Corynebacterium oculi-related bacterium may act as a pathogen and carrier of antimicrobial resistance genes in dogs: a case report

BACKGROUND

The genus Corynebacterium comprises well-known animal and human pathogens as well as commensals of skin and mucous membranes. Species formerly regarded as contaminants are increasingly being recognized as opportunistic pathogens. Corynebacterium oculi has recently been described as a human ocular pathogen but has so far not been reported in dogs.

CASE PRESENTATION

Here we present two cases of infection with a novel Corynebacterium sp., a corneal ulcer and a case of bacteriuria. The two bacterial isolates could not be identified by MALDI-TOF MS. While 16 S rRNA gene (99.3% similarity) and rpoB (96.6% identity) sequencing led to the preliminary identification of the isolates as Corynebacterium (C.) oculi, whole genome sequencing revealed the strains to be closely related to, but in a separate cluster from C. oculi. Antimicrobial susceptibility testing showed high minimal inhibitory concentrations of lincosamides, macrolides, tetracycline, and fluoroquinolones for one of the isolates, which also contained an erm(X) and tet-carrying plasmid as well as a nonsynonymous mutation leading to an S84I substitution in the quinolone resistance determining region of GyrA.

CONCLUSIONS

While the clinical signs of both dogs were alleviated by antimicrobial treatment, the clinical significance of these isolates remains to be proven. However, considering its close relation with C. oculi, a known pathogen in humans, pathogenic potential of this species is not unlikely. Furthermore, these bacteria may act as reservoir for antimicrobial resistance genes also in a One Health context since one strain carried a multidrug resistance plasmid related to pNG3 of C. diphtheriae.

Design, Synthesis and Biological Evaluation of Conjugates of 3-O-Descladinose-azithromycin and Nucleobases against rRNA A2058G- or A2059G-Mutated Strains

Structurally unrelated antibiotics MLS_B (macrolide-lincosamide-streptogramin B) compromised with clinically resistant pathogens because of the cross-resistance resulting from the structural modification of rRNA A2058. The structure-activity relationships of a novel 3-O-descladinose azithromycin chemotype conjugating with nucleobases were fully explored with the aid of engineered E. coli SQ110DTC and SQ110LPTD. The conjugates of macrolides with nucleobases, especially adenine, displayed antibacterial superiority over telithromycin, azithromycin and clindamycin against rRNA A2058/2059-mutated engineered E. coli strains at the cost of lowering permeability and increasing vulnerability to efflux proteins against clinical isolates.

Inducible Clindamycin Resistance and Biofilm Production among Staphylococci Isolated from Tertiary Care Hospitals in Nepal

Resistance to antibiotics, biofilm formation and the presence of virulence factors play important roles in increased mortality associated with infection by staphylococci. The macrolide lincosamide streptogramin B (MLS_B) family of antibiotics is commonly used to treat infections by methicillin-resistant isolates. Clinical failure of clindamycin therapy has been reported due to multiple mechanisms that confer resistance to MLS_B. This study aims to find the incidence of different phenotypes of MLS_B resistance and biofilm production among staphylococci. A total of 375 staphylococci were isolated from different clinical samples, received from two tertiary care hospitals in Nepal. Methicillin resistance was detected by cefoxitin disc diffusion method and inducible clindamycin resistance by D test, according to CLSI guidelines. Biofilm formation was detected by the tissue culture plate method and PCR was used to detect ica genes. Of the total staphylococci isolates, 161 (42.9%) were Staphylococcus aureus, with 131 (81.4%) methicillin-resistant strains, and 214 (57.1%) isolates were coagulase-negative staphylococci, with 143 (66.8%) methicillin-resistant strains. The overall prevalence of constitutive MLS_B (cMLS_B) and inducible MLS_B (iMLS_B) phenotypes was 77 (20.5%) and 87 (23.2%), respectively. Both iMLS_B and cMLS_B phenotypes predominated in methicillin-resistant isolates. The tissue culture plate method detected biofilm formation in 174 (46.4%) isolates and ica genes in 86 (22.9%) isolates. Among biofilm producing isolates, cMLS_B and iMLS_B phenotypes were 35 (20.1%) and 27 (15.5%), respectively. The cMLS_B and iMLS_B were 11 (12.8%) and 19 (22.1%), respectively, in isolates possessing ica genes. Clindamycin resistance in the form of cMLS_B and iMLS_B, especially among MRSA, emphasizes the need for routine D tests to be performed in the lab.

Vaginal colonization with antimicrobial-resistant bacteria among women in labor in central Uganda: prevalence and associated factors

BACKGROUND

According to WHO ( CISMAC. Centre for Intervention Science in Maternal and Child health), the antimicrobial resistant bacteria considered to be clinically most important for human health and earmarked for surveillance include extended-spectrum beta-lactamase (ESBL)-producing Enterobacteriaceae, carbapenem-resistant bacteria, methicillin-resistant (MRSA) and, macrolide-lincosamide-streptogramin B -resistant vancomycin-resistant (VRSA) Staphylococcus aureus and vancomycin-resistant Enterococcus (VRE). If these bacteria are carried in the female genital tract, they may be transmitted to the neonate causing local or systemic neonatal infections that can be difficult to treat with conventionally available antimicrobials. In order to develop effective treatment strategies, there is need for updated information about the prevalence of colonization with important antimicrobial-resistant pathogens.

OBJECTIVE

We sought to estimate the prevalence of vaginal colonization with potentially pathogenic and clinically important AMR bacteria among women in labour in Uganda and to identify factors associated with colonization.

METHODS

We conducted a cross-sectional study among HIV-1 and HIV-2 negative women in labour at three primary health care facilities in Uganda. Drug susceptibility testing was done using the disk diffusion method on bacterial isolates cultured from vaginal swabs. We calculated the prevalence of colonization with potentially pathogenic and clinically important AMR bacteria, in addition to multidrug-resistant (MDR) bacteria, defined as bacteria resistant to antibiotics from ≥ 3 antibiotic classes.

RESULTS

We found that 57 of the 1472 enrolled women (3.9% prevalence; 95% Confidence interval [CI] 3.0%, 5.1%) were colonized with ESBL-producing Enterobacteriaceace, 27 (1.8%; 95% CI 1.2%, 2.6%) were colonized with carbapenem-resistant Enterobacteriaceae, and 85 (5.8%; 95% CI 4.6%, 7.1%) were colonized with MRSA. The prevalence of colonization with MDR bacteria was high (750/1472; 50.9%; 95% CI 48.4%, 53.5%). Women who were ≥ 30 years of age had higher odds of being colonized with MDR bacteria compared to women aged 20-24 years (OR 1.6; 95% CI 1.1, 2.2).

CONCLUSION

Most of the women included in our study were vaginally colonized with potentially pathogenic MDR and other clinically important AMR bacteria. The high prevalence of colonization with these bacteria is likely to further increase the incidence of difficult-to-treat neonatal sepsis.

Inducible clindamycin resistance in clinical isolates of staphylococcus aureus in Suez Canal University Hospital, Ismailia, Egypt

INTRODUCTION

The increasing incidence of methicillin resistance among Staphylococci has led to renewed interest in the usage of macrolide-lincosamide-streptogramin B (MLSB) antibiotics to treat S. aureus infections, with clindamycin being the preferable agent owing to its excellent pharmacokinetic properties. Inducible clindamycin resistance my lead to therapeutic failure.

AIM

Detection of the prevalence of constitutive and inducible clindamycin resistance in clinical isolates of S. aureus to improve the clinical outcomes in patients.

METHODOLOGY

A total of 176 non-duplicate staphylococcal isolates were isolated from different clinical samples. Methicillin resistance was detected using Cefoxitin disk diffusion (CDD) method. Phenotypic clindamycin resistance was performed for all isolates by D test. Polymerase Chain Reaction (PCR) assay were done for detection of erm resistance genes (ermA, ermB and ermC).

RESULTS

Out of 176 strains of S. aureus, 108 isolates (61.3%) were identified as MRSA. Erythromycin and clindamycin resistance was detected in 96 isolates (54.5%) and 68 isolates (38.6%) respectively. Clindamycin resistance (cMLSB) was significantly higher (p value < 0.001) in MRSA strains (56 isolates) compared to MSSA (12 isolates). Resistant genes were detected in 160 isolates (91%). The ermA gene was detected in 28 isolates (16%), the ermB gene was detected in 80 isolates (45.5%) (p < 0.001).

CONCLUSIONS AND RECOMMENDATIONS

The frequency of constitutive and inducible clindamycin resistance in MRSA isolates emphasizes the need to use D test in routine antimicrobial susceptibility testing to detect the susceptibility to clindamycin as the inducible resistance phenotype can inhibit the action of clindamycin and affect the treatment efficacy.

Genetic Characterization of Methicillin-Resistant Staphylococcus aureus Isolates from Human Bloodstream Infections: Detection of MLSB Resistance

In this study we aimed to characterize antimicrobial resistance in methicillin-resistant Staphylococcus aureus (MRSA) isolated from bloodstream infections as well as the associated genetic lineages of the isolates. Sixteen MRSA isolates were recovered from bacteremia samples from inpatients between 2016 and 2019. The antimicrobial susceptibility of these isolates was tested by the Kirby–Bauer disk diffusion method against 14 antimicrobial agents. To determine the macrolide–lincosamide–streptogramin B (MLS_B) resistance phenotype of the isolates, erythromycin-resistant isolates were assessed by double-disk diffusion (D-test). The resistance and virulence genes were screened by polymerase chain reaction (PCR). All isolates were characterized by multilocus sequence typing (MLST), spa typing, staphylococcal chromosomal cassette mec (SCCmec) typing, and accessory gene regulator (agr) typing. Isolates showed resistance to cefoxitin, penicillin, ciprofloxacin, erythromycin, fusidic acid, clindamycin, and aminoglycosides, confirmed by the presence of the blaZ, ermA, ermC, mphC, msrA/B, aac(6’)-Ie-aph(2’’)-Ia, and ant(4’)-Ia genes. Three isolates were Panton–Valentine-leukocidin-positive. Most strains (n = 12) presented an inducible MLS_B phenotype. The isolates were ascribed to eight spa-types (t747, t002, t020, t1084, t008, t10682, t18526, and t1370) and four MLSTs (ST22, ST5, ST105, and ST8). Overall, most (n = 12) MRSA isolates had a multidrug-resistance profile with inducible MLS_B phenotypes and belonged to epidemic MRSA clones.

New Gene Responsible for Resistance of Clinical Corynebacteria to Macrolide, Lincosamide and Streptogramin B

The subject of the study was phenotypic marking of the antibiotic susceptibility and MLS_B resistance mechanism in Corynebacterium spp. isolated from human skin (18 isolates) and from clinical materials (19 isolates). The strains were tested for the presence of the erm(A), erm(B), erm(C), erm(X), lnu(A), msr(A), msr(B) and mph(C) genes. Clinical isolates showed wide resistance to antibiotics. In 89% clinical isolates and 72% skin microbiota a constitutive type of MLS_B resistance was found. In 12 clinical isolates the erm(C) gene was detected-eight of which had erm(X) as well as erm(C), two harboured erm(X), erm(C) and erm(A) and two demonstrated only erm(C).

Differences in distribution of MLS antibiotics resistance genes in clinical isolates of staphylococci belonging to species: S. epidermidis, S. hominis, S. haemolyticus, S. simulans and S. warneri

Background

Macrolides and lincosamides are two leading types of antibiotics commonly used in therapies. The study examines the differences in resistance to these antibiotics and their molecular bases in S. epidermidis as well as in rarely isolated species of coagulase-negative staphylococci such as S. hominis, S. haemolyticus, S. warneri and S. simulans. The isolates were tested for the presence of the erm(A), erm(B), erm(C), lnu(A), msr(A), msr(B), mph(C), ere(A) and ere(B) genes. Phenotypic resistance to methicillin and mecA presence were also determined.

Results

The MLS_B resistance mechanism was phenotypically found in isolates of species included in the study. The most prevalent MLS_B resistance mechanism was observed in S. hominis, S. haemolyticus and S. epidermidis isolates mainly of the MLS_B resistance constitutive type. Macrolide, lincosamide and streptogramin B resistance genes were rarely detected in isolates individually. The erm(B), ere(A) and ere(B) genes were not found in any of the strains. The erm(A) gene was determined only in four strains of S. epidermidis and S. hominis while lnu(A) was seen in eight strains (mainly in S. hominis). The erm(C) gene was present in most of S. epidermidis strains and predominant in S. hominis and S. simulans isolates. The examined species clearly differed between one another in the repertoire of accumulated genes.

Conclusions

The presence of genes encoding the MLS_B resistance among CoNS strains demonstrates these genes’ widespread prevalence and accumulation in opportunistic pathogens that might become gene reservoir for bacteria with superior pathogenic potential.

Nasal colonisation, antimicrobial susceptibility and genotypic pattern of Staphylococcus aureus among agricultural biotechnology students in Besut, Terengganu, east coast of Malaysia

BACKGROUND

This study aimed to profile the antimicrobial susceptibility and presence of resistance and virulence genes of methicillin-susceptible Staphylococcus aureus (MSSA) and MRSA nasal carriage, by means of genotypic analyses, in students of a tertiary institution in the state of Terengganu, east coast of Malaysia.

METHODS

A total of 370 agricultural biotechnology students from Universiti Sultan Zainal Abidin in Besut, Terengganu, were enrolled in this study. Antimicrobial susceptibility profiles were evaluated by standard methods. PCR detection of resistance and virulence genes was performed on S. aureus that were methicillin-resistant, macrolide-lincosamide-streptogramin B (MLS_B )-positive phenotype and/or positive for the leukocidin (pvl) gene followed by staphylococcal cassette chromosome mec (SCCmec), staphylococcal protein A (spa) and accessory gene regulator (agr) typing.

RESULTS

One hundred and nineteen of 370 students carried S. aureus (32%); 18 of the isolates were MRSA (15%). Erythromycin resistance was detected in 20% (24/119) of which 15% (18/119) were MRSA and 5% (6/119) MSSA. Among the 24 erythromycin-resistant isolates, D-test was positive in 29% (7/24) displaying inducible MLS_B , whereas the remaining 71% (17/24) showed constitutive MLS_B phenotypes. Nine (7.6%) of 119 isolates were pvl positive: 44% MRSA (4/9) and 56% MSSA (5/9). Staphylococcal surface protein sasX gene was present in 92% of MRSA and 8% of MSSA isolates. The majority of MRSA isolates were agr type I (15/18; 83%). Five spa types identified with spa t037 were predominant, followed by spa types (t304 and t8696) as newly reported Malaysian MRSA in a community setting.

CONCLUSION

The presence of MRSA with SCCmec of hospital-associated features and globally recognised spa types in community setting is worrisome. Furthermore, the presence of MLS_B strains among multidrug-resistant (MDR) S. aureus with sasX as well as pvl-positive isolates highlights the potential risk of a community setting in facilitating the dissemination of both virulence and resistance determinants.

Characterization of resistance to selected antibiotics and Panton-Valentine leukocidin-positive Staphylococcus aureus in a healthy student population at a Malaysian University

Introduction

This study aims to assess the antimicrobial susceptibility profiles of Staphylococcus aureus strains isolated from university students and to determine the prevalence of constitutive and inducible clindamycin resistance, the latter being able to cause therapeutic failure due to false in vitro clindamycin susceptibility.

Methods

S. aureus strains were isolated from the nasal swabs of 200 health sciences students of a Malaysian university. Twelve classes of antibiotics were used to evaluate the antimicrobial susceptibility profiles with the macrolide-lincosamide-streptogramin B (MLS_B) phenotype for inducible clindamycin resistance determined by the double-diffusion test (D-test). Carriage of resistance and virulence genes was performed by PCR on S. aureus isolates that were methicillin resistant, erythromycin resistant and/or positive for the leukocidin gene, pvl (n=15).

Results

Forty-nine isolates were viable and identified as S. aureus with four of the isolates characterized as methicillin-resistant S. aureus (MRSA; 2.0%). All isolates were susceptible to the antibiotics tested except for penicillin (resistance rate of 49%), erythromycin (16%), oxacillin (8%), cefoxitin (8%) and clindamycin (4%). Of the eight erythromycin-resistant isolates, iMLS_B was identified in five isolates (three of which were also MRSA). The majority of the erythromycin-resistant isolates harbored the msrA gene (four iMLS_B) with the remaining iMLS_B isolate harboring the ermC gene.

Conclusion

The presence of MRSA isolates which are also iMLS_B in healthy individuals suggests that nasal carriage may play a role as a potential reservoir for the transmission of these pathogens.

A Novel erm(44) Gene Variant from a Human Staphylococcus saprophyticus Isolate Confers Resistance to Macrolides and Lincosamides but Not Streptogramins

A novel erm(44) gene variant, erm(44)_v, has been identified by whole-genome sequencing in a Staphylococcus saprophyticus isolate from the skin of a healthy person. It has the particularity to confer resistance to macrolides and lincosamides but not to streptogramin B when expressed in S. aureus The erm(44)_v gene resides on a 19,400-bp genomic island which contains phage-associated proteins and is integrated into the chromosome of S. saprophyticus.

The Rate of Inducible MLSB Resistance in the Methicillin-Resistant Staphylococci Isolated From Clinical Samples

BACKGROUND

Staphylococci are one of the most common pathogens in nasocomial and community-acquired infections. Methicillin-resistant staphylococci are known to be resistant against all beta-lactam antibiotics. Therefore, non-beta-lactam antibiotics such as macrolide and lincosamides can be used. Resistance to those antibiotics may lead to therapeutic failure. The purpose of the present study was to determine the prevalence of macrolide-lincosamide-streptogramin B (MLSB ) resistance by using D-test in staphylococcal isolates from various clinical samples.

METHODS

Seventy-one methicillin-resistant Staphylococcus isolates (six S. aureus, 65 coagulase negative staphylococci) were included in this study. Staphylococci were identified with conventional methods. According to Clinical Laboratory Standards Institute (CLSI) criteria, susceptibility testing was performed by Kirby-Bauer disk diffusion method.

RESULTS

One of six (16.6%) methicillin-resistant S. aureus isolates and 19 of 65 (29.2%) methicillin-resistant coagulase-negative staphylococci (MR-CNS) were detected as D-test positive. Twenty of 71 (28.1%) staphylococcal isolates detected as D-test positive. Inducible clindamycin resistance was found at a higher rate in MR-CNS.

CONCLUSION

Since the resistant community and hospital acquired staphylococcal infections have become a therapeutic problem, it is very important to detect MLSB resistance routinely in microbiology laboratories. D-test is a cheap and reliable diagnostic method that can be performed in every laboratory.

The prevalence of inducible and constitutive clindamycin resistance among the nasal isolates of staphylococci

CONTEXT

One of the important sources of Staphylococci which causes nosocomial infections, is the nasal carriage of Staphylococci among Health Care Workers (HCWs). The commonest antibiotic which is preferred for the treatment of the methicillin and multi drug resistant Staphylococcal infections is clindamycin. The inducible clindamycin resistance in Staphylococci is not detected by the routine antibiotic susceptibility testing and it results in treatment failures.

AIM

The present study was undertaken to know the prevalence of constitutive and inducible clindamycin resistance and its correlation with the methicillin resistance among the nasal isolates of Staphylococci which were obtained from different HCWs.

MATERIAL AND METHODS

Nasal swabs were collected from 206 HCWs and they were processed. The Staphylococci which were isolated were tested for methicillin resistance by using cefoxitin (30 μg) discs. The inducible clindamycin resistance was tested by using erythromycin (15 μg) and clindamycin (2μg) discs and the D test according to the CLSI guidelines.

RESULTS

Inducible clindamycin resistance was seen in 21(16.40%) of the S.aureus and 14 (7.56%) of the coagulase negative Staphylococcal isolates. Constitutive clindamycin resistance was seen in 23(17.96%) of the S.aureus and 43(23.24%) of the coagulase negative Staphylococcal isolates. The inducible and constitutive clindamycin resistance was more common among the methicillin resistant Staphylococcal isolates.

CONCLUSION

The prevalence of inducible and constitutive clindamycin resistance in the nasal Staphylococcal isolates which were obtained from the HCWs was high, especially among the methicillin resistant Staphylococci. The D test which is recommended by the CLSI should be routinely done to detect inducible clindamycin resistance, to prevent treatment failures.