Macrolides inhibit the growth of bacterial cells by preventing the elongation of polypeptides during protein biosynthesis and includes natural, synthetic, and semisynthetic products. This occurs by blocking the passage of the polypeptide chain as macrolides bind at the nascent peptide exit tunnel. Recent data of ribosome profiling via ribo-seq further proves that other than blocking the polypeptide chain, macrolides are also able to affect the synthesis of individual proteins. Thus, this shows that the mode of action of macrolides is more complex than we initially thought. Since the discovery of macrolides in the 1950s, they have been widely used in veterinary, agriculture, and medicine. Due to misuse and overuse of antibiotics; bacteria have acquired resistance against them. Hence, it is of utmost importance for us to fully understand the mode of action of macrolides as well as the mechanism of resistance against macrolides to mitigate the antibiotic resistance issues. With a better understanding on the mode of actions of macrolides, chemical modifications can be performed to improve its potency. Furthermore, the complete detailed understanding of the mode of action of macrolides remained vague as new findings challenged the theory that was already in existence - due to this obscurity, research into macrolides' mode of action continues up to this day. In this review, we present an overview of macrolide antibiotics with the emphasis on the latest knowledge regarding the mode of action of macrolides and mechanism of resistance employed in bacteria against macrolides.

Invasive Salmonella infections result in significant morbidity and mortality in developing countries. In Asia, typhoid and paratyphoid fever are reported to be the major invasive Salmonella infections, while invasive non-typhoidal Salmonella (iNTS) infections are believed to be uncommon. Data from Sarawak, in Malaysian Borneo, are limited. A retrospective study identifying all children aged < 15 years with invasive Salmonella infections from 2011 to 2016 was conducted in Bintulu Hospital in Sarawak. Population incidences, clinical and bacterial characteristics were examined. Forty-four patients were identified during the 6-year study period: 43 had iNTS infection and 1 had typhoid fever. The average annual iNTS incidence was 32.4 per 100,000 children aged < 5 years. None of the children had malaria or HIV infection, and only 7% were severely malnourished. Salmonella Enteritidis and Salmonella Java were the commonest NTS serovars identified. Pneumonia was the most common manifestation of iNTS disease, present in 20 (47%) children. Other manifestations included gastroenteritis, fever without a source, septic arthritis and meningitis. Salmonella Enteritidis was identified in 76% of those with pneumonia, significantly more frequently than in children with other manifestations. Over 25% of children with iNTS developed severe disease and nearly 10% suffered long term morbidity or mortality. While 78% of Salmonella Java isolates were multi-drug resistant, nearly all other isolates were susceptible to most antimicrobials, including ampicillin. Bintulu Division in Sarawak observed a very high incidence of childhood iNTS infections. Enteric fever was uncommon. The epidemiology of invasive Salmonella infections in Malaysian Borneo differs considerably from that of neighbouring countries in Asia.

Background. The spread of carbapenem-resistantA. baumannii(CrAb) is gaining worldwide attention. The spread of this pathogen is largely due to its ability to acquire various resistance genes of intrinsic and extrinsic origins that confer unpredictable susceptibility toβ-lactams. The aim of this study was to analyzeβ-lactamase genetic compositions of CrAb in Malaysia.Methods. Whole-genome sequencing (WGS) was carried out on 13 CrAb isolates from clinical samples in Malaysia from 2011 to 2016.Results. Endotracheal aspirate was the dominant clinical sample source (n = 6), and only one isolate was obtained from wound swab. A total of 6 sequence types (STs) of the Oxford scheme were identified, including 4 reported STs and 2 novel STs. Eleven isolates were classified into clonal complex 92 (CC92/ICII), among which ST195 and ST208 were the most prevalent STs. All 13 CrAb isolates harbored multipleβ-lactamase genes.bla_OXA-23(n = 13) andbla_OXA-66(n = 11) were the dominant carbapenemase gene families found in these isolates. All isolates harborbla_ADC,bla_OXA-51-like, andbla_OXA-23-likegenes.bla_TEM(n = 7),bla_NDM-1(n = 3),bla_CARB-8(n = 1), andbla_PER-3(n = 1) are amongst otherβ-lactamase genes found in this study. ISAba1was found upstream tobla_OXA-23(n = 13),bla_OXA-66(n = 1), andbla_ADC(n = 11). Allbla_NDM-1isolates had ISAba125(mobile genetic element) upstream to the genes. All isolates were positive for Tn2006/2008and Tn2009but were negative for Tn2007.Conclusion. Most of the isolates were grouped under the CC92 clonal complex which belongs to international clonal lineage 2. These findings predict that carriage of carbapenem-resistant genes possibly constitutes the underlying basis of high level of international clone II prevalence. Therefore, molecular surveillance and antimicrobial stewardship are essential in implementing policies to prevent and control the spread of CrAb in hospital settings.

Brucellosis is a world-wide zoonotic disease with a major impact on the public health. Due to the high risk of laboratory acquired infection, limited laboratory investigations were performed on this organism, including detailed identification and susceptibility study.Brucella melitensisis the commonest aetiological agent for human brucellosis in this region. The in vitro susceptibility pattern against selected antimicrobial agents was assessed usingE-test. All isolates were noted to be sensitive to all the antimicrobial agents tested except for rifampicin where elevated MIC > 1 μg/mL was noted in 30 out of 41 isolates tested.

Brucellosis is one of the most common zoonotic diseases worldwide. It can cause acute febrile illness in human and is a major health problem. Studies in human brucellosis in Malaysia is limited and so far no genotyping studies has been done on Brucella isolates. The aim of the study was to determine the genetic diversity among Brucella species isolated from human brucellosis, obtained over a 6-year period (2009–2014). In this study, the genotypic characteristics of 43 human Brucella melitensis isolates were analysed using multiple-locus variable-number tandem-repeat analysis (MLVA) which consisted of eight minisatellite loci (panel 1) and eight microsatellite loci; panels 2A (3 microsatellite loci) and panel 2B (5 microsatellite loci). Two human Brucella suis isolates were also investigated using the MLVA assay. Using panel 1 (MLVA8), two genotypes namely genotype 43 and 44 were obtained from the 43 B. melitensis isolates. Using the combination of panels 1 and 2A loci (MLVA11), two genotypes were obtained while using the complete panels 1, 2A and 2B, nine genotypes were obtained. The polymorphisms in using the complete panels (MLVA16) were observed in three loci from panel 2B, which showed a diversity index higher than 0.17. All B. melitensis isolates were closely related to the East Mediterranean group. For B. suis isolates, only genotype 6 and genotype 33 were obtained using panel 1 and MLVA11 respectively. In conclusion, the results of the present study showed a low genetic diversity among B. melitensis and B. suis isolates from human patients. Based on the MLVA16 assay, B. melitensis belonging to the East Mediterranean group is responsible for the vast majority of Brucella infections in our Malaysian patients. To our knowledge, this is the first genotyping study of human Brucella isolates in Malaysia.

The number of new fungal pathogens is increasing due to growing population of immunocompromised patients and advanced identification techniques. Fereydounia khargensis is a yeast and was first described in 2014 from environmental samples. As far as we know, this is the first report of human infections associated with F. khargensis. The yeasts were isolated from blood of a HIV-positive patient and pleural fluid of chronic renal failure patient. Amplification and sequencing of the internal transcribed spacer and the large subunit regions confirmed the identity of the isolates. Both isolates showed multi-drug resistance to antifungal agents tested.