Streptococcus mutans: a rare cause of retroperitoneal abscess.

Retroperitoneal abscesses are uncommonly encountered clinical entities and they represent serious surgical infections associated with significant mortality rates because of their insidious clinical manifestations and diagnostic difficulty. The source of retroperitoneal infections is usually an organ contained within or abutting the retroperitoneum, usually the kidney and the microorganisms most commonly isolated are gram-negative bacilli. Gram-positive cocci, mainly staphylococcal species and rarely streptococcal species, are a less common cause of retroperitoneal abscess and are usually isolated in cases of hematogenous spread. Treatment of retroperitoneal abscesses includes identification and treatment of underlying conditions, intravenous antibiotics and adequate surgical drainage of all well-defined collections. We present a rare case of retroperitoneal abscess caused by monomicrobial Streprococcus mutans infection and discuss the possible pathogenesis, clinical presentation, diagnosis and treatment.

Emergence of Proteus mirabilis carrying the bla metallo-beta-lactamase gene.

Seven genetically related Proteus mirabilis clinical isolates from a hospital in Thessaloniki, Greece, exhibited decreased susceptibility to imipenem and carried a bla(VIM-1) metallo-beta-lactamase gene. PCR mapping revealed that bla(VIM-1) was part of a class 1 integron that was probably located in the chromosome and also included the aacA7, dhfr and aadA genes. This is the first description of the bla(VIM-1) metallo-beta-lactamase gene in P. mirabilis.

Effects of interleukin-13 on antifungal activity of human monocytes against Candida albicans.

We investigated the effects of human interleukin-13 (IL-13) on human monocytes' (MNC) activities against Candida albicans, an important human pathogen. Increased phagocytosis of blastoconidia was observed after incubation with 50 U ml(-1) of IL-13 for 4 h or 48 h in the presence or absence of serum. The latter effect was inhibited by anti-IL-13 monoclonal antibody or mannose. Incubation of MNC with 50 U ml(-1) of IL-13 for 2 h significantly enhanced superoxide anion production in response to phorbol myristate acetate. IL-13 did not, however, alter the damage caused by MNC to hyphae, whereas it suppressed killing of blastoconidia. IL-13 has variable effects on MNC activities and may play an important immunoregulatory role against C. albicans.

Interleukin 10 suppresses phagocytic and antihyphal activities of human neutrophils.

We investigated the effects of human interleukin 10 (IL-10) on the antibacterial and antifungal activities of human neutrophils (PMNs) against Staphylococcus aureus and Candida albicans. Incubation of PMNs from healthy volunteers with 20-100 ng/ml of IL-10 at 37 degrees C for 1 h suppressed phagocytosis of serum-opsonized S. aureus (P=0.02) and blastoconidia of C. albicans (P<0.01). In contrast, 2-100 ng/ml of IL-10 had no effect on superoxide anion production upon stimulation with phorbol myristate acetate, N-formylmethionyl leucyl phenylalanine, C. albicans blastoconidia or pseudohyphae; neither did it significantly affect conidiocidal or bactericidal activities of PMNs. However, 20-100 ng/ml of IL-10 significantly decreased PMN-induced damage of C. albicans pseudohyphae (P=0.008). The suppression of phagocytic activity of PMNs against S. aureus and blastoconidia of C. albicans as well as the impairment of PMN-induced hyphal damage may have important implications for understanding the immunosuppressive profile of IL-10 in clinical usage.

Pathogenesis I: interactions of host cells and fungi.

The interactions of host cells and fungi during infection represent a complex interplay. Although T helper 1 (Th1)-mediated immunity is primarily responsible for acquired resistance to Paracoccidioides brasiliensis, studies have demonstrated that polymorphonuclear neutrophils play a critical role in providing an early resistance to this organism. One study has shown that the invasiveness of Candida albicans requires adherence, particularly to endothelial cells, which in turn are stimulated to express various cell-markers and pro-inflammatory cytokines as part of a proactive resistance to invasion. Somewhat in contrast to infection with C. albicans, it has been shown that the capsular glucuronoxylomannan of Cryptococcus neoformans causes the shedding of host-cell adherence molecules (L-selectins) needed for the migration of host-inflammatory cells to sites of infection and likely explains, in part, the reduced host inflammatory response to this organism. Resistance to aspergillosis is often associated with the immune status of the host. In one set of studies, it has been demonstrated that lymphocytes have little direct effect on the organism, but that antigen-presenting dendritic cells stimulate the production of Th1 cytokines, suggesting a positive role for the dendritic cell in host-response. Similarly, another study has shown that among the regulatory cytokine networks that Th2-associated cytokines (e.g., interleukin-10) likely play a detrimental role in the resistance of the host to Aspergillus fumigatus.

Disseminated infection due to Chrysosporium zonatum in a patient with chronic granulomatous disease and review of non-Aspergillus fungal infections in patients with this disease.

We report the first case of Chrysosporium zonatum infection in a 15-year-old male with chronic granulomatous disease who developed a lobar pneumonia and tibia osteomyelitis while on prophylaxis with gamma interferon. The fungus was isolated from sputum and affected bone, and hyphae were observed in the bone by histopathology. Therapy with amphotericin B eradicated the osteomyelitis and pneumonia, but pneumonia recurred in association with pericarditis and pleuritis during therapy with itraconazole. These manifestations subsided, and no recurrences occurred with liposomal amphotericin B therapy. Infections caused by Chrysosporium species are very rare, and C. zonatum has not previously been reported to cause mycosis in humans. This species, the anamorph of the heterothallic ascomycete Uncinocarpus orissi (family Onygenaceae), is distinguished by its thermotolerance, by colonies which darken from yellowish white to buff, and by club-shaped terminal aleurioconidia borne at the ends of short, typically curved stalks. The case isolate produced fertile ascomata in mating tests with representative isolates. The median (range) MICs for our isolate as well as those for two other human isolates and a nonhuman isolate determined by the National Committee for Clinical Laboratory Standards method adapted for moulds were 128 microg/ml (>128 microg/ml) for flucytosine, and 48 microg/ml (32 to >128 microg/ml) for fluconazole.