Changing spectrum of pathogens isolated from abscesses at a rural hospital

Author(s):
Hugo Bonatti; Sridhar Gona; Aaron George

Background:

The spectrum of pathogens identified from abscesses is expanding due to changing demographics, development of antibiotic resistance and improved microbiology technology allowing for better identification of unusual microorganisms.

Hypothesis:

Whereas MRSA is now the most common organism causing abcsesses, many other pathogens must be considered.

Methods:

The microbiology database of a rural hospital was queried for isolated pathogens from 2018 to 2022. Of the 15451 investigated positive specimens, 2392 cultures (1985 patients) were from drained abscesses.

Results:

51.4% of patients were male and median age was 47.9 years (range 1 day to 100.1 years). Abscess location included head/neck (8%), upper (16%), lower extremity (22%), trunk (25%), groin&perineal/perianal region (19%), others (10%). 77% of specimens grew one and 22% multiple organisms. In 748 cases (31%) in addition to pathogens normal flora was reported out, in 4% no aerobic, in 26% no anaerobic growth was observed. Microscopy showed WBC (83%), Gram+ cocci (63%), Gram+ rods (13%), Gram negative rods (18%); no organisms (33%). Staphylococci were isolated from 2392 isolates (59%) with Staphylococcus aureus accounting for 1352 (800 ie 59% Methicillin resistant). 498 specimens grew streptococci (pyogenes 86, agalactiae 165, group anginosus 120, various groups 67). E.coli (n=142), Proteus spp (65), Klebsiella spp (56) and Pseudomonas aeruginosa (53) were the most common Gram negative rods. Bacteroides and Prevotella spp accounted for 285 isolates. In 64 cases Candida spp were cultured. Rare/unusual pathogens such as Finegoldia magna (90), Peptostreptococcus spp (76), Peptoniphilus asaccharolyticus (42), Anaerococcus prevotii (39)  and others grew in 383 specimens (16%). Table 1 lists pathogens recovered in <1% of specimens.

Conclusions:

Although MRSA has emerged as most common pathogen (33%) in this study, recognition of rare pathogens is equally important as their exact significance and pathogenicity as well as resistance patterns in human infections are commonly poorly investigated. More research in this field such multicenter reports is needed.