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Myzus persicae (Sulzer, 1776), a major crop pest worldwide, displays insecticide resistance to most molecules. The R81T substitution on the β1 subunit of nicotinic receptors of acetylcholine (nAChR) confers target site resistance to neonicotinoids and is widespread in aphid populations colonizing peach tree orchards in Southern Europe. But the impact of this resistance in the field, as well as ways to optimize its management, depends largely on the dominance level of the R81T mutation. In this study, we measured by in vitro assays the response of R81T mutation to two neonicotinoids (imidacloprid and thiacloprid) in 23 M. persicae clones with different resistance genotypes in order to assess the dominance status of this allele. In this study, all homozygous clones for the R81T mutation (genotype 81TT) showed a much higher level of resistance to both active substances than other clones. The heterozygous clones 81RT displayed a slightly higher level of resistance than wild homozygous, though resistance phenotypes against both neonicotinoids in these two genotypes were overlapping. A great variation of resistance level was found within these two latter clones’ categories. The dominance level of insecticide resistance (DLC) strongly suggested that the mutant allele 81T is semirecessive (the wild 81R allele being rather dominant) for both insecticide molecules under test. Mean DLC values were 0.316 for imidacloprid and 0.351 for thiacloprid. Cross-resistance was shown between imidacloprid and thiacloprid. This partial recessivity is valuable information to broaden the knowledge on neonicotinoid resistance, a prerequisite for devising adapted management strategies against insecticide-resistant populations of M. persicae.

In 2001, although target site resistance against pyrethroids was wide-spread in clonal populations of Myzus persicae on oilseed rape in France (kdr), target site resistance against carbamates was rare. Starting in 2005, control failure by carbamates appeared. The current study was designed to document changes in insecticide-resistant genotype frequencies in France during the last decade. Two resistant genotypes (RGs) were dominant in populations in 2009–2010: RG1 with the kdr 1014F allele (16%), RG2 with the MACE 431F allele and the atypical s-kdr 918L allele (83%). The wide-spread prevalence of RG2 suggests that a substantial shift has occurred (allele 431F in <2% individuals in 2001) presumably in response to agrichemicals. Analysis of neutral markers revealed that 2009–2010 populations were composed of two differentiated genetic pools (instead of one in 2001) and that RG2 was found in two divergent superclones of M. persicae. Possible explanations for these observed shifts in population structure and especially for the dramatic increase of the double mutant RG2 are discussed.

Concentrations of sulbactam in the CSF of 18 patients with bacterial meningitis who were undergoing treatment with intravenous (iv) ampicillin were determined. Six patients received single doses of sulbactam (1 g) and 12 patients receivedmultiple doses (four times daily) by the iv route at various intervals before lumbar punctures wereperformed to monitor their condition. Concentrations of sulbactam up to 12 µg/ml were detected in the CSF between 1 and 4 hr after dosing, the higher levels being present in the CSF of patients with the most severe meningeal inflammation. There were no significant differences in the concentrations achieved after single or multiple doses of sulbactam, and the concentrations were generally similar to the concurrent concentrations of ampicillin. It is concluded that these results as well as the antibacterial properties of sulbactam plus ampicillin support the evaluation of this combination as an alternative in the treatment of bacterial meningitis.

The aim of this double-blind, randomized, placebo-controlled, 12-week study was to assess the efficacyof rifabutin (450 or 600 mgld) in the treatment of disseminated nontuberculous mycobacterial infection in patients with AIDS. Companion drugs in both arms of the study were ethambutol, clofazimine, and isoniazid. Because of low accrual, the study was prematurely terminated when a total of 382 patients had been enrolled, of which 200 were eligible (i.e., their specimens were culturepositive for Mycobacterium avium complex [MAC] or Mycobacterium xenopi at baseline) and 102 were evaluable (i.e., they were eligible, were treated for a minimum of 6 weeks, and had at least one culture assessment after baseline). The original protocol called for a total of 220 evaluable patients. At week 12, rifabutin treatment was associated with higher, although nonsignificant, rates of bacteriologic conversion than was the placebo arm, with regard to both the eligible patients (25% vs. 18%)and the evaluable patients (45%vs. 38%).Corresponding median times to culture conversion were 42 vs. 63 days (eligible patients) and 43 vs. 69 days (evaluable patients). No significant difference was observed in clinical improvement, mortality, or toxicity between the two treatment arms. The addition of rifabutin to a triple-drug regimen may contribute to the clearance of disseminated MAC infection in patients with AIDS, without causing additional toxicity.

Multi-resistant strains of Gram-negative bacteria are rapidly emerging as a frequent cause of serious bacterial infection in the hospital environment. Effective treatment must include an antibiotic with activity against these organisms. In an open multicentre study, cefepime was evaluated as empirical therapy in 156 hospitalized patients (mean age 57 years) with serious infection of the urinary tract (n = 43), lower respiratory tract (n = 101) and skin and soft tissue (n = 12). In 18 patients, septicaemia/bacteraemia was also diagnosed. Cefepime, 2 g bd, was administered for a maximum of 16 days (mean 8). Of 98 pathogens isolated, 75 were Gram-negative and 23 were Gram-positive species. Ninety-four of the pathogens were susceptible to cefepime, including multi-resistant isolates such as Pseudomonas aeruginosa and Enterobacter cloacae. The overall clinical cure rate, excluding septicaemia/bacteraemia, was 92% (94/102); the corresponding bacterial eradication rate was 95% (52/55). In patients with septicaemia/bacteraemia, the clinical cure rate was 87% (13/15) despite eradication of 100% (11/11) of the assessable pathogens. Cefepine was well-tolerated, although 14 (9%) patients experienced local intolerance at the infusion site. Other drug-related adverse events were reported in six (4%) patients and included diarrhoea, pruritus, rash and urticaria. Cefepime is safe and effective as empirical treatment for serious infections commonly found in the hospital setting. Clinical cure and bacterial eradication can be achieved with a convenient bd dosing schedule.