P.O. Box 131375, Bryanston, 2074 Ground Floor, Block 5 Bryanston Gate, 170 Curzon Road Bryanston, Johannesburg, South Africa 804 Flatrock, Buiten Street, Cape Town, 8001 www.thistle.co.za Tel: +27 (011) 463 3260 Fax: +27 (011) 463 3036 Fax to Email: + 27 (0) 86-557-2232 e-mail : [email protected] Please read this section first The HPCSA and the Med Tech Society have confirmed that this clinical case study, plus your routine review of your EQA reports from Thistle QA, should be documented as a “Journal Club” activity. This means that you must record those attending for CEU purposes. Thistle will not issue a certificate to cover these activities, nor send out “correct” answers to the CEU questions at the end of this case study. The Thistle QA CEU No is: MT-2014/004. Each attendee should claim THREE CEU points for completing this Quality Control Journal Club exercise, and retain a copy of the relevant Thistle QA Participation Certificate as proof of registration on a Thistle QA EQA. MICROBIOLOGY LEGEND CYCLE 36 ORGANISM 1 Enterococcus casseliflavus Enterococcus is a genus of lactic acid bacteria of the phylum Firmicutes. Enterococci are Gram-positive cocci that often occur in pairs (diplococci) or short chains, and are difficult to distinguish from streptococci on physical characteristics alone. Two species are common commensal organisms in the intestines of humans: E. faecalis (90-95%) and E. faecium (5-10%) but are also important pathogens responsible for serious infections. Rare clusters of infections occur with other species, including E. casseliflavus, E. gallinarum, and E. raffinosus. With increasing antibiotic resistance, enterococci are recognized as feared nosocomial pathogens that can be challenging to treat. Enterococcus species are hardy, facultative anaerobic organisms that can survive and grow in many environments. In the laboratory, enterococci are distinguished by their morphologic appearance on Gram stain and culture (gram-positive cocci that grow in chains) and their ability to (1) hydrolyze esculin in the presence of bile, (2) grow in 6.5% sodium chloride, (3) demonstrate pyrrolidonyl arylamidase and leucine aminopeptidase, and (4) react with group D antiserum. Members of the genus Enterococcus were classified as Group D Streptococcus until 1984, when genomic DNA analysis indicated a separate genus classification would be appropriate. Though they are not capable of forming spores, enterococci are tolerant of a wide range of environmental conditions like extreme temperature (10-45°C) & pH (4.5-10.0). Enterococci typically exhibit gamma-hemolysis on sheep's blood agar. Enterococcus faecalis and Enterococcus faecium are the most prevalent species cultured from humans, accounting for more than 90% of clinical isolates. Other enterococcal species known to cause human infection include Enterococcus avium, Enterococcus gallinarum, Enterococcus casseliflavus, Enterococcus durans, Enterococcus raffinosus and Enterococcus mundtii. E. faecium represents most vancomycin-resistant enterococci (VRE). Pathology Important clinical infections caused by Enterococcus include urinary tract infections, bacteraemia, bacterial endocarditis, diverticulitis, and meningitis. Sensitive strains of these bacteria can be treated with ampicillin, penicillin and vancomycin. Thistle QA is a SANAS accredited organisation, No: PTS0001 Accredited to ISO 17043 Certificate available on request or at www.sanas.co.za Page 1 of 3 P.O. Box 131375, Bryanston, 2074 Ground Floor, Block 5 Bryanston Gate, 170 Curzon Road Bryanston, Johannesburg, South Africa 804 Flatrock, Buiten Street, Cape Town, 8001 www.thistle.co.za Tel: +27 (011) 463 3260 Fax: +27 (011) 463 3036 Fax to Email: + 27 (0) 86-557-2232 e-mail : [email protected] From a medical standpoint, an important feature of this genus is the high level of intrinsic antibiotic resistance. Some enterococci are intrinsically resistant to β-lactam-based antibiotics (penicillins, cephalosporins, carbapenems), as well as many aminoglycosides. In the last two decades, particularly virulent strains of Enterococcus that are resistant to vancomycin (vancomycin-resistant Enterococcus, or VRE) have emerged in nosocomial infections of hospitalized patients, especially in the US. VRE may be treated with quinupristin/dalfopristin (Synercid) with response rates of approximately 70%. Tigecycline has also been shown to have anti-enterococcal activity as has rifampicin. Mortality/Morbidity In general, the virulence of enterococci is lower than that of organisms such as S. aureus. However, enterococcal infections often occur in debilitated patients and as part of polymicrobial infections. These factors limit the ability of investigators to determine the independent contribution of enterococcal infections to mortality and morbidity. Vancomycin-resistant bacteremia increases the length of hospital stay by an average of 2 weeks, and studies calculate an attributable mortality rate of up to 37% from these infections. Mortality rates associated with enterococcal infections may exceed 50% in critically ill patients, those with solid tumors, and some transplant patients. Bacteremia caused by VRE strains carries higher mortality rates than does bacteremia due to vancomycin-susceptible strains. Despite the availability of antimicrobial agents with greater potency against VRE, one study of 113 patients with VRE bacteremia reported that such agents did not significantly change clinical outcomes. Sex In general, enterococcal infections are distributed equally between the sexes. Although urinary tract infections are more common in healthy women than in healthy men, enterococci are an uncommon cause of uncomplicated cystitis in this setting. Age Enterococcal infections are more common in elderly patients because of various associated factors that are more common in these patients. For example, urinary tract catheterization and instrumentation are more common in elderly populations. Abdominal surgery for diverticulitis or biliary tract disease is also performed more commonly in elderly persons. In a recent study, most cases of enterococcal endocarditis occurred in elderly individuals. In neonates, enterococci occasionally cause bacteremia and meningitis. Outbreaks of enterococcal infections, including VRE infections, have been reported in neonatal ICUs, pediatric ICUs, and hematology/oncology units, but, overall, VRE infections are less common in pediatric patients than in adults Enterococcus casseliflavus Physiology and classification Enterococcus casseliflavus was formerly known as Streptococcus faecium subsp. casseliflavus or Streptococcus casseliflavus. Ent. casseliflavus is normally pigmented and motile, but non-pigmented and non- motile strains may occur. Occurrence and habitat Ent. casseliflavus is associated with plant material. Thistle QA is a SANAS accredited organisation, No: PTS0001 Accredited to ISO 17043 Certificate available on request or at www.sanas.co.za Page 2 of 3 P.O. Box 131375, Bryanston, 2074 Ground Floor, Block 5 Bryanston Gate, 170 Curzon Road Bryanston, Johannesburg, South Africa 804 Flatrock, Buiten Street, Cape Town, 8001 www.thistle.co.za Tel: +27 (011) 463 3260 Fax: +27 (011) 463 3036 Fax to Email: + 27 (0) 86-557-2232 e-mail : [email protected] Pathogenicity This species is found infrequently in infections. Identification Pigmentation, motility and intrinsic vancomycin-low level resistance are most useful characteristics. The differentiation from other yellow pigmented enterococci is shown in table 1 and the characteristics distinguishing between this species and Ent. gallinarum in table 2. E. casseliflavus E. faecalis Table 1: Tests useful in the differentiation of yellow Table 2: Tests useful in the differentiation of members of pigmented enterococci the Enterococcus gallinarum species group Characteristics Ent. Ent. Ent. Test Ent. Ent. casseliflavus mundtii sulfureus gallinarum casseliflavus Vancomycin + - ? Yellow pigment - + resistance Hippurate D+ 1 Motility D+ - - Acid from Sorbitol D - Arginine dihydrolase + + - Glycerol - D Group D antigen + + - Glycogen D - Acid produced from Β-haemolysis on horse blood D+ - L-Arabinose + + - agar Glycerol - D - Α-haemolysis on sheep blood - D+ agar Gluconate + - + Inulin + -(D -?) - Α-Methyl-D-glucoside + - + Rhamnose D+ D+ - Sorbitol - D - D – Different or variable: D+ usually positive; D- usually negative References 1. The Genera of Lactic Acid Bacteria edited by B.J. Wood, W.H.N Holzapfel 2. http://en.wikipedia.org/wiki/Enterococcus Questions 1. Discuss how you would distinguish between E. faecalis and E. casseliflavus in your lab. 2. What are the morphological characteristics of the genus Enterococcus? 3. Discuss the pathophysiology of Enterococci. \ Thistle QA is a SANAS accredited organisation, No: PTS0001 Accredited to ISO 17043 Certificate available on request or at www.sanas.co.za Page 3 of 3 .