Aura 2016: first Australian report on antimicrobial use and resistance in human health

4.2 Acinetobacter baumannii

Health impact

Acinetobacter baumannii is an environmental organism that causes infections in patients with compromised physical barriers and immunity. The most common infections caused by this species are ventilator-associated pneumonia, and traumatic and burn wound infections. The species can cause sustained outbreaks in certain clinical settings, such as intensive care and burns units.

Treatment

Because of its pattern of intrinsic resistances, the preferred agents to treat serious A. baumannii infections are carbapenems.

Types and impact of resistance

A. baumannii and related species have a high propensity for developing resistance to multiple antimicrobial agents, including broad-spectrum agents such as carbapenems. Sometimes, they are only susceptible to potentially toxic antimicrobials, such as colistin.

A. baumannii and related species have a high propensity for developing resistance to multiple antimicrobial agents.

Key findings (Queensland)

Rates of resistance to key antimicrobial agents were low in Queensland in 2014 (Figure 4.1). Resistance rates were higher in hospitals than in the community (Figure 4.2), which might be attributable to more resistant strains being established in some hospital units.

Figure 4.1 Acinetobacter baumannii resistance to individual agents, 2014

Sources: OrgTRx (Queensland); Sullivan Nicolaides Pathology (Queensland and northern New South Wales)

Figure 4.2 Acinetobacter baumannii resistance, by clinical setting, 2014

na = not available (either not tested or tested against an inadequate number of isolates)

Sources: OrgTRx (public hospitals and health services); Sullivan Nicolaides Pathology (private hospitals and community)

Data table: Figure 4.2

Agent	Public hospitals and health services (n = 573), % resistant	Private hospitals (n = 54), % resistant	Community (n = 165), % resistant
Gentamicin	2.8	1.9	1.2
Ciprofloxacin	4.2	2.4	na
Meropenem	3.5	4.4	na

4.3 Enterobacteriaceae

Health impact

The Enterobacteriaceae is a large family of related bacteria. Many of its members are associated with infections in humans. Of these, Escherichia coli and Klebsiella pneumoniae are the most common and important species, and cause community- and hospital-associated infections. Enterobacter cloacae complex is a common pathogen in hospital care. The Enterobacteriaceae family also includes Salmonella and Shigella species; these are reported on separately in Sections 4.9 and 4.10.

E. coli, K. pneumoniae and Enterobacter cloacae are associated with a range of infections, including urinary tract infections, biliary infections, other intra-abdominal infections (including those following surgery, and often mixed with other pathogens) and septicaemia. Less frequently, these species are a cause of bacteraemia from intravascular lines and meningitis. E. coli is the most common cause of urinary tract infection and septicaemia.

Table 4.3 shows AGAR data for the most common clinical syndromes associated with Enterobacteriaceae. Urinary tract infections with these organisms are more common in females, while other clinical manifestations are more common in males.

Table 4.3 Principal clinical manifestations of infections with Enterobacteriaceae (all species, blood culture isolates), 2014

Clinical manifestation	Male	Female	Total	Males per 100 females
Urinary tract infection	834	1141	1975	73
Biliary tract infection (including cholangitis)	441	294	735	150
No focus (e.g. febrile neutropenia)	343	257	600	133
Intra-abdominal infection other than biliary tract	315	195	510	162
Other clinical syndrome	188	134	322	140
Device-related infection without metastatic focus	132	108	240	122
Skin and skin structure infection	90	45	135	200
Osteomyelitis/septic arthritis	24	15	39	160
Device-related infection with metastatic focus	9	5	14	180
Total	2376	2194	4570	108

Source: Australian Group on Antimicrobial Resistance (national)