1.The discrimination of d-tartrate positive and d-tartrate negative S. enterica subsp. enterica serovar Paratyphi B isolated in Malaysia by phenotypic and genotypic methods
Norazah Ahmad ; Shirley Tang Gee Hoon ; Mohamed Kamel Abd Ghani ; Koh Yin Tee
The Malaysian Journal of Pathology 2012;34(1):35-39
Serotyping is not suffi cient to differentiate between Salmonella species that cause paratyphoid
fever from the strains that cause milder gastroenteritis as these organisms share the same serotype
Salmonella Paratyphi B (S. Paratyphi B). Strains causing paratyphoid fever do not ferment d-tartrate
and this key feature was used in this study to determine the prevalence of these strains among the
collection of S. Paratyphi B strains isolated from patients in Malaysia. A total of 105 isolates of S.
Paratyphi B were discriminated into d-tartrate positive (dT+) and d-tartrate negative (dT-) variants
by two lead acetate test protocols and multiplex PCR. The lead acetate test protocol 1 differed
from protocol 2 by a lower inoculum size and different incubation conditions while the multiplex
PCR utilized 2 sets of primers targeting the ATG start codon of the gene STM3356. Lead acetate
protocol 1 discriminated 97.1% of the isolates as S. Paratyphi B dT+ and 2.9% as dT- while test
protocol 2 discriminated all the isolates as S. Paratyphi B dT+. The multiplex PCR test identifi ed all
105 isolates as S. Paratyphi B dT+ strains. The concordance of the lead acetate test relative to that
of multiplex PCR was 97.7% and 100% for protocol 1 and 2 respectively. This study showed that
S. Paratyphi B dT+ is a common causative agent of gastroenteritis in Malaysia while paratyphoid
fever appears to be relatively uncommon. Multiplex PCR was shown to be a simpler, more rapid
and reliable method to discriminate S. Paratyphi B than the phenotypic lead acetate test.
2.Enteric Fever in a Tertiary Paediatric Hospital: A Retrospective Six-Year Review.
Nur Adila Ahmad HATIB ; Chia Yin CHONG ; Koh Cheng THOON ; Nancy Ws TEE ; Subramania S KRISHNAMOORTHY ; Natalie Wh TAN
Annals of the Academy of Medicine, Singapore 2016;45(7):297-302
INTRODUCTIONEnteric fever is a multisystemic infection which largely affects children. This study aimed to analyse the epidemiology, clinical presentation, treatment and outcome of paediatric enteric fever in Singapore.
MATERIALS AND METHODSA retrospective review of children diagnosed with enteric fever in a tertiary paediatric hospital in Singapore was conducted from January 2006 to January 2012. Patients with positive blood cultures for Salmonella typhi or paratyphi were identified from the microbiology laboratory information system. Data was extracted from their case records.
RESULTSOf 50 enteric fever cases, 86% were due to Salmonella typhi, with 16.3% being multidrug resistant (MDR) strains. Sixty-two percent of S. typhi isolates were of decreased ciprofloxacin susceptibility (DCS). Five cases were both MDR and DCS. The remaining 14% were Salmonella paratyphi A. There were only 3 indigenous cases. Ninety-four percent had travelled to typhoid-endemic countries, 70.2% to the Indian subcontinent and the rest to Indonesia and Malaysia. All patients infected with MDR strains had travelled to the Indian subcontinent. Anaemia was a significant finding in children with typhoid, as compared to paratyphoid fever (P = 0.04). Although all children were previously well, 14% suffered severe complications including shock, pericardial effusion and enterocolitis. None had typhoid vaccination prior to their travel to developing countries.
CONCLUSIONEnteric fever is largely an imported disease in Singapore and has contributed to significant morbidity in children. The use of typhoid vaccine, as well as education on food and water hygiene to children travelling to developing countries, needs to be emphasised.
Adolescent ; Anemia ; epidemiology ; Anti-Bacterial Agents ; therapeutic use ; Child ; Child, Preschool ; Drinking Water ; Drug Resistance, Multiple, Bacterial ; physiology ; Enterocolitis ; epidemiology ; Female ; Food Contamination ; Health Education ; Hospitals, Pediatric ; Humans ; India ; Indonesia ; Infant ; Malaysia ; Male ; Paratyphoid Fever ; drug therapy ; epidemiology ; microbiology ; Pericardial Effusion ; epidemiology ; Retrospective Studies ; Salmonella paratyphi A ; physiology ; Salmonella typhi ; physiology ; Shock ; epidemiology ; Singapore ; epidemiology ; Tertiary Care Centers ; Travel ; Typhoid Fever ; drug therapy ; epidemiology ; microbiology ; prevention & control ; Typhoid-Paratyphoid Vaccines ; therapeutic use
3.Risk Factors for Complicated Influenza A (H1N1) 2009 Disease in Children.
Chia Yin CHONG ; Natalie Wh TAN ; Anita MENON ; Koh Cheng THOON ; Nancy W S TEE ; Sheng FU
Annals of the Academy of Medicine, Singapore 2013;42(5):232-236
INTRODUCTIONSingapore had its first case of pandemic influenza A (H1N1) 2009 on 26 May 2009. As of 3 August 2009, 440 children with confirmed H1N1were admitted to KK Women's and Children's Hospital (KKH).
MATERIALS AND METHODSThis is a retrospective case control study of children admitted from 26 May 2009 to 19 July 2009 with H1N1infection. Cases and controls were first differentiated by whether they were complicated or non-complicated in nature, and subsequently analysed with regards to possible independent risk factors.
RESULTSWe analysed 143 admitted children; 48 cases and 95 controls (1: 2 ratio). Significant comorbidity was found in 20.3% (n = 29) of patients with the majority having asthma (n = 18, 12.6 %) followed by obesity (n = 7, 4.9%). Binary logistic regression analysis showed risk factors for complicated disease were comorbidity (adjusted OR 6.0, 95% CI, 2.5 to 14.6, P < 0.0001) and age <2 years (adjusted OR 9.8, 95% CI, 2.4 to 40, P = 0.001). Age less than 5 years was not found to be a risk factor.
CONCLUSIONIn the early stages of an evolving influenza epidemic when oseltamivir stocks are low, oseltamivir treatment for influenza can be streamlined and offered to those at highest risk who are under 2 years old or have significant comorbidity to prevent complicated disease.
Adolescent ; Age Factors ; Antiviral Agents ; therapeutic use ; Asthma ; complications ; Bronchitis ; complications ; Case-Control Studies ; Child ; Child, Preschool ; Cohort Studies ; Female ; Fluid Therapy ; Gastritis ; virology ; Gastroenteritis ; virology ; Humans ; Infant ; Influenza A Virus, H1N1 Subtype ; isolation & purification ; Influenza, Human ; complications ; Male ; Obesity ; complications ; Oseltamivir ; therapeutic use ; Pneumonia, Bacterial ; complications ; Retrospective Studies ; Risk Factors ; Seizures ; complications ; Singapore
4.Risk Factors for Severe Adenovirus Infection in Children during an Outbreak in Singapore.
Veena RAJKUMAR ; Cheryl S M CHIANG ; Jia Meng LOW ; Lin CUI ; Raymond T P LIN ; Nancy W S TEE ; Matthias MAIWALD ; Chia Yin CHONG ; Koh Cheng THOON ; Natalie W H TAN
Annals of the Academy of Medicine, Singapore 2015;44(2):50-59
BACKGROUNDHuman adenoviruses (HAdVs) can cause a variety of human illnesses, with associated temporal and geographic changes in disease incidence. We report the emergence of an outbreak of HAdV infections in Singapore, presumably caused by a change of the predominating type to HAdV-7. We examined the clinical features of children admitted with HAdV infection to 1 institution and the risk factors for severe infection.
MATERIALS AND METHODSThis is a retrospective case-control study of all HAdV-infected children admitted during weeks 1 to 19 in 2013, as identified from laboratory records. A descriptive retrospective analysis of epidemiology, clinical data and the outcome of these children was also performed. Patients with severe infections were defined as cases, those with non-severe infections as controls, and the 2 groups were compared to find possible independent risk factors.
RESULTSEighty-five patients with HAdV infection were studied, including 11 (12.9%) cases and 74 (87.1%) controls. Binary logistic regression showed that cases were more likely to be <2 years old (adjusted OR 10.6, 95% CI, 1.8 to 63.2) and to have significant comorbidities (adjusted OR 19.9, 95% CI, 3.4 to 116.1) compared to controls. The predominant type in 2013 was HAdV-7, which differed from 2011 and 2012, when HAdV-3 was more common. There was a trend towards pneumonia being more common in patients infected with HAdV-7 than in patients infected with other types, although this did not reach statistical significance (OR 2.8, 95% CI, 0.9 to 8.7).
CONCLUSIONThe emergence of HAdV-7 in a population where other HAdV types had circulated previously may have caused the outbreak in Singapore, and this was associated with more serious infections in children. Young age (<2 years) and significant comorbidities were associated with more severe HAdV infection.
Adenoviridae Infections ; epidemiology ; virology ; Adenoviruses, Human ; genetics ; pathogenicity ; Adolescent ; Case-Control Studies ; Child ; Child, Preschool ; Comorbidity ; Disease Outbreaks ; Female ; Humans ; Immunocompromised Host ; Infant ; Male ; Retrospective Studies ; Severity of Illness Index ; Singapore ; epidemiology
5.Granulomatous cervicofacial lymphadenitis in children: a nine-year study in Singapore.
Koh Cheng THOON ; Krishnamoorthy SUBRAMANIA ; Chia Yin CHONG ; Kenneth Tou En CHANG ; Nancy Wen Sim TEE
Singapore medical journal 2014;55(8):427-431
INTRODUCTIONGranulomatous cervicofacial lymphadenitis (GCL) is not uncommon in children. Nontuberculous mycobacteria (NTM) seem to be the predominant cause. We sought to study the clinical and microbiological profile of patients with GCL, and identify features that may impact outcome.
METHODSChildren aged < 16 years who presented to KK Women's and Children's Hospital, Singapore, between January 1998 and December 2006, and who had GCL were identified from laboratory records. Clinical and laboratory data was collected and analysed for risk factors for patients with positive lymph node cultures, and for patients with and without recurrence after treatment.
RESULTSIn all, 60 children were identified, with a median age of 56 (interquartile range [IQR] 34-101) months. Median duration of symptoms before presentation was 5 (IQR 4-8) weeks. The majority presented with single (73.3%) or unilateral (96.7%) lymphadenopathy, located in the submandibular, preauricular/parotid or infra-/post-auricular region (76.7%). Out of 51 patients, 26 (51.0%) had a tuberculin skin test reading of ≥ 10 mm. Out of 52 patients, 10 (19.2%) had positive mycobacterial cultures, which included seven isolates of NTM. Out of 34 cases, tuberculous polymerase chain reaction was positive in 11 (32.4%). With regard to recurrence after initial treatment, age < 5 years at presentation was found to be a predictor for recurrence (p = 0.008), while initial complete excision of affected nodes predicted no recurrence (p = 0.003).
CONCLUSIONIn our study, younger age was noted to be associated with a higher chance of recurrence, while complete excision of the involved node at initial presentation predicted non-recurrence.
Adolescent ; Child ; Child, Preschool ; Female ; Humans ; Infant ; Lymphadenitis ; diagnosis ; epidemiology ; microbiology ; Lymphatic Diseases ; diagnosis ; microbiology ; Male ; Mycobacterium ; Mycobacterium Infections ; diagnosis ; epidemiology ; microbiology ; Recurrence ; Retrospective Studies ; Singapore ; Treatment Outcome ; Tuberculin Test
6.Zika Virus: An Evolving Public Health Threat.
Chee Fu YUNG ; Chia Yin CHONG ; Kee Thai YEO ; Christina LIEW ; Lee Ching NG ; Natalie Wh TAN ; George Sh YEO ; Nancy Ws TEE ; Raymond Tp LIN ; Thiam Chye TAN ; Victor S RAJADURAI ; Jerry Ky CHAN ; Koh Cheng THOON
Annals of the Academy of Medicine, Singapore 2016;45(4):148-151