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1.  Bartonella henselae Endocarditis in Laos – ‘The Unsought Will Go Undetected’ 
Both endocarditis and Bartonella infections are neglected public health problems, especially in rural Asia. Bartonella endocarditis has been described from wealthier countries in Asia, Japan, Korea, Thailand and India but there are no reports from poorer countries, such as the Lao PDR (Laos), probably because people have neglected to look.
Methodology/Principal Findings
We conducted a retrospective (2006–2012), and subsequent prospective study (2012–2013), at Mahosot Hospital, Vientiane, Laos, through liaison between the microbiology laboratory and the wards. Patients aged >1 year admitted with definite or possible endocarditis according to modified Duke criteria were included. In view of the strong suspicion of infective endocarditis, acute and convalescent sera from 30 patients with culture negative endocarditis were tested for antibodies to Brucella melitensis, Mycoplasma pneumoniae, Bartonella quintana, B. henselae, Coxiella burnetii and Legionella pneumophila. Western blot analysis using Bartonella species antigens enabled us to describe the first two Lao patients with known Bartonella henselae endocarditis.
We argue that it is likely that Bartonella endocarditis is neglected and more widespread than appreciated, as there are few laboratories in Asia able to make the diagnosis. Considering the high prevalence of rheumatic heart disease in Asia, there is remarkably little evidence on the bacterial etiology of endocarditis. Most evidence is derived from wealthy countries and investigation of the aetiology and optimal management of endocarditis in low income countries has been neglected. Interest in Bartonella as neglected pathogens is emerging, and improved methods for the rapid diagnosis of Bartonella endocarditis are needed, as it is likely that proven Bartonella endocarditis can be treated with simpler and less expensive regimens than “conventional” endocarditis and multicenter trials to optimize treatment are required. More understanding is needed on the risk factors for Bartonella endocarditis and the importance of vectors and vector control.
Author Summary
Infection of heart valves (endocarditis) with bacteria is an important condition, especially afflicting those with rheumatic heart disease, and has a high mortality if untreated. Most of the evidence for optimal antibiotic and surgical management comes from wealthy countries. There are no published data from poorer countries in SE Asia despite a high burden of rheumatic heart disease. We investigated the bacterial infections of heart valves in the Lao PDR (Laos) through heart ultrasound scans and analysis of patients' blood. We provide evidence of infection with the poorly understood bacteria Bartonella henselae (the cause of cat scratch disease) in two patients from Laos. We argue that it is likely that Bartonella endocarditis is more widespread than appreciated, as there are few laboratories in Asia able to make the diagnosis. This is important as it is likely that proven Bartonella endocarditis can be treated with simpler and less expensive regimens than “conventional” endocarditis. There have been great advances in the wealthy world in the diagnosis and treatment of endocarditis but these have not been assessed or implemented in poorer countries. More evidence on the causes and optimal management of endocarditis in low income countries is needed.
PMCID: PMC4263471  PMID: 25503777
2.  Investigations on the efficacy of routinely used phenotypic methods compared to genotypic approaches for the identification of staphylococcal species isolated from companion animals in Irish veterinary hospitals 
Irish Veterinary Journal  2013;66(1):7.
Identification of Staphylococci to species level in veterinary microbiology is important to inform therapeutic intervention and management. We report on the efficacy of three routinely used commercial phenotypic methods for staphylococcal species identification, namely API Staph 32 (bioMérieux), RapID (Remel) and Staph-Zym (Rosco Diagnostica) compared to genotyping as a reference method to identify 52 staphylococcal clinical isolates (23 coagulase positive; 29 coagulase negative) from companion animals in Irish veterinary hospitals.
Genotyping of a 412 bp fragment of the staphylococcal tuf gene and coagulase testing were carried out on all 52 veterinary samples along with 7 reference strains. In addition, genotyping of the staphylococcal rpoB gene, as well as PCR-RFLP of the pta gene, were performed to definitively identify members of the Staphylococcus intermedius group (SIG). The API Staph 32 correctly identified all S. aureus isolates (11/11), 83% (10/12) of the SIG species, and 66% (19/29) of the coagulase negative species. RapID and Staph-Zym correctly identified 61% (14/23) and 0% (0/23) respectively of the coagulase-positives, and 10% (3/29) and 3% (1/29) respectively of the coagulase-negative species.
Commercially available phenotypic species identification tests are inadequate for the correct identification of both coagulase negative and coagulase positive staphylococcal species from companion animals. Genotyping using the tuf gene sequence is superior to phenotyping for identification of staphylococcal species of animal origin. However, use of PCR-RFLP of pta gene or rpoB sequencing is recommended as a confirmatory method for discriminating between SIG isolates.
PMCID: PMC3649918  PMID: 23635328
Companion animals; Staphylococci species identification; Genotyping; tuf; rpoB
3.  Health Care–Associated Native Valve Endocarditis in Patients with no History of Injection Drug Use: Current Importance of Non-Nosocomial Acquisition 
Annals of internal medicine  2009;150(9):586-594.
The clinical profile and outcome of nosocomial and non-nosocomial health care–associated native valve endocarditis are not well defined.
To describe the prevalence, clinical characteristics, and outcomes of nosocomial and non-nosocomial health care–associated native valve endocarditis.
Prospective observational study.
61 hospitals in 28 countries.
Patients with definite native valve endocarditis and no history of injection drug use who were enrolled in the International Collaboration on Endocarditis–Prospective Cohort Study from June 2000 to August 2005.
Characteristics of nosocomial and non-nosocomial health care–associated native valve endocarditis cases were described and compared with those cases acquired in the community.
Health care–associated native valve endocarditis was present in 557 (34%) of 1622 patients with native valve endocarditis and no history of injection drug use (nosocomial native valve endocarditis 303 patients [54%]; non-nosocomial health care–associated native valve endocarditis 254 patients [46%]). Staphylococcus aureus was the most common cause of health care-associated native valve endocarditis (nosocomial native valve endocarditis, 47%; non-nosocomial health care–associated native valve endocarditis, 42%; p=0.3), with a notable proportion of methicillin-resistant S. aureus (nosocomial native valve endocarditis, 57%; non-nosocomial health care–associated native valve endocarditis, 41%; p=0.014). Patients with health care–associated native valve endocarditis had lower rates of cardiac surgery (41% health care–associated native valve endocarditis vs 51% community-acquired native valve endocarditis, p<0.001) and higher in-hospital mortality rates than patients with community-acquired native valve endocarditis (25% health care–associated native valve endocarditis vs. 13% community-acquired native valve endocarditis vs., p<0.001). Multivariable analysis confirmed a higher mortality associated with health care–associated native valve endocarditis (incidence risk ratio=1.20 (CI 95%, 1.03–1.61).
This study involves tertiary hospitals with cardiac surgery programs. The results may not be generalized to patient populations receiving care in other types of facility.
More than one-third of all cases of native valve endocarditis in non-drug users involve contact with health care. S. aureus is the leading cause of health care–associated native valve endocarditis. Non-nosocomial health care–associated native valve endocarditis is common, especially in the US. Patients with health care-associated and community-acquired native valve endocarditis differ in their presentation, microbiology, and outcome. By contrast, patients with nosocomial and non-nosocomial healthcare-associated endocarditis are similar.
PMCID: PMC3625649  PMID: 19414837
infective endocarditis; healthcare-associated endocarditis; nosocomial endocarditis; non-nosocomial healthcare-associated endocarditis; community-acquired endocarditis; Staphylococcal aureus endocarditis; MRSA endocarditis; Coagulase-negative staphylococcal endocarditis; Surgery; Outcome
4.  Clinical comparative study on the activity of cefamandole in the treatment of serious staphylococcal infections caused by methicillin-susceptible and methicillin-resistant strains. 
Ninety-two microbiologically documented staphylococcal infections were treated with cefamandole in an open comparative study on the clinical efficacy of this cephalosporin in the therapy of infections caused by both methicillin-susceptible and methicillin-resistant Staphylococcus aureus and coagulase-negative Staphylococcus spp. The majority of the episodes (86 of 92) were treated with cefamandole alone, and six were treated with cefamandole in association with other antibiotics. In the evaluable S. aureus infections, 34 of 46 (73.9%) due to methicillin-susceptible strains and 12 of 16 (75%) due to methicillin-resistant strains responded to therapy. In particular, among the patients infected by methicillin-susceptible S. aureus 6 of 9 cases of septicemia, 0 of 2 cases of endocarditis, 2 of 2 cases of pneumonia, 2 of 3 osteoarticular infections, 8 of 12 cases of peritonitis in patients with chronic renal failure in continuous ambulatory peritoneal dialysis (CAPD), 13 of 15 skin-soft tissue infections, and 3 of 3 urinary tract infections responded to therapy. Among those due to methicillin-resistant strains, cure was achieved in 2 of 4 cases of septicemia, 0 of 1 case of endocarditis, 9 of 10 skin-soft tissue infections, and 1 of 1 urinary tract infection. In the evaluable infections caused by coagulase-negative staphylococci, 9 of 11 (81.8%) due to methicillin-susceptible and 15 of 17 (88.2%) due to methicillin-resistant strains responded to therapy. In particular, among patients infected by methicillin-susceptible, coagulase-negative staphylococci, 4 of 4 cases of septicemia, 0 of 1 case of endocarditis, 1 of 1 case of pneumonia, 1 of 1 case of peritonitis in CAPD, 2 of 3 infections of skin-soft tissue, and 1 of 1 urinary tract infection responded to therapy. Among patients infected by methicillin-resistant, coagulase-negative staphylococci were cured 5 of 6 cases os septicemia, 6 of 6 cases of peritonitis (in CAPD), 4 of 4 infections of skin-soft tissue, and 0 of 1 urinary tract infection.
PMCID: PMC284155  PMID: 3637066
5.  Ampicillin-sulbactam is effective in prevention and therapy of experimental endocarditis caused by beta-lactamase-producing coagulase-negative staphylococci. 
Optimal strategies for the prophylaxis and therapy of endocarditis caused by oxacillin-resistant, coagulase-negative staphylococci in patients with native or prosthetic valvular heart disease are not well defined. We compared the in vivo efficacies of ampicillin-sulbactam-based regimens with those of vancomycin-based oxacillin-resistant, beta-lactamase-producing coagulase-negative staphylococcal isolate (Staphylococcus haemolyticus SE220). Ampicillin-sulbactam (100 and 20 mg/kg of body weight, respectively, given intramuscularly in a two-dose regimen) was equivalent to vancomycin (30 mg/kg given intravenously in a two-dose regimen) in its prophylactic efficacy against the coagulase-negative staphylococcal strain (93 and 80%, respectively). The combination of ampicillin-sulbactam plus either rifampin or vancomycin did not enhance the prophylactic efficacy compared with that of ampicillin-sulbactam or vancomycin alone. In the therapy of established aortic valve endocarditis in rabbits caused by this same coagulase-negative staphylococcal strain, animals received 7-day ampicillin-sulbactam-based or vancomycin-based regimens with or without rifampin. All treatment regimens were effective at lowering intravegetation coagulase-negative staphylococcal densities and rendering vegetations culture negative compared with the coagulase-negative staphylococcal densities and vegetations of untreated controls, with ampicillin-sulbactam in combination with rifampin or vancomycin being the most active regimen. However, only the regimen of ampicillin-sulbactam in combination with vancomycin effectively prevented relapse of endocarditis posttherapy after a 5-day antibiotic-free period. For animals receiving rifampin-containing regimens, relapses of endocarditis were associated with the in vivo development of rifampin resistance among coagulase-negative staphylococcal isolates in the vegetation. Ampicillin-sulbactam was highly effective in the prevention of experimental endocarditis caused by a beta-lactamase-producing, oxacillin-resistant coagulase-negative staphylococcal strain. Ampicillin-sulbactam was also efficacious for the therapy of coagulase-negative staphylococcal endocarditis, especially when it was combined with vancomycin to prevent posttherapeutic relapses.
PMCID: PMC163064  PMID: 8787887
6.  Staphylococcus capitis endocarditis: two cases and review of the literature 
Heart  1999;82(3):e1.
Coagulase negative staphylococci are the principal cause of prosthetic valve endocarditis but are a rare cause of native valve infections. However, the incidence of native valve endocarditis is increasing. Staphylococcus capitis is a coagulase negative staphylococcus with the capacity to cause endocarditis on native heart valves. Two cases of native valve endocarditis caused by S capitis are presented; both in patients with aortic valve disease. The patients were cured with prolonged intravenous vancomycin and rifampicin and did not need surgery during the acute phase of the illness. Five of the six previously described cases of endocarditis caused by this organism occurred on native valves and responded to medical treatment alone.

Keywords: Staphylococcus capitis; endocarditis; valvar disease; coagulase negative staphylococci
PMCID: PMC1729175  PMID: 10455099
7.  Adherence of coagulase-negative staphylococci to plastic tissue culture plates: a quantitative model for the adherence of staphylococci to medical devices. 
Journal of Clinical Microbiology  1985;22(6):996-1006.
The adherence of coagulase-negative staphylococci to smooth surfaces was assayed by measuring the optical densities of stained bacterial films adherent to the floors of plastic tissue culture plates. The optical densities correlated with the weight of the adherent bacterial film (r = 0.906; P less than 0.01). The measurements also agreed with visual assessments of bacterial adherence to culture tubes, microtiter plates, and tissue culture plates. Selected clinical strains were passed through a mouse model for foreign body infections and a rat model for catheter-induced endocarditis. The adherence measurements of animal passed strains remained the same as those of the laboratory-maintained parent strain. Spectrophotometric classification of coagulase-negative staphylococci into nonadherent and adherent categories according to these measurements had a sensitivity, specificity, and accuracy of 90.6, 80.8, and 88.4%, respectively. We examined a previously described collection of 127 strains of coagulase-negative staphylococci isolated from an outbreak of intravascular catheter-associated sepsis; strains associated with sepsis were more adherent than blood culture contaminants and cutaneous strains (P less than 0.001). We also examined a collection of 84 strains isolated from pediatric patients with cerebrospinal fluid (CSF) shunts; once again, pathogenic strains were more adherent than were CSF contaminants (P less than 0.01). Finally, we measured the adherence of seven endocarditis strains. As opposed to strains associated with intravascular catheters and CSF shunts, endocarditis strains were less adherent than were saprophytic strains of coagulase-negative staphylococci. The optical densities of bacterial films adherent to plastic tissue culture plates serve as a quantitative model for the study of the adherence of coagulase-negative staphylococci to medical devices, a process which may be important in the pathogenesis of foreign body infections.
PMCID: PMC271866  PMID: 3905855
8.  Native Valve Endocarditis Caused by Coagulase Negative Staphylococci; an Appeal to Start Outpatient Antimicrobial Therapy: An Unusual Case Report 
Oman Medical Journal  2011;26(4):269-270.
Coagulase negative staphylococci (CNS) were a rare cause of native valve endocarditis. However, they are emerging as an important cause of native valve endocarditis (NVE) in both community and healthcare settings. We describe a 64 yrs. old male who developed mitral valve endocarditis caused by coagulase negative staphylococci. There were no predisposing conditions or underlying cardiac disease that could have been the risk factor for the development of native valve infection. The patient had good recovery after six weeks of treatment with anti-staphylococcal antibiotics.
PMCID: PMC3191720  PMID: 22043433
Coagulase negative staphylococcus; CoNS; Native valve endocarditis; NVE; Outpatient antimicrobial therapy; OPAT
9.  Clinical and microbiological profiles of infective endocarditis in a tertiary hospital in Aseer region, Saudi Arabia 
We aimed to evaluate demographic data, underlying cardiac abnormalities, clinical profile, microbiological features, treatments and complications of infective endocarditis (IE) in a tertiary hospital in Aseer region, Saudi Arabia.
A retrospective study of all cases with the diagnosis of definite endocarditis according to modified Duke Criteria admitted to ACH between May 2002 and April 2007. Data were reviewed on demographic and clinical data, underlying cardiac disease, microbiological findings, treatments and complications of IE.
The study included 44 patients (28 males and 16 females; mean age 31.1 ± 16 years; range 13–65 years). Infective endocarditis developed on a native valve in 31 (70.5%), a mechanical prosthetic valve in 10 (22.7%), mitral valve prolapse in 2 (4.5%) and ventricular septal defect in 1 (2.3%). Rheumatic heart disease in 31 cases (70.5%) was the most common preexisting valvular abnormality in native valve endocarditis. The mitral valve was the most commonly affected valve 28 (63.6%). Fever occurred in 40 (90.9%) of the cases. Electrocardiography was abnormal in 34 cases (77.3%). Trans-thoracic and/or trans-esophageal echocardiography showed a vegetation in 22 (50%). Staphylococci in 10 cases (22.7%) and Streptococci in 8 cases (18%) were the most common causative agents and cultures were negative in 20 cases (45.5%). Twenty-two patients (50%) underwent surgical treatment. Congestive heart failure occurred in 16 (36.4%) cases, atrial fibrillation in 6 (13.6%) cases, and cerebrovascular accidents in 4 (9%) cases.
Our data reflects the clinical and microbiological profiles of IE in a tertiary hospital in Aseer region, Saudi Arabia.
PMCID: PMC3727542  PMID: 23960650
Endocarditis; Echocardiography; Microbiologic; Culture negative; Valvular heart disease; Prosthetic valve; Saudi Arabia
10.  Staphylococcus lugdunensis endocarditis 
Postgraduate Medical Journal  2001;77(906):259-260.
A case of Staphylococcus lugdunensis endocarditis is presented with low back pain suggesting a secondary bone focus of infection. An umbilical skin lesion may have been an additional embolic phenomenon. The case highlights the aggressive nature of S lugdenensis endocarditis compared with other coagulase negative staphylococci and its association with native heart valves. In addition the importance of full identification of coagulase negative staphylococci isolated from patient samples in a case of suspected S lugdenensis infection is emphasised. Antibiotic treatment may be insufficient alone in the treatment of S lugdenensis endocarditis and early recourse to surgical intervention and valve replacement should therefore be considered.

Keywords: Staphylococcus lugdunensis; endocarditis; coagulase negative staphylococci
PMCID: PMC1741967  PMID: 11264492
11.  Vertebral osteomyelitis and native valve endocarditis due to Staphylococcus simulans: a case report 
Staphylococcus simulans is a common animal pathogen that occasionally can colonize human skin. Unlike other coagulase-negative staphylococci, S. simulans tends to cause more severe infections that resemble those caused by S. aureus. We present a case of vertebral osteomyelitis and endocarditis due to S. simulans. To the best of our knowledge, this is the first report of vertebral osteomyelitis associated with native valve endocarditis rather than orthopedic surgery.
Case presentation
A 46-year-old male butcher was admitted to the hospital with a 4-week history of high fever with profound sweating. He reported weakness in his legs and low back pain that compromised his walking ability. Blood cultures yielded Gram-positive cocci on Gram stain. These cocci were identified to the species level as S. simulans, a coagulase-negative staphylococcus. The patient was treated with antibiotics, which were discontinued after 6 months.
This case illustrates the importance of identifying coagulase-negative staphylococci to the species level. Accurate identification of S. simulans would further help investigations defining its pathogenic role in human infections.
PMCID: PMC2426703  PMID: 18510763
12.  Infective endocarditis in children: A 5 year experience from Al-Zahra Hospital, Isfahan, Iran 
Considering that there are no regional published data regarding the epidemiologic findings of infective endocarditis (IE) in children, in this study we reviewed the epidemiologic and clinical features and treatment and outcome of children diagnosed with IE at Al-Zahra hospital over a 5-year period.
Materials and Methods:
In this retrospective study, medical records of patients (<18 years old) admitted from March 2006 to March 2011 in Al-Zahra Hospital (Pediatrics Infectious or Cardiology Departments) reviewed. The medical files reviewed regarding demographic, clinical, diagnostic (laboratory, microbiological and echocardiographic details) and treatment and outcome details. Obtained data were recorded in a questionnaire. The diagnosis of IE was determined based on Duke criteria.
In this study, 17 patients fulfill the Duke criteria for definite or the possible IE. The most common causes of IE was non-cyanotic heart disease (ventricular septal defect and AS; 64.8%). From cyanotic hearth disease, Tetralogy of Fallot (TOF) was the most frequent causes (11.8%). In this study, 41% of patients with IE aged < 2 years and 70% aged < 6 years. In this study, 76.5% of patients had a history of congenital heart disease or cardiac surgery. Blood cultures were positive in 10 patients (58.8%). Coagulase-negative staphylococci (23.5%) and Staphylococcus aureus (11.7%) were the most common organisms that cause IE.
It seems that in order to provide a regional comprehensive guideline for appropriate management and prevention of IE related complications further advanced studies with larger sample size and evaluation is recommended.
PMCID: PMC4260283  PMID: 25538914
Congenital heart disease; infective endocarditis; pediatric
13.  From Clinical Microbiology to Infection Pathogenesis: How Daring To Be Different Works for Staphylococcus lugdunensis 
Clinical Microbiology Reviews  2008;21(1):111-133.
Staphylococcus lugdunensis has gained recognition as an atypically virulent pathogen with a unique microbiological and clinical profile. S. lugdunensis is coagulase negative due to the lack of production of secreted coagulase, but a membrane-bound form of the enzyme present in some isolates can result in misidentification of the organism as Staphylococcus aureus in the clinical microbiology laboratory. S. lugdunensis is a skin commensal and an infrequent pathogen compared to S. aureus and S. epidermidis, but clinically, infections caused by this organism resemble those caused by S. aureus rather than those caused by other coagulase-negative staphylococci. S. lugdunensis can cause acute and highly destructive cases of native valve endocarditis that often require surgical treatment in addition to antimicrobial therapy. Other types of S. lugdunensis infections include abscess and wound infection, urinary tract infection, and infection of intravascular catheters and other implanted medical devices. S. lugdunensis is generally susceptible to antimicrobial agents and shares CLSI antimicrobial susceptibility breakpoints with S. aureus. Virulence factors contributing to this organism's heightened pathogenicity remain largely unknown. Those characterized to date suggest that the organism has the ability to bind to and interact with host cells and to form biofilms on host tissues or prosthetic surfaces.
PMCID: PMC2223846  PMID: 18202439
14.  Clinical experience with daptomycin in Europe: the first 2.5 years 
To describe the patient populations and infections being treated with daptomycin, as well as the efficacy and safety outcomes.
Patients and methods
Data from the European Cubicin Outcomes Registry and Experience (EU-CORESM), retrospectively collected at 118 institutions between January 2006 and August 2008, were analysed.
Daptomycin treatment was documented in 1127 patients with diverse infections, including complicated skin and soft tissue infections (33%), bacteraemia (22%), endocarditis (12%) and osteomyelitis (6%). It was used empirically, before microbiological results became available, in 53% of patients. Staphylococcus aureus was the most common pathogen (34%), with 52% of isolates resistant to methicillin; coagulase-negative staphylococci and enterococci were also frequent, with 22% of Enterococcus faecium isolates resistant to vancomycin. Daptomycin was used as first-line therapy in 302 (27%) patients. When used second line, the most common reasons for discontinuation of previous antibiotic were treatment failure and toxicity or intolerance. The use of concomitant antibiotics was reported in 65% of patients. Most frequent doses were 6 mg/kg (47%) and 4 mg/kg (32%). The median duration of daptomycin therapy was 10 days (range 1–246 days) in the inpatient setting and 13 days (range 2–189 days) in the outpatient setting. The overall clinical success rate was 79%, with a clinical failure rate of <10% for all infection types. Low failure rates were observed in first- and second-line therapy (6% and 8%, respectively). Daptomycin demonstrated a favourable safety and tolerability profile regardless of treatment duration.
Daptomycin has a relevant role in the treatment of Gram-positive infections.
PMCID: PMC3058564  PMID: 21393205
cyclic lipopeptide; Gram-positive infections; registry
15.  Characterization of methicillin-susceptible and -resistant staphylococci in the clinical setting: a multicentre study in Nigeria 
BMC Infectious Diseases  2012;12:286.
The staphylococci are implicated in a variety of human infections; however, many clinical microbiology laboratories in Nigeria do not identify staphylococci (in particular coagulase negative staphylococci - CNS) to the species level. Moreover, data from multi-centre assessment on antibiotic resistance and epidemiology of the staphylococci are not available in Nigeria. This study investigated 91 non-duplicate staphylococcal isolates obtained from the microbiology laboratories of eight hospitals in Nigeria during the period January to April 2010.
Identification and antibiotic susceptibility testing was performed using the VITEK 2 system, detection of resistance genes by PCR, and molecular characterization was determined by SCCmec typing, spa and multilocus sequence typing (MLST).
All the isolates were susceptible to mupirocin, tigecycline, vancomycin and linezolid, but 72.5% of CNS and 82.3% of Staphylococcus aureus were resistant to cotrimoxazole, while multiresistance was observed in 37 of the 40 CNS isolates. Untypeable SCCmec types (ccrC/Class A mec and ccr-negative/Class C2 mec gene complex) in two methicillin-resistant S. aureus (MRSA) were identified. Additionally, ccr-negative/Class A mec and ccr type 4/Class C2 mec gene complex was detected in one isolate each of S. sciuri and S. haemolyticus, respectively. The S. aureus isolates were classified into 21 spa types including two new types (t8987, t9008) among the methicillin-susceptible S. aureus (MSSA) isolates. Two (CC8-SCCmecnon-typeable and CC88-SCCmec IV) and four (CC8-SCCmec III/IV/V; CC30-SCCmec II/III; CC88-SCCmec IV; and ST152-SCCmecnon-typeable) MRSA clones were identified in Maiduguri (North-East Nigeria) and South-West Nigeria, respectively. The proportion of Panton-Valentine leukocidin (PVL)-positive MSSA was high (44.4%) and 56.3% of these strains were associated with sequence type (ST) 152.
The identification of multiresistant mecA positive S. haemolyticus and S. sciuri from clinical samples indicates that characterization of CNS is important in providing information on their diversity and importance in Nigeria. There is the need to develop new SCCmec classification methods for non-typeable methicillin-resistant staphylococci, and to curtail the spread and establishment of the S. aureus ST152 clone in Nigeria. The study presents the first report of a PVL-positive ST152-SCCmecnontypeable MRSA and SCCmec typing of methicillin-resistant CNS in Nigeria.
PMCID: PMC3529121  PMID: 23121720
Coagulase negative staphylococci; Staphylococcus aureus; Multiresistance; mecA gene; Staphylococcus haemolyticus; Staphylococcus sciuri; Panton Valentine Leukocidin; SCCmec typing; ST152; Nigeria
16.  Comparative Molecular and Microbiologic Diagnosis of Bacterial Endocarditis 
Emerging Infectious Diseases  2003;9(12):1543-1547.
Sequencing of 16S rDNA, and of sodAint and rpoBint in some cases, was applied to DNA from heart valves of 46 patients (36 with definite and 10 with possible endocarditis). Sequence-based identifications were compared with those obtained with conventional methods. Among the 36 definite cases, 30 had positive blood cultures and 6 had negative cultures. Among the 30 positive cases, sequencing of 16S rDNA permitted identification of species (18), genus (8), or neither (4); sodAint and rpoBint sequencing was necessary for species identification in 8 cases. Species identifications were identical in only 61.5%, when conventional techniques and DNA sequencing were used. In five of the six blood culture–negative endocarditis cases, sequencing identified Bartonella quintana (3), B. henselae (1), and Streptococcus gallolyticus (1). Our results demonstrate a clear benefit of molecular identification, particularly in cases of blood culture–negative endocarditis and of possible endocarditis, to confirm or invalidate the diagnosis. Moreover, in 19.4% of the definite cases, the improvement in species identification by sequencing led to improved patient management.
PMCID: PMC3034331  PMID: 14720393
Endocarditis; negative blood culture; molecular diagnosis; PCR; 16S rDNA; rpoB and sodA genes
17.  Molecular diagnosis of culture negative infective endocarditis: clinical validation in a group of surgically treated patients 
Heart  2003;89(3):263-268.
Objective: To assess the clinical validity of polymerase chain reaction (PCR) based molecular methods in the microbiological diagnosis of culture negative infective endocarditis in a group of surgically treated patients.
Design: Retrospective case–control study.
Setting: Reference cardiovascular surgical centre.
Patients and samples: 15 culture negative patients with infective endocarditis classified according to Duke criteria, with 17 heart valve samples; 13 age and sex matched control patients without infective endocarditis, with 13 valve samples.
Interventions: Medical records were reviewed and clinical, demographic, and microbiological data collected, including results of molecular detection of bacteria and fungi from valve samples. The clinical validity of molecular diagnosis was assessed, along with the sensitivity and speed of the systems.
Results: In the study group, 14 patients were PCR positive (93%). Organisms detected were streptococci (3), staphylococci (2), enterobacter (1), Tropheryma whippelii (1), Borrelia burgdorferi (1), Candida albicans (1), and Aspergillus species (2). Three cases were positive on universal bacterial detection but the pathogen could not be identified because of contaminating background. One case was negative. All but two positive cases showed clinical correlations. These two cases had no symptoms of infective endocarditis but there was agreement with the surgical findings. All control cases were PCR negative. Results were available within eight hours, and if sequencing was necessary, within 48 hours.
Conclusions: PCR based molecular detection of pathogens in valve samples from surgically treated culture negative infective endocarditis patients is fast, sensitive, and reliable. The technology, combined with thorough validation and clinical interpretation, may be a promising tool for routine testing of infective endocarditis.
PMCID: PMC1767592  PMID: 12591825
infective endocarditis; molecular biology; polymerase chain reaction
18.  Comparison of Real-Time PCR and Conventional Biochemical Methods for Identification of Staphylococcus lugdunensis▿  
Journal of Clinical Microbiology  2009;47(11):3472-3477.
Staphylococcus lugdunensis is an aggressive, virulent member of the coagulase-negative staphylococci (CoNS) that is responsible for severe, rapidly progressive skin and soft tissue infections and native valve endocarditis. To facilitate prompt identification and appropriate therapy, we describe here a rapid and robust multiplex real-time PCR assay that is able to definitively distinguish S. lugdunensis from other staphylococci. Using melting curve analysis, the assay also identifies Staphylococcus aureus and CoNS other than S. lugdunensis and determines MecA-dependent resistance to methicillin (meticillin). When applied to a panel of well-characterized staphylococcal reference strains, as well as 165 clinical isolates previously identified by conventional methods, the assay was both sensitive and specific for S. lugdunensis, correctly identifying the reference strain and all 47 S. lugdunensis isolates without inappropriate amplification of other staphylococci. Furthermore, rapid biochemical identification using the WEE-TAB system to detect ornithine decarboxylase activity was found to be unsuitable as an alternative to PCR identification, displaying just 31% sensitivity and 77% specificity when tested on a subset (90 isolates) of the clinical strains. We therefore propose that this simple, accurate PCR approach will allow for the routine and timely identification of S. lugdunensis in the clinical microbiology laboratory.
PMCID: PMC2772579  PMID: 19741081
19.  Microbiological aspects of peritonitis associated with continuous ambulatory peritoneal dialysis. 
Clinical Microbiology Reviews  1992;5(1):36-48.
The process of continuous ambulatory peritoneal dialysis has provided a useful, relatively inexpensive, and safe alternative for patients with end-stage renal disease. Infectious peritonitis, however, has limited a more widespread acceptance of this technique. The definition of peritonitis in this patient population is not universally accepted and does not always include the laboratory support of a positive culture (or Gram stain). In part, the omission of clinical microbiological findings stems from the lack of sensitivity of earlier microbiological efforts. Peritonitis results from decreased host phagocytic efficiency with depressed phagocytosis and bactericidal capacity of peritoneal macrophages. During episodes of peritonitis, fluid movement is reversed, away from the lymphatics and peritoneal membrane and toward the cavity. As a result, bloodstream infections are rare. Most peritonitis episodes are caused by bacteria. Coagulase-negative staphylococci are the most frequently isolated organisms, usually originating from the skin flora, but a wide array of microbial species have been documented as agents of peritonitis. Clinical microbiology laboratories need to be cognizant of the diverse agents so that appropriate primary media can be used. The quantity of dialysate fluid that is prepared for culture is critical and should constitute at least 10 ml. The sensitivity of the cultural approach depends on the volume of dialysate, its pretreatment (lysis or centrifugation), the media used, and the mode of incubation. The low concentration of microorganisms in dialysate fluids accounts for negative Gram stain results. Prevention of infection in continuous ambulatory peritoneal dialysis patients is associated with the socioeconomic status of the patient, advances in equipment (catheter) technology, and, probably least important, the application of prophylactic antimicrobial agents.
PMCID: PMC358222  PMID: 1735094
20.  Adherence of bacteria to heart valves in vitro. 
Journal of Clinical Investigation  1975;56(6):1364-1370.
The abilities of 14 strains of aerobic gram-positive cocci and gram-negative bacilli to adhere in vitro to human or canine aortic valve leaflets were compared. 2-mm sections of excised valve leaflets were obtained by punch biopsy and were incubated under standardized conditions in suspensions of bacteria. Valve sections were subsequently washed and homogenized, and quantitative techniques were used to determine the proportions of bacteria from the initial suspensions that had adhered to the valve sections. Comparable results were obtained when these adherence ratios were determined by two independent methods based either on measurements of bacterial viability or of radioactivity in 51Cr-labeled bacteria. For each bacterial strain, the adherence ratio was constant over a wide range of concentrations of bacteria in the incubation medium. Strains of enterococci, viridans streptococci, coagulase-positive and coagulase-negative staphylococci and Pseudomonas aeruginosa (adherence ratios 0.003-0.017) were found to adhere more readily to valve sections than strains of Escherichia coli and Klebsiella pneumoniae (adherence ratios 0.00002-0.00004). The organisms that most frequently cause bacterial endocarditis were found to adhere best to heart valves in vitro, suggesting that the ability to adhere to valvular endothelium may be an important or essential charcteristic of bacteria that cause endocarditis in man.
PMCID: PMC333113  PMID: 811687
21.  Health-care associated infections rates, length of stay, and bacterial resistance in an intensive care unit of Morocco: Findings of the International Nosocomial Infection Control Consortium (INICC) 
Most studies related to healthcare-associated infection (HAI) were conducted in the developed countries. We sought to determine healthcare-associated infection rates, microbiological profile, bacterial resistance, length of stay (LOS), and extra mortality in one ICU of a hospital member of the International Infection Control Consortium (INICC) in Morocco.
We conducted prospective surveillance from 11/2004 to 4/2008 of HAI and determined monthly rates of central vascular catheter-associated bloodstream infection (CVC-BSI), catheter-associated urinary tract infection (CAUTI) and ventilator-associated pneumonia (VAP). CDC-NNIS definitions were applied. device-utilization rates were calculated by dividing the total number of device-days by the total number of patient-days. Rates of VAP, CVC-BSI, and CAUTI per 1000 Device-days were calculated by dividing the total number of HAI by the total number of specific Device-days and multiplying the result by 1000.
1,731 patients hospitalized for 11,297 days acquired 251 HAIs, an overall rate of 14.5%, and 22.22 HAIs per 1,000 ICU-days. The central venous catheter-related bloodstream infections (CVC-BSI) rate found was 15.7 per 1000 catheter-days; the ventilator-associated pneumonia (VAP) rate found was 43.2 per 1,000 ventilator-days; and the catheter-associated urinary tract infections (CAUTI) rate found was 11.7 per 1,000 catheter-days.
Overall 25.5% of all Staphylococcus aureus HAIs were caused by methicillin-resistant strains, 78.3% of Coagulase-negative-staphylococci were methicillin resistant as well. 75.0% of Klebsiella were resistant to ceftriaxone and 69.5% to ceftazidime. 31.9% of E. Coli were resistant to ceftriaxone and 21.7% to ceftazidime. 68.4% of Enterobacter sp were resistant to ceftriaxone, 55.6% to ceftazidime, and 10% to imipenem; 35.6% of Pseudomonas sp were resistant to ceftazidime and 13.5% to imipenem.
LOS of patients was 5.1 days for those without HAI, 9.0 days for those with CVC-BSI, 10.6 days for those with VAP, and 13.7 days for those with CAUTI.
Extra mortality was 56.7% (RR, 3.28; P =< 0.001) for VAP, 75.1% (RR, 4.02; P = 0.0027) for CVC-BSI, and 18.7% (RR, 1.75; P = 0.0218) for CAUTI.
HAI rates, LOS, mortality, and bacterial resistance were high. Even if data may not reflect accurately the clinical setting of the country, programs including surveillance, infection control, and antibiotic policy are a priority in Morocco.
PMCID: PMC2765432  PMID: 19811636
22.  Value of Microimmunofluorescence for Diagnosis and Follow-up of Bartonella Endocarditis 
Bartonella endocarditis is a disease of emerging importance that causes serious complications and high rates of mortality. Due to the fastidious nature of Bartonella species and their high degrees of antibiotic susceptibility, cultures of clinical samples most often remain sterile and valvular biopsy specimens, the best specimens for PCR amplification, are seldom available. Therefore, serology appears to be the easiest diagnostic tool. In order to determine the best cutoff value for serology and its predictive values for the detection of Bartonella endocarditis, we studied 48 patients with culture- and/or PCR-confirmed Bartonella endocarditis. We also applied these serological criteria to 156 patients with blood culture-negative endocarditis. Furthermore, we compared the kinetics of the antibody responses to Bartonella spp. in order to estimate the value of serology for prediction of the occurrence of relapses. A titer of ≥1:800 for immunoglobulin G antibodies to either Bartonella henselae or B. quintana has a positive predictive value of 0.810 for the detection of chronic Bartonella infections in the general population and a value of 0.955 for the detection of Bartonella infections among patients with endocarditis. When this cutoff was applied to 156 patients with blood culture-negative endocarditis, we were able to diagnose Bartonella infections in an additional 45 patients with definite endocarditis for whom a positive Bartonella serology was the only evidence of infection. On follow-up, the kinetics of the decrease in antibody titers were significantly delayed in two patients with relapses. In conclusion, we recommend the determination of antibodies to both B. quintana and B. henselae and the use of a cutoff value of 1:800 for the diagnosis of Bartonella endocarditis. We propose that this criterion, which may also help with the detection of late relapses, be included as a major criterion in the Duke criteria for the diagnosis of infective endocarditis.
PMCID: PMC120030  PMID: 12093675
23.  Increase in native valve endocarditis caused by coagulase negative staphylococci: an Anglo-French clinical and microbiological study. 
British Heart Journal  1990;64(6):381-384.
Native valve endocarditis caused by coagulase negative staphylococci has become more common. A study of 35 cases showed that the infections were usually acquired in the community and occurred in men (mean age 51 years). A pre-existing cardiac abnormality (mitral leaflet prolapse in a third of patients) was detected in 26 (74%). The source of the organisms in the community acquired infections was assumed to be the skin, though lesions were seldom demonstrated; most hospital acquired infections resulted from intravenous devices. Community acquired organisms were usually sensitive to penicillin, whereas those acquired in hospital were often multiresistant. Most infections were caused by Staphylococcus epidermidis. The frequency of acute presentation (26%) and of major neurological abnormality (23%), together with the need for valve replacement (often emergency) (51%) and the mortality (36%) suggest that coagulase negative staphylococci can be virulent aggressive pathogens, mimicking Staphylococcus aureus.
PMCID: PMC1224815  PMID: 2271345
24.  Complete Genome Sequence of Staphylococcus lugdunensis Strain HKU09-01▿  
Journal of Bacteriology  2010;192(5):1471-1472.
Staphylococcus lugdunensis is a member of the coagulase-negative staphylococci and commonly found as part of the human skin flora. It is a significant cause of catheter-related bacteremia and also causes serious infections like native valve endocarditis in previously healthy individuals. We report the complete genome sequence of this medically important bacterium.
PMCID: PMC2820864  PMID: 20047907
25.  Daptomycin for methicillin-resistant Staphylococcus epidermidis native-valve endocarditis: a case report 
Coagulase-negative staphylococci (CoNS) have been increasing in importance as a cause of native valve endocarditis (NVE). Most cases of NVE caused by CoNS are attributable to Staphylococcus epidermidis. NVE caused by CoNS acquired in a nosocomial setting may differ from cases acquired in the community in several ways. It may be associated with hemodialysis, the presence of a long-term indwelling central catheter or pacemaker, or a recent invasive procedure; nosocomial cases may have a higher rate of methicillin resistance among CoNS isolates, and so be more likely to be treated with vancomycin. Unfortunately, NVE caused by methicillin-resistant CoNS has been associated with significantly higher rates of persistent bacteremia and in-hospital mortality than methicillin-susceptible isolates. The poor outcomes in these cases point to the need for alternative therapies with potent activity against methicillin-resistant CoNS. In our medical center, a 76-year-old man presented with native-valve endocarditis and positive blood cultures for methicillin-resistant Staphylococcus epidermidis (MRSE). During each of three 6-week courses of treatment with vancomycin, blood cultures were negative, but they once again became positive for MRSE when vancomycin was discontinued. The minimum inhibitory concentration of the MRSE isolates for vancomycin remained stable at 2 μg/mL. Eventually, treatment with daptomycin was initiated (500 mg [7 mg/kg]) 3 times/week for 6 weeks. Over the following year, no positive cultures for MRSE were detected.
PMCID: PMC2836277  PMID: 20167084

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