Salmonella enterica serovars Panama and Arechavaleta: Risk Factors for Invasive Non-Typhoidal Salmonella Disease in Guadeloupe, French West Indies.

A retrospective study was conducted to identify the risk factors associated with Salmonella enterica bacteremia in infants and children in Guadeloupe, French West Indies. The 171 patients with S. enterica infection seen between 2010 and 2014 included 155 (90.6%) with acute gastroenteritis, of whom 42 (27.1%) had concomitant bacteremia, and 16 (9.4%) with primary bacteremia. Most cases (97.7%) were in infants and children with no underlying health condition. Two subspecies were recovered: enterica (N = 161, 94.2%) and houtenae (N = 10, 5.8%). All but one (serovar Typhi) were non-typhoidal Salmonella. The most common serovars were Panama (N = 57, 33.3% of isolates) and Arechavaleta (N = 28, 16.4%). Univariate analysis showed a strong association only between age > 6 months and infection with the Panama or Arechavaleta serovar (P = 0.002). The rate of resistance to all classes of antibiotics during the study period was low (< 15%); however, the detection of one extended-spectrum beta-lactamase-producing S. enterica strain highlights the need for continued monitoring of antimicrobial drug susceptibility. Infection with Panama (P < 0.001) or Arechavaleta (P < 0.001) serovar was significantly associated with bacteremia in a multivariate analysis. These serovars are probably poorly adapted to humans or are more virulent. A delay between onset of symptoms and hospital admission > 5 days (P = 0.01), vomiting (P = 0.001), and increased respiratory rate (P = 0.001) contributed independently to bacteremia in the multivariate analysis. Thus, if non-typhoidal infection is suspected, blood should be cultured and antibiotic treatment initiated in all patients who meet these criteria.

Evidence for a continuous drift of the HIV-1 species towards higher resistance to neutralizing antibodies over the course of the epidemic.

We compared the neutralization sensitivity of early/transmitted HIV-1 variants from patients infected by subtype B viruses at 3 periods of the epidemic (1987-1991, 1996-2000, 2006-2010). Infectious pseudotyped viruses expressing envelope glycoproteins representative of the viral quasi-species infecting each patient were tested for sensitivity to neutralization by pools of sera from HIV-1 chronically infected patients and by an updated panel of 13 human monoclonal neutralizing antibodies (HuMoNAbs). A progressive significantly enhanced resistance to neutralization was observed over calendar time, by both human sera and most of the HuMoNAbs tested (b12, VRC01, VRC03, NIH45-46(G54W), PG9, PG16, PGT121, PGT128, PGT145). Despite this evolution, a combination of two HuMoNAbs (NIH45-46(G54W) and PGT128) still would efficiently neutralize the most contemporary transmitted variants. In addition, we observed a significant reduction of the heterologous neutralizing activity of sera from individuals infected most recently (2003-2007) compared to patients infected earlier (1987-1991), suggesting that the increasing resistance of the HIV species to neutralization over time coincided with a decreased immunogenicity. These data provide evidence for an ongoing adaptation of the HIV-1 species to the humoral immunity of the human population, which may add an additional obstacle to the design of an efficient HIV-1 vaccine.