Phenotypic and molecular characterizations of carbapenem-resistant Acinetobacter baumannii isolates collected within the EURECA study

Multi-drug-resistant Acinetobacter baumannii isolates are key pathogens that contribute to the global burden of antimicrobial resistance. This study aimed to investigate the phenotypic and molecular characteristics of carbapenem-resistant A. baumannii (CRAB) isolates from the EURECA clinical trial. In total, 228 CRAB clinical strains were recovered from 29 sites in 10 European countries participating in the EURECA study between May 2016 and November 2018. All strains were reconfirmed centrally for identification and antimicrobial susceptibility testing, and were then subjected to DNA isolation and whole-genome sequencing (WGS), with analysis performed using BacPipe v.1.2.6. K and O typing was performed using KAPTIVE. Overall, 226 (99.1%) strains were confirmed as CRAB isolates. The minimum inhibitory concentration (MIC₉₀) results of imipenem and meropenem were >16 mg/L. WGS showed that the isolates mainly harboured bla_OXA-23 (n=153, 67.7%) or bla_OXA-72 (n=70, 30.1%). Four bla_OXA-72 isolates from Serbia co-harboured bla_NDM-1. An IS5 transposase family element, ISAba31, was found upstream of the bla_OXA-72 gene harboured on a small (~10-kb) pSE41030-EUR plasmid. The majority of isolates (n=178, 79.1%) belonged to international clone II. Strains belonging to the same sequence type but isolated in different countries or within the same country could be delineated in different clusters by core-genome multi-locus sequence typing (MLST). Whole-genome/core-genome MLST showed high diversity among the isolates, and the most common sequence type was ST2 (n=153, 67.7%). The EURECA A. baumannii strain collection represents a unique, diverse repository of carbapenem-resistant isolates that adds to the existing knowledge of A. baumannii epidemiology and resistance genes harboured by these strains.

Nosocomial outbreak of extended-spectrum β-lactamase-producing Enterobacter cloacae among cardiothoracic surgical patients: causes and consequences

BACKGROUND

Enterobacteriaceae are recognized as leading pathogens of healthcare-associated infections.

AIM

To report the investigation of a nosocomial outbreak of extended-spectrum β-lactamase-producing Enterobacter cloacae affecting cardiothoracic surgery patients in a Belgian academic hospital.

METHODS

Cases were defined based on epidemiological and microbiological investigations, including molecular typing using repetitive element-based polymerase chain reaction and multi-locus sequence typing. Case-control studies followed by field evaluations allowed the identification of a possible reservoir, and the retrospective assessment of human and financial consequences.

FINDINGS

Over a three-month period, 42 patients were infected or colonized by CTX-M-15-producing E. cloacae strains that belonged to the same clonal lineage. Acquisition mainly occurred in the intensive care unit (N = 23) and in the cardiothoracic surgery ward (N = 16). All but one patient had, prior to acquisition, undergone a cardiothoracic surgical procedure, monitored by the same transoesophageal echocardiography (TOE) probe in the operating room. Despite negative microbiological culture results, the exclusion of the suspected probe resulted in rapid termination of the outbreak. Overall, the outbreak was associated with a high mortality rate among infected patients (40%) as well as significant costs (€266,550).

CONCLUSION

The outbreak was indirectly shown to be associated with the contamination of a manually disinfected TOE probe used per-operatively during cardiothoracic surgery procedures, because withdrawal of the putative device led to rapid termination of the outbreak.

About three cases of ulceroglandular tularemia, is this the re-emergence of Francisella tularensis in Belgium?

Tularemia is a zoonosis caused by Francisella tularensis that can be transmitted by several ways to human being and cause different clinical manifestations. We report three clinical cases of tularemia with ulceroglandular presentation in young males acquired during outdoor activities in Southern Belgium. Confirmation of the diagnosis was established by serology. Only three cases of tularemia have been reported in Belgium between 1950 and 2012 by the National Reference Laboratory CODA-CERVA (Ref Lab CODA-CERVA) but re-emergence of tularemia is established in several European countries and F. tularensis is also well known to be present in animal reservoirs and vectors in Belgium. The diagnosis of tularemia has to be considered in case of suggestive clinical presentation associated with epidemiological risk factors.

Infection due to travel-related carbapenemase-producing Enterobacteriaceae, a largely underestimated phenomenon in Belgium

BACKGROUND

Carbapenemase-producing Enterobacteriaceae (CPE) are emerging worldwide, representing a major threat for public health. Early CPE detection is crucial in order to prevent infections and the development of reservoirs/outbreaks in hospitals. In 2008, most of the CPE strains reported in Belgium were imported from patients repatriated from abroad. Actually, this is no longer the case.

OBJECTIVES AND METHODS

A surveillance was set up in Belgian hospitals (2012) in order to explore the epidemiology and determinants of CPE, including the link with international travel/hospitalization. The present article describes travel-related CPE reported in Belgium. Different other potential sources for importation of CPE are discussed.

RESULTS

Only 12% of all CPE cases reported in Belgium (2012-2013) were travel related (with/without hospitalization). This is undoubtedly an underestimation (missing travel data: 36%), considering the increasing tourism, the immigration from endemic countries, the growing number of foreign patients using scheduled medical care in Belgium, and the medical repatriations from foreign hospitals. The free movement of persons and services (European Union) contributes to an increase in foreign healthcare workers (HCW) in Belgian hospitals. Residents from nursing homes located at the country borders can be another potential source of dissemination of CPE between countries. Moreover, the high population density in Belgium can increase the risk for CPE-dissemination. Urban areas in Belgium may cumulate these potential risk factors for import/dissemination of CPE.

CONCLUSIONS

Ideally, travel history data should be obtained from hospital hygiene teams, not from the microbiological laboratory. Patients who received medical care abroad (whatever the country) should be screened for CPE at admission.

Prevalence and distribution of beta-lactamase coding genes in third-generation cephalosporin-resistant Enterobacteriaceae from bloodstream infections in Cambodia

Resistance to third-generation cephalosporins in Gram-negative bacteria is emerging in Asia. We report the prevalence and distribution of extended-spectrum beta-lactamase (ESBL), AmpC beta-lactamase and carbapenemase-coding genes in cefotaxime-resistant Enterobacteriaceae isolates from bloodstream infections (BSI) in Cambodia. All Enterobacteriaceae isolated from BSI in adult patients at Sihanouk Hospital Centre of HOPE, Phnom Penh, Cambodia (2007–2010) were assessed. Antimicrobial susceptibility testing was carried out by disc diffusion and MicroScan according to Clinical and Laboratory Standards Institute (CLSI) guidelines. Screening for ESBL, plasmidic AmpC and carbapenemase-coding genes was performed by multiplex polymerase chain reaction (PCR) sequencing assays. Identification of the ST131 clone was performed in all CTX-M-positive Escherichia coli, using PCR targeting the papB gene. Out of 183 Enterobacteriaceae, 91 (49.7 %) isolates (84 BSI episodes) were cefotaxime-resistant: E. coli (n = 68), Klebsiella pneumoniae (n = 17) and Enterobacter spp. (n = 6). Most episodes were community-acquired (66/84; 78.3 %). ESBLs were present in 89/91 (97.8 %) cefotaxime-resistant isolates: 86 (96.6 %) were CTX-M, mainly CTX-M-15 (n = 41) and CTX-M-14 (n = 21). CTX-M of group 1 were frequently associated with TEM and/or OXA-1/30 coding genes and with phenotypic combined resistance to ciprofloxacin, sulphamethoxazole–trimethoprim and gentamicin (39/50, 78.0 %). Plasmidic AmpC (CMY-2 and DHA-1 types) were found alone (n = 2) or in combination with ESBL (n = 4). Eighteen E. coli isolates were identified as B2-ST131-O25B: 11 (61.1 %) carried CTX-M-14. No carbapenemase-coding genes were detected. ESBL among Enterobacteriaceae from BSI in Cambodia is common, mainly associated with CTX-M-15 and CTX-M-14. These findings warrant urgent action for the containment of antibiotic resistance in Cambodia.

Emergence and dissemination of multi-resistant Gram negative Enterobacteriaceae: lessons to be learnt from local and national surveillance programs in Belgium

Infections caused by multi drug resistant bacteria (MDRB) constitutes an international health care problem. Since the year 2000, a longitudinal surveillance programme (LSP) and two multicentric surveys (100 hospitals, 826 isolates) were performed to monitor the emergence of MDRB in Belgium. The implementation of a LSP detected the emergence and spread of new types of ESBLs (CTX-M), mostly among community associated E. coli in the setting of a university hospital several years before the large spread and recognition in Belgium of a pathogenic E. coli CTX-M-15 (B2-O25:H4-ST131) pandemic clone (found in extra-intestinal virulent strains). This finding supports the progressive increase in Belgium of systemic infections including UTI caused by MDRB with limited therapeutical options. The real burden of the problem remains however, difficult to estimate in the absence of any surveillance network in Belgium to monitor the epidemiology of antimicrobial resistance in the community. The current Belgian national recommendations for the detection, surveillance, prevention and control of epidemics by ESBL-producing organisms and possibly other MDRBs (eg: Carbapenemase producing Enterobacteriaceae [CPE]) must be updated taking into accounts these new elements. A global coordinated network for antimicrobial surveillance resistance gathering experts (e.g: public health epidemiologists, representative of the national reference centres of antimicrobial resistance, field experts in infection control, infectious disease specialists, other clinicians and general practitioners) must be urgently implemented, including the longitudinal analysis of resistance in different ecosystems (human, animal, water and food).

Performance of different culture methods and of a commercial molecular assay for the detection of carbapenemase-producing Enterobacteriaceae in nursing homes and rehabilitation centers

Over the last several years, carbapenemase-producing Enterobacteriaceae (CPE) have been increasingly detected not only among patients in acute care hospitals, but also in long-term care facilities. In this point prevalence survey, residents from three nursing homes and patients in one rehabilitation center were screened for asymptomatic intestinal carriage of CPE by rectal swabs. The first objective was to evaluate the hypothesis of the establishment of a CPE reservoir in a geriatric/chronic care population. Secondly, we evaluated the comparative performances of different culture methods (chromID(®) CARBA, chromID(®) OXA-48, MacConkey with temocillin/meropenem, ertapenem enrichment broth) and a commercial molecular assay (Check-Direct CPE). From the 257 included residents, only one had evidence for CPE carriage. From the rectal swabs of this resident, an OXA-48-producing Klebsiella pneumoniae could be isolated and was confirmed by a molecular assay both on the strain and on the rectal swab. The specificity of the different culture methods and Check-Direct CPE was at least 97 %. Neither enrichment broth nor prolonged incubation up to 48 h increased the yield of CPE. This point prevalence survey shows a low CPE prevalence of 0.39 %. Larger scaled studies are needed in order to confirm the role of chronic care settings as secondary CPE reservoirs and to adjust the infection control and prevention recommendations.

Enteroaggregative Shiga toxin-producing Escherichia coli of serotype O104:H4 in Belgium and Luxembourg

In 2011, a large outbreak of infections caused by Shiga toxin-producing Escherichia coli (STEC) O104:H4 occurred in Germany. This exceptionally virulent strain combined virulence factors of enteroaggregative E. coli (EAggEC) and STEC. After the outbreak only a few sporadic cases of infection with this rare serotype were reported, most of which were related to travel to the Middle East or North Africa. Here we describe two cases of enteroaggregative STEC (Agg-STEC) O104:H4 infection that occurred in Belgium in 2012 and 2013 respectively. In both cases travel in a Mediterranean country preceded the infection. The first strain was isolated from the stool of a 42-year-old woman presenting bloody diarrhoea, who had travelled to Tunisia the week before. The second case involves a 14-year-old girl who, upon her return from Turkey to Belgium, suffered from an episode of bloody diarrhoea and haemolytic uraemic syndrome. Extended typing of the isolates with pulsed field gel electrophoresis revealed that the strains were closely related, though not exactly the same as the 2011 outbreak strain. This report supports the previously made hypothesis that Agg-STEC has a human reservoir and might be imported by travellers coming from an area where the pathogen is endemic. Furthermore, it emphasizes the concern that these bacteria may cause future outbreaks as evenly virulent O104:H4 isolates seem to be widespread.

Carbapenemase-producing Enterobacteriaceae in Europe: a survey among national experts from 39 countries, February 2013

The spread of carbapenemase-producing Enterobacteriaceae (CPE) is a threat to healthcare delivery, although its extent differs substantially from country to country. In February 2013, national experts from 39 European countries were invited to self-assess the current epidemiological situation of CPE in their country. Information about national management of CPE was also reported. The results highlight the urgent need for a coordinated European effort on early diagnosis, active surveillance, and guidance on infection control measures.

Probe ligation and real-time detection of KPC, OXA-48, VIM, IMP, and NDM carbapenemase genes

The Check-MDR Carba test (Check-Points, Wageningen, Netherlands), which is based on specific molecular recognition of blaNDM, blaKPC, blaOXA-48, blaVIM, and blaIMP genes by DNA probe ligation and real-time PCR detection, was evaluated on 183 well-characterized Gram-negative rods. Representatives of the 5 gene families were accurately identified (specificities and sensitivities of 100%) within 4.5 hours. This test may be helpful to differentiate carbapenem resistance mediated by carbapenemases from those involving other mechanisms.

Epidemiological investigation of a nosocomial outbreak of multidrug-resistant Corynebacterium striatum at one Belgian university hospital

During an 8-month period, 24 Corynebacterium striatum isolates recovered from lower respiratory tract specimens of 10 hospitalized patients were characterized. The organisms were identified by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) and by 16S rRNA gene sequencing. The cluster of C. striatum exclusively affected patients who had been admitted to an intensive care unit and/or subsequently transferred to one medium-size respiratory care unit. Prolonged duration of hospitalization, advanced stage of chronic obstructive pulmonary disease, recent administration of antibiotics and exposure to an invasive diagnostic procedure were the most commonly found risk factors in these patients. Seven patients were colonized and three infected. All strains displayed a similar broad spectrum resistance to antimicrobial agents, remaining susceptible to vancomycin only. Typing analysis by MALDI-TOF MS and by semi-automated repetitive sequence-based PCR (DiversiLab typing) showed that all outbreak-associated C. striatum isolates clustered together in one single type while they differed markedly from epidemiologically unrelated C. striatum isolates. Pulsed-field gel electrophoresis (PFGE) profiles revealed three distinct PFGE types among the C. striatum isolates associated with the outbreak while all external strains except one belonged to a distinct type. We conclude that C. striatum is an opportunistic nosocomial pathogen in long-term hospitalized patients and can be at the origin of major outbreaks. The routine use of MALDI-TOF MS greatly facilitated the recognition/identification of this organism in clinical samples and this technique could also offer the potential to be used as an easy and rapid epidemiological typing tool for outbreak investigation.

Validation of carbapenemase and extended-spectrum β-lactamase multiplex endpoint PCR assays according to ISO 15189

OBJECTIVES

To validate and accredit a set of three multiplex endpoint PCR assays, targeting the most important carbapenemase and minor extended-spectrum β-lactamase (ESBL) resistance genes, according to the international ISO 15189 particular requirements for the quality and competence of medical laboratories.

METHODS

Specific primers targeting ESBLs and carbapenemases were collected from the literature or designed internally. The multiplex PCRs were validated for sensitivity, specificity, intra- and inter-run reproducibility and accuracy by means of external quality control (EQC) using a collection of 137 characterized and referenced isolates. For each multiplex PCR assay, the presence of an extraction control ruled out false-negative results due to PCR inhibition or extraction faults. Amplicons were separated by capillary electrophoresis (QIAxcel system, Qiagen). The protocols and validation files were reviewed in the setting of an external audit conducted by the Belgian organization for accreditation (BELAC).

RESULTS

Sensitivity, specificity and reproducibility for each targeted gene were 100%. All isolates from the three EQC panels were correctly identified by each PCR assay (accuracy 100%). The validation files were controlled by BELAC, and the PCR protocols were accepted as accredited according to ISO 15189.

CONCLUSIONS

Three home-made multiplex PCRs targeting the major carbapenemases and four minor class A ESBL genes encountered in Gram-negative bacteria were accredited according to the ISO 15189 standards. This validation scheme could provide a useful model for laboratories aiming to accredit their own protocols.

Clinical, virological and epidemiological assessment of 2009 influenza A (H1N1) pandemic in a Belgian university hospital

BACKGROUND

Recommendations were applied before and during the Belgian pandemic (2009) H1N1 influenza wave at a university hospital (420 beds), for optimizing isolation processes and therapeutic management of possible and confirmed infected cases.

METHODS

All patients presenting to the Emergency Department (ED) between August 1st and December 31st 2009 were screened for ILI symptoms, and were isolated for clinical assessment in case of positive screening. Patients categorized as possible influenza cases and who required hospitalization were isolated in dedicated wards. Specific diagnostic algorithms were implemented. Medical charts were retrospectively reviewed and matched with results of the microbiology laboratory. Patient's characteristics were analyzed, the contribution of laboratory diagnosis on therapy and lengh of stay (LOS) in isolation was also assessed.

RESULTS

310 patients out of 6068 had a positive screening for ILI, of these, 265 were retained as possible influenza cases and 139 required hospitalization. Twenty-eight children (8 requiring hospitalization) and 20 hospitalized adult patients had confirmed influenza infection. Five adult patients were admitted to the intensive care unit (ICU), 3 requiring extracorporeal membrane oxygenation (ECMO). There was no death related to the new influenza strain. The majority of confirmed patients were diagnosed during the Belgian epidemic wave, with a sensitivity of antigen detection of 50% in children and 35% in adults comparatively to real-time PCR (RT-PCR).

CONCLUSIONS

The impact of (2009) H1N1 pandemic influenza remained limited, except for ICU patients requiring ECMO. Implementation of screening, isolation, and virological diagnosis processes led to significant improvement of patient management.

External validation of the bacterial meningitis score in children hospitalized with meningitis

The Bacterial Meningitis Score (BMS) is considered as the rule with the highest sensitivity to safely distinguish between aseptic and bacterial meningitis (BM).

OBJECTIVE

The objective of our study was to evaluate the performance of the score and its usefulness for the clinician.

METHOD

Retrospective analysis of two Belgian academic hospitals-based cohort studies. All consecutive children aged 29 days to 18 years admitted for acute meningitis between January 1996 and December 2008 was eligible. The BMS (risk of bacterial meningitis if seizure, positive cerebrospinal fluid (CSF) Gram staining, CSF protein level (3) 80 mg/dl, CSF neutrophil count 1,000/ mm3 or blood neutrophil count > or = 10,000/mm3) was applied to all patients with meningitis defined by CSF pleocytosis > 8 WBC/mm3.

RESULTS

174 patients were included in the final analysis of whom 26 (15%) had BM. Of the 93 patients categorized as having with no risk for BM (BMS score = 0), 2 patients had BM, one of which had petechial rash (negative predictive value 97.8%). BMS had a sensitivity of 92.3%. Risk of BM was significantly related to the BMS score: 6/147 (4%) patients with BMS < or = 1 had BM compared to 20/27 (74%) patients with BMS > 1.

CONCLUSIONS

Our study reports a lower sensitivity of the BMS than observed in previous validation studies. We suggest to include the BMS in a decision tree aiming to optimize the ordering of laboratory investigations including viral and bacterial PCR testing in any child with CSF pleocytosis.

Rapid evolution and spread of carbapenemases among Enterobacteriaceae in Europe

Plasmid-acquired carbapenemases in Enterobacteriaceae, which were first discovered in Europe in the 1990s, are now increasingly being identified at an alarming rate. Although their hydrolysis spectrum may vary, they hydrolyse most β-lactams, including carbapenems. They are mostly of the KPC, VIM, NDM and OXA-48 types. Their prevalence in Europe as reported in 2011 varies significantly from high (Greece and Italy) to low (Nordic countries). The types of carbapenemase vary among countries, partially depending on the cultural/population exchange relationship between the European countries and the possible reservoirs of each carbapenemase. Carbapenemase producers are mainly identified among Klebsiella pneumoniae and Escherichia coli, and still mostly in hospital settings and rarely in the community. Although important nosocomial outbreaks with carbapenemase-producing Enterobacteriaceae have been extensively reported, many new cases are still related to importation from a foreign country. Rapid identification of colonized or infected patients and screening of carriers is possible, and will probably be effective for prevention of a scenario of endemicity, as now reported for extended-spectrum β-lactamase (mainly CTX-M) producers in all European countries.

In vitro susceptibility of multidrug-resistant Enterobacteriaceae clinical isolates to tigecycline

OBJECTIVES

To assess the in vitro susceptibility of multidrug-resistant Enterobacteriaceae (MDRE) isolates to tigecycline.

METHODS

Clinical isolates of MDRE tested in this study were obtained from 91 hospitals in Belgium during the period January 2010 to April 2010. MICs of tigecycline were determined by Vitek 2 (VTK) and by the reference broth microdilution (BMD) method, and the results were interpreted based on the 2011 MIC interpretative criteria recommended by EUCAST.

RESULTS

A total of 501 non-duplicate MDRE isolates were tested. These comprised 284 isolates of Escherichia coli [255 (89.7%) were extended-spectrum β-lactamase (ESBL)-producing isolates], 72 isolates of Klebsiella pneumoniae [53 (73.6%) were ESBL-producing isolates], 72 isolates of Enterobacter aerogenes, 33 isolates of Enterobacter cloacae, 19 isolates of Klebsiella oxytoca and 21 miscellaneous others. The MIC(90) values of tigecycline for E. coli and non-E. coli ESBL-producing Enterobacteriaceae isolates were 0.5 and 2 mg/L by BMD, and 0.5 and 8 mg/L by VTK, respectively. The highest essential and categorical agreement rates between VTK and BMD results using EUCAST breakpoints were observed in E. coli isolates (97.2%), while lower and unacceptable essential and categorical agreement rates were obtained for isolates belonging to species other than E. coli (81.1% and 59.4%, respectively).

CONCLUSIONS

VTK appears to be a suitable method for routine susceptibility testing of tigecycline only for E. coli isolates, while BMD should be preferred for other Enterobacteriaceae species isolates.

Presence of extended-spectrum beta-lactamase-producing Enterobacteriaceae in waste waters, Kinshasa, the Democratic Republic of the Congo

Extended-spectrum beta-lactamase (ESBL)-producing Enterobacteriaceae are a major public health concern. We previously demonstrated the presence of ESBL-producing Enterobacteriaceae in sachet-packaged water bags sold in Kinshasa, the Democratic Republic of the Congo. In complement to the previous study, we aimed to assess the presence of ESBL-producing Enterobacteriaceae in waste waters in Kinshasa.Enterobacteriaceae isolates recovered from environmental water samples were screened and phenotypically confirmed as ESBL-producers by disk diffusion according to Clinical and Laboratory Standards Institute (CLSI) guidelines (CLSI M100-S21). Final identification to the species level and further antimicrobial susceptibility testing were carried out with MicroScan® NBC42 panels and the identification of bla (ESBL) coding genes was performed by a commercial multiplex ligation polymerase chain reaction (PCR) microarray (Check-Points CT 101, Wageningen, the Netherlands). Overall, 194 non-duplicate Enterobacteriaceae were recovered from several sewer and river sites in nine out of 24 municipalities of Kinshasa. Fourteen isolates (7.4 %) were confirmed as ESBL-producers, the main species being Enterobacter cloacae (46.6 %) and Klebsiella pneumoniae (40.0 %). Associated resistance to both aminoglycoside and fluoroquinolone antibiotics was observed in ten isolates; the remaining isolates showed co-resistance to either fluoroquinolone (n = 3) or to aminoglycoside (n = 1) alone. All but one isolate carried bla (CTX-M) genes belonging to the CTX-M-1 group. ESBL-producing Enterobacteriaceae are increasingly being reported from various sources in the community. The present results suggest that ESBL-producing Enterobacteriaceae are widespread in the environment in the community of Kinshasa. Cities in Central Africa should be added to the map of potentially ESBL-contaminated environments and highlight the need to reinforce safe water supply and public sanitation.

Rapid emergence of carbapenemase-producing Enterobacteriaceae isolates in Belgium

We report on the evolution and epidemiology of carbapenem non-susceptible Enterobacteriaceae (CNSE) including carbapenemase-producing Enterobacteriaceae (CPE) in Belgium between January 2007 and April 2011. Significantly higher numbers of CNSE and of CPE were detected in 2010 and 2011 compared to the years 2007 to 2009. The majority of patients carrying CPE did not have history of travel abroad. The rapid emergence of autochthonous CPE strains in Belgium since 2010 warrants strengthened epidemiological surveillance at national level.

Activity of moxifloxacin against intracellular community-acquired methicillin-resistant Staphylococcus aureus: comparison with clindamycin, linezolid and co-trimoxazole and attempt at defining an intracellular susceptibility breakpoint

BACKGROUND

Co-trimoxazole, clindamycin and linezolid are used to treat community-acquired methicillin-resistant Staphylococcus aureus (CA-MRSA) infections, but little is known about intracellular activity. Moxifloxacin is active against intracellular methicillin-susceptible S. aureus (MSSA), but CA-MRSA has not been studied.

METHODS

We used 12 clinical CA-MRSA, 1 MSSA overexpressing norA and 2 hospital-acquired MRSA (moxifloxacin MICs: 0.03 to 4 mg/L). Activity was assessed in broth and after phagocytosis by THP-1 macrophages or keratinocytes {concentration-dependent experiments [24 h of incubation] to determine relative potencies [EC(50)], static concentrations [C(s)] and maximal relative efficacies [E(max) (change in log(10) cfu compared with initial inoculum)] and time-dependent experiments [0-72 h] at human C(max)}.

RESULTS

Concentration-dependent experiments: in broth, EC(50) and C(s) were correlated with the MIC for all antibiotics, but moxifloxacin achieved significantly (P < 0.01) greater killing (more negative E(max)) than the comparators; and in THP-1 cells and keratinocytes, moxifloxacin acted more slowly but still reached a near bactericidal effect (2 to 3 log(10) cfu decrease) at 24 h with unchanged EC(50) and C(s) as long as its MIC was ≤0.125 mg/L (recursive partitioning analysis). Clindamycin and linezolid were static, and co-trimoxazole was unable to suppress the intracellular growth of CA-MRSA. At human C(max) in broth, moxifloxacin killed more rapidly and more extensively (≥5 log(10) cfu decrease at 10 h) than clindamycin (4 log(10) cfu at 48 h) or co-trimoxazole and linezolid (1-2 log(10) cfu at 72 h).

CONCLUSIONS

Moxifloxacin is active against both extracellular and intracellular CA-MRSA if the MIC is low, and is more effective than clindamycin, co-trimoxazole and linezolid.

Trends in production of extended-spectrum beta-lactamases among Enterobacteriaceae of clinical interest: results of a nationwide survey in Belgian hospitals

OBJECTIVES

to assess the frequency and diversity of extended-spectrum β-lactamases (ESBLs) in Enterobacteriaceae isolates in Belgium.

METHODS

during 2006 and 2008, non-duplicate clinical isolates of Enterobacteriaceae resistant to ceftazidime and/or cefotaxime were collected in 100 Belgian hospitals. ESBL production was confirmed by phenotypic and genotypic tests. MICs of 13 antimicrobial agents were determined by Etest. ESBL-encoding genes were identified by PCR sequencing and the bla(CTX-M) environment was characterized by PCR mapping. Selected isolates were genotyped by PFGE, multilocus sequence typing analysis and phylogenetic grouping by PCR.

RESULTS

overall, 733 isolates were confirmed as ESBL producers. Carbapenems and temocillin were active against ≥ 95% of all tested isolates. Co-resistance to co-trimoxazole and to ciprofloxacin was found in almost 70% and 80% of the strains, respectively. Overall, Escherichia coli (49%), Enterobacter aerogenes (32%) and Klebsiella pneumoniae (9%) represented the most prevalent species. Isolates harboured predominantly TEM-24 (30.7%), CTX-M-15 (24.2%) and TEM-52 (12.1%). Compared with 2006, the proportion of CTX-M-type enzymes increased significantly in 2008 (54% versus 23%; P < 10(-6)), mostly linked to a rising proportion of CTX-M-15-producing E. coli. TEM-24 decreased (19% in 2008 versus 43% in 2006; P < 10(-6)) during the same period, while the prevalence of TEM-52 remained unchanged (10% in 2008 versus 14% in 2006; not significant). Over 80% of the CTX-M-15-producing E. coli isolates clustered into a single PFGE type and phylogroup B2, corresponding to the sequence type (ST) 131 clone. Intra- and inter-species gene dissemination (CTX-M-15, CTX-M-2 and CTX-M-9) and wide epidemic spread of the CTX-M-15-producing E. coli ST131 clone in several Belgian hospitals were observed.

CONCLUSIONS

the rapid emergence of multiresistant CTX-M-15-producing E. coli isolates is of major concern and highlights the need for further surveillance in Belgium.

Evaluation of a new meropenem-EDTA double-ended Etest strip for the detection of the cfiA metallo-beta-lactamase gene in clinical isolates of Bacteroides fragilis

Thirty-five Bacteroides fragilis clinical isolates with varying susceptibility to meropenem were analysed with a prototype of a double-ended Etest strip containing meropenem +/- EDTA, designed for the detection of the CfiA metallo-beta-lactamase. Phenotypic results obtained with this new Etest strip were related to the genotype and compared to the results of the Etest containing imipenem +/- EDTA. Whereas the Etest with imipenem +/- EDTA only allowed detection of isolates with high-level resistance (both MICs of imipenem and meropenem >32 mg/L), reflecting the possible underestimation of CfiA prevalence in B. fragilis, the Etest with meropenem +/- EDTA proved to be more accurate, particularly for isolates with low-level carbapenem resistance, suggesting its potential for broader detection of CfiA production.

Ecthyma gangrenosum in a non-neutropaenic, elderly patient: case report and review of the literature

Ecthyma gangrenosum is a cutaneous infection most commonly associated with Pseudomonas aeruginosa bacteraemia, but it may also be encountered after breakdown of mechanical defence barriers and local infection. The characteristic lesions of ecthyma gangrenosum are haemorrhagic blisters with surrounding erythema that rapidly evolve to necrotic ulcers. A high mortality rate is reported, especially when diagnosis is delayed and in the absence of appropriate therapy. Ecthyma gangrenosum usually occurs in critically ill and immunocompromised patients. Haematological malignancies and neutropaenia are the major risk factors, but other comorbidities (e.g. diabetes mellitus and malnutrition) have also been involved. Here, we report a case of ecthyma gangrenosum in a non-neutropaenic elderly patient with multiple comorbidities and review the literature on ecthyma gangrenosum.

Antimicrobial susceptibility of anaerobic bacteria in Belgium as determined by E-test methodology

The objective was to collect recent data on the antibiotic susceptibility of clinically significant anaerobes in Belgium. A total of 333 anaerobic clinical isolates from various body sites were prospectively collected between 2005 and 2007 at two tertiary care hospitals in Belgium. The minimal inhibitory concentrations (MICs) were determined using the E-test method for nine anti-anaerobic antibiotics. Sixty-one percent of the isolates were beta-lactamase producers, which explains the poor activity of penicillin. Amoxicillin/clavulanic acid, piperacillin/tazobactam, metronidazole and meropenem were very active against most anaerobes, but around 10% of the Bacteroides fragilis group strains were non-susceptible to the two beta-lactam/beta-lactamase inhibitors. No resistance was observed to metronidazole, while 3% of the Bacteroides spp. had decreased susceptibility to meropenem (MIC > or = 4 mg/L). Cefoxitin, clindamycin and moxifloxacin were less active, with 33%, 52% and 57% of the B. fragilis group being non-susceptible respectively. Tigecycline showed consistently good activity against most anaerobes with MIC(50) and MIC(90) of 0.25 and 2 mg/L. Metronidazole, amoxicillin/clavulanate, piperacillin/tazobactam and meropenem remain good empirical choices when anaerobes are expected in our setting. Because of the occurrence of resistance to most classes of current anti-anaerobic antibiotics, it is recommended that the antimicrobial resistance patterns be monitored regularly in order to guide empirical therapy.

Vertebral osteomyelitis with spinal epidural abscess in two patients with Bacteroides fragilis bacteraemia

We report 2 cases of vertebral osteomyelitis and contiguous epidural abscess due to Bacteroides fragilis with no concomitant or past intra-abdominal infection. Decompressive surgery with laminectomy was required for both patients due to the occurrence of neurologic deficits. Clinical recovery was achieved after 8 weeks of antibiotic therapy. It included 3 weeks of intravenous therapy with clindamycin followed by an oral regimen of clindamycin for 1 patient and oral metronidazole for the other. In both cases, magnetic resonance imaging (MRI) has proved to be essential for diagnostic. The primary source of infection remained unknown despite careful investigations.

Design and validation of a low density array (Nosochip) for the detection and identification of the main pathogenic bacteria and fungi responsible for nosocomial pneumonia

The aim of this study was to be able to amplify and to detect on one array 27 different etiologic agents found in nosocomial pneumonia, some being phylogenetically closely related and others very distant. The assay is based on the use of consensus primers combined with the identification of the resulting amplicons by hybridization on specific capture probes present on an array. Three genes were necessary in order to cover the different pathogens. We took a redundancy of at least two positive spots to confirm the identity of each species. Each probe was present in triplicate on the array. The detection limit was between 10 and 1,000 DNA copies in the assay depending on the bacteria and the probe. The assay was also specific when tested both on reference collection strains corresponding to the 27 species of interest and on 57 other bacterial species of the normal human flora. Accuracy of the assay was assessed on 200 clinical isolates and some polymorphisms were indeed observed for 5 species. Effectiveness of the assay was preliminarily validated on 25 endotracheal aspirates and sputum samples, and the results were in accordance either with the cell culture or with the sequencing. Polybacterial infections were well detected in three samples. The results show that a combination of appropriate polymerase chain reaction (PCR) and redundancy of signals on the array allows specific screening of bacteria belonging to different species and genus and even fungi. The results open the way for a possible molecular detection of bacteria in the clinical diagnostic setting.

In vitro activity of temocillin against prevalent extended-spectrum beta-lactamases producing Enterobacteriaceae from Belgian intensive care units

Temocillin is a narrow spectrum penicillin with high stability to most beta-lactamases including AmpC types and extended-spectrum types (ESBLs). We have analysed its in vitro activity against 652 clinical isolates of Enterobacteriaceae prospectively collected from patients hospitalised in intensive care units at seven different university hospitals in Belgium in 2005. Strains were screened for ESBL production using cefotaxime and ceftazidime screen agar plates and by double ESBL E-tests. The MIC of temocillin and of five comparators was determined using the E-test method. ESBLs were characterized at one central laboratory by isoelectric focusing, PCR for bla genes of the SHV, TEM, and CTX-M families, and by DNA sequencing. The prevalence of ESBL-producing Enterobacteriaceae averaged 11.8% and ranged between 3.0 and 29% in the different hospitals. Meropenem exhibited the highest in vitro activity overall (mode MIC 0.064 microg; MIC(90); 0.19 microg/ml), whereas ceftazidime (MIC(90) > 256 microg/ml) and ciprofloxacin (MIC(90) > 32 microg/ml) scored the worst. Temocillin was active against more than 90% of the isolates including most AmpC- and ESBL-producing isolates. These data indicate the well preserved activity of temocillin over the years against Enterobacteriaceae and show the wide variation in prevalence of ESBL-producing Enterobacteriaceae isolates in Belgian intensive care units. Prospective clinical studies are, however, needed to validate the usefulness of temocillin in the treatment of microbiologically documented infections caused by ESBL- and/or AmpC- overproducing nosocomial Enterobacteriaceae pathogens.

Optimal assessment of the ability of children with recurrent respiratory tract infections to produce anti-polysaccharide antibodies

Specific anti-polysaccharide antibody deficiency (SPAD) is an immune disorder. Diagnostic criteria have not yet been defined clearly. One hundred and seventy-six children evaluated for recurrent respiratory tract infections were analysed retrospectively. For each subject, specific anti-pneumococcal antibodies had been measured with two enzyme-linked immunosorbent assays (ELISAs), one overall assay (OA) using the 23-valent pneumococcal polysaccharide vaccine (23-PPSV) as detecting antigen and the other purified pneumococcal polysaccharide serotypes (serotype-specific assay, SSA) (serotypes 14, 19F and 23F). Antibody levels were measured before (n = 176) and after (n = 93) immunization with the 23-PPSV. Before immunization, low titres were found for 138 of 176 patients (78%) with OA, compared to 20 of 176 patients (11%) with the SSA. We found a significant correlation between OA and SSA results. After immunization, 88% (71 of 81) of the patients considered as responders in the OA test were also responders in the SSA; 93% (71 of 76) of the patients classified as responders according to the SSA were also responders in the OA. SPAD was diagnosed in 8% (seven of 93) of patients on the basis of the absence of response in both tests. Thus, we propose to use OA as a screening test for SPAD before 23-PPSV immunization. After immunization, SSA should be used only in case of a low response in OA. Only the absence of or a very low antibody response detected by both tests should be used as a diagnostic criterion for SPAD.