over time, samples taken in the years 2000 and 2009 were analysed. Our study shows that for some antibiotics a parallel development of resistance patterns has taken place in both patient and environmental samples over time. For other sets of antibiotics, independent developments have occurred in the samples. A clear increase of multi-resistant E. coli strains over time was observed in samples from both sources.