Pharmacokinetic Interaction between Rifampicin and Clindamycin in Staphylococcal Osteoarticular Infections

The oral combination of clindamycin and rifampicin is relevant for the treatment of staphylococcal osteoarticular infections (SOAI). However, rifampicin induces CYP3A4, suggesting a pharmacokinetic (PK) interaction with clindamycin with unknown PK/pharmacodynamic (PD) consequences.

OBJECTIVES

To quantify clindamycin PK/PD markers before and during rifampicin co-administration in OAI.

METHODS

Patients with SOAI were included (NCT02782078). After an initial intravenous antistaphylococcal treatment, oral therapy was started with clindamycin (600 or 750 mg tid), followed by the addition of rifampicin 36 hours after. Population PK analysis was performed using the SAEM algorithm. PKPD markers were compared with and without rifampicin co-administration, each patient being his own control.

RESULTS

In 19 patients, Clindamycin Median (min-max) through concentrations were 2.7 (0.3-8.9) and <0.05 (<0.05-0.3) mg/L, before and during rifampicin administration, respectively. Rifampicin co-administration increased clindamycin clearance by a factor 16 and reduced the AUC_0-8h /MIC by a factor 15 (p<0.005). We simulated clindamycin plasma concentration for 1000 individuals, without and with rifampicin. Against a susceptible S. aureus strain with a clindamycin MIC of 0.0625 mg/L, more than 80% of individuals would reach all the proposed PKPD targets without co-administration of rifampicin, even with a low clindamycin dose. For the same strain, when rifampicin was co-administered, the probability to reach clindamycin PKPD targets dropped to 1% to have a %fT_>MIC = 100% and to 6% to achieve an AUC_0-24/MIC > 60, even with high dose of clindamycin.

CONCLUSION

Rifampicin co-administration with clindamycin has high impact on clindamycin exposure and PKPD targets in SOAI, which could result in clinical failures, even for a fully susceptible strain.

Evolution of fluoroquinolone-resistant Escherichia coli in the gut after ciprofloxacin treatment

BACKGROUND

Three healthy volunteers carried similar quinolone-resistant E. coli (QREC) (pulsed field gel electrophoresis profiles) in their gut before and after 14 days ciprofloxacin treatment. Given the intensity of the selective pressure and the mutagenic properties of quinolones, we determined whether these strains had evolved at the phenotypic and/or genomic levels.

MATERIAL AND METHODS

Commensal QREC from before day-0 (D0), and a month after 14 days of ciprofloxacin (D42) were compared in 3 volunteers. Growth experiments were performed; acetate levels, mutation frequencies, quinolone MICs and antibiotic tolerance were measured at D0 and D42. Genomes were sequenced and single nucleotide polymorphisms (SNPs) between D0 and D42 were analyzed using DiscoSNP and breseq methods. Cytoplasmic proteins were extracted, HPLC performed and proteins identified using X!tandem software; abundances were measured by mass spectrometry using the Spectral Counting (SC) and eXtraction Ion Chromatograms (XIC) integration methods.

RESULTS

No difference was found in MICs, growth characteristics, acetate concentrations, mutation frequencies, tolerance profiles, phylogroups, O-and H-types, fimH alleles and sequence types between D0 and D42. No SNP variation was evidenced between D0 and D42 isolates for 2/3 subjects; 2 SNP variations were evidenced in one. At the protein level, very few significant protein abundance differences were identified between D0 and D42.

CONCLUSION

No fitness, tolerance, metabolic or genomic evolution of commensal QREC was observed overtime, despite massive exposure to ciprofloxacin in the gut. The three strains behaved as if they had been unaffected by ciprofloxacin, suggesting that gut may act as a sanctuary where bacteria would be protected from the effect of antibiotics and survive without any detrimental effect of stress.

Mortality in Escherichia coli bloodstream infections: antibiotic resistance still does not make it

BACKGROUND

Escherichia coli bloodstream infections (BSIs) account for high mortality rates (5%-30%). Determinants of death are unclear, especially since the emergence of ESBL producers.

OBJECTIVES

To determine the relative weight of host characteristics, bacterial virulence and antibiotic resistance in the outcome of patients suffering from E. coli BSI.

METHODS

All consecutive patients suffering from E. coli BSI in seven teaching hospitals around Paris were prospectively included for 10 months. E. coli isolates were sequenced using Illumina NextSeq technology to determine the phylogroup, ST/ST complex (STc), virulence and antimicrobial resistance gene content. Risk factors associated with death at discharge or Day 28 were determined.

RESULTS

Overall, 545 patients (mean ± SD age 68.5 ± 16.5 years; 52.5% male) were included. Mean Charlson comorbidity index (CCI) was 5.6 (± 3.1); 19.6% and 12.8% presented with sepsis and septic shock, respectively. Portals of entry were mainly urinary (51.9%), digestive (41.9%) and pulmonary (3.5%); 98/545 isolates (18%) were third-generation cephalosporin resistant (3GC-R), including 86 ESBL producers. In-hospital death (or at Day 28) was 52/545 (9.5%). Factors independently associated with death were a pulmonary portal of entry [adjusted OR (aOR) 6.54, 95% CI 2.23-19.2, P = 0.0006], the iha_17 virulence gene (aOR 4.41, 95% CI 1.23-15.74, P = 0.022), the STc88 (aOR 3.62, 95% CI 1.30-10.09, P = 0.014), healthcare-associated infections (aOR 1.98, 95% CI 1.04-3.76, P = 0.036) and high CCI (aOR 1.14, 95% CI 1.04-1.26, P = 0.006), but not ESBL/3GC-R.

CONCLUSIONS

Host factors, portal of entry and bacterial characteristics remain major determinants associated with mortality in E. coli BSIs. Despite a high prevalence of ESBL producers, antibiotic resistance did not impact mortality. (ClinicalTrials.gov identifier: NCT02890901.).

Dimercaptosuccinic acid in combination with carbapenems against isogenic strains of Escherichia coli producing or not producing a metallo-β-lactamase in vitro and in murine peritonitis

BACKGROUND

Carbapenemase-producing Enterobacterales represent a major therapeutic challenge. MBLs, requiring zinc at their catalytic site, could be inhibited by meso-dimercaptosuccinic acid (DMSA), a heavy metal chelator already widely used for treating lead intoxication.

OBJECTIVES

To evaluate the activity of carbapenems alone or combined with DMSA against MBL-producing Escherichia coli in a severe murine peritonitis model.

METHODS

Isogenic strains of wild-type E. coli CFT073 producing the MBLs NDM-1, VIM-2 and IMP-1, and the control serine carbapenemases OXA-48 and KPC-3 were constructed. MIC determinations and time-kill assays were performed for imipenem, meropenem and ertapenem alone or in combination with DMSA. Infected mice were treated intraperitoneally for 24 h with imipenem, DMSA or their combination. Bacterial counts in peritoneal fluid and spleen were assessed at 24 h.

RESULTS

DMSA in combination with each carbapenem caused a significant decrease in the MICs for all MBL-producing strains, in a concentration-dependent manner, but did not provide benefit against non-MBL strains. In mice infected with the NDM-1-producing strain, the combination of imipenem and DMSA significantly reduced bacterial counts in peritoneal fluid (P = 0.0006) and spleen (P < 0.0001), as compared with imipenem alone, with no benefit against the KPC-3-producing and CFT073 strains. DMSA concentrations in plasma of mice were comparable to those obtained in humans with a standard oral dose.

CONCLUSIONS

DMSA restores the activity of carbapenems against MBL-producing strains, and its combination with carbapenems appears to be a promising strategy for the treatment of NDM-producing E. coli infections.

[Characteristics of patients admitted from emergency units in 18 internal medicine departments and organisation of these departments: A cross sectional study from SNFMI (SiFMI study group) in 2015]

INTRODUCTION

Patients admitted from emergency units represent a large portion of the population in internal medicine departments. The aim of this study is to identify characteristics of patients and organization of these departments.

METHODS

Between June 29th and July 26th 2015, voluntary internal medicine departments from the SiFMI group prospectively filled anonymized internet forms to collect data of each patients admitted in their ward from emergency units, during seven consecutive days.

RESULTS

Three hundred and sixty-five patients from emergency departments were admitted in 18 internal medicine inpatients departments, totalling 1100 beds and 33,530 annual stays, 56% of them for emergency units inpatients. Mean age was 68 years, 54% were women, mean Charlson score was 2.6 and 44% of the patients took at least three drugs. Main causes of hospitalization were infectious (29%) and neurological (17%) diseases. Mean length of stay was 9.2 days. The medical team was composed by a median value of 4,5 [2,75-6,25] senior full-time equivalents, 86% were internists. Each department except one received residents, two third of them were from general medicine.

CONCLUSION

This study highlights a high organizational variability among internal medicine departments and patients, and sets internal medicine as a specialty with a great capacity to achieve an integrative/comprehensive management of patients and to offer a comprehensive basis for physicians in training.

Activity of fosfomycin alone or combined with temocillin in vitro and in a murine model of peritonitis due to KPC-3- or OXA-48-producing Escherichia coli

Background

Alternative therapeutic regimens are urgently needed against carbapenemase-producing Enterobacteriaceae. Fosfomycin often remains active against KPC and OXA-48 producers, but emergence of resistance is a major limitation. Our aim was to determine whether the association of temocillin with fosfomycin might be useful to treat KPC- or OXA-48-producing Escherichia coli infections.

Methods

Isogenic derivatives of E. coli CFT073 with blaKPC-3- or blaOXA-48-harbouring plasmids (named CFT073-KPC-3 and CFT073-OXA-48, respectively) were used. The addition of temocillin to fosfomycin was tested using the chequerboard method and time-kill curves as well as in a fatal peritonitis murine model. Mice were treated for 24 h with fosfomycin alone or in combination with temocillin. Bacterial loads, before and after treatment, were determined in the peritoneal fluid and fosfomycin-resistant mutants were detected.

Results

Temocillin MICs were 8, 32 and 256 mg/L for CFT073 (WT), CFT073-KPC-3 and CFT073-OXA-48, respectively. Fosfomycin MIC was 0.5 mg/L for all strains. The chequerboard experiments demonstrated synergy for all three strains. In time-kill curves, combining temocillin with fosfomycin was synergistic, bactericidal and prevented emergence of resistance for CFT073-pTOPO and CFT073-KPC-3, but not CFT073-OXA-48. In vivo, for the three strains, bacterial counts were lower in peritoneal fluid with the combination compared with fosfomycin alone (P < 0.001) and inhibited growth of resistant mutants in all cases.

Conclusions

The combination of fosfomycin and temocillin demonstrated a benefit in vitro and in vivo against E. coli strains producing KPC-3 or OXA-48-type carbapenemases. This combination prevented the emergence of fosfomycin resistance and proved to be more bactericidal than fosfomycin alone.

The inoculum effect of Escherichia coli expressing mcr-1 or not on colistin activity in a murine model of peritonitis

OBJECTIVES

Colistin often remains the last resort antibiotic active against carbapenemase-producing Enterobacteriaceae. However, while in vitro inoculum effect has been reported, therapeutic relevance of this phenomenon remains questioned.

METHODS

Ten E. coli strains were used that included the wild-type CFT073 and its transconjugant CFT073-MCR-1 and eight susceptible clinical isolates. Mice with peritonitis were treated for 24 h with colistin sulfate. Bacterial loads were determined in peritoneal fluid (PF) and spleen and colistin-resistant mutants were detected.

RESULTS

MICs of colistin against the eight susceptible clinical strains and CFT073 ranged from 0.125 to 0.5 mg/L with an inoculum of 10⁵ CFU/mL and from 2 to 4 mg/L with a 10⁷ CFU/mL inoculum; 5/9 strains with an MIC of 4 mg/L were considered resistant according to EUCAST breakpoint (resistance, > 2 mg/L). When the bacterial load of wild-type CFT073 inoculated in mice increased from 10⁷ to 10⁸ CFU: i) mean log₁₀ CFU reduction generated by colistin in PF and spleen decreased from 5.8/mL and 3.1/g, respectively, (p < 0.01) to 0.9/mL and 0.8/g, respectively (NS); ii) mice survival rate decreased from 15/15 (100%) to 6/15 (40%) (p = 0.017); and iii) proportion of mice with selection of colistin-resistant mutants increased from 4/15 to 15/15 (p < 0.01). These results were comparable to those obtained when peritonitis was produced with a 10⁷ CFU bacterial load of E. coli CFT073 expressing mcr-1, for which the mean log₁₀ CFU reductions were 3.5/mL and 0.6/g in PF and spleen, respectively (NS), and survival rate was 8/15 (53%) (p < 0.01 versus survival of mice infected with wild-type CFT073).

CONCLUSIONS

Phenotypic colistin resistance in wild-type E. coli due to an increase in inoculum size had a therapeutic impact in mice with peritonitis that was comparable to that observed when the mcr-1 gene was expressed.

Lyme borreliosis and other tick-borne diseases. Guidelines from the French scientific societies (II). Biological diagnosis, treatment, persistent symptoms after documented or suspected Lyme borreliosis

The serodiagnosis of Lyme borreliosis is based on a two-tier strategy: a screening test using an immunoenzymatic technique (ELISA), followed if positive by a confirmatory test with a western blot technique for its better specificity. Lyme serology has poor sensitivity (30-40%) for erythema migrans and should not be performed. The seroconversion occurs after approximately 6 weeks, with IgG detection (sensitivity and specificity both>90%). Serological follow-up is not recommended as therapeutic success is defined by clinical criteria only. For neuroborreliosis, it is recommended to simultaneously perform ELISA tests in samples of blood and cerebrospinal fluid to test for intrathecal synthesis of Lyme antibodies. Given the continuum between early localized and disseminated borreliosis, and the efficacy of doxycycline for the treatment of neuroborreliosis, doxycycline is preferred as the first-line regimen of erythema migrans (duration, 14 days; alternative: amoxicillin) and neuroborreliosis (duration, 14 days if early, 21 days if late; alternative: ceftriaxone). Treatment of articular manifestations of Lyme borreliosis is based on doxycycline, ceftriaxone, or amoxicillin for 28 days. Patients with persistent symptoms after appropriate treatment of Lyme borreliosis should not be prescribed repeated or prolonged antibacterial treatment. Some patients present with persistent and pleomorphic symptoms after documented or suspected Lyme borreliosis. Another condition is eventually diagnosed in 80% of them.

[Insights on the management of Lyme disease]

Lyme disease is currently a hot topic in France due to a high incidence in some areas. Its clinical polymorphism can lead to misdiagnosis on one hand and to unjustified treatment on the other hand. Clinical symptoms vary considerably according to involved organs (skin, central and/or peripheral nervous system, joints, heart, eyes) and may be limited to or associated with general non-specific signs. Biological exams must be guided by clinical symptoms to help diagnosis and treatment decision according to clinical history, presentation, time of onset and duration of symptoms. However, to date, no serologic test can discriminate between past and active disease. The role of the internist is two-fold: make a diagnosis when faced with general or focal symptoms and avoid inappropriate attribution to Lyme disease of symptoms related to alternate diagnoses.

[Influenzae and pneumococcal vaccination rate in an internal medicine ward]

INTRODUCTION

Vaccination against influenza virus and Streptococcus pneumoniae is a global health priority and authorities, on the basis of recent publications, have recently updated French recommendations. The aim of this study was to describe the influenzae and pneumococcal vaccination's rate in an internal medicine ward.

MATERIAL AND METHODS

All patients consecutively hospitalized during a 10 week-period in an internal medicine ward were included. The reasons for non-vaccination and the impact of an educational program for corrective measures were reported.

RESULTS

Overall, 198 consecutive patients were included; 93 (47%) were immunocompromised; 142 (71.2%) had an indication for pneumococcal vaccination and 171 (86.4%) for influenza vaccination but only 16.2% and 55% of them were vaccinated against these microorganisms, respectively. Prior pneumococcal vaccination was more frequently observed in immunocompromised patients than in non-immunocompromised patients (21.1 versus 6.4%; P=0.029), but no significant difference was observed for influenza vaccine. Corrective measures were initiated in 46 patients (39%), non-immunized against S. pneumoniae.

CONCLUSION

These results underline the very low prevalence of pneumococcal vaccination rate in at-risk hospitalized patients, as compared with influenza, despite recent recommendations.