Introduction Pasteurella infections are an important cause of morbidity, particularly in elderly patients, and can present in a wide variety of clinical guises. Pasteurella spp. are small Gram-negative coccobacilli that are found as commensals of the upper respiratory tract in a variety of mammals, especially felines. A history of an animal bite, scratch or lick may only be elicited in a patient retrospectively once the organism has been isolated.

Results During this 5-year period 608 isolates of Pasteurella were identified from 539 patients. Clinical presentations included bacteraemias in 14 patients (see table 1). Of note, patient 5 presented with recurrent P. multocida bacteraemia on 2 occasions 3 years apart. This patient was frail and elderly, prone to skin tears, partial to her domestic cat and had a background of chronic renal impairment. One patient from this series of 14 was known to have died from sepsis within 48 hours of the blood culture. He had a history of leg cellulitis one month prior to presenting in septic shock and a background of chronic renal impairment and severe ischaemic heart disease.

SPECTRUM OF DISEASE CAUSED BY PASTEURELLA SPP

IN A DIAGNOSTIC LABORATORY OVER 5 YEARS

Conclusion This review of data highlights the diverse and often serious clinical presentations associated with Pasteurella infection. Laboratory identification is often key to eliciting an antecedent history of animal contact.

Methods The clinical spectrum of Pasteurella infections was evaluated from retrospective analysis of over 5 years of laboratory data from Sullivan Nicolaides Pathology, a large community-based private diagnostic pathology laboratory in Queensland, from January 2009-May 2014. Clinical details were obtained from both scrutiny of pathology request forms and from communication with referring clinicians. Laboratory identification of isolates was confirmed using the commercial system VITEK-2 (Biomérieux). Mannitol fermentation was used to differentiate P. multocida from P. canis when VITEK identification showed poor discrimination between the species. Since early 2014 VITEK MS (MALDI-TOF, Biomérieux) has been validated in our laboratory for identification of P. multocida.

Bygott J1, Robson J1

1Sullivan Nicolaides Pathology, Brisbane, Australia

Table 1: Clinical features of Pasteurella bacteraemias

PATIENT AGE SEX ISOLATE CLINICAL FEATURES

ANIMAL EXPOSURE

1 93 F P. multocida Fevers; leg cellulitis Cat - multiple scratches

2 89 M P. multocida Confusion; leukocytosis Not known 3 87 M P. multocida Fevers; rigors; cellulitis; concomitant bilateral pneumonia Stray cat - scratch

4 78 M P. multocida Fevers; infected leg bite site Cat - bite 5a 83 F P. multocida Fevers; cellulitis Cat - scratch 5b 86 F P. multocida Fevers; respiratory symptoms Cat – no bite/scratch

recalled 6 44 M P. canis Spina bifida. Fevers; infected sacral pressure sore Dog - close daily

contact/shares bed 7 91 M P. multocida Septic shock, prior cellulitis, ?infected THR.

Died within 48 hours of blood culture Cat - scratch

8 87 F P. multocida Fevers; cellulitis Not known 9 87 M P. multocida Chronic leg ulcers; scratches. Fevers; cellulitis Cat - scratch 10 74 M P. multocida Preceding skin tear from trauma. Fevers; cellulitis Dog – frequent licks 11 67 M P. multocida Acute Myeloid Leukaemia. Non-neutropenic sepsis.

Respiratory symptoms Not known

12 68 M P. multocida Myeloma. Dog bite 5 days prior; no cellulitis Dog bite 13 86 F P. multocida Diabetes. Fevers; leg cellulitis No animal exposure; in

residential care 14 80 F P. multocida Chronic leg ulcer. Fevers; cellulitis Dog (puppy) – licks only

70% of patients with Pasteurella isolated from any site were aged > 50 years (average age 58 years). 63% of patients identified with Pasteurella infection were female. The aged population was over-represented for all clinical presentations apart from outpatient skin and soft tissue infections (see Figure 1). The majority of isolates (72.5%) were identified as P. multocida, which is commensal flora of the oral cavity of both felines and canines. P. canis, which is found exclusively in canines, accounted for 20.4% of cases. A minority of cases was attributed to P. pneumotropica, found in rodents and canines. 5.2% of cases were unspeciated, due to lack of availability of mannitol slopes or VITEK MS in the laboratory at the time.

The patient was a 53 year old male with congenital renal disease who had been on CAPD (Continuous Ambulatory Peritoneal Dialysis) for 1 year and awoke with fever and a cloudy dialysate. Pasteurella multocida was subsequently isolated from the dialysate. Retrospectively he had noted leakage from tubing the previous day and conceded that his cat had been sprawled over the bag. This patient has subsequently undergone successful renal transplantation. CAPD-associated Pasteurella peritonitis has previously been described, albeit rarely.1 Box 1: Case of patient with Pasteurella CAPD-associated peritonitis

Figure 1: Numbers of Pasteurella isolates according to site and age group

Haematogenously acquired joint infections were found in 4 patients, all with prosthetic knee joint replacements. Skin and soft tissue infections accounted for the majority of clinical presentations and were found in 445 patients; associated with a 15% hospitalization rate. In one patient P. multocida was isolated from fluid from an infected mastectomy site.

Pasteurella spp were isolated from respiratory tract specimens in 71 patients, with a 17% hospitalization rate. The majority of respiratory specimens were sputum samples, however 3 isolates were from bronchial washes and one from an ear swab. The patient with the ear discharge subsequently, 4 months later, had Pasteurella isolated from a sputum sample in the setting of COPD. Additionally there was a single CAPD infection identified (see Box 1) and single isolates respectively from both urine (female patient with pyuria and a history of recurrent E. coli urinary tract infections) and vaginal swab (post-menopausal patient with a watery discharge).

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OUTPATIENT   SKIN  SWAB

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BODY  FLUID

UROGENITAL

Reference: 1. Cooke F et al. A case of Pasteurella multocida peritoneal dialysis associated peritonitis and review of the literature. Int J Infect Dis 2004; 8: 171