Coagulase-negative staphylococci: a 20-year study on the antimicrobial resistance profile of blood culture isolates from a teaching hospital

ABSTRACT The increasing rates of nosocomial infection associated with coagulase-negative staphylococci (CoNS) were the rationale for this study, aiming to categorize oxacillin-resistant CoNS species recovered from blood culture specimens of inpatients at the UNESP Hospital das Clínicas in Botucatu, Brazil, over a 20-year period, and determine their sensitivity to other antimicrobial agents. The mecA gene was detected in 222 (74%) CoNS samples, and the four types of staphylococcal chromosomal cassette mec (SCCmec) were characterized in 19.4%, 3.6%, 54.5%, and 14.4% of specimens, respectively, for types I, II, III, and IV. Minimal inhibitory concentration (MIC) values to inhibit 50% (MIC50) and 90% (MIC90) of specimens were, respectively, 2 and >256 µL/mL for oxacillin, 1.5 and 2 µL/mL for vancomycin, 0.25 and 0.5 µL/mL for linezolid, 0.094 and 0.19 µL/mL for daptomycin, 0.19 and 0.5 µL/mL for quinupristin/dalfopristin, and 0.125 and 0.38 µL/mL for tigecycline. Resistance to oxacillin and tigecycline and intermediate resistance to quinupristin/dalfopristin were observed. Eight (2.7%) of all 300 CoNS specimens studied showed reduced susceptibility to vancomycin. Results from this study show high resistance rates of CoNS to antimicrobial agents, reflecting the necessity of using these drugs judiciously and controlling nosocomial dissemination of these pathogens.

Matrix-assisted laser desorption ionization-time of flight: a promising alternative method of identifying the major coagulase-negative Staphylococci species

Abstract INTRODUCTION. This study aimed to evaluate different methods for differentiation of species of coagulase-negative staphylococci (CoNS) that caused infections in hospitalized immunocompromised patients. METHODS. A total of 134 CoNS strains were characterized using four different methods. RESULTS. The results of matrix assisted laser desorption/ionization mass spectrometry (MALDI-TOF MS) analysis were in complete agreement with those of tuf gene sequencing (kappa index = 1.00). The kappa index of Vitek 2® Compact analysis was 0.85 (very good) and that of the conventional method was 0.63 (moderate). CONCLUSIONS . MALDI-TOF MS provided rapid and accurate results for the identification of CoNS (134; 100%).

Evaluation of BD MAX Staph SR Assay for Differentiating Between Staphylococcus aureus and Coagulase-Negative Staphylococci and Determining Methicillin Resistance Directly From Positive Blood Cultures

BACKGROUND: We evaluated the performance of the BD MAX StaphSR Assay (SR assay; BD, USA) for direct detection of Staphylococcus aureus and methicillin resistance not only in S. aureus but also in coagulase-negative Staphylococci (CNS) from positive blood cultures. METHODS: From 228 blood culture bottles, 103 S. aureus [45 methicillin-resistant S. aureus (MRSA), 55 methicillin-susceptible S. aureus (MSSA), 3 mixed infections (1 MRSA+Enterococcus faecalis, 1 MSSA+MRCNS, 1 MSSA+MSCNS)], and 125 CNS (102 MRCNS, 23 MSCNS) were identified by Vitek 2. For further analysis, we obtained the cycle threshold (Ct) values from the BD MAX system software to determine an appropriate cutoff value. For discrepancy analysis, conventional mecA/mecC PCR and oxacillin minimum inhibitory concentrations (MICs) were determined. RESULTS: Compared to Vitek 2, the SR assay identified all 103 S. aureus isolates correctly but failed to detect methicillin resistance in three MRSA isolates. All 55 MSSA isolates were correctly identified by the SR assay. In the concordant cases, the highest Ct values for nuc, mecA, and mec right-extremity junction (MREJ) were 25.6, 22, and 22.2, respectively. Therefore, we selected Ct values from 0-27 as a range of positivity, and applying this cutoff, the sensitivity/specificity of the SR assay were 100%/100% for detecting S. aureus, and 97.9%/98.1% and 99.0%/95.8% for detecting methicillin resistance in S. aureus and CNS, respectively. CONCLUSIONS: We propose a Ct cutoff value for nuc/mec assay without considering MREJ because mixed cultures of MSSA and MRCNS were very rare (0.4%) in the positive blood cultures.

Blood Culture Proven Early Onset Sepsis and Late Onset Sepsis in Very-Low-Birth-Weight Infants in Korea

Neonatal sepsis remains one of the most important causes of death and co-morbidity in very-low-birth-weight (VLBW) infants. The aim of this study was to determine the current incidences of early-onset sepsis (EOS) and late-onset sepsis (LOS), the distribution of pathogens, and the impact of infection on co-morbidities in VLBW infants. We analyzed the data including sepsis episode from 2,386 VLBW infants enrolled in Korean Neonatal Network from January 2013 to June 2014. We defined EOS as a positive blood culture occurring between birth and 7 days of life and LOS after 7 days of life. Sepsis was found in 21.1% of VLBW infants. The risk of sepsis was inversely related to birth weight and gestational age. EOS was found in only 3.6% of VLBW infants, however the mortality rate was as high as 34.1%. EOS was associated with the increased odds for bronchopulmonary dysplasia and intraventricular hemorrhage. The vast majority of EOS was caused by Gram-positive organisms, particularly coagulase-negative staphylococci (30.6%). LOS developed in 19.4% of VLBW infants with a 16.1% mortality rate. Pathogens in LOS were dominated by coagulase-negative staphylococci (38.3%). Twenty-five percent and fifty percent of first LOS episode occurred after 12 days and 20 days from birth, respectively. Younger and smaller VLBW infants showed the earlier occurrence day for the 25% of first LOS episode. This study provides a recent nationwide epidemiology of sepsis in VLBW infants in Korea. Based on this study, successful strategies to reduce infections would improve survival and reduce morbidity.

Staphylococcus coagulasa-negativa clínicamente significativos: Especies más frecuentes y factores de virulencia / Clinically significant coagulase-negative staphylococci: Most frequent species and virulence factors

Coagulase-negative staphylococci have emerged as responsible for a large number of infections. However, it is often difficult to assess its pathogenic role or to discard it as a contaminant. Aim: The goal of this study was to identify clinically significant coagulase-negative staphylococci to the species level and their virulence factors. Isolates came from patients consulting at the San Roque Laboratory from 2009 to 2011. Material and Methods: Species identification was performed by De Paulis et al simplified method. Production of biofilm, hemolysins, lipases, lecithinases and DNase were determined by conventional methods; methicillin-resistance by diffusion method and mecA and Panton-Valentine genes, by multiplex PCR. Results: Out of 64 isolates, 40.6% were S. epidermidis; 20.3%, S. haemolyticus, and 15.6%, S. lugdunensis. Biofilm production was detected in 73.1% of S. epidermidis, 53.8% of S. haemolyticus and 40% of S. lugdunensis. mecA gene was identified in 69.2% of S. epidermidis, 92.3% of S. haemolyticus and none of S. lugdunensis. 83% of mecA (+) S. epidermidis isolates were biofilm producers as compared to 50% of the mecA (-). Conclusion: The frequency of S. lugdunensis, the most virulent coagulase-negative staphylococci species, was relatively high. The main virulence factor in S. epidermidis was biofilm production, being higher in those resistant to methicillin.

Staphylococcus coagulasa-negativa ha emergido como responsable de un gran número de infecciones. No obstante, con frecuencia es difícil asegurar su rol patógeno o descartarlo como contaminante. Objetivo: Estudiar a nivel de especies Staphylococcus coagulasa-negativa clínicamente significativos y sus factores de virulencia, de aislados provenientes de pacientes del Laboratorio San Roque de Asunción, Paraguay entre los años 2009 y 2011. Material y Métodos: Para la identificación de especies fue utilizado el método simplificado de De Paulis y cols. La producción de biopelícula, hemolisinas, lipasas, lecitinasas, AD-Nasa, fue determinada por métodos convencionales; la resistencia a meticilina por difusión y los genes mecA y Panton-Valentine por RPC múltiple. Resultados: De 64 aislados, 40,6% correspondió a S. epidermidis, 20,3% S. haemolyticus y 15,6% S. lugdunensis. La producción de biopelícula fue detectada en S. epidermidis en 73,1%, S. haemolyticus 53,8% y S. lugdunensis 40%. El gen mecA fue identificado en 69,2% de S. epidermidis, 92,3% de S. haemolyticus y en ninguno de S. lugdunensis. El 83% de S. epidermidis mecA (+) fue productor de biopelícula en comparación a 50% de los mecA (-). Conclusión: La frecuencia de S. lugdunensis, una de las especies más virulentas de Staphylococcus coagulasa-negativa fue relativamente alta; y el principal factor de virulencia en S. epidermidis fue la producción de biopelícula, siendo mayor en los resistentes a meticilina.

Prevalence of resistance phenotypes in Staphylococcus aureus and coagulase-negative isolates of venous ulcers of primary healthcare patients / Prevalência de fenótipos de resistência em Staphylococcus aureus e coagulase negativos isolados de úlceras venosas de pessoas atendidas na atenção primária

INTRODUCTION: In venous ulcers, the presence of Staphylococcus aureus and coagulase-negative staphylococcus resistance phenotypes can aggravate and limit the choices for treatment. METHODS: Staphylococcus isolated from 69 patients (98 ulcers) between October of 2009 and October of 2010 were tested. The macrolide, lincosamide, streptogramin B (MLS B) group resistance phenotype detection was performed using the D-test. Isolates resistant to cefoxitin and/or oxacillin (disk-diffusion) were subjected to the confirmatory test to detect minimum inhibitory concentration (MIC), using oxacillin strips (E-test®). RESULTS: The prevalence of S. aureus was 83%, and 15% of coagulase-negative staphylococcus (CoNS). In addition were detected 28% of methicillin-resistant Staphylococcus aureus (MRSA) and 47% of methicillin-resistant coagulase-negative staphylococcus (MRCoNS). Among the S. aureus, 69.6% were resistant to erythromycin, 69.6% to clindamycin, 69.6% to gentamicin, and 100% to ciprofloxacin. Considering the MRSA, 74% were highly resistant to oxacillin, MIC ≥ 256µg/mL, and the MLS Bc constitutive resistance predominated in 65.2%. Among the 20 isolates sensitive to clindamycin, 12 presented an inducible MLS B phenotype. Of the MRCoNS, 71.4%were resistant to erythromycin, ciprofloxacin and gentamicin. Considering the isolates positive for β-lactamases, the MIC breakpoint was between 0.5 and 2µg/mL. CONCLUSIONS: The results point to a high occurrence of multi-drug resistant bacteria in venous ulcers in primary healthcare patients, thus evidencing the need for preventive measures to avoid outbreaks caused by multi-drug resistant pathogens, and the importance of healthcare professionals being able to identifying colonized versus infected venous ulcers as an essential criteria to implementing systemic antibacterial therapy.

INTRODUÇÃO: Em úlceras venosas, a presença de Staphylococcus aureus e coagulase negativo com fenótipos de resistência pode constituir fator agravante e limita as opções terapêuticas. MÉTODOS: Foram avaliados estafilococos isolados de 69 pacientes, representando 98 úlceras no período de outubro de 2009 a outubro de 2010. A detecção fenotípica da resistência ao grupo macrolide, lincosamide, streptogramin B (MLS B) foi realizada pelo D-test. Isolados resistentes a cefoxitina e/ou oxacilina (disco-difusão) foram submetidos ao teste confirmatório para detecção da minimum inhibitory concentration (MIC), empregando fitas de oxacilina (E-test®). RESULTADOS: A prevalência de S. aureus foi de 83% e de 15% de coagulase-negative staphylococcus (CoNS). Identificou-se 28% de methicillin-resistant Staphylococcus aureus (MRSA) e 47% de methicillin-resistant coagulase-negative staphylococcus (MRCoNS). Entre o S. aureus, 69,6% apresentaram resistência a eritromicina, 69,6% a clindamicina, 69,6% a gentamicina e 100% a ciprofloxacina. Setenta e quatro por cento dos MRSA apresentaram elevado nível de resistência a oxacilina, MIC ≥ 256µg/mL, e em 65,2% predominou a resistência constitutiva MLS Bc. Dos 20 isolados sensíveis a clindamicina, 12 apresentaram fenótipo MLS B induzível. Um total de 71,4% dos MRCoNS apresentaram resistência a eritromicina, ciprofloxacina e gentamicina. Dos isolados positivos para a enzima β-lactamases, as MIC tiveram breakpoint entre 0,5 a 2µg/mL. CONCLUSÕES: Os resultados sinalizam elevada ocorrência de bactérias multirresistentes em úlceras venosas de pacientes recebendo atenção primária, evidenciando a necessidade de medidas preventivas que evitem surtos causados por patógenos resistentes a múltiplas drogas e a importância dos profissionais em discernir infecção de colonização em úlcera venosa, critério fundamental na indicação antibioticoterapia sistêmica.

Identification of Staphylococcus spp. isolated during the ripening process of a traditional minas cheese / Identificação de Staphylococcus spp. isolados durante o processo de maturação de um queijo-de-minas tradicional

The population dynamics of Staphylococcus spp. was studied during the ripening of Canastra Minas cheese at three farms located in the State of Minas Gerais, Brazil. The presence of coagulase (coa), thermonuclease (nuc), and enterotoxin (sea, seb, sec, and sed) genes was investigated in Staphylococcus strains isolated during the 60-day cheese-ripening period. The presence of the staphylococcal enterotoxins A, C, and D was also investigated in the cheese samples. Cheese samples that were matured for 0, 7, 15, 30, and 45 days presented staphylococci counts from 10³ to 10(8)cfu/g. All isolates considered coagulase-positive by physiological tests had the coa gene. However, no association was observed between the results obtained with biochemical tests and those obtained by PCR using gene-specific primers for coagulase-negative strains. Coagulase and thermonuclease genes occurred simultaneously in 41.3 percent of Staphylococcus spp. tested. None of the investigated Staphylococcus strains expressed enterotoxins SEA, SEB, SEC, and SED. Enterotoxins A, C, and D were not detected in any of the cheese samples.

Estudou-se a dinâmica das populações de Staphylococcus spp. durante a maturação do queijo Canastra, em três fazendas localizadas no estado de Minas Gerais. A presença dos genes que codificam para a produção das enzimas coagulase (coa), termonuclease (nuc) e produção de enterotoxinas (sea, seb, sec e sed), em linhagens de Staphylococcus isoladas durante os 60 dias de maturação do queijo foi analisada. Também foi investigada a presença de enterotoxina estafilocócica A, C e D nas amostras de queijo. As amostras de queijo com 0, 7, 15, 30 e 45 dias de maturação apresentaram contagens de Staphylococcus spp. entre 10³ e 10(8)ufc / g. Todos os isolados coagulase positivo nos testes fisiológicos apresentaram o gene coa. Não foi observada associação entre os resultados obtidos com os testes bioquímicos e aqueles obtidos com a PCR usando iniciadores gene-específicos para linhagens coagulase negativa. Os genes da coagulase e termonuclease ocorreram simultaneamente em 41,3 por cento dos Staphylococcus spp. testados. Nenhum dos isolados de Staphylococcus apresentou os genes que codificam para a produção das enterotoxinas SEA, SEB, SEC ou SED. As enterotoxinas A, C ou D não foram detectadas em nenhuma das amostras de queijo analisadas.

Sepsis due to linezolid resistant Staphylococcus cohnii and Staphylococcus kloosii: First reports of linezolid resistance in coagulase negative staphylococci from India.

Linezolid, a viable alternative to vancomycin against methicillin resistant staphylococcal isolates, has been in use for a decade around the globe. However, resistance against staphylococci remains extremely rare and unreported from most of the Asian countries. Herein, we report two cases of linezolid resistant, coagulase negative staphylococcal sepsis for the first time from India. The first case was an 18-year-old burn patient, who, after a major graft surgery, landed in sepsis, and linezolid resistant Staphylococcus cohnii with an minimum inhibitory concentration (MIC) of >256 μg/ml by both broth microdilution and Etest, was isolated from multiple blood cultures. The second patient was a 60-year-old male with an intracranial bleed and sepsis, from whose blood cultures, linezolid resistant Staphylococcus kloosii was repeatedly isolated. Linezolid MIC was >32 μg/ml by broth microdilution and >16 μg/ml by Etest.

Distribution of erm genes and low prevalence of inducible resistance to clindamycin among staphylococci isolates

INTRODUCTION: Resistance to macrolides, lincosamides and streptogramins B (MLS B antibiotics) in staphylococci may be due to modification in ribosomal target methylase encoded by erm genes. The expression of MLS B resistance lead to three phenotypes, namely constitutive resistance (cMLS B), inducible resistance (iMLS B), and resistance only to macrolides and streptogramins B (MS B). The iMLS B resistance is the most difficult to detect in the clinical laboratory. OBJECTIVE: This study investigated the expression of MLS B resistance and the prevalence of the erm genes among 152 clinical isolates of Staphylococcus aureus and coagulase-negative Staphylococcus (CNS) from Hospital de Clínicas de Porto Alegre. METHODS: Primary MLS B resistance was detected by the disk diffusion method. Isolates with iMLS B phenotype were tested by double-disk induction method. All isolates were tested by a genotypic assay, PCR with specific primers. RESULTS: A total of 46.7 percent of staphylococci were positive for cMLS B; 3.3 percent for iMLS B and 3.3 percent for MS B. One or more erm genes were present in 50.1 percent of isolates. The gene ermA was detected in 49 isolates, ermC in 29 and ermB in 3. CONCLUSION: The prevalence of the ermA, ermB and ermC genes were 29.6 percent, 17.1 percent and 0.66 percent respectively, and constitutive resistance was the most frequent as compared to the other two phenotypes.

Coagulase-Positive Staphylococcal Necrotizing Fasciitis Subsequent to Shoulder Sprain in a Healthy Woman

Necrotizing fasciitis (NF) is a deep infection of the subcutaneous tissue that progressively destroys fascia and fat; it is associated with systemic toxicity, a fulminant course, and high mortality. NF most frequently develops from trauma that compromises skin integrity, and is more common in patients with predisposing medical conditions such as diabetes mellitus, atherosclerosis, alcoholism, renal disease, liver disease, immunosuppression, malignancy, or corticosteroid use. Most often, NF is caused by polymicrobial pathogens including aerobic and anaerobic bacteria. NF caused by Staphylococcus aureus as a single pathogen, however, is rare. Here we report a case of NF that developed in a healthy woman after an isolated shoulder sprain that occurred without breaking a skin barrier, and was caused by Staphylococcus aureus as a single pathogen.

Microbiota conjuntival e resistência a antibióticos em recém-nascidos prematuros internados em unidade de terapia intensiva / Conjunctival microbiota and antibiotics resistance in preterm newborns hospitalized in neonatal intensive care unit

OBJETIVO: Analisar a flora bacteriana da conjuntiva e o padrão de resistência a antibióticos em crianças recém-nascidas prematuras na Unidade de Terapia Intensiva Neonatal (UTIN) do Hospital das Clínicas da Universidade Federal de Pernambuco (UFPE). MÉTODOS: Foram analisadas amostras de secreção conjuntival de 48 recém-nascidos com permanência de pelo menos 48 horas na UTIN. RESULTADOS: Das 48 amostras 40 (83,3 por cento) apresentaram cultura positiva, com maior frequência de Staphyloccocus coagulase-negativo (43,2 por cento) e Staphyloccocus aureus (25,0 por cento). Foram consideradas multirresistentes 63,9 por cento das bactérias. Os antibióticos com maior sensibilidade no antibiograma foram gatifloxacino (97,2 por cento), vancomicina (94,4 por cento) e ofloxacino (94,4 por cento). CONCLUSÕES: A flora bacteriana da conjuntiva de prematuros na UTIN é diversificada, predominando as bactérias Gram-positivas, geralmente multirresistente a antibióticos.

PURPOSE: To analyze the conjunctival bacterial flora and the antibiotics resistance pattern in preterm newborns at the Neonatal Intensive Care Unit (NICU), in "Hospital das Clínicas da Universidade Federal de Pernambuco - UFPE". METHODS: Material from the conjunctival sac was obtained from 48 premature infants eyes that stayed at in NICU more than 48 hours. RESULTS: Culture analysis revealed that 40 (83.3 percent) were positive and the pathogens most commonly isolated included Coagulase-negative Staphylococcus (43.2 percent) and Staphylococcus aureus (25.0 percent), being 63.9 percent of the bacteria multiresistant. Antimicrobial test results demonstrated great sensitivity to gatifloxacin (97.2 percent), vancomycin (94.4 percent) and ofloxacin (94.4 percent). CONCLUSIONS: Conjunctival bacterial flora among newborns in NICU is varied, mainly Gram-positive, usually multiresistant to antibiotics.

Two outbreaks of mixed etiology associated with central venous catheters inserted by phlebotomy in critical neonates

Staphylococcus aureus and coagulase-negative staphylococci are the main cause of sepsis in Neonatal Intensive Care Unit (NICU). Central venous catheters (CVCs) are an important part of critical neonates' treatment and are associated with sepsis. The aim of this study was to investigate two outbreaks caused by Staphylococcus aureus and Staphylococcus epidermidis associated with CVC inserted by phlebotomy in critical neonates. The surveillance was performed from January 2001 to December 2005 at the Brazilian NICU. The genotypic analysis of oxacillin susceptible S. aureus (OSSA) and oxacillin resistant S. epidermidis (ORSE) was performed based on pulsed-field gel electrophoresis (PFGE). Staphylococcus was the most frequent pathogen (65.8 percent) with highest incidence of CoNS (59.9 percent) followed by S. aureus (40.1 percent). During the five years of surveillance, there were two outbreaks detected, occurred in January-February/02 and August/02 and confirmed by PFGE analysis. The predisposing factors for infection corresponding to both outbreaks were: age <7 days, hospitalization > 7 days, and use of polyethylene CVC through dissection of vein (phlebotomy). This is the first relate of staphylococcal outbreaks associated with CVC inserted by phlebotomy in NICU. PFGE showed polyclonal spread of OSSA during both epidemic and endemic period, and two monoclonal outbreaks of ORSE in the same epidemic period of OSSA.

Prevalence of staphylococcus aureus and it's toxins in street marketing milk and some milk products

In this study, the bacteriological examination of 130 street marketing milk samples and 251 milk product samples revealed that 47 isolates of Staphylococcus aureus were recovered from 130 milk samples with a percentage of 36% and 31 isolates of S.aureus were recovered from 251 milk product samples with a percentage of 12.4%. The pathogenic activity of the isolated S.aureus from milk and milk products were studied including Heamolytic activity, DNase activity and coagulase activity. The results proved that 70 isolates out of 78 tested isolates were Heamolytic and 72 isolates have DNase activity and 60 isolates have coagulase activity. By using latex slide agglutination Test was used for detection of Protein A in isolated S.aureus from milk samples. The results proved that 46 out of 47 isolates contained protein A. Concerning the ice cream samples 11 out of 13 tested isolates contained protein A. and 16 out of 18 tested isolates from Kariesh cheese contained protein A. The results showed that, out of 78 tested isolates 20 isolates were proved to be enterotoxin A producer, 2 isolates were enterotoxin B producer and 5 isolates were enterotoxin C producer by using ELISA

Study of virulence factors in coagulase-negative staphylococci isolated from newborns

Coagulase-negative staphylococci (CNS) have been identified as the etiological agent in various infections and are currently the microorganisms most frequently isolated in nosocomial infections. However, little is known about the virulence factors produced by CNS that contribute to the pathogenesis of infections caused by these microorganisms. The study of CNS isolated from infectious processes of newborns hospitalized in the Neonatal Unit of the Hospital of the Botucatu Medical School, Unesp, indicated Staphylococcus epidermidis as the most frequently isolated species (77.8 percent), which was also associated with clinically significant situations. The analysis of virulence factors revealed the production of slime in 20 (17.1 percent) of all CNS samples isolated and the synthesis of a broad spectrum of enzymes and toxins, including hemolysins (19.6 percent), lipase (17.1 percent), lecithinase (3.4 percent), DNAse (15.4 percent), thermonuclease (7.7 percent), and enterotoxin A, B or C (37.6 percent). Taking into consideration that the etiological importance of CNS has often been neglected, the present investigation confirmed that these microorganisms should not be ignored or classified as mere contaminants.

Automated systems in the identification and determination of methicillin resistance among coagulase negative staphylococci

Coagulase-negative staphylococci (CoNS) are an important cause of nosocomial bacteremia, specially in patients with indwelling devices or those submitted to invasive medical procedures. The identification of species and the accurate and rapid detection of methicillin resistance are directly dependent on the quality of the identification and susceptibility tests used, either manual or automated. The objective of this study was to evaluate the accuracy of two automated systems MicroScan and Vitek - in the identification of CoNS species and determination of susceptibility to methicillin, considering as gold standard the biochemical tests and the characterization of the mecA gene by polymerase chain reaction, respectively. MicroScan presented better results in the identification of CoNS species (accuracy of 96.8 vs 78.8 percent, respectively); isolates from the following species had no precise identification: Staphylococcus haemolyticus, S. simulans, and S. capitis. Both systems were similar in the characterization of methicillin resistance. The higher discrepancies for gene mec detection were observed among species other than S. epidermidis (S. hominis, S. saprophyticus, S. sciuri, S. haemolyticus, S. warneri, S. cohnii), and those with borderline MICs.

Ventriculoperitoneal shunt infections.

Central nervous system (CNS) shunt infection is a cause of significant morbidity, causing shunt malfunction and chronic ill health. This study was carried out to evaluate the infection rate associated with CNS shunts, assess the frequency of the pathogens as well as their antibiotic sensitivity pattern aiming at suitable prophylaxis. A retrospective analysis of 226 CSF cerebrospinal fluid (CSF) shunt procedures sent for bacteriological work up over a period of one year and six months was undertaken. Laboratory diagnosis was established by subjecting the CSF to cell count, biochemical tests, bacteriological culture and antibiotic susceptibility test. Nine out of 226(3.98%) of the CSF samples were culture positive. Coagulase negative Staphylococcus was the most common isolate accounting for 36.36%. Majority of the isolates were sensitive to the thirdgeneration cephalosporins and quinolones. The antibiotic sensitivity pattern suggests cephalosporins and quinolones to be a better choice of antibiotics either prophylactically or therapeutically, which may result in effective and rapid sterilisation of the CSF.

Significance of coagulase negative staphylococci in neonates with late onset septicemia.

Present study was undertaken for establishing significance of coagulase negative staphylococci isolated from cases of late onset neonatal septicemia. 660 neonates admitted to NICU with clinical suspicion of late onset septicemia, over a period of nine months, were included in study. After skin preparation 1.5-ml blood for culture was collected from two different sites by venipuncture and each was inoculated into a blood culture bottle. All CONS thus isolated were further analysed. Laboratory criteria for significant CONS bacteremia was defined as recovery of CONS with in 48 hours of specimen collection from both sites of a blood culture set that displayed uniform antibiotic susceptibility and biochemical reactions. Due to technical difficulties two samples for blood culture were obtained only from 338 cases, CONS were recovered from 52 (22.7%) cases; only 13 (25%) were considered significant. Only single blood sample was available from remaining 322 subjects and CONS were recovered from 36/322 (24.3%). CONS isolation rate was similar in both subject groups. Using double specimen protocol we found majority of CONS recovered from neonates, to be probable contaminants. Recovery of CONS from blood of a septicemic neonate needs to be viewed with caution since not all of them are true bacteremic agents.

Detection of slime production by coagulase-negative Staphylococcus: an assessment of two methods.

The detection of slime can be helpful in determining the diagnostic value of coagulase-negative Staphylococcus (CNS). Here, we have made a comparative study of two phenotypic methods of slime production test from 28 clinically significant blood culture isolates of CNS. A total 16 out of 28 isolates (57.1%) were positive for slime by either of the tests, whereas only 5 out of 28 isolates (17.9%) were positive for slime by both the tests. The tube method detected slime in significantly more number of isolates than the spectrophotometric method (14 vs. 7; p<0.0483279). A weak correlation was found between the tube method and the spectrophotometric method (rs=0.2474). The tube test was found to be superior to the spectrophotometric test in terms of sensitivity, ease of performance and interpretation, and cost effectiveness.