Molecular epidemiology of influenza A virus infection among hospitalized children in Vietnam during post-pandemic period.

Genetic variability makes influenza virus to escape the immunity and causes yearly epidemics. Monitoring those changes is necessary for vaccine selection. In addition, H3N2 viruses were considered to be seeded from Southeast Asia before spreading globally. This study described the molecular epidemiology of influenza A during the post-pandemic season 2010-2011 in Vietnam. Nasopharyngeal samples were collected from children with respiratory infections at Children's Hospital 2, Ho Chi Minh City. The HA, NA, M genes were amplified, sequenced and analyzed. Thirty-five of 1,082 (3.2%) patients were positive for influenza A, including 14 pandemic H1N1 2009 (H1N1pdm09) and 21 H3N2 infections. H3N2 was dominant in the rainy season (May-October 2010) while H1N1pdm09 was dominant in the dry season (November 2010-April 2011). Phylogenetic analysis showed that Vietnamese H1N1pdm09 sequences in 2010-2011 formed the distinct cluster, with other contemporary Asian and 2012-American sequences, suggesting a possible common ancestor. All were oseltamivir-sensitive except two strains carrying S247N and D199N in NA which reduced the neuraminidase inhibitor susceptibility. The Vietnamese H3N2 viruses in mid-2010 belonged to the emerging subclade Perth10/2010, which then spread worldwide in 2011. The Vietnamese influenza viruses were well matched with the Southern Hemisphere vaccine formulation. Mutations at antigenic sites were also identified in these viruses. Surveillance of influenza viruses in tropical countries is important not only for development of their prevention and control strategies but also for earlier identification of the newly emerged strains that may be selected for future vaccine.

A complex case of necrotizing pneumonia and parapneumonic effusion in a healthy 20-month-old child: Successful management with video-assisted thoracoscopic surgery and chest tube placement.

Necrotizing pneumonia (NP) is characterized by destruction of pulmonary tissue, resulting in multiple thin-walled cavities. There are limited reports on NP and parapneumonic effusion cases in children associated with Pseudomonas aeruginosa. Currently, there is no consensus regarding the optimal timing for video-assisted thoracoscopic surgery (VATS) following failure of chest tube placement and antibiotic treatment. A healthy 20-month-old child was hospitalized with symptoms of community-acquired pneumonia, progressing to severe NP and parapneumonic effusion. Despite receiving broad-spectrum antibiotics and chest tube placement on the third day of treatment, the condition continued to deteriorate, prompting VATS intervention on the sixth day. The presence of a "split pleural sign" and extensive lung necrosis on chest computed tomography contributed to initial treatment failure. Multidrug resistance P. aeruginosa was identified through nasal trachea aspiration specimens on the eighth day of treatment, leading to an adjustment in antibiotic therapy to high-dose meropenem and amikacin. Subsequently, the patient became afebrile, showed clinical improvement, and was discharged after 35 days of treatment. Through this case, we aim to emphasize an unusual pathogenic bacteria in the context of NP and the need for standardized surgical interventions in pediatric patients with NP.

Molecular epidemiology and disease severity of human respiratory syncytial virus in Vietnam.

Respiratory syncytial virus (RSV) is a major cause of acute respiratory infections (ARIs) in children worldwide and can cause high mortality, especially in developing countries. However, information on the clinical and molecular characteristics of RSV infection in developing countries is limited. From April 2010 to May 2011, 1,082 nasopharyngeal swabs were collected from children with ARI admitted to the Children's Hospital 2, Ho Chi Minh City, Vietnam. Samples were screened for RSV and genotyped by reverse transcription-PCR and sequencing. Demographic and clinical data was also recorded. RSV was found in 23.8% (257/1,082) of samples. RSV A was the dominant subgroup, accounting for 91.4% (235/257), followed by RSV B, 5.1% (13/257), and 9 cases (3.5%) were mixed infection of these subgroups. The phylogenetic analysis revealed that all group A strains belonged to the GA2 genotype. All group B strains belonged to the recently identified BA genotype, and further clustered into 2 recently described subgenotypes BA9 and BA10. One GA2 genotype strain had a premature stop codon which shortened the G protein length. RSV infection was significantly associated with younger age and higher severity score than those without. Co-infection with other viruses did not affect disease severity. RSV A caused more severe disease than RSV B. The results from this study will not only contribute to the growing database on the molecular diversity of RSV circulating worldwide but may be also useful in clinical management and vaccine development.