D. Jonas

Development of a Multilocus Sequence Typing Scheme for the Opportunistic Pathogen Pseudomonas aeruginosa

ABSTRACT A multilocus sequence typing (MLST) scheme has been developed for Pseudomonas aeruginosa which provides molecular typing data that are highly discriminatory and electronically portable between laboratories. MLST data confirm the data from previous studies that suggest that P. aeruginosa is best described as nonclonal but as having an epidemic population. The index of association was 0.17, indicating a freely recombining population; however, there was evidence of clusters of closely related strains or clonal complexes among the members of this population. It is apparent that the sequence types (STs) from single isolates, representing each of the present epidemic clones in the United Kingdom from Liverpool, Manchester, and the West Midlands, are not closely related to each other. This suggests distinct evolutionary origins for each of these epidemic clones in the United Kingdom. Furthermore, these clones are distinct from European clone C. Comparison of the results of MLST with those of toxA typing and serotyping revealed that strains with identical STs may possess different toxA types and diverse serotypes. Given that recombination is important in the population of P. aeruginosa, the lack of a linkage between toxA type and serotype is not surprising and reveals the strength of the MLST approach for obtaining a better understanding of the epidemiology of P. aeruginosa.

Rapid PCR-Based Identification of Methicillin-Resistant Staphylococcus aureus from Screening Swabs

ABSTRACT A PCR identification of methicillin-resistant Staphylococcus aureus (MRSA), obviating the need for subculture on agar media, was investigated. The combination of MRSA detection by mecA femB PCR with prior enrichment in selective broth was tested for 439 swabs. PCR identified 36 MRSA-positive samples, in concordance with conventional methods.

Spread of ampicillin/vancomycin-resistant Enterococcus faecium of the epidemic-virulent clonal complex-17 carrying the genes esp and hyl in German hospitals.

The incidence of vancomycin-resistant Enterococcus faecium isolation was low (≤5%) in German hospitals before 2003. Within the second half of 2003 and the first half of 2004, however, increasing frequencies of up to 14% were noticed in several hospitals in southwestern Germany. This increase was attributed mainly to the occurrence and spread of epidemic-virulent ampicillin/vancomycin-resistant, vanA- and vanB-positive E. faecium clones, most of which exhibited the virulence factors enterococcal surface protein (esp) and bacteriocin activity and some which exhibited hyaluronidase (hyl). E. faecium possessing hyaluronidase was initially found in U.S. hospitals and recently detected in several European hospitals and, subsequently, in German hospitals as well. Ampicillin/vancomycin-resistant E. faecium clones originating mainly from southwestern German hospitals were characterized by multilocus sequence typing since different sequence types (STs) belonging to the clonal complex-17 are currently disseminated worldwide. Multilocus sequence typing revealed that, in 1998 and 1999, ampicillin/vancomycin-resistant E. faecium clone ST-117 was prevalent in various German hospitals, while in 2003 and 2004, clone ST-203 dominated in several hospitals located in southwestern Germany. Both sequence types display single-locus variants of ST-78, which was frequently recorded in various Italian hospitals between 2000 and 2003, and all of these STs belong to the clonal complex-17. Expression of linezolid resistance was observed in ampicillin/glycopeptide-resistant E. faecium strains (VanA type) from two tertiary hospitals in southwestern Germany due to mutations in domain V of the 23S rDNA (G2576T). While in one hospital the resistance emerged during linezolid therapy, in the other hospital resistance was caused by transfer of an identical linezolid/ampicillin/glycopeptide-resistant E. faecium strain. In conclusion, it is very important to monitor the occurrence of epidemic-virulent clonal complex-17 strains of E. faecium to prevent their spread in hospitals, especially if they are resistant to glycopeptides and linezolid.

How many infections are caused by patient-to-patient transmission in intensive care units?*

Objective:The proportion of intensive care unit (ICU)-acquired infections that are a consequence of nosocomial cross-transmission between patients in tertiary ICUs is unknown. Such information would be useful for the implementation of appropriate infection control measures. Design:A prospective cohort study during 18 months. Setting:Five ICUs from two university hospitals. Patients:All patients admitted for ≥48 hrs. Measurement:ICU-acquired infections were ascertained during daily bedside patient and chart reviews. Episodes of potential cross-transmission were identified by highly discriminating genetic typing of all clinical and surveillance isolates of the ten bacterial species most frequently associated with nosocomial infections in ICUs. Isolation of indistinguishable isolates in two or more patients defined potential transmission episodes. Main Results:During 28,498 patient days, 431 ICU-acquired infections and 141 episodes of nosocomial transmissions were identified. A total of 278 infections were caused by the ten species that were genotyped, and 41 of these (14.5%) could be associated with transmissions between patients. Conclusion:Infections acquired during treatment in modern tertiary ICUs are common, but a causative role of direct patient-to-patient transmission can only be ascertained for a minority of these infections on the basis of routine microbiological investigations.

Design of a Surveillance System of Antibiotic Use and Bacterial Resistance in German Intensive Care Units (SARI)

Abstract.Background: Data on antibioticnconsumption and bacterial resistance are important fornbenchmarking, ensuring quality of antibiotic treatment andnhelping to understand the relationship between the use ofnantibiotics and the emergence of resistance.nMethods: The SARI projectnis an ecological study that has established laboratory-basednsurveillance in German intensive care units (ICU). Resistancenrates of 13 sentinel pathogens are reported and certain alertnorganisms are sent for genotyping and retesting of antimicrobialnresistance.nResults: The project,ninitiated in February 2000, now includes 35 ICUs generating antotal of 266,013 patient days, 354,356 defined daily doses (DDD)nand providing susceptibility data on 21,354 isolates. Poolednantibiotic usage density (AD = DDD/1,000 patient days) wasnhighest for penicillins with lactamase inhibitor (AD 338.3)nfollowed by quinolones (AD 155.5) and second-generationncephalosporins (AD 124.6). Total AD was calculated as 1,337nDDD/1,000 patient days. Resistance rates (RR) for laboratoriesntesting according to the German Industrial Standard (DIN) weren19.3% for methicillin-resistant Staphylococcus aureus(MRSA), 9.5% fornciprofloxacinresistant Escherichiancoli and 25.4% for imipenem-resistantnPseudomonas aeruginosa. 40%nof the laboratories did not identify the extended spectrumnβlactamase production of a Klebsiellanpneumoniae strain.nConclusion: Focusing onnGerman ICUs, the SARI surveillance system provides a conceptnthat produces a benchmark for the link between antibioticnresistance and consumption.

Designation of the European Working Group on Legionella infection (EWGLI) amplified fragment length polymorphism types of Legionella pneumophila serogroup 1 and results of intercentre proficiency testing using a standard protocol

Abstract.The utility of amplified fragment length polymorphism (AFLP) analysis as a genotyping method for the epidemiological typing of Legionella pneumophila serogroup 1 has been previously demonstrated. This study (i) reports recommendations for the designation of the European Working Group on Legionella Infections (EWGLI) AFLP types, (ii) describes the EWGLI AFLP types identified for the 130 strains in the EWGLI culture collection, and (iii) reports the results of a newly introduced international programme of proficiency testing. Following preliminary analysis of 20 epidemiologically unrelated isolates, 16 major AFLP types were identified. A coded proficiency panel, comprising 12 additional isolates representing 9 of these 16 AFLP types, was sent to 17 centres in 14 European countries where it was analysed following a previously determined standard protocol. The identity of each coded strain (recorded as AFLP type 001–016 or untypeable) was determined by participants with reference to these 16 AFLP types, either visually or using gel analysis software where available, and reported to the coordinating centre. Nine of the 12 strains, including an epidemiologically related pair and two pairs of unrelated isolates of the same type, were correctly identified to the correct AFLP type by all or all but one of the participants. Seven laboratories correctly identified all 12 isolates, and a further seven laboratories correctly identified 11. Type identification scores ranged from 75% (1 centre), 83% (2 centres), and 92% (7 centres) to 100% (7 centres). The AFLP method as described is robust and rapid and allows the genotypic comparison of isolates of Legionella pneumophila between different testing centres without the need for exchange of the strains studied.

Effect of skin disinfection with octenidine dihydrochloride on insertion site colonization of intravascular catheters.

Abstract.Background: We investigated the efficacy of two commercially available, alcohol-based antiseptic solutions in decontaminating the insertion site of central lines. One solution contained the bispyridine octenidine dihydrochloride.nPatients and Methods: Inpatients receiving either a central venous catheter (CVC) or a peripherally inserted central catheter (PICC) were alternately assigned to different skin disinfection regimens at the insertion site: (A) 0.1% octendine dihydrochloride with 30% 1-propanol and 45% 2-propanol, (B) 74% ethanol with 10% 2-propanol. Quantitative skin cultures were obtained from the insertion site at predetermined intervals.nResults: A total of 60 patients received 12 CVCs and 47 PICCs (no significant difference with respect to gender, age and catheter type). In total, 90 cultures were assessed in each group. The median colony-forming unit (cfu) counts per 24 cm2 (group A vs B) were 2,270 vs 2,950 before, 20 vs 40 following and 860 vs 1,210 24 h after catheter insertion, respectively. A statistically significant difference in the efficacy of skin decontamination was seen between groups in culture set (3) and in the difference between culture sets (2) and (3) (Wilcoxon rank sum test).nConclusion: Octenidine/propanol appears to be more effective than alcohol (ethanol/propanol) alone in reducing microflora of the skin at the PICC/CVC insertion site over a 24-h period.

Evaluation of the mecA femB Duplex Polymerase Chain Reaction for Detection of Methicillin-Resistant Staphylococcus aureus

Abstractu2002This study systematically evaluated a recently described duplex polymerase chain reaction test for methicillin-resistant Staphylococcus aureus with 25 different German epidemic strains of methicillin-resistant Staphylococcus aureus and 66 staphylococci other than methicillin-resistant Staphylococcus aureus, including 17 different coagulase-negative staphylococcal species and subspecies, that were either oxacillin susceptible or oxacillin resistant. The results were compared with those of conventional cultural identification and susceptibility testing. Of the 91 isolates tested, all 25 confirmed strains of methicillin-resistant Staphylococcus aureus were identified correctly. None of the remaining strains of methicillin-susceptible Staphylococcus aureus was misidentified as methicillin-resistant Staphylococcus aureus. It was concluded that the duplex polymerase chain reaction appears to offer a time-saving and accurate method of detection of methicillin-resistant Staphylococcus aureus.

[SARI: surveillance of antibiotic use and bacterial resistance in German intensive care units. Correlation between antibiotic use and the emergence of resistance].

ZusammenfassungIntensivstationen (ITS) gelten als Hochrisikobereiche fürndie Entstehung und Ausbreitung multiresistenter bakteriellernErreger. Bisher gibt es in Deutschland weder repräsentativenepidemiologische Daten über Antibiotikaresistenzen aufnIntensivstationen noch über den Verbrauch von Antibiotika aufnIntensivstationen oder die Korrelation zwischennAntibiotikaverbrauch und Resistenzentwicklung. Im Projekt SARIn(Surveillance der Antibiotikaanwendung und bakteriellennResistenzen auf Intensivstationen), das vom Bundesministeriumnfür Bildung und Forschung als Teil desninfektionsepidemiologischen Netzwerkes Spread of NosocomialnInfections and Resistant Pathogens (SIR) gefördert wird, werdennseit Februar 2000 Daten zu Antibiotikaverbrauch undnResistenzraten auf bundesweit mittlerweile 38ninterdisziplinären, medizinischen und chirurgischennIntensivstationen erfasst. Im Zeitraum von Februar 2000–Junin2003 wurden in 1.142 Teilnahmemonaten und 413.065 Patiententagenn550.288 Antibiotikatagesdosen (DDD, defined daily doses nachnWHO) verabreicht bei einer mittleren Antibiotikaanwendungsdichtenvon 1.335 DDDs/1.000 Patiententage sowie Resistenzdaten vonn37.612 Isolaten von Intensivstationen erfasst. Nebennsignifikanten Korrelationen von Ciprofloxacin-Anwendung und MRSAnzeigte sich bei Imipenem-Einsatz und Imipenem-resistentennP. aeruginosa, dass dienGenodiversität von P.naeruginosa auf ITS mit hohen Resistenzraten undnniedrigem Imipenem-Verbrauch deutlich niedriger lag—alsnindirekter Hinweis für eine Übertragung identischer Stämme—alsnauf ITS mit gleichzeitig hohen Resistenzraten und hohemnVerbrauch. Die infektionsepidemiologischen Daten von SARI sindnfür Intensivstationen eine Orientierungshilfe für einnverbessertes Antibiotika- und Hygienemanagementn(http://www.sari-antibiotika.de).AbstractIntensive care units (ICUs) are considered to be high-risknareas for the emergence and spread of multiresistant bacterialnpathogens. In Germany, there are no representativenepidemiological data on antibiotic resistance, on the use ofnantibiotics in ICUs, or on the correlation between antibioticnuse and the emergence of resistance. Project SARI (surveillancenof antibiotic use and bacterial resistance in ICUs), which as anpart of the epidemiological network Spread of NosocomialnInfections and Resistant Pathogens (SIR) is supported by thenGerman Ministry of Science and Education, started in Februaryn2000 and meanwhile includes data on antibiotic use andnresistance rates in 38 medical, surgical, and interdisciplinarynICUs. To date (February 2000–June 2003), a total of 1142 months,n413,065 patient days, and 550,288 defined daily doses (DDDs innaccordance with the WHO) have been covered with a meannantibiotic usage density (AD) of 1335 DDDs/1000 patient days andnresistance data on 37,612 isolates from ICUs. Ciprofloxacin usenand MRSA correlate significantly, as do imipenem use and thenrate of imipenemresistant P.naeruginosa.The genodiversity ofnP. aeruginosa is lower innICUs with high resistance rates and low use of imipenem than innICUs with high resistance rates and high use. This is annindirect parameter of transmission of identical strains.Thenepidemiological data of SARI form a basis for improvednantibiotic and infection control management in ICUsn(http://www.sari-antibiotika.de).

Tea as a source of Acinetobacter baumannii ventilator-associated pneumonia?

To the Editor: Acinetobacter baumannii increasingly has been involved as an agent of hospital outbreaks worldwide. The most common site of nosocomial infections is the respiratory tract, especially in ventilated patients, followed by bloodstream infections. 1 The incidence of Acinetobacter species as a cause of nosocomial pneumonia has increased despite advances in the management of ventilated patients and the use of better disinfection procedures for ventilatory equipment. Spread of Acinetobacter via hands of staff members was found to be important in many studies. 2 Outbreaks due to contaminated medical equipment and materials, including mattresses and pillows, also have been reported, 3 but tea or other fluids used for mouth hygiene have not previously been reported as a source of infections caused by Acinetobacter species. The emergence of vancomycin-resistant Staphylococcus aureus in the United States and Japan has rein-tensified efforts to use antimicro-bials more judiciously, but coming up with effective ways to reduce the use of vancomycin in hospitals has proven to be a tough challenge. To evaluate antimicrobial use across the country, Fridkin and colleagues surveyed 108 adult ICUs in 41 US hospitals to find out how much van-Germany) was isolated in our neuro-logical intensive-care unit from tra-cheal secretions (39 patients), a cere-brospinal fluid specimen, and a skin swab. All isolates but one were sensitive to cotrimoxazole. Ventilator-associated pneumonia caused by A baumannii, alone or in combination with other pathogens, was diagnosed in 18 patients. There was one case of relapsing Acinetobacter ventriculo-peritoneal shunt infection. Genotyping by randomly amplified polymorphic DNA-polymerase chain reaction revealed 10 genetically different strains, 6 of which were involved in small clusters of colonized or infected patients. 4 Sampling of 288 environmental sites (including hands of personnel) revealed three strains isolated from tapwater and from anti-splash nozzles that were identical to those found in three patients. Contaminated respiratory equipment or contamination of the patients inanimate environment could not be identified. One of the outbreak strains also was isolated from tea used for mouth care. Native tea was found to be heavily contaminated with a wide range of gram-negative bacteria, but not with A baumannii. Contamination of the brewed tea may have occurred due to mixing the comycin they used during 1996 to 1997, as well as what proportion of their total S aureus isolates were resistant to methicillin. The median rate of vancomycin use was found to be lowest in coronary care ICUs and highest in …