Coagulase-negative staphylococci in Southern Brazil: looking toward its high diversity

Abstract: INTRODUCTION: Coagulase-negative staphylococci (CoNS) are the most prevalent pathogens in nosocomial infections and may serve as a reservoir of mobile genetic elements such as the staphylococcal cassette chromosome mec (SCCmec) encoding methicillin resistance. Molecular characterization of SCCmec types combined with advanced molecular typing techniques may provide essential information for understanding the evolution and epidemiology of CoNS infections. We therefore aimed to investigate the SCCmec distribution, multidrug-resistance (MDR), and biofilm formation in CoNS blood culture isolates from a hospital in Southern Brazil. METHODS: We analyzed 136 CoNS blood culture isolates obtained during 2002-2004 from patients admitted to a tertiary care hospital in Brazil. SCCmec types I to V were determined using multiplex PCR. The clonal relationship of Staphylococcus epidermidis was determined using pulsed field gel electrophoresis (PFGE) and multilocus sequence typing (MLST). Molecular epidemiological data were interpreted along with data on biofilm formation, presence of the icaD gene, and MDR. RESULTS: The most prevalent species were S. epidermidis, Staphylococcus haemolyticus, and Staphylococcus hominis harboring mainly SCCmec types II, III, and V. Overall, the presence of multiple SCCmec was associated with non-MDR, except for S. epidermidis. S. epidermidis isolates showed a high prevalence of icaD, but had low phenotypic biofilm formation. PFGE and MLST revealed high genetic diversity in the S. epidermidis population. CONCLUSIONS: Our results suggest a major shift in SCCmec types within a short period and reveal a different behavior of S. epidermidis with regard to the association between the presence of multiple SCCmec types and MDR profile.

Correlation of beta-lactamase production/methicillin resistance and phage pattern of Staphylococcus aureus.

Multiple drug resistance is exhibited by coagulase positive staphylococcus aureus isolated from hospitals. Prevalence of MRSA due to prolonged stay in the hospital, instrumentation/invasive procedure, surgical intervention and misuse of antibiotics have been reported. Antibiogram of 200 coagulase staphylococci showed 10% MRSA strains. Predominant phage type 81 belonged to unclassified group followed by phage type 84 belonged to group 3. As the management of MRSA is not easy, efforts should be made to eradicate the MRSA by taking strict aseptic conditions and the severe infections should be treated according to the sensitivity pattern of the strain.

Resistant coagulase negative staphylococci from clinical samples.

Antibiotic susceptibility testing against 17 antibiotics was done on 96 strains of various species of coagulase negative staphylococci by Stokes method. Hundred per cent sensitivity was found against vancomycin and cefotaxime and about 90 per cent against ciprofloxacin, clavulanate potentiated amoxycillin, cloxacillin and clindamycin. Strains showed highest resistance against cotrimoxazole (77.08%) and tetracycline (64.59%). Clavulanate potentiated amoxycillin was found to be highly active against penicillin, ampicillin and amoxycillin resistant organisms. The results highlight the importance of antibiotic resistance typing among coagulase negative staphylococci species which are increasingly being reported from serious clinical infections making empiric therapy and selection of antibiotics difficult in these infections.

Evaluation of topical povidone-iodine versus gentamycin in staphylococcus coagulase positive corneal ulcers--an experimental study.

Povidone iodine was found highly effective in controlling the infection and reducing the period of morbidity caused by experimentally produced staphylococcal coagulase positive corneal ulcers in 50 eyes of rabbits in comparison to Gentamycin sulphate. Povidone-iodine was also found to be safe, without any adverse reaction. Hence it can be considered for use in human beings for effective control of corneal infections.

Efeito do íon ferro e da conalbumina no desenvolvimento e produçäo de proteínas extracelulares na linhagem Staphylococcus aureus S-6 / Effect of iron and conalbumin on the development and production of extracellular proteins by Staphylococcus aureus S-6 strain

O efeito da concentraçäo do íon ferro assim como da proteína conalbumina foi estudado na linhagem Staphylococcus aureus S-6 desenvolvida num meio contendo hidrolizado de caseína, meio NAK, e no mesmo após a remoçäo dos íons, meio NAKSA. Outras propriedades estudadas foram a produçäo de proteínas extracelulares coagulase, nuclease e as enterotoxinas A (EEA) e B (EEB). A adiçäo de ferro em concentraçöes superiores a 1,19microng/ml ao meio NAKSA contendo 1,11microng/ml de Mg2+ teve como consequência efeitos adversos, tanto para o desenvolvimento do microrganismo, quanto na produçäo de DNAse e EEB. A adiçäo de conalbumina ao meio NAKSA com 1,11microng/ml de Mg2+ näo teve efeito inibitório nas propriedades estudadas, ocorrendo inclusive um ligeiro estímulo na produçäo de proteínas extracelulares. A adiçäo de ferro näo afetou a retençäo de DNAse ligada à superfície celular, indicando que a açäo inibitória foi a nível de produçäo e näo de liberaçäo da enzima