Molecular evidence of person-to-person transmission of a pigmented strain of Corynebacterium striatum in intensive care units

Metagenomic next-generation sequencing for the diagnosis of Corynebacterium striatum meningitis: case report and literature review

OBJECTIVE

To report a case of Corynebacterium striatum meningitis and conduct a comprehensive literature review to determine the clinical presentation, microbiology, and treatment approaches for these patients.

MATERIALS AND METHODS

A 75-year-old male patient presented with headache and fever; however, bacterial cultures of cerebrospinal fluid (CSF) yielded negative results. Metagenomic next-generation sequencing (mNGS) of CSF subsequently identified Corynebacterium striatum meningitis as the causative agent for meningitis. A systematic search was performed across various databases encompassing systematic reviews, cohort studies, case series, and case reports involving patients diagnosed with Corynebacterium striatum meningitis regardless of age. Clinical presentation characteristics and the most frequently employed diagnostic technologies were obtained. A narrative summary of the findings is presented.

RESULTS

Corynebacterium striatum meningitis patients do not exhibit any specific age or sex predisposition or distinctive symptoms or signs. In patients with Corynebacterium striatum meningitis, CSF tests typically reveal an increased number of white blood cells (predominantly polymorphonuclear cells), elevated protein levels, and decreased glucose levels. Notably, the prevalence of antibiotic-resistant strains of Corynebacterium striatum has increased in recent years, leading to a gradual rise in antibiotic treatment failure rates. It is predicted that by 2030, vancomycin may be the sole effective drug available.

CONCLUSION

The possibility of Corynebacterium striatum infection should be considered during clinical diagnosis and laboratory testing procedures for bacterial meningitis. mNGS can serve as a supplementary gold standard in the diagnosis of bacterial meningitis, effectively enhancing the detection rate of rare pathogens.

Comparison of bloodstream infections due to Corynebacterium striatum, MRSA, and MRSE

BACKGROUND

Corynebacterium striatum (C. striatum), a common skin and mucosal colonizer, is increasingly considered as an opportunistic pathogen causing bloodstream infections (BSIs). This study aims to investigate the clinical features and outcomes of C. striatum-BSI.

METHODS

We included hospitalized cases with C. striatum-positive blood cultures from January 2014 to June 2022 and classified them into C. striatum-BSI group and contamination group; Clinical characteristics, treatments, and outcomes were compared between the C. striatum-BSI group and contamination group, Methicillin-resistant Staphylococcus aureus (MRSA)-BSI and Methicillin-resistant Staphylococcus epidermidis (MRSE)-BSI.

RESULTS

Fifty-three patients with positive C. striatum blood cultures were identified. Among them, 25 patients were classified as C. striatum-BSI, with 21 as contamination cases. And 62 cases of MRSA-BSI and 44 cases of MRSE-BSI were identified. Compared to the contaminated group, the C. striatum-BSI group had a shorter time to positivity of blood cultures (27.0 h vs. 42.5 h, P = 0.011). C. striatum-BSI group had a longer time to positivity (27 h) when compared to both the MRSA (20 h) and MRSE groups (19 h) (p < 0.05). Appropriate therapy within 24 h of BSI onset was significantly lower in the C. striatum group (28%) compared to the MRSA (64.5%) and MRSE (65.9%) groups (p < 0.005). The 28-day mortality was higher in the C. striatum group (52.0%) compared to the MRSA (25.8%) and MRSE (18.2%) groups.  CONCLUSIONS: Given the distinct characteristics of C. striatum-BSI, including a longer time to positivity than other Gram-positive bacteria and higher mortality rates, we suggest prescribing early appropriate antibiotics if C. striatum-BSI is suspected.

Hard-to-heal peripheral wounds infected with Corynebacterium striatum: a prospective study

OBJECTIVE

To investigate Corynebacterium striatum as a nosocomial pathogen infecting hard-to-heal peripheral wounds, such as skin wounds, soft tissue abscesses and osteomyelitis. As of 2023, the medical community were alerted against the risk of emerging systemic and central infections; on the other hand literature on peripheral cutaneous regions is still scarce.

METHOD

In this study, two groups of patients with similar lesions which were infected were compared: one group with the presence of the coryneform rod, the other without.

RESULTS

In total, Corynebacterium striatum was cultured from 62 patients and 131 samples. Corynebacterium striatum infection correlated well with the presence of: foot ulcer; venous leg ulcer; altered ambulation and/or altered foot loading; peripheral vascular and arterial disease; hospitalisation; malignancy; spinal cord injury; and recent administration of antibiotics (p<0.05 for all associations). Patients with Corynebacterium striatum had a lower overall survival rate compared to patients in the non-Corynebacterium striatum group (28.6 versus 31.6 months, respectively; p=0.0285). Multivariate analysis revealed that Corynebacterium striatum infection was an independent factor for poor prognosis (p<0.0001).

CONCLUSION

In view of the findings of our study, Corynebacterium striatum appears to be an important opportunistic pathogen infecting peripheral tissues and complicating wound healing. Given its numerous and worrying virulence factors (such as multidrug resistance and biofilm production), particular attention should be given to this pathogen by professional wound care providers in nosocomial and outpatient environments.

Involvement of the genus Corynebacterium in the pathogenesis of pigmented intratarsal keratinous cyst

Intratarsal keratinous cyst (IKC) is a benign cystic lesion of the eyelid that retains keratin flakes. IKCs are usually yellow to white cystic lesions but rarely become brown or gray-blue, making clinical diagnosis difficult. The mechanisms by which dark brown pigments are generated in pigmented IKC are unclear. The authors report a case of pigmented IKC that had melanin pigments within the lining of the cyst wall and within the cyst. Focal infiltrates of lymphocytes were observed in the dermis, particularly beneath the cyst wall in areas with more melanocytes and intense melanin deposition. These pigmented parts faced bacterial colonies inside the cyst, which were identified to be Corynebacterium species in a bacterial flora analysis. The pathogenesis of pigmented IKC in relation to inflammation and bacterial flora is discussed.

Epidemiological Investigation of Hospital Transmission of Corynebacterium striatum Infection by Core Genome Multilocus Sequence Typing Approach

Corynebacterium striatum has recently received increasing attention due to its multiple antimicrobial resistances and its role as an invasive infection/outbreak agent. Recently, whole-genome sequencing (WGS)-based core genome multilocus sequence typing (cgMLST) has been used in epidemiological studies of specific human pathogens. However, this method has not been reported in studies of C. striatum. In this work, we aim to propose a cgMLST scheme for C. striatum. All publicly available C. striatum genomes, 30 C. striatum strains isolated from the same hospital, and 1 epidemiologically unrelated outgroup C. striatum strain were used to establish a cgMLST scheme targeting 1,795 genes (hereinafter referred to as 1,795-cgMLST). The genotyping results of cgMLST showed good congruence with core genome-based single-nucleotide polymorphism typing in terms of tree topology. In addition, the cgMLST provided a greater discrimination than the MLST method based on 6 housekeeping genes (gyrA, gyrB, hsp65, rpoB, secA1, and sodA). We established a clonal group (CG) threshold based on 104 allelic differences; a total of 56 CGs were identified from among 263 C. striatum strains. We also defined an outbreak threshold based on seven allelic differences that is capable of identifying closely related isolates that could give clues on hospital transmission. According to the results of analysis of drug-resistant genes and virulence genes, we identified CG4, CG5, CG26, CG28, and CG55 as potentially hypervirulent and multidrug-resistant CGs of C. striatum. This study provides valuable genomic epidemiological data on the diversity, resistance, and virulence profiles of this potentially pathogenic microorganism. IMPORTANCE Recently, WGS of many human and animal pathogens has been successfully used to investigate microbial outbreaks. The cgMLST schema are powerful genotyping tools that can be used to investigate potential epidemics and provide classification of the strains precise and reliable. In this study, we proposed the development of a cgMLST typing scheme for C. striatum, and then we evaluated this scheme for its applicability to hospital transmission investigations. This report describes the first cgMLST schema for C. striatum. The analysis of hospital transmission of C. striatum based on cgMLST methods has important clinical epidemiological significance for improving nosocomial infection monitoring of C. striatum and in-depth understanding of its nosocomial transmission routes.

Wide spread and diversity of mutation in the gyrA gene of quinolone-resistant Corynebacterium striatum strains isolated from three tertiary hospitals in China

BACKGROUND

Corynebacterium striatum was confirmed to be an important opportunistic pathogen, which could lead to multiple-site infections and presented high prevalence of multidrug resistance, particularly to quinolone antibiotics. This study aimed to investigate the mechanism underlying resistance to quinolones and the epidemiological features of 410 quinolone-resistant C. striatum clinical strains isolated from three tertiary hospitals in China.

METHODS

A total of 410 C. striatum clinical strains were isolated from different clinical samples of patients admitted to three tertiary teaching hospitals in China. Antibiotic susceptibility testing was performed using the microdilution broth method and pulsed-field gel electrophoresis (PFGE) was used for genotyping. Gene sequencing was used to identify possible mutations in the quinolone resistance-determining regions (QRDRs) of gyrA.

RESULTS

In total, 410 C. striatum isolates were sensitive to vancomycin, linezolid, and daptomycin but resistant to ciprofloxacin. Depending on the antibiotic susceptibility testing results of 12 antimicrobial agents, the 410 C. striatum strains were classified into 12 resistant biotypes; of these, the three biotypes R1, R2, and R3 were dominant and accounted for 47.3% (194/410), 21.0% (86/410), and 23.2% (95/410) of the resistant biotypes, respectively. Mutations in the QRDRs ofgyrA were detected in all quinolone-resistant C. striatum isolates, and 97.3% of the isolates (399/410) showed double mutations in codons 87 and 91 of the QRDRs of gyrA. Ser-87 to Phe-87 and Asp-91 to Ala-91 double mutation in C. striatum was the most prevalent and accounted for 72.2% (296/410) of all mutations. Four new mutations in gyrA were identified in this study; these included Ser-87 to Tyr-87 and Asp-91 to Ala-91 (double mutation, 101 isolates); Ser-87 to Val-87 and Asp-91 toGly-91 (double mutation, one isolate); Ser-87 to Val-87 and Asp-91 to Ala-91 (double mutation, one isolate); and Ser-87 to Ile-87 (single mutation, one isolate). The minimum inhibitory concentration of ciprofloxacin for isolates with double (96.5%; 385/399) and single (72.7%; 8/11) mutations was high (≥ 32 µg/mL). Based on the PFGE typing results, 101 randomly selected C. striatum strains were classified into 50 genotypes (T01-T50), including the three multidrug-resistant epidemic clones T02, T06, and T28; these accounted for 14.9% (15/101), 5.9% (6/101), and 11.9% (12/101) of all genotypes, respectively. The multidrug-resistant T02 clone was identified in hospitals A and C and persisted from 2016 to 2018. Three outbreaks resulting from the T02, T06, and T28 clones were observed among intensive care unit (ICU) patients in hospital C between April and May 2019.

CONCLUSIONS

Quinolone-resistant C. striatum isolates showed a high prevalence of multidrug resistance. Point mutations in the QRDRs of gyrA conferred quinolone resistance to C. striatum, and several mutations in gyrA were newly found in this study. The great clonal diversity, high-level quinolone resistance and increased prevalence among patients susceptible to C. striatum isolates deserve more attention in the future. Moreover, more thorough investigation of the relationship between quinolone exposure and resistance evolution in C. striatum is necessary.

Treat Me Well or Will Resist: Uptake of Mobile Genetic Elements Determine the Resistome of Corynebacterium striatum

Corynebacterium striatum, a bacterium that is part of the normal skin microbiota, is also an opportunistic pathogen. In recent years, reports of infections and in-hospital and nosocomial outbreaks caused by antimicrobial multidrug-resistant C. striatum strains have been increasing worldwide. However, there are no studies about the genomic determinants related to antimicrobial resistance in C. striatum. This review updates global information related to antimicrobial resistance found in C. striatum and highlights the essential genomic aspects in its persistence and dissemination. The resistome of C. striatum comprises chromosomal and acquired elements. Resistance to fluoroquinolones and daptomycin are due to mutations in chromosomal genes. Conversely, resistance to macrolides, tetracyclines, phenicols, beta-lactams, and aminoglycosides are associated with mobile genomic elements such as plasmids and transposons. The presence and diversity of insertion sequences suggest an essential role in the expression of antimicrobial resistance genes (ARGs) in genomic rearrangements and their potential to transfer these elements to other pathogens. The present study underlines that the resistome of C. striatum is dynamic; it is in evident expansion and could be acting as a reservoir for ARGs.

Antimicrobial treatment of Corynebacterium striatum invasive infections: a systematic review

The aim of this study was to establish an evidence-based guideline for the antibiotic treatment of Corynebacterium striatum infections. Several electronic databases were systematically searched for clinical trials, observational studies or individual cases on patients of any age and gender with systemic inflammatory response syndrome, harboring C. striatum isolated from body fluids or tissues in which it is not normally present. C. striatum had to be identified as the only causative agent of the invasive infection, and its isolation from blood, body fluids or tissues had to be confirmed by one of the more advanced diagnostic methods (biochemical methods, mass spectrometry and/or gene sequencing). This systematic review included 42 studies that analyzed 85 individual cases with various invasive infections caused by C. striatum. More than one isolate of C. striatum exhibited 100% susceptibility to vancomycin, linezolid, teicoplanin, piperacillin-tazobactam, amoxicillin-clavulanate and cefuroxime. On the other hand, some strains of this bacterium showed a high degree of resistance to fluoroquinolones, to the majority majority of β-lactams, aminoglycosides, macrolides, lincosamides and cotrimoxazole. Despite the antibiotic treatment, fatal outcomes were reported in almost 20% of the patients included in this study. Gene sequencing methods should be the gold standard for the identification of C. striatum, while MALDI-TOF and the Vitek system can be used as alternative methods. Vancomycin should be used as the antibiotic of choice for the treatment of C. striatum infections, in monotherapy or in combination with piperacillin-tazobactam. Alternatively, linezolid, teicoplanin or daptomycin may be used in severe infections, while amoxicillin-clavulanate may be used to treat mild infections caused by C. striatum.

Resistance to Antiseptics and Disinfectants of Planktonic and Biofilm-Associated Forms of Corynebacterium striatum

Disinfection and antisepsis are of primary importance in controlling nosocomial infections and outbreaks by pathogens expressing multiple resistance to antimicrobial agents (multidrug-resistant [MDR]) used in therapy. Nowadays, infections related to health services (HAIs) due to MDR and multidrug-susceptible (MDS) Corynebacterium striatum should not be underestimated, including patients using invasive medical devices. The virulence potential of C. striatum needs further investigation. Currently, susceptibility profiles of planktonic and/or sessile forms of four C. striatum strains of different pulsed-field gel electrophoresis types were examined as biocides based on the manufacturer's recommendations: 2% glutaraldehyde (GA), 2% peracetic acid (PA), 1% potassium monopersulfate (Virkon^®; VK), 1% sodium hypochlorite (SH), and 70% ethyl alcohol (ET). Time-kill assays using 2% bovine serum albumin (BSA) were performed for evaluation of influence of organic matter on biocides effects. Planktonic forms expressed GA resistance at different levels. C. striatum viability was observed until 2, 4, 20, and 30 min for MDR 2369/II, MDS 1954/IV, MDR 1987/I, and MDS 1961/III strains, respectively. In contrast to GA, the biocides PA, VK24h, SH, and ET had higher effective bacterial mortality. However, storage of VK (48 hr) reduced their biocide activities. Moreover, mature biofilms were produced on abiotic substrates, including steel surfaces. Post-treatment with GA (30 min), survival of sessile forms was ≥100% than planktonic forms of all C. striatum tested strains. Independent of biocides tested, BSA increased the survival of planktonic and sessile forms (p ≤ 0.005). Present data indicated that hospital staff should be aware of dissemination and eradication of HAIs by C. striatum presenting resistance to biocides, including high-level disinfectants, such as GA.

Antimicrobial Resistance and Molecular Epidemiology of Corynebacterium striatum Isolated in a Tertiary Hospital in Turkey

Although Corynebacterium striatum is part of the human flora, it has recently drawn attention both for its multidrug resistance and its role as an invasive infection/outbreak agent. This cross-sectional study aimed to determine the antimicrobial resistance and clonal relationships among C. striatum strains. In total, 81 C. striatum strains were identified using Phoenix-100^TM (BD, Sparks, MD, USA). The antimicrobial resistance of the strains was determined using the Kirby–Bauer disk diffusion method. Clonal relatedness among the strains was performed via arbitrarily primed polymerase chain reaction (AP-PCR). All 81 C. striatum strains were resistant to penicillin, cefotaxime, ciprofloxacin, and tetracycline, but susceptible to vancomycin and linezolid. The resistance rates to gentamicin, erythromycin, and clindamycin were 34.6%, 79%, and 87.7% respectively. AP-PCR results showed no predominant clone among the C. striatum strains. Corynebacterium striatum is reportedly the cause of an increasing number of invasive infections/outbreaks. Moreover, treatment options are limited. The study showed that vancomycin, linezolid, and gentamicin can be selected for the empirical treatment of C. striatum infections. Although no single-clone outbreak was observed in our hospital, small clonal circulations were observed within some units, indicating cross-contamination. Therefore, a comprehensive infection control program is warranted in future.

Carriage of a Single Strain of Nontoxigenic Corynebacterium diphtheriae bv. Belfanti (Corynebacterium belfantii) in Four Patients with Cystic Fibrosis

Cystic fibrosis (CF) patients are commonly colonized by bacterial pathogens, which can induce persistent lung inflammation and may contribute to clinical deterioration. Colonization of CF patients and cross-transmission by Corynebacterium diphtheriae have not been reported so far. The aim of this article was to investigate the possibility of a cross-transmission of C. diphtheriae biovar Belfanti between four patients of a CF center. C. diphtheriae biovar Belfanti (now formally called C. belfantii) isolates were collected from four patients in a single CF care center over a period of 6 years and analyzed by microbiological methods and whole-genome sequencing. Epidemiological links among patients were investigated. Ten isolates were collected from 4 patients. Whole-genome sequencing of one isolate from each patient showed that a single strain was shared among them. In addition, one patient was found to have the same strain in two consecutive samplings performed 9 months apart. The strain was nontoxigenic and was susceptible to most antimicrobial agents. Ciprofloxacin resistance was observed in one patient. The idea of transmission of the strain among patients was supported by the occurrence of same-day visits to the CF center. This study demonstrated colonization of CF patients by C. diphtheriae biovar Belfanti (C. belfantii), and the data suggest persistence and transmission of a unique strain during at least 6 years in a single CF patient care center.

Molecular epidemiology and clinical significance of Corynebacterium striatum isolated from clinical specimens

Purpose

This study investigated the clinical epidemiology, antimicrobial susceptibility, and molecular epidemiology of Corynebacterium striatum isolates.

Patients and methods

An observational study was conducted at a university hospital in the Republic of Korea from August to December 2016. All subjects were patients who tested positive for C. striatum clinically. Clinical data were analyzed to evaluate the microbiological and genotypic characteristics of C. striatum strains.

Results

Sixty-seven C. striatum isolates recovered from non-duplicated patients were characterized. Patients were classified into three groups according to the infection type: nosocomial infection (71.6%), health care-associated infection (8.7%), and community-acquired infection (18.8%). The most common clinical specimens were urine (35.8%) and skin abscesses (32.8%). Fifty-two (77.6%) isolates showed multidrug resistance, defined as resistance to ≥3 different antibiotic families. All strains were susceptible to vancomycin and linezolid. Resistance to other antibiotics varied: penicillin (n=65; 97.0%), ampicillin (n=63; 94.0%), cefotaxime (n=64; 95.5%), and levofloxacin (n=61; 91.0%). Phylogenetic analysis identified all 16 S rRNA gene sequences of the 67 isolates as those of C. striatum, where 98%–99% were homologous to C. striatum ATCC 6940. In multilocus sequence typing for internal transcribed spacer region, gyrA, and rpoB sequencing, the most predominant sequence types (STs) were ST2, ST3, ST6, and ST5.

Conclusion

C. striatum isolates may cause opportunistic infections associated with nosocomial infections through horizontal transmission. The presence of multidrug resistance and intra-hospital dissemination implicate C. striatum isolates as a potential target pathogen for infection control and antimicrobial stewardship programs.

Factors affecting the clinical relevance of Corynebacterium striatum isolated from blood cultures

This study aimed to identify clinical or microbiological factors affecting the clinical relevance of Corynebacterium striatum isolated from blood cultures. A total of 64 isolates from 51 patients identified as C. striatum by matrix assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) and 16S rRNA gene sequencing were assessed. More than two blood cultures were positive in 25 (48.1%) patients. Diabetes, solid tumor, and a history of previous exposure to antibiotics were more common in patients with multiple positive blood cultures. Charlson comorbidity scores were also higher, and more isolates were recovered after 48 hours of hospital stay in patients with multiple positive blood cultures. Strains recovered from patients with multiple positive blood cultures produced significantly more biofilm. Based on multilocus sequence typing (MLST), sequence type (ST) 20 (31.3%) was the most dominant, followed by ST2 (20.3%) and ST23 (10.9%). There was no relationship between the number of positive blood culture sets and sequence typing. In multivariate analyses, Carlson comorbidity score (odds ratio [OR], 1.91; 95% confidence interval [CI], 1.09–3.36; P = 0.03) and biofilm formation were associated with multiple positive blood cultures (OR, 17.43; 95% CI, 3.71–81.91; P = 0.03). This study provides evidence that the biofilm phenotype could contribute to determining the clinical significance of C. striatum in patients with severe underlying conditions. The predominance of certain STs suggests the relatedness of C. striatum infection and the nosocomial environment.

Comparison between disk diffusion and agar dilution methods to determine in vitro susceptibility of Corynebacterium spp. clinical isolates and update of their susceptibility

OBJECTIVES

Although Corynebacterium spp. are part of the microbiota of the skin and mucous membranes, human infections caused by Corynebacterium spp. have been reported and the multidrug resistance pattern of the recovered isolates was emphasised. Due to the usefulness of disk diffusion in daily practice, the purpose of this study was to compare disk diffusion with agar dilution to determine disk diffusion breakpoints and to review the antimicrobial susceptibility of the most frequent Corynebacterium spp. isolated in clinical samples.

METHODS

Susceptibility to 20 antimicrobial agents of 143 Corynebacterium spp. isolates recovered from relevant clinical samples was determined. Comparison between the disk diffusion and agar dilution methods for eight antimicrobial agents was performed to establish new breakpoints using simple linear regression analysis.

RESULTS

All of the isolates tested were susceptible to vancomycin, minocycline and linezolid. A typical susceptibility profile to β-lactam antibiotics among the different species included was not observed. Almost all isolates showed resistance to macrolides and lincosamides. Using a simple linear regression method, it was possible to establish breakpoints for penicillin, erythromycin, clindamycin, gentamicin and ciprofloxacin. However, the low correlation coefficient obtained for vancomycin, minocycline and trimethoprim/sulfamethoxazole did not allow establishment of breakpoints for the disk diffusion method.

CONCLUSION

The disk diffusion method could only be used to evaluate susceptibility to penicillin, erythromycin, clindamycin, gentamicin and ciprofloxacin. These data show that the presence of a Corynebacterium spp. isolate in a clinical sample demands the performance of antimicrobial susceptibility testing since the susceptibility profile is not predictable.

Cutaneous Corynebacterium Infection Presenting with Disseminated Skin Nodules and Ulceration

In the context of the European migrant crisis, more and more cases of cutaneous diphtheria are seen. A typical presentation includes painful cutaneous ulcerations with grayish-whitish pseudomembranes. Here we present 2 male Eritrean patients suffering from cutaneous nontoxigenic Corynebacterium diphtheriae (patient 1) and Corynebacterium striatum (patient 2) infection.

Corynebacterium striatum Bacteremia Associated with a Catheter-Related Blood Stream Infection

A 49-year-old woman visited our emergency department because of exertional dyspnea due to severe left ventricular functional failure. It progressed to disseminated intravascular coagulation and disturbance of consciousness on day 67 of admission. Gram-positive bacilli were detected from two different blood culture samples on day 67 of admission. An API-Coryne test and sequencing (1~615 bp) of the 16S rRNA gene were performed, and the strain was identified as Corynebacterium striatum. The bacterium was detected from the removed central venous catheter tip too, and the patient was diagnosed with catheter-related bloodstream infection by C. striatum. However, treatment was not effective, and the patient died on day 73 of admission.

Clinical characteristics and predictive factors for mortality in coryneform bacteria bloodstream infection in hematological patients

BACKGROUND

We examined the clinical characteristics and predictive factors for mortality in coryneform bacteria bloodstream infection in hematological patients.

METHODS

We searched for hematological patients who had positive blood cultures for coryneform bacteria at our center between April 2007 and January 2016. Patients with definite bloodstream infections were included. We started species identification in April 2014.

RESULTS

Twenty of twenty-eight cases with a positive blood culture for coryneform bacteria were regarded as definite infections. Sixteen and two patients were allogeneic and autologous hematopoietic stem cell transplantation (HSCT) recipients, respectively. Corynebacterium striatum was identified in all nine of the cases tested and one patient was co-infected with Corynebacterium amycolatum. None of the patients died directly due to coryneform bacteria infection. The survival rates at 30, 60 and 180 days were 100%, 73.7% and 51.3%, respectively. Causes of mortality included progression of the underlying disease (n = 6), other infections (n = 4) and HSCT complications (n = 2). Mixed infection (hazard ratio (HR) 5.47, 95% confidence interval (CI) 1.30-23.0), renal impairment (HR 6.31, 95% CI 1.06-37.4) and absence of a central venous (CV) catheter at the onset (HR 6.39, 95% CI 1.04-39.45) were identified as predictive factors for mortality.

CONCLUSION

Most of the coryneform bacteria bloodstream infections occurred in HSCT recipients. Contamination seemed to be less common when coryneform bacteria were detected in blood in hematological patients. Although coryneform bacteria bloodstream infection seemed to mostly be manageable, the prognosis was not desirable, particularly in patients with mixed infection, renal impairment and absence of a CV catheter.

Susceptibility to Aminoglycosides and Distribution of aph and aac(3)-XI Genes among Corynebacterium striatum Clinical Isolates

Corynebacterium striatum is an opportunistic pathogen, often multidrug-resistant, which has been associated with serious infections in humans. Aminoglycosides are second-line or complementary antibiotics used for the treatment of Corynebacterium infections. We investigated the susceptibility to six aminoglycosides and the molecular mechanisms involved in aminoglycoside resistance in a collection of 64 Corynebacterium striatum isolated in our laboratory during the period 2005–2009. Antimicrobial susceptibility was determined using E-test. The mechanisms of aminoglycoside resistance were investigated by PCR and sequencing. The 64 C. striatum were assessed for the possibility of clonal spreading by Pulsed-field Gel Electrophoresis (PFGE). Netilmicin and amikacin were active against the 64 C. striatum isolates (MICs₉₀ = 0.38 and 0.5 mg/L, respectively). Twenty-seven of the 64 C. striatum strains showed a MIC₉₀ for kanamycin > 256 mg/L, and 26 out the 27 were positive for the aph(3’)-Ic gene. Thirty-six out of our 64 C. striatum were streptomycin resistant, and 23 out of the 36 carried both the aph(3”)-Ib and aph(6)-Id genes. The gene aac(3)-XI encoding a new aminoglycoside 3-N acetyl transferase from C. striatum was present in 44 out of the 64 isolates, all of them showing MICs of gentamicin and tobramycin > 1 mg/L. CS4933, a C. striatum showing very low susceptibility to kanamycin and streptomycin, contains an aminoglycoside resistance region that includes the aph(3’)-Ic gene, and the tandem of genes aph(3”)-Ib and aph(6)-Id. Forty-six major PFGE types were identified among the 64 C. striatum isolates, indicating that they were mainly not clonal. Our results showed that the 64 clinical C. striatum were highly resistant to aminoglycosides and mostly unrelated.

Clinical and bacteriological analyses of bacteremia due to Corynebacterium striatum

BACKGROUND

Corynebacterium striatum was recently recognized as a potential pathogen of various infectious diseases. However, the clinical entity of this microorganism has not been clearly identified. Therefore, we analyzed C. striatum isolates from blood culture and explored their clinical determinants.

METHODS

We reviewed the medical records of all patients from whom C. striatum isolates were recovered from blood culture for analysis of the patients' backgrounds and clinical course including response to antimicrobial therapy and prognosis.

RESULTS

During the 5-year study period (January 2010 to December 2014), 24 C. striatum strains were isolated from blood samples, and the frequency of C. striatum bacteremia increased. The majority of the strains were multidrug resistant. All of the tested strains were susceptible to only vancomycin. The age at onset of C. striatum bacteremia encompassed all adult age groups, and at least one underlying condition was documented in all patients. Thirteen of the 24 patients were cured using appropriate antibiotics (true infection group); however, 11 of the 24 patients were cured using inappropriate antibiotic therapy or no antibiotics (contamination group). Malignancy and neutropenia significantly increased the odds of true C. striatum bloodstream infection.

CONCLUSIONS

The Corynebacterium species is often considered a contaminant when isolated in culture. Instead, particularly when the strain is isolated from blood, the species should be considered clinically relevant and identified to the species level; in addition, antimicrobial susceptibility testing is recommended.

Clinical Significance of Commensal Gram-Positive Rods Routinely Isolated from Patient Samples

Commensal bacteria from the skin and mucosal surfaces are routinely isolated from patient samples and considered contaminants. The majority of these isolates are catalase-positive Gram-positive rods from multiple genera routinely classified as diphtheroids. These organisms can be seen upon Gram staining of clinical specimens or can be isolated as the predominant or pure species in culture, raising a priori suspicion of a possible involvement in infection. With the development and adoption of matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS), suspicious isolates are now routinely identified to the species level. In this study, we performed a retrospective data review (2012 to 2015) and utilized site-specific laboratory criteria and chart reviews to identify species within the diphtheroid classification representative of true infection versus contamination. Our data set included 762 isolates from 13 genera constituting 41 bacterial species. Only 18% represented true infection, and 82% were deemed contaminants. Clinically significant isolates were identified in anaerobic wounds (18%), aerobic wounds (30%), blood (5.5%), urine (22%), cerebrospinal fluid (24%), ophthalmologic cultures (8%), and sterile sites (20%). Organisms deemed clinically significant included multiple Actinomyces species in wounds, Propionibacterium species in joints and cerebrospinal fluid associated with central nervous system hardware, Corynebacterium kroppenstedtii (100%) in breast, and Corynebacterium striatum in multiple sites. Novel findings include clinically significant urinary tract infections by Actinomyces neuii (21%) and Corynebacterium aurimucosum (21%). Taken together, these findings indicate that species-level identification of diphtheroids isolated with a priori suspicion of infection is essential to accurately determine whether an isolate belongs to a species associated with specific types of infection.

Characteristics of Multidrug-Resistant Corynebacterium spp. Isolated from Blood Cultures of Hospitalized Patients in Japan

Corynebacterium is a genus consisting of Gram-positive, rod-shaped bacteria, that is wildly distributed in nature. We report the epidemiological characterization of Corynebacterium spp. isolated from blood specimens at the Kurume University Hospital, between June 2008 and November 2011. Twenty-two strains that were likely Corynebacterium spp. were isolated from 22 hospitalized patients, of which 12 (54.5%) were identified as Corynebacterium striatum. Minimum inhibitory concentration tests were performed after biochemical and genotypic identifications. Biofilm production was detected using a 96-well microplate assay. The dissemination of C. striatum was investigated using pulsed-field gel electrophoresis (PFGE). All strains showed the tendency to be resistant to multiple drugs except vancomycin. Fourteen (82.4%) strains, including 9 C. striatum strains were capable of producing biofilms. Four distinct PFGE patterns were detected among C. striatum strains; 6 of which were identified as dominant pattern A (defined in this study) and had high biofilm production ability. During the 3-year monitoring period, these strains might have repeatedly infected the patients or could have readily colonized the hospital environments. C. striatum appeared to be a potential risk factor for bloodstream infections in hospitalized patients. More surveillance and enhanced control strategies are necessary to decrease Corynebacterium spp. infections in hospitals.

Corynebacterium striatum empyema and osteomyelitis in a patient with advanced rheumatoid arthritis

Corynebacterium striatum, which is a common coloniser of human skin and mucous membranes, is increasingly being recognised as an emerging pathogen. We present a case of a 69-year-old woman with empyema and osteomyelitis caused by C. striatum. To the best of our knowledge, this is the first case where these two infections from this bacterium were identified together in the same individual.

A case of fatal sepsis due to multidrug-resistant Corynebacterium striatum

BACKGROUND

Although non-diphtheria corynebacteria have traditionally been regarded as avirulent members of human bacterial flora, their pathogenic potential is increasingly recognized in our time. Reasons for this include the prolonged survival of severely ill and immunocompromised patients, the development of more invasive diagnostic and therapeutic procedures and the sub-optimal use of antibiotics that disrupts normal microbial balance and favors superinfections.

CASE REPORT

We present a rare case of sepsis due to multidrug-resistant Corynebacterium striatum in a 76-year-old host. The patient suffered from myelodysplastic syndrome and was on corticosteroid treatment due to atopic dermatitis. He had, also, a recent hospital admission and received a course of broad-spectrum antibiotics due to lower respiratory infection. The patient responded neither to empiric nor to targeted treatment and finally succumbed.

CONCLUSION

Diphtheroids are emerging pathogens capable of causing severe opportunistic infections. Their multidrugresistant nature renders treatment problematic and poses a threat to the currently established antimicrobial stewardship programs. Hippokratia 2016, 20(1): 67-69.

Biofilm production by multiresistant Corynebacterium striatum associated with nosocomial outbreak

Corynebacterium striatum is a potentially pathogenic microorganism that causes nosocomial outbreaks. However, little is known about its virulence factors that may contribute to healthcare-associated infections (HAIs). We investigated the biofilm production on abiotic surfaces of multidrug-resistant (MDR) and multidrug-susceptible (MDS) strains of C. striatum of pulsed-field gel electrophoresis types I-MDR, II-MDR, III-MDS and IV-MDS isolated during a nosocomial outbreak in Rio de Janeiro, Brazil. The results showed that C. striatum was able to adhere to hydrophilic and hydrophobic abiotic surfaces. The C. striatum 1987/I-MDR strain, predominantly isolated from patients undergoing endotracheal intubation procedures, showed the greatest ability to adhere to all surfaces. C. striatum bound fibrinogen to its surface, which contributed to biofilm formation. Scanning electron microscopy showed the production of mature biofilms on polyurethane catheters by all pulsotypes. In conclusion, biofilm production may contribute to the establishment of HAIs caused by C. striatum.

Respiratory infection by Corynebacterium striatum: epidemiological and clinical determinants

The increasing prevalence of advanced chronic respiratory disease, with frequent exposure to broad-spectrum antibiotics for repeated and prolonged hospitalizations, favours the emergence of nosocomial respiratory infection by Gram-positive bacteria, such as outbreaks of Corynebacterium striatum. There is little evidence about patterns of respiratory infection, transmission and adaptive ability of this pathogen. Seventy-two C. striatum isolates from 51 advanced respiratory patients, mainly chronic obstructive pulmonary disease, were studied during 38 months. Patients were 74.8 ± 8.6 years old and 81.9% were men, who had required an average of 2.2 hospitalizations and 63.5 days in the hospital in the previous year. Of 49 isolates from 42 patients we were able to identify 12 clones by multilocus sequence analysis (MLSA), nine phenotypic variants and 22 antibiotic susceptibility patterns, and we determined their clinical and epidemiological determinants. MLSA allows identification of the existence of nosocomial outbreaks by transmission of the same or different clones, the persistence of the same clone in the environment or in patient airways for months. The study showed the high variability and adaptive capacity of the isolates, the antibiotic multidrug-resistance in all of them, and their contribution to a high morbidity and mortality (41%) during the study period.

Epidemiological investigation of a nosocomial outbreak of multidrug-resistant Corynebacterium striatum at one Belgian university hospital

During an 8-month period, 24 Corynebacterium striatum isolates recovered from lower respiratory tract specimens of 10 hospitalized patients were characterized. The organisms were identified by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) and by 16S rRNA gene sequencing. The cluster of C. striatum exclusively affected patients who had been admitted to an intensive care unit and/or subsequently transferred to one medium-size respiratory care unit. Prolonged duration of hospitalization, advanced stage of chronic obstructive pulmonary disease, recent administration of antibiotics and exposure to an invasive diagnostic procedure were the most commonly found risk factors in these patients. Seven patients were colonized and three infected. All strains displayed a similar broad spectrum resistance to antimicrobial agents, remaining susceptible to vancomycin only. Typing analysis by MALDI-TOF MS and by semi-automated repetitive sequence-based PCR (DiversiLab typing) showed that all outbreak-associated C. striatum isolates clustered together in one single type while they differed markedly from epidemiologically unrelated C. striatum isolates. Pulsed-field gel electrophoresis (PFGE) profiles revealed three distinct PFGE types among the C. striatum isolates associated with the outbreak while all external strains except one belonged to a distinct type. We conclude that C. striatum is an opportunistic nosocomial pathogen in long-term hospitalized patients and can be at the origin of major outbreaks. The routine use of MALDI-TOF MS greatly facilitated the recognition/identification of this organism in clinical samples and this technique could also offer the potential to be used as an easy and rapid epidemiological typing tool for outbreak investigation.

Clonal multidrug-resistant Corynebacterium striatum within a nosocomial environment, Rio de Janeiro, Brazil

Corynebacterium striatum is a potentially pathogenic microorganism with the ability to produce outbreaks of nosocomial infections. Here, we document a nosocomial outbreak caused by multidrug-resistant (MDR) C. striatum in Rio de Janeiro, Brazil. C. striatum identification was confirmed by 16S rRNA and rpoB gene sequencing. Fifteen C. striatum strains were isolated from adults (half of whom were 50 years of age and older). C. striatum was mostly isolated in pure culture from tracheal aspirates of patients undergoing endotracheal intubation procedures. The analysis by pulsed-field gel electrophoresis (PFGE) indicated the presence of four PFGE profiles, including two related clones of MDR strains (PFGE I and II). The data demonstrated the predominance of PFGE type I, comprising 11 MDR isolates that were mostly isolated from intensive care units and surgical wards. A potential causal link between death and MDR C. striatum (PFGE types I and II) infection was observed in five cases.

Microbiological investigation and clinical significance of Corynebacterium spp. in respiratory specimens

The purpose of this retrospective study was to evaluate the pathogenic role of Corynebacterium species in lower respiratory tract infections as well as their routine laboratory investigation. From April 2007 to August 2009, 27 clinical isolates were significantly recovered from respiratory specimens of 27 different patients clinically suspected of having lower respiratory tract infections. The average age of patients was 65 years, while 22 (81%) patients presented at least 1 predisposing condition. Of the 27 patients, 15 (56%) were classified as infected according to Centers for Disease Control and Prevention/National Healthcare Safety Network criteria, with 93% of infections being hospital acquired. All isolates were accurately identified to the species level using molecular methods (i.e., 17 Corynebacterium pseudodiphtheriticum, 7 Corynebacterium striatum, and 3 Corynebacterium accolens), whereas phenotypic methods remained frequently unreliable for identifying C. striatum and C. accolens strains. All tested isolates were susceptible to amoxicillin, imipenem, vancomycin, linezolid, and tigecycline, whereas most of them were resistant to erythromycin.

Identification and diversity of multiresistant Corynebacterium striatum clinical isolates by MALDI-TOF mass spectrometry and by a multigene sequencing approach

BACKGROUND

The genus Corynebacterium is composed of gram-positive bacteria that are widely distributed throughout the environment; these bacteria are also part of the normal microbiota of human skin and mucous membranes. Multiple studies have shown that species of this genus, including C. striatum, become pathogenic to humans under special conditions. Our aim was to determine the characteristics of clinical multiresistant strains of C. striatum that were isolated in our geographical region, to determine their diversity, and to compare them with the type strain and with related species. We studied fifty-two strains of C. striatum isolated from different hospitals from Mallorca, Spain, mainly from the Hospital Joan March in Bunyola, Mallorca. Most of the strains were isolated from sputum cultures of respiratory samples from patients with chronic obstructive pulmonary disease. To gain further insight into the genetic diversity of the strains, we analysed several housekeeping genes and other genes associated with antibiotic resistance. Strains were also characterised phenotypically by their antibiotic resistance profiles and by MALDI-TOF mass spectrometry analysis.

RESULTS

The ITS1 region, gyrA and rpoB were chosen as the appropriate genes in the C. striatum genome to study the genetic diversity of C. striatum species and to discriminate between strains. After analysing these three genes, four sequence types (ST2, ST4, ST1 and ST11) were found to be the most abundant. Splits tree analysis of the strains demonstrated that these clinical isolates did not share any alleles with the type strain of the species. Recombination was detected within all of the C. striatum isolates, and different clonal populations were detected within the samples.

CONCLUSIONS

Our results demonstrate that the isolates were best identified using gene-based molecular methods; using these methods, the isolated strains were determined to be different from the type strain of C. striatum. The ITS1 region and the gyrA and rpoB genes were selected because of their variability and were the most useful tools for discriminating between strains. The phenotype and antibiotype characteristics of the strains did not seem suitable for typing purposes. MALDI-TOF mass spectrometry can be a useful method for identifying and discriminating between C. striatum strains.

Corynebacterium striatum bacteremia associated with central venous catheter infection

Corynebacterium striatum (C striatum) has been considered a contaminant of blood culture in past decades. Here we report the case of a patient with acute deterioration of chronic renal failure. She received hemodialysis and died from C striatum bacteremia. By using a randomly amplified polymorphic DNA (RAPD) method, we found that an association existed between C striatum from the bloodstream and that from the central venous catheter. We suggest that C striatum could be a pathogen of bloodstream infection in patients with such a catheter in place.

[Cystitis and haematuria due to Corynebacterium striatum. A case report and review]

We herewith report the first case of uncomplicated urinary tract infection due to Corynebacterium striatum in an ambulatory patient without any other predisponent risk factors. C. striatum is a ubiquitous saprophyte of human skin and mucous membranes, which has been occasionally associated with infection in patients hospitalized or immunocompromised patients with underlying diseases. We conclude that C. striatum should be considered an emerging pathogen in both immunocompetent and immunocompromised hosts.

Nosocomial valve endocarditis due to corynebacterium striatum: a case report

Staphylococcus aureus, Coagulase-negative staphylococci, and Enterococci sp. are the usual pathogens involved in nosocomial bacterial endocarditis. Corynebacterium species isolation in blood specimens is usually considered to be a contaminant. We present an interesting case of native mitral valve endocarditis in a 73 year old African American female that was diagnosed days after she was discharged from our institution. The infection was cleared with medical therapy alone.

Nosocomial outbreak of Corynebacterium striatum infection in patients with chronic obstructive pulmonary disease

We describe an unusual cluster of Corynebacterium striatum infections in 21 patients with chronic obstructive pulmonary disease (COPD) admitted to a medium-size respiratory unit. Eleven isolates from eight patients occurred simultaneously within a month. C. striatum is a potentially pathogenic microorganism with the ability to produce nosocomial infectious outbreaks and respiratory colonization in patients with advanced COPD.

A spontaneous joint infection with Corynebacterium striatum

Corynebacterium striatum is a ubiquitous saprophyte with the potential to cause bacteremia in immunocompromised patients. Until now, spontaneous infection of a natural joint has not been reported. When phenotyping failed, gene sequencing was used to identify the species. The isolate demonstrated high-level resistance to most antibiotics.

Emergence of multidrug-resistant Corynebacterium striatum as a nosocomial pathogen in long-term hospitalized patients with underlying diseases

During a 53-month period (March 1994 to August 1998), 48 Corynebacterium striatum isolates recovered from clinical specimens were characterized. The organisms were identified by both phenotypic characteristics and 16S rRNA gene sequence analysis. Thirty-six (75%) were isolated from sputum/bronchial aspirates, 10 (21%) from wound exudates/pus, 1 (2%) from vaginal discharge, and 1 (2%) from an otorrheic specimen. All 48 patients had been hospitalized for treatment of an underlying disease and had received antibiotics previously. The C. striatum isolates were considered pathogenic based on their abundance within polymorphonuclear neutrophils and their dominant growth in culture. Sensitivities of isolates to 11 antibiotics were determined by broth microdilution. MIC90 values of the isolates were 1 microg/mL for vancomycin, 16 microg/mL for penicillin and ampicillin, 32 microg/mL for minocycline, and > or = 32 microg/mL for cephalosporins, imipenem, ofloxacin, and macrolides. Restriction fragment-length polymorphism analysis with pulsed-field gel electrophoresis was used to determine the clonal identity. The pulse-field gel electrophoresis profiles revealed 14 distinct patterns with 20 subtypes. The isolates for the nosocomial outbreaks of C. striatum included 3 types (A, D, and E) with 4 subtypes (A1, A2, D2, and E). All 4 genotypes had broad-spectrum resistance to antimicrobial agents. Furthermore, type E strain isolated from 3 patients in the same ward was sensitive only to vancomycin. We conclude that C. striatum should be considered an emerging multidrug-resistant nosocomial pathogen in patients hospitalized for a prolonged period and/or in immunocompromised patients with such underlying conditions as cerebrovascular disease, pulmonary disease, diabetes, or malignancy.

Fatal pulmonary infection associated with a novel organism, "para-streptomyces abscessus"

Actinomycetes are increasingly recognized as pathogenic in the immunocompromised host. We isolated an asporogenous, nonmotile, aerobic gram-positive rod from a transplant recipient with a fatal pulmonary infection. The pathology was similar to that associated with Rhodococcus equi, including intra-histiocytic localization. The organism was relatively inert in standard biochemical tests. 16S rRNA gene sequencing indicated a potentially unique organism most closely related to the genus Streptomyces, for which we propose the name "Para-streptomyces abscessus."

Corynebacterium striatum: an underappreciated community and nosocomial pathogen

Corynebacterium striatum (CS) is an underappreciated human pathogen that has been associated with serious infections in both immunocompetent and immunocompromised hosts. CS infections tend to be more frequent in males and major infection sites have included blood stream, lung, and central nervous system. Most are nosocomially acquired and there is a significant association with medical devices ranging from intravascular catheters to central nervous system drainage devices. Empiric therapy with vancomycin is advisable as susceptibility to other agents is variable. Treatment may also include removal of foreign material such as an intravascular catheter. The present review describes the wide spectrum of infections associated with CS and we add a unique case of CS pancreatic abscess where treatment included linezolid.

Septicaemia due to Corynebacterium striatum: molecular confirmation of entry via the skin

Septicaemia due to Corynebacterium striatum occurs infrequently. A case of C. striatum septicaemia with a known skin focus is reported in a 69-year-old male with ischaemia, refractory anaemia and treated for thyroid cancer. The characterization and typing of blood and cutaneous isolates was carried out using biochemical and DNA molecular typing methods to analyse the isolates. This is the first reported case with a documented source.

Multidrug-resistant Corynebacterium striatum pneumonia in a heart transplant recipient

Corynebacterium striatum is a rare, but likely underreported, cause of serious infections in immunocompromised hosts and generally is susceptible to multiple classes of antimicrobial agents. Here we report the first case of C. striatum infection in a solid organ transplant recipient. Three years after heart transplantation, a 58-year-old man developed bilateral pneumonia and pulmonary embolism. He did not improve with levofloxacin, piperacillin/tazobactam, and heparin treatment. A homogeneous population of abundant gram-positive rods was repeatedly demonstrated in sputum and bronchoalveolar lavage fluid, and C. striatum was grown in pure culture. The isolate was unusual for its multidrug-resistant (MDR) antimicrobial susceptibility pattern. The pneumonia resolved with 4 weeks of vancomycin therapy, in combination with rifampin given only during the first 2 weeks of treatment. The isolation of coryneforms ("diphtheroids") is often attributed to contamination. Their abundant presence on direct examination of specimens and/or their growth in pure culture suggest a pathogenic role, however, and indicate the need for accurate microbiological identification, particularly in immunocompromised hosts who have been hospitalized and previously treated with antibiotics. Combination therapy that includes vancomycin may be the most prudent treatment for MDR C. striatum infections.

Tsukamurella strandjordae sp. nov., a proposed new species causing sepsis

We have isolated a gram-positive, weakly acid-alcohol-fast, irregular rod-shaped bacterium from cultures of blood from a 5-year-old girl with acute myelogenous leukemia. This isolate was compared with 14 other strains including reference strains of Tsukamurella species by a polyphasic approach based on physiological and biochemical properties, whole-cell short-chain fatty acid and mycolic acid analyses, DNA-DNA hybridization, and sequencing of the 16S rRNA gene. This isolate represents a new taxon within the genus Tsukamurella for which we propose the name Tsukamurella strandjordae sp. nov. Our study also revealed that Tsukamurella paurometabola ATCC 25938 represents a misnamed Tsukamurella inchonensis isolate and confirms that Tsukamurella wratislaviensis belongs to the genus Rhodococcus.

[Significant bacteremias by Corynebacterium amycolatum: an emergent pathogen]

BACKGROUND

Corynebacterium sp. is an extremely varied genus which includes little known species and of which only Corynebacterium diphteriae, Corynebacterium urealyticum and Corynebacterium jeikeium are considered indisputable pathogens. Other species, such as C. amycolatum are at present being reconsidered as causative agents in infectious pathologies, partly on account of our greater aquaintance and improved identification techniques for these microorganisms and partly on account of the growing number of immunocompromised patients in whom all their pathogenic capacity is usually able to develope. We present 3 cases of significant bacteremia by C. amycolatum.

METHODS

Bacterial isoliations from blood culture were obtained using the Vital Systems. Identification was performed by means of Gran stain, colony morphology, the results of numerous biochemical tests (including the Api Coryne systems), the behaviour of the strains against the vibriostatic agent O/129 and the antibiotic susceptibility pattern obtained with the E-test.

RESULTS

The three isolates of C. amycolatum were obtained from patients after a lenghtly hospitalization, multi-instrumentation and who had severe underlying disease. All three presented with concomitant isolates of C. amycolatum from other sites: sputum, wound and catheter respectively, which could explain the origin of the bacteremia. Colony morphology, antibiotic susceptibility patterns, resistance to the vibriostatic agent O/129 and the results of the biochemical test carried out were similar to those previously describe in the literature.

CONCLUSIONS

C. amycolatum should be born in mind as a agent responsable for significant and severe pathology in this type of patient. In addition, it as certain specific characteristics which assits in its identification in the normal micr

Application of 16S rRNA gene sequencing to identify Bordetella hinzii as the causative agent of fatal septicemia

We report on the first case of fatal septicemia caused by Bordetella hinzii. The causative organism exhibited a biochemical profile identical to that of Bordetella avium with three commercial identification systems (API 20E, API 20 NE, and Vitek GNI+ card). However, its cellular fatty acid profile was not typical for either B. avium or previously reported strains of B. hinzii. Presumptive identification of the patient's isolate was accomplished by traditional biochemical testing, and definitive identification was achieved by 16S rRNA gene sequence analysis. Phenotypic features useful in distinguishing B. hinzii from B. avium were production of alkali from malonate and resistance to several antimicrobial agents.

Differentiation of Corynebacterium amycolatum, C. minutissimum, and C. striatum by carbon substrate assimilation tests

We tested the carbon substrate assimilation patterns of 40 Corynebacterium amycolatum strains, 19 C. minutissimum strains, 50 C. striatum strains, and 1 C. xerosis strain with the Biotype 100 system (bioMérieux, Marcy-l'Etoile, France). Twelve carbon substrates of 99 allowed discrimination among the species tested. Additionally, assimilation of 3 of these 12 carbon substrates (maltose, N-acetyl-D-glucosamine, and phenylacetate) was tested with the API 20 NE identification system (bioMérieux). Since concordant results were observed with the two systems for these three carbon substrates, either identification system can be used as a supplementary tool to achieve phenotypic differential identification of C. amycolatum, C. minutissimum, and C. striatum in the clinical microbiology laboratory.

Corynebacterium imitans sp. nov. isolated from patients with suspected diphtheria

A 5-month-old boy of a Romanian family traveling via Ukraine to Poland developed a respiratory disease that resembled and that was initially diagnosed as pharyngeal diphtheria. The child recovered after treatment with antidiphtheria antitoxin. A coryneform bacterium had been isolated from a nasopharyngeal specimen from the child and was initially identified as an atypical Corynebacterium diphtheriae strain. Seven adults who had contact with either the child or an adult contact person also developed symptoms of pharyngeal diphtheria, were also treated with antitoxin, and recovered uneventfully. Coryneform bacteria similar to that originating from the index patient were also isolated from the throat swabs of three adults. Detailed biochemical and chemotaxonomic investigations revealed that the coryneform bacteria belonged to the genus Corynebacterium and could be differentiated from all other defined species of this genus. Ribotyping and pulsed-field gel electrophoresis demonstrated that all four patients' isolates were of clonal origin. The diphtheria toxin gene and its product were not detected either by PCR assays or by the Elek test, making a possible disease association of the Corynebacterium more unlikely. Comparative 16S rRNA gene sequence analysis revealed that the coryneform bacterium represented a new subline within the genus Corynebacterium, for which the name Corynebacterium imitans sp. nov. is proposed. The type strain is NCTC 13015 (DSM 44264; CCUG 36877).

Clinical significance of Corynebacterium striatum isolated from human samples

OBJECTIVE: To evaluate the clinical significance of and describe factors associated with Corynebacterium striatum infection. METHODS: A retrospective chart review was performed of the C. striatum isolated in a university hospital from January 1991 to July 1995. C. striatum was identified using conventional methods, the API CORYNE system and cellular fatty acid profiles. RESULTS: In the study period, C. striatum was isolated from clinical samples in 127 patients. In 49 patients, data from clinical charts were considered insufficient for evaluation. In 26 cases, the microorganism was considered to be the etiologic agent of an infectious process. In the remaining 52 patients, the organism was considered to be a colonizer. Before the infection all the patients had been hospitalized for some underlying condition, and 22 (85%) of them had received antibiotics previously. Six patients died. In two of them, death was a consequence of their underlying disease and in the remaining four, death was related to the C. striatum infection. CONCLUSIONS: C. striatum, a microorganism traditionally considered to be an avirulent member of the normal human nasopharyngeal and skin flora, may opportunistically cause infections in hospitalized patients with underlying diseases and previous antibiotic treatments.