Constitutive Clindamycin Resistance Research Articles

Characterization of biofilm formation in uropathogenic Staphylococcus aureus and their association with antibiotic resistance

IntroductionThe increase in antibiotic resistance and biofilm formation in Staphylococcus aureus is a serious public health problem, complicating the treatment of infections caused by these bacteria, including urinary tract infections (UTIs). This research aimed to assess the correlation between antibiotic resistance and the capacity for biofilm formation in S. aureus strains isolated from patients with UTIs. MethodsThe antibiotic susceptibility testing was conducted using disc diffusion and broth micro-dilution method. The blaZ and mecA genes were investigated in all penicillin and cefoxitin-resistant S. aureus strains, using PCR. Biofilm formation was investigated using the Congo red agar and microtitre plate methods. All S. aureus strains were screened for genes encoding adhesion and biofilm formation (spa, fnb AB, clfA, bap) and intercellular adhesin (icaADB and icaR). ResultsAmong 20 strains of S. aureus, 55% were found to be multidrug-resistant (MDR) and methicillin-resistant (MRSA). All strains were biofilm producers, including 55% moderate biofilm producers and 35% strong biofilm producers. A significant correlation (p-value <0.01) was observed between MDR and non-MDR strains in terms of biofilm production. All strains were sensitive to linezolid, and 20% exhibited the constitutive clindamycin resistance phenotype. The spa, fnbB, and clfA genes were present in all strains followed by the bap (95%) and fnbA (90%). The icaA (90%) and icaB (60%) genes were most detected. The coexistence of icaA, icaADB, and icaAD genes was significantly associated with MRSA strains. In contrast, the icaR gene was significantly detectable in the methicillin-susceptible group of strains. ConclusionThis study uncovered a significant association between the formation of biofilms by uropathogenic S. aureus and antibiotic resistance, highlighting a noteworthy concern for public health.

Molecular Characteristics of Staphylococcus aureus Strains to Carry Panton-Valentine Leukocidin Genes Isolated from Hospitalized Patients in Tehran, Iran

Background: Staphylococcus aureus with concurrent resistance to antibacterial agents is emerging globally. This emergence might be due to the production of different virulence determinants, notably Panton-Valentine leukocidin (PVL). Objectives: This study aimed to investigate the genetic characteristics of PVL-positive S. aureus strains isolates from clinical samples. Methods: An epidemiological study was conducted on 65 S. aureus isolates carrying pvl genes. An antibiogram test by the disk diffusion and broth microdilution methods was conducted to assess antimicrobial resistance profiles. Results: All detected methicillin-resistant S. aureus (MRSA) isolates were confirmed by mecA polymerase chain reaction (PCR) assays. The PVL-positive isolates were characterized using multiplex PCR assay to detect staphylococcal cassette chromosome mec (SCCmec) and agr types. The PVL frequency was 19.5% and 17.6% in MRSA and methicillin-susceptible S. aureus (MSSA), respectively. Among the PVL-positive isolates, 66.2% and 33.8% were MRSA and MSSA, respectively. Multidrug resistance amounted to 84.6% of the isolates (MRSA: 61.5%, MSSA: 23.1%). Staphylococcal cassette chromosome mec III was dominated (55.8%; 24/43). The most commonly identified agr was type III (53.8%; 35/65). Resistance to vancomycin amounted to 12.3% of the isolates, and all belonged to agr type III and SCCmec type III. The frequency of inducible and constitutive clindamycin resistance among PVL-positive MRSA strains (12.3% and 26.1%) was higher than PVL-positive MSSA strains (7.7% and 15.4%). Most constitutive and inducible clindamycin resistance isolates belonged to agr type III (26.2% and 18.5%) and SCCmec type III (each 27.9%). In the present study, 32.3% of the isolates were confirmed as mupirocin resistant, and all were MRSA, 9 (42.9%) and 12 (57.1%) isolates of which exhibited high-level mupirocin resistant (HLMUPR) and low-level mupirocin resistant phenotypes. All HLMUPR MRSA isolates belonged to SCCmec III and recovered from wound samples. Conclusions: The emergence of vancomycin-resistant S. aureus strains among PVL-positive S. aureus strains in Iran is a serious alarm and seems to be becoming the greatest concern in the treatment of staphylococcal infections in the healthcare setting. The present study reinforces plausible direct transfers between community and nosocomial PVL-positive S. aureus types.

1321. Increased Prevalence of Group A Streptococcus (GAS) High Level Macrolide Resistance During the COVID-19 Pandemic

Abstract Background COVID-19 affected the epidemiology of many respiratory pathogens including GAS. Assessing genetic heterogeneity (emm type, antimicrobial resistance, virulence factors) can inform treatment recommendations and targets for potential GAS vaccines. We assessed GAS clinical antibiotic susceptibility and performed whole genome sequencing (WGS) among pediatric pharyngeal isolates from 2020–2022. Methods From 1/2020–3/2022 we collected throat swabs in pediatric clinics and EDs from children aged 3-18 years in Chicago, IL; Atlanta, GA; Portland, OR; and Phoenix, AZ: 1) with acute GAS pharyngitis and 2) among a convenience sample of asymptomatic children to assess for GAS colonization. Swabs were plated on blood agar. E-tests were used to assess clinical susceptibility to erythromycin (ERY) and ciprofloxacin (CIP). emm type and antimicrobial resistance genes (ERY, Clindamycin (CLI), and fluoroquinolones) were assessed by WGS. Results 1144 pharyngeal swabs were collected: 359/684 (52%) from children with GAS pharyngitis by rapid test and 20/460 (4.3%) from asymptomatic children yielded GAS on culture. Phenotypic resistance: 55/364 (15%) tested isolates were ERY resistant and 5/364 (1.4%) CIP resistant. The proportion of isolates with ERY resistance increased significantly from 2020 (6%) to 2021–2022 (25%) (χ2 = 23.70, p&amp;lt; .00001) (Figure 1). MICs were high among ERY resistant GAS (Table 1). Genotypic resistance: Of 304 sequenced GAS isolates 40/304 (13%) were ERY resistant, 35/304 (11.5%) were both ERY resistant and CLI (inducible or constitutive) resistant, and 4/304 (1.3%) fluoroquinolone resistant. ermB (62%) was the most common gene for ERY resistance and constitutive CLI resistance, followed by ermTR (23%) and ermT (11%) both conferring inducible CLI resistance. Among the 20 isolates from asymptomatic children no ERY, CLI, or CIP resistance occurred, and no resistance genes were identified. emm types 11, 9, 77, 58 and 94 were associated with ERY and CLI resistance. Conclusion ERY resistance increased from 2020–2022. The high rate of CLI resistance among ERY resistant GAS was associated with erm genes. These results are important to inform treatment recommendations for GAS pharyngitis and targets for vaccine development that can reduce antimicrobial-resistant GAS disease. Disclosures All Authors: No reported disclosures.

Prevalence of Constitutive and Inducible Clindamycin Resistance among Methicillin-Resistant Staphylococcus aureus Isolates in a Tertiary Care Hospital, Kashmir Valley

Prevalence of Constitutive and Inducible Clindamycin Resistance among Methicillin-Resistant Staphylococcus aureus Isolates in a Tertiary Care Hospital, Kashmir Valley

CHARACTERIZATION OF STAPHYLOCOCCUS AUREUS ISOLATED FROM BURN WOUND; STRONG ANTIBACTERIAL ACTIVITY OF PHAGE COCKTAIL AGAINST VANCOMYCIN INTERMEDIATE-RESISTANT STAPHYLOCOCCUS AUREUS

A universal problem is about spread of Staphylococcus aureus infections in burn patients. The present study aimed to learn about the molecular characteristics and the resistance pattern of S. aureus strains isolated from burn patients. In this cross-sectional study, we investigated 100 unique S. aureus isolated from burn patients by antimicrobial activity and biofilm formation and evaluated the effect of Complex Pyobacteriophage, a commercial bacteriophage cocktail, against the isolates mentioned above. Methicillin-resistant Staphylococcus aureus (MRSA) comprised 76%, and methicillin-susceptible Staphylococcus aureus (MSSA) comprised 24% of 100 S. aureus strains. The resistance rate among MRSA isolates was higher than compared of MSSA. Mupirocin resistance was found in 30% of isolates, with 28 (93.3%) and 2 (6.7%) strains of MRSA and MSSA, respectively, found. Vancomycin intermediate resistance in S. aureus (VISA) was 13% of MRSA strains. Two isolates were confirmed as vancomycin-resistant S. aureus (VRSA) strains and carried vanA. 31 and 62% of the total isolates showed inducible and constitutive resistance phenotypes. The rate of inducible and constitutive clindamycin resistance among MRSA strains was higher than MSSA strains. Biofilm production was detected in 66% of isolates. Strong, moderate, and weak producers accounted for 25%, 17%, and 24% of isolates. Phage analysis showed that 81% were susceptible to the phage cocktail, and only 19% were resistant to the phage cocktail. Our data indicated that VISA strains prevalence in the burn unit was mainly from S. aureus infections. Present work recommended that vancomycin treatment be closely monitored to prevent the spread of VISA and VRSA strains. Observations also highlighted the role of bacteriophage cocktails in eradicating S. aureus-related infections.

Constitutive and Inducible Clindamycin Resistance Frequencies among Staphylococcus sp. Coagulase Negative Isolates in Al-Basrah Governorate, Iraq.

Antibiotics called macrolide, lincosamide and streptogramin B (MLSB) are being used to treat staphylococci infections. Multiple pathways that impart resistance to MLSB antibiotics have been confirmed to cause clinical failure. The present work aimed to determine the frequency of constitutive and inducible clindamycin resistant among coagulase-negative staphylococci (CoNS) isolates of different clinical samples in Al-Basrah governorate, Iraq. The 28 CoNS, traditional techniques and the Vitek®2 system were used to identify the isolates. The disk diffusion technique was used to detect methicillin resistance and antibiotic sensitivity patterns via cefoxitin, gentamicin, ciprofloxacin, amikacin, teicoplanin, linezolid, doxycycline and vancomycin disks. Erythromycin and clindamycin antibiotic disks was used to detect the inducible and constitutive clindamycin resistance as well as a D-test according to CLSI guidelines. Among 28 CoNS isolated, the Staphylococcus aureus 11(39.29%), Staphylococcus epidermidis 7(25 %), Staphylococcus haemolyticus 4(14.29%) and Staphylococcus saprophyticus 3 (10.71%) were predominant isolated species. Out of 28 CoNS isolates, 15(53.57%) were methicillin resistant coagulase-negative staphylococci (MRCoNS) isolates and 13(46.43%) were methicillin sensitive coagulase-negative staphylococci (MSCoNS) isolates. The 15(53.57%) isolates out of 28 CoNS, showed erythromycin resistance while 6(40%) isolates out of 15 CoNS, showed inducible macrolide-lincosamide-streptogramin B (iMLSB) and 2(13.3%) of CONS isolated showed constitutive macrolide-lincosamide-streptogramin B (cMLSB). In order to achive the best result in choosing the suitable treatment and avoiding the loses the money and time, it is better to use the D-test for inducible clindamycin resistance in the daily routine work of antibiotic susceptibility testing in hospital and private clinical laboratories.

Inducible Clindamycin Resistant Staphylococcus aureus among Patients Attending Tertiary Care Centre: A Descriptive Cross-sectional Study.

Staphylococcus aureus, a superbug, resistant to multiple antibiotics led to growing interest in the usage of macrolide-lincosamide-streptogramin B antibiotics, which are now rapidly developing resistance. This study aims to find the prevalence of inducible clindamycin-resistant Staphylococcus aureus among obtained clinical samples from in-patient and out-patient departments of a tertiary care center. This is a descriptive cross-sectional study done in clinical samples from the in-patient and out-patient departments of a tertiary care center from September 2020-May 2021. Ethical clearance was taken from the Institutional Review Committee (Ref: 068/2077/2078). Staphylococcus aureus were isolated and antibiotic susceptibility tests were performed by disc diffusion method. Inducible clindamycin and methicillin resistance Staphylococcus aureus were detected using D-test and cefoxitin disc according to Clinical and Laboratory Standards Institute guidelines. Convenient sampling was done and the data was analyzed using Statistical Package for Social Sciences version 20. Point estimate at 95% confidence interval was calculated along with frequency and proportion for binary data. Among a total of 141 Staphylococcus aureus isolated, the prevalence of inducible clindamycin resistant phenotype was 41 (29.1%) (21.6-36.59 at 95% Confidence Interval). Whereas, 30 (21.3%) were constitutive clindamycin resistant. The inducible 28 (47.5%) and 19 (32.2%) constitutive clindamycin resistance was higher among methicillin-resistant Staphylococcus aureus. The frequency of inducible clindamycin resistance among methicillin resistant Staphylococcus aureus was high, which alarms the use of macrolide-lincosamide-streptogramin B antibiotics in Staphylococcus aureus infections. Hence, D-test should be performed to detect inducible clindamycin resistance in routine testing to prevent treatment failure.

Frequency and Sensitivity Patterns of Staphylococcus Aureus in a Tertiary Care Setting

Background: Staphylococcus aureus (SA) is a major etiological pathogen causing multiple infections and broadly known as a serious public health challenge faced due to antibiotic resistance. It is the need of time that infection prevention and control strategies; and antibiotic stewardship policies have to be employed conjointly to minimize the extended rise of antibiotic resistance.&#x0D; Objectives: To determine the frequency and sensitivity patterns of Staphylococcus aureus in tertiary care setting.&#x0D; Study Design: Descriptive study&#x0D; Place &amp; Duration of Study: Pathology Laboratory of tertiary care center from 1st March’ 2020 till 28th February’ 2021.&#x0D; Materials &amp; Methods: A total 643 Staph. aureus isolated from various clinical specimens received in a tertiary care hospital; were processed and identified by culture, staining and bench tests. Sensitivity testing was done by Disc Diffusion method. Resistance to cefoxitin(30µg) was labelled as Methicillin Resistant Staphylococcus aureus (MRSA). Constitutive and Inducible Clindamycin resistance was also evaluated. (CLSI, 2020-21).&#x0D; Results: During the study period 125 (19.44%) MRSA were recovered. Statistically, gender distribution regarding MRSA was significant, most of SA was recovered from blood (53.68%), while 46.31% from pus and wound swabs. The frequency of MRSA from Surgical and allied wards was higher (52.63%) than Medicine and allied wards (47.36%). Sensitivity to vancomycin, linezolid and tigecycline was noted 100% by all the isolates. Sensitivity to clindamycin and Doxycycline was 68.42% and 64.81% respectively; while resistance to erythromycin, ciprofloxacin and trimethoprim/sulfamethoxazole was 73.68%, 60% and 57.89%, respectively.&#x0D; Conclusion: The hazardous infections due to Staphylococcus aureus are worrisome in the present therapeutic scenario. A levelheaded prescription of sensitive antibiotics has to be ensured to minimize the rising frequency of resistant strains of SA.

Phenotypic characterization and Molecular detection of Inducible and Constitutive Clindamycin resistance among Staphylococcus aureus isolates in a Tertiary Care Hospital

Background: Staphylococcus aureus is Gram positive cocci. The pyogenic bacteria which is responsible for a variety of diseases that ranges in severity from mild skin and soft tissue infections to life-threatening conditions such as endocarditis, pneumonia, and sepsis. There is a scenario of increasing Methicillin-resistant Staphylococcus aureus (MRSA) infections, the macrolide-lincosamide-streptogramin B (MLSB) group of antibiotics they have different structure with same mechanism of action which serves as one good alternative. There is a frequency of increasing Methicillin Resistant Staphylococcus aureus (MRSA) infections and their change in antimicrobial resistance pattern. There is a concern about use of this antibiotic in the presence of Erythromycin resistance because of the possibility of inducible resistance among the members of Macrolide, lincosamide, Strepto-gramin B (MLSB) group. The invitro resistance exhibited by Staphylococcus aureus to erythromycin, Clindamycin, and other drugs of MLSB groups is due to the expression of ribosomal methylases(erm) genes. The detection of inducible Clindamycin resistance can limit the effectiveness of these drugs. Objective of the study: To isolate of Staphylococcus aureus from various clinical samples to differentiate between Methicillin resistant Staphylococcus aureus (MRSA) and Methicillin sensitive Staphylococcus aureus (MSSA) by conventional methods. To detect inducible and constitutive Clindamycin resistance in Staphylococcus aureus isolates by D test. To detect ermA gene responsible for resistance by PCR. Methodology: This cross sectional study was done for a period of six months. Totally 106 Staphylococcus aureus isolates was obtained various clinical samples were processed using standard guidelines. Result: From the 106 isolates of Staphylococcus aureus 67(63.3%) were MSSA and 39(36.7%) were MRSA. D-test was positive in n=9 of the n=21 MRSA and n=17 of the n=85 MSSA, which denotes inducible Clindamycin resistance. N- 9 of MRSA and n=13(22%) of MSSA showed Constitutional Clindamycin resistance. The statistics show that there is a significant Difference in constitutive resistance between MRSA and MSSA. In India ermA gene is most prevalent, out of 22 d-test positive n=13 ermA gene were detected (n=3-MRSA and n=10-MSSA) by using conventional PCR. Conclusion: The MLSB family of antibiotics is one such alternative and CD is preferred. Clinical microbiology laboratories should report inducible Clindamycin resistance in Staphylococcus aureus and D-test can be used as a simple, auxiliary and reliable method to Delineate inducible and constitutive Clindamycin resistance in routine clinical laboratories.

Plausible challenges of methicillin and clindamycin resistance detection in Staphylococcus aureus

Accurate detection and therapeutic challenges are still on the debate for methicillin-resistant Staphylococcus aureus (MRSA). Working on clindamycin, researchers serendipitously spotted the D test and the era of macrolide-lincosamide (ML) resistance commenced. We aimed to i) assess usage of other antibiotics other than cefoxitin for the detection of MRSA, ii) evaluate various surrogate therapeutic options, and iii) determine phenotypic and genotypic aspects of inducible and constitutive clindamycin resistance in S. aureus. Disk diffusion agar assay and molecular method were used to assess MRSA detection. Efficacy of linezolid, vancomycin, mupirocin, teicoplanin, fusidic acid, and rifampin was analyzed by E-test. Various phenotypes of macrolide-lincosamide-streptogramin B (MLSB) resistance were detected by performing D-test followed by PCR assay for ermA, ermB and ermC genes coding for macrolide resistance. The cefoxitin disc yielded the best sensitivity value (100%) over oxacillin, imipenem, and meropenem. All isolates were completely sensitive to linezolid and teicoplanin. Among MRSA isolates, 6.2%, 1.5%, and 17.1% strains had intermediate and complete resistance to vancomycin, fusidic acid, and rifampin respectively. Fifty-six isolates were clindamycin susceptible and diverse resistance outlooks were the major outcome of our study with 20.6% isolates demonstrated two distinct induction phenotypes (D and D+) and 45% isolates showed non-induction (HD,R) phenotypes. ermA gene alone and in combination with ermC was found to be more prevalent among inducible as well as constitutive clindamycin- resistant isolates.

Prevalence of Inducible Clindamycin Resistance in Staphylococcus: A Study from a Rural Teaching Tertiary Care Hospital in Southern Haryana

Introduction: Clindamycin is the most commonly prescribed Macrolides, Lincosamides and Streptogramin-B (MLSB) antibiotics to treat staphylococcal infections. It has excellent pharmacokinetic properties. Staphylococcus species shows either constitutive (MLSBc) or inducible (MLSBi) clindamycin resistance. Routine D-test recommended by Clinical Laboratory and Standard Institute (CLSI) can detect MLSBi phenotype and prevent treatment failure. Aim: To identify inducible clindamycin resistance in Staphylococci in a rural teaching Tertiary Care Hospital. Materials and Methods: It was a prospective, cross-sectional study. The clinical samples were cultured on blood agar and MacConkey agar. Staphylococcus isolates were identified based on their colony characteristics, gram stain and standard biochemical test. Antimicrobial susceptibility test was performed by Kirby Bauer’s disc diffusion method. To detect Methicillin resistance Cefoxitin disc (30 μg) was used. The isolates that were Erythromycin resistant and Clindamycin sensitive were further subjected to D test. CLSI 2019 guidelines were followed for performing the tests and its interpretation. Epi-info (version 7.2.3.1) Centre for Disease Control and Prevention (CDC), Atlanta, Georgia was used to analyse the data and interpretation of the results. Results: Total 150 Staphylococci were isolated from different samples. Staphylococcus aureus were 70% and Coagulase negative Staphylococcus (CoNS) were 30%. Pus was the most common specimen from which 43% Staphylococci was isolated. Sensitivity to vancomycin and linezolid were 100%. Staphylococcus aureus (38%) and CoNS (33%) were Methicillin resistant. Overall (63%) of staphylococcus isolates were resistant to erythromycin. The different susceptibility patterns to clindamycin in both Staphylococcus aureus and CoNS were noted. MLSBc phenotype was most prevalent (37.3%) followed by MS (13.4%) and MLSBi (12%) among erythromycin resistant Staphylococcus isolate. Sensitive (S) phenotype was detected in 56 (37%). MLSBi was more frequent in Methicillin Resistant Staphylococcus aureus (MRSA) (23%) and MRCoNS (27%) than in MSSA (5%) and MSCoNS (7%). Conclusion: D-test should be performed routinely to avoid false susceptible results leading to treatment failure.

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

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

Inducible and constitutive clindamycin resistance in Staphylococcus aureus, isolated from clinical samples

The resistance to antimicrobial agents among Staphylococci is an increasing problem. Clinical laboratories should perform D test routinely to guide the clinicians about the inducible clindamycin resistance and to prevent misuse of antibiotics. Study aimed to isolates the Inducible and Constitutive clindamycin Resistance in Staphylococcus aureus in various clinical samples. We analyzed the performance of disk diffusion method in 183 Staphylococci aureus strains obtained from various clinical samples of the patients collected from September 2018 to February 2020 at a tertiary care centre, Meerut. Inducible clindamycin resistance was tested by ‘D test’ as per CLSI guidelines. 142(77.6%) of isolates were found to be methicillin resistant (MRSA) and 41 (22.4%) tested sensitive to cefoxitin i.e., methicillin sensitive (MSSA). Inducible resistance and constitutive resistance were found to be higher in MRSA as compared to MSSA). The D test method showed to be simple and easy in the detection of inducible (iMLS) and constitutive clindamycin resistance (cMLS).

Molecular Characterization, Drug Resistance and Virulence Analysis of Constitutive and Inducible Clindamycin Resistance Staphylococcus aureus Strains Recovered from Clinical Samples, Tehran-Iran.

BackgroundMacrolide-lincosamide streptogramin B family is one of the important alternative antibiotics for treating staphylococcal infections. The aim of this study was to determine the characteristics and prevalence of antibiotic resistance genes in different coagulase types of clinical Staphylococcus aureus strains.MethodsIn the present study, 86 isolates with different phenotypes of MLSB resistance were investigated. In vitro susceptibility was assessed by the disk diffusion and broth microdilution methods. PCR assays were used to detect resistance-related genes. Coagulase and SCCmec types were identified by multiplex PCR assay.ResultsThe prevalences of constitutive MLSB, inducible MLSB, and MS phenotypes were found to be 23%, 14.2%, and 4.9%, respectively. The rates of resistance to mupirocin, fusidic acid, and tigecycline were found to be 9.3%, 4.6%, and 2.3%, respectively. The top three predominant resistance genes were mecA, tet(M), erm(C) representing 75.6, 50, and 40.7% of isolates. mupA (7%), fusB (3.5%), and fusC (1.2%) genes were also detected among tested isolates. Coagulase types were mainly type II (34.9%), followed by III (32.6%), V (20.9%), and I (11.6%).ConclusionThese findings indicated high resistance rate and low genetic variability with the prominence of coa type II, highlighting the particular importance of diagnosis of these strains to avoid treatment failure.

Antibiogram of staphylococcal isolates with special reference to inducible clindamycin resistance

Introduction and Objectives: Expression of inducible clindamycin resistance (iMLSB) by Staphylococcal isolates limits the effective use of clindamycin resulting in treatment failure. The present study was aimed to estimate the prevalence of iMLSB. Materials and Methods: Fifty Staphylococci isolated from various clinical specimens were identified by standard microbiological methods and were subjected to antibiotic susceptibility testing by Kirby-Bauer disc diffusion method and D test. Methicillin resistance was detected by cefoxitin disc diffusion method. Results: Staphylococcus aureus constituted 62% and co-agulase negative Staphylococci 38% of total Staphylococcal isolates. Methicillin resistance was noted in 27(54%) of isolates. Seventeen (34%) isolates were sensitive to both erythromycin and clindamycin. Among the resistant phenotypes, constitutive clindamycin resistance (cMLSB), Macrolide Streptogramin B resistance (MS) phenotype and iMLSB was found in 16 (32%), 10 (20%) and in 7(14%) isolates respectively. Majority of the Staphylococcal isolates showed resistance to penicillin (93.6%) followed by ciprofloxacin (79.6%) and erythromycin (66%). Linezolid resistance was observed in 8% of isolates. None of the isolates were found resistant to vancomycin. Interpretation and Conclusion: Routine testing for iMLSB for all clinical isolates of Staphylococci should be carried out to prevent failure of clindamycin therapy. Isolation of linezolid resistant Staphylococci is an alarming sign and a matter of concern. Keywords: D test, Inducible clindamycin resistance, Methicillin resistance, Staphylococci.

In Vitro Study of Constitutive and Inducible Clindamycin Resistance in Staphylococcus Aureus with Reference to Methicillin Resistant Staphylococcus Aureus: Experience From Tertiary Care Hospital in Punjab

Backround: Serious infections due to methicillin resistant Staphylococcus aureus (MRSA) have become a major clinical challenge. Globally Macrolide-lincosamide streptogramin B family of antibiotics are commonly used to treat such infections as an alternative to vancomycin. The study was to conducted to find out the presence of inducible clindamycin resistance among Staphylococcus aureus and their association with methicillin resistance. Method: The study conducted over one year (Jan 2016 - Dec 2016) in microbiology department of Guru Gobind Singh Medical College, Faridkot. Two hundred fifteen S.aureus isolates were included in the study. Methicillin resistance was detected by cefoxitin (30μg) disc diffusion method and inducible clindamycin resistance by erythromycin and clindamycin disc approximation test (D-Test). Results: Of the 215 clinical isolates of S. aureus , 140 (65.11%) were MRSA. Erythromycin and clindamycin resistance was seen in 79.06%(170/215) and 49.30% ( 106/215) respectively. Resistance to erythromycin and clindamycin were higher in MRSA than MSSA (erythromycin resistance:100%v s 22.5% and Clindamycin resistance:70.1% vs 10.6%). Both iMLSB and cMLSBphenotypes are predominant in MRSA. Conclusion: Detection of MRSA in our study shows the need to improve health care practices and to formulate new infection control policies to control MRSA infections. Inducible and constitutive resistance is comparatively higher in our study in MRSA .So It is necessary to perform D-test for detection of inducible clindamycin resistance among MRSA in routine antibiotic sensitivity testing so that therapeutic failures can be avoided.

Determine Constitutive and Inducible Clindamycin Resistance among Clinical Isolates of Staphylococcus Aureus Isolates from Tertiary Care Hospital, Bettiah, India

Determine Constitutive and Inducible Clindamycin Resistance among Clinical Isolates of Staphylococcus Aureus Isolates from Tertiary Care Hospital, Bettiah, India

Phenotypic and genotypic identification of &lt;i&gt;Staphylococcus aureus&lt;/i&gt; resistant to clindamycin in Mansoura University Children Hospital, Egypt

Background : Clindamycin has been a good alternative drug to penicillins in the treatment of infections caused by Staphylococcus aureus but resistance to this agent has led to therapeutic failure. Inducible clindamycin resistance in staphylococci carrying erm genes may not be detectable by routine disk diffusion test. The objective of this study is to phenotypically detect clindamycin resistance in clinical S. aureus isolates and determine the prevalence of ermA, ermB and ermC carriage among these isolates. Methodology : A total of 230 non-duplicate S. aureus were isolated from children admitted to Mansoura University Children Hospital during the period January 2016 and June 2017 by conventional microbiology method. Invitro antibiotic susceptibility to selected antibiotics including erythromycin was performed by the disk diffusion technique. The „D-zone‟ test was used to phenotypically detect inducible clindamycin resistance. The presence of ermA, ermB and ermC genes was confirmed by multiplex polymerase chain reaction (m-PCR) assay. Results : One hundred and seven (46.6%) isolates were phenotypically resistant to erythromycin while 109 (47.3%) were methicillin (cefoxitin) resistant S. aureus (MRSA). The macrolidelincosamin-streptograminB (MLSB) phenotypes among the erythromycin resistant isolates were 47 (44%) inducible MLSB and 46 (43%) constitutive MLSB, while 14 (13.0%) were MS phenotype. Although, the MLSB phenotype was more predominant in MRSA (n=60, 56.1%) than MSSA (n=33, 30.7%) while the MS phenotype was more predominant in MSSA (n=9, 8.4%) than MRSA (n=5, 4.6%) isolates, the difference was not statistically significant (p=0.0777). The ermA (29.0%, n=31) and ermC (18.7%, n=20) were the most prevalent genes carried by the isolates while ermB was carried by a few (4.7%, n=5). Forty six (43%) isolates did not carry any detectable erm gene. Conclusion : In this study, both inducible and constitutive clindamycin resistance phenotypes were common among S. aureus isolates. Although the genetic basis for this may be attributed to carriage of ermA, ermB and ermC genes, a number of the resistant isolates did not carry any of these genes. Keywords : phenotypic, genotypic, macrolide-lincosamide-streptogramin B, S. aureus, children,

Vancomycin Resistant Staphylococcus aureus Reported from Tertiary Care Hospital in Nepal

Objectives: The study was conducted to assess the rate of Methicillin-resistant Staphylococcus aureus (MRSA) among patients and healthcare personnel at Manmohan Memorial College and Teaching Hospital, Kathmandu, Nepal and to evaluate the minimum inhibitory concentration of Vancomycin to MRSA isolates.Methods: A total of 1433 different clinical specimens from patients and 33 nasal swabs from healthcare personnel were subjected to bacteriological investigation following standard protocol. S. aureus were isolated and identified by using standard Microbiological tools. Those isolates were subjected to Antimicrobial susceptibility testing using modified Kirby-Bauer’s disc diffusion method following CLSI guidelines.Results: The rate of S. aureus carriage was found to be 65 (18.9%) in the samples from clinical patients and 24 (72.7%) in the samples from healthcare personnel. The rate of MRSA was found to be 57(85.1%) in patients and 24 (100%) in healthcare personnel. The high distribution of MRSA was found in female of age group 21-30 years (patients: 10.4%; healthcare personnel: 70.8%). Amikacin was found to be most effective antimicrobial. All S. aureus isolates were found to be multidrug resistant (100%). On performing D-test, 10 (17.5%) and 22 (38.6%) of MRSA from clinical specimens showed inducible and constitutive Clindamycin resistance respectively. Whereas, 11 (45.8%) and 4 (16.7%) of MRSA from nasal swabs were found to be inducible and constitutive Clindamycin resistance respectively. Upon performing minimum inhibitory concentration (MIC) test for clinical isolates, 3.5% (2) of MRSA were found to be Vancomycin resistant (VRSA), 54.4% (31) were Vancomycin intermediate (VISA) and 42.1% (24) were found to be Vancomycin sensitive (VSSA). All of the nasal swab MRSA isolates were found sensitive to Vancomycin. Congo red agar method was done for biofilm production. For clinical isolates, 32 (47.8%) were found to be strong, 6 (8.9%) moderate and 29 (43.3%) were non biofilm producer. For nasal swab isolates, 66.7% (16) and 33.3% (8) were found as strong and non-biofilm producer respectively.Conclusion: This study reported the case of VRSA which hasn’t been reported in Nepal. Though present study showed that Vancomycin remains the main choice of treatment of MRSA infection. Therefore, to preserve its value, use of vancomycin should be limited only to those cases where there are clearly needed.

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

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. 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 (MLSB) 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). 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, iMLSB was identified in five isolates (three of which were also MRSA). The majority of the erythromycin-resistant isolates harbored the msrA gene (four iMLSB) with the remaining iMLSB isolate harboring the ermC gene. The presence of MRSA isolates which are also iMLSB in healthy individuals suggests that nasal carriage may play a role as a potential reservoir for the transmission of these pathogens.