Sexually acquired Salmonella Typhi urinary tract infection

Introduction

While Salmonella Typhi bacteriuria can occur through microbial dissemination during an episode of typhoid fever, it is a rare finding. ¹ Those cases reported follow ingestion of the pathogen, with subsequent positive stool and blood cultures, and are often in the context of urinary tract abnormalities or nephrolithiasis.^2,3 There are no previous case reports in the literature of isolated urinary S. Typhi thought to have been acquired through sexual contact.

Case report

A 22-year-old man who has sex with men (MSM) presented for HIV testing with seroconversion symptoms and was found to be HIV-positive. CD4 cell count at diagnosis was 475 cells/mm³ (35%) and serum viral load was 546,263 copies/ml.

At review the patient complained of non-specific urinary symptoms. Urinalysis was positive for blood, protein and leucocytes. He was commenced on empirical trimethoprim 200 mg twice daily for two weeks as per local guidelines. S. Typhi was isolated from culture of a mid-stream urine sample. The patient had had a self-limiting afebrile diarrhoeal illness two weeks prior to onset of urinary symptoms, but had fully recovered within 48 hours. Stool and blood cultures were repeatedly negative. All blood tests including C-reactive protein were normal. The S. Typhi isolate was ciprofloxacin-sensitive and he completed a one-week course of ciprofloxacin 500 mg twice daily oral treatment with subsequent negative urine cultures.

The patient had no significant past medical history. He had not travelled abroad for three years nor had contact with anyone with a diarrhoeal illness. He works in the hospitality industry. He reported unprotected insertive and receptive anal intercourse one month prior to HIV diagnosis, with a contact who has declined HIV testing. Since HIV diagnosis he had had several partners with whom he reported protected insertive and receptive anal intercourse.

Screening of all household contacts by the local public health team did not identify any other cases. No other recent local S. Typhi infections had been reported by microbiology laboratories. Partner notification of sexual contacts was carried out by our health adviser team, but thus far the traceable contacts have declined stool testing.

Discussion

The most common manifestation of S. Typhi infection is typhoid fever, also know as enteric fever, a life-threatening condition affecting about 21.5 million people annually, and causing 200,000 deaths. ⁴ The majority of cases occur in low-income countries, with small numbers among travellers returning from endemic areas. ⁵ Outbreaks occur when an infected person contaminates food or water sources with faecal matter, often through poor hand hygiene.

The incubation period is typically between five and 21 days. Typhoid fever is characterised by fever, headache, gastrointestinal symptoms, splenomegaly and leucopaenia. The bacteria enter the lymphatics via intestinal Peyer’s patches and from there haematogenous dissemination can lead to multi-organ involvement. Death ensues in up to 32% of cases of severe typhoid fever if not treated with appropriate antibiotics. Less than 5% of patients progress to a chronic carrier state, with biliary and gall-bladder colonisation and asymptomatic intermittent faecal shedding.

The commonest cause of invasive non-typhi salmonellosis (NTS) worldwide is advanced HIV disease, and recurrent bacteraemia is a striking finding in these cases. ⁶ HIV disease does not however seem to be associated with an increased susceptibility to, or a worse outcome from, typhoid fever^7,8 but may be associated with more atypical presentations of S. Typhi infection.^9,10

Multi-drug-resistant (MDR) strains of S. Typhi have emerged worldwide since the 1970s. Subsequent reduced susceptibility to fluoroquinolones was rapidly seen, but to date comprehensive resistance remains rare ¹¹ despite increasing concern. ¹² Third-generation cephalosporins have been used in some areas ¹³ with observed low-level and stable resistance to these agents. ¹⁴ In the UK, 30% of imported infections are MDR and 57% have decreased susceptibility to ciprofloxacin. ¹⁵ Optimal management depends on an understanding of geographical resistance patterns and on rapid susceptibility testing of the Salmonella isolate.

While there have been previous reports of typhoid glomerulonephritis complicating typhoid fever^16,17 and recent reports of urinalysis abnormalities in the absence of renal impairment, ¹⁸ S. Typhi infection of the genitourinary system remains rare, even in endemic areas. ¹ Cases reported have invariably been on the background of urinary tract abnormalities and have been accompanied by positive blood and/or stool cultures for S. Typhi^2,3,6 This patient’s renal function remained normal. No urinary tract imaging has been undertaken given the lack of preceding symptoms and the prompt clearance of infection with antibiotics.

There are cases which propose sexual transmission of pathogens, mainly Escherichia coli (E. coli), leading to urinary tract infection in heterosexual couples ¹⁹ and MSM,^20,21 with some studies proving linkage of E. coli isolates between partners, ²² but to date no reports of sexually acquired S. Typhi urinary infection. Typhoid has been described among MSM where the route of acquisition was thought to be oro-anal contact with subsequent pathogen ingestion, ²³ but while all patients in this outbreak had positive blood or stool cultures (or both), none had confirmed urinary S. Typhi In this case the patient had repeatedly negative blood and stool cultures, reducing the likelihood that this was a disseminated infection leading to urinary tract infection, and raising the possibility that the route of infection was through insertive anal intercourse with direct urethral inoculation with S. Typhi. Unfortunately, partner notification has not identified an acute or chronically infected contact with S. Typhi to further add weight to this theory.