Description Of The Organism Taxonomic History

Rosenbach provided the first taxonomic description of Staphylococcus in 1884 when he divided the genus into Staphylococcus aureus and Staphylococcus albus (Rosenbach 1884), although Pasteur and Ogston had observed spherical bacteria in abscess pus 4 years earlier (Ogston 1880 Pasteur 1880). The staphylococci and a group of saprophytic, tetrad-forming micrococci were placed into the genus Micrococcus by Zopf in 1885 (Zopf 1885) and subsequently separated again by Fl gge. Evans, Bradford and...

Staphylococcus Aureus And The Human Host Staphylococcus aureus Carriage

Three S. aureus carriage patterns have been described in the healthy adult population, with approximately 20 of individuals being persistent S. aureus carriers, about 60 intermittent carriers and 20 persistent non-carriers (Kluytmans, van Belkum and Verbrugh 1997). This represents a useful framework during the study of S. aureus carriage (Peacock, de Silva and Lowy 2001) and has become accepted and widely quoted for many years. A review of the few longitudinal studies that are to be found in...

Info

The global population of pneumococci consists of more than 90 serotypes, but human infection colonisation is dominated by a relatively small number of these. Multilocus sequence typing has shown that some sequence types define strains with an increased capacity to cause invasive disease (Enright and Spratt, 1998). These apparently successful clones may have gathered a collection of genes (or have enhanced expression of a group of genes) that confers a selective advantage that shifts the...

Intraabdominal and Pelvic Infections

Enterococci are frequently found in intra-abdominal and pelvic infections, including salpingitis, endometritis and abscesses after cesarean section, but very rarely as the sole agent. The role of enterococci in the early phases of these infections remains controversial, since most of these resolve with antibiotics that do not specifically target enterococci, although occasionally breakthrough enterococcal bacteremia does occur. Animal experiments show that enterococci act synergistically with...

Eradication of S aureus Carriage

Rates of S. aureus infection are higher in carriers than in non-carriers in a range of clinical settings (Weinstein 1959 Yu etal. 1986 Luzar etal. 1990 Weinke etal. 1992). This is consistent with the finding that individuals are usually infected with their own carriage isolate (Yu etal. 1986 Luzar etal. 1990 Nguyen etal. 1999 von Eiff etal. 2001b). Temporary eradication of carriage has been reported to result in a reduction in nosocomial infection in several patient groups and has been the...

Clinical Infections

Historically, E. faecalis, E. faecium and other species (e.g. Entero-coccus gallinarum, Enterococcus avium, Enterococcus casseliflavus and Enterococcus raffinosus) accounted for 80-90 , 5-20 and 2-4 of all enterococcal infections, respectively (Maki and Agger, 1988 Lewis and Zervos, 1990 Patterson etal., 1995). However, in the 1990s, a shift to a higher incidence of E. faecium infections has been observed in the United States, coincident with increased antibiotic pressure and development of...

Clinical Presentation of Disease

All P-haemolytic streptococci cause colonisation and superficial infection of epithelial and mucosal surfaces. The clinical scenarios are summarised in Table 1.3 and, for the purposes of this description, include all conditions affecting the upper respiratory tract. These infections are only rarely associated with bacteraemia. The occurrence of streptococcal bacteraemia in a patient with streptococcal pharyngitis should prompt a search for additional, more deep-seated foci of infection....

Clinical Syndromes

Streptococcus pneumoniae causes infection of the bronchi, lungs, sinuses and middle ear by direct spread from the site of nasopharyngeal colonisation and of the CNS, peritoneal cavity, bones, joints and heart valves by haematogenous spread. Local extension to the CNS may also result in recurrent meningitis in patients who have a dural defect. Primary bacteraemia (i.e. one without identifiable source) is particularly common in children aged 6-24 months - patients with this syndrome are often...

Description Of The Genus Biochemical Characteristics

Enterococci are Gram-positive, facultatively anaerobic cocci that typically grow in pairs or short chains. They are catalase negative, although a weak pseudocatalase is occasionally seen. Most strains have the ability to grow in the presence of 6.5 sodium chloride, at 10 C and at 45 C and at pH 9.6 and can survive at 60 C for 30min. Enterococci are capable of hydrolyzing esculin in the presence of bile, and most strains react with group D antisera. Some react also with group Q antisera....

Description Of The Organisms Current Taxonomic Status

Since the 1980s the genus Streptococcus has undergone considerable upheaval including the removal of lactic and enteric species into separate genera (Lactococcus and Enterococcus, respectively). Additionally, many new genera of Gram-positive cocci that grow in pairs or chains were established, primarily through reclassification from the genus Streptococcus by genotypic and phenotypic characteristics. For reviews, see Whiley and Beighton (1998) and Facklam (2002). Classification of species that...

Endocarditis

Enterococci are the third most common cause of infective endocarditis, following viridans streptococci and S. aureus, and account for 5-20 of cases (Megran, 1992). E. faecalis is most often the species isolated, but other enterococcal species also cause endocarditis. Enterococcal endocarditis has an acute or, more frequently, subacute onset, affects men (especially elderly men) more frequently than women and often has a genitourinary origin, although GI or biliary tract sources are also...

General Introduction

Streptococcal diseases such as scarlet fever, erysipelas and puerperal fever were recognised as major problems for centuries before characterisation of the causative organisms. The first attempts to differentiate streptococci were probably made by Schottm ller in 1903, who used haemolysis to distinguish them. The -haemolytic streptococci, characterised by the production of clear zones of haemolysis around colonies following overnight incubation on blood agar, turned out to contain some of the...

Growth Characteristics

It has been known for decades that enterococci have complex growth requirements. E. faecalis has been shown to grow well on Davis minimal medium (consisting of salts, citrate, thiamine, glucose and agar) supplemented with additional vitamins (biotin, calcium pantothenic acid, pyridoxine, nicotinic acid, riboflavin and folic acid) plus 20 amino acids (Murray etal, 1993). By deleting individual amino acids from this medium, it was shown that most of 23 E. faecalis strains tested were prototrophic...

Habitat

Enterococci are usual inhabitants of the gastrointestinal (GI) tracts of warm-blooded animals and are also found in insects and plants. E. faecalis is usually more common in human feces than E. faecium, averaging 105-107 and 104-105 colony-forming units (CFU) per gram, respectively, but E. faecium predominates especially in the hospital setting (Murray, 1990 Suppola etal, 1996). Enterococci are less frequently found at other sites such as vagina, skin, oral cavity and dental plaque. Enterococci...

Introduction

The genus Streptococcus consists of Gram-positive cocci that are facultatively anaerobic, nonsporing and catalase negative, with cells arranged in chains or pairs. Their nutritional requirements are complex, and carbohydrates are fermented to produce L-(+)-lactic acid as the main end product. All streptococci are obligate parasites of mammals, and within the genus are many species that are important pathogens of humans and domestic animals as well as many well-known opportunistic pathogens. The...

Invasive GAS Infections Figure

Invasive GAS disease has been the subject of several studies since the late 1980s and early 1990s because of its apparent reemergence during this period. Although the common manifestation of invasive GAS disease is cellulitis and other types of skin and soft-tissue infections (almost 50 of invasive disease cases), it is notoriously difficult to diagnose microbiologically because bacterial isolates are seldom recovered from infected tissue. Most invasive infections are confirmed because of...

Laboratory Diagnosis And Identification

Serological grouping provides the first precise method for identifying the P-haemolytic streptococci, in particular the human pathogens of Lancefield groups A, B, C and G. The main characteristics of these P-haemolytic streptococci are summarised in Table 1.8. Isolates from primary culture are traditionally identified by colony morphology, Gram stain, catalase test and Lancefield grouping. If Lancefield grouping does not provide sufficient identification, full biochemical identification may be...

Laboratory Diagnosis Isolation Procedures

Enterococci grow well on blood agar base media containing 5 animal blood and on many other media e.g., Mueller-Hinton, brain-heart infusion (BHI), dextrose phosphate, chocolate that are not selective for Gram-negative bacteria. Some strains of E. faecalis produce P-hemolysis on media containing rabbit, human or horse blood but not sheep blood. Bile-esculin azide (Enterococcosel agar) or other commercially available azide-containing media, Columbia colistin-nalidixic acid (CNA) agar, phenylethyl...

Mechanisms Of Resistance To Antimicrobial Agents

The presence of tolerance and or resistance to different classes of antibiotics is one of the typical characteristics of enterococci. Antimicrobial resistance among enterococci may be divided into two types intrinsic (or inherent) and acquired (Table 4.3). Intrinsic resistance refers to naturally occurring, chromosomally encoded characteristics encountered in all or almost all of the strains of a particular species. Acquired resistance is caused by acquisition of new DNA or mutations in the...

Meningitis

Pneumococcal meningitis caused by penicillin-susceptible strains should ideally be treated with benzylpenicillin 1.2 g 4 hourly for 10-14 days. The preferred treatment for infection caused by strains in which penicillin MIC levels are > 0.25 mg L is ceftriaxone 2-4 g once daily. Penicillin is ineffective against these resistant strains because CSF concentrations are unlikely to exceed 2-10 of serum levels. The efficacy of third-generation cephalosporins in pneumococcal meningitis diminishes...

Neonatal Infections

Enterococci cause neonatal sepsis and or meningitis, and it was reported as the second most common isolate in a point prevalence study of nosocomial infections in neonatal ICUs in the United States (Sohn etal., 2001). Although this may occur in normal-term infants, low-birth-weight infants and premature infants with severe underlying conditions are a high-risk group for enterococcal infections (Das and Gray, 1998). Use of a central catheter, the time the central line was in place, GI surgery,...

Other Less Common Infections

Besides neonatal meningitis, enterococci have also been cited as a cause of shunt infections and meningitis in older children and adults (Durand etal., 1993). In most of these patients, invasive procedures of the central nervous system, underlying diseases, previous antibiotic therapy and even disseminated strongyloidiasis were the predisposing factors for infection. Enterococci have also been found, usually with other microorganisms, in diabetic foot infections, decubitus ulcers, burns and...

Pathogenesis And Virulence Factors Gas Pathogenesis

The status of GAS as one of the most versatile of human pathogens is reflected in the astonishing array of putative virulence determinants associated with this organism. Lack of space and the remit of this chapter permit only a cursory discussion of the extensive and ever-expanding Principles and Practice of Clinical Bacteriology Second Edition Editors Stephen H. Gillespie and Peter M. Hawkey 2006 John Wiley & Sons, Ltd Table 1.2 Putative virulence factors of group A streptococcus (GAS)

Pathogenicity

Streptococcus pneumoniae has a collection of characteristics that permit it to colonise a variety of niches. Most pneumococci are found in the nasopharynx, a location where transformation can readily take place. This location also provides a convenient niche from which invasive disease can occur, and a complex interplay of factors determines whether the colonising organisms go on to establish invasive Principles and Practice of Clinical Bacteriology Second Edition Editors Stephen H. Gillespie...

Physiology

Streptococcus pneumoniae is a facultative anaerobe. It is capnophilic, preferring atmospheres of 5-10 carbon dioxide. Pneumococci exhibit fermentative metabolism, utilising glucose via the hexose monophosphate pathway. Four characteristics are especially useful in laboratory identification. The organism is 2. inhibited by ethyl hydrocupreine (optochin) 3. bile soluble (bile salts activate autolytic activity, producing cell lysis)

Pneumonia

The incidence of pneumococci that are highly resistant to penicillin (MIC > 4 lg mL) in the United Kingdom remains low, and documented clinical failures among penicillin-resistant pneumococcal pneumonia treated with adequate doses of penicillin are rare. The optimal duration of therapy for pneumococcal pneumonia is uncertain. Most physicians now treat for 10-14 days. Amoxicillin is the preferred agent, at a dose of 0.5-1 g three times daily. Clarithromycin 500 mg twice daily or the newer...

Preface

Change is inevitable and nowhere more than in the world of bacteriology. Since the publication of the first edition of this book in 1997 the speed of change has accelerated. We have seen the publication of whole genome sequences of bacteria. The first example, Mycoplasma genitalium, was heralded as a breakthrough, but this was only the first in a flood of sequences. Now a wide range of human, animal and environmental bacterial species sequences are available. For many important organisms,...

R

BE, reaction on bile-aesculin medium. +, > 95 of strains are positive > 5 of strains are negative V, variable reaction R, resistant S, susceptible. aAbiotrophia and Granulicatella (formerly nutritionally variant streptococci strains) are weakly pyrrolidonyl arylamidase and leucine aminopeptidase production positive and grow in 6.5 NaCl broth. Some group A streptococci are pyrrolidonyl arylamidase positive. b Some P-haemolytic streptococci grow in 6.5 NaCl broth. c 5-10 of viridans...

Section Three Gramnegative Organisms 189

13 Moraxella catarrhalis and Kingella kingae 191 Dlawer A. A. Ala'Aldeen and David P. J. Turner Peter Hawkey and Eugenie Bergogne-Berezin Qiushui He, Jussi Mertsola and Matti K. Viljanen 20 Actinobacillus actinomycetemcomitans 273 James G. Olson, Franca R. Jones and Patrick J. Blair Christiane B b ar, Sabine Pereyre and C cile M. B b ar 25 Chlamydia spp. and Related Organisms 317 27 Identification of Enterobacteriaceae 341 28 Escherichia coli and Shigella spp. 347 Christopher L. Baylis, Charles...

Susceptibility Testing

Since enterococcal susceptibility to antimicrobial agents is unpredictable, the site of infection and or the significance of a particular isolate determines which antimicrobials should be included in susceptibility testing. Drugs to which enterococci are intrinsically resistant, such as cephalosporins, oxacillin, trimethoprim-sulfamethoxazole (TMP-SMX) (in vivo resistance), clindamycin and aminoglycosides (when used as monotherapy), should not be tested. On the other hand, susceptibility to...

Treatment Of S Aureus Disease Toxin Mediated Disease

Management of TSS often includes the need for a high-dependency setting. The presence of tampons should be determined and removed where appropriate, and possible sources of infection should be carefully considered in non-menstrual cases. Cultures should be taken for the isolation of S. aureus and the organism sent to a reference laboratory to determine TSST-1 production if the diagnosis is in doubt. Acute and convalescent sera should be taken and stored and tested for evidence of seroconversion...

Treatment Strategies

Antimicrobial Therapy for -Streptococcal Disease -Haemolytic streptococci have remained exquisitely sensitive to penicillin. It is normal to give 10 days of treatment with penicillin V to fully treat streptococcal pharyngitis and prevent RF, although there is some preliminary evidence to suggest that 5 days of azithromycin will suffice (Bisno etal. 2002). Up to 30 of streptococcal sore throats treated with penicillin may relapse, possibly because of the internalisation of bacteria into buccal...

V

+, most (> 90 ) strains positive , most (> 90 ) strains negative V, variable. Adapted from Facklam and Collins (1989) and Facklam, Carvalho and Teixeira (2002). a Occasional exceptions reported. group D antigen, and mannitol, inulin, arabinose and arginine tests are negative (Martinez-Murcia and Collins, 1991). The two recently recognized nonmotile pigmented species, E. pallens and E. gilvus, may be differentiated from other pigmented species because they fit into group I, and therefore,...

Peter M Hawkey

University of Birmingham, Birmingham, UK Copyright 2006 John Wiley & Sons Ltd, The Atrium, Southern Gate, Chichester, West Sussex PO19 8SQ, England Email (for orders and customer service enquiries) cs-books wiley.co.uk All Rights Reserved. No part of this publication may be reproduced, stored in a retrieval system or transmitted in any form or by any means, electronic, mechanical, photocopying, recording, scanning or otherwise, except under the terms of the Copyright, Designs and Patents Act...

Paap

S. sanguis strains expressing PAAP caused endocarditis with a more severe clinical course Rat model. No strong correlation between endocardial infectivity and platelet-aggregating activity Willcox et al. (1994), Kitada, Inoue and Kitano (1997) Resistance to host defence mechanisms

Antimicrobial Resistance

P-Haemolytic streptococci of Lancefield groups A, B, C and G remain exquisitely sensitive to penicillin and other P-lactams, but resistance to sulphonamides and tetracyclines has been recognised since the Second World War. Penicillin has, therefore, always been the drug of choice for most infections caused by P-haemolytic streptococci, but macrolide compounds, including erythromycin, clarithromycin, roxithromycin and azithromycin, have been good alternatives in penicillin-allergic patients. In...

Molecular Typing Systems

Among various methods used for molecular epidemiology studies, total plasmid content, plasmid DNA digestion patterns, amplified fragment length polymorphism, ribotyping and conventional as well as pulsed-field gel electrophoresis (PFGE) of chromosomal DNA have been used to evaluate nosocomial enterococcal infections. PFGE is considered the gold standard and performs better at identifying clonality, at least during prolonged outbreaks. It is reproducible and generally available. A pilot study...

Prevention And Control Pneumococcal Vaccines

There are two types of pneumococcal vaccines a 23-valent pneumococcal polysaccharide vaccine (PPV) and a 7-valent pneumococcal conjugate vaccine (PCV). This is a polyvalent vaccine containing 25 lg of purified capsular polysaccharide from each of 23 capsular types of pneumococci that together account for about 96 of the pneumococcal isolates causing serious infection in Great Britain (World Health Organization, 1999). Most healthy adults develop a good antibody response to a single dose of the...

Cell Morphology and Cultural Characteristics

Light Microscopy and Staining Reactions Gram-stained cells of staphylococci are uniformly Gram positive in young (18-24 h) cultures and appear spherical with an average diameter of 0.5-1.5 lm on light microscopy. Cells divide in more than one plane to form irregular clusters. This is the commonest appearance but is not absolute. The possibility of S. aureus should not be discounted when organisms are seen as singles, pairs or other configurations, particularly when being observed on direct...

References

Angeletti, S., Lorino, G., Gherardi, G. etal. (2001) Routine molecular identification of enterococci by gene-specific PCR and 16S ribosomal DNA sequencing. J Clin Microbiol 39, 794-797. Arduino, R. C., Jacques-Palaz, K., Murray, B. E. and Rakita, R. M. (1994) Resistance of Enterococcus faecium to neutrophil-mediated phagocytosis. Infect Immun 62, 5587-5594. Arthur, M. and Courvalin, P. (1993) Genetics and mechanisms of glycopeptide resistance in enterococci. Antimicrob Agents Chemother 37,...

HLR Strains

HLR to either streptomycin or gentamicin abolishes the bactericidal synergism usually seen when these drugs are combined with cell-wall-active antibiotics. HLR to gentamicin predicts lack of synergistic killing with all other generally available aminoglycosides, except streptomycin. For this reason, all high-level gentamicin-resistant strains should be screened for high-level streptomycin resistance. Because the normally present chromosomally encoded aminoglycoside-modifying enzyme AAC(6') of...

List of Contributors

Ala'Aldeen Molecular Bacteriology and Immunology Group, Division of Microbiology, University Hospital, Nottingham NG7 2UH, UK Indran Balakrishnan Department of Medical Microbiology, Royal Free Hospital, Pond Street, London NW3 2QG, UK Christopher L. Baylis Campden & Chorleywood Food Research Association (CCFRA), Chipping Campden, Gloucestershire GL55 6LD, UK C cile M. B b ar Laboratoire de Bact riologie, Universit Victor Segalen Bordeaux 2, 146 rue L o Saignat, 33076 Bordeaux,...

Pandas

PANDAS, paediatric autoimmune disorders associated with streptococcal infections, overlap with chorea and tic disorders. For reviews on Sydenham's chorea and PANDAS, see Snider and Swedo (2003), Simckes and Spitzer (1995) and Shulman and Ayoub (2002). For reviews on guttate psoriasis, see Valdimarsson et al. (1995). For reviews on Kawasaki disease, see Curtis et al. (1995). Table 1.7 Revised Jones Criteria for diagnosing acute rheumatic fever (Adapted from American Heart Association 1992)...

Staphylococcus aureus Typing in the Clinical and Research Setting

Typing techniques performed in diagnostic or reference laboratories for clinical purposes usually aim to examine one of a limited number of situations. A cluster of S. aureus cases in a single ward or unit may be investigated to define whether strains are the same (indicating an outbreak) or different. This may be extended to tracking of the spread of strains between units or hospitals and to defining the relatedness of strains giving rise to outbreaks in more than one location. This type of...

Cellular And Secreted Components Cellular and Secreted Components

The cell membrane is a typical lipid-protein bilayer composed mainly of phospholipids and proteins. The cytochromes and menaquinones bound to cell membranes are important components of the electron transport system. Proteins isolated from the membranes of S. aureus include several penicillin-binding proteins (PBPs), which catalyse terminal reactions of peptidoglycan biosynthesis (Hartman and Tomasz 1984). Iron-regulated cell-membrane proteins are expressed under iron limitation (Domingue,...

Description Of The Organism Microscopic and Colonial Appearance

Draughtsman Appearance Pneumococci

Streptococcus pneumoniae is a small (0.5-1.0 lm diameter) lanceolate Gram-positive coccus (Figure 3.1). It replicates in chains in liquid media but forms pairs joined along the horizontal axis on solid media. Pneumococci grow better in the presence of a source of catalase and form small (0.5-2 mm diameter) colonies that are dome-shaped initially but collapse centrally owing to autolysis after longer incubation, producing the classic draughtsman shape. Pneumococci breakdown haemoglobin by...

Species Identification

Enterococcus faecalis accounts for more than 80 of the clinical isolates, followed by E. faecium and then by other enterococcal species e.g. E. gallinarum, E. avium, E. casseliflavus and E. raffmosus , although in settings with a high rate of VRE an increased proportion of E. faecium strains is usually found. Some other species are encountered less often Enterococcus mundtii, Enterococcus durans and Entero-coccus hirae , and some are mainly isolated from non-human sources Enterococcus...

Invasive Disease

Invasive disease includes bacteraemia, endocarditis, bone and joint infection and deep-site abscesses. One or more investigations may be required to delineate the extent of disease. Collections of pus should be drained where technically possible. Infected joints should be washed out by an orthopaedic surgeon in theatre to reduce joint damage and concomitant poor function. Temporary prosthetic material such as intravenous devices should be removed without delay. Infection caused by...

Genetic Exchange Antimicrobial Resistance of S aureus

The most significant events in the history of S. aureus antibiotic resistance are the emergence of resistance to penicillin which is now almost ubiquitous , the emergence of and epidemic rise in methicillin resistance, the recognition of strains with intermediate resistance to vancomycin and the recent emergence of S. aureus that is fully resistant to vancomycin. The mechanisms of resistance to other antimicrobial agents are summarized in Table 5.3. Penicillin-resistant S. aureus strains...

Bacteremia

Enterococcal bacteremia without endocarditis is a much more common event than endocarditis. The source of the bacteremia in the absence of endocarditis is often the urinary tract, the biliary tract, intra-abdominal or pelvic collections, intravascular catheters or wound infections, situations in which the finding of polymicrobial bacteremia is not uncommon Maki and Agger, 1988 . The features of enterococcal bacteremia that are associated with endocarditis include community-onset, the presence...

Intrinsic Resistance

Inherent resistance characteristics include resistance to semisynthetic penicillinase-resistant penicillins e.g., methicillin , cephalosporins, monobactams, quinupristin-dalfopristin E. faecalis , low levels of aminoglycosides and clindamycin and TMP-SMX in vivo and only moderate susceptibility to most fluoroquinolones. Vancomycin resistance in E. gallinarum and E. casseliflavus is also intrinsic and is discussed in the Glycopeptide Resistance section. Relative intrinsic resistance of...

Pathogenicity Virulence Factors in Enterococci

It was recognized early on that enterococci were less virulent than staphylococci, pneumococci and group A streptococci and were even called facultative parasites. The introduction and widespread use of antibiotics, many of which had no or poor activity against enterococci i.e. cephalosporins , was soon followed by an increase in the incidence of enterococcal infections. However, there were many reports of infections before the antibiotic era, which illustrates that these organisms are able to...