"Inducible clindamycin resistance in Staphylococcus aureus isolated from clinical samples"

Increasing frequency of methicillin resistant Staphylococcus aureus (MRSA) infections and changing patterns in antimicrobial resistance have led to renewed interest in the use of macrolide-lincosamide-streptogramin (MLS) antibiotics to treat such infections. Inducible macrolides, lincosamides, type B streptogramins (MLS(Bi)) resistance has to be identified to avoid clinical failure of clindamycin therapy. Hence we wanted to study the incidence of inducible clindamycin resistance in MRSA and methicillin susceptible Staphylococcus aureus (MSSA). Staphylococcus aureus was isolated in 1049 patients over a period of two years from various clinical materials. All the isolates were tested for inducible clindamycin resistance by disc diffusion induction test (D-zone test). A total of 726 MSSA and 323 MRSA were tested for the inducible clindamycin resistance (MLS(Bi)) by D-zone test. Inducible resistance to clindamycin (MLS(Bi)) where D test was positive was observed in 42.1% of MRSA and 3.4% of MSSA. Inducible resistance to clindamycin (MLS(Bi)) was found to be higher in MRSA than MSSA isolates. Clindamycin is one of the important alternative antibiotics to treat MRSA infections in resource poor countries. To avoid treatment failure with clindamycin, prior D testing is necessary.     

Comparison of both clinical features and mortality risk associated with bacteremia due to community-acquired methicillin-resistant Staphylococcus aureus and methicillin-susceptible S. aureus.

BACKGROUND: The majority of research about community-acquired methicillin-resistant Staphylococcus aureus (CA-MRSA) infection has focused on skin and soft-tissue infections. No literature has been published on the clinical features and outcomes of adult patients with CA-MRSA bacteremia in comparison with patients with community-acquired methicillin-susceptible S. aureus (CA-MSSA) bacteremia. METHODS: From 1 January 2001 through 31 December 2006, the demographic data and outcome of 215 consecutive adult patients admitted to a tertiary care center in Taiwan with S. aureus bacteremia (age, >16 years) who fulfilled the criteria for community-acquired S. aureus bacteremia were collected for analysis. RESULTS: The mean age (+/-SD) was 56.8+/-20.5 years. There were 30 patients (14%) with CA-MRSA bacteremia and 185 (86%) patients with CA-MSSA bacteremia. Cutaneous abscess (odds ratio, 5.46; 95% confidence interval, 1.66-17.94) and necrotizing pneumonia (odds ratio, 24.81; 95% confidence interval, 2.63-234.03) were the independent predictors of CA-MRSA bacteremia; endovascular infection was the only independent predictor of CA-MSSA bacteremia. After Cox regression analysis, the independent significant risk factors for 30-day mortality included increased age, shock, and thrombocytopenia (<100,000 cells/microL). After adjustment, the day 30 mortality of patients with CA-MRSA bacteremia was not significantly higher than that of patients with CA-MSSA bacteremia (adjusted hazard ratio, 1.01; 95% confidence interval, 0.30-3.39; P = .986). Most (92%) of 25 available CA-MRSA isolates were multilocus sequence typing 59. CONCLUSIONS: The number of adult patients with CA-MRSA bacteremia increased with time, and the disease was associated with more necrotizing pneumonia and cutaneous abscess but less endovascular infection than was CA-MSSA bacteremia. Patients with CA-MRSA bacteremia did not have higher mortality than did patients with CA-MSSA, even though most of the patients with CA-MRSA bacteremia did not receive empirical glycopeptide therapy.     

Prevalence of methicillin-resistant Staphylococcus aureus among university students in Thailand

We studied the prevalence of methicillin sensitive Staphylococcus aureus (MSSA) and methicillin resistant Staphylococcus aureus (MRSA) nasal colonization among healthy young Thai adults. MSSA nasal colonization was found in 30 of 200 subjects (15%). The prevalence of MRSAnasal carriage was 1% (2 of 200) detected by cefoxitin/oxacillin disk diffusion and oxacillin salt screening methods. These carriers were associated with health care risk factors. The two MRSA isolates were mecA positive, SCCmec type II. All S. aureus isolates were tested for antibiotic resistance. Their resistance rates to penicillin, erythromycin, clindamycin, oxacillin and cefoxitin were 96.7, 26.7, 26.7, 6.7 and 6.7%, respectively. All MSSA and MRSA isolates were susceptible to gentamicin, chloramphenicol, trimethoprim/sulfamethoxazole, rifampicin, linezolid, fusidic acid, mupirocin, ciprofloxacin and vancomycin. The results of this first study of MRSA nasal colonization among healthy young Thai adults suggests MRSA is present in the Thai community.     

社区相关性耐甲氧西林金黄色葡萄球菌感染的流行现状及微生物学特征

耐甲氧西林金黄色葡萄球菌是院内感染常见病原菌之一,也可导致社区相关性感染。社区相关性耐甲氧西林金黄色葡萄球菌(CA-MRSA)与医院相关性耐甲氧西林金黄色葡萄球菌(HA-MRSA)在很多方面存在差异,其对多数非β-内酰胺类抗菌药敏感,大多携带杀白细胞素,多为葡萄球菌染色体mec基因盒Ⅳ或Ⅴ型。CA-MRSA毒力更强,并...     

Linezolid resistance in a clinical isolate of Staphylococcus aureus

The new oxazolidinone antimicrobial, linezolid, has been approved for the treatment of infections caused by various gram-positive bacteria, including meticillin-resistant Staphylococcus aureus (MRSA) and vancomycin-resistant enterococci (VRE). Although instances of linezolid resistance in VRE have been reported, resistance has not been encountered among clinical isolates of S aureus. We have characterised an MRSA isolate resistant to linezolid that was recovered from a patient treated with this agent for dialysis-associated peritonitis.     

Emergence of community-associated methicillin-resistant Staphylococcus aureus USA 300 clone as a cause of health care-associated infections among patients with prosthetic joint infections

BACKGROUND: Community-associated methicillin-resistant Staphylococcus aureus (CA-MRSA) has emerged as an important cause of staphylococcal infections, but there have been little data on whether CA-MRSA causes health care-associated infections. METHODS: A case-control study was performed to identify risk factors for prosthetic joint infections (PJI). Antibiograms of isolates associated with PJI were reviewed. Molecular typing of available MRSA isolates was done using pulsed field gel electrophoresis (PFGE). Nares cultures of health care workers who provided care to those orthopedic patients were obtained. RESULTS: Over a 13-month period (January 2003-January 2004), 9.5% of patients with prosthetic hip (THA) or knee (TKA) joint surgery developed PJI (7 TKA and 2 THA). The mean time to development of PJI was 20 days. Five infections were caused by CA-MRSA and 3 by methicillin-susceptible S aureus; one was culture negative. All CA-MRSA isolates had identical antibiograms (resistant to beta-lactams and erythromycin; susceptible to clindamycin, trimethoprim-sulfamethoxazole, rifampin, gentamicin, levofloxacin, and vancomycin). Molecular typing of 2 available CA-MRSA isolates revealed that these were the USA300 clone; these isolates were PVL+ and carried SCCmec IV. CA-MRSA was not recovered from nares cultures from 31 health care workers. In multivariate analysis, TKA (OR, 8.1; 95% CI: 1.3-48.1) and surgery time >180 minutes (OR, 7.4; 95% CI: 1.4-39.6) were associated with PJI. CONCLUSION: We have demonstrated that the CA-MRSA USA300 clone is no longer just a cause of community-acquired infections but has also emerged as a cause of health care-associated infections, causing PJI at our institution.     

What is community-associated methicillin-resistant Staphylococcus aureus?

BACKGROUND: A community-associated methicillin-resistant Staphylococcus aureus (CA-MRSA) infection has been defined as an MRSA infection in a patient who lacks specific risk factors for healthcare exposure. We sought to determine whether the absence or presence of these risk factors still predicts the phenotypic or genotypic characteristics of MRSA strains. METHODS: All clinical MRSA isolates were prospectively collected at the University of Chicago Hospitals from July 2004 through June 2005. Patients were interviewed and/or their medical records were reviewed. Isolates underwent genotyping and susceptibility testing. Data on patients and isolates were stratified in accordance with 8 frequently cited criteria for the identification of CA-MRSA and compared for concordance. RESULTS: Among 616 unique patients from whom MRSA isolates were recovered, 404 (65.6%) had risk factors for healthcare exposure. Of the 404 isolates recovered from these patients, 166 (41.1%) were clindamycin susceptible, 190 (47.0%) carried staphylococcal cassette chromosome mec (SCCmec) type IV, 145 (35.9%) carried the Panton-Valentine leukocidin genes (PVL+), and 162 (40.1%) were identified as sequence type (ST) 8 by multilocus sequence typing (MLST), all of which are characteristics commonly attributed to CA-MRSA strains. CONCLUSIONS: Association with the healthcare environment now has little predictive value for distinguishing patients with infection due to multidrug resistant MRSA isolates from those infected by CA-MRSA isolates, that is, isolates that are clindamycin-susceptible, PVL+, ST8, and/or contain SCCmec type IV. Defining CA-MRSA by the absence of risk factors for healthcare exposure greatly underestimates the burden of epidemic CA-MRSA disease.     

Community-associated methicillin-resistant Staphylococcus aureus infections in men who have sex with men: A case series

BACKGROUND: The purpose of the present study was to describe the clinical characteristics and management of community-associated methicillin-resistant Staphylococcus aureus (CA-MRSA) infections among a cohort of men who have sex with men. PATIENTS AND METHODS: A retrospective chart review was conducted of patients with culture-proven MRSA at Maple Leaf Medical Clinic (Toronto, Ontario) between November 2004 and December 2005. Cases were identified by individual physicians and by queries in the clinical management system. A standard data collection form was used to record patient demographics, potential risk factors for MRSA and course of illness. When available, antimicrobial sensitivities were recorded. DNA fingerprinting using pulsed-field gel electrophoresis, and genetic analysis for SCCmec typing and detection of the Panton-Valentine leukocidin cytotoxin were performed on six available isolates. RESULTS: Seventeen patients with MRSA infection were identified, 12 (71%) of whom were HIV-positive. The most common clinical presentation was abscess (35%), followed by furuncle (17%), folliculitis (17%), cellulitis (17%) and sinusitis (12%). The majority of MRSA isolates were resistant to ciprofloxacin (92%) and levofloxacin (77%). All isolates were susceptible to trimethoprim-sulfamethoxazole, rifampin, linezolid, gentamicin and clindamycin, while the majority were susceptible to tetracycline (80%). All six isolates tested were SCCmec type IVa-positive and Panton-Valentine leukocidin-positive, and had fingerprint patterns consistent with the CMRSA-10 (USA300) clone. CONCLUSION: The present study describes the clinical presentation and management of CA-MRSA infections occurring in Toronto among men who have sex with men. The infections appear to have been caused by CMRSA-10, which has caused the majority of CA-MRSA outbreaks elsewhere.     

Methicillin-resistant Staphylococcus aureus: a new community-acquired pathogen?

PURPOSE OF REVIEW: The main goal of this review is to describe the emergence of methicillin-resistant Staphylococcus aureus (MRSA) as a community pathogen. RECENT FINDINGS: Community-acquired MRSA has emerged as an important infection in the community setting. It has primarily been associated with skin and soft-tissue infections, but can also cause severe pulmonary infections, including pneumonia and empyema. Community-acquired MRSA is typically more susceptible to a wider class of antibiotics than healthcare-associated MRSA. Community-acquired MRSA is also more virulent compared with healthcare-associated MRSA isolates. Community-acquired MRSA usually contains the gene encoding Panton-Valentive leukocidin, which is a toxin that creates lytic pores in the cell membranes of neutrophils and induces the release of neutrophil chemotactic factors that promote inflammation and tissue destruction. The optimal antibiotic treatment for Panton-Valentive leukocidin-positive community-acquired MRSA is unknown; however, antibiotics with activity against MRSA and the ability to inhibit toxin production may be optimal (linezolid or clindamycin for susceptible isolates). SUMMARY: Clinicians should be aware of the emergence of community-acquired MRSA as an important cause of serious infections arising in the community setting. Appropriate antibiotic therapy should be initiated as soon as infection with this pathogen is suspected.     

Determining of antibiotic resistance profile in Staphylococcus aureus isolates

ObjectiveTo determine the pattern of antibiotic resistance among Staphylococcus aureus (S. aureus) isolates from clinical specimens and to identify community-acquired methicillin-resistant Staphylococcus aureus (CA-MRSA) in specimens that have been collected from patients referring to one of the hospitals of Ahvaz.MethodsS. aureus isolates from a hospital in Ahvaz were screened for resistance to various antibiotics including methicillin. The susceptibility of the isolates was determined by Kirby-Bauer disc diffusion method. The MRSA was also treated with ethidium bromide to find the origin of resistance.ResultsAmong the bacterial isolates, all of 11 S. aureus were resistant to methicillin and cefixime, 2 were resistant to ciprofloxacine, 6 were resistant to tetracycline and the reminder were sensitive or intermediate to other antibiotics. The treated isolates were reminded resistant to methicillin and this suggested that the plasmid was not the origin of resistance in these isolates.ConclusionsThese results showed that infection due to MRSA is widespread in Ahvaz and with respect to the spread of vancomycin resistance among MRSA and appearance of overwhelming infections. It is necessary to identify continuously the profile of antibiotic resistance among S. aureus isolates in other regions and finding appropriate antibiotic for infection control and eradication.     

Staphylococcal resistance revisited: community-acquired methicillin resistant Staphylococcus aureus--an emerging problem for the management of skin and soft tissue infections

PURPOSE OF REVIEW: In the community non-localized or deep staphylococcal skin and soft tissue infections are typically managed with beta-lactamase stable penicillins. The aims of this review are (1) to evaluate the evidence for the emergence of new strains of community-acquired methicillin resistant Staphylococcus aureus (MRSA), (2) to identify the reasons for their significant association with cutaneous infections, and (3) to consider how they arose and how big a threat they pose to the management of such infections outside hospitals. RECENT FINDINGS: MRSA are emerging as significant community pathogens, especially in previously healthy children with no recognizable risk factors, and are predominantly associated with skin and soft tissue infections (especially abscesses and cellulitis). When present, risk factors are generally similar to those for infection with methicillin susceptible S. aureus. The MRSA isolates associated with such infections may not be entirely 'new', but could represent the displacement of some hospital clones (e.g. EMRSA-15 or variants thereof) to the community as well as the de-novo generation of novel MRSA clones by multiple horizontal transmissions of the mecA gene into methicillin susceptible S. aureus with different genetic backgrounds, some of which are already circulating globally. Community-acquired MRSA from diverse locations are non multiresistant and almost always contain the novel type IV SCCmec commonly found in coagulase-negative staphylococci, but also in hospital-associated gentamicin susceptible MRSA from France, the paediatric clone and in EMRSA-15. SUMMARY: More local data on CA-MRSA infections are needed so that dermatologists and community physicians can assess the risk of such infections amongst their patients and avoid the inappropriate administration of beta-lactams. No simple change in prescribing practices will entirely alleviate selective pressure for the spread of community-acquired MRSA and not exacerbate resistance in pyogenic streptococci, commonly found together with S. aureus in skin and soft tissue infections. The importance of hygiene in preventing the spread of community-acquired MRSA in the community must be reemphasized.     

Linezolid resistance in sequential Staphylococcus aureus isolates associated with a T2500A mutation in the 23S rRNA gene and loss of a single copy of rRNA

Linezolid is an important therapeutic option for infections caused by resistant gram-positive bacteria. We report the characterization of sequential methicillin-resistant Staphylococcus aureus (MRSA) bloodstream isolates that developed resistance in a patient treated with a prolonged course of linezolid. Analysis of this series of clinical MRSA isolates detected, in the resistant isolates, the presence of a T2500A mutation in the domain V region of the 23S rRNA gene. In addition, the loss of a single copy of the 23S rRNA gene was found in 2 of the resistant isolates. As a result of these 2 factors, the proportion of mutant : wild-type 23S rRNA genes increased in association with an increase in the minimum inhibitory concentration of linezolid. The most recent isolate of this series was recovered 7 months after the patient discontinued linezolid and demonstrated reversion to a susceptible phenotype associated with a loss of the T2500A mutation.     

遏制金黄色葡萄球菌广泛耐药性以及相关转化医学平台的搭建

不断出现的耐甲氧西林金黄色葡萄球菌(methicillin-resistant Staphylococcus aureus,MRSA)广泛耐药性是医疗机构和社区健康的主要威胁。社区获得性MRSA(community-acquired MRSA,CA-MRSA)是顽固的传染性致病菌,感染率和病死率高。因MRSA不但耐受所有β-内酰胺类抗生素,且具有获得外源毒力抗药基因的能力,临床治疗方法很有限。近来的研究表明CA-MRSA分离株比医院获得性MRSA更具毒力,更易传播,且具广泛耐药性,临床上只有少数几种抗生素有效(如万古霉素)。尽管已对CA-MRSA的进化机制有了一些了解,但其传播的分子过程、毒力的相关知识及治疗手段还相当有限,对医院和社区相关MRSA感染过程中的分子因素所知甚少,目前的治疗方法及抗生素的研发远落后于MRSA的进化。本文对近3年来的基础研究、成功的临床案例及细菌广泛耐药性遏制策略进行综述,以期提供关于转化医学的发展趋势和平台构建原则,从而应对包括MRSA在内的耐药致病菌。     

Diagnosis and management of Staphylococcus aureus infections of the skin and soft tissue

Infections involving the skin and soft tissue are common and range from superficial, localized and sometimes self-limiting infections to deep, rapidly spreading and potentially life-threatening infections. Skin infections caused by Staphylococcus aureus include primary pyodermas, while those involving the soft tissues include cellulitis and pyomyositis. Surgical site infections and infections in intravenous drug users are also commonly caused by S. aureus. The severity of the infection determines the choice of treatment. There are few studies that have critically appraised the use of antibiotics in skin and soft tissue infections, and most guidelines are based on expert opinion. The beta-lactam group of antibiotics are the mainstay of treatment for methicillin-susceptible S. aureus infections. For methicillin-resistant S. aureus (MRSA) infections, both with community-acquired and hospital-acquired strains--which are becoming an increasing problem--the antibiotic choice is determined by local susceptibility patterns. Macrolides, clindamycin and cotrimoxazole are options for community-acquired MRSA, while vancomycin is reserved for treatment of infections caused by multiresistant MRSA strains and for patients with suspected endocarditis or severe sepsis. Although a number of the newer antibiotics such as linezolid and quinopristin/dalfopristin have been shown to have good activity against MRSA, these agents should only be used with specialist advice.     

Epidemiological and molecular characterization of community and hospital acquired Staphylococcus aureus strains prevailing in Shenyang,Northeastern China

In order to obtain adequate information for the treatment of methicillin resistant Staphylococcus aureus (MRSA) infections, it is crucial to identify trends in epidemiological and antimicrobial resistance patterns of local S. aureus strains. Community and hospital acquired S. aureus isolates (n = 202) were characterized using staphylococcal cassette chromosome mec (SCCmec) typing, pulse field gel electrophoresis (PFGE) analysis, spa typing and minimal inhibitory concentration (MIC) determination. The prevalence of the Panton-Valentine leukocidine (pvl) and several antibiotic resistance genes among the isolates were also detected by PCR. All of the S. aureus isolates were susceptible to vancomycin, daptomycin and linezolid. Three hospital isolates were resistant to teicoplanin while 14 showed intermediate resistance to teicoplanin. The resistance patterns of community-acquired MRSA (CA-MRSA) isolates to other antimicrobials were similar to those of hospital-acquired MRSA (HA-MRSA) isolates except for clindamycin and gentamicin. There was excellent correlation between phenotypes and genotypes in the determination of S. aureus resistance to erythromycin, gentamicin, and tetracycline. The SCCmec type II and SCCmec type IV were the predominant types detected in hospital and community isolates, respectively. The most frequently encountered spa types were t002 and t030 both in HA- and CA-MRSA isolates. Pulsotype A was the most predominant pulsotype identified among the isolates tested, followed by pulsotype B. Seventy-two hospital isolates (19 HA-MRSA and 53 HA-MSSA) and 10 CA-MRSA were positive for the pvl gene. This study shows that the combination of susceptibility testing and various molecular methods has provided useful information on the antibiotic resistance and molecular diversity of S. aureus in a specific region of China. The high proportion of pvl positive MSSA and MRSA isolates observed in this study indicates that adequate measures are needed to curtail the spread of those MRSA and MSSA clones prevailing both in hospital and the community.     

A novel methicillin-resistance cassette in community-acquired methicillin-resistant Staphylococcus aureus isolates of diverse genetic backgrounds

Until recently, it has been unclear whether community-acquired (CA) methicillin-resistant Staphylococcus aureus (MRSA) isolates represent the spread of hospital MRSA isolates into the community. In 2 CA-MRSA isolates, a novel genetic element, designated staphylococcal cassette chromosome mec (SCCmec) type IV, was found; it differs from SCCmec types I-III in its small size and absence of non-beta-lactam genetic-resistance determinants. To study the prevalence of type IV SCCmec, polymerase chain reaction characterization of SCCmec was performed on DNA from 12 CA-MRSA isolates. The 12 CA-MRSA isolates were from diverse genetic backgrounds, as evidenced by their stratification into 5 pulsed-field gel electrophoresis types, 4 coagulase types, and 2 ribotypes. Eleven of the 12 isolates contained the novel SCCmec type IV element. Ten were resistant only to beta-lactam antibiotics. SCCmec type IV is present on the genome of CA-MRSA isolates. Its relatively small size and presence in isolates of diverse genetic backgrounds suggest that it may spread among S. aureus isolates.     

社区相关性甲氧西林耐药金黄色葡萄球菌:一个值得关注的病原体

社区相关性MRSA近年来逐渐为人们所重视,作为引起医院外感染的重要病原体之一,近年的研究表明其发病率呈不断上升的趋势,与传统的导致院内感染的MRSA相比,社区相关性MRSA有其独特的流行病学特点、发病机制和耐药机制。制定合理的治疗和预防措施显得格外重要。     

Five cases of bacterial endocarditis after furunculosis and the ongoing saga of community-acquired methicillin-resistant Staphylococcus aureus infections

Bacterial endocarditis secondary to Panton-Valentine leukocidin producing community-acquired methicillin-resistant Staphylococcus aureus (MRSA) infections is rare. We report 5 previously healthy patients who presented with endocarditis after developing furunculosis due to CA-MRSA. A retrospective chart review of all patients with MRSA positive blood cultures was conducted over a 12-month period. Patients with multiple positive blood cultures within 72 h of admission and who had no risk factors for MRSA acquisition were included. Modified Duke's criteria were used to define bacterial endocarditis. PCR detection of Panton-Valentine leukocidin (PVL) genes as well as SCCmec typing was performed. In addition, strain typing of MRSA isolates was performed utilizing pulsed-field gel electrophoresis. Five out of a total of 193 patients had features consistent with CA-MRSA infections and met modified Duke's criteria for bacterial endocarditis. Blood culture isolates were found to be PVL gene positive and carried the type IV SCCmec element. PFGE confirmed that skin isolate was identical to the isolate cultured from his blood. Bacterial endocarditis in patients with CA-MRSA furunculosis is an emerging entity. In areas where CA-MRSA skin infections are prevalent, inappropriate initial antibiotics remain a major problem and may result in significant morbidity.     

Community-acquired methicillin-resistant Staphylococcus aureus infections in a south Indian city

There are increasing numbers of reports of community-acquired Staphylococcus aureus being resistant to methicillin. The present study was undertaken as no such reports are available for the developing nations. In a prospective study, between June to December 2001, at the Karnataka Institute of Medical Sciences, Hubli, Karnataka, India, methicillin-resistant S. aureus (MRSA) isolates were tested for clindamycin-susceptibility, a surrogate marker for community-acquired strains. Patients with clindamycin-susceptible isolates were interviewed to determine if they had acquired them in the community and also to identify any risk factors. Of the 116 patients with S. aureus infection, 18.1% had infection with methicillin-resistant strains. Clindamycin-susceptible MRSA accounted for 61.9% of cases. Among these, 46.1% patients were confirmed to have acquired the MRSA from the community, based on inclusion criteria. The community-acquired MRSA were susceptible to multiple antibiotics, as compared to nosocomial isolates. Except for one patient with diabetes mellitus, no other patient had any known risk factor for acquiring MRSA. As significant numbers of MRSA infections are being acquired from the community, treatment options for S. aureus infections may need to be reviewed. Effective infection control programs for the community should be considered to prevent the spread of these infections.     

Phenotypic detection of constitutive and inducible clindamycin resistance in clinical isolates of Staphylococcus aureus and coagulase negative Staphylococcus on routine susceptibility plate

Increasing frequency of methicillin resistant Staphylococcus aureus infections and changing patterns in antimicrobial resistance have led to renewed interest in the use of macrolidelincosamide-streptogramin antibiotics. However therapy may fail either due to constitutive or inducible resistance. This study was undertaken to detect different phenotypes including inducible clindamycin resistance in clinical isolates of Staphylococcus aureus and coagulase negative Staphylococcus. Four hundred sixty five Staphylococcus aureus and 84 coagulase negative Staphylococci isolated from different clinical specimens were included in the study. On routine susceptibility testing plate clindamycin (2 microg) disk was placed at a distance of 15mm towards the centre from a peripherally placed erythromycin (15 microg) disk. Fisher exact test was used for statistical analysis. Out of 465 Staphylococcus aureus isolates, 237 (50.96%) were methicillin sensitive (MSSA) and 228 (49.03%) methicillin resistant (MLS(B)c).Over all 118 (25.37%) isolates showed constitutive resistance (MLS(B)c), 70 (15.05%) inducible clindamycin resistance, 143 (30.75%) MS(B) phenotype and 134 (28.81%) were susceptible to both erythromycin as well as clindamycin. Constitutive and inducible resistance to clindamycin were significantly higher in MRSA than MSSA (P=0.0000 and 0.0001 respectively). Out of 84 isolates of coagulase negative Staphylococci, 43 (51.19%) were methicillin sensitive (MSCNS) and 41(48.80%) methicillin resistant (MRCNS). Constitutive MLS(B) resistance was detected in 32 (38.09%), inducible clindamycin resistance 10 (11.90%), MS(B) phenotype 27 (32.14%) and 15 (17.85%) were susceptible to both erythromycin and clindamycin. Performing D test on a routine susceptibility plate saves material, manpower and time as inducible resistance can be reported simultaneously along with other susceptibility results.