GCF Chan

There was a time when many of us were taking a sanguine view that infection is no longer a serious problem in our era. However, despite the improvement in personal and environmental hygiene; implementation of effective vaccination and discovery of potent anti-microbials, infection remains one of the most prevalent though not necessary dreadful form of illness among children. And at time, serious new infections emerged such as SARS or Bird flu. Furthermore, even for the erstwhile infection that we think we are familiar with, it may have different presentation or treatment response pattern at various geographic locations or time points, no matter they occur to the same ethnic group or not. The underlying causes of these differences are multiple and they can be related to environmental factors, behaviour in medical practice such as the use of antibiotics, and the types of vaccination provided, etc. This polymorphic nature of infection is high-lighted by several reports related to infectious diseases in this issue.

Human metapneumovirus (hMPV) is now found to be one of the most common viral respiratory pathogens in children since its discovery in 2001. Its clinical symptoms closely resemble that of human respiratory syncytial virus such as bronchiolitis and pneumonia in young children. The pattern of hMPV infection in Hangzhou seems to be quite similar to our local experience. It presents as either asthma exacerbation or bronchiolitis. However, majority of patients in Hangzhou were <1 year-old while our local patients were mostly older child (Pieris JS, et al. Emerg Infect Dis 2003). Another interesting difference is the pattern of seasonal variation, the peak of hMPV infection occurs in winter-spring for Hangzhou but is during spring-summer period in Hong Kong. What accounts for these differences remain to be answered by future study.

In the article related to septicaemia among children with haematological malignancies, the frequency of the various microorganisms in their patient cohort is quite similar to our local situation. Both with gram positive organisms such as coagulase negative staphylococci as the main pathogens. This is partly due to the common practice in using central venous catheter in this group of patients. However, the drug resistant pattern is quite alarming in Hangzhou with 100% of their pseudomonas resistant to meropenam. As for ceftazidime, a drug used to be very effective against pseudomonas, was found to be resistant by 100% of their pseudomonas strains! This high-lighted the importance of judiciously use of antibiotics. Stringent policy on the use of antibiotics has to be reinforced at primary health care and community levels, otherwise resistant strains can emerge very quickly. This article also reminds us that we should have adequate information related to patients from other cities within China. Awareness of the different drug resistant profile can guide us in selecting the proper antibiotics for our patients.

Then, a case of acute disseminated encephalomeningitis (ADEM) developed after an episode of streptococcal pneumoniae meningoencephalitis was reported in a 4-year-old girl. Though rare, similar complication has been previously reported and sometimes may take a milder form known as "meningitis-retention syndrome". It was unfortunate that the information on previous vaccination and the serotype of the pneumoccocus was not mentioned or identified for they can provide us further insight. From our local experience, while the overall incidence of pneumococcal infection decreased, the incidence of invasive pneumococcal infection paradoxically increased after our Government provided universal conjugated pneumococcal vaccination coverage to our young children. We also noted that most of the invasive pneumococcal infection came from serotypes that were not covered by the previous 7- or 10-valents vaccines. The clinical spectrum of invasive pneumococcal infection often takes the form of either severe pneumonia with empyema or meningoencephalitis such as in this case. Furthermore, one complication that commonly developed after invasive pneumococcal infection is haemolytic uraemic syndrome. The current 13-valents conjugated vaccine appears to cover the serotypes that usually caused the invasive pneumococcal infection locally. Our colleague has to keep track with the frequent changes in disease pattern of our known pathogens over time.

Finally, we expect while the infectious disease pathogens are under evolution and "metamorphosis" with time, we can develop newer and wiser strategy to overcome the challenge. With the specialty of immunology and infectious disease just became the first accredited paediatric subspecialty locally, we expect a more systemically trained younger generation to take up the important role of combating paediatric infectious diseases in the future. With their ingenuity and dedication, we probably can be more optimistic in the future.