Minimum Inhibitory Concentrations Of Clindamycin Research Articles

Antibiotic potentiating effect of Bauhinia purpurea L. against multidrug resistant Staphylococcus aureus.

Bauhinia purpurea L. is a medium-sized tree from the family Fabaceae. The plant is traditionally used as medicine by different tribes in Sikkim. The present study aimed to evaluate the modulation in minimum inhibitory concentration (MIC) of the bark methanol extract of Bauhinia purpurea L. against the clinical isolates of multidrug resistant Staphylococcus aureus. The synergistic activity of the test plant extract with different classes of antibiotics was also evaluated. The methanol extract of Bauhinia purpurea exhibited modulation by a 16-fold reduction in the MIC of clindamycin against both resistant and susceptible isolates, followed by penicillin and gentamicin, whereas a maximum of only a 4-fold MIC reduction was observed with ciprofloxacin. The lowest minimum inhibitory concentration and minimum bactericidal concentration showed by the plant extract was 0.48 and 0.97 mg/mL, respectively. The methanol extract of Bauhinia purpurea exhibited synergistic activity with penicillin, gentamicin, ciprofloxacin, and clindamycin against most of the tested isolates of multidrug-resistant Staphylococcus aureus (MDR-SA). Gas chromatography-mass spectrometry analysis of Bauhinia purpurea L. bark methanol extract revealed 16 phytocompounds. The results provide an insight into the potential antibacterial property of the plant extract in terms of its antibiotic MIC modulation and synergistic properties with the selected antibiotics. This is the first report of the antibiotic potentiation property of Bauhinia purpurea L., collected from Sikkim, India.

Discovery of a Novel Integrative Conjugative Element ICEAplChn2 Related to SXT/R391 in Actinobacillus pleuropneumoniae.

Objective: The objective of this study was to characterize ICEAplChn2, a novel SXT/R391-related integration and conjugation element (ICE) carrying 19 drug resistance genes, in a clinical isolate of Actinobacillus pleuropneumoniae from swine. Methods: Whole genome sequencing (WGS) of A. pleuropneumoniae CP063424 strain was completed using a combination of third-generation PacBio and second-generation Illumina. The putative ICE was predicted by the online tool ICEfinder. ICEAplChn2 was analyzed by PCR, conjugation experiments, and bioinformatics tools. Results: A. pleuropneumoniae CP063424 strain exhibited high minimum inhibitory concentrations of clindamycin (1,024 mg/L). The WGS data revealed that ICEAplChn2, with a length of 167,870 bp and encoding 151 genes, including multiple antibiotic resistance genes such as erm(42), VanE, LpxC, dfrA1, golS, aadA3, EreA, dfrA32, tetR(C), tet(C), sul2, aph(3)″-lb, aph(6)-l, floR, dfrA, ANT(3″)-IIa, catB11, and VanRE, was found to be related to the SXT/R391 family on the chromosome of A. pleuronipneumoniae CP063424. The circular intermediate of ICEAplChn2 was detected by PCR, but conjugation experiments showed that it was not self-transmissible. Conclusions: To our knowledge, ICEAplChn2 is the longest member with the most resistance genes in the SXT/R391 family. Meanwhile, ATP-binding cassette superfamily was found to be inserted in the ICEAplChn2 and possessed a new insertion region, which is the first description in the SXT/R391 family.

First Report of Oxacillin Susceptible mecA-Positive Staphylococcus aureus in a Children's Hospital in Kunming, China.

PurposeThe present study investigated the prevalence characteristics of oxacillin susceptible mecA-positive Staphylococcus aureus (OS-MRSA) in a children’s hospital in Kunming from January 2019 to December 2020.MethodsA total of 499 S. aureus strains were included in the study and tested for oxacillin susceptibility using the VITEK 2 Compact automated antimicrobial susceptibility test system. All oxacillin-susceptible strains were detected mecA and mecC by polymerase chain reaction (PCR). E-test was used to compare the minimum inhibitory concentration (MIC) values of methicillin-susceptible S. aureus (MSSA), methicillin-resistant S. aureus (MRSA), and OS-MRSA for oxacillin, cefoxitin, penicillin, vancomycin, erythromycin, and clindamycin. Molecular typing of OS-MRSA was performed by MLST and SCCmec typing. Toxin genes were detected by PCR.ResultsForty-five OS-MRSA strains were detected, for an overall rate of 9.02% (45/499). The MICs of MSSA, OS-MRSA, and MRSA against oxacillin were concentrated at 0.38, 0.38, and 12 μg/mL, respectively; the cefoxitin MICs of MSSA and MRSA were concentrated at 2 and 32 μg/mL respectively; and MICs of OS-MRSA were concentrated at 2 and 8 μg/mL; penicillin, vancomycin and erythromycin MICs against MSSA, OS-MRSA, and MRSA showed same centralized points and were 32, 1, and 256 μg/mL, respectively; the MICs of clindamycin against MSSA were 0.5 μg/mL, while that against OS-MRSA and MRSA were concentrated at 256 μg/mL. Molecular typing of OS-MRSA was dominated by ST59-SCCmec IV. The carrier rates of hemolysin genes (hl-a, hl-d) and fibrinogen-binding clumping factor genes (clfA, clfB) were 100% in OS-MRSA, followed by 40% (18/45) for enterotoxin genes (sea, seb).ConclusionOS-MRSA has a high detection rate in children, and main molecular typing is ST59-SCCmecIV in Kunming. The identification ability of automated antibacterial drug sensitivity test detection systems for OS-MRSA is very limited. A combination of phenotypic analysis and molecular detection should be used to improve OS-MRSA identification.

Antimicrobial Susceptibility Testing of Metronidazole and Clindamycin against Gardnerella vaginalis in Planktonic and Biofilm Formation.

Background Bacterial vaginosis (BV), one of the most common vaginal ecosystem-related microbiologic syndromes, is the most common disorder in women of reproductive age. Gardnerella (G.) vaginalis is the predominant species causing this infection. Our aim was to compare the antimicrobial susceptibilities of metronidazole and clindamycin against G. vaginalis at planktonic and biofilm levels. Methods From September 2019 to October 2019, we recruited a total of 10 patients with BV who underwent gynecological examinations at Beijing Obstetrics and Gynecology Hospital. G. vaginalis isolates were obtained from the vagina and identified using their characteristic colony morphology. Sequence data of clinical G. vaginalis isolates were confirmed by comparing 16S rDNA sequences. Subsequently, clinical isolates were evaluated for antimicrobial susceptibilities in vitro to metronidazole and clindamycin at planktonic and biofilm levels. The minimum inhibitory concentration (MIC) for metronidazole and clindamycin was evaluated by antimicrobial susceptibility testing. The minimum biofilm eradication concentration (MBEC) was evaluated by the biofilm inhibition assay. Results Planktonic clinical isolates showed a significantly higher susceptibility rate (76.67%) and lower resistance rate (23.33%) to clindamycin than to metronidazole (susceptibility rate: 38.24%; resistance rate: 58.82%; P < 0.05 for both). Furthermore, in comparison to planktonic isolates, the minimum inhibitory concentration (MIC) of metronidazole was significantly higher for biofilm-forming isolates (7.3 ± 2.6 μg/mL vs. 72.4 ± 18.3 μg/mL; P=0.005); the resistance rate was 27.3%, and the minimum biofilm eradication concentration (MBEC) was >128 μg/mL. Moreover, the MIC of clindamycin was higher too for biofilm-forming isolates (0.099 ± 0.041 μg/mL vs. 23.7 ± 9.49 μg/mL; P=0.034); the resistance rate was 27.3%, and the MBEC of clindamycin was 28.4 ± 6.50 μg/mL. Conclusion Our results indicate that in comparison to metronidazole, clindamycin seems to be a better choice to tackle G. vaginalis as it exhibits a relatively higher susceptibility rate and lower resistance rate.

Assessment of Efficacy and Safety of Clindamycin Against Methicillin- Resistant Staphylococcus aureus (MRSA) Infected Subcutaneous Abscess Model

Background: Methicillin-resistant Staphylococcus aureus (MRSA) causes infection in the wound leading to life-threatening bacteriemia. It causes recalcitrant infections because of being resistant to various antibiotics. The recent studies reported clindamycin to be effective against MRSA rather than inducible clindamycin resistance and decrease the incidence of new infections after clindamycin treatment. The study focused on assessing the efficacy and safety of clindamycin against MRSA infected rats. Methods: The rats become neutropenic by intraperitoneal administration of cyclophosphamide at a dose of 150 mg/kg and 100 mg/kg for 4 days and 5th day respectively. The neutropenic rats were infected with MRSA by subcutaneous administration of 106 CFU/ml of MRSA. The 3 groups of rats such as Normal, MRSA infected, MRSA infected rats that were administered clindamycin orally at a dose of 90 mg/kg/ thrice daily for 14 days were used in the study. The abscess size, weight, and bacterial load were measured at the end of the study. The blood and liver samples were collected for biochemical analysis and histopathological evaluation. Results: The MRSA was confirmed by Polymerase Chain Reaction (PCR) method. The clindamycin minimum inhibitory concentration was 0.125 - 0.5 μg/ml. The MRSA showed negative D test for clindamycin indicating the absence of inducible clindamycin resistance. The decreased abscess size, weight, bacterial count, Intestinal Alkaline Phosphatase (IAP), weight loss, alteration in hematological parameters, mild changes in cholesterol, ALT and liver histology, no significant (P &gt; 0.05) change in triglycerides, AST, ALP, bilirubin, lactate, urea, and creatinine were seen in clindamycin treated MRSA infected rats. The MRSA infected clindamycin treated rats showed mild irritation and diarrhea. Conclusion: Our study concludes that the clindamycin showed better anti- MRSA activity and tolerable adverse effects such as anemia, weight loss, and mild irritation after oral treatment, but the intestinal dysbiosis is a severe adverse effect and causes diarrhea.

Two genes involved in clindamycin resistance of Bacillus licheniformis and Bacillus paralicheniformis identified by comparative genomic analysis.

We evaluated the minimum inhibitory concentrations of clindamycin and erythromycin toward 98 Bacillus licheniformis strains isolated from several types of fermented soybean foods manufactured in several districts of Korea. First, based on recent taxonomic standards for bacteria, the 98 strains were separated into 74 B. licheniformis strains and 24 B. paralicheniformis strains. Both species exhibited profiles of erythromycin resistance as an acquired characteristic. B. licheniformis strains exhibited acquired clindamycin resistance, while B. paralicheniformis strains showed unimodal clindamycin resistance, indicating an intrinsic characteristic. Comparative genomic analysis of five strains showing three different patterns of clindamycin and erythromycin resistance identified 23S rRNA (adenine 2058-N6)-dimethyltransferase gene ermC and spermidine acetyltransferase gene speG as candidates potentially involved in clindamycin resistance. Functional analysis of these genes using B. subtilis as a host showed that ermC contributes to cross-resistance to clindamycin and erythromycin, and speG confers resistance to clindamycin. ermC is located in the chromosomes of strains showing clindamycin and erythromycin resistance and no transposable element was identified in its flanking regions. The acquisition of ermC might be attributable to a homologous recombination. speG was identified in not only the five genome-analyzed strains but also eight strains randomly selected from the 98 test strains, and deletions in the structural gene or putative promoter region caused clindamycin sensitivity, which supports the finding that the clindamycin resistance of Bacillus species is an intrinsic property.

A novel resistance gene, lnu(H), conferring resistance to lincosamides in Riemerella anatipestifer CH-2

The Gram-negative bacterium Riemerella anatipestifer CH-2 is resistant to lincosamides, having a lincomycin (LCM) minimum inhibitory concentration (MIC) of 128 µg/mL. The G148_1775 gene of R. anatipestifer CH-2, designated lnu(H), encodes a 260-amino acid protein with ≤41% identity to other reported lincosamide nucleotidylyltransferases. Escherichia coli RosettaTM (DE3) containing the pBAD24-lnu(H) plasmid showed four- and two-fold increases in the MICs of LCM and clindamycin (CLI), respectively. A kinetic assay of the purified Lnu(H) enzyme for LCM and CLI showed that the protein could inactive lincosamides. Mass spectrometry analysis demonstrated that the Lnu(H) enzyme catalysed adenylylation of lincosamides. In addition, an lnu(H) gene deletion strain exhibited 512- and 32-fold decreases in LCM and CLI MICs, respectively. The wild-type level of lincosamide resistance could be restored by complementation with a shuttle plasmid carrying the lnu(H) gene. The transformant R. anatipestifer ATCC 11845 [lnu(H)] acquired by natural transformation also exhibited high-level lincosamide resistance. Moreover, among 175 R. anatipestifer field isolates, 56 (32.0%) were positive for the lnu(H) gene by PCR. In conclusion, Lnu(H) is a novel lincosamide nucleotidylyltransferase that inactivates LCM and CLI by nucleotidylylation, thus conferring high-level lincosamide resistance to R. anatipestifer CH-2.

Phenotypic and Genotypic Characterization of Multidrug-ResistantBacteroides,Parabacteroidesspp., andPseudoflavonifractorfrom a Costa Rican Hospital

Multidrug resistance in Bacteroides spp. and related genera is uncommon and has not been described in Latin America until now. We studied phenotypically and genotypically the multidrug resistance of 10 clinical strains of Bacteroides, two of Parabacteroides distasonis, and one of Pseudoflavonifractor capillosus recovered in a national hospital between 2006 and 2010. To this end, we determined minimum inhibitory concentrations (MICs) of amoxicillin, amoxicillin-clavulanic acid, cefotaxime, imipenem, clindamycin, ciprofloxacin, tetracycline, and metronidazole using E-tests, evaluated the isolates for β-lactamases with nitrocefin hydrolysis tests, performed a polymerase chain reaction (PCR)-based screening of erm, tet, and nim genes, obtained partial gyrA sequences, and studied the effect of tazobactam and efflux pump inhibitors (EPI) on the MIC of cefotaxime, clindamycin, and ciprofloxacin. Three isolates were resistant to four different classes of antibiotics and 10 were resistant to three. β-lactam resistance was in most cases due to β-lactamases susceptible of partial inhibition by tazobactam. Ten isolates were cfxA-positive and two isolates had cepA. Twelve isolates were highly resistant to clindamycin and nine were highly resistant to ciprofloxacin. However, these phenotypes were not linked to ermA, ermB, ermF, and ermG or mutations in gyrA. Addition of EPI lowered the MICs of clindamycin and ciprofloxacin of one and four isolates, respectively. Twelve isolates had tetQ and four were positive for tetM. In both cases, genes of the two-component system RteAB accompanied tet genes. Although metronidazole susceptibility was universal, nim genes were not present. To our knowledge, this is the first report of multidrug resistance due to less commonly identified or alternative mechanisms in strains of Bacteroides and related species from a developing country.

Clinical characteristics of infections caused by Tsukamurella spp. and antimicrobial susceptibilities of the isolates

To investigate the clinical and microbiological characteristics of infections caused by Tsukamurella spp., the computerised database of the Bacteriology Laboratory at National Taiwan University Hospital (Taipei, Taiwan) was reviewed retrospectively to identify patients with infections caused by this species during the period January 1997 to December 2008. All of the isolates had been initially misidentified as Rhodococcus spp. Identification of Tsukamurella isolates to species level was carried out by polymerase chain reaction–restriction fragment length polymorphism (PCR-RFLP) analysis of the heat shock protein gene ( hsp65) as well as 16S rRNA gene sequencing. During the study period, a total of eight patients with Tsukamurella infection and two patients with Tsukamurella colonisation were identified. Tsukamurella tyrosinosolvens ( n = 6) was the most prevalent species, followed by Tsukamurella spumae ( n = 3) and Tsukamurella pulmonis ( n = 1). Keratitis was the most common type of infection ( n = 3), followed by catheter-related bloodstream infection ( n = 2). One of the patients with Tsukamurella infection died due to bacteraemia; the other seven patients with Tsukamurella infection had favourable outcomes. The three species had different drug susceptibility patterns; T. pulmonis was the most resistant pathogen, with higher minimum inhibitory concentrations of clindamycin (>2 mg/L), erythromycin (2 mg/L) and tetracycline (8 mg/L) than those for the other Tsukamurella spp. In conclusion, strains of Tsukamurella spp., including T. spumae, are uncommon causative agents of ocular infections and bacteraemia in cancer patients. Molecular diagnostic methods are essential to distinguish species in the Tsukamurella genus from species in other phylogenetically related genera such as Rhodococcus.

Trans‐Cinnamaldehyde from Cinnamomum zeylanicum Bark Essential Oil Reduces the Clindamycin Resistance of Clostridium difficile in vitro

Therapy with antimicrobial drugs, such as clindamycin, that perturb the intestinal flora but fail to inhibit growth of other microorganisms can permit the proliferation of Clostridium difficile and the elaboration of exotoxin. Therefore, there has been increasing interest in the use of inhibitors of antibiotic resistance for use in combination therapy. The essential oil of Cinnamomum zeylanicum bark enhanced the bactericidal activity of clindamycin and decreased the minimum inhibitory concentration of clindamycin required for a toxicogenic strain of C. difficile. Thin-layer chromatography (TLC) analysis of the essential oil separated a fraction (R(f) = 0.54) that was the most effective at enhancing the clindamycin antimicrobial activity. Using gas liquid chromatography and known standards, the active fraction was identified as trans-cinnamaldehyde (3-phenyl-2-Propenal). Combinations of clindamycin and trans-cinnamaldehyde were tested to determine the fractional inhibitory concentration (FIC) index by conventional checkerboard titration. The FIC index for C. difficile was found to be 0.312, which confirmed the synergistic actions of clindamycin and trans-cinnamaldehyde. The presence of 20 microg/mL of trans-cinnamaldehyde decreased the MIC of clindamycin for C. difficile 16-fold, from 4.0 to 0.25 microg/mL. These results signify that low concentrations of trans-cinnamaldehyde elevate the antimicrobial action of clindamycin, suggesting a possible clinical benefit for utilizing these natural products for combination therapy against C. difficile.

Susceptibility of pathogenic actinomycetes to antimicrobial compounds.

Current interest in antimicrobial susceptibility testing of anaerobic pathogens and recent recognition that actinomycetes other than Actinomyces israelii may cause actinomycosis in man prompted this in vitro survey of 74 strains of actinomycetes, representing seven species. Minimum inhibitory concentrations (MICs) for 24 antimicrobials were determined by inhibition of gross colonial enlargement in semisolid antibiotic agar after incubation at 37 C for 48 h under anaerobic conditions. Erythromycin and rifampin were the most active drugs in vitro (MICs of 0.008 to 0.25 mug/ml), although a small number of non-israelii strains were conspicuously more resistant to the latter (MICs >0.5 mug/ml). Penicillin G, cephaloridine, minocycline, and clindamycin were also very active in vitro (MICs of 0.03 to 1.0 mug/ml); for a few non-israelii strains the MICs of clindamycin were 2.0 to 8.0 mug/ml. MICs of cephalothin, ampicillin, lincomycin, tetracycline, doxycycline, and chloramphenicol were well within a therapeutic range for all strains of A. israelii and most other species, although the MIC of lincomycin against a few non-israelii strains and of tetracycline and doxycycline against the majority of these strains was 2.0 to 8.0 mug/ml. Oxacillin, dicloxacillin, and cephalexin were less active in vitro, particularly against strains other than A. israelii. Most non-israelii species were not suppressed by 125 mug of metronidazole per ml, which concentration inhibited all strains of A. israelii; otherwise, there were no antimicrobial susceptibility differences among the species tested. Aminoglycoside activity was negligible.