Acetic acid as a decontamination method for sink drains in a nosocomial outbreak of metallo-ß-lactamase-producing Pseudomonas aeruginosa.

BACKGROUND: Pseudomonas aeruginosa may colonize water systems via biofilm formation. In hospital environments, contaminated sinks have been associated with nosocomial transmission. Here we describe a prolonged outbreak of a metallo-ß-lactamase-producing P. aeruginosa (Pae-MBL) associated with sink drains, and propose a previously unreported decontamination method with acetic acid. AIM: To describe a nosocomial outbreak of Pae-MBL associated with hospital sink drains and to evaluate acetic acid as a decontamination method. METHODS: The outbreak was investigated by searching the microbiology database, microbiological sampling and strain typing. Antibacterial and antibiofilm properties of acetic acid were evaluated in vitro. Pae-MBL-positive sinks were treated with 24% acetic acid once weekly and monitored with repeated cultures. FINDINGS: Fourteen patients with positive cultures for Pae-MBL were identified from 2008 to 2014. The patients had been admitted to three wards, where screening discovered Pae-MBL in 12 sink drains located in the patient bathrooms. Typing of clinical and sink drain isolates revealed identical or closely related strains. Pae-MBL biofilm was highly sensitive to acetic acid with a minimum biofilm eradication concentration of 0.75% (range: 0.19-1.5). Weekly treatment of colonized sink drains with acetic acid resulted in negative cultures and terminated transmission. CONCLUSION: Acetic acid is highly effective against Pae-MBL biofilms, and may be used as a simple method to decontaminate sink drains and to prevent nosocomial transmission.

Epidemiology of extended-spectrum ß-lactamase-producing Escherichia coli in Sweden 2007-2011.

Extended-spectrum ß-lactamase (ESBL) -producing Enterobacteriaceae have been notifiable according to the Swedish Communicable Disease Act since 2007. A major increase in the number of cases has been observed, with 2099 cases in 2007 and 7225 cases in 2012. The majority of the isolates are Escherichia coli. Additionally, Swedish data on the prevalence of ESBL-producing invasive isolates of E. coli are available through EARS-Net, and through biannual point prevalence studies, where molecular characterization of isolates from the entire country is carried out. This paper describes major trends in the Swedish epidemiology of ESBL-producing E. coli in the period 2007-2012. Isolates from the point prevalence studies were subjected to antimicrobial susceptibility testing, ESBL genotyping, pulsed-field gel electrophoresis, multi-locus sequence typing and phylogenetic grouping with PCR. The distribution of sequence types, resistance genes and susceptibility levels were all stable over the three study periods. The dominating resistance gene conferring ESBL was blaCTX -M-15 , found in 54-58% of the isolates. ST131 represented 34-38% of the isolates. Other major sequence types were ST38, ST69, ST405, ST617 and ST648, each representing 2-6% of the isolates. Phylogenetic group B2 was the most common, and was observed in 41-47% of the isolates. However, among ST131 isolates the B2 phylogenetic group represented 90-98% of the isolates. The most important epidemiological difference seen over time was that the median age of infected women decreased from 62 to 52 years (p <0.0001) and infected men from 67 to 64 years. A potential explanation might be the shift towards a higher proportion of community-acquired infections in individuals lacking comorbidities.

Characterization of plasmid-mediated AmpC-producing E. coli from Swedish broilers and association with human clinical isolates.

A selection of plasmid-mediated AmpC-producing Escherichia coli isolates carrying blaCMY-2 from Swedish broilers were characterized to establish their relatedness to and a possible overlap with human clinical E. coli isolates. The results showed diversity among the E. coli isolated from broilers, indicating that the spread in the population was not due to one strain. However, only one type of plasmid belonging to replicon type incK was identified. Furthermore, there were no indications of spread of blaCMY-2 E. coli isolates from broilers to human clinical settings, although Swedish broilers may be a source of blaCMY-2 and/or the plasmid carrying blaCMY-2 .

Multidrug-resistant, extensively drug-resistant and pandrug-resistant bacteria: an international expert proposal for interim standard definitions for acquired resistance.

Many different definitions for multidrug-resistant (MDR), extensively drug-resistant (XDR) and pandrug-resistant (PDR) bacteria are being used in the medical literature to characterize the different patterns of resistance found in healthcare-associated, antimicrobial-resistant bacteria. A group of international experts came together through a joint initiative by the European Centre for Disease Prevention and Control (ECDC) and the Centers for Disease Control and Prevention (CDC), to create a standardized international terminology with which to describe acquired resistance profiles in Staphylococcus aureus, Enterococcus spp., Enterobacteriaceae (other than Salmonella and Shigella), Pseudomonas aeruginosa and Acinetobacter spp., all bacteria often responsible for healthcare-associated infections and prone to multidrug resistance. Epidemiologically significant antimicrobial categories were constructed for each bacterium. Lists of antimicrobial categories proposed for antimicrobial susceptibility testing were created using documents and breakpoints from the Clinical Laboratory Standards Institute (CLSI), the European Committee on Antimicrobial Susceptibility Testing (EUCAST) and the United States Food and Drug Administration (FDA). MDR was defined as acquired non-susceptibility to at least one agent in three or more antimicrobial categories, XDR was defined as non-susceptibility to at least one agent in all but two or fewer antimicrobial categories (i.e. bacterial isolates remain susceptible to only one or two categories) and PDR was defined as non-susceptibility to all agents in all antimicrobial categories. To ensure correct application of these definitions, bacterial isolates should be tested against all or nearly all of the antimicrobial agents within the antimicrobial categories and selective reporting and suppression of results should be avoided.

[Epidemic strain of methicillin-resistant Staphylococcus aureus in hospitals of Saint-Petersburg].

AIM: To study genetic characteristics of methicillin-resistant Staphylococcus aureus (MRSA) causing nosocomial infections in specialized inpatient clinics of Saint-Petersburg. MATERIALS AND METHODS: Nine cultures of S. aureus, which caused nosocomial infections in patients of 3 clinics in Saint-Petersburg, were studied by pulse-electrophoresis and spa-sequence typing. Identification of superantigens' genes pvl, sea, seb, sec, tst was performed by PCR. RESULTS: Circulation of epidemic clone BT2007 attributed to spa-type t008 was revealed. According to pulse-electrotype, this epidemic clone was related with European epidemic clones of widespread cluster A. CONCLUSION: Epidemiologic surveillance for MRSA should incorporate monitoring of clonal structure of the agent on both local (intra-clinic) and regional level.

Alarming spread of vancomycin resistant enterococci in Sweden since 2007.

The total number of persons infected or colonised with vancomycin-resistant enterococci mandatorily reported to the Swedish Institute for Infectious Disease Control increased dramatically during 2007 and 2008. During a period of twenty months from 1 July 2007 to 28 February 2009, a total of 760 cases were reported compared with 194 cases reported during the entire period from 2000 to 2006. This rise was mainly attributed to a wide dissemination of vancomycin resistant enterococci which started in a number of hospitals in Stockholm in the autumn of 2007 and was followed by dissemination in various healthcare facilities (hospitals and homes for the elderly) in a further two Swedish counties in 2008. The majority of the cases (97%) were acquired in Sweden and among these, healthcare-acquired E. faecium vanB dominated (n=634). The majority of these isolates had identical or closely related pulsed-field gel electrophoresis patterns indicating clonal dissemination in the affected counties. The median minimum inhibitory concentration of vancomycin was 32 mg/L (ranging from 4 to >128 mg/L) and of teichoplanin 0.12 mg/L (ranging from 0.06 to 0.25 mg/L). Particular emphasis was placed on countermeasures such as screening, contact tracing, cleaning procedures, education in accurate use of infection control practices as well as increasing awareness of hygiene among patients and visitors. With these measures the dissemination rate decreased substantially, but new infections with the E. faecium vanB strain were still detected.

Evaluating the usefulness of spa typing, in comparison with pulsed-field gel electrophoresis, for epidemiological typing of methicillin-resistant Staphylococcus aureus in a low-prevalence region in Sweden 2000-2004.

The usefulness of spa typing was evaluated in relation to pulsed-field gel electrophoresis (PFGE), as a tool for epidemiological typing of methicillin-resistant Staphylococcus aureus (MRSA) in a low-prevalence region in southern Sweden. Bacterial isolates from 216 MRSA cases, newly identified in 2000-2004, were studied. The isolates were obtained from infected patients (31%), and from colonized individuals found by screening (69%). In total, 49 spa types and 73 PFGE patterns were identified. The discriminatory power of spa typing was lower (94.9 +/- 1.8%) than that of PFGE (97.3 +/- 1.2%). For two spa types (t002 and t008) the Panton-Valentine leukocidin results added useful discriminatory information. The most common spa types were t044 (n = 31; four PFGE patterns), t002 (n = 24; 10 PFGE patterns), t067 (n = 12; four PFGE patterns), t050 (n = 12; one PFGE pattern), and t324 (n = 11; one PFGE pattern). Epidemiological investigations identified 91 single cases and 39 transmission chains, each involving two to 13 cases. All the transmission chains were held together both by spa and PFGE typing. Among the 91 single-case isolates, 33 spa types and 50 PFGE patterns were unique (matchless) at the time of identification. The low prevalence of MRSA, the low number of outbreaks, and the wide spectrum of strains due to frequent acquisitions abroad (49% of the cases), makes spa typing a useful complement to epidemiological investigations in our setting. However, we still recommend the continued use of PFGE for further discrimination of isolates with identical spa types when epidemiological data can not exclude possible transmission.

Validity of routine surveillance data: a case study on Swedish notifications of methicillin-resistant Staphylococcus aureus.

Surveillance of communicable diseases is a public health corner stone. Routine notification data on communicable diseases are used as a basis for public health action as well as for policy making. While there are agreed standards for evaluating the performance of surveillance systems, it is rarely possible to analyse the validity of the data entered into these systems. In this study we compared data on all Swedish cases of methicillin-resistant Staphylococcus aureus (MRSA) routinely notified between 2000 and 2003 with follow-up information collected for each of these cases as part of a public health project. The variables Reason for testing (clinical sample, contact tracing, screening of risk group), Clinical presentation (disease, colonisation), Transmission setting (healthcare-acquired, community-acquired), Country of acquisition (Sweden, abroad) and Risk-occupation (yes, no) were analysed for sensitivity, positive predictive value and completeness of answers. The sensitivity varied between 23% and 83%, the positive predictive values were generally higher (55% to 97%), while missing answers varied from 11% to 59%. The proportion of community-acquired cases was markedly higher when excluding either cases of MRSA colonisation or cases found through public health-initiated activities (contact tracing or screening of risk groups). We conclude that the quality of routine surveillance data may be inadequate for in-depth epidemiological analyses. This should be taken into account when interpreting routine surveillance figures. Whether or not the case definition includes cases of MRSA colonisation may have a significant impact on population-wide estimates of MRSA occurrence.

Emergence and spread of vancomycin resistance among enterococci in Europe.

Nowadays, six types of acquired vancomycin resistance in enterococci are known; however, only VanA and to a lesser extent VanB are widely prevalent. Various genes encode acquired vancomycin resistance and these are typically associated with mobile genetic elements which allow resistance to spread clonally and laterally. The major reservoir of acquired vancomycin resistance is Enterococcus faecium; vancomycin-resistant Enterococcus faecalis are still rare. Population analysis of E. faecium has revealed a distinct subpopulation of hospital-acquired strain types, which can be differentiated by molecular typing methods (MLVA, MLST) from human commensal and animal strains. Hospital-acquired E. faecium have additional genomic content (accessory genome) including several factors known or supposed to be virulence-associated. Acquired ampicillin resistance is a major phenotypic marker of hospital-acquired E. faecium in Europe and experience has shown that it often precedes increasing rates of VRE with a delay of several years. Several factors are known to promote VRE colonisation and transmission; however, despite having populations with similar predispositions and preconditions, rates of VRE vary all over Europe.

Short summary of Swedres 2005, a report on Swedish antibiotic utilisation and resistance.

"Swedres 2005", the fifth report on Swedish antibiotic utilisation and resistance in human medicine, was presented in May 2006. Compared with the rest of Europe, antibiotic consumption and resistance levels in Sweden are relatively low. However, global travel and trade facilitate the spread of bacteria between countries and continents. As a consequence, also in Sweden, increasing resistance trends are seen for some pathogens, notably ESBL-producing enterobacteriaceae.

Staphylococcus aureus resistant to fusidic acid among Swedish children: a follow-up study.

We previously described the epidemic spread of a fusidic acid resistant clone of Staphylococcus aureus among children with bullous impetigo throughout Sweden 1. In this follow-up study we present data showing that Swedish clinicians in 2002 drastically reduced prescriptions of fusidic acid ointments, probably in response to the epidemic. Furthermore, we show that the fusidic acid resistant clone which dominated in 2001 is still the most prevalent fusidic acid resistant S. aureus in the population. The epidemic which reached its peak in 2002 is now clearly declining.

Report on the first PVL-positive community acquired MRSA strain in Latvia.

Infections by community-acquired methicillin resistant Staphylococcus aureus (CA-MRSA) have been reported worldwide. Here we present characterisation of the first CA-MRSA isolated in Latvia. A PVL-positive ST30-MRSA-IV strain was isolated from a nasal swab and the central venous catheter of a patient with fever and multiple organ failure. The PFGE pattern of this strain was identical to pattern SE00-3 of MRSA isolated in Sweden from 29 patients during 2000-2003. This strain is related to the South Pacific area, and its appearance in Sweden and Latvia demonstrates its global spread.

Penetration of fusidic acid and rifampicin into cerebrospinal fluid in low-grade inflammatory meningitis caused by Staphylococcus epidermidis.

Cerebrospinal fluid (CSF) concentration-time curves of rifampicin and fusidic acid were studied in a patient with post-operative meningitis caused by Staphylococcus epidermidis. The patient was treated with this combination of antimicrobial agents because of a severe hypersensitivity reaction to vancomycin. Peak CSF concentrations of rifampicin exceeded the MIC by > 60-fold, while those of fusidic acid just reached the MIC. CSF concentrations of fusidic acid were relatively stable within the range reported for patients with uninflamed meninges, but serum levels were surprisingly low. An increase in the metabolism of fusidic acid induced by rifampicin cannot be excluded.

Effect of clonal and serotype-specific properties on the invasive capacity of Streptococcus pneumoniae.

The present study compares the molecular epidemiology of Streptococcus pneumoniae causing invasive disease and carriage, respectively, in one geographic area (Stockholm, Sweden) during a specific point in time (the year 1997). A total of 273 invasive isolates (257 from adults and 16 from children) obtained from the 2 major hospitals in Stockholm, as well as 246 nasopharyngeal isolates recovered from children attending 16 day-care centers in the Stockholm area, were analyzed by serotyping, molecular typing (by pulsed-field gel electrophoresis and multilocus sequence typing), and antibiotic susceptibility testing. Of the 34 different serotypes plus nontypeable strains identified in the present study, 12 were never found among the 246 colonizing isolates, whereas only 3 were never found among the 273 invasive isolates. The isolates formed 2 major classes: 1 class that was found mainly among invasive isolates (type 1, 4, 7F, and 9V isolates) and was clonally highly related and 1 class that caused invasive disease but was also common in carriage (including type 6A, 6B, 14, and 19F isolates) and was genetically more diverse. Clones were found that belonged to the same serotype but had different abilities to cause invasive disease. Also, isolates belonging to the same clone were found, although they had different capsules because of serotype switch, and were found to have the same disease potential. Hence, properties associated with a particular clonal type, in addition to capsular serotype, are likely to be important for the potential of pneumococci to cause invasive disease.

Report on the first PVL-positive community acquired MRSA strain in Latvia.

Infections by community-acquired methicillin resistant Staphylococcus aureus (CA-MRSA) have been reported worldwide. Here we present characterisation of the first CA-MRSA isolated in Latvia. A PVL-positive ST30-MRSA-IV strain was isolated from a nasal swab and the central venous catheter of a patient with fever and multiple organ failure. The PFGE pattern of this strain was identical to pattern SE00-3 of MRSA isolated in Sweden from 29 patients during 2000-2003. This strain is related to the South Pacific area, and its appearance in Sweden and Latvia demonstrates its global spread.

Clonality among ampicillin-resistant Enterococcus faecium isolates in Sweden and relationship with ciprofloxacin resistance.

OBJECTIVE: To investigate clonal relationships in a nationwide sample of human Enterococcus faecium isolates. METHODS: Biochemical fingerprinting (PhP (PhenePlate) typing) was used to compare 180 fecal ampicillin-resistant E. faecium (ARE) isolates with 169 matched fecal ampicillin-susceptible E. faecium (ASE) isolates from patients in 23 hospitals, collected in 1998, and to study 39 fecal ARE isolates from non-hospitalized individuals collected in 1998, and five ARE and 29 ASE isolates from the early 1990s. Representative ARE and ASE isolates were subjected to pulsed-field gel electrophoresis (PFGE) analysis of genomic DNA and sequencing of the regions encoding the fluoroquinolone targets of the enzymes GyrA and ParC. RESULTS: Both PhP and PFGE results showed a higher homogeneity among ARE than among ASE isolates (P < 0.001). One PhP type (FMSE1) comprised 73% of the hospital ARE isolates (53% of ARE isolates from non-hospitalized individuals, and four of five ARE isolates from the early 1990s), but only 1% of the ASE isolates. PFGE of the hospital E. faecium isolates revealed that 23 of the 25 ARE isolates and one of the 22 ASE isolates were of one dominating type. High-level resistance to ciprofloxacin (MIC > 16 mg/L) was present in 91% of ARE isolates, whereas only low-level resistance (MIC 4-16 mg/L; 35% of isolates) was found among ASE isolates. One mutation in parC (codon 80) and one of two mutations in gyrA (codons 83 or 87) were detected in all ARE isolates tested with high-level ciprofloxacin resistance, but were lacking in ARE and ASE isolates with low-level ciprofloxacin resistance. CONCLUSION: Most ARE isolates in Sweden were clonally related. High-level ciprofloxacin resistance was found in ARE isolates of PhP type FMSE1 as well as in other PhP types, but never in ASE isolates.

Evaluation of a cefoxitin 30 microg disc on Iso-Sensitest agar for detection of methicillin-resistant Staphylococcus aureus.

OBJECTIVES: To evaluate the performance of a cefoxitin 30 microg disc on Iso-Sensitest agar, using a semi-confluent inoculum and overnight incubation at 35-36 degrees C, for detection of methicillin-resistant Staphylococcus aureus (MRSA). METHODS: A total of 457 S. aureus, including 190 MRSA of several defined PFGE types and a number of low-level resistant isolates, were tested with a cefoxitin 30 microg disc on Iso-Sensitest agar, using a semi-confluent inoculum and overnight incubation at 35-36 degrees C. This method was compared with the standard SRGA (Swedish Reference Group for Antibiotics) method (oxacillin 1 microg disc on Iso-Sensitest agar supplemented with 5% defibrinated horse blood, confluent growth and 24 h incubation in ambient air at 30 degrees C). RESULTS: The cefoxitin method was excellent, with a sensitivity of 100% and a specificity of 99% using an interpretative zone diameter of S > or = 29 mm and R < 29 mm. Its performance was much better than the SRGA method, which with this collection of difficult strains had a sensitivity of only 78% using the current breakpoint of S > or = 12 mm. CONCLUSION: We suggest that the cefoxitin method should replace that currently recommended by the SRGA for the detection of MRSA, and that it would fit well into BSAC methodology.

Clonal analysis of Streptococcus pneumoniae nonsusceptible to penicillin at day-care centers with index cases, in a region with low incidence of resistance: emergence of an invasive type 35B clone among carriers.

The nasopharyngeal carriage rate of potential respiratory pathogens was studied in 36 index children with a pneumococci nonsusceptible to penicillin (PNSP), in 595 healthy children, and in 123 personnel at 16 day-care centers (DCCs) with index cases in the Stockholm area, an urban area with a low incidence of antibiotic resistant pneumococci, during the winter of 1997-1998. The spread and clonality of PNSP, Haemophilus influenzae and Moraxella catarrhalis, were studied by analyzing antibiotic susceptibility and serotype, and for PSNP also by using pulsed-field electrophoresis (PFGE) and multilocus sequence typing (MLST). In contrast to the low carriage rate found among the adult contacts (2%), 40% of the children harbored pneumococci, of which 20% were PNSP. Nasopharyngeal colonization decreased with age. The 49 PNSP isolates consisted of 20 clones, of which 10 could be identified in more than one child attending the same or different DCCs. In five DCCs, we observed a spread of PNSP from the index case. A novel PNSP clone of type 35B, found to cause invasive disease in several states in the United States, was found to emerge among several carriers at two DCCs . A high proportion of PNSP isolates were multiresistant to antibiotics (34%), which has implications for treatment regimens, even in a country like Sweden where the proportion of PNSP currently is low (3-4%). One PNSP clone of type 9V found among the carriers, has been shown to cause invasive disease in Sweden as well as in other countries, suggesting that one reason for the occurrence of invasive PNSP clones may be their ability to colonize and spread among healthy carriers. Other internationally spread antibiotic resistant pneumococcal clones found were of types 9V, 19F, and 23F.