A decade surveillance study of Mycobacterium xenopi disease and antimicrobial susceptibility levels in a reference teaching hospital of northern Italy: HIV-associated versus non-HIV-associated infection

Treatment of spondylodiscitis

PURPOSE

Pyogenic infections of the spine are relatively rare with an incidence between 1:100,000 and 1:250,000 per year, but the incidence is increasing due to increases in average life-expectancy, risk factors, and medical comorbidities. The mean time in hospital varies from 30 to 57 days and the hospital mortality is reported to be 2-17%. This article presents the relevant literature and our experience of conservative and surgical treatment of pyogenic spondylodiscitis.

METHOD

We have performed a review of the relevant literature and report the results of our own research in the diagnosis and treatment of pyogenic spondylodiscitis. We present a sequential algorithm for identification of the pathogen with blood cultures, CT-guided biopsies and intraoperative tissue samples. Basic treatment principles and indications for surgery and our surgical strategies are discussed.

RESULTS

Recent efforts have been directed toward early mobilisation of patients using primary stable surgical techniques that lead to a further reduction of the mortality. Currently our hospital mortality in patients with spondylodiscitis is around 2%. With modern surgical and antibiotic treatment, a relapse of spondylodiscitis is unlikely to occur. In literature the relapse rate of 0-7% has been recorded. Overall the quality of life seems to be more favourable in patients following surgical treatment of spondylodiscitis.

CONCLUSION

With close clinical and radiological monitoring of patients with spondylodiscitis, conservative and surgical therapies have become more successful. When indicated, surgical stabilisation of the infected segments is mandatory for control of the disease and immediate mobilisation of the patients.

Profiling Mycobacterium xenopi with restriction fragment length polymorphism of insertion element IS1395

OBJECTIVES

The aim of the present study was to assess the usefulness of insertion element IS1395 for differentiation of Mycobacterium xenopi, an increasingly common opportunistic human pathogen.

METHODS

Fifty-two isolates obtained from 51 patients in Poland in 1996, 1997, and 1999, were analyzed by IS1395 restriction fragment length polymorphism (RFLP), and their susceptibilities to 11 anti-tuberculosis drugs were also determined.

RESULTS

IS1395-associated banding patterns of the isolates were not highly polymorphic; the RFLP patterns displayed several bands in common. Nevertheless, 44 of the 52 isolates were clearly distinguishable from each other. Only eight strains (15.4%) occurred in four clusters of two identical clones, one of which comprised two isolates obtained from one patient with a 12-month interval. The remaining six patients with clustered strains showed no apparent epidemiologic links with the other patients from the same cluster, and they were most likely infected by the same environmental source. No noticeable difference in RFLP pattern or IS1395 copy number between drug-sensitive and drug-resistant strains was shown. A high proportion (84.6%) of strains resistant to at least one drug was found, and 7.7% were resistant to more than three drugs.

CONCLUSIONS

The stability and utility of IS1395 for further detailed epidemiological investigations of M. xenopi was confirmed and extended.

Current treatment of atypical mycobacteriosis

BACKGROUND

Atypical mycobacteria are a heterogeneous group of organisms that are of increasing importance because of the growing number of infections they cause. This rising rate of infection is due mainly to the increase in the number of susceptible (and especially immunosuppressed) patients.

OBJECTIVE

To revise the currently used treatment schemes of the most commonly isolated atypical mycobacteria.

METHODS

Literature review using reference books and PubMed with specific keywords for each mycobacteria.

RESULTS/CONCLUSION

The first important step in the management of atypical mycobacteria is to recognize the true infections caused by these organisms. The treatment required varies according to species. Well-characterized combinations exist for most common isolates, with the use of first-line antituberculous drugs (isoniazid, rifampin, ethambutol), clarithromycin, aminoglycosides and/or quinolones for slowly growing species (Mycobacterium avium complex, Mycobacterium kansasii, Mycobacterium xenopi, Mycobacterium ulcerans, Mycobacterium marinum, Mycobacterium lentiflavum, Mycobacterium malmoense) and macrolides, quinolones, amikacin and other antibiotics for rapidly growing mycobacteria (Mycobacterium abscessus, Mycobacterium chelonae, Mycobacterium fortuitum). Surgical therapy is also important for some species (Mycobacterium ulcerans, Mycobacterium scrofulaceum) and for localized infections. The treatment of uncommon species is not well defined and is determined by the results of in vitro tests of individual strains. Because of the increasing number of resistant strains, new antibiotics need to be used for the treatment of these strains.

Spondylodiscitis caused by Mycobacterium xenopi

The infection with non-tuberculous mycobacterium correlates highly with immunodeficiency. Mycobacterium xenopi (M. xenopi) is most commonly isolated in the respiratory tract, as a cause of endogenous spondylodiscitis it occurs but rarely. Only seven such cases have been reported in literature. In this paper, we present the case of an about 28-year-old HIV-positive patient with a long history of back pain. MRI of the spinal column and Positron Emission Tomography with (18)F-fluorodeoxyglucose as a tracer (F18-FDG-PET) confirmed the suspected spondylodiscitis. After performing a CT-controlled abscess drainage the patient's condition improved. Because of the severe destruction of the spinal segment concerned and because of the epidural abscess formation a vertebrectomy of T10 and surgical debridement of the paravertebral soft tissue via thoracotomy became urgently necessary. The spine was stabilized by interposing a cage and an anterolateral monobar system. M. xenopi could be proven by PCR out of the intraoperative specimen. After operation and antituberculotic therapy there was a fast convalescence. Diagnostics, therapy, and clinical outcome are discussed.

Cavitary pulmonary disease

A pulmonary cavity is a gas-filled area of the lung in the center of a nodule or area of consolidation and may be clinically observed by use of plain chest radiography or computed tomography. Cavities are present in a wide variety of infectious and noninfectious processes. This review discusses the differential diagnosis of pathological processes associated with lung cavities, focusing on infections associated with lung cavities. The goal is to provide the clinician and clinical microbiologist with an overview of the diseases most commonly associated with lung cavities, with attention to the epidemiology and clinical characteristics of the host.

Mycobacterium xenopi multiplies within human macrophages and enhances HIV replication in vitro

Mycobacterium xenopi can cause opportunistic infections, particularly in persons infected with human immunodeficiency virus type 1 (HIV-1). The primary focus of this effort was to determine if M. xenopi isolates could survive and grow in human peripheral blood macrophage (MPhi), and if these isolates could promote the replication of HIV-1 in vitro. M. xenopi bacilli survived and replicated 10-fold within 48 h in human MPhi while avirulent Mycobacterium smegmatis, did not grow within the MPhi. M. xenopi bacilli when cultured with peripheral blood mononuclear cells enhanced HIV-1 replication 30- and 50-fold with the macrophage-tropic HIV-1(Ba-L) and 50- and 75-fold with T-cell-tropic strain HIV-1(LAI) by 6 days post-infection when compared to M. smegmatis. The enhanced HIV replication was associated with increased production of TNF-alpha. Partial inhibition of HIV-1 induction was observed using a neutralizing anti-TNF-alpha monoclonal antibody, pentoxifylline, and matrix metalloproteinase (MMP) inhibitor I. Similar mechanisms of pathogenesis among mycobacterial species may help elucidate better treatment approaches in HIV co-infected persons.