Characteristics of Archived Coagulase Negative <i>Staphylococci</i>Isolates at a University Hospital, Nairobi, Kenya

Background: Coagulase negative Staphylococci (CoNS) are normal inhabitants of the skin and mucous membranes and thus have been dismissed for a long time as culture contaminants even if they have been isolated from sterile specimens. The risk factors for CoNS infections include patients who are immunocompromised, implanted with foreign bodies or with indwelling devices. The aim of this study was to determine the antimicrobial susceptibility patterns and presence of mecA gene in methicillin resistant CoNS isolated in a teaching and referral hospital in Kenya. Methodology: This was a cross sectional retrospective study. Archived isolates were sub-cultured on 5% sheep blood agar. Speciation and antimicrobial susceptibility patterns were performed by Vitek2 technique. The presence of mecA gene was determined by (PCR). Results: A total of seven species were identified with Staphylococcus epidermidis having the highest percentage at 45.4% and Staphylococcus warneri with the lowest at 2.6%. High resistance to antibiotics that were tested was observed regardless of the source of the isolate. MecA gene was found in 90% of the isolates. Conclusion: Coagulase negative Staphylococci exhibited high levels of resistance generally. Most of the isolates carried the mecA gene. Despite some of the isolates being resistant to Cefoxitin, the mecA gene was not found. There is a possibility that methicillin resistance in these isolates is mediated using a different mechanism.

Diversity and Distribution of Staphylococcal Chromosomal Cassettes Mec (SCCmec) Types I, II and III in Coagulase-Negative Staphylococcal Strains Isolated from Surfaces and Medico-Technical Materials of the University Hospital of Abomey-Calavi/Sô-Ava

The coagulase-negative staphylococci (CoNS) have long been considered to be low pathogenicity. The possibility of a horizontal transfer of resistance and virulence genes from S. aureus to CoNS could increase the pathogenicity of these bacteria. The objective of this work is to contribute to a better knowledge of the pathogenicity of (CoNS) strains isolated from surfaces and medico-technical materials of the University Hospital of Abomey-Calavi/Sô-Ava. Seventy strains of CoNS isolated from surfaces and medico-technical materials of the University Hospital of Abomey-Calavi were tested for methicillin resistance. The resistance to methicillin was evaluated phenotypically by the resistance of the strains to cefoxitin and then confirmed by the search for the mecA gene using PCR. The genes encoding staphylococcal chromosomal cassette (SCCmec) types I, II and III originally found in S. aureus were tested in CoNS by multiplex PCR using specific primers. All the strains studied showed resistance to methicillin. However, only 28.5% (20/70) carried the mecA gene. SCCmec was identified in only 17.14% (12/70) of these strains. Four strains carried mecA gene as well as one of the three types of SCCmec searched. SCCmec types I, II and III were identified in CoNS strains studied. SCCmec type I was the most frequent chromosomal cassette in mecA+ strains, only or in association with another SCCmec. The study also revealed methicillin-resistant strains carrying SCCmec lacking the mecA gene. Finally, 60% (12/20) of the strains were found to be non-typeable. Our results show that CoNS strains present a high resistance to methicillin and the source of this resistance in the CoNS of our study is not only the mecA gene. There is also a high diversity of SCCmec, justified by a large number of non-typeable CoNS strains. The mecA− SCCmec+ methicillin-resistant strains deserve to be sequenced for further studies.

Determination of antimicrobial resistance profile and inducible clindamycin resistance of coagulase negative staphylococci in pediatric patients: the first report from Iran

Background:Currently,coagulase negative staphylococci(CoNS)have got much attention as a serious health problem especially in neonates and children.High incidence of antibiotic resistance,in particular methicillin resistance,has complicated the treatment of these organisms.The aim of this study is to determine the susceptibility to different antimicrobial agents and the prevalence of macrolides-lincosamides-streptogramins B(MLS_(B))resistance in CoNS isolates obtained from pediatric patients.Methods:Totally 157 CoNS isolates from various clinical samples were examined for antibiotic resistance using disk diffusion and E-test methods.Double-disk test was applied to detect constitutive and inducible MLSB resistance(cMLS_(B)and iMLS_(B))phenotypes.Results:Resistance to methicillin was seen in 98(62.4%)isolates.All isolates were susceptible to vancomycin and linezolid.The prevalence of resistance to antibiotics tested was as follows:fusidic acid(n=58,36.9%),gentamicin(n=73,46.5%),ciprofloxacin(n=81,51.6%),clindamycin(n=112,71.3%),erythromycin(n=129,82.2%)and trimethoprim/sulfamethoxazole(n=133,84.7%).iMLS_(B)phenotype was seen in 14(8.9%)isolates,and 18(11.5%)and 98(62.4%)isolates showed MS and cMLS_(B)phenotypes,respectively.We observed that high overall antibiotic resistance rates were associated significantly with methicillin resistance.Conversely,iMLS_(B)phenotype was correlated neither with methicillin resistance nor with invasiveness.Conclusion:Given the similarity observed between the prevalence of iMLS_(B)and MS phenotypes,the performance of disk diffusion induction test is strongly recommended in our region.

医院感染血浆凝固酶阴性葡萄球菌耐药性分析

目的 了解医院感染血浆凝固酶阴性葡萄球菌 (coagulasenegativestaphylococciCONS) β -内酰胺酶 ,粘质物产生等耐药性的情况。方法 对临床分离CONS予以鉴定 ,琼脂纸片扩散法 (K -B)检测药敏 ,Ni trocefin法检测 β -内酰胺酶 ,刚果红平板法检测粘质物。 结果 临床分离CONS对青霉素、红霉素、复方新诺明、苯唑西林、环丙沙星、克林霉素的耐药率较高 ,分别为 85 .4 %、81.0 %、79.8%、6 7.7%、5 8.2 %和5 5 .1% ,对氨苄西林 /舒巴坦、利复平、美洛培南较敏感 ,耐药率分别为 8.9%、17.1%和 2 4 .7% ,未发现有耐万古霉素的菌株。β -内酰胺酶阳性率为 72 .8% ,粘质物阳性率为 8.9%。 结论 CONS耐药性增高与其产β -内酰胺酶、粘质物有关 ,同时还会导致耐甲氧西林凝固酶阴性葡萄球菌 (methicillin -resistantcoagulasenega tive,staphylococciMRCONS)出现。

Identification of Microbes in Patients with Lumbar Disc Herniation

Apart from the conventional factors, recent evidences have suggested that lumbar disc herniation (LDH) is also associated with microbes, which is completely ignored in the management of patients with disc prolapse and disc degeneration. Therefore, the present study was carried out to identify the different microorganisms in subjects with LDH. Subjects (n = 101) who were confirmed for LDH with Magnetic Resonance Imaging and undergoing lumbar discectomy, were recruited in this study. Standard protocols for disinfection of the skin and surgical instruments were adhered. Skin scrapings, muscle biopsies and portion of the inter-vertebral disc were transferred into individually labeled Robertson’s cooked meat enrichment broth for anaerobic identification. Remaining portions of the excised disc material and muscle biopsy were taken for aerobic identification. Anaerobic isolates were identified using Gram stain and catalase test while the species identification was done by RapID ANA II ID kit. Gram stain, catalase test, DNase test and coagulase tests were used for identification of aerobic bacteria. Study confirmed 6/101 disc cultures (6%) with positive anaerobes and 12 disc cultures with coagulase negative Staphylococci spp. Among the anaerobes, two disc cultures were identified as Propionibacterium acnes and one as Gemella morbillorum. Due to slow growth, other three anaerobic cultures were not confirmed. However, they resembled the colony morphology of Gram positive bacilli. None of the control samples (skin and muscles) had any positive growth. The present study adds to the literature confirming the role of microorganisms in LDH. Present study newly identified Gemella morbillorum in the intervertebral tissue in addition to the previously reported microorganisms associated with LDH.

Staphylococcus cohnii: Not so innocuous

Staphylococcus cohnii is not known to causes meningitis. We present a case of mennigitis due to this organism. We are highlighting this case not only for its rarity but rapidity of worsening also. This report indicates that Staphylococcus cohnii are not as innocuous as once thought to be and these organisms should not be disregarded as possible skin contaminants. Before labelling them as contaminants their possible association with disease should be ruled out.

凝固酶阴性葡萄球菌超氧化物歧化酶基因研究

目的研究凝固酶阴性的葡萄球菌(CoNS)超氧化物歧化酶(sodA)基因在不同菌种中的表达,寻找相关的特异基因序列。方法对116株CoNS标本进行菌种鉴定,采用聚合酶链反应进行sodA基因及icaD基因片段扩增,选取有代表性的菌株经克隆后测序并进行分析。结果CoNS的DNA序列分析未发现与致病性相关的序列差异。结论sodA基因不适合作为致病性与非致病性CoNS鉴别的生物标记,但可以作为鉴定CoNS的一个基因标记。