Molecular epidemiology of piliated pneumococcal isolates at a major tertiary hospital in the Klang Valley, Malaysia

Objective: To characterise a collection of pili-carrying and none pili-carrying pneumococcal isolates of clinical origin for serotypes, antibiotic resistance and genotype. Methods: In total, 42 clinical isolates were collected between October 2017 and December 2019. Those isolates were analysed for antimicrobial susceptibility, serotype distribution, detection of pneumococcal virulence and pilus genes. Multilocus sequence typing was performed only for piliated isolates, followed by phylogenetic analysis. Results: The common isolation sites among the pneumococcal isolates were tracheal aspirate (28.6%), blood (26.2%), and sputum (23.8%). Fifty percent isolates were resistant to erythromycin, tetracycline (50.0%) and trimethoprim-sulfamethoxazole (43.0%). The most frequent were serotypes 19F (28.6%), 6A/B (23.8%) and 19A (14.3%). Piliated isolates were detected in a small proportion (33.3%); 64.3% were multidrug-resistant. ST320 was the prevalent sequence type among the piliated isolates and genetically related to the Pneumococcal Molecular Epidemiology Network clones Taiwan 19F -14 (CC271). In the phylogenetic analysis, some piliated isolates showed a close association having similar ST320, carrying serotype 19A and both pilus genes indicating their clonal spread. Conclusions: Pneumococcal lineages of piliated isolates have been globally disseminated and pili could have played a role in the spread of antibiotic resistant clones.

Detection of Pathogenic Leptospira in Rats and Phylogenetic Analysis Using Outer Membrane Lipoprotein Lipl32 Gene at Two Major Public Markets

@#Introduction: Limited studies have been documented on the presence of pathogenic Leptospira in public markets serving the community in sub-districts of Selangor. The aim of this study was to detect the presence of pathogenic Leptospira in rats using a gene encoding an outer membrane lipoprotein LipL32. Methods: Polymerase chain reaction (PCR) was performed using LipL32 primers on sixty kidney samples of rats trapped at two locations of study; Pasar Borong Selangor in Seri Kembangan and Pasar Basah Bandar Baru Bangi in Bangi. Results: Out of 60 samples analysed, 36.7% were positive for the presence of LipL32. All positive samples highly matched (>94%) nucleotide sequence for LipL32 of pathogenic Leptospira and related to the pathogens through phylogenetic analysis. Conclusion: The detection of LipL32 indicates the potential presence of pathogenic Leptospira species at public markets. Although only 60 rats were successfully trapped, the rats are mobile and might further transmit the pathogenic organisms to other areas.

Assessment of Pathogenicity of Community-Acquired MRSA Isolates in Mice-Induced Peritonitis

@#Introduction: Methicillin-Resistance Staphylococcus aureus (MRSA) is known as a major nosocomial pathogen in healthcare. However, it has now spread in the community known as community-acquired MRSA (CA-MRSA). Thus, the survival and pathogenicity of CA-MRSA isolates were assessed using in vivo peritonitis model with comparison to ATCC-MRSA. Two CA-MRSA isolates; CA-MRSA1 and CA-MRSA2 that were isolated from healthy population, were studied and compared. Methods: Mice were assigned into 4 groups and injected intraperitoneally with ATCC-MRSA, CA-MRSA1 or CA-MRSA2, respectively. Sterile Dulbecco’s Phosphate-Buffered Saline (DPBS) represents negative control. Mice were observed twice daily, 0-72 hours of post-infection. Any signs of distress were recorded for severity score and survival analyses. Mice were euthanised at 72 hours post-inoculation or by referring to the Peritonitis Severity Scoring (PSS) system. Organs of interest, peritoneal lavage and abscess were processed for bacterial counts. Tissue samples were analysed for histopathological scores. Results: All mice inoculated with MRSA showed clear signs of illness with peritonitis symptoms of p<0.001 and comparable PSS scores were recorded in all infected mice groups. Intraperitoneal injection of lethal dose of MRSA resulted in significant death of ATCC-MRSA (p<0.05) and CA-MRSA-infected mice (p<0.01), compared to the un-infected. Bacterial burden was significantly high in all samples harvested from mice challenged with CA-MRSA2 compared to ATCC-MRSA except in abscess and lung. Significant liver necrosis and spleen inflammation were observed in CA-MRSA1, and lung inflammation in ATCC-MRSA-infected mice. Conclusion: Nasal carriage CA-MRSA isolates from a healthy population has the potential to cause peritonitis with comparable severity as ATCC-MRSA.

Distribution of virulence genes and the molecular epidemiology of Streptococcus pyogenes clinical isolates by emm and multilocus sequence typing methods

@#Background: Streptococcus pyogenes has a variety of virulence factors and the predominant invasive strains differ according to specific emm types and geographical orientation. Although emm typing is commonly used as the gold standard method for the molecular characterisation, multilocus sequence typing (MLST) has become an important tool for comparing the genetic profiles globally. This study aimed to screen selected virulence genes from invasive and non-invasive clinical samples and to characterise the molecular epidemiology by emm typing and MLST methods. Materials and Methods: A total of 42 S. pyogenes isolates from invasive and non-invasive samples collected from two different tertiary hospitals were investigated for the distribution of virulence factors and their molecular epidemiology by emm and multilocus sequence typing methods. Detection of five virulence genes (speA, speB, speJ, ssa and sdaB) was performed using multiplex polymerase chain reaction (PCR) using the standard primers and established protocol. Phylogenetic tree branches were constructed from sequence analysis utilised by neighbour joining method generated from seven housekeeping genes using MEGA X software. Results: Multiplex PCR analysis revealed that sdaB/speF (78.6%) and speB (61.9%) were the predominant virulence genes. Regardless of the type of invasiveness, diverse distribution of emm types/subtypes was noted which comprised of 27 different emm types/subtypes. The predominant emm types/subtypes were emm63 and emm18 with each gene accounted for 11.8% whereas 12% for each gene was noted for emm28, emm97.4 and emm91. The MLST revealed that the main sequence type (ST) in invasive samples was ST402 (17.7%) while ST473 and ST318 (12% for each ST) were the major types in non-invasive samples. Out of 18 virulotypes, Virulotype A (five genes, 55.6%) and Virulotype B (two genes, 27.8%) were the major virulotypes found in this study. Phylogenetic analysis indicated the presence of seven different clusters of S. pyogenes. Interestingly, Cluster VI showed that selected emm/ST types such as emm71/ST318 (n=2), emm70.1/ST318 (n=1), emm44/ST31 (n=1) and emm18/ST442 (n=1) have clustered within a common group (Virulotype A) for both hospitals studied. Conclusion: The present study showed that group A streptococcci (GAS) are genetically diverse and possess virulence genes regardless of their invasiveness. Majority of the GAS exhibited no restricted pattern of virulotypes except for a few distinct clusters. Therefore, it can be concluded that virulotyping is partially useful for characterising a heterogeneous population of GAS in hospitals.

Proteomic profiling of Acinetobacter baumannii ATCC 19606 and Malaysian isolated clinical strain AB-13 using 2-dimensional gel electrophoresis

Aims@#Acinetobacter baumannii has been identified as one of the six most pathogenic bacteria that is the cause of most hospital bacterial infections according to Infectious Disease Society of America (IDSA). These nosocomial pathogens are notorious worldwide due to its ability in causing lethal infections among immunocompromised patients and its resistance to many strong antibiotics. This study aims to compare the expressed proteins of two A. baumannii strain, ATCC 19606 and a pathogenic clinically isolated strain known as AB-13. @*Methodology and results@#AB-13 clinically strain was isolated from the lower respiratory tract of a patient with pneumonia. In this study, the proteomic profile of both ATCC 19606 and AB-13 are produced using 2-dimensional gel electrophoresis. The total protein contents were extracted, quantified and separated using 2-DE with a pH range of 4-7 to acquire the proteomic profile for comparison. The final analytical gel was analysed using Delta2D software and among the 324 protein spots successfully resolved, 10 spots exhibited signs of differential expression with 7 spots found to be downregulated and 3 spots upregulated (p< 0.01). These differences could signify the evolution AB-13 has undergone as it acquires traits ultimately aiding in its survivability, antimicrobial resistance and pathogenicity within varied environments especially during infections.@*Conclusion, significance and impact of study@#These findings support the presence of variation in AB-13 from a proteomic perspective, highlighting the pathogen’s evolution improving survivability and pathogenicity, warranting in-depth exploration towards understanding A. baumannii virulence and pathogenicity.

Multilocus Sequence Typing Analysis of Invasive and Non-Invasive Group B Streptococcus of Hospital Origin in Malaysia

@#The aim of this study was to study the genotype of a hospital collection of Group B Streptococcus (GBS) from invasive and non-invasive sites. Fifty-one pre-characterised human of GBS were re-identified and further analysed by multilocus sequence typing (MLST) in relation to previously published serotypes. Fifteen sequence types (ST) were found with ST1 being the most predominant. ST1 was also associated with majority of the invasive isolates. The genotypic distribution patterns of GBS in this study were largely in agreement with previous reports from other countries indicating the tendency of certain genotypes to prevail in human infection settings.

The Effectiveness of Non-dominant Hand in Performing Oral Hygiene Care

@#Introduction: This study aimed to assess the effectiveness of dental plaque removal and to determine factors that could influence its efficacy when using the non-dominant hand. Methods: A quasi-experimental study was performed on a group of dental students. Dominant hands were determined using Edinburg Handedness Inventory questionnaire, and the dental plaque scores were examined using Quigley-Hein (Turesky) index. All of the participants were examined twice for dental plaque index scores. Data obtained was analyzed using a paired t-test and an independent t-test. Factors which influenced the dental plaque removal were listed and categorized accordingly. Results: A total of 62 dental undergraduates participated in the study. A high percentage of them, (71%, n = 44) were found to be right-handed. There was a significant increase in the dental plaque score for the left-handed participants, from baseline (use of the dominant hand) to follow-up appointment (after brushing their teeth with non-dominant hands) (p< 0.01). A significant change was found between the right- and left-handed participants in the first quadrant of the buccal side (p<0.05). Factors identified to be beneficial in dental plaque control were; using a mirror while brushing, extending brushing time, increasing brushing frequency, using additional tooth aids and powered toothbrushes. Conclusions: This study revealed that left-handed participants have less ability to remove dental plaque with their non-dominant hands. The right-handed participants, showed better controls in plaque removal with their non-dominant hands, compared to their left-handed peers on the buccal side of the first quadrant.

Presence of methicillin resistance and heteroresistance among Coagulase Negative Staphylococci (CoNS) isolates obtained from Health Sciences students at a Public University

This study was carried out to investigate the Coagulase Negative Staphylococci (CoNS) nasal carriage and the presence of methicillin resistant Coagulase Negative Staphylococci (MR-CoNS) among health sciences students at Faculty of Medicine and Health Sciences, Universiti Putra Malaysia. A total of 120 isolates of CoNS (62.5%) was isolated from 192 student volunteers. The mecA gene was detected in 15 isolates of CoNS (12.5%). Eight out of the 15 isolates of mecA positive CoNS were resistant to cefoxitin in disc diffusion test whereas the remaining seven isolates of mecA positive CoNS were susceptible to cefoxitin. Analysis of questionnaires showed no significant association between CoNS nasal carriage and the socio-demographic and risk factors except for the genders and history of cold (P < 0.050). Generally, this finding showed a relatively low level of methicillin resistance among CoNS nasal carriage from student volunteers.

Genotypic and phenotypic characterization of methicillin resistance determinants and β-lactamase in Staphylococcus species

Aims: To characterize the genotypic distribution of mec complex, bla complex, methicillin-resistance level (cefoxitinMIC) and β-lactamase activity in carriage methicillin-resistant Staphylococcus species for a potential correlation. Methodology and results: Biochemical test, 30 µg cefoxitin diffusion disc test, cefoxitin E-test, mec and bla complexes distributions, Pbp2a and β-lactamase assays were conducted to characterize phenotypic and genotypic of MRSA and MRCoNS in our collection. Phylogenetic tree was constructed using MEGA6 software to trace the diversity of blaZ gene of MRSA and MRCoNS. Sixteen MRSA and nineteen MRCoNS were identified by biochemical tests followed by 30 µg cefoxitin antibiotic disc susceptibility test and mecA gene screening. Twenty nine isolates carry complete mecA genes (2.1 kb), incomplete mec regulator (negative or truncated) and positive Pbp2a assay for both MRSA and MRCoNS. Only MRCoNS SC177 isolate with cefoxitin MIC of 32 µg/mL carries complete mec complex. Thirty-one of thirty-five isolates carry complete bla complex (blaZ, blaRI, blaI) with 10 MRSA produce strong β-lactamase and cefoxitin MIC of ≥12 µg/mL. Only 4 MRCoNS with cefoxitin MIC of ≤8 µg/mL produce strong β-lactamase. The diversity of blaZ gene was demonstrated by phylogenetic analysis and unusual amino acid mutation at position 145 for MRSA SA60 isolate may compromise its β-lactamase activity with low cefoxitin MIC level (2 µg/mL). Conclusions, significance and impact of the study: Isolates that carry complete complete mecA gene were largely consistent with the expression of Pbp2a. Nevertheless, there is no clear correlation of mec regulator genes in relation to cefoxitin-MIC in both methicillin resistant (MR) Isolates that carry Staphylococcus species. On the other hand, various expression level of β-lactamase may correlate with cefoxitin-MIC level in MRSA as compared to MRCoNS.

The emergence of Acinetobacter baumannii ST-6 multidrug resistant: A resilient biofilm producer, Malaysia

Aims: The aim of this research is to explore the presence of multidrug-resistance (MDR) Acinetobacter baumannii strains isolated from hospitalized patients in a tertiary-care center, Subang Jaya, Selangor, Malaysia and to compare their genotypic and phenotypic characteristics. Methodology and results: Clonal relationships were determined by multilocus sequence typing (MLST) and biofilm forming ability was evaluated by using 2, 3 - bis (2 - methoxy - 4 - nitro - 5-sulfophenyl) - 5 - [(phenylamino) carbonyl] - 2H-tetrazolium hydroxide (XTT) reduction assay in microplates and Congo red agar method (CRA). Four virulence genes coding for A. baumannii pilus usher-chaperone assembly protein, csuE gene; outer membrane protein, ompA gene; biofilm poly-β-1, 6-Nacetylglucosamine (PNAG) synthesis protein, pgaA gene; and acinetobactin-mediated iron acquisition protein, bauA gene were searched for in a collection of strains. Antimicrobial resistance against 11 antibiotics were studied by broth microdilution method. Seventeen A. baumannii clinical strains were isolated and MLST showed that the strains belonged to 5 distinct sequence types (STs), namely, ST-6, ST-265, ST-324, ST-325 and ST-432. Fiftythree percent of the strains were resistant to 4 or more antibiotics. Twelve strains produced biofilm and out of them, 4 were strong biofilm producer, besides, these strong biofilm producers were MDR strains and belongs to ST-6. In addition, all strains were ompA positive, biofilm producing strains were csuE and pgaA positive and only strong biofilm producing strains were bauA positive. Conclusion, significance and impact study: Our study demonstrates that the ST-6 strains in Malaysia could represent MDR, capable of forming strong biofilm and possess csuE, ompA, pgaA and bauA genes, virulence characteristics that probably help the bacteria to persist and cause infection.

Prevalence of Escherichia Coli O157:H7 and Enterobacteriaceae on Hands of Workers in Halal Cattle Abattoirs in Peninsular Malaysia

Background: Several occupational diseases of multiple origins are encountered among abattoir workers. Presence of indicator microorganisms (coliforms) on hands of workers can be used a gauge for hygienic practices. Methods: A cross-sectional study was performed to assess the prevalence of E.coli and enterobacteriaceae among Halal abattoir workers in some government halal abattoirs of Malaysia. A total of one hundred and sixty-five hand swab samples were collected from workers of Halal abattoirs in Malaysia. The samples were subjected to microbiological analysis for characterisation and serotyping. Results: The results have shown that no Escherichia coli O157:H7 was isolated on the hands of abattoir workers before and after work. However, a total prevalence of 9.7% was recorded for all samples during work. For non-O157:H7, total prevalence of 33.3% during work and 13% after work were obtained. High prevalence was recorded in sample taken during work from Tampin, Jasin and Kemaman (100% each) while low prevalence where observed in Shah Alam, Banting and Ipoh (20% each). Conclusions: Based on the findings the hygienic practices of hand washing among the workers in few locations was found to be low especially after work.

A rare cause of acute abdomen – Spontaneous rectus sheath hematoma

Spontaneous rectus sheath hematoma (SRSH) is a rare entity that mimics acute abdomen. Rectus sheath hematoma is the accumulation of blood in rectus sheath due to muscle or epigastric vessel injury. However, SRSH without a trauma or anticoagulation is rare. It frequently mimics acute abdomen and it may lead to misdiagnosis and unnecessary laparotomy. In this article, we described two cases of SRSH with their diagnostic and therapeutic strategy. Both of our patients in report were neither consumed antiplatelet nor coagulopathy. They both had abdominal muscle straining before their symptoms presentation. We hypothesized that the SRSH may be induced by rectus muscle injury secondary to inappropriate straining or posture. To diagnose SRSH, clinical findings are important but radiologic imaging such as computed tomography, can be diagnostic. In expanding SRSH, percutaneous arterial embolization of epigastric artery is useful to secure the bleeding. If embolization is not feasible, surgical exploration hemostasis is curative. In non-expanding SRSH, it can be managed nonoperatively. SRSH is an important initial differential for acute abdomen. Radiologic imaging helps in diagnosis. Stable SRSH can be managed conservatively with good outcome.

Effect of aqueous extract of Dicranopteris linearis leaves against paracetamol and carbon tetrachloride-induced liver toxicity in rats

The present study aimed to determine the hepatoprotective activity of Dicranopteris linearis L. [family Gleicheniaceae] leaf aqueous extract [DLAE] using two models of liver injury in rats. Rats were divided into ten groups [n=6] and received dH2O [negative control], 200 mg/kg silymarin [positive control] or DLAE [50, 250 and 500 mg/kg] orally once daily for 7 consecutive days and on the 8th day subjected to the hepatotoxic induction either using carbon tetrachloride [CCl[4]] or paracetamol [PCM]. The bloods and livers were collected and subjected to biochemical and microscopical analysis. From the data obtained, only the highest dose of DLAE significantly [p<0.05] reduced the ALP, ALT and AST levels in CCl[4]-and PCM-induced hepatotoxic rats while the other doses caused significant [p<0.05] reduction only in the levels of ALT and AST. The histological results obtained were in line with the biochemical analysis wherein reduction in the CCl[4]- and PCM-induced tissue formation of necrosis, steatosis and inflammation occurred in a dose-dependent manner. In conclusion, the DLAE possesses hepatoprotective activity, which could be attributed to its free radicals scavenging and antioxidant activities, and high flavonoids content. Thus, in-depth studies regarding the hepatoprotective activity of DLAE are warranted

Prevalence of macrolide resistance and in vitro activities of six antimicrobial agents against clinical isolates of Streptococcus pneumoniae from a multi-center surveillance in Malaysia

The in vitro activities of 6 antimicrobial agents against clinical isolates of Streptococcus pneumoniae (pneumococci) were investigated and the erythromycin minimum inhibitory concentrations (MICs) were correlated with the two major macrolide resistance determinants, mef(A) and erm(B). MICs of commonly used antibiotics as well as the presence of macrolide resistance determinant genes in all isolates were tested. Seventy one pneumococcal isolates collected at Institute for Medical Research (IMR) were included in this study. Phenotypic characterization, MIC determination using E-test strips and polymerase chain reactions for antibiotic resistance determination were included. Among the isolates, 25 (35.2%) isolates were erythromycin susceptible, 3 (4.2%) were intermediate and 42 (60.6%) were resistant. Fifty three isolates (74.7%) were found with mef(A) alone, 15 (21.1%) isolates with erm(B) + mef(A) combination and 3 (4.2%) isolates with none of the two genes. The in vitro activity of penicillin, amoxicillin clavulanic acid, ceftriaxone and cefotaxime is superior to trimethoprim-sulfamethoxazole and erythromycin. In conclusion, pneumococcal isolates in this study were highly susceptible to penicillin with very low MICs. However, a very high prevalence rate of erythromycin resistance was observed. Erythromycin resistant S.pneumoniae isolates with both mef(A) and erm(B) showed very high MICs ≥256 μg/mL.

Staphylococcus aureus Nasal Carriers Among Medical Students in A Medical School

Staphylococcus aureus is usually considered a colonizer but can result in infections under favourable conditions, especially in the healthcare setting. Healthcare workers can be colonized by S. aureus, and may transmit them to patients under their care. We conducted a cross sectional study to determine the prevalence of S. aureus nasal carriers among medical students in Universiti Putra Malaysia (UPM) (from January to June 2011). Our study involved 209 medical students comprising of 111 and 97 preclinical and clinical students respectively. A selfadministered questionnaire was distributed and nasal swabs were collected. Upon identification, the antibiotic susceptibility of the isolates was examined followed by categorical analysis (Chi-square and Fisher’s exact tests) with factors associated with S. aureus nasal carriage. Twenty one (10%) S. aureus strains were isolated from 209 nasal swab samples. 14 isolates were from pre-clinical students while the remaining seven were from clinical students. There was no significant association between gender, ethnicity, health status, skin infection and students’ exposure to hospital environment with S. aureus nasal carriage (p>0.05). Nineteen (90.5%) isolates were resistant to penicillin and there was also no significant association between penicillin resistant and the students’ groups. One (5.3%) isolate was resistant to erythromycin. There was no methicillin-resistant S. aureus isolated in this study.

Characterization and antimicrobial activities of two Streptomyces isolates from soil in the periphery of Universiti Putra Malaysia

This study was to assess the identification and antimicrobial activities of two actinomycete isolates. The two isolates designated as B8 and C2, were isolated from a patch of soil in the peripheral area of Universiti Putra Malaysia by streaking on starch casein agar after standard serial dilution procedures. Their antimicrobial activities were first evaluated against eight clinical laboratory strains namely Bacillus sp., Enterococcus sp., Escherichia coli, Klebsiella sp., Pseudomonas sp., Salmonella sp., Staphylococcus aureus, and Staphylococcus epidermidis by perpendicular streak method on Mueller Hinton and Tryptic Soy agar. In both media, a broad-spectrum antibacterial activity was observed for both isolates, with B8 against all the test bacteria and C2 against five of them (Bacillus sp., E. coli, Pseudomonas sp., S. aureus and S. epidermidis). Re-assessment against E. coli ATCC 25922 and S. aureus ATCC 25923 strains by similar method showed antibacterial activities by isolate B8 against both ATTC strains while C2 only against S. aureus ATCC 25923. Streptomyces griseus ATCC 10137 was included in the later experiment and showed antibacterial activity against both ATCC strains. Subsequently, the two isolates were identified by PCR/sequencing techniques and phylogenetic analysis to be Streptomyces species (>93% homology based on 16S rRNA and rpoB genes). Characterization on cultural characteristic and viable count at different temperatures (37ºC and 28ºC), on different microbiological media (AIA, ISP-2, MHA, NA, PDA and TSA), were performed. More morphological features were observed on ISP-2 for both isolates. A higher growth yield was also observed at 28ºC in all media but in comparing that between the two isolates, isolate B8 outnumbered C2 at all experimental conditions. The observed variation in cultural traits and growth yield indicate unique properties between the two antibiotic-producing isolates

Pneumococcal replicative state in relation to its adherence capacity to A549-cell line: A preliminary in vitro analysis

This study was to compare the replication capacity of pneumococcal isolates (serotypes 1, 7F, 19F and 23F) with their adherence pattern to monolayer cells (A549). For standardization purposes, all isolates showed a normal growth curve in both bacteriological (THB + 0.5% yeast extract with and without 2% FBS) and cell culture media (RPMI + 2% FBS). In the former media, a shorter lag phase was observed for isolate serotypes 1 and 7F in presence of serum while in the later; growth yield was lower for all isolates with stationary phase approaching OD600 of 0.01 as compared to 1.0 in bacteriological media. In the replicative analysis at different growth phases of the isolates in cell culture media, growth capacity at 3 h post-incubation was frequently twice as that at 1 h, and that at early-log phase was frequently higher than that at mid-log phase at both post-incubation times. Adherence was frequently the least at early-log phase although the isolates were in the most active state of replication to increase the number of pneumococcal cells to adhere. At mid- and late-log phases, pneumococcal adherence was frequently higher although the replication was reduced. This study marks the potential correlation between pneumococcal growth fitness and adherence capacity whereby the later may not be superior during the early growth phase.

Comparison of susceptibility test methods to detect penicillin susceptibility in Streptococcus pneumoniae isolates

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.