Aetiological diagnosis of brain abscesses and spinal infections: application of broad range bacterial polymerase chain reaction analysis

European society of Clinical Microbiology and Infectious Diseases guidelines on diagnosis and treatment of brain abscess in children and adults

SCOPE

These European Society of Clinical Microbiology and Infectious Diseases guidelines are intended for clinicians involved in diagnosis and treatment of brain abscess in children and adults.

METHODS

Key questions were developed, and a systematic review was carried out of all studies published since 1 January 1996, using the search terms 'brain abscess' OR 'cerebral abscess' as Mesh terms or text in electronic databases of PubMed, Embase, and the Cochrane registry. The search was updated on 29 September 2022. Exclusion criteria were a sample size <10 patients or publication in non-English language. Extracted data was summarized as narrative reviews and tables. Meta-analysis was carried out using a random effects model and heterogeneity was examined by I2 tests as well as funnel and Galbraith plots. Risk of bias was assessed using Risk Of Bias in Non-randomised Studies - of Interventions (ROBINS-I) (observational studies) and Quality Assessment of Diagnostic Accuracy Studies 2 (QUADAS-2) (diagnostic studies). The Grading of Recommendations Assessment, Development and Evaluation approach was applied to classify strength of recommendations (strong or conditional) and quality of evidence (high, moderate, low, or very low).

QUESTIONS ADDRESSED BY THE GUIDELINES AND RECOMMENDATIONS

Magnetic resonance imaging is recommended for diagnosis of brain abscess (strong and high). Antimicrobials may be withheld until aspiration or excision of brain abscess in patients without severe disease if neurosurgery can be carried out within reasonable time, preferably within 24 hours (conditional and low). Molecular-based diagnostics are recommended, if available, in patients with negative cultures (conditional and moderate). Aspiration or excision of brain abscess is recommended whenever feasible, except for cases with toxoplasmosis (strong and low). Recommended empirical antimicrobial treatment for community-acquired brain abscess in immuno-competent individuals is a 3rd-generation cephalosporin and metronidazole (strong and moderate) with the addition of trimethoprim-sulfamethoxazole and voriconazole in patients with severe immuno-compromise (conditional and low). Recommended empirical treatment of post-neurosurgical brain abscess is a carbapenem combined with vancomycin or linezolid (conditional and low). The recommended duration of antimicrobial treatment is 6-8 weeks (conditional and low). No recommendation is offered for early transition to oral antimicrobials because of a lack of data, and oral consolidation treatment after ≥6 weeks of intravenous antimicrobials is not routinely recommended (conditional and very low). Adjunctive glucocorticoid treatment is recommended for treatment of severe symptoms because of perifocal oedema or impending herniation (strong and low). Primary prophylaxis with antiepileptics is not recommended (conditional and very low). Research needs are addressed.

An immunocompetent patient with culture-negative multiple brain abscesses caused by Fusobacterium nucleatum

The diagnosis and treatment of brain abscesses have advanced due to the utilization of modern microbiological and neurosurgical methods. Here we present a 49-year-old female patient presented with headache and neurological symptoms. Initial evaluation revealed multiple ring-enhanced brain lesions and a lung cavitary lesion initially suspected to represent a malignant process. Stereotactic aspiration provided the diagnosis of brain abscesses but yielded negative cultures. 16S ribosomal RNA analysis enabled the identification of Fusobacterium nucleatum. For ten weeks, the patient was treated with ceftriaxone and metronidazole. A marked clinical and radiological improvement was noted. Brain abscess is a severe intracranial infectious process with significant morbidity and mortality. Microbiological analysis is challenging due to the location of the infection, the broad spectrum of causative agents, and the low yield of cultures. Fusobacterium nucleatum is an anaerobic bacteria with a tendency to abscess formation and is isolated from 2% of brain abscesses. The utilization of 16S RNA analysis improves microbiological identification rates in brain abscesses, as in other infectious entities, enabling better pathogen characterization and more suitable treatment.

Meningitis in a Chinese adult patient caused by Mycoplasma hominis: a rare infection and literature review

Background

Mycoplasma hominis, a well known cause of neonatal infection, has been reported as a pathogen in urogenital infections in adults; however, central nervous system (CNS) infections are rare. We report here the first case of M. hominis meningitis in China, post neurosurgical treatment for an intracerebral haemorrhage in a 71-year-old male.

Case presentation

We describe a 71-year-old man who developed M. hominis meningitis after neurosurgical treatment and was successfully treated with combined azithromycin and minocycline therapy of 2 weeks duration, despite delayed treatment because the Gram stain of cerebrospinal fluid (CSF) yielded no visible organisms. The diagnosis required 16S rDNA sequencing analysis of the cultured isolate from CSF. Literature review of M. hominis CNS infections yielded 19 cases (13 instances of brain abscess, 3 of meningitis, 1 spinal cord abscess and 1 subdural empyema each). Delay in diagnosis and initial treatment failure was evident in all cases. With appropriate microbiological testing, antibiotic therapy (ranging from 5 days to 12 weeks) and often, multiple surgical interventions, almost all the patients improved immediately.

Conclusions

Both our patient findings and the literature review, highlighted the pathogenic potential of M. hominis together with the challenges prompted by rare infectious diseases in particular for developing countries laboratories with limited diagnostic resources.

Electronic supplementary material

The online version of this article (doi:10.1186/s12879-016-1885-4) contains supplementary material, which is available to authorized users.

Cellular Microbiology of Mycoplasma canis

Mycoplasma canis can infect many mammalian hosts but is best known as a commensal or opportunistic pathogen of dogs. The unexpected presence of M. canis in brains of dogs with idiopathic meningoencephalitis prompted new in vitro studies to help fill the void of basic knowledge about the organism's candidate virulence factors, the host responses that it elicits, and its potential roles in pathogenesis. Secretion of reactive oxygen species and sialidase varied quantitatively (P < 0.01) among strains of M. canis isolated from canine brain tissue or mucosal surfaces. All strains colonized the surface of canine MDCK epithelial and DH82 histiocyte cells and murine C8-D1A astrocytes. Transit through MDCK and DH82 cells was demonstrated by gentamicin protection assays and three-dimensional immunofluorescence imaging. Strains further varied (P < 0.01) in the extents to which they influenced the secretion of tumor necrosis factor alpha (TNF-α) and the neuroendocrine regulatory peptide endothelin-1 by DH82 cells. Inoculation with M. canis also decreased major histocompatibility complex class II (MHC-II) antigen expression by DH82 cells (P < 0.01), while secretion of gamma interferon (IFN-γ), interleukin-6 (IL-6), interleukin-10 (IL-10), and complement factor H was unaffected. The basis for differences in the responses elicited by these strains was not obvious in their genome sequences. No acute cytopathic effects on any homogeneous cell line, or consistent patterns of M. canis polyvalent antigen distribution in canine meningoencephalitis case brain tissues, were apparent. Thus, while it is not likely a primary neuropathogen, M. canis has the capacity to influence meningoencephalitis through complex interactions within the multicellular and neurochemical in vivo milieu.

[Pyogenic brain abscesses in adults]

Pyogenic brain abscesses (BA) are rare and their diagnosis may be difficult because of the absence of specific clinical or biological signs. However, the use of diffusion-weighted brain MRI sequences has modified the management of BA, as they are highly sensitive and specific to differentiate pyogenic brain abscesses from necrotic tumors, which are the most frequent differential diagnosis in case of ring-enhancing lesions on CT scan. This new tool allows for a rapid diagnosis and should be followed by a CT-guided aspiration of BA. This safe procedure should be performed if possible before starting antibiotics in order to optimize microbiological diagnosis. Recent epidemiological changes include an increase in the numbers of immunocompromised patients and a decrease in the traditional causes of BA (direct inoculation, ear nose and throat infections, etc.). In consequence, a wider range of bacterial species may be involved, making it all the more necessary to obtain a microbiological diagnosis. Many uncertainties remain in terms of the duration of antibiotic treatment, the optimal radiological follow-up and the place for associated treatments such as corticosteroids and anticonvulsive therapy. BA remain severe infections with high mortality and morbidity rates; the factor most regularly associated with a poor prognosis is the patients neurological status at diagnosis.

Infektionen

In diesem Kapitel werden zunächst die für die Neurointensivmedizin wesentlichen bakteriellen Infektionen (Meningitis, spinale und Hirnabszesse, Spondylodiszitis, septisch-embolische Herdenzephalitis) abgehandelt, die trotz gezielt eingesetzter Antibiotika und neurochirurgischer Therapieoptionen noch mit einer erheblichen Morbidität und Mortalität behaftet sind. Besonderheiten wie neurovaskuläre Komplikationen, die Tuberkulose des Nervensystems, Neuroborreliose, Neurosyphilis und opportunistische Infektionen bei Immunsuppressionszuständen finden hierbei besondere Berücksichtigung. Der zweite Teil dieses Kapitels behandelt akute und chronische Virusinfektionen des ZNS sowie in einem gesonderten Abschnitt die HIVInfektion und HIV-assoziierte Krankheitsbilder sowie Parasitosen und Pilzinfektionen, die in Industrieländern seit Einführung der HAART bei HIV zwar eher seltener, aber mit zunehmender Globalisierung auch in unseren Breiten immer noch anzutreffen sind.

Spinal infections due to Eikenella corrodens: case report and literature review

Spinal infections with Eikenella corrodens are rare. We report a unique case of infection caused by E. corrodens diagnosed more than two years after cervical surgery. All other published cases of spinal infections caused by E. corrodens were searched. Characteristics of this bacterium, its challenging diagnosis and therapy are discussed.

Mycoplasma hominis brain abscess presenting after a head trauma: a case report

Introduction

Mycoplasma hominis brain abscess is a rare occurrence, and treatment is not well defined. The mechanism by which M. hominis infects sites outside the genitourinary tract, including the central nervous system, is unclear.

Case presentation

We report the case of a 40-year-old Somali man who sustained a traumatic brain injury that required initial neurosurgical hematoma evacuation and that subsequently was complicated by a hospital-acquired M. hominis brain abscess. Our patient was successfully treated with neurosurgical debridement and an antibiotic course of intravenous doxycycline.

Conclusions

Head trauma or neurosurgical procedures or both might be a predisposing factor for this type of infection.

Infektionen

Trotz Weiterentwicklung moderner Antibiotika in den letzten Jahren sind die Letalitätszahlen der bakteriellen (eitrigen) Meningitis weiterhin hoch; Überlebende haben häufig neurologische Residuen. Die ungünstigen klinischen Verläufe der bakteriellen Meningitis sind meist Folge intrakranieller Komplikationen, wie z. B. eines generalisierten Hirnödems, einer zerebrovaskulären arteriellen oder venösen Beteiligung oder eines Hydrozephalus.

Metagenomic analysis of brain abscesses identifies specific bacterial associations

BACKGROUND

The bacterial flora involved in brain abscess is often complex. In a previous study, using a metagenomic approach based on 16S ribosomal DNA (rDNA) amplification, we demonstrated that the diversity of the microbial flora involved in these infections was underestimated.

METHODS

We performed a 16S rDNA-based metagenomic analysis of cerebral abscesses from patients diagnosed from 2006 through 2010. All bacteria present in brain abscess specimens were identified, in view of the clinical and epidemiological characteristics of the patients.

RESULTS

Fifty-one patients were included in our study. By detecting polymicrobial infections in 19 patients, our strategy was significantly more discriminatory and enabled the identification of a greater number of bacterial taxa than did culture and conventional 16S rDNA polymerase chain reaction (PCR) and sequencing, respectively (P < 10(-2)). Data mining discriminated 2 distinct bacterial populations in brain abscess from dental and sinusal origin. In addition, of the 80 detected bacterial species, we identified 44 bacteria that had never been found in brain abscess specimens, including 22 uncultured bacteria. These uncultured agents mostly originated from the buccal or sinusal floras (P < 10(-2)) and were found in polymicrobial specimens (P < 10(-2)).

CONCLUSIONS

Cloning and sequencing of PCR-amplified 16S rDNA is a highly valuable method to identify bacterial agents of brain abscesses.

Mycoplasma salivarium isolated from brain abscesses

We report two cases of cerebral abscesses with polymicrobial aetiology including Mycoplasma salivarium. In both cases, Mycoplasma was found incidentally, suggesting that a broader aetiological spectrum could be found in brain abscesses by use of molecular techniques targeting fastidious pathogens.

Clostridium sordellii brain abscess diagnosed by 16S rRNA gene sequencing

Clostridium sordellii is usually associated with skin and soft tissue infections. We describe the first case to our knowledge of a Clostridium sordellii-associated brain abscess, diagnosed by 16S rRNA gene sequencing, expanding the microbiological spectrum of brain abscesses, with emphasis on the role of 16S rRNA gene PCR in their etiologic diagnosis.

Detection of a mixed infection in a culture-negative brain abscess by broad-spectrum bacterial 16S rRNA gene PCR

We describe the identification of two bacterial pathogens from a culture-negative brain abscess by the use of broad-spectrum 16S rRNA gene PCR. Simultaneous detection of Fusobacterium nucleatum and Porphyromonas endodontalis was possible due to a 24-bp length difference of their partially amplified 16S rRNA genes, which allowed separation by high-resolution polyacrylamide gel electrophoresis.

Primary ventriculitis caused byStreptococcus intermedius

Streptococcus intermedius is increasingly being recognised as an aetiological agent in central nervous system infections. Primary ventriculitis caused by this organism has not been reported so far. We present a case of primary ventriculitis, which resulted in adhesions and multiloculated hydrocephalus, necessitating numerous surgical procedures to control it. No predisposing factor(s) could be identified. Although the organism could not be cultured from CSF, as he was already on antibiotic treatment, it could, however, be identified by 16S rDNA polymerase chain reaction on the CSF sample. It appears important to recognise this condition and to treat it aggressively to prevent complications such as adhesions and multiloculated hydrocephalus.

Optimization of bacterial diagnosis yield after needle aspiration in immunocompetent adults with brain abscesses

OBJECTIVE

Brain abscesses (BA) are life threatening, even in immunocompetent patients, in part because microbiological diagnosis is often lacking and management is empirical. Recent epidemiological changes make it all the more important to have a precise microbiological diagnosis. Our purpose was to evaluate the efficacy of a strategy aimed at obtaining a microbiological diagnosis in immunocompetent patients presenting with suspected BAs.

METHODS

We conducted a cohort study including all consecutive patients suspected of having BAs according to clinical, biological, and radiological findings. Severely immunocompromised patients were excluded. Aspiration was performed free-hand in patients with superficial abscesses (<1 cm depth from the cortical surface) and under stereotactic guidance in patients with deep-seated abscesses. Microbiological diagnosis was optimized, using the best aerobic and anaerobic growth conditions, blood culture bottles inoculated in the operating room, and molecular biology techniques if necessary. Antibiotic treatment was adapted according to the findings.

RESULTS

Twenty-six patients were suspected of having BAs during the study period. Twenty-four patients benefited from aspiration (stereotactic puncture in 3 cases), which was safe, confirmed the diagnosis of BAs, and yielded microbiological diagnosis in all cases, even in those patients who had previously received antibiotics (n = 8; 33%). In 10 patients (42%), microbiological results led to a different choice in antibiotic therapy than the recommended empirical regimen.

CONCLUSION

Microbiological diagnosis can be obtained in all cases of BA. This is achieved by the conjunction of rapid needle aspiration and the optimization of microbiological diagnosis resulting from fast management of the surgical specimen, good anaerobic culture conditions, and the use of blood culture bottles and molecular biology techniques when appropriate. Moreover, it is of clinical and therapeutic interest when BAs are suspected in immunocompetent patients.

Broad-range PCR as a supplement to culture for detection of bacterial pathogens in patients with a clinically diagnosed spinal infection

We aimed to evaluate broad-range PCR and subsequent sequencing compared to conventional culture in the diagnosis of spinal infection. The method was a prospective study of all patients admitted to Aarhus University Hospital for surgery during a 12-months period with a clinically diagnosed infection of the spine. Samples from patients undergoing surgery for non-infectious causes (malignancy etc.) were included as control group. Specimens were submitted to conventional culture and molecular investigation with 16S rRNA gene amplification and sequence analysis. 38 patients were included in the study (clinically diagnosed spinal infections=18; non-infectious diseases=20). The specificity was excellent for both culture and PCR (95% and 100%, respectively). A true culture positive result was obtained in 50% of patients (9/18) and 61% was positive (11/18) by broad-range PCR. When combined, culture and PCR allowed for a microbiological diagnosis in 72% of patients (13/18). A positive culture was found only in patients treated < or =7 d compared to < or =16 d for PCR. However, PCR and culture result were equally negatively affected by duration of treatment. The combination of culture and broad-range PCR substantially adds to the number of microbiological diagnoses obtained, and improves the clinician's opportunity to tailor therapy to individual patients.

Validation criteria for nucleic acid amplification techniques for bacterial infections

Nucleic acid techniques (NATs), such as species-specific and universal polymerase chain reactions (PCRs), are finding ever wider use in the diagnosis of bacterial infection. However, although universal PCR assays, in particular, approach a type of modern Petri dish, they have a number of limitations which restrict their applicability. The sensitivity of universal PCR is lower than that of many species-specific PCRs, and the contamination of samples and PCR reagents with irrelevant DNA from various sources remains a problem. Thus, NATs in general and universal PCR assays in particular require careful validation to be of value for the diagnosis of infection. Validation includes sampling, DNA extraction/isolation, template amplification and visualisation of the results. Furthermore, it implies the establishment of measures of asepsis, the inclusion of positive and negative controls, techniques to optimise the release of DNA from bacterial cells, adequate repetition of the amplification reaction, and routine testing of reagent negative and inhibition controls. Finally, it entails the comparison of results obtained by NATs with those obtained by conventional microbiological methods and matching with clinical evidence of infection. Validation of NATs in clinical diagnosis remains an ongoing challenge. Because of these limitations, NATs can only serve as adjunct tools for the diagnosis of infection in selected cases; they cannot replace conventional culturing techniques.

Atypical mycobacterial spondylitis in HIV-negative patients identified by genotyping

Non-tuberculous mycobacterial infections pose a significant diagnostic and therapeutic challenge. We report two cases of such infection of the spine in HIV-negative patients who presented with deformity and neurological deficit. The histopathological features in both specimens were diagnostic of tuberculosis. The isolates were identified as Mycobacterium intracellulare and M. fortuitum by genotyping (MicroSeq 16S rDNA Full Gene assay) and as M. tuberculosis and a mycobacterium other than tuberculosis, respectively, by culture. There is a growing need for molecular diagnostic tools that can differentiate accurately between M. tuberculosis and atypical mycobacteria, especially in regions of the developing world which are experiencing an increase in non-tuberculous mycobacterial infections.

[Multiple intracerebral lesions. Identification of the causative agent by 16S rDNA-PCR]

Molecular biological methods such as polymerase chain reaction (PCR) enable microbiologists to detect bacteria even if antibiotic treatment has already been started. Based on this case report of a 39-year-old man with multiple intracerebral lesions, we describe a PCR method called 16S rDNA-PCR which can be used to identify panbacterial DNA by focussing on the universal gene sequences for the bacterial 16S part of the ribosome.

Undiagnosed patent foramen ovale presenting as a cryptogenic brain abscess: case report and review of the literature

A 43-year-old man with no significant medical history but poor oral hygiene presented with fever and new-onset tonic-clonic seizures secondary to a left parieto-occipital brain abscess defined by computed tomography, magnetic resonance imaging, and surgical evacuation. A comprehensive workup looking for a source of infection was unremarkable including computed tomography of the chest, abdomen, and pelvis; blood cultures; and a tagged white blood cell scan. A transesophageal echocardiogram bubble study revealed the presence of a patent foramen ovale (PFO) but no other abnormalities. Culture of the material obtained at surgery revealed flora commonly found in the oropharynx that responded to antibiotic therapy. A review of the literature revealed three other cases in which a brain abscess from flora commonly found in the oropharynx was associated with a PFO. We hypothesize that the underlying mechanism is a significant bacterial load from poor dentition that enters the arterial circulation through a PFO and forms the nidus for a brain abscess. Surgical evacuation is the preferred method for diagnosis and initial treatment. If a brain abscess is identified without any adjacent source of infection, a recent head trauma, or a neurosurgical procedure, then a transesophageal echocardiogram is indicated to exclude a PFO. If a PFO is found, then hematogenous spread of flora normally found in the oropharynx through a right to left shunt should be suspected. Surgical evacuation followed by intravenous antibiotics specific to the identified organisms is warranted. Once the infection is eliminated, anatomic closure of the PFO with good oral hygiene practices may be the best course of action for preventing recurrences.

Biofilm-related infections of cerebrospinal fluid shunts

Cerebrospinal fluid (CSF) shunts carry a high risk of complications. Infections represent a major cause of shunt failure. Diagnosis and therapy of such infections are complicated by the formation of bacterial biofilms attached to shunt surfaces. This study correlated the pathophysiology and clinical course of biofilm infections with microscopical findings on the respective shunts. Surface irregularities, an important risk-factor for shunt colonisation with bacteria, were found to increase over time because of silicone degradation. Scanning electron-microscopy (SEM) documented residual biological material (dead biofilm), which can further promote extant bacterial adhesion, on newly manufactured shunts. Clinical course and SEM both documented bacterial dissemination against CSF flow and the monodirectional valve. In all cases, biofilms grew on both the inner and outer surfaces of the shunts. Microscopy and conventional culture detected all bacterial shunt infections. Analyses of 16S rDNA sequences using conserved primers identified bacteria in only one of three cases, probably because of previous formalin fixation of the samples.

Analysis of microbial etiology and mortality in patients with brain abscess

OBJECTIVES

Despite the technological advancements in diagnostic and neurosurgical procedures, brain abscess continues to remain a potentially fatal central nervous system infection. In a prospective study we determined the predisposing factors and the microbiological profile of brain abscess. We also analyzed the mortality in patients with the type of infections identified.

METHODS

Over a period of 8 years (1997-2004), aspirated pus from 118 patients with brain abscess was directly inoculated into BACTEC PLUS+ aerobic and BACTEC PLUS+ anaerobic media immediately after collection and subcultured on solid media as appropriate. Predisposing factors, if any, were recorded in all patients. Mortality of patients during hospital stay was correlated with the type of infections identified.

RESULTS

Predisposing factors were identified in 94 (79.7%) patients, otogenic infection being the most common (37/118; 31.4%). Microorganisms were demonstrated in 96 (81.4%) patients, by culture in 89 (75.4%) patients and by Gram stain in 7 (5.9%) additional cases. A total of 105 organisms were isolated - 67 (63.8%) aerobes, 32 (30.5%) anaerobes, 5 (4.8%) mycobacteria and 1 (0.9%) fungus. Viridans streptococci (23.8%), Staphylococcus aureus (14.3%), Bacteroides fragilis group/species and Peptostreptococcus species (10.5% each) were the common isolates. Overall mortality was 14.4%; patients with Gram-negative infections had higher mortality than Gram-positive infections (6/20; 30% vs. 6/63; 9.5%; P=0.02).

CONCLUSIONS

Culture of pus immediately after aspiration in an automated system yields good results. Gram stain coupled with culture can guide the neurosurgeons better to treat their patients more rationally. Patients with Gram-negative infections need special attention in terms of management because of high mortality rate.

Aetiological diagnosis of infective endocarditis by direct amplification of rRNA genes from surgically removed valve tissue. An 11-year experience in a Finnish teaching hospital

BACKGROUND/AIMS

The aetiology of infective endocarditis (IE) can be determined directly from surgically removed valve tissue using broad-range bacterial rDNA polymerase chain reaction (PCR) followed by sequencing. We sought to assess the value of this methodology in a routine clinical setting.

METHODS

Broad-range PCR with primers targeting conserved bacterial rDNA sequences was applied to directly analyse valve samples from 56 patients operated on for diagnosed or suspected IE. Identification of the aetiological agent was performed by partial DNA sequencing of the 16S and 23S rDNA genes.

RESULTS

The final diagnosis was definite IE in 36 patients and possible IE in 2 patients, while the diagnosis of IE was rejected in 18 patients. PCR analysis from removed valve tissue was positive in 25 patients with IE. Molecular identification was consistent with the blood culture finding in 20 of these patients. The PCR approach was the only method to yield the aetiological diagnosis in additional 4 patients (2 Staphylococcus species, 1 Streptococcus bovis, 1 Bartonella quintana), all of whom had received antimicrobials before blood cultures were taken. The mean duration of preoperative antimicrobial treatment for the patients with PCR-positive valves was 19.6 (range 1-58) days.

CONCLUSIONS

Bacterial DNA may persist during treatment in infected valves for long periods. The PCR method is especially useful when the causative agent of IE is fastidious or when the specimen is taken during antimicrobial treatment.

Polymerase Chain Reaction for the Rapid Detection of Cerebrospinal Fluid Shunt or Ventriculostomy Infections

OBJECTIVE:

Infection after cerebrospinal fluid (CSF) shunts or ventriculostomies is a common complication associated with significant morbidity and mortality. Polymerase chain reaction (PCR) is a powerful molecular technique that allows rapid and precise amplification of bacterial deoxyribonucleic acid (DNA) and has proven a powerful tool in the detection of a wide variety of clinically important infectious diseases. We analyzed specimens of CSF derived from ventriculoperitoneal shunts or external ventricular drains by using both conventional cultures and PCR and report herein our preliminary results.

METHODS:

We selected 86 CSF samples from adult patients who underwent either shunt tap or routine surveillance cultures of their ventriculostomy. These specimens were chosen from a larger group of 300 specimens that were routinely collected (many serially) in our clinical practice. They were chosen because clinical suspicion of infection was increased because of either patient signs and symptoms (fever, stiff neck, lethargy, worsening neurological examination) or preliminary laboratory analysis of CSF data (increased white blood cell count, increased protein level, decreased glucose). We considered this subgroup optimal to efficiently initiate our investigation of the correlation of PCR and culture results. CSF was increased by using standard culture techniques and by using PCR. Samples of CSF that were to undergo PCR had DNA extracted, purified, and amplified for 16S rRNA using primers 16S-Forward and 16S-Reverse of conserved sequence regions of all bacteria. DNA was PCR-amplified for 30 cycles. One microliter of the first PCR product was subjected to nested PCR using primers specific for gram-positive and gram-negative bacteria. Samples were also subjected to PCR amplification for specific detection of Propionibacterium acnes, Staphylococcus aureus, and methicillin-resistant Staphylococcus aureus using specific primers for 16S rRNA Propionibacterium, nuclease gene of Staphylococcus, and Mec gene of methicillin-resistant Staphylococcus aureus.

RESULTS:

For 18 of 86 specimens (21%), both the culture and PCR were positive. For 30 of 86 specimens (35%), both the PCR and culture results were negative. For 42 of 86 specimens (49%), cultures were negative and PCR was positive. There were no positive culture results with negative PCR results. Most negative culture/positive PCR cases occurred after prolonged intravenous antibiotics. Of the 56 PCR-positive specimens, 30 were positive for Propionibacterium acnes, whereas 40 were positive for Staphylococcus aureus. Of the Staphylococcus aureus-positive specimens, two were positive for methicillin resistant-Staphylococcus aureus. Among the 56 PCR-positive specimens, 30 were positive for both Propionibacterium acnes and Staphylococcus aureus; gram-negative organisms were not detected by any method in these specimens.

CONCLUSION:

These preliminary data suggest that PCR is a highly sensitive, rapid, and potentially promising modality for the detection and treatment of CSF shunt ventriculostomy infection.

Disseminated Pyogenic Mycoplasma pneumoniae Infection in a Renal Transplant Recipient, Detected by Broad-Range Polymerase Chain Reaction

Although extrapulmonary manifestations of Mycoplasma pneumoniae infection are generally immune-mediated, disseminated infections occasionally occur. We describe a renal transplant recipient who developed disseminated pyogenic M. pneumoniae infection that was detected by broad-range polymerase chain reaction and that manifested by prosthetic arterial graft infection, psoas abscess, and septic arthritis.

Development of real-time PCR for detection of Mycoplasma hominis

BACKGROUND

Mycoplasma hominis is associated with pelvic inflammatory disease, bacterial vaginosis, post partum fever, sepsis and infections of the central nervous system often leading to serious conditions. Association with development of female infertility has also been suggested, but different publications present different results. We developed a sensitive and fast diagnostic real-time PCR to test clinical samples from women undergoing laparoscopic examination before fertility treatment. To develop a test for the detection and quantification of M. hominis we selected a housekeeping gene, glyceraldehyde-3-phosphate dehydrogenase (gap), as a target.

RESULTS

Real-time PCR was optimized to detect 10 copies of M. hominis PG21 genomic DNA. A fluorescence signal was measured for all 20 other M. hominis isolates, and melting curves analysis showed variations in the melting temperature in agreement with sequence variation in the region of the probes. There was no amplification of other mycoplasmal DNA and human DNA. Eighty-three patient cervical swab samples from infertile women were cultured for M. hominis in the BEa medium. Two of the samples (2.4%) were positive after 48 hours of incubation. The real-time PCR detected the same two samples positive, and the DNA concentrations in the clinical specimens were calculated to 37.000 copies/ml and 88.500 copies/ml, respectively.

CONCLUSION

The results demonstrate that real-time PCR may prove to be a rapid alternative to the traditional cultivation method. Information on bacterial load in genital swabs can be obtained. The assay allowed detection of M. hominis in a closed system reducing the risk of contamination by amplicon carry-over.