scholarly journals Peculiarities of antibiotic resistance of Staphylococcus aureus strains isolated from nosocomial infections

2020 ◽  
Vol 101 (3) ◽  
pp. 325-329
Author(s):  
S A Atakishizade

Aim. To study of the antibiotic resistance of S. aureus strains isolated from nosocomial infections (pneumonia, surgical site infections and sepsis) in a multidisciplinary surgical clinic. Methods. Microbiological testing of sputum in 41 patients with pneumonia, of samples (wound, abscess, drainage) obtained from 40 patients with surgical site infections (SSI) and of blood from 46 patients with signs of sepsis was performed. The obtaining cultures were identified by conventional methods (including morphological, cultural, biochemical features, etc.). Disc diffusion method was used to detect methicillin-resistant S. aureus (MRSA) strains. Inducible clindamycin resistance (ICR) of S. aureus strains was determined by double disk approximation test (D-test). Results. Methicillin-resistant S. aureus was found in 14.3% (2 of 14) of the patients with surgical site infections, in the sputum 27.3% (3 of 11) of the patients with pneumonia, and in the blood 50.0% (7 of 14) of the patients with sepsis (p 0.05). The rate of inducible clindamycin resistance of isolated S. aureus strains in patients with surgical site infections (2 of 14 cases, 14.3%) and with pneumonia (2 of 11 cases, 18.2%) did not statistically significant difference with the rate of methicillin resistance (p 0.05). However the rate was significantly lower septic infections 7.1% and 50.0% respectively (p=0.0328). Conclusion. Among S. aureus strains isolated from nosocomial infections, the rate of methicillin-resistant S. aureus had not depended on the type of nosocomial infection; the rate of inducible clindamycin resistance in septic infections was lower than resistance to methicillin.

Author(s):  
Somaye Delfani ◽  
Faranak Rezaei ◽  
Setareh Soroush ◽  
Pegah Shakib

Background: Methicillin-resistant coagulase-negative staphylococci is responsible for hospital and community-acquired infections. Objective: This study aimed to investigate the antibiotic-resistance patterns, antibiotic-resistance genes, namely, ermA, ermB, ermC, blaZ, msrA, tetK, tetM, mup, and vanA, biofilm formation, and prevalence of different SCCmec types among the Staphylococcus cohniistrains isolated from clinical samples in Tehran, Iran. Methods: In this study,S. cohniiisolates were screened from the clinical samples from March 2012 to February 2013 in Tehran, Iran.Antimicrobial susceptibility test and inducible clindamycin resistance were evaluated by disc diffusion method, andresistance genes were examined using Polymerase Chain Reaction (PCR) assays. Then, biofilm formation assay was analyzed by Microtiter-plate test to detect the icaA and icaDgenes. The SCCmec and the Arginine Catabolite Mobile Element (ACME) typing were performed using the PCRmethod. Results: FromtwentyS. cohnii, all isolates were resistant to cefoxitin. 95% of the S. cohnii was defined as multidrug resistance (MDR)strains. The ermB, ermC, and vanA genes were not detected in any isolates; however, the blaZ gene had the highest frequency.95% of the S. cohnii isolates produced biofilm. Also, 4 SCCmec types, including V, IV, III+ (C2), VIII+ (AB1), were identified. Therefore, the majority of SCCmec were untypable. Based on the ACME typing, arcA and opp3 genes were positive in 13 (65%) and 1 (5%) isolates, respectively. Conclusion: Due to the high antimicrobial resistance and the spread of untypableSCCmecamong the isolates studied, the control and treatment of methicillin-resistantS. cohnii in hospitals and public health centers is a significant concern.


2020 ◽  
Vol 73 (12) ◽  
pp. 2563-2567
Author(s):  
Aidyn G. Salmanov ◽  
Taras P. Bondar ◽  
Yaroslav V. Shkorbotun ◽  
Evelina A. Chumak ◽  
Volodymyr O. Shkorbotun ◽  
...  

The aim: To obtain the first estimates of the current prevalence of nasal carriage of methicillin-resistant Staphylococcus aureus (MRSA) among healthcare workers (HCWs) in the departments of Otorinolaryngology and Dentistry and to determine of genes virulence factors (Panton Valentine Leukocidine (PVL) genes). Materials and methods: We performed a multicenter cross-sectional study. The susceptibility to antibiotics was determined by disk diffusion method according to the European Committee on Antimicrobial Susceptibility Testing. The virulence factor encoding genes, mecA, lukS-lukF, were detected by Polymerase Chain Reaction (PCR). Results: Incidence rate of S. aureus nasal carriage among HCWs was 36.2%, whereas MRSA carriage was 17%. Prevalence of MRSA carriage rate was 34.9% in Otorhinolaryngology departments and 9.7% in Dentistry. PCR testing confirmed that all MRSA strains were mecA gene-positive. The virulence factor encoding genes were detected in 82.3% of the S. aureus isolates from HCWs. Among S.aureus, the lukS-lukF genes were detected in over 59% of the strains. The lukS-lukF genes were detected in 55.5% of MRSA and in 58.9% of MSSA strains. LukS-lukF genes were most commonly co-present in MRSA strains. No significant difference was detected between the occurrences of lukS-lukF genes (P > 0.05). Conclusions: Personnell in otorhinolaryngology and dentistry departments have a high rate of nasal colonization of MRSA. This carrier state may be an important risk factor for transmission MRSA from physicians and nurses to patients and vice-versa. Screening for MRSA nasal carriage of HCWs is a key element in enabling infection control measures and early therapeutic decisions.


Author(s):  
Safana A. A. Alhady ◽  
Musa Abdalla Ali

Background : S. aureus is frequently associated with skin infections, pneumonia, surgery wounds, bacteraemia, osteomyelitis and endocarditis, being considered one of the most important pathogens of the human being, both at the community level and at nosocomial infections, and may become serious if caused by antimicrobial resistant strains, especially methicillin-resistant S. aureus (MRSA) strains, which are resistant to most of the antimicrobial agents, methicillin-sensitive S.aureus (MSSA) and isolates with reduced susceptibility and resistance to vancomycin, which is the last drug for the treatment of MRSA infections. So, this study aimed to detect the existence of inducible resistance of S. aureus to Clindamycin in Khartoum-Sudan among patients attended to Suba University Hospital. Methods : The study was performed as cross-sectional one, 53 clinical isolates of S. aureus obtained from (34 females and 19 males) with different clinical condition among patients attended to Suba University Hospital in Khartoum-Sudan from April to August 2017. To detect inducible clindamycin resistant by using D test. In addition to that MRSA / MSSA all the isolates screened for methicillin resistant by using 1 µg oxacillin then examined for inducible clindamycin resistant by D test. In addition to that examine for antimicrobial susceptibility profile which include vancomycin, gentamycin, tetracycline and co-trimoxazole. The data were analyzed using Statistical Package for Social Science, version 22, P. value <0.05 was considered statistically significant Results : out of 53 isolates, 36 S. aureus isolated resistant to Clindamycin, 26 (72.2%) were MRSA and 10 (27.8%) were MSSA by means of D test, while 17 (32.1%) of isolates were sensitive 9 (53%) MRSA and 8 (47 %) MSSA. Comparing Induced clindamycin resistance showed equally distribution among MSSA and MRSA isolates, giving no significant difference as P- value 0.167. Conclusion : This study showed that D.test to detect inducible clundamycin resistance in staphylococcus aureus.


2015 ◽  
Vol 6 (6) ◽  
pp. 48-52
Author(s):  
Fatima Khan ◽  
Sana Ali ◽  
Asfia Sultan ◽  
Meher Rizvi ◽  
Abida Khatoon ◽  
...  

Introduction: Erythromycin resistant Staphylococcus isolates with inducible resistance appear sensitive to clindamycin in in?vitro sensitivity testing. If clindamycin is used for treatment of such isolates, selection for constitutive mutants may lead to clinical failure. Current study was conducted to detect the presence of inducible clindamycin resistance in erythromycin resistant Staphylococcus isolates by disk diffusion method (D test). To correlate clindamycin resistance phenotypes with minimum inhibitory concentrations (MICs) of clindamycin, erythromycin, oxacillin and vancomycin among the isolates. To correlate various resistance phenotypes with methicillin resistance. Material and Methods: 150 non duplicate isolates of Staphylococcus species were identified and antibiotic susceptibility testing was done using Kirby Bauer’s disc diffusion method. MICs were determined using E?test for oxacillin, vancomycin, clindamycin and erythromycin using E?test strips (Himedia) Results: Among 150 staphylococcus clinical isolates, 96 were of S. aureus and 54 were coagulase negative Staphylococci (CONS). About 81.2% of the S.aureus isolates and 72.2% of the CONS were found to be methicillin resistant. Inducible clindamycin resistance was found in 39.3% of the isolates, constitutive resistance phenotype in 48% while 12.7% demonstrated MS phenotype. 18% and 11.3% of all the isolates had MICs for clindamycin between 0.01?0.06 μg/ml and 0.06?0.1 respectively. 12.5% had MIC ranging from 4?8 μg/ml while 58% had MIC > 8 μg/ml. Constitutive resistant phenotype (cMLS) was the predominant phenotype in methicillin resistant isolates. MS phenotype was the predominant among MSSA (methicillin sensitive S. aureus) while MSCNS (methicillin sensitive CONS) cMLS (46.7%) predominated. MIC of all erythromycin resistant isolates were ≥ 240 μg/ml. Nearly 16.7% of the cMLS and 57.9% of MS isolates were found to be oxacillin sensitive and 83% of iMLS and 83.3% of MS phenotype isolates were oxacillin resistant on MIC testing. 47.2% of cMLS and 73.6% of MS isolates had MIC ≤ 2 μg/ml for vancomycin and 52.7% of cMLS and 26.3% of MS isolates had MICs in intermediate range for vancomycin. Conclusions: D?testing might help clinicians to decide whether to use clindamycin in Staphylococcal infections when erythromycin resistance is present. Determination of MICs help to identify exact sensitivity profile of isolates in cases where clinical failure occurs due to misleading disk diffusion tests.DOI: http://dx.doi.org/10.3126/ajms.v6i6.11811 Asian Journal of Medical Sciences Vol.6(6) 2015 48-52


2019 ◽  
Vol 7 (4) ◽  
pp. 121-125
Author(s):  
Fatemeh Mahdavi ◽  
Fatemeh Zaboli ◽  
Rahem Khoshbakht

Background: Methicillin-resistant Staphylococcus aureus (MRSA) strains are one of the most important multidrug resistant microorganisms that threaten human health. Objective: The present study was conducted to evaluate genotypic and phenotypic characteristics of erythromycin resistance among MRSA isolates recovered from raw milk in Iran. Materials and Methods: A total of 50 MRSA isolates were recovered from raw milk. Tests for erythromycin and clindamycin susceptibility and inducible clindamycin resistance were done. In addition, the presence of the methicillin resistance determinant (mecA), erythromycin resistance genes (ermA, ermB, ermC and msrA) and an important virulence gene (Panton– Valentine leukocidin) were investigated using polymerase chain reaction (PCR) method. Results: Forty-eight percent (24/50) and 46% (23/50) of the isolates were resistant to erythromycin and clindamycin, respectively. Seven (14%) isolates showed inducible clindamycin resistance phenotype. The mecA gene was detected in 88% (44/50) of MRSA isolates. The incidence of the ermA, ermB, ermC and msrA genes was 14%, 64%, 12%, and 26%, respectively and the PVL gene was present in 18% (9/50) of MRSA isolates. Conclusion: According to the results of the study, the incidence of erythromycin resistance genes and inducible clindamycin-resistant MRSA strains was high in raw milk samples in Iran.


Author(s):  
Fahimeh Nourbakhsh ◽  
Vajiheh Nourbakhsh ◽  
Samaneh Borooni ◽  
Elaheh Tajbakhsh ◽  
Dana Daneshmand

Background and Aims: Based on the results, Staphylococcus aureus is one of the serious infectious agents found in community and hospitals with remarkable potential for high morbidity and mortality around the globe. The present study was carried out for molecular investigation of methicillinresistant Staphylococcus aureus strains and Staphylococcal Chromosomal Cassette mec (SCCmec) phenotypes isolated from the intensive care unit in Hazrat Fatemeh Zahra hospital of Isfahan. Materials and Methods: A total of 76 clinical wound samples were collected from Hazrat Fatemeh Zahra Hospital in Isfahan and evaluated by polymerase chain reaction (PCR) methods. The Methicillin resistance Staphylococcus aureus (MRSA) screening was performed by genotypic and phenotypic methods; also antibiotic resistance pattern was determined by using the disk diffusion method and related genes by PCR. Results: Totally, 53 (69.7%) out of 76 clinical samples were positive for MRSA. Of the 76 MRSA strains, 39 (63.51%) were PVL positive (51.3%). The most commonly infected samples were collected from wounds (40.8%). The most commonly detected antibiotic resistance genes were mecA (89.61%), tetK (88.23%), tetM (49.15%) and msrA (46.93%). Resultantly, it was shown that MRSA has the highest level of resistance against methicillin (98%), penicillin (97.24%), tetracycline (89.64%). It was also revealed that the most commonly detected SCCmec types in the MRSA strains are types II (14.53%) and III (16.82%). Conclusions: In summary, this paper argues that the orderly surveillance of hospital-associated infections and initial management and supervision of the antibiotic resistance patterns are required to control the prevalence of MRSA.


Author(s):  
Iulia Maria BUCUR ◽  
Viorel HERMAN ◽  
Corina PASCU ◽  
Ionita IANCU ◽  
Janos DEGI ◽  
...  

Keywords: chromogen, methicillin, MRSA, resistanceIntroduction: Currently, both in staphylococci isolated from animals with different diseases, as well as in humans, the MRSA strains (Methicillin Resistant S. aureus) are monitored, as the methicillin resistance is associated with the resistance to other antibiotic groups.Methicillin resistance is encoded by mec staphylococcal chromosomal cassettes (SCCmec), which are islands of resistance. These strains can be identified by molecular biology tests and tests that reveal several phenotypic characteristics.The research was made in order to characterize and identify phenotypically the MRSA staphylococci strains isolated from animals.Materials and Methods: Researches were made on 240 coagulase positive and coagulase negative strains of staphylococci. Mannitol fermentation was tested on Champan medium, free coagulase was revealed on Baird-Parker medium and to identify S. aureus subsp. aureus was used the chromogenic medium Chromatic Staph.Methicillin-resistant strains were detected by disc diffusion method, using biodiscs with methicillin, oxacillin and cefoxitin. Also, to identify the MRSA strains, was used the chromogenic medium Chromatic MRSA.Results: The isolates were positive to mannitol and produced complete haemolysis or were unhaemolytic. A total of 44 strains produced free coagulase on Baird-Parker medium, considered coagulase positive strains, while 196 were coagulase negative strains.The isolates conducted differently to methicillin: 22,08% of strains were resistant, 51,25% of strains were susceptible and 26,66% had intermediate resistance, while the resistant strains to oxacillin were 42,91%.The increased frequency of methicillin-resistant strains of staphylococci and, particularly, MRSA strains, determined using the cefoxitin disk diffusion test, which is more reliable than methicillin and oxacillin.On the MRSA chromogenic medium, the methicillin-resistant strains of staphylococci formed colonies with pigment from mauve to orange mauve.Conclusion: The obtained results by disk diffusion test on resistance patterns to 3 beta-lactams, resistant to penicillinase, indicated a different frequency of the resistant strains to these antibiotics.Cefoxitin disk diffusion test revealed a frequency of 2,51% of resistant strains, that can be considered MRSA strains.


2018 ◽  
Vol 2 (1) ◽  

Aim: In today’s scenario, Nosocomial infection is a foremost problem in world. Methicillin resistant staphylococcus aureus (MRSA) strains are not only resistant to several antibiotics but also, show a particular ability to spread in hospitals of many countries. The main objective of the present study is to determine the prevalence of MRSA in surgical wound infections and also to define the antimicrobial susceptibility patterns of the strains isolated. Materials and Methods: A total of 133 culture positive Staph.aureus were taken from surgical site wound infections for the study during the period from March 2016 to February 2017. Routine Antibiotic Susceptibility testing was performed and interpreted as per latest CLSI guidelines. Methicillin resistance was detected using cefoxitin disc diffusion method. Results: In total of 133 samples, 81 (60.9%) were found to be MRSA. However, no strain was resistant to Vancomycin, Linezolid or Teichoplanin. Conclusion: Vigorous antimicrobial stewardship and strengthened infection control practices are mandatory to prevent spread and reduce emergence of resistance. Customary surveillance of hospital-associated infection and monitoring of antibiotic sensitivity pattern is required to reduce MRSA prevalence.


2019 ◽  
Vol 2019 ◽  
pp. 1-9 ◽  
Author(s):  
Mohammedaman Mama ◽  
Addis Aklilu ◽  
Kassahun Misgna ◽  
Molla Tadesse ◽  
Eyerusalem Alemayehu

Background. Wound infection is one of the most common hospital-acquired infections. Different bacteria cause infection, of whichStaphylococcus aureusis one of the known bacteria in causing infection with increased drug-resistant isolates.Objective. To assess the prevalence and antimicrobial susceptibility pattern of methicillin and inducible clindamycin-resistantStaphylococcus aureusamong patients with wound infections attending Arba Minch Hospital.Methods. A facility-based cross-sectional study was conducted from April to June 2017. A pretested questionnaire was used to collect demographic data and clinical characteristics. Wound swabs were cultured and identified by standard techniques. Antibiotic susceptibility tests were performed by the Kirby–Bauer disc diffusion method. Methicillin resistance was detected using the cefoxitin (30 μg) antibiotic disc while inducible clindamycin resistance was detected by the D-zone test. The data were analyzed using Statistical Package for Social Science, version 20.pvalue <0.05 was considered statistically significant.Results. A total of 161 patients were enrolled and a majority of them were female (90, 50.9%). Among the collected samples, 79 (49.7%) were positive forS. aureus; of this, methicillin resistance accounted for 65 (82.3%). Out of 22 (27.8%) erythromycin-resistant isolates, 19 (24.1%) showed inducible clindamycin resistance. Methicillin-resistantS. aureusshowed higher resistance against tetracycline (72.3%) followed by cotrimoxazole (43.1%) and 100% sensitivity to vancomycin. The overall prevalence of inducible clindamycin resistance among methicillin-resistant isolates was 16 (24.6%).Conclusion. The increasing prevalence of methicillin-resistantS. aureusand the coresistance against other therapeutic options like clindamycin is becoming an obstacle in the treatment of infections which need attention from concerned bodies.


2021 ◽  
Vol 49 (1) ◽  
Author(s):  
Devi Thapa ◽  
Susil Pyakurel ◽  
Sabita Thapa ◽  
Suresh Lamsal ◽  
Mahesh Chaudhari ◽  
...  

Abstract Background Staphylococcus aureus is a global public health issue in both community and hospital settings. Management of methicillin-resistant S. aureus (MRSA) infections are tough owing to its resistance to many antibiotics. Macrolide-lincosamide-streptogramin B (MLSB) antibiotics are commonly used for the management of MRSA. This study was aimed to determine the occurrence of inducible clindamycin- and methicillin-resistant S. aureus at a tertiary care hospital in Kathmandu, Nepal. Methods A total of 1027 clinical samples were processed following standard laboratory procedures and antibiotic susceptibility testing of S. aureus was performed by disc diffusion method. MRSA isolates were detected phenotypically using cefoxitin disc, and inducible clindamycin resistance was detected phenotypically using the D-zone test. Results Of 1027 samples, 321 (31.2%) were culture positive, of which 38 (11.8%) were S. aureus. All S. aureus isolates were susceptible to vancomycin, and 25 (67%) of S. aureus isolates were multidrug-resistant. Similarly, 15 (39.5%) of S. aureus were MRSA and 14 (36.5%) were inducible clindamycin-resistant phenotypes. Conclusion Inducible clindamycin and methicillin resistance were common in S. aureus. This emphasizes that the methicillin resistance test and the D-zone test should be incorporated into the routine antibiotic susceptibility testing in hospital settings.


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