Navaratnam Parasakthi

Epidemiology and molecular characterization of nosocomially transmitted multidrug-resistant Klebsiella pneumoniae

OBJECTIVES To describe the epidemiology, antimicrobial susceptibility, genomic profiles, and control of a nosocomial outbreak of multidrug-resistant Klebsiella pneumoniae (MRKP) that occurred in the pediatric oncology unit of the University of Malaya Medical Centre in Kuala Lumpur. MATERIALS AND METHODS A prospective epidemiologic and microbiologic study was conducted of MRKP isolated from the blood and wound of a boy with necrotizing fasciitis after a 7-day course of ceftazidime and amikacin. In the following 2 weeks, phenotypically similar MRKP were isolated from the blood cultures of four other patients and rectal swabs of another three patients and two liquid soap samples located in the same ward. RESULTS Antimicrobial profiles demonstrated that all the isolates were resistant to ceftazidime, sensitive to imipenem and ciprofloxacin, and confirmed to be extended-spectrum beta-lactamase producers. Plasmids of varying molecular weights were present in all isolates. In eight of these isolates, which included four from blood, there were common large molecular weight plasmids ranging from 80 kb to 100 kb. Pulsed-field gel electrophoresis analysis using XbaI demonstrated six different DNA profiles, A to F. Profile A was shared by two blood culture isolates and were related by 91%. Profile B was found in one rectal swab isolate and one isolate from liquid soap and were related by 94%. Profile C was shared by one blood isolate and one liquid soap isolate and showed 100% relatedness. Profiles D, E, and F each were demonstrated by one blood isolate and two rectal swab isolates, respectively. These showed only 65% relatedness. CONCLUSIONS The MRKP strains in this outbreak were not clonal in origin. The decline of the outbreak after 4 weeks was attributed to the reemphasis of standard infection control procedures and the implementation of a program that addressed sites of environmental contamination.

Extra-intestinal non-typhoidal Salmonella infections in children

Summary Extra-intestinal non-typhoidal Salmonella (NTS) infections are uncommon in developed countries but common in developing ones. The risk factors, clinical features and outcome of children admitted to the Department of Paediatrics, University of Malaya Medical Center, Kuala Lumpur from 1978 to 1998 with extra-intestinal NTS infections were reviewed. All positive cultures of NTS, blood, cerebrospinal fluid, urine, synovial, pericardial and other body secretions (except stools), were included. Of the 98 cases reviewed, 56 were boys and 42 girls. The mean age was 2.1 years (range: newborn to 14 years). Twenty-seven children were severely immunocompromised and 21 had underlying chronic medical disorders. Bacteraemia was the most commonly detected type of infection and meningitis the commonest focal infection. The overall mortality rate was 15%. An immunocompromised state or underlying chronic medical disorder was associated with increased mortality. The three serotypes most commonly isolated were S. enteritidis, S. paratyphi B and S. typhimurium. Most isolates were sensitive to antibiotics commonly used in salmonellosis.

Seroprevalence of Helicobacter pylori infection in Malaysian children: Evidence for ethnic differences in childhood

Objectives: To determine the prevalence of Helicobacter pylor (H. pylori) in healthy Malaysian children and to discover whether differences exist among children of different races.

Penicillin susceptibility and molecular characteristics of clinical isolates of Streptococcus pneumoniae at the University of Malaya Medical Center, Kuala Lumpur, Malaysia

OBJECTIVE To determine the prevalence of penicillin resistance and molecular characteristics of pneumococcal isolates at the University of Malaya Medical Center. METHODS From March 1999 to July 2000, 100 clinical isolates of Streptococcus pneumoniae were obtained from 93 patients of various ages and from various body sites. The minimum inhibitory concentrations (MICs) for penicillin and ceftriaxone were determined by E test, and results were interpreted according to guidelines recommended by the National Committee for Clinical Laboratory Standards (NCCLS). Fifty isolates were further serotyped, and analyzed by pulsed-field gel electrophoresis (PFGE) and polymerase chain reaction/restriction fragment length polymorphism (PCR-RFLP) of the penicillin-binding protein (pbp) 2b and 2x genes. RESULTS The majority of the isolates were from respiratory sites. Thirty-one isolates showed decreased susceptibility to penicillin (PRSP), and many of these also showed decreased susceptibility to ceftriaxone. Twelve serogroup/types (SGTs) were present, with 19F being the most common. PFGE analysis identified two dominant profiles, consisting mainly of PRSPs that had common serotypes (19F) and pbp gene patterns within their respective groups, although PCR-RFLP analysis showed different patterns of pbp genes among the PRSPs as compared to penicillin-susceptible strains, which had a uniform pattern. CONCLUSION PRSPs were genetically related as shown by PFGE and serotype. The consistency of pbp gene patterns, observed among many of the PRSPs within their respective PFGE profiles, supported their relatedness as established by PFGE.

Childhood invasive pneumococcal disease: A hospital-based study from Malaysia

Aim:  New conjugate vaccine for Streptococcus pneumoniae has been introduced in Malaysia recently. Information on infection due to S. pneumoniae in Malaysian children is scarce. We conducted a retrospective chart review of childhood invasive pneumococcal disease (IPD) presented to a single centre in Malaysia.

Antimicrobial Susceptibility and Distribution of Non‐typhoidal Salmonella Serovars Isolated in Malaysian Children

There is widespread resistance of Salmonella species to commonly prescribed antimicrobials the world over. We aimed to determine the antimicrobial susceptibility and serovar distribution of non-typhoidal Salmonella (NTS) isolated from blood cultures of Malaysian children. Positive isolates of NTS from blood cultures obtained from children admitted to the pediatric wards of University of Malaya Medical Center (UMMC), a large urban hospital from Kuala Lumpur (1991-2001), and Hospital Kota Bharu (HKB), from the predominantly rural state of Kelantan (1991-1999), Malaysia, were reviewed retrospectively. Serovar distribution and antimicrobial susceptibility were ascertained. A total of 64 and 55 isolates of NTS were obtained from blood cultures of children admitted to UMMC and HKB, respectively. The commonest serovar isolated was Salmonella enteritidis in both centers. The NTS isolated were highly sensitive to the antimicrobials tested: ampicillin 98 per cent, chloramphenicol 98 per cent, gentamicin 97 per cent, trimethoprim-sulfamethoxazole (TMP-SMX) 98 per cent, and ceftriaxone 100 per cent in UMMC; ampicillin 100 per cent, chloramphenicol 87 per cent, kanamycin 100 per cent, streptomycin 96 per cent, TMP-SMX 93 per cent, and tetracycline 89 per cent in HKB. There were only one and five multi-resistant isolates in UMMC and HKB, respectively. In conclusion, NTS isolated from blood cultures of Malaysian children from Kuala Lumpur and Kota Bharu were highly sensitive to commonly prescribed antibiotics. We speculate that this is due to the restriction of sales of antimicrobials in Malaysia except by prescription. Continuing vigilance and frequent antmicrobial surveillance is necessary.

Septicaemia in paediatric cancer patients: a 5-year surveillance study in university hospital, Kuala Lumpur, Malaysia.

Infectious complications are the major cause of morbidity and mortality in children with malignancy. Empirical antimicrobial therapy in the management of fever of unknown origin should be tailored to local bacteriological data and antibiotic sensitivity patterns. Five-hundred-and-fifty-nine cases of culture-proven septicaemia occurring in pediatric cancer patients between 1990 and 1994 were retrospectively analysed and compared with a similar study done in our centre between 1976 and 1979. A wide spectrum of organisms was isolated. Staphylococcus epidermidis, Staphylococcus aureus, and Klebsiella pneumoniae were the most common and consistent bacteria isolated during the 5 year period. More than 70 per cent of the staphylococci were sensitive to methicillin and universally sensitive to vancomycin. However, a worrying trend of ceftazidime-resistance amongst gram-negative organisms was found. In these situations, the use of imipenem is recommended as resistance to this antimicrobial agent was exceedingly rare.

Rapid diagnosis of acute bacterial meningitis by coagglutination and latex agglutination

Abstract Early diagnosis and initiation of appropriate antimicrobial therapy is essential for the reduction of mortality and morbidity in acute pyogenic meningitis. The rapid diagnosis of meningitis by the detection of bacterial antigens in the cerebrospinal fluid (CSF) is now possible with the availability of commercially prepared kits. One hundred and eighty-six CSF samples were cultured for bacteria and examined for antigens of common organisms causing meningitis by a coagglutination technique (COA) and a latex agglutination test (LA). The COA had a concordance rate of 95·7% with culture while that of LA was 92·9%. The detection of Haemophilus influenzae type b antigens by both kits were in complete agreement with culture results ( 15 15 ). With Streptococcus pneumoniae antigens the COA was slightly more sensitive than the LA. With the Streptococcus group B antigen, however, both the tests proved to be oversensitive thus giving rise to false positives. Both kits failed to detect Neisseria meningitidis serogroup B exoantigens in two culture positive cases. Thus, while rapid diagnosis of acute bacterial meningitis by the detection of antigens in the CSF is extremely useful, negative results do not exclude the possibility of meningitis and positive results should be interpreted with the clinical picture and other laboratory parameters.