Guilène Barnaud

Salmonella enteritidis : AmpC plasmid-mediated inducible β-lactamase (DHA-1) with an ampR gene from Morganella morganii

ABSTRACT DHA-1, a plasmid-mediated cephalosporinase from a single clinicalSalmonella enteritidis isolate, conferred resistance to oxyimino-cephalosporins (cefotaxime and ceftazidime) and cephamycins (cefoxitin and moxalactam), and this resistance was transferable toEscherichia coli HB101. An antagonism was observed between cefoxitin and aztreonam by the diffusion method. Transformation of the transconjugant E. coli strain with plasmid pNH5 carrying the ampD gene (whose product decreases the level of expression of ampC) resulted in an eightfold decrease in the MIC of cefoxitin. A clone with the same AmpC susceptibility pattern with antagonism was obtained, clone E. coliJM101(pSAL2-ind), and its nucleotide sequence was determined. It contained an open reading frame with 98.7% DNA sequence identity with the ampC gene of Morganella morganii. DNA sequence analysis also identified a gene upstream of ampCwhose sequence was 97% identical to the partial sequence of the ampR gene (435 bp) from M. morganii. The gene encoded a protein with an amino-terminal DNA-binding domain typical of transcriptional activators of the LysR family. Moreover, the intercistronic region between the ampC andampR genes was 98% identical to the corresponding region from M. morganii DNA. AmpR was shown to be functional by enzyme induction and a gel mobility-shift assay. An ampGgene was also detected in a Southern blot of DNA from the S. enteritidis isolate. These findings suggest that this inducible plasmid-mediated AmpC type β-lactamase, DHA-1, probably originated from M. morganii.

Levels of Vancomycin in Cerebrospinal Fluid of Adult Patients Receiving Adjunctive Corticosteroids to Treat Pneumococcal Meningitis: A Prospective Multicenter Observational Study

BACKGROUND Evidence from a recent randomized controlled trial suggests that dexamethasone as adjunct therapy in adult pneumococcal meningitis reduces mortality and neurological sequelae. However, adding dexamethasone has the potential to reduce penetration of vancomycin into the cerebrospinal fluid (CSF). We sought to determine concentrations of vancomycin in serum and CSF of patients with suspected or proven pneumococcal meningitis receiving dexamethasone to assess the penetration of vancomycin into the CSF during steroid therapy. METHODS In an observational open multicenter study, adult patients admitted to the intensive care unit because of suspected pneumococcal meningitis received recommended treatment for pneumococcal meningitis, comprising intravenous cefotaxime (200 mg per kg of body weight per day), vancomycin (administered as continuous infusion of 60 mg per kg of body weight per day after a loading dose of 15 mg per kg of body weight), and adjunctive therapy with dexamethasone (10 mg every 6 h). Vancomycin levels in CSF were measured on day 2 or day 3 of therapy and were correlated with protein levels in CSF and vancomycin levels in serum (determined at the same time as levels in CSF). RESULTS Fourteen patients were included. Thirteen had proven pneumococcal meningitis; 1 patient, initially suspected of having pneumococcal meningitis, was finally determined to have meningitis due to Neisseria meningitidis. Mean levels of vancomycin in serum and CSF were 25.2 and 7.2 mg/L, respectively, and were positively correlated (r=0.6; P=.025). A positive correlation was also found between the ratio of vancomycin in CSF to vancomycin in serum and the level of protein in CSF (r=0.66; P=.01). CONCLUSIONS Appropriate concentrations of vancomycin in CSF may be obtained even when concomitant steroids are used. Dexamethasone can, therefore, be used without fear of impeding vancomycin penetration into the CSF of patients with pneumococcal meningitis, provided that vancomycin dosage is adequate. This study is registered at http://www.ClinicalTrials.gov/ (registration number NCT00162578).

A novel integron in Salmonella enterica serovar Enteritidis, carrying the bla(DHA-1) gene and its regulator gene ampR, originated from Morganella morganii.

ABSTRACT The genetic organization of the gene coding for DHA-1 and the corresponding ampR gene was determined by PCR mapping. These genes have been mobilized from the Morganella morganii chromosome and inserted into a complexsulI-type integron, similar to In6 and In7. However, they are not themselves mobile cassettes. This integron probably includes a specific site for recombination allowing the mobilization of diverse resistance genes, as observed for blaCMY-1 andblaMOX-1.

Risks of nonsteroidal antiinflammatory drugs in undiagnosed intensive care unit pneumococcal pneumonia: younger and more severely affected patients.

PURPOSE The purpose of this study is to investigate whether exposure to nonsteroidal antiinflammatory drugs (NSAIDs) at the early stage of severe pneumococcal community-acquired pneumonia (CAP) requiring intensive care unit (ICU) admission may affect its presentation and outcome. MATERIAL AND METHODS Medical records of ICU adult patients (12-year period) with a pneumococcal CAP diagnosis were retrospectively analyzed according to previous NSAID exposure. RESULTS One hundred six confirmed pneumococcal CAP were identified, 20 received NSAIDs within 4 (2-6) days before admission. Nonsteroidal antiinflammatory drug-exposed patients were younger (43.3 vs 62.2 years; P < .0001), had less frequently at least one chronic comorbid condition (40% vs 75%; P = .003), had more often complicated pleural effusions (20% vs 2.3%; P = .01), and more frequent pleuropulmonary complications (odds ratio: 5.75 [1.97-16.76]). Nonsteroidal antiinflammatory drug patients required more often noninvasive ventilatory support (25% vs 4.6%; P = .003). Intensive care unit length of stay and mortality were similar. CONCLUSIONS We report as severe pneumococcal pneumonia in young and healthy patients exposed to NSAIDs as in older, more comorbid, and nonexposed ones. Nonsteroidal antiinflammatory drug use may mask initial symptoms and delay antimicrobial therapy, thus predisposing to worse outcomes.

Novel Plasmid-Encoded Class C β-Lactamase (MOX-2) in Klebsiella pneumoniae from Greece

ABSTRACT Klebsiella pneumoniae KOL, a clinical strain resistant to various β-lactams, was isolated from the stools of a patient from Greece. This strain harbored a new pI 9.1 plasmid-mediated AmpC β-lactamase with unusually high levels of hydrolytic activity for cefoxitin and cefotetan that we named MOX-2. Sequencing of blaMOX-2 revealed 93.2, 92.9, 92.7, and 73.1% identities with the deduced amino acid sequences of CMY-8, MOX-1, CMY-1, and the AmpC β-lactamase of Aeromonas sobria, respectively.

Five-year trends for ventilator-associated pneumonia: Correlation between microbiological findings and antimicrobial drug consumption.

The epidemiology of multidrug-resistant bacteria (MDRB) has changed significantly in European healthcare settings, with a decrease in frequency of meticillin-resistant Staphylococcus aureus and an increase in extended-spectrum β-lactamase (ESBL)-producing Enterobacteriaceae. Little is known about the effects of these changes on ventilator-associated pneumonia (VAP). A retrospective 5-year trend analysis of ICU antibiotic consumption and resistance in bacteria causing VAP was undertaken. Poisson regression analysis between complete microbiological data and antibiotic consumption was performed. In total, 252 episodes of VAP in 184 patients were identified between 2007 and 2011, from which 364 causal bacteria were isolated. Enterobacteriaceae isolation rates increased significantly over this period [from 6.64 to 10.52 isolates/1000 patient-days; P=0.006], mostly due to an increase in AmpC-producing Enterobacteriaceae (APE) (2.85-4.51 isolates/1000 patient-days; P=0.013), whereas the number of episodes due to S. aureus and Pseudomonas aeruginosa remained stable. A positive association was found between the increase in APE infections and an increase in past-year antibiotic consumption: amoxicillin/clavulanic acid (P=0.003), ceftazidime and cefepime (P=0.007), carbapenems (P=0.002), fluoroquinolones (P=0.012), macrolides (P=0.002) and imidazoles (P=0.004). No such association was found for the emergence of resistance in P. aeruginosa. These results indicate a change in the epidemiology of VAP, with Enterobacteriaceae exceeding P. aeruginosa and S. aureus. Moreover, a positive correlation was observed between antibiotic consumption and the incidence of potentially MDRB such as APE. No such correlation was found for ESBL-producing Escherichia coli and antibiotic-resistant P. aeruginosa.

Incidence and impact on clinical outcome of infections with piperacillin/tazobactam resistant Escherichia coli in ICU: A retrospective study

BackgroundEscherichia coli infections are frequent in ICU patients. The increased resistance to fluoroquinolones and amoxicillin/clavulanate of this pathogen mandates the prescription of broad-spectrum antibiotics such as piperacillin/tazobactam (PIP-TAZ) or third generation cephalosporins (3GC).MethodsTo assess incidence and impact on clinical outcome of infections with PIP-TAZ resistant E. coli in ICU patients, we conducted a retrospective cohort study with infections due to PIP-TAZ resistant (PIP-TAZ R) or to PIP-TAZ susceptible strains (PIP-TAZ S) between 1 January 2002 and 30 June 2004.ResultsOf 83 strains, 13 were PIP-TAZ R: 2 strains produced an extended-spectrum β-lactamase (2%), 11 produced a high level penicillinase (13%). Prior amoxicillin or amoxicillin/clavulanate prescription was reported in 7 cases (54%) of infections with PIP-TAZ R isolates and in 15 cases (21%) of infections with PIP-TAZ S isolates (p = 0.03). Time of onset of the infection from hospital admission was longer in case of infections with PIP-TAZ R than with PIP-TAZ S isolates (22 ± 32 vs 10 ± 21 days, p = 0.01). The overall ICU mortality rate was 38%. Mortality and length of stay in ICU were similar in case of infections with PIP-TAZ R isolates and with PIP-TAZ S isolates.ConclusionInfections with PIP-TAZ R E. coli are frequent in ICU patients. No prognostic impact of this pattern of resistance was found. Prescription of PIP-TAZ for empirical treatment of E. coli infections in ICU however exposes to inappropriate therapy.

Hypermucoviscous Klebsiella pneumoniae pneumonia: follow the string!

A 75-year-old man was admitted for a febrile dyspnea. He suffered from arterial hypertension, diabetes mellitus, and prostate cancer requiring hormonotherapy. At hospital admission, he was febrile (temperature 37.8 °C), with respiratory distress (respiratory rate 46/minute; oxygen saturation 93 % with 2 L/min oxygen), hypotensive (81/53 mmHg), and lethargic. Laboratory tests evidenced hypoxemia (PaO2 7.9 kPa under room air), acute kidney injury (urea 15.8 mmol/L, creatinine 152 μmol/L), and lactic acidosis (bicarbonates 20 mmol/L, lactic acid 10 mmol/L). The chest X-ray showed a right consolidation with bulging interlobar fissures (Fig. 1a). The patient was immediately treated with cefotaxime, fluid infusion followed by continuous catecholamine infusion, and intubated in the ICU. His condition rapidly deteriorated with multiple organ failures. He died from refractory septic shock 16 h after ICU admission despite maximal therapies. Tracheal aspirate yielded gram-negative bacilli; these grew, along with a blood culture, with hypermucoviscous Klebsiella pneumoniae (Kp), confirmed by a positive string test (Fig. 1b, and online resource 1). The bulging fissure sign is a frequent but nonspecific radiologic feature of Kp pneumonia. Virulence factor genes association contributes to the hypermucoviscous phenotype and to the marked invasiveness of such isolates [1, 2]. Such strains are usually susceptible to antibiotics, but the emergence of drug resistance is a challenge for the future.

Hypervirulent Klebsiella pneumoniae, a 5-year study in a French ICU

Purpose. Hypervirulent Klebsiella pneumoniae (hvKp) has emerged as a leading cause of severe community‐acquired pneumonia, liver abscess and disseminated infection in the Far East. Data regarding the incidence, clinical features and microbiological characteristics related to hvKp infections in the Western world are scarce. Methodology. The incidence, clinical features and microbiological characteristics of hvKp infections were investigated through a 5‐year survey conducted in a single French intensive care unit. K. pneumoniae strains were screened for hypermucoviscosity based on a string test. Multilocus sequence typing and multiplex PCR analysis targeting virulence genes were performed on string test‐positive strains. Results. Over a 53‐month period, a total of 59 infections due to K. pneumoniae were identified including 26 community‐onset infections. Twelve hvKp infections were documented, accounting for 46.1 % of community‐acquired K. pneumoniae. Community‐acquired pneumonia (n=6), aspiration pneumonia (n=4) and liver abscess (n=2) represented initial sites and mode of infection. Compared to non‐hvKp infections, patients with hvKp infections displayed higher rates of multi‐organ failure (83.3 % vs 35.7 %; P=0.04), but mortality rates were not different (50 % vs 35 %; P=0.71). Strains K1/ST23 (n=5) and K2/ST86 (n=5) predominated. All hvKp strains displayed wild‐type susceptibility. Conclusion. hvKp represent a potentially underestimated cause of fatal infections in the Western world.