HIV Phylogeographic Analyses and Their Application in Prevention and Early Detection Programmes: The Case of the Tijuana-San Diego Border Region

12 years active surveillance for pediatric pleural empyema in a Mexican hospital: effectiveness of pneumococcal 13-valent conjugate vaccine, and early emergence of methicillin-resistant Staphylococcus aureus

Background:

Previous publications have proved the effectiveness of the 13-valent pneumococcal conjugate vaccine (PCV13) on pneumococcal pleural empyema (PnPE) in children, with little emergence of other pathogens. We searched the literature to establish whether PCV13 reduces PnPE, and to identify other pathogens causing pleural empyemas (PEs).

Material and methods:

From October 2005 to January 2018 (12.3 years) we performed active surveillance for all cases of PE at the General Hospital of Tijuana, Mexico. Isolates from pleural fluid (PF) were identified by conventional culture, and since 2014, polymerase chain reaction (PCR) was added for all culture-negative PFs. Streptococcus pneumoniae serotypes were detected by either Quellung reaction (Statens Serum Institute®) or PCR. Clinical, imagenological, laboratorial and microbiological evaluation was performed on each patient. Statistical analysis was purely descriptive.

Results:

A total of 64 PEs were identified (5.28/year). Median age was 51 months (1–191), hospitalization days 18 (4–35). Decortication was performed in 42%, and two children died (3.2%). Bacterial identification was obtained from 51 (80%). S. pneumoniae was the leading cause (29 = 56.8%), followed by Staphylococcus aureus (14 = 27.4%), Streptococcus pyogenes (3–5 = 9%) and others (5 = 9.8%). PCV13 was initiated in May 2012, and its impact on serotype-specific PnPE was 81% (much fewer than serotype 3) and for all PnPE 56.1%; however, for all PE −2.1% due to an increase of PE caused by S. aureus for all but one methicillin-resistant S. aureus (MRSA).

Conclusions:

Following 12.3 years of active surveillance, PCV13 has shown impact on both serotype-specific and all PnPEs; however, an increase of PEs by MRSA has emerged. Continuous surveillance is crucial to establish whether this epidemiological finding is transitory or not.

New resistance mutations to nucleoside reverse transcriptase inhibitors at codon 184 of HIV-1 reverse transcriptase (M184L and M184T)

Mutations at HIV-1 reverse transcriptase (RT) codon 184 such as M184V confer resistance to two nucleos(t)ide RT inhibitors (NRTI), lamivudine (3TC) and emtricitabine (FTC). The prevalence of mutations at HIV-1 RT codon 184 was evaluated using three independent RT sequence databases from treatment-experienced (TE) and treatment-naïve (TN) individuals. Data were collected retrospectively from three centers: one in Italy and two in France between 1997 and 2016. In order to highlight the role of these mutations in conferring drug resistance, structural and thermodynamic analyses were conducted by means of computational approaches. Among 32,440 RT sequences isolated from TE and 12,365 isolated from TN patients, the prevalence of HIV-1 RT codon 184 substitutions in each group was 31.21% and 0.72%, respectively. The mutations M184L and M184T have been observed only in TE patients. In all cases but four, M184L and M184T mutations were present during NRTI treatment. Molecular recognition studies on M184L and M184T structures showed both FTC and 3TC thermodynamic profiles unfavorable in comparison with the wild-type sequence, corroborated by molecular dynamic simulations (MDS). In this study, we highlighted two new resistance mutations in vivo for NRTI resistance. The low frequency of this pathway can be related to high impairment of replicative capacity mediated by these mutations.