Drug Resistance Characteristics and Macrolide-Resistant Mechanisms of Streptococcus pneumoniae in Wenzhou City, China

Recent development and fighting strategies for lincosamide antibiotic resistance

SUMMARYLincosamides constitute an important class of antibiotics used against a wide range of pathogens, including methicillin-resistant Staphylococcus aureus. However, due to the misuse of lincosamide and co-selection pressure, the resistance to lincosamide has become a serious concern. It is urgently needed to carefully understand the phenomenon and mechanism of lincosamide resistance to effectively prevent and control lincosamide resistance. To date, six mobile lincosamide resistance classes, including lnu, cfr, erm, vga, lsa, and sal, have been identified. These lincosamide resistance genes are frequently found on mobile genetic elements (MGEs), such as plasmids, transposons, integrative and conjugative elements, genomic islands, and prophages. Additionally, MGEs harbor the genes that confer resistance not only to antimicrobial agents of other classes but also to metals and biocides. The ultimate purpose of discovering and summarizing bacterial resistance is to prevent, control, and combat resistance effectively. This review highlights four promising strategies, including chemical modification of antibiotics, the development of antimicrobial peptides, the initiation of bacterial self-destruct program, and antimicrobial stewardship, to fight against resistance and safeguard global health.

Antimicrobial resistance in beta-haemolytic streptococci in India: A four-year study

Background & objectives:

The incidence and severity of invasive and non-invasive infections demonstrate variability over time. The emerging resistance of Group A streptococci (GAS) to commonly used antibiotics is of grave concern. This study was conducted to assess the antimicrobial resistance of beta-haemolytic streptococci (βHS) in India and to ascertain the molecular mechanisms of resistance.

Methods:

All isolates of βHS from the Trauma Centre of All India Institute of Medical Sciences (AIIMS) (north India), and heavily populated area of old Delhi from 2010 to 2014 and Yashoda Hospital, Secunderabad (in south India, 2010-2012) and preserved isolates of βHS at AIIMS (2005-2009) were included. Phenotypic confirmation was done using conventional methods and the Vitek 2. Antibiotic sensitivity testing was done by disc diffusion and E-test. Detection of resistance genes, erm(A), erm(B), mef(A), tet(M) and tet(O), was done by polymerase chain reaction (PCR).

Results:

A total of 296 isolates of βHS (240 from north and 21 from south India) were included in the study. Of the 296 βHS, 220 (74%) were GAS, 52 (17.5%) were Group G streptococci and 11 (3.7%), 10 (3.3%) and three (1%) were Group B streptococci, Group C streptococci and Group F streptococci, respectively. A total of 102 (46%) and 174 (79%) isolates were resistant to tetracycline and erythromycin, respectively; a lower resistance to ciprofloxacin (21, 9.5%) was observed. A total of 42 (14%) and 30 (10%) isolates, respectively, were positive for tet(M) and erm(B) genes. Only 13 (5%) isolates were positive for mef(A). None of the isolates were positive for erm(A) and tet(O). There was discordance between the results of E-test and PCR for erythromycin and tetracycline.

Interpretation & conclusions:

A high level of resistance to erythromycin and tetracycline was seen in βHS in India. Discordance between genotypic and phenotypic results was reported. Absence of erm(A) and tet(O) with high prevalence of tet(M) and erm(B) was observed.