In vitro activity of imipenem/relebactam against Pseudomonas aeruginosa isolates recovered from ICU patients in Spain and Portugal (SUPERIOR and STEP studies)

OBJECTIVES

To study the in vitro activity of imipenem/relebactam and comparators and the imipenem/relebactam resistance mechanisms in a Pseudomonas aeruginosa collection from Portugal (STEP, 2017-18) and Spain (SUPERIOR, 2016-17) surveillance studies.

METHODS

P. aeruginosa isolates (n = 474) were prospectively recovered from complicated urinary tract (cUTI), complicated intra-abdominal (cIAI) and lower respiratory tract (LRTI) infections in 11 Portuguese and 8 Spanish ICUs. MICs were determined (ISO broth microdilution). All imipenem/relebactam-resistant P. aeruginosa isolates (n = 30) and a subset of imipenem/relebactam-susceptible strains (n = 32) were characterized by WGS.

RESULTS

Imipenem/relebactam (93.7% susceptible), ceftazidime/avibactam (93.5% susceptible) and ceftolozane/tazobactam (93.2% susceptible) displayed comparable activity. The imipenem/relebactam resistance rate was 6.3% (Portugal 5.8%; Spain 8.9%). Relebactam restored imipenem susceptibility to 76.9% (103/134) of imipenem-resistant isolates, including MDR (82.1%; 32/39), XDR (68.8%; 53/77) and difficult-to-treat (DTR) isolates (67.2%; 45/67). Among sequenced strains, differences in population structure were detected depending on the country: clonal complex (CC)175 and CC309 in Spain and CC235, CC244, CC348 and CC253 in Portugal. Different carbapenemase gene distributions were also found: VIM-20 (n = 3), VIM-1 (n = 2), VIM-2 (n = 1) and VIM-36 (n = 1) in Spain and GES-13 (n = 13), VIM-2 (n = 3) and KPC-3 (n = 2) in Portugal. GES-13-CC235 (n = 13) and VIM type-CC175 (n = 5) associations were predominant in Portugal and Spain, respectively. Imipenem/relebactam showed activity against KPC-3 strains (2/2), but was inactive against all GES-13 producers and most of the VIM producers (8/10). Mutations in genes affecting porin inactivation, efflux pump overexpression and LPS modification might also be involved in imipenem/relebactam resistance.

CONCLUSIONS

Microbiological results reinforce imipenem/relebactam as a potential option to treat cUTI, cIAI and LRTI caused by MDR/XDR P. aeruginosa isolates, except for GES-13 and VIM producers.

Distinct epidemiology and resistance mechanisms affecting ceftolozane/tazobactam in Pseudomonas aeruginosa isolates recovered from ICU patients in Spain and Portugal depicted by WGS

Objectives

To analyse the epidemiology, the resistome and the virulome of ceftolozane/tazobactam-susceptible or -resistant Pseudomonas aeruginosa clinical isolates recovered from surveillance studies in Portugal (STEP, 2017–18) and Spain (SUPERIOR, 2016–17).

Methods

P. aeruginosa isolates were recovered from intra-abdominal, urinary tract and lower respiratory tract infections in ICU patients admitted to 11 Portuguese and 8 Spanish hospitals. MICs were determined (ISO-standard broth microdilution, EUCAST 2020 breakpoints). A subset of 28 ceftolozane/tazobactam-resistant P. aeruginosa isolates were analysed and compared with 28 ceftolozane/tazobactam-susceptible P. aeruginosa strains by WGS.

Results

Clonal complex (CC) 235 (27%) and CC175 (18%) were the most frequent, followed by CC244 (13%), CC348 (9%), CC253 (5%) and CC309 (5%). Inter-hospital clonal dissemination was observed, limited to a geographical region (CC235, CC244, CC348 and CC253 in Portugal and CC175 and CC309 in Spain). Carbapenemases were detected in 25 isolates (45%): GES-13 (13/25); VIM type (10/25) [VIM-2 (4/10), VIM-20 (3/10), VIM-1 (2/10) and VIM-36 (1/10)]; and KPC-3 (2/25). GES-13-CC235 (13/15) and VIM type-CC175 (5/10) associations were observed. Interestingly, KPC-3 and VIM-36 producers showed ceftolozane/tazobactam-susceptible phenotypes. However, ceftolozane/tazobactam resistance was significantly associated with GES-13 and VIM-type carbapenemase production. Six non-carbapenemase producers also displayed ceftolozane/tazobactam resistance, three of them showing known ceftolozane/tazobactam resistance-associated mutations in the PBP3 gene, ftsI (R504C and F533L). Overall, an extensive virulome was identified in all P. aeruginosa isolates, particularly in carbapenemase-producing strains.

Conclusions

GES-13-CC235 and VIM type-CC175 were the most frequent MDR/XDR P. aeruginosa clones causing infections in Portuguese and Spanish ICU patients, respectively. Ceftolozane/tazobactam resistance was mainly due to carbapenemase production, although mutations in PBP-encoding genes may additionally be involved.

[The Age of Multidrug Resistance: Ten Year Incidence in a Neonatal Intensive Care Unit]

INTRODUCTION

The emergence of multidrug-resistant bacteria is a medical challenge nowadays. The objective of the present study was to determine the incidence of multidrug-resistant bacteria infections in a neonatal Intensive Care unit.

MATERIAL AND METHODS

Retrospective, descriptive, incidence study of infectious episodes by multidrug-resistant bacteria from 2008 to 2017 in a differentiated perinatal support unit.

RESULTS

Sixty-four infectious episodes included (median gestational age of 28 weeks and birth weight of 885 g). The isolated bacteria were: Enterobacteriaceae (n = 46); Methicillin-resistant Staphylococcus aureus (n = 12); Acinetobacter baumannii (n = 4); Pseudomonas aeruginosa (n = 2). A risk factor was identified in 90.6% of the episodes, with emphasis on central catheter (89%) and previous antibiotic therapy (78%). The lethality rate of these infections was 10.9% (Unit mortality rate: 4.4%). The overall incidence rate was 3.2 infectious episodes/100 hospitalizations, corresponding to 1.7 episodes/1000 days of hospitalization. There were three infectious outbreaks, with an increasing impact of Enterobacteriaceae.

DISCUSSION

The reported incidence rate reflects a risk population, hospitalized in an Intensive Care unit, over a long period of time. The distribution of isolated bacteria, with Enterobacteriaceae predominance, is in accordance with the shift in multidrug resistance reported worldwide. The outbreaks point to the need of understanding risk factors and means of local dissemination. The relevance of these infections is evident in their lethality rate, which is higher compared to that of general hospital infections.

CONCLUSION

The incidence rate reflects the local dimension of the problem, representing a quality indicator which is relevant for controlling these infections.

Aggregatibacter aphrophilus aortic valve infective endocarditis

Nowadays, infective endocarditis remains a major cause of morbidity and mortality worldwide and there are concerns related to the increased number of infections associated with virulent agents and medical procedures. We present a case of a homeless man with unknown medical history, admitted for lumbar pain who became confused, hypotensive and tachycardic, evolving to severe sepsis. His initial investigation was also suggestive of acute myocardial infarction but the transthoracic echocardiogram revealed massive aortic valve vegetation with perivalvular abscess leading to severe aortic regurgitation. The patient died with the final diagnosis of infective endocarditis. Later on the blood cultures was identified Aggregatibacter aphrophilus, an HACEK group agent. This case confirms that, albeit the general favorable outcomes, there are cases of serious infections, especially if the diagnosis and treatment were late.

Molecular and epidemiologic study of Clostridium difficile reveals unusual heterogeneity in clinical strains circulating in different regions in Portugal

Clostridium difficile infection (CDI) represents a great healthcare burden in developed countries. The emergence of the epidemic PCR ribotype (RT) 027 and its acquired fluoroquinolones resistance have accentuated the need for an active surveillance of CDI. Here we report the first countrywide study of CDI in Portugal with the characterization of 498 C. difficile clinical isolates from 20 hospitals in four regions in Portugal regarding RT, virulence factors and antimicrobial susceptibility. We identified 96 RTs with marked variations between and within regions, as only six RTs appeared in all four regions. RT027 was the most frequent RT overall (18.5%) and among healthcare facility-associated isolates (19.6%), while RT014 was the most common among community-associated isolates (12%). The north showed a high RT diversity among isolates and a low moxifloxacin (MXF) resistance rate (11.9%), being the only region in which RT027 was not predominant. In contrast, the isolates from the centre presented the highest RT027 frequency, and 53.4% were resistant to MXF. Overall, MXF resistance (33.2%) was associated (p <0.001) with the presence of binary toxin genes and mutations in tcdC regardless of the RT. Both traits appeared in almost 30% of the strains. RT027 showed a reduced susceptibility to metronidazole (p <0.01), and RT126 had higher minimum inhibitory concentrations to vancomycin (p = 0.03) compared to other RTs. The present study highlights an unusual heterogeneity of RTs in Portugal, with a high frequency of hypervirulent RTs and the emergence of virulence factors in non-027 RTs, emphasizing the need for a surveillance system for CDI in Portugal.

Gastroenterite Aguda por Campylobacter Spp: Casuística de uma Urgência Pediátrica

<p><strong>Introduction:</strong> Infection by Cambylobacter occurs worldwide and represents the main cause of acute bacterial gastroenteritis within the European Union.<br /><strong>Aims:</strong> Determine the prevalence of Campylobacter in stool cultures from patients with gastroenteritis and study their microbiological, epidemiological, clinical, and therapeutic profiles, as well as associated complications.<br /><strong>Material and Methods:</strong> Review of clinical files of patients presenting to the paediatric emergency department of a general district hospital over a 30 month period with an acute gastroenteritis and a Campylobacter isolated in a stool specimen.<br /><strong>Results:</strong> Out of 216 stool cultures, 98 (45%) were positive. We identified Campylobacter in 49 (50%) cases; 30 (61%) were female. Median age was 23 months. Fourteen patients were under one year of age, 25 between one and five years old and 10 patients were over five years old. Watery diarrhea was identified in 5 (10%) patients, bloody diarrhea in 44 (90%) and mucosanguineous in 14 (29%), while 23 (47%) had fever, 14 (29%) complained of abdominal pain and 11 (22%) presented with vomiting. One patient was septic. Five patients were admitted as inpatients. Eight patients were treated with azithromycin.<br /><strong>Discussion:</strong> This is the largest published national series on gastroenteritis by Campylobacter in children and the first in the south region. Campylobacter was the main bacteria isolated. Infection was self-resolving in the majority of cases. Nevertheless, severe forms of this infection should be considered. Increased resistance to quinolones is worrisome.<br /><strong>Conclusion:</strong> Judicious use of stool cultures allows etiological identification of bacterial gastroenteritis. The increase in Campylobacter cases reinforces the need for better control of hygiene measures in handling food products.</p><p><br /><strong>Keywords:</strong> Campylobacter; Child; Gastroenteritis; Campylobacter Infections; Emergency Service, Hospital; Portugal.</p>

[Acute gastroenteritis by Cambylobacter spp: a retrospective study of a paediatric emergency department]

INTRODUCTION

Infection by Cambylobacter occurs worldwide and represents the main cause of acute bacterial gastroenteritis within the European Union.

AIMS

Determine the prevalence of Campylobacter in stool cultures from patients with gastroenteritis and study their microbiological, epidemiological, clinical, and therapeutic profiles, as well as associated complications.

MATERIAL AND METHODS

Review of clinical files of patients presenting to the paediatric emergency department of a general district hospital over a 30 month period with an acute gastroenteritis and a Campylobacter isolated in a stool specimen.

RESULTS

Out of 216 stool cultures, 98 (45%) were positive. We identified Campylobacter in 49 (50%) cases; 30 (61%) were female. Median age was 23 months. Fourteen patients were under one year of age, 25 between one and five years old and 10 patients were over five years old. Watery diarrhea was identified in 5 (10%) patients, bloody diarrhea in 44 (90%) and mucosanguineous in 14 (29%), while 23 (47%) had fever, 14 (29%) complained of abdominal pain and 11 (22%) presented with vomiting. One patient was septic. Five patients were admitted as inpatients. Eight patients were treated with azithromycin.

DISCUSSION

This is the largest published national series on gastroenteritis by Campylobacter in children and the first in the south region. Campylobacter was the main bacteria isolated. Infection was self-resolving in the majority of cases. Nevertheless, severe forms of this infection should be considered. Increased resistance to quinolones is worrisome.

CONCLUSION

Judicious use of stool cultures allows etiological identification of bacterial gastroenteritis. The increase in Campylobacter cases reinforces the need for better control of hygiene measures in handling food products.

Emergence and risk factors of β-lactamase-mediated resistance to oxyimino-β-lactams in Enterobacteriaceae isolates

We studied 193 Enterobacteriaceae isolates presenting diminished susceptibility to oxyimino-cephalosporins recovered in a Portuguese hospital (2004-2008). CTX-M-3 producers, firstly detected in Portugal, were associated with a Klebsiella pneumoniae microepidemic clone. Production of CTX-M-type enzymes (CTX-M-1/-3/-9/-14/-15/-32), age ≥65 years, and nosocomial infection were risk factors for higher nonsusceptibility to oxyimino-β-lactams. CMY-2 and DHA-1 β-lactamases were only identified in 1% of isolates.

Electrochemical degradation of sulfonated amines on SI/BDD electrodes

The electrochemical oxidation of aniline (AN) and ortanilic (OA), metanilic (MA) and sulfanilic (SA) acids was performed using as anode a boron-doped diamond (BDD) electrode. Tests were performed with model solutions of the different amines, with concentrations of 200mg L(-1), using as electrolyte 0.035 M Na2SO4, in a batch cell, with re-circulation, at different current densities (200 and 300 A m(-2)). Samples were collected at pre-selected intervals and absorbance measurements, Chemical Oxygen Demand (COD), Total Organic Carbon (TOC), Total Kjeldahl Nitrogen, Ammonia Nitrogen, Nitrates and Nitrites and HPLC analysis were performed. Results have shown a good elimination of the persistent pollutant, with COD and TOC removals always higher than, respectively: AN--91% and 90%; OA--75% and 82%; MA--88% and 87%; and SA--85% and 79%. The combustion efficiencies, calculated for the first hour of the runs, for the 300 A m(-2) assays, were the following: AN--0.93; OA--0.28; MA--0.82; and SA--0.83. For all the amines studied, after 6h degradation only oxalic and maleic acids were identified by HPLC.

Direct application of the INNO-LiPA Rif.TB line-probe assay for rapid identification of Mycobacterium tuberculosis complex strains and detection of rifampin resistance in 360 smear-positive respiratory specimens from an area of high incidence of multidrug-resistant tuberculosis

The INNO-LiPA Rif.TB assay for the identification of Mycobacterium tuberculosis complex strains and the detection of rifampin (RIF) resistance has been evaluated with 360 smear-positive respiratory specimens from an area of high incidence of multidrug-resistant tuberculosis (MDR-TB). The sensitivity when compared to conventional identification/culture methods was 82.2%, and the specificity was 66.7%; the sensitivity and specificity were 100.0% and 96.9%, respectively, for the detection of RIF resistance. This assay has the potential to provide rapid information that is essential for the effective management of MDR-TB.

Native valve endocarditis due to Pichia ohmeri

Candida species can cause clinical manifestations in various organs of the cardiovascular system, i.e., the pericardium, myocardium, and endocardium, with endocarditis being the best-known clinical entity. Endocarditis is seen primarily in intravenous drug users and in individuals with damaged native valves, especially in congenital heart disease or rheumatic valvular diseases, and in prosthetic heart valves. The authors present a case of Pichia ohmeri endocarditis in an intravenous drug user, with an unusual presentation form. This is a case of a 42-year-old man, an intravenous heroin user, who was admitted to our Vascular Surgery Department because of fever and acute serious ischemia of the left inferior limb. He presented with fever (39 degrees C), a pale and cold left limb, absence of the left popliteal pulse, and a pansystolic murmur at the cardiac apex. The transthoracic echocardiogram showed a large vegetation on the anterior leaflet of the mitral valve and severe mitral regurgitation with good left ventricular systolic function. Empirical antibiotic therapy was started. Six days after admission, embolectomy was performed with partial clinical recovery. Three blood cultures and the embolus showed a teleomorphic form of Candida guilliermondii - Pichia ohmeri. Therapy with intravenous liposomal amphotericin B, fluocitosin, imipenem, and aztreonam was started. Two weeks later, his clinical condition deteriorated with acute heart failure refractory to medical therapy, mandating mechanical ventilation and high-dose vasopressor and inotropic amine support. He underwent urgent mitral valve replacement with a biologic prosthetic valve. Rapid stabilization of the cardiac status occurred, but ischemic limb lesions required further vascular interventions.

[Chronic diarrhea as late complication of partial gastrectomy]

The authors present a clinical case of a forty-nine-year-old man admitted to hospital because of a seven month history of diarrhoea. The patient had been submitted to partial gastrectomy twenty-two years ago due to peptic ulcer. The analytic study was compatible with malabsorption syndrome. The colonoscopic and radiological studies revealed the existence of two fistulas between the gastric-stump, the small intestine and the colon. The patient was submitted to surgery with resection of the fistulas and re-gastrectomy with trunk vagotomy and Roux-en-Y reanastomosis. The follow-up twelve months after surgery showed an asymptomatic subject with weight recovery who had resumed his professional activities without limitations.

[Multicenter study of isolated micro-organisms resistant to antimicrobials in 10 Portuguese hospitals in 1994]

In 1994, Microbiology Laboratories of ten Portuguese hospitals analysed isolated microorganisms found in blood and urine samples and studied antimicrobial susceptibilities of the most frequent bacterial pathogens. From 63780 blood samples, the most frequent were Staphylococcus spp. and from 69189 urine samples significant numbers of Escherichia coli, Enterococcus spp., Pseudomonas aeruginosa and Candida spp. were isolated. Escherichia coli strains (c.7000) revealed a low percentage of resistance to antibiotics with the exceptions of ampicillin (48%) and co-trimoxazol (25%). Klebsiella pneumoniae isolates (c.2000) revealed important resistance to ampicillin (98%), cephalotin (31%), co-trimoxazol (38%) and gentamicin (28%), while values for 3rd generation cephalosporins varied among hospitals, with several strains showing phenotype of extended-spectrum beta-lactamase. A great variation in resistance values of P. aeruginosa (c.4000) was found in relation to the antibiotics as well as to the hospitals. Resistance to methicillin in S. aureus (c.6000) was high, reaching an average of 47%, and it was even higher with S. epidermidis (c.3000) and S. haemolyticus (c.650). Only vancomycin was always active against these strains. In E. faecalis (c.2500) resistance was of 2% to ampicillin, 35% to gentamicin, 45% to streptomycin and 1% to vancomycin. E. faecium isolates (c.300) showed the most worrying results with 70% resistance to ampicillin, 42% to gentamicin, 59% to streptomycin and 9% (30 strains isolated in 5 hospitals) to vancomycin. Vancomycin resistant strains were also resistant to all other antibiotics.