Neisseria meningitidis is one of the important cause of meningitis and has been extremely susceptible to penicillin. Nevertheless, moderately penicillin resistant strains have been reported in some parts of the world. To our knowledge, there is no such report in Malaysia. We report two clinical isolates that were found to have MICs of decreased susceptibility to penicillin by the agar dilution method.
The isolation of a penicillm. resistant strain of Streptococcus pneumoniae is being reported and indicates the need to screen pneumococcal isolates for resistance towards antibiotics.
Introduction: Streptococcus pneumoniae is an important bacterial pathogen, causing respiratory infection. Penicillin resistance in S. pneumoniae is associated with alterations in the penicillin binding proteins, while resistance to macrolides is conferred either by the modification of the ribosomal target site or efflux mechanism. This study aimed to characterize S. pneumoniae and its antibiotic resistance genes using 2 sets of multiplex PCRs. Methods: A quintuplex and triplex PCR was used to characterize the pbp1A, ermB, gyrA, ply, and the mefE genes. Fifty-eight penicillin sensitive strains (PSSP), 36 penicillin intermediate strains (PISP) and 26 penicillin resistance strains (PRSP) were used. Results: Alteration in pbp1A was only observed in PISP and PRSP strains, while PCR amplification of the ermB or mefE was observed only in strains with reduced susceptibility to erythromycin. The assay was found to be sensitive as simulated blood cultures showed the lowest level of detection to be 10cfu. Conclusions: As predicted, the assay was able to differentiate penicillin susceptible from the non-susceptible strains based on the detection of the pbp1A gene, which correlated with the MIC value of the strains.
Introduction: Streptococcus pneumoniae is an important bacterial pathogen, causing respiratory infection. Penicillin resistance in S. pneumoniae is associated with alterations in the penicillin binding proteins, while resistance to macrolides is conferred either by the modification of the ribosomal target site or efflux mechanism. This study aimed to characterize S. pneumoniae and its antibiotic resistance genes using 2 sets of multiplex PCRs. Methods: A quintuplex and triplex PCR was used to characterize the pbp1A, ermB, gyrA, ply, and the mefE genes. Fifty-eight penicillin sensitive strains (PSSP), 36 penicillin intermediate strains (PISP) and 26 penicillin resistance strains (PRSP) were used. Results: Alteration in pbp1A was only observed in PISP and PRSP strains, while PCR amplification of the ermB or mefE was observed only in strains with reduced susceptibility to erythromycin. The assay was found to be sensitive as simulated blood cultures showed the lowest level of detection to be 10cfu. Conclusions: As predicted, the assay was able to differentiate penicillin susceptible from the non-susceptible strains based on the detection of the pbp1A gene, which correlated with the MIC value of the strains.
The increasing prevalence of penicillin-resistant Streptococuus pneumoniae urges for fast and accurate susceptibility testing methods. This study evaluated the comparability of three commonly used techniques; disk diffusion, E-test and agar dilution, to detect penicillin susceptibility in clinical isolates of S. pneumoniae. Fifty pneumococcal isolates, obtained from patients at the University of Malaya Medical Centre, were selected to include both penicillin-susceptible strains and those that had decreased susceptibility (resistant and intermediate) to penicillin. The minimum inhibitory concentration (MIC) values of penicillin to serve as the reference was determined by the agar dilution method in which, based on the MIC breakpoints recommended by the National Committee for Clinical Laboratory Standards (NCCLS), 27 strains had decreased susceptibility to penicillin with 17 strains resistant and 10 intermediate. Comparing to the agar dilution method, oxacillin disk diffusion test detected all strains with decreased penicillin susceptibility as such while E-test showed a close agreement of susceptibility (92%) of the isolates to penicillin. This confirmed that oxacillin is a good screening test for S. pneumoniae isolates with decreased susceptibility to penicillin while E-test is very reliable for rapid and accurate detection of penicillin susceptibility.
Streptococcus pneumoniae (S. pneumoniae) is the most common bacterial cause of pneumonia, meningitis, and otitis media, with the highest incidence among young children and the elderly. S. pneumoniae was once routinely susceptible to penicillin, but since the mid-1980s the incidence of resistance to penicillin and other antimicrobial agents has been increasing all over the world. To optimize empirical regimens and initial therapy for S. pneumoniae infections, clinical healthcare providers must be informed about the prevalence and pattern of drug resistance among the isolates in their communities. No such data are available for the Malaysian population. Therefore, this study was designed to determine the antibiotic susceptibility pattern of S. pneumoniae among colonized pre-school children in Kota Bharu, Malaysia. Pharyngeal swabs were collected from children 1 month to 6 years of age. S. pneumoniae isolates were identified according to the standard and tested for penicillin resistance with a 1-microgram oxacillin disk by the Kirby-Bauer disk diffusion methods. Of 355 nasopharyngeal specimens obtained from kindergarten students, in-patients and pediatric clinics over a period of 1 year, S. pneumoniae was isolated from 36 (10 per cent). All isolates, except one, were susceptible to penicillin. The resistant isolates was susceptible to erythromycin, chloramphenicol and cephalosporins.
Study site: kindergarten, schools, pediatric outpatients clinics, and in-patient wards of Hospital Universiti Sains Malaysia (HUSM), Kelantan, Malaysia.
This study characterized carriage and clinical pneumococcal isolates for serotypes, penicillin susceptibility, virulence genes and restriction fragment length polymorphism (RFLP) pattern of penicillin binding protein (PBP) genes. DNA fingerprint of isolates was generated by BOX-PCR. Majority of serotypes were 23F followed by 19F, 19A and 6A. Twenty-four percent of isolates were penicillin non-susceptible (PNSP). All of the targeted virulence genes were detected in all isolates with the exception of pili; 20.6% (n=22) for PI-1 and 14.0% (n=15) for PI-2. Of the 13 isolates which carried both PI-1 and PI-2, 10 were of clinical origin. Digested pbp-DNA produced three PBP-RFLP profiles for pbp1a (A1 to A3), six profiles for pbp2b (B1 to B6) and seven for pbp2x (X1 to X7) mostly in PNSPs. Based on BOX-PCR analysis, the majority of isolates were genetically diverse with a small number of potentially related isolates carrying pili genes. No obvious genotypic association was observed pertaining to carriage and clinical origin of isolates.
BACKGROUND: Streptococcus pneumoniae is a major causative agent of severe infections, including sepsis, pneumonia, meningitis, and otitis media, that has since become a major public health concern. In this study, the serotypes distribution of pneumococcal isolates was investigated to predict the efficacy of the 7-valent pneumococcal conjugate vaccine (PCV7) among the Malaysian populations.
METHODOLOGY/PRINCIPAL FINDINGS: A total of 151 clinical isolates were serotyped using multiplex PCR assays. Out of them, there were 21.2% penicillin-resistant, 29.1% penicillin-intermediate, and 49.7% penicillin-susceptible S. pneumoniae strains. Serotypes detected among the Malaysian isolates were 1, 3, 10A, 11A/11D, 12F/12A, 14, 15A, 15B/15C, 16F, 18C/18B/18A/18F, 19A, 19F, 23F, 35B, 35F/47F, 6A/6B, 7C/7B/40, 7F/7A, 9V/9A, and 34. Serotype 19F and 23F were the two most prevalent serotypes detected. Serotypes are highly associated with invasiveness of isolates (p = 0.001) and penicillin susceptibility (p<0.001). Serotype 19F was observed to have increased resistance against penicillin while serotype 19A has high invasive tendency. Age of patients was an important factor underlying the pneumococcal serotypes (p = 0.03) and clinical sites of infections (p<0.001). High prevalence of pneumococcal isolates were detected among children <5 years old at nasopharyngeal sites while elderly adults ≥60 years old were at increased risk for pneumococcal bacteremia.
CONCLUSION/SIGNIFICANCE: Current study revealed that a number of serotypes, especially those associated with high penicillin resistance, have been formulated in the PCV7. Therefore, the protections expected from the routine use of PCV7 would be encouraging for the Malaysian. However, it is not possible to predict serotypes that might become predominant in the future and hence continued surveillance of circulating serotypes will be needed.
In our previous studies, we generated a short 13 amino acid antimicrobial peptide (AMP), DM3, showing potent antipneumococcal activity in vitro and in vivo. Here we analyse the underlying mechanisms of action using Next-Generation transcriptome sequencing of penicillin (PEN)-resistant and PEN-susceptible pneumococci treated with DM3, PEN, and combination of DM3 and PEN (DM3PEN). DM3 induced differential expression in cell wall and cell membrane structural and transmembrane processes. Notably, DM3 altered the expression of competence-induction pathways by upregulating CelA, CelB, and CglA while downregulating Ccs16, ComF, and Ccs4 proteins. Capsular polysaccharide subunits were downregulated in DM3-treated cells, however, it was upregulated in PEN- and DM3PEN-treated groups. Additionally, DM3 altered the amino acids biosynthesis pathways, particularly targeting ribosomal rRNA subunits. Downregulation of cationic AMPs resistance pathway suggests that DM3 treatment could autoenhance pneumococci susceptibility to DM3. Gene enrichment analysis showed that unlike PEN and DM3PEN, DM3 treatment exerted no effect on DNA-binding RNA polymerase activity but observed downregulation of RpoD and RNA polymerase sigma factor. In contrast to DM3, DM3PEN altered the regulation of multiple purine/pyrimidine biosynthesis and metabolic pathways. Future studies based on in vitro experiments are proposed to investigate the key pathways leading to pneumococcal cell death caused by DM3.
170 clinical isolates of Pseudomonas aeruginosa were tested for in vitro susceptibility to gentamicin, amikacin, tobramycin, netilmicin, kanamycin, streptomycin, cefotaxime, ceftriaxone, cefoperazone, ceftazidime, moxalactam, azlocillin, piperacillin and ticarcillin. Against 93 gentamicin-sensitive strains, the most active antibiotics were in descending order, ceftazidime, tobramycin, gentamicin, amikacin, and the ureidopenicillins. Against 77 gentamicin-resistant strains, only ceftazidime, amikacin and moxalactam had mode minimum inhibitory concentrations within achievable peak serum levels after standard therapeutic dosage. There was no correlation between cephalosporin resistance and aminoglycoside resistance except for cefoperazone, which, together with the ureidopenicillins and ticarcillin, showed marked decrease in activity against gentamicin-resistant strains.
Streptococcus pneumoniae is an important cause of community acquired infections, particularly pneumonia, acute otitis media, sinusitis and exacerbations of chronic bronchitis. Together with Haemophilus influenzae, it is an important cause of childhood meningitis. It is also a major cause of bacterial meningitis among adults. The emergence of Streptococcus pneumoniae resistant to penicillin and other antibiotics in recent years has complicated the management of pneumococcal infections world-wide'. In some areas, penicillin resistant strains have become the predominant pneumococcal isolates2. Multiply resistant strains and those resistant to second and third generation cephalosporins are also increasingly reported'. Treatment of meningitis and acute otitis media caused by such strains is particularly problematic. (Copied from article).
Introduction and Objective: Pneumococcal disease is a leading cause of morbidity and mortality worldwide. There were limited publications on invasive pneumococcal infection (IPD) in Malaysia. The aim of this study is to describe restrospectively cases of IPD in hospitalised children of less than 12 years old and highlighting the unusual cases.
Methodology: A retrospective review of children with IPD from March 2002 to November 2005 at a tertiary paediatric hospital. IPD cases were defined as isolates of Streptococcus pneumoniae from a normally sterile body fluid site.
Results: Twenty-four patients were identified with a male preponderance. Two-thirds of patients were below 1-year-old; with three cases presenting in the premature newborn. Thirty-seven percent of cases had underlying conditions. Sepsis and pneumonia were the commonest manifestation, followed by meningitis. The unusual manifestations were in a form of postinfectious glomerulonephritis and overwhelming purpura fulminans. There were two mortalities; both infants had meningitis. Antibiotic susceptibility pattern showed that more than half of the isolates were sensitive towards penicillin and erythromycin. Penicillin resistance was found in 6 (25%) isolates. Conclusion: IPD results in significant morbidity and mortality, especially in young children below 2 years of age and justifies further evaluation of preventive strategies including the implementation of pneumococcal vaccine in the national immunisation programme.
Plesiomonas shigelloides was isolated from 5 (2.1%) of the 234 children with diarrhoea and none of the 230 controls. In one child, the organism was found in association with Salmonella. Two strains had Shigella sonnei phase I antigen. All the strains were susceptible to the aminoglycosides, cephalosporins, nalidixic acid, nitrofurantoin, chloramphenicol and cotrimoxazole; but resistant to the penicillins. Alkaline peptone water enrichment subcultured to desoxycholale citrate agar proved to be a useful method for isolating this organism from faeces. As the roie of P. shigelloides in causing gastrointestinal disease remains controversial, further studies are necessary to determine its enteropathogenicily.
Methicillin resistant Siaphylococcus aureus Is a common isolate from clinical specimens obtained from babies at the special care nursery of the Kuala Lumpur Maternity Hospital. Major Infections due to this organism were, however uncommon and the organism had in the majority of cases been present as a coloniser or as a cause of superficial infection. Netilmicin is a valuable antibiotic in the treatment of the severe infections.
Staphylococcal infection is common in Malaysian hospitals. A recent survey of 22 Malaysian hospitals revealed that staphylococci were isolated from almost 40% of positive blood cultures. A more detailed analysis of such cases in our own hospital showed that almost 70% of Staphylococcus aureus and about 16% of coagulase-negative staphylococcal isolates were associated with clinically-significant disease. Staphylococcal bacteraemia was seen mainly in neonatal sepsis, skin and soft tissue infections, pneumonia, arthritis, osteomyelitis, endocarditis and postoperative sepsis. Multiply-resistant S. aureus were encountered in all the hospitals surveyed. Resistance rates to penicillin ranged from 40% to almost 100% while methicillin resistance rates of up to 25% were reported from several hospitals.
We have previously reported the phenotypic characterization of methicillin-resistant Staphylococcus aureus (MRSA) clinical strains isolated in Malaya University Hospital in the period 1987 to 1989 using antibiogram, coagulase typing, plasmid profiles, and phage typing. Here, we report the analysis of the same strains with three genotyping methods; ribotyping, pulsed-field gel electrophoresis (PFGE) typing, and IS431 typing (a restriction enzyme fragment length polymorphism analysis using an IS431 probe). Ribotyping could discriminate 46 clinical MRSA strains into 5 ribotypes, PFGE typing into 22 types, and IS431 typing into 15 types. Since the differences of the three genotyping patterns from strain to strain were quite independent from one another, the combined use of the three genotyping methods could discriminate 46 strains into 39 genotypes. Thus, the powerful discriminatory ability of the combination was demonstrated.