Methicillin-sensitive Coagulase-negative Staphylococci Research Articles

Microorganisms isolated from thermoplastic masks and storage racks in head and neck cancer patients with radiation dermatitis.

Healthcare-associated infections (HAIs) remain a critical public health issue, as they contribute to prolonged treatment duration, increased healthcare costs, and heightened risks of morbidity and mortality. In head and neck cancer patients undergoing radiotherapy, thermoplastic masks (TMs), which come into direct contact with the skin, represent a potential vector for infection. Additionally, the storage racks where these masks are kept may also facilitate microorganism transmission. Our study aimed to isolate and identify microorganisms from infective skin lesions secondary to radiation dermatitis in head and neck cancer patients, as well as from the TMs and storage racks, and to evaluate the antibiotic resistance profiles of the isolated microorganisms. The study included 71 locally advanced head and neck cancer patients who underwent radiotherapy between August 2022 and November 2023. Patients were monitored daily, and their skin evaluations were made according to Common Terminology Criteria for Adverse Events (CTCAE) version 4.0. Grade 2 and 3 radiodermatitis was observed in 29 of these 71 patients. Samples were collected using sterile swabs from the skin lesions on the head and neck area, the inner surfaces of the TM, and the storage rack from 29 patients. Samples were inoculated into enrichment and selective media. After the growing microorganisms were identified, antimicrobial susceptibility was evaluated using conventional methods and automated systems according to the European Committee on Antimicrobial Susceptibility Testing (EUCAST) criteria. At least one type of microorganism was isolated from the skin samples of infected patients, and double growth was detected in two patients. Among the samples, 2 were methicillin-resistant coagulase-negative Staphylococcus (MRCNS), 1 was methicillin-resistant Staphylococcus aureus (MRSA), 1 was Candida albicans (C. albicans), 15 were methicillin-sensitive coagulase-negative Staphylococcus (MSCNS), 1 was methicillin-sensitive Staphylococcus aureus (MSSA), 1 was Bacillus subspecies (Bacillus spp.) and 3 were Corynebacterium diphtheriae (C. diphtheriae). Coagulase-negative Staphylococcus strains were isolated from the skin of 14 of 19 patients with grade 2 radiation dermatitis, whereas CNS strains were isolated from only 2 of 10 patients with grade 3 radiation dermatitis. Among the gram-negative bacteria, 3 Pseudomonas aeruginosa (P. aeruginosa), 2 Enterobacter cloacae (E. cloacae), 1 Klebsiella pneumoniae (K. pneumoniae) and 1 Moraxella catarrhalis (M. catarrhalis) strain were isolated. Sixteen (55.1%) of the TMs used in 29 patients and 20 (68.9%) of the storage racks harbored microorganisms, including HAI agents and flora bacteria. Bacteria colonize TMs and storage racks where they are risk factors for secondary skin infections in radiation dermatitis lesions that develop on the skin of head and neck cancer patients. Decontamination procedures should be meticulously applied to surfaces such as TMs and their storage racks during the course of radiotherapy.

Evaluation of Blood Culture Results in Patients with Malignancy in Erzurum Province, Turkey.

Bloodstream infections are a serious public health problem that requires follow-up with blood culture; this negatively affects the course of the disease and patient healthcare costs in patients with malignancy. This study aimed to determine the growth frequency of pathogens and their antibiotic resistance profiles in the blood cultures of patients with hematological and oncogenic malignancies. The results of 7451 blood cultures, obtained from 2926 patients between January 2017 and January 2022, were evaluated retrospectively. Of these cultures, 3969 were obtained from patients with malignancy (diagnostic codes C00-D48 in ICD-10) and 3482 from patients without malignancy. The hospital information management system modules were used to acquire patient data and blood culture results. Various microorganisms grew in 10.1% of blood cultures. Of these organisms, 64.1% were isolated from cases of malignancy. Of the pathogens, 49.2% were gram-negative bacteria, 47.7% were gram-positive bacteria, and 3.1% were fungi. The most frequently isolated bacteria were methicillin-resistant coagulase-negative staphylococci (3.2%), Escherichia coli (2.3%), Klebsiella pneumoniae (1.0%), methicillin-sensitive coagulase-negative staphylococci (0.7%), and Staphylococcus aureus (0.6%). Pathogen positivity was highest in the patient cultures with urinary system cancer (23.9%), thyroid and other endocrine gland cancers (20.6%), female and male genital organ cancers (18.2%/16.9%), and digestive organ cancer (14.2%). Gram-negative bacteria to ampicillin, piperacillin, and sulfamethoxazole-trimethoprim and Gram-positive bacteria to penicillin, erythromycin, and sulfamethoxazole-trimethoprim were highly resistant. Combined resistance to imipenem and meropenem was observed in 25 Gram-negative bacteria. Twelve (48%) of the carbapenem-resistant bacteria were isolated from patients with lymphoid, hematopoietic, and related tissue malignant neoplasia. This study reported microorganisms and their antimicrobial resistance in the blood cultures of malignant patients, a special patient group. It pointed out that the antibiotic resistance of Staphylococcus, Klebsiella pneumoniae, and E. coli is high enough to cause problems in the treatment of patients with malignancy.

Identification and characterization of SCCmec typing with psm-mec positivity in staphylococci from patients with coagulase-negative staphylococci peritoneal dialysis-related peritonitis

BackgroundPeritonitis is the most important complication of peritoneal dialysis (PD) and coagulase-negative staphylococci (CNS) are a frequent cause of dialysis-related infections. The association between SCCmec typing with psm-mec positivity in staphylococci and PD-related infections has not been identified. We aim to investigate the molecular epidemiology of CNS isolated from PD-peritonitis in a single Chinese center, focusing on the genetic determinants conferring methicillin resistance.MethodsWe collected 10 genetically unrelated CNS isolates from 10 patients with CNS PD-related peritonitis. The patients were divided into two groups based on the results of MIC to oxacillin: the methicillin-resistant CNS (MRCNS) and methicillin-sensitive CNS (MSCNS) groups. The biofilm formation group (BFG) and the non-biofilm formation group (NBFG) were used as the control groups. Phenotypic and molecular methods were used to analyze SCCmec types I, II and III, associated genes and biofilm formation and the existence of psm-mec. The demographic data and clinical indicators were collected.ResultsTen CNS PD-related peritonitis patients were enrolled for this study. There were 6 MRCNS and 4 MRCNS isolates. SCCmec types were fully determined in 10 isolates. Seven staphylococci (70%) carried SCCmec, of which 4 isolates carried single SCCmec type I (40%) and 3 isolates had multiple SCCmec elements (I + III). Of the 6 MRCNS isolates, 3 carried SCCmec type I (50%) and 2 isolates carried SCCmec type I + III (33.3%). A high diversity of ccr types, mec complexes and ccr-mec complex combinations was identified among the 10 CNS isolates. The psm-mec gene was detected in 2/10 (20%) CNS isolates. There was no mutation in the psm-mec gene.ConclusionsThe majority of isolates were hospital-associated isolates. Furthermore, 2 psm-mec positive isolates were MRCNS in the NBFG. The PD patients frequent exposure to hospital would be the main risk factor. The presence of the psm-mec signal in the spectra of the MRCNS tested here demonstrates the presence of certain SCCmec cassettes that convey methicillin resistance.

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.

Speciation and Antibiotic Susceptibility Pattern of Coagulase Negative Staphylococci in a Tertiary Care Hospital of Manipur, India

Introduction: Coagulase Negative Staphylococci (CoNS) are common opportunistic pathogens. They are increasingly being recognised as nosocomial pathogens and are associated with multiple antimicrobial resistance mechanisms particularly methicillin resistance. Therefore, rapid and reliable identification upto the species level is necessary to predict the potential pathogenicity or antibiotic susceptibility of each clinical isolate. Aim: Isolation and speciation of CoNS from various clinical samples, and to determine their antibiotic susceptibility pattern. Materials and Methods: This study was a hospital-based crosssectional study carried out in the Department of Microbiology, Jawaharlal Nehru Institute of Medical Sciences (JNIMS), Imphal, Manipur, India, during the period from September 2017- August 2019. CoNS isolates were identified using conventional microbiological procedures and speciation was done following the scheme of Kloos and Schleifer. Antibiotic susceptibility was determined by using the Kirby Bauer’s disk diffusion method. Detection of methicillin resistance among CoNS was performed using cefoxitin disk (30 µg) diffusion method. Data analysis was done using descriptive statistics. Results: CoNS isolates were identified from different clinical specimens, which included 88 (65.2%) from urine, 37 (27.5%) from blood, 3 (2.2%) from pus, 2 (1.5%) from catheter tip, 2 (1.5%) from wound swab, 1 (0.7%) each from aural swab, sputum and ascitic fluid. Predominant isolates were Staphylococcus epidermidis (40.7%) followed by Staphylococcus haemolyticus (19.3%), Staphylococcus hominis (11.9%), Staphylococcus xylosus (7.4%), Staphylococcus saprophyticus (6.0%), Staphylococcus schleiferi (5.2%), Staphylococcus simulans (4.4%), Staphylococcus warneri (3.0%), Staphylococcus lugdunensis (0.7%), Staphylococcus capitis (0.7%) and Staphylococcus cohnii (0.7%). Most isolates were resistant to penicillin (84.5%) and erythromycin (59.3%), and least to tigecycline (2.2%). No resistance to vancomycin and linezolid was seen. Methicillin sensitive CoNS (MSCoNS) was detected in 79 (58.5%) isolates and methicillin resistant CoNS (MRCoNS) in 56 (41.5%) isolates. Conclusion: This study demonstrated the occurrence of various species of CoNS in our healthcare set up with varying antimicrobial susceptibility pattern. Therefore, there is a need for accurate identification to species level by simple, inexpensive methodology and their antibiogram.

Bacterial strains colonizing the sensor electrodes of a continuous glucose monitoring system in children with diabetes

IntroductionThe higher frequency of infections in diabetic patients is caused by a hyperglycemic environment, which promotes immune dysfunction. People with diabetes are more prone to skin infections.A continuous glucose monitoring (CGM) system provides information on changes in blood glucose (BG) levels throughout the day. Its use facilitates optimal therapeutic decisions for a diabetic patient. One of the factors limiting the use of CGM is inflammation at the insertion site.Aim of the studyThe aim of the study was the microbiological identification of the bacterial strains which are found on CGM sensor electrodes.Material and methodsWe performed microbiological tests on patients′ CGM Enlite Medtronic electrodes, which were removed after 6 days of usage according to the manufacturer′s instructions. 31 sensors were examined from 31 children (14 girls) aged from 0.5 to 14.6 years. The microbiological analysis was routinely performed at the Department of Children’s Diabetology Medical University of Silesia in Katowice, Poland.Results12 (39%) of the electrodes were colonized. In 11 (92%) cases the electrodes were colonized by one bacteria strain. 7 times methicillin-sensitive coagulase negative staphylococcus (MSCNS) was detected. We also found one case of Klebsiella pneumoniae, Ochrobactrum tritici, Bacillus sonorensis and methicillin-resistant coagulase-negative Staphylococci (MRCNS) colonization. One electrode was colonized by the mixed flora Enterococcus faecalis, methicillin-susceptible coagulase-negative Staphylococci (MSCNS), Pseudomonas stutzeri, methicillin-susceptible Staphylococcus aureus (MSSA). The median HbA1c in the group with colonization of electrodes was 6, 85% (6, 3–7, 6%) versus 6, 3% (5, 8–7, 5%) in the group without colonization. The median BMI in the group with colonization of the electrodes was 17.10 kg/m2 (16.28–18.62 kg/m2) versus 15.98 kg/m2 (15.14–17.96 kg/m2) in the group without colonization. Statistically, significantly more frequently electrodes are colonized in older children (median age in the group with colonization of electrodes 11.43 years (6.52–12.27 years), without colonization 8.42 years. (3.098–9.375 years); (p = 0.033).ConclusionsIt seems that older children are more likely to have their sensor electrode colonized by bacterial strains.

Nasal conveyance of Methicillin-resistant Staphylococcus aureus (MRSA) strains among dental professionals with varying levels of clinical exposure: A comparative study

ObjectiveAny control program for MRSA requires identifying the whole hospital reservoir. The likelihood of conveyance of MRSA may be higher in dental settings. Hence, the aim was to compare the nasal conveyance MRSA among dental professionals with varying levels of clinical exposure in a tertiary dental hospital in South India. MethodsA total of 81 volunteers were stratified based on the number of years of clinical exposure. The nasal swabs were subjected to catalase and coagulase tests as well as antibiotic susceptibility test. Chi- Square test was done to compare the different types of organisms isolated from dental professionals with varied levels of clinical exposure. ResultsOut of the total 81 isolates, 62.96% of the isolates were MSCONS (Methicillin sensitive coagulase negative staphylococcus), 20.98% of them were MRCONS (Methicillin resistant coagulase negative staphylococcus), 9.87% were MSSA (Methicillin sensitive staphylococcus aureus) and 3.7% were MRSA positive and 2.46% were other gram negative organisms. ConclusionsMRCONS, MSSA and MRSA were shown to increase with an increase in the clinical exposure years.

Inducible clindamycin resistance among Staphylococcal clinical isolates from Tripoli Central Hospital, Libya

Abstract Background: The resistance to antimicrobial agents among Staphylococci is an increasing problem. This has led to a renewed interest in the usage of macrolide-lincosamide-streptogramin B (MLSB) antibiotics to treat staphylococcal infections. Clinical failure has been reported due to multiple mechanisms that confer resistance to clindamycin antibiotics. The present study was to investigate the inducible clindamycin resistance among isolates of methicillin resistant Staphylococci by the D-test method. MATERIALS & METHODS: This study was conducted on 218 staphylococcal isolates obtained from different clinical specimens of outpatients and inpatients admitted to Tripoli Central Hospital (TCH), Libya. Methicillin resistance was detected by oxacillin, cefoxitin disc diffusion test (Kirby Bauer method) and confirmed by other biochemical tests. Detection of inducible clindamycin resistance was performed by D-test using erythromycin and clindamycin. Results: Eighty-six out of 218 staphylococcal isolates were resistant to erythromycin,26 (11.9%) isolates were D-test positive indicating inducible (iMLSB) phenotype, 24 (11%) isolates exhibited constitutive (cMLSB) phenotype, while 36 (16.5%) showed true sensitivity to clindamycin indicating (MS) phenotype. The distribution of isolates showing iMLSB phenotype was 12 (19.4%) for methicillin-resistant Staphylococcus aureus (MRSA), 8 (17.0%) for methicillin-resistant coagulase-negative Staphylococci (MRCNS), 6 (6.4%) for methicillin-sensitive Staphylococcus aureus (MSSA) and 0 (0%) for methicillin-sensitive coagulase-negative Staphylococci (MSCNS). Conclusion: Higher prevalence of iMLSB phenotype was mainly associated with methicillin-resistant than methicillin-sensitive isolates. We recommend that D-test should be performed to facilitate the appropriate treatment of patients infected with Staphylococci.

Detection of Antiseptic Resistance Genes among Staphylococcus aureus Colonising Nurses and Coagulase-Negative Staphylococci Isolated from Clinical Specimens at Teaching Hospitals in Southwest of Iran

Background: The wide application of antibiotics and antiseptics for patient therapy and medical equipment and surfaces disinfection has resulted in the emergence of resistant microorganisms. Staphylococcus aureus and coagulase-negative Staphylococci (CoNS) are found as a part of the normal resident flora in human so that up to two-thirds of the healthy populations are permanently or transiently colonized by S. aureus and CoNS. Chlorhexidine is an antiseptic agent particularly effective against Gram-positive bacteria. It is widely used for hygienic hand wash to prevent transmission of Staphylococci nosocomial infections. The plasmid-borne qacA/B, qacC, and smr genes confer resistance to cationic antiseptic agents in S. aureus and CoNS. Objectives: The objective of the current study was to characterize the antibiotic resistance and susceptibility to quaternary ammonium compounds (QACs) in methicillin-sensitive S. aureus (MSSA), methicillin-resistant S. aureus (MRSA), methicillin-sensitive coagulase-negative staphylococci (MSCoNS), and methicillin-resistant coagulase-negative Staphylococci (MRCoNS). Methods: In this study, the antibiotic susceptibility and resistance to Chlorhexidine in 120 Staphylococcal strains were evaluated by disc diffusion and Minimum inhibitory concentration (MIC) of Chlorhexidine gluconate (CHG) methods, respectively. The MICs of CHG were determined in triplicate by broth micro-dilution, and the presence of mecA, qacA/B, qacC, and smr genes was examined by PCR assay. Results: Of total 60 S. aureus isolates, 51 (85%) were MRSA, and of 60 CoNS, 7 (11.66%) were MRCoNS. The results showed that the MIC of Chlorhexidine for all 120 isolates was 1-16 _g/mL. 15 (12.5%) isolates carried qacA/B gene, 26 (21.7%) carried qacC gene, and 38 (31.7%) carried smr gene. Conclusions: Maintenance of MRSA isolates in the attendance of low amounts of antiseptics could result in the decreased susceptibility to antiseptics.

Bir üçüncü basamak hastanesindeki kronik dakriyosistit hastalarının kültür sonuçlarının klinik ve mikrobiyolojik değerlendirmesi

Objective: In this study, we aimed to evaluate the isolated strains from the patients with chronic dacryocystitis and the relationship between different anatomical areas and their antibiotic susceptibilities. Methods: Fifty patients diagnosed with chronic dacryocystitis were included. Fifty patients underwent endoscopic endonasal dacryocystorhinostomy from March 2013 to April 2014. Swab samples were obtained from conjunctiva and inferior nasal meatus before surgery, obtained from lacrimal sac during surgery. Identification and antibiotic susceptibility of the isolated strains were performed by automated Vitek version 2.0 systems (BioMeriuex Inc., Marcy-l'Etoile, France). Results: A total of 39 (78%) female and 11 (22%) male patients were operated and 150 swab samples were evaluated. Bacterial growth was detected in 136 (90.6%) culture samples. A single (n=125; 91.9%) or two different (n=11; 9.1%) microorganisms were grown on culture media. The distribution of gram-positive strains (n=91) and gram-negative strains (n=56) were 61.90% and (38.10%), respectively. The most frequently isolated gram-positive isolate was Staphylococcus. Gram-negative isolates were susceptible to third-generation cephalosporins, cefepime and carbapenems while gram-positive isolates were susceptible to vancomycin, teicoplanin and linezolide. Conclusion: For methicillin-sensitive coagulase-negative Staphylococci and methicillin-resistance coagulase-negative Staphylococci, bacterial growth demonstrated similarities among three different compartments (conjunctiva, lacrimal sac and inferior meatus). In other words, growth of these microorganisms in one location points to their proliferation in the other location or vice versa. This data can be used to guide antimicrobial therapy for these cases; but further studies are required.

Clindamycin microbial resistance in clinical isolates of Staphylococcus sp. derived from blood cultures of hospitalized patients

Introduction: Infections caused by methicillin-resistant Staphylococcus aureus (MRSA) strains have become common in hospitals, and this resistance has limited patients' treatment with beta-lactam antibiotics. Clindamycin is an important therapeutic agent for MRSA infections; however, inducible macrolide-lincosamide-streptogramin B (MLSB) resistance (iMLSB) has resulted in therapeutic failures with the use of this antimicrobial, with a consequent increase in patient mortality and length of stay. Objective: This study was carried out in order to detect phenotypes of inducible and constitutive resistance to clindamycin in blood culture samples of Staphylococcus sp. from hospitalized patients. Material and methods: A hundred bacterial samples from blood cultures of adult patients were evaluated, identified by conventional phenotypic tests, and subject to determination of susceptibility and resistance profiles with cefoxitin, erythromycin, and clindamycin discs; and to phenotypic evaluation of iMLSB resistance using the D-test. The results were interpreted in accordance with the recommendations of the Clinical and Laboratory Standards Institute (CLSI) 2014. Results: In this study, 65% of 60 bacterial strains were susceptible to cefoxitin and 35%, resistant. The constitutive MLSB (cMLSB) resistance phenotype was observed in 15.56% of the methicillin-sensitive Staphylococcus aureus (MSSA) samples, 33.33% of methicillin-sensitive coagulase-negative Staphylococcus (MSCONS), 26.67% of MRSA and 20% of methicillin-resistant coagulase-negative Staphylococcus (MRCONS), while iMLSB resistance was observed only in strains susceptible to cefoxitin, corresponding to 80% in MSSA and 20% in MSCONS. Conclusion: The D-test is a key test for the constant monitoring of the inducible resistance phenotype (which may impair the effectiveness of treatment with clindamycin), minimizing potential medication errors and adverse clinical outcomes.

A study of inducible clindamycin resistance in erythromycin resistant clinical isolates of Staphylococcus species

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

Microbiological study of therapeutic soft contact lenses used in the treatment of recurrent corneal erosion syndrome.

To determine the bacteriological spectrum of the removed therapeutic soft contact lenses (TSCLs) and to establish efficacy of prophylactic antibiotics on TSCLs used for 2 weeks for treatment of patients with recurrent corneal erosion syndrome (RCES). This study included idiopathic RCES treated using highly oxygen-permeable silicone hydrogel contact lenses (CLs), and treated 4 times per day with topical tobramycin 3% for 2 weeks. After TSCLs were applied for 2 weeks, the lenses were removed with sterile forceps under which a speculum was inserted, and placed on blood agar with the inner face down. The TSCLs were analyzed for bacterial colonization, and antibiotic susceptibility tests were performed for the isolates, using disk diffusion. Of the 40 lenses analyzed, 9 (22.5%) yielded positive cultures. Staphylococcus epidermidis was the most commonly isolated microorganism; there were five methicillin-sensitive coagulase-negative staphylococci and two methicillin-resistant coagulase-negative staphylococci. Furthermore, we found two lenses that were colonized by Enterobacter gergoviae and Citrobacter freundii. All cultured bacteria showed intermediate or complete sensitivity to ciprofloxacin, tigecycline, and tobramycin. Despite bacterial colonization in 9 CLs, no clinical signs of infectious keratitis were found in any of the patients with prophylactic topical tobramycin 3%. In case of using TSCLs for 2 weeks, tobramycin or ciprofloxacin may be useful as prophylactic topical antibiotics for preventing secondary corneal infections. Considering currently growing incidence of ciprofloxacin-resistant ocular isolates, tobramycin seems to be a reasonable prophylactic topical antibiotic susceptible broad spectrum of bacteria in clinics.

Identification of nasal bacterial flora profile and carriage rates of methicillin-resistant Staphylococcus aureus in patients with allergic rhinitis

The aim of the present study was to evaluate the effect of allergic rhinitis (AR) on the nasal flora and colonization rates of resistant microorganisms in comparison to healthy individuals. This colonization may be important in terms of AR-related disorders, the resistant microorganisms' carriage, and its complications and co-morbidities. The study was performed with two groups. The study group was composed of 54 adult patients with AR. The control group was composed of 50 healthy individuals. None of the individuals in both groups have used any antibiotics, local or systemic steroid within the last month. Composition of bacterial nasal flora and carriage rates of methicillin-resistant Staphylococcus aureus (MRSA) were evaluated with conventional methods by taking nasal smears with a swab. In the study group, methicillin-sensitive coagulase-negative staphylococci (MRCNS) were detected in 30%; whereas diphtheroids in 25%, methicillin-resistant coagulase-negative staphylococci in 13%, methicillin-sensitive S. aureus in 9%, methicillin-resistant S. aureus in 3.7%, and extended-spectrum beta lactamases-positive gram-negative bacilli (GR-ESBL+) in 3.7% were detected. In the control group, methicillin-sensitive coagulase-negative staphylococci were detected in 54%; whereas diphtheroids in 21%, methicillin-resistant coagulase-negative staphylococci in 1.5%, methicillin-sensitive S. aureus in 16%, methicillin-resistant S. aureus in 1.5%, Gr-ESBL(-) in 4%, and viridians streptococci in 3% were detected. It is found that the MRSA and MRCNS colonization is higher in patients with AR. This colonization may be important in terms of AR-related disorders, the resistant microorganisms' carriage, and its complications and co-morbidities in comparison to healthy subjects.

Bacterial Contaminants of Bandage Contact Lenses Used After Laser Subepithelial or Photorefractive Keratectomy

To compare the locations and types of bacterial contamination of bandage disposable soft contact lenses after laser subepithelial keratectomy (LASEK) and photorefractive keratectomy (PRK). Bandage disposable soft contact lenses were collected with sterile forceps from 30 eyes of 15 consecutive patients treated with LASEK (LASEK group) and 30 eyes of 15 consecutive patients who underwent PRK (PRK group) to correct myopia. Immediately after collection, each lens was cut in two parts with sterile scissors and placed onto chocolate agar with one piece outer face down and the inner face down for the other piece. The lenses were analyzed for bacterial colonization and evaluated for the amount of growth on the inner face and outer face, respectively. The antibiotic susceptibility tests were performed for the isolates using disk diffusion. Five positive cultures (16.7%) were found in LASEK group: 4 appeared in the inner face of the lens and1 appeared in the outer face. In PRK group, 2 of the 30 contact lenses (6.67%) had positive cultures; both of them appeared in the outer face of the lens. The difference of positive culture rate in the two groups was not statistically significant (χ=1.46, P=0.228). When comparing the positive colonization rate in location, the positive culture rate in the inner face of LASEK group was statistically significantly higher than that of PRK group (13.3% vs. 0%, χ=4.29, P=0.038); however, no clinical finding of infection was noted. In both groups, methicillin-sensitive coagulase-negative staphylococci (MSSCoN) were the most common isolate. Besides MSSCoN, the growth of methicillin-resistant coagulase-negative staphylococci, Corynebacterium, and Micrococcus were also present in this study. All the microorganisms were sensitive to tobramycin, which was used in conjunction with dexamethasone to treat the cases. Previous literature reports that the risk of infectious keratitis after LASEK or PRK is relatively low. However, within this study, the rate of positive cultures was relatively higher in LASEK group (16.7%) compared with that of PRK group (6.67%), especially in the inner face of the lens. The reason may be related to the procedure of keeping the epithelial flap in place, which could develop a local environment suitable for bacterial colonization and potential infection. Coagulase-negative staphylococci, a major element of the natural conjunctival flora, remain a major potentially infectious agent after LASEK and PRK.

Conjunctival sac bacterial flora isolated prior to cataract surgery

ObjectiveTo determine the trends of conjunctival sac bacterial flora isolated from patients prior to cataract surgery.Subjects and methodsThe study comprised 579 patients (579 eyes) who underwent cataract surgery. Specimens were collected by lightly rubbing the inferior palpebral conjunctival sac with a sterile cotton swab 2 weeks before surgery, and then cultured for isolation of bacteria and antimicrobial sensitivity testing. The bacterial isolates and percentage of drug-resistant isolates were compared among age groups and according to whether or not patients had diabetes mellitus, hyperlipidemia, dialysis therapy, oral steroid use, dry eye syndrome, or allergic conjunctivitis.ResultsThe bacterial isolation rate was 39.2%. There were 191 strains of Gram-positive cocci, accounting for the majority of all isolates (67.0%), among which methicillin-sensitive coagulase-negative staphylococci was the most frequent (127 strains, 44.5%), followed by methicillin-resistant coagulase-negative staphylococci (37 strains, 12.7%). All 76 Gram-positive bacillary isolates (26.7%) were from the genus Corynebacterium. Among the 16 Gram-negative bacillary isolates (5.9%), the most frequent was Escherichia coli (1.0%). The bacterial isolation rate was higher in patients >60 years old, and was lower in patients with dry eye syndrome, patients under topical treatment for other ocular disorders, and patients with hyperlipidemia. There was no significant difference in bacterial isolation rate with respect to the presence/absence of diabetes mellitus, steroid therapy, dialysis, or a history of allergic conjunctivitis. Methicillin-resistant coagulase-negative staphylococci showed a significantly higher detection rate in diabetic patients than nondiabetic patients (20.3% versus 7.0%, P < 0.05). The percentage of all isolates resistant to levofloxacin, cefmenoxime, and tobramycin was 14.0%, 15.2%, and 17.9%, respectively, with no significant differences among these drugs.ConclusionThe high bacterial isolation rate in patients >60 years old and the high methicillin-resistant coagulase-negative staphylococci isolation rate in patients with diabetes are important to consider for prevention of perioperative infections.

Incidence and risk factors of the secondary skin infections in patients with radiodermatitis.

The aim of this prospective study was to investigate the incidence and risk factors of secondary infected radiodermatitis in patients receiving radiotherapy and to determine isolated microorganisms' resistance profiles to different antimicrobial agents. The study comprised 62 patients admitted to the Regional Training and Research Hospital from January 2009 to January 2010. Radiodermatitis was graded according to the National Cancer Institute's Common Toxicity Criteria version 3.0. Potential risk factors for secondary infection were recorded and evaluated by univariate and multivariate analyses. In 62 patients, grade 1, 2, 3 and 4 radiodermatitis were observed in 33 (53.2%), 11 (17.7%), 8 (12.9%) and 10 (16.2%) patients, respectively. Skin infection secondary to radiodermatitis occurred in 14 patients (infected patients), 21.4%, 21.4% and 57.2% of whom had grade 2, 3 and 4 radiodermatitis, respectively. Forty-eight patients were found to be colonized with micoorganisms (colonized patients). In the univariate analysis, concurrent endocrine therapy and radiodermatitis grade differed significantly between infected and colonized patients (p<0.05). Multivariate analyses showed that the radiodermatitis grade was an independent risk factor for the acquisition of infection (p<0.05). The microbial pathogens isolated from patients with skin infection were seven methicillin-resistant coagulase-negative Staphylococcus (MRCNS) strains, three methicillin-resistant Staphylococcus aureus (MRSA) strains, two Candida sp., one methicillin-sensitive coagulase-negative Staphylococcus (MSCNS) strain and one methicillin-sensitive S. aureus (MSSA) strain. Staphylococci strains were more resistant to beta-lactam antibiotics. No glycopeptide resistance was found. The results of this study indicate that high-grade radiodermatitis leads to an increased risk for secondary infection of the skin with pathogens.

Development and application of a novel multiplex polymerase chain reaction (PCR) assay for rapid detection of various types of Staphylococci strains

In this study, a novel multiplex- polymerase chain reaction (PCR) for rapid detection of various staphylococci strains, including methicillin-resistant Staphylococcus aureus (MRSA), methicillin-sensitive Staphylococcus aureus, (MSSA) methicillin-resistant coagulase-negative staphylococci (MRCNS), methicillin-sensitive coagulase-negative staphylococci (MSCNS) and non-staphylococci strains, had been developed and applied. Six primers were specially designed on three target genes, which were mecA, 16S Ribosomal ribonucleic acid (rRNA) and femA. The specific amplification generated 3 bands on agarose gel, with sizes 374 bp for mecA, 542 bp for 16S rRNA and 823 bp for femA, respectively. The PCR product showed highest levels of resolution of DNA when 250 �M of dNTP, primer concentration of mecA, 16S rRNA and femA reaching 1, 1 and 3 �M respectively. No false positive amplification was observed, indicating the high specificity of the established multiplex PCR assay. Application of this multiplex-PCR had been further performed on detection for 262 MRSA and MRCNS strains with primers pairs M1 with M2 and F1 and F2. According to the results, multiplex-PCR results showed expected products for either MRSA or MRCNS strains, demonstrating the multiplex-PCR assays established in this study to be useful and powerful methods for differentiation of MRSA, MSSA, MRCNS, MSCNS and non-staphylococci strains.

Antimicrobial Resistance among Coagulase-Negative &lt;i&gt;Staphylococci &lt;/i&gt;Isolated from the First Bethune Hospital

Coagulase-negative staphylococci (CNS) are among the most frequently isolated bacterial species in clinical microbiology, and most CNS-related infections are hospital acquired. The aim of the present study was to evaluate the antibiotic resistance profiles of CNSisolated in the First Bethune Hospital. Disk diffusion method was used to study the antimicrobial resistance. The data were analyzed by WHONET 5 software according to Clinical and Laboratory Standards Institute (CLSI). The majority of 2484 strains of CNSwere collected from blood (925, 37.2%), secretions (652, 26.2%) , urine (323, 13.0%) and pus (250, 10.1%). The percentage of methicillin-resistant coagulase-negative Staphylococci (MRCNS) was 80.5％. All the CNS isolates were sensitive to vancomycin and teicoplanin. MRCNS strains were frequently resistant to multiple antibiotics. Antimicrobial resistance of MRCNS was more serious than that of methicillin-sensitive coagulase-negative Staphylococci (MSCNS). These results suggest that surveillance of antimicrobial resistance among CNS is necessary.

Detection of inducible clindamycin resistance in Staphylococcus aureus and coagulase-negative staphylococci - a study from South India

Background: Inducible clindamycin resistance is a major concern for the use of clindamycin to treat staphylococcal infections. Aims: To determine the prevalence of inducible clindamycin resistance in clinical isolates of Staphylococcus spp. and the susceptibility pattern of the isolates. Materials and Methods: A total of 300 isolates of Staphylococci spp. recovered from different clinical specimens were studied. All the Staphylococcus spp. were identified by conventional microbiological methods. Inducible clindamycin resistance was detected by double disk approximation test (Dtest).Results: Of the 300 isolates, 176 were identified as S. aureus, while 124 were coagulase negative staphylococci (CoNS). The rates of inducible clindamycin resistance in methicillin resistant S. aureus (MRSA), methicillin sensitive S. aureus (MSSA), methicillin resistant CoNS (MR-CoNS) and methicillin sensitive CoNS (MSCoNS) were 75.0%, 24%, 18.8% and 11.1%, respectively. The inducible clindamycin resistance was significantly more among MRSA compared to methicillin sensitive S. aureus (MSSA) (P value < 0.0001). Majority of the MRSA isolates were susceptible to clindamycin, vancomycin and linezolid, while most of them were resistant to erythromycin, gentamicin, ciprofloxacin, tetracycline and sulfamethoxazole-trimethoprim. Conclusion: In view of the significant in vitro inducible clindamycin resistance in Staphylococcus spp., we recommend that D test should be used as a mandatory method in microbiology laboratories to avoid misinterpretation of clindamycin result.