The Brief Case: Strictly Anaerobic and Staining Acid Fast

CASE A38-year-old male with a past medical history of poorly controlled diabetes mellitus type 2 and hidradenitis suppurativa, a chronic inflammatory condition affecting apocrine glands of the axilla and groin, presented with 1 week of posterior neck swelling and pain. He noted having chronic, stable draining lesions in the axilla and groin but developed a new area of swelling and tenderness in the left posterior neck over the week prior to presentation. On presentation he was afebrile with a heart rate of 130 beats per min (bpm). Other vital signs were within normal limits. His exam was notable for a left-sided occiput large indurated area with mild erythema and tenderness to palpation without active drainage. Laboratory studies were notable for white blood cells, 22.2 103/mm3 (reference range, 4.0 103 to 11.0 103/mm3), and hemoglobin, 10.8 g/dL (reference range, 14.0 to 17.0 g/dL). Computed tomography of the soft tissues of the neck with contrast demonstrated a rim-enhancing hypodense collection in the subcutaneous tissues of the posterior neck measuring 3.1 by 6.1 by 3 cm with surrounding fat infiltration and phlegmonous change (Fig. 1). He was taken to the operating room by the Otolaryngology Department for incision and drainage. In the operating room he was found to have a left occipital abscess with copious purulence expressed with multiple pockets of pus and murky fluid. He was initially given one dose of vancomycin and piperacillin-tazobactam, which were stopped, and ampicillin-sulbactam was started postoperatively. Purulent fluid and a tissue specimen were collected during the incision and drainage procedure for the posterior neck abscess and were submitted for routine bacterial aerobic and anaerobic, fungal, and acid-fast bacillus (AFB) cultures. The direct Gram stain of the fluid showed Gram-variable rods with poor retention of crystal violet (Fig. 2A), but no organisms were observed on the Gram stain from tissue. Auramine-rhodamine (AR) stain of the fluid was read as positive (41,.30 organisms seen per 400 field) for acid-fast bacilli (AFB), and the tissue was also AR positive but with considerably fewer organisms (11, 2 to 20 organisms seen in a total of 50 400 fields). The aerobic (sheep’s blood, chocolate, and MacConkey agar, 3 days of incubation) and anaerobic (CDC anaerobic agar, 5 days of incubation in anaerobic environment) cultures showed no growth. Similarly, fungal cultures of the neck fluid aspirate showed no growth after 28 days, and AFB cultures on 7H11 and LJ-Gruff agar media and BD MGIT broth medium had no growth after 12 weeks (extended culture time because of positive smear). To confirm the AR result when the organism did not grow in culture, both Kinyoun (weakly positive) and modified Kinyoun (strongly positive) (Fig. 2B) stains were performed on the fluid aspirate. Because no organism grew in culture, the fluid specimen was sent to a reference lab (University of Washington) to be tested for tuberculous and nontuberculous mycobacteria by rpoB and hsp65 PCR and sequencing. Mycobacterium-specific targets were negative, but Lawsonella clevelandensis was identified via 16S rRNA primer sets included with the nontuberculousmycobacterium evaluation and subsequent 16S amplicon sequencing. He was treated with 7 days of intravenous ampicillin-sulbactam, 3 g every 6 h, while admitted as an inpatient. He was discharged with an additional 10 days of oral amoxicillin-clavulanate, 875 to 125 mg every 12 h. At outpatient follow-up his posterior Editor Carey-Ann D. Burnham, Pattern Bioscience Copyright © 2023 American Society for Microbiology. All Rights Reserved. Address correspondence to Elizabeth Gancher, elizabeth.gancher@jefferson.edu. The authors declare no conflict of interest. Published 23 May 2023