Acute bacterial arthritis caused by group C streptococci

Impending rupture of mycotic aortic aneurysm infected with Streptococcus equi subspecies zooepidemicus

Streptococcus equi subspecies zooepidemicus is a beta-haemolytic, group C streptococcal bacterium. Although it is an opportunistic pathogen commonly found in horses, transmission to human can lead to severe infections. Here, we present a patient with S. equi subspecies zooepidemicus bacteraemia and consequent development of mycotic aneurysms.

Infections Caused by Group C and G Streptococcus (Streptococcus dysgalactiae subsp. equisimilis and Others): Epidemiological and Clinical Aspects

Streptococci carrying serogroup C and G antigens, and in particular, Streptococcus dysgalactiae subsp. equisimilis (SDSE), are emerging human pathogens that are increasingly isolated from patients with a myriad of infections that range from mundane to life-threatening. SDSE is microbiologically similar to Streptococcus pyogenes. These streptococci frequently cause infections of the throat and skin and soft tissues. Moreover, they may invade the bloodstream and disseminate widely to many deep tissue sites, including the endocardium. Life-threatening invasive infections due to SDSE, including the streptococcal toxic shock syndrome, occur most frequently in patients with severe underlying medical diseases. Treatment with penicillin is adequate under most circumstances, but treatment failure occurs. SDSE may also be resistant to other antibiotic classes including tetracyclines, macrolides, and clindamycin. Most human infections caused by groups C and G streptococci are transmitted from person to person, but infections due to Streptococcus equi subsp. zooepidemicus (and, rarely, to S. equi subsp. equi) are zoonoses. Transmission of these latter species occurs by animal contact or by contamination of food products and has been associated with the development of poststreptococcal glomerulonephritis. Members of the Streptococcus anginosus group, usually classified with the viridans group of streptococci, are associated with a variety of pyogenic infections.

Pathogenicity Factors in Group C and G Streptococci

Initially recognized zoonoses, streptococci belonging to Lancefield group C (GCS) and G (GGS) were subsequently recognised as human pathogens causing a diverse range of symptoms, from asymptomatic carriage to life threatening diseases. Their taxonomy has changed during the last decade. Asymptomatic carriage is <4% amongst the human population and invasive infections are often in association with chronic diseases such as diabetes, cardiovascular diseases or chronic skin infections. Other clinical manifestations include acute pharyngitis, pneumonia, endocarditis, bacteraemia and toxic-shock syndrome. Post streptococcal sequalae such as rheumatic fever and acute glomerulonephritis have also been described but mainly in developed countries and amongst specific populations. Putative virulence determinants for these organisms include adhesins, toxins, and other factors that are essential for dissemination in human tissues and for interference with the host immune responses. High nucleotide similarities among virulence genes and their association with mobile genetic elements supports the hypothesis of extensive horizontal gene transfer events between the various pyogenic streptococcal species belonging to Lancefield groups A, C and G. A better understanding of the mechanisms of pathogenesis should be apparent by whole-genome sequencing, and this would result in more effective clinical strategies for the pyogenic group in general.

Polyarthritis in Goat-Kids Caused by Streptococcus Equi Subspecies Zooepidemicus

Infectious arthritides in goats is mainly caused by mycoplasmas and Caprine Arthritis- Encephalitis virus (CAEV). Streptococcus equi subspecies zooepidemicus (S. zooepidemicus) is a member of Lancefield group C beta-hemolytic streptococcus that commonly colonizes the mucous membranes of healthy equids which is also capable to induce different pathological conditions in many animal species. In this paper we described a case of polyarthritis in four Alpine goat-kids caused by S. zooepidemicus. Goat-kids originated from a farm where sheep, llamas, shepherd dogs, cows and horses were kept with goats. During the external examination of carcasses, crusts and discrete hyperemia were seen on the earlobes beneath the ear tag, as well as swollen joints. Necropsy findings included severe fibrinous polyarthritis in all four examined kids. Shoulder, knee and hip joints were affected. From all affected joints S. zooepidemicus was isolated. Neither Mycoplasma spp. nor CAEV genome were detected from the affected joints. Most likely the goatkids were infected with S. zooepidemicus through the lesions on earlobes which were made after the tagging. As a possible source of bacteria, we recognized the horses and dogs. Due to the lack of any signs of illness in other animal species on the farm, as well as negative pathomorphological findings in other organs, we assumed that the isolated strain is highly adapted to goat-kids. Our report is the first described case of polyarthritis in goat-kids caused by S. zooepidemicus.

Human bacterial arthritis caused by Streptococcus zooepidemicus: report of a case

Septic arthritis caused by Streptococcus zooepidemicus is a rare event in humans. Of the four cases reported in the literature, only two patients had direct animal contact, and the portal of entry remained unclear in all cases. We report herein the case of a patient who suffered a purulent arthritis of the left shoulder caused by S. zooepidemicus, successfully treated in our department. A diagnostic FDG-PET-CT scan ruled out other foci of infection, but detected a hyperkeratotic plantar chronic soft tissue lesion of the left foot, acquired in a paragliding accident 10 years earlier. The fact that the patient habitually took care of his horses barefoot in boots, identifies the cutaneous portal of entry as most likely. To our knowledge this is the first report of a septic arthritis caused by S. zooepidemicus where a cutaneous entry route is described.

Streptococcal septic arthritis in adults. A study of 55 cases with a literature review

OBJECTIVES

To evaluate the rate of occurrence and characteristics of streptococcal septic arthritis.

METHODS

Retrospective single-center study of patients with bacteriologically documented septic arthritis admitted to a rheumatology department over a 20-year period.

RESULTS

Of 303 cases of septic arthritis, 55 (18%) were due to streptococci and 166 (55%) to Staphylococcus aureus (55%). As compared to patients with S. aureus arthritis, patients with streptococcal arthritis was more likely to be in female (56% vs. 36%, P < 0.006) and older than 60 years of age (71% vs. 58%), less likely to have comorbidities (36% vs. 56%), rheumatoid arthritis (5% vs. 19%, P < 0.01), or diabetes (2% vs. 15%, P < 0.01), and more likely to have cancer (13% vs. 7%). Involved joints and proportions of patients with arthritis in multiple joints were similar in two groups. Mortality was lower in the group with streptococcal infection (3.6% vs. 7.8%). The streptococci were distributed as follows: group A (n = 7), group B (n = 12), group C (n = 4), group D (n = 7), group F (n = 1), group G (n = 2), nongroupable (n = 14), nontypable (n = 1), and Streptococcus pneumoniae (n = 7). Groups A and B and nongroupable strains mainly affected women; group A selectively involved younger patients and group B very elderly patients. Comorbidity, most notably cancer, was common in patients with S. pneumoniae or group D streptococci. The portal of entry was often a skin lesion for groups A and B and a medical procedure for group D. Multiple joint involvement was common with groups A and B and prosthetic joint infection with groups B and C. Group A and S. pneumoniae were associated with severe systemic symptoms and extra articular foci of infection, whereas a smoldering course was more common with groups D and G and with nongroupable strains. Residual joint abnormalities were noted in half the patients, with no differences across groups.

CONCLUSIONS

The features of streptococcal septic arthritis vary according to the group of the causative organism and differ from those of S. aureus arthritis.

Group B streptococcus (Streptococcus agalactiae) pyogenic arthritis in nonpregnant adults

We analyzed the cases of pyogenic arthritis from group B streptococcus (GBS), or, in nonpregnant adults diagnosed in the Hospital Universitari de Bellvitge, a 1,000-bed tertiary care teaching hospital in Barcelona, Spain, during a 10-year period, and we reviewed the available literature to summarize the experience with this infectious entity. From the database of our institution, which does not attend pediatric, obstetric, or burn patients, we collected all microbiologically proven cases of infectious arthritis seen from January 1992 to December 2001. We excluded patients with infection limited to spine; patients with prosthetic joint infection; patients undergoing articular surgery during the year before diagnosis; and those with tuberculous, brucellar, or fungal arthritis. Of a total of 112 patients identified, GBS was the causative organism in 11 (10%) cases. We reviewed the literature using a MEDLINE search (1972-2001), and found 64 additional cases. Of the 75 patients, 34 (45%) were men and 41 (55%) women, with ages ranging from 20 to 87 years (mean age, 57.9 +/- 14.9 yr); 37 patients (49%) were over 60 years. Sixty-eight percent (51/75) of the patients presented with monoarthritis, while in 32% (24/75) more than 1 joint was involved. The most common location was the knee (36%), followed by the shoulder (25%). In 66% (43/65) of cases, bacteremia was documented. In 64% (47/74) of patients, a systemic predisposing factor for infection was noted; the most common conditions were diabetes mellitus, malignancies, and chronic liver diseases. In 31% (23/75) of patients, a concomitant infectious process due to the same microorganism was found, mainly vertebral osteomyelitis and urinary tract infection. Penicillin was the main antibiotic used after bacterial identification; surgical drainage was performed in 36% (27/75) of cases. The overall mortality rate was 9% (7/75). GBS is now a significant causative agent of pyogenic arthritis in nonpregnant adults. In this population, joint infection by GBS is a disease that mainly affects aged patients with underlying medical illnesses; polyarticular involvement, bacteremia, and the presence of a concomitant infectious process are frequent conditions. The case-fatality rate is substantial.